1
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He JY, Zhu C, Duan WX, Kong LX, Wang NN, Wang YZ, Fan ZY, Qiao XY, Xu H. Bifunctional Chiral Electrocatalysts Enable Enantioselective α-Alkylation of Aldehydes. Angew Chem Int Ed Engl 2024:e202401355. [PMID: 38967087 DOI: 10.1002/anie.202401355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 06/25/2024] [Accepted: 07/04/2024] [Indexed: 07/06/2024]
Abstract
Herein, we describe an innovative approach to the asymmetric electrochemical α-alkylation of aldehydes facilitated by a newly designed bifunctional chiral electrocatalyst. The highly efficient bifunctional chiral electrocatalyst combines a chiral aminocatalyst with a redox mediator. It plays a dual role as a redox mediator for electrooxidation, while simultaneously providing remarkable asymmetric induction for the stereoselective α-alkylation of aldehydes. Additionally, this novel catalyst exhibits enhanced catalytic activity and excellent stereoselective control comparable to conventional catalytic systems. As a result, this strategy provides a new avenue for versatile asymmetric electrochemistry. The electrooxidation of diverse phenols enables the C-H/C-H oxidative α-alkylation of aldehydes in a highly chemo- and stereoselective fashion. Detailed mechanistic studies by control experiments and cyclic voltammetry analysis demonstrate possible reaction pathways and the origin of enantio-induction.
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Affiliation(s)
- Jin-Yu He
- Engineering Research Center of Photoenergy Utilization for Pollution Control and Carbon Reduction, State Key Laboratory of Green Pesticide, College of Chemistry, Central China Normal University, Wuhan, 430079, China
| | - Cuiju Zhu
- Engineering Research Center of Photoenergy Utilization for Pollution Control and Carbon Reduction, State Key Laboratory of Green Pesticide, College of Chemistry, Central China Normal University, Wuhan, 430079, China
| | - Wen-Xi Duan
- Engineering Research Center of Photoenergy Utilization for Pollution Control and Carbon Reduction, State Key Laboratory of Green Pesticide, College of Chemistry, Central China Normal University, Wuhan, 430079, China
| | - Ling-Xuan Kong
- Engineering Research Center of Photoenergy Utilization for Pollution Control and Carbon Reduction, State Key Laboratory of Green Pesticide, College of Chemistry, Central China Normal University, Wuhan, 430079, China
| | - Na-Na Wang
- Engineering Research Center of Photoenergy Utilization for Pollution Control and Carbon Reduction, State Key Laboratory of Green Pesticide, College of Chemistry, Central China Normal University, Wuhan, 430079, China
| | - Yan-Zhao Wang
- Engineering Research Center of Photoenergy Utilization for Pollution Control and Carbon Reduction, State Key Laboratory of Green Pesticide, College of Chemistry, Central China Normal University, Wuhan, 430079, China
| | - Zhi-Yong Fan
- Engineering Research Center of Photoenergy Utilization for Pollution Control and Carbon Reduction, State Key Laboratory of Green Pesticide, College of Chemistry, Central China Normal University, Wuhan, 430079, China
| | - Xin-Ying Qiao
- Engineering Research Center of Photoenergy Utilization for Pollution Control and Carbon Reduction, State Key Laboratory of Green Pesticide, College of Chemistry, Central China Normal University, Wuhan, 430079, China
| | - Hao Xu
- Engineering Research Center of Photoenergy Utilization for Pollution Control and Carbon Reduction, State Key Laboratory of Green Pesticide, College of Chemistry, Central China Normal University, Wuhan, 430079, China
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2
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Hu L, Chakraborty S, Tumanov N, Wouters J, Robiette R, Berionni G. Regulating iminophosphorane PN bond reactivity through geometric constraints with cage-shaped triarylphosphines. Chem Commun (Camb) 2024; 60:7073-7076. [PMID: 38888188 DOI: 10.1039/d4cc01868k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2024]
Abstract
Structure-reactivity investigations and quantum-chemical parametrization of steric and electronic properties of geometrically constrained iminophosphoranes enabled the design of new frustrated Lewis pairs and revealed unusual properties at the phosphonium center embedded in the cage-shaped triptycene tricyclic scaffold.
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Affiliation(s)
- Lei Hu
- Université de Namur, Department of Chemistry, Namur Institute of Structured Matter (NISM), Rue de Bruxelles 61, Namur 5000, Belgium.
- Université Catholique de Louvain, Institute of Condensed Matter and Nanosciences, Place Louis Pasteur 1 box L4.01.02, Louvain-la-Neuve 1348, Belgium.
| | - Sayandip Chakraborty
- Université de Namur, Department of Chemistry, Namur Institute of Structured Matter (NISM), Rue de Bruxelles 61, Namur 5000, Belgium.
| | - Nikolay Tumanov
- Université de Namur, Department of Chemistry, Namur Institute of Structured Matter (NISM), Rue de Bruxelles 61, Namur 5000, Belgium.
| | - Johan Wouters
- Université de Namur, Department of Chemistry, Namur Institute of Structured Matter (NISM), Rue de Bruxelles 61, Namur 5000, Belgium.
| | - Raphaël Robiette
- Université Catholique de Louvain, Institute of Condensed Matter and Nanosciences, Place Louis Pasteur 1 box L4.01.02, Louvain-la-Neuve 1348, Belgium.
| | - Guillaume Berionni
- Université de Namur, Department of Chemistry, Namur Institute of Structured Matter (NISM), Rue de Bruxelles 61, Namur 5000, Belgium.
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3
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Bieniek J, Nater DF, Eberwein SL, Schollmeyer D, Klein M, Waldvogel SR. Efficient and Sustainable Electrosynthesis of N-Sulfonyl Iminophosphoranes by the Dehydrogenative P-N Coupling Reaction. JACS AU 2024; 4:2188-2196. [PMID: 38938819 PMCID: PMC11200248 DOI: 10.1021/jacsau.4c00156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 03/31/2024] [Accepted: 04/03/2024] [Indexed: 06/29/2024]
Abstract
Iminophosphoranes are commonly used reagents in organic synthesis and are, therefore, of great interest. An efficient and sustainable iodide-mediated electrochemical synthesis of N-sulfonyl iminophosphoranes from readily available phosphines and sulfonamides is reported. This method features low amounts of supporting electrolytes, inexpensive electrode materials, a simple galvanostatic setup, and high conversion rates. The broad applicability could be demonstrated by synthesizing 20 examples in yields up to 90%, having diverse functional groups including chiral moieties and biologically relevant species. Furthermore, electrolysis was performed on a 20 g scale and could be run in repetitive mode by recycling the electrolyte, which illustrates the suitability for large-scale production. A reaction mechanism involving electrochemical mediation by the iodide-based supporting electrolyte is proposed, completely agreeing with all of the results.
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Affiliation(s)
- Jessica
C. Bieniek
- Department
of Chemistry, Johannes Gutenberg University
Mainz, Duesbergweg 10–14, 55128 Mainz, Germany
| | - Darryl F. Nater
- Department
of Chemistry, Johannes Gutenberg University
Mainz, Duesbergweg 10–14, 55128 Mainz, Germany
- Max-Planck-Institute
for Chemical Energy Conversion, Stiftstraße 34–36, 45470 Mülheim an der Ruhr, Germany
| | - Sara L. Eberwein
- Department
of Chemistry, Johannes Gutenberg University
Mainz, Duesbergweg 10–14, 55128 Mainz, Germany
| | - Dieter Schollmeyer
- Department
of Chemistry, Johannes Gutenberg University
Mainz, Duesbergweg 10–14, 55128 Mainz, Germany
| | - Martin Klein
- Department
of Chemistry, Johannes Gutenberg University
Mainz, Duesbergweg 10–14, 55128 Mainz, Germany
| | - Siegfried R. Waldvogel
- Department
of Chemistry, Johannes Gutenberg University
Mainz, Duesbergweg 10–14, 55128 Mainz, Germany
- Institute
of Biological and Chemical Systems—Functional Molecular Systems
(IBCS-FMS), Hermann-von-Helmholtz-Platz
1, 76344 Eggenstein-Leopoldshafen, Germany
- Max-Planck-Institute
for Chemical Energy Conversion, Stiftstraße 34–36, 45470 Mülheim an der Ruhr, Germany
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4
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Rufino VC, Pliego JR. Bifunctional iminophosphorane organocatalyst with additional hydrogen bonding: Calculations predict enhanced catalytic performance in a michael addition reaction. J Mol Graph Model 2024; 129:108760. [PMID: 38513601 DOI: 10.1016/j.jmgm.2024.108760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 02/29/2024] [Accepted: 03/11/2024] [Indexed: 03/23/2024]
Abstract
A new iminophosphorane-thiourea superbase was rationally designed and investigated as an organocatalyst for the enantioselective Michael addition reaction of nitromethane to 4-phenylbut-3-en-2-one. Starting from an iminophosphorane-thiourea organocatalyst structure already known, we have used theoretical calculations to determine the structures of transition states involved in the carbon-carbon bond formation step and carried out structural modifications to accelerate the reaction rate and to increase the enantioselectivity. The effective structural modification was adding a rigid hydroxyl group able to make an additional hydrogen bond to the transition state, producing a substantial decrease of the ΔG‡ by 7 kcal mol-1. The enantiomeric excess is predicted to be above of 97% using the reliable M06-2X and ωB97M - V functionals. The determination of the complete reaction mechanism and free energy profile was followed by a detailed microkinetic analysis. The present study points out a new direction for structural modifications on this kind of organocatalyst.
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Affiliation(s)
- Virginia C Rufino
- Departamento de Ciências Naturais, Universidade Federal de São João del-Rei, 36301-160, São João del-Rei, MG, Brazil
| | - Josefredo R Pliego
- Departamento de Ciências Naturais, Universidade Federal de São João del-Rei, 36301-160, São João del-Rei, MG, Brazil.
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5
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Tampellini N, Mercado BQ, Miller SJ. Scaffold-Oriented Asymmetric Catalysis: Conformational Modulation of Transition State Multivalency during a Catalyst-Controlled Assembly of a Pharmaceutically Relevant Atropisomer. Chemistry 2024; 30:e202401109. [PMID: 38507249 PMCID: PMC11132932 DOI: 10.1002/chem.202401109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Accepted: 03/20/2024] [Indexed: 03/22/2024]
Abstract
A new class of superbasic, bifunctional peptidyl guanidine catalysts is presented, which enables the organocatalytic, atroposelective synthesis of axially chiral quinazolinediones. Computational modeling unveiled the conformational modulation of the catalyst by a novel phenyl urea N-cap, that preorganizes the structure into the active, folded state. A previously unanticipated noncovalent interaction involving a difluoroacetamide acting as a hybrid mono- or bidentate hydrogen bond donor emerged as a decisive control element inducing atroposelectivity. These discoveries spurred from a scaffold-oriented project inspired from a fascinating investigational BTK inhibitor featuring two stable chiral axes and relies on a mechanistic framework that was foreign to the extant lexicon of asymmetric catalysis.
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Affiliation(s)
- Nicolò Tampellini
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, CT 06511 (USA)
| | - Brandon Q. Mercado
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, CT 06511 (USA)
| | - Scott J. Miller
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, CT 06511 (USA)
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6
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Raczyńska ED, Gal JF, Maria PC. Strong Bases and beyond: The Prominent Contribution of Neutral Push-Pull Organic Molecules towards Superbases in the Gas Phase. Int J Mol Sci 2024; 25:5591. [PMID: 38891779 PMCID: PMC11172071 DOI: 10.3390/ijms25115591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 05/14/2024] [Accepted: 05/16/2024] [Indexed: 06/21/2024] Open
Abstract
In this review, the principles of gas-phase proton basicity measurements and theoretical calculations are recalled as a reminder of how the basicity PA/GB scale, based on Brønsted-Lowry theory, was constructed in the gas-phase (PA-proton affinity and/or GB-gas-phase basicity in the enthalpy and Gibbs energy scale, respectively). The origins of exceptionally strong gas-phase basicity of some organic nitrogen bases containing N-sp3 (amines), N-sp2 (imines, amidines, guanidines, polyguanides, phosphazenes), and N-sp (nitriles) are rationalized. In particular, the role of push-pull nitrogen bases in the development of the gas-phase basicity in the superbasicity region is emphasized. Some reasons for the difficulties in measurements for poly-functional nitrogen bases are highlighted. Various structural phenomena being in relation with gas-phase acid-base equilibria that should be considered in quantum-chemical calculations of PA/GB parameters are discussed. The preparation methods for strong organic push-pull bases containing a N-sp2 site of protonation are briefly reviewed. Finally, recent trends in research on neutral organic superbases, leaning toward catalytic and other remarkable applications, are underlined.
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Affiliation(s)
- Ewa Daniela Raczyńska
- Department of Chemistry, Warsaw University of Life Sciences (SGGW), ul. Nowoursynowska 159c, 02-776 Warsaw, Poland
| | - Jean-François Gal
- Institut de Chimie de Nice, UMR 7272, Université Côte d’Azur, Parc Valrose, 06108 Nice, France;
| | - Pierre-Charles Maria
- Institut de Chimie de Nice, UMR 7272, Université Côte d’Azur, Parc Valrose, 06108 Nice, France;
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7
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Mdluli V, Lehnherr D, Lam YH, Chaudhry MT, Newman JA, DaSilva JO, Regalado EL. Electrosynthesis of iminophosphoranes and applications in nickel catalysis. Chem Sci 2024; 15:5980-5992. [PMID: 38665537 PMCID: PMC11041257 DOI: 10.1039/d3sc05357a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2023] [Accepted: 03/06/2024] [Indexed: 04/28/2024] Open
Abstract
P(v) iminophosphorane compounds are accessed via electrochemical oxidation of commercially available P(iii) phosphines, including mono-, di- and tri-dentate phosphines, as well as chiral phosphines. The reaction uses inexpensive bis(trimethylsilyl)carbodiimide as an efficient and safe aminating reagent. DFT calculations, cyclic voltammetry, and NMR studies provide insight into the reaction mechanism. The proposed mechanism reveals a special case of sequential paired electrolysis. DFT calculations of the frontier orbitals of an iminophosphorane are compared with those of the analogous phosphines and phosphine oxides. X-ray crystallographic studies of the ligands as well as a Ni-coordination complex provide structural insight for these ligands. The utility of these iminophosphoranes as ligands is demonstrated in nickel-catalyzed cross-electrophile couplings including C(sp2)-C(sp3) and C(sp2)-C(sp2) couplings, an electrochemically driven C-N cross-coupling, and a photochemical arylative C(sp3)-H functionalization. In some cases, these new ligands provide improved performance over commonly used sp2-N-based ligands (e.g. 4,4'-di-tert-butyl-2,2'-bipyridine).
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Affiliation(s)
- Velabo Mdluli
- Process Research and Development, Merck & Co., Inc. Rahway New Jersey 07065 USA
| | - Dan Lehnherr
- Process Research and Development, Merck & Co., Inc. Rahway New Jersey 07065 USA
| | - Yu-Hong Lam
- Modeling and Informatics, Merck & Co., Inc. Rahway New Jersey 07065 USA
| | - Mohammad T Chaudhry
- Analytical Research and Development, Merck & Co., Inc. Rahway New Jersey 07065 USA
| | - Justin A Newman
- Analytical Research and Development, Merck & Co., Inc. Rahway New Jersey 07065 USA
| | - Jimmy O DaSilva
- Analytical Research and Development, Merck & Co., Inc. Rahway New Jersey 07065 USA
| | - Erik L Regalado
- Analytical Research and Development, Merck & Co., Inc. Rahway New Jersey 07065 USA
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8
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Formica M, Ferko B, Marsh T, Davidson TA, Yamazaki K, Dixon DJ. Second Generation Catalytic Enantioselective Nucleophilic Desymmetrization at Phosphorus (V): Improved Generality, Efficiency and Modularity. Angew Chem Int Ed Engl 2024; 63:e202400673. [PMID: 38381534 DOI: 10.1002/anie.202400673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 02/20/2024] [Accepted: 02/21/2024] [Indexed: 02/23/2024]
Abstract
A broadly improved second generation catalytic two-phase strategy for the enantioselective synthesis of stereogenic at phosphorus (V) compounds is described. This protocol, consisting of a bifunctional iminophosphorane (BIMP) catalyzed nucleophilic desymmetrization of prochiral, bench stable P(V) precursors and subsequent enantiospecific substitution allows for divergent access to a wide range of C-, N-, O- and S- substituted P(V) containing compounds from a handful of enantioenriched intermediates. A new ureidopeptide BIMP catalyst/thiaziolidinone leaving group combination allowed for a far wider substrate scope and increased reaction efficiency and practicality over previously established protocols. The resulting enantioenriched intermediates could then be transformed into an even greater range of distinct classes of P(V) compounds by displacement of the remaining leaving group as well as allowing for even further diversification downstream. Density functional theory (DFT) calculations were performed to pinpoint the origin of enantioselectivity for the BIMP-catalyzed desymmetrization, to rationalize how a superior catalyst/leaving group combination leads to increased generality in our second-generation catalytic system, as well as shed light onto observed stereochemical retention and inversion pathways when performing late-stage enantiospecific SN2@P reactions with Grignard reagents.
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Affiliation(s)
- Michele Formica
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, OX1 3TA, Oxford, UK
| | - Branislav Ferko
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, OX1 3TA, Oxford, UK
| | - Thomas Marsh
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, OX1 3TA, Oxford, UK
| | - Timothy A Davidson
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, OX1 3TA, Oxford, UK
| | - Ken Yamazaki
- Division of Applied Chemistry, Okayama University, Tsushimanaka, Okayama, 700-8530, Japan
| | - Darren J Dixon
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, OX1 3TA, Oxford, UK
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9
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Kitzinger KM, Giordano MT, de Jesús Cruz P, Johnson JS. Diastereoselective (3 + 3)-Annulations of Trisubstituted Michael Acceptors for Access to Polyfunctional Cyclohexanones. J Org Chem 2024; 89:5878-5882. [PMID: 38501591 PMCID: PMC11181156 DOI: 10.1021/acs.joc.4c00157] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/20/2024]
Abstract
Michael-aldol domino reactions are powerful tools for rapidly assembling carbocyclic scaffolds. We herein disclose a base-catalyzed Michael-aldol domino reaction of trisubstituted Michael acceptors with β-keto ester nucleophiles. The cyclohexanone products are obtained in excellent diastereoselectivity (up to >20:1 dr) and good yields (up to 84%). An attractive practical consideration is that pure products are isolated directly via filtration of the unpurified reaction mixtures. Further functionalization of the cyclohexanones is achieved without perturbation of stereocenters installed through the preceding annulation.
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Affiliation(s)
- Katelyn M Kitzinger
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Mitchell T Giordano
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Pedro de Jesús Cruz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Jeffrey S Johnson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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10
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Lee H, Nam H, Lee SY. Enantio- and Diastereoselective Variations on α-Iminonitriles: Harnessing Chiral Cyclopropenimine-Thiourea Organocatalysts. J Am Chem Soc 2024; 146:3065-3074. [PMID: 38281151 DOI: 10.1021/jacs.3c09911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2024]
Abstract
Chiral 1-pyrrolines containing a nitrile motif serve as crucial structural scaffolds in biologically active molecules and exhibit diversity as building blocks owing to their valuable functional groups; however, the asymmetric synthesis of such compounds remains largely unexplored. Herein, we present an enantio- and diastereoselective method for the synthesis of α-chiral nitrile-containing 1-pyrroline derivatives bearing vicinal stereocenters through the design and introduction of chiral cyclopropenimine-based bifunctional catalysts featuring a thiourea moiety. This synthesis entails a highly stereoselective conjugate addition of α-iminonitriles to a wide array of enones, followed by cyclocondensation, thereby affording a series of cyanopyrroline derivatives, some of which contain all-carbon quaternary centers. Moreover, we demonstrate the synthetic utility of this strategy by performing a gram-scale reaction with 1% catalyst loading, along with a variety of chemoselective transformations of the product, including the synthesis of a vildagliptin analogue. Finally, we showcase the selective synthesis of all four stereoisomers of the cyanopyrroline products through trans-to-cis isomerization, highlighting the versatility of our approach.
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Affiliation(s)
- Hooseung Lee
- Department of Chemistry, Yonsei University, Seoul 03722, Republic of Korea
| | - Hyeongwoo Nam
- Department of Chemistry, Yonsei University, Seoul 03722, Republic of Korea
| | - Sarah Yunmi Lee
- Department of Chemistry, Yonsei University, Seoul 03722, Republic of Korea
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11
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Popovici I, Lognon E, Casaretto N, Monari A, Auffrant A. Electronic Effects in Phosphino-Iminophosphorane Pd II Complexes upon Varying the N Substituent. Chemistry 2024; 30:e202303350. [PMID: 37872737 DOI: 10.1002/chem.202303350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 10/20/2023] [Accepted: 10/23/2023] [Indexed: 10/25/2023]
Abstract
Three series of palladium(II) complexes supported by a phosphine-iminophosphorane ligand built upon an ortho-phenylene core were investigated to study the influence of the iminophosphorane N substituent. Cis-dichloride palladium(II) complexes 1 in which the N atom bears an isopropyl (iPr, 1 a), a phenyl (Ph, 1 b), a trimethylsilyl (TMS, 1 c) group or an H atom (1 d) were synthesized in high yield. They were characterized by NMR, IR spectroscopy, HR-mass spectrometry, elemental analysis, and X-ray diffraction. A substantial bond length difference between the Pd-Cl bonds was observed in 1. Complexes 1 a-d were converted into [Pd(LR )Cl(CNt Bu)](OTf)] 2 a-d whose isocyanide is located trans to the iminophosphorane. The corresponding dicationic complexes [Pd(LR )(CNt Bu)2 ](OTf)2 3 a-d were also synthesized, however they exhibited lower stability in solution than 2, the isopropyl derivative 3 a being the most stable of the series. Molecular modeling was performed to rationalize the regioselectivity of the substitution of the single chloride by isocyanide (from 1 to 2) and to study the electronic distribution in the complexes. In particular differences between the TMS and H containing complexes vs. the iPr and Ph ones were found. This suggests that the nature of the N substituent is far from innocent and can help tune the reactivity of iminophosphorane complexes.
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Affiliation(s)
- Ingrid Popovici
- Laboratoire de Chimie Moléculaire (LCM), CNRS, École Polytechnique, Institut Polytechnique de Paris, Route de Saclay, 91120, Palaiseau, France
| | - Elise Lognon
- ITODYS, Université Paris Cité and CNRS, 75006, Paris, France
| | - Nicolas Casaretto
- Laboratoire de Chimie Moléculaire (LCM), CNRS, École Polytechnique, Institut Polytechnique de Paris, Route de Saclay, 91120, Palaiseau, France
| | - Antonio Monari
- ITODYS, Université Paris Cité and CNRS, 75006, Paris, France
| | - Audrey Auffrant
- Laboratoire de Chimie Moléculaire (LCM), CNRS, École Polytechnique, Institut Polytechnique de Paris, Route de Saclay, 91120, Palaiseau, France
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12
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Cai Y, Zhao Y, Tang K, Zhang H, Mo X, Chen J, Huang Y. Amide C-N bonds activation by A new variant of bifunctional N-heterocyclic carbene. Nat Commun 2024; 15:496. [PMID: 38216571 PMCID: PMC10786861 DOI: 10.1038/s41467-024-44756-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 01/03/2024] [Indexed: 01/14/2024] Open
Abstract
We report an organocatalyst that combines a triazolium N-heterocyclic carbene (NHC) with a squaramide as a hydrogen-bonding donor (HBD), which can effectively catalyze the atroposelective ring-opening of biaryl lactams via a unique amide C-N bond cleavage mode. The free carbene species attacks the amide carbonyl, forming an axially chiral acyl-azolium intermediate. Various axially chiral biaryl amines can be accessed by this methodology with up to 99% ee and 99% yield. By using mercaptan as a catalyst turnover agent, the resulting thioester synthon can be transformed into several interesting atropisomers. Both control experiments and theoretical calculations reveal the crucial role of the hybrid NHC-HBD skeleton, which activates the amide via H-bonding and brings it spatially close to the carbene centre. This discovery illustrates the potential of the NHC-HBD chimera and demonstrates a complementary strategy for amide bond activation and manipulation.
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Affiliation(s)
- Yuxing Cai
- State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, 518055, Shenzhen, China
- Pingshan Translational Medicine Center, Shenzhen Bay Laboratory, 518118, Shenzhen, China
| | - Yuxin Zhao
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China
| | - Kai Tang
- Pingshan Translational Medicine Center, Shenzhen Bay Laboratory, 518118, Shenzhen, China
| | - Hong Zhang
- Pingshan Translational Medicine Center, Shenzhen Bay Laboratory, 518118, Shenzhen, China
| | - Xueling Mo
- Pingshan Translational Medicine Center, Shenzhen Bay Laboratory, 518118, Shenzhen, China
| | - Jiean Chen
- Pingshan Translational Medicine Center, Shenzhen Bay Laboratory, 518118, Shenzhen, China.
| | - Yong Huang
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, China.
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13
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Miller AAM, Biallas P, Shennan BDA, Dixon DJ. Enantioselective Total Synthesis of (+)-Incargranine A Enabled by Bifunctional Iminophosphorane and Iridium Catalysis. Angew Chem Int Ed Engl 2024; 63:e202314308. [PMID: 37955594 DOI: 10.1002/anie.202314308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2023] [Revised: 11/08/2023] [Accepted: 11/10/2023] [Indexed: 11/14/2023]
Abstract
Herein we report the first enantioselective total synthesis of (+)-incargranine A, in nine steps. The total synthesis was enabled by an enantioselective intramolecular organocatalysed desymmetrising Michael addition of a malonamate ester to a linked dienone substrate that established pivotal stereocentres with excellent enantio- and complete diastereoselectivity. Furthermore, a key hemiaminal intermediate was accessed by developing an iridium-catalysed reductive cyclisation, and the scope of this transformation was explored to produce a range of bicyclic hemiaminal motifs. Once installed, the hemiaminal motif was used to initiate a biomimetic cascade to access the natural product directly in a single step.
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Affiliation(s)
- Anna A M Miller
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Phillip Biallas
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Benjamin D A Shennan
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
| | - Darren J Dixon
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford, OX1 3TA, UK
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14
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Poh CYX, Rozsar D, Yang J, Christensen KE, Dixon DJ. Bifunctional Iminophosphorane Catalyzed Amide Enolization for Enantioselective Cyclohexadienone Desymmetrization. Angew Chem Int Ed Engl 2023:e202315401. [PMID: 38055190 DOI: 10.1002/anie.202315401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 11/29/2023] [Accepted: 11/30/2023] [Indexed: 12/07/2023]
Abstract
The organocatalytic enolization of 2-arylacetamides, followed by an enantioselective intramolecular conjugate addition to tethered 2,5-cyclohexadienones, yielding 3D fused N-heterocycles, is described. The transformation represents the first strong activating group-free activation of carboxamides via α-C-H deprotonation in a metal-free, catalytic, and enantioselective reaction, and is achieved by employing a bifunctional iminophosphorane (BIMP) superbase.
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Affiliation(s)
- Charmaine Y X Poh
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford, UK
| | - Daniel Rozsar
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford, UK
| | - Jinchao Yang
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford, UK
| | - Kirsten E Christensen
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford, UK
| | - Darren J Dixon
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford, UK
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15
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Budeev A, Dong J, Häussinger D, Sparr C. Catalyst control over pentavalent stereocentres. Nat Commun 2023; 14:8013. [PMID: 38049395 PMCID: PMC10696079 DOI: 10.1038/s41467-023-43750-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Accepted: 11/17/2023] [Indexed: 12/06/2023] Open
Abstract
A monumental diversity of catalytic methods imparts the ability to select one of two configurations of tetravalent stereocentres. Conversely, catalyst control over pentavalent stereocentres, where a fifth moiety bound to the central atom encodes an expanded stereochemical space, remained a challenge to be accomplished. Herein, we report the feasibility of the catalytic tractability of pentavalent stereocentres. A bifunctional iminophosphorane thiourea catalyst enables enantio- and diastereocontrol over pentavalent phosphoranes to differentiate configurationally stable enantiomers and ensembles of diastereomers which emerge together from a single stereocentre. The desired dioxophosphorane stereoisomers are obtained with excellent yield and selectivity (up to 99% yield, 96:4 e.r. and 99:1 d.r.), while stereodivergent catalysis reroutes the reaction for selective access to each of the viable stereoisomeric states of pentavalent phosphoranes. Considering the diversity of high-valent main group species, it is expected that catalyst control over pentavalent stereocentres significantly increases the synthetically addressable stereochemical space.
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Affiliation(s)
- Anton Budeev
- Department of Chemistry, University of Basel, Basel, Switzerland
| | - Jianyang Dong
- Department of Chemistry, University of Basel, Basel, Switzerland
| | | | - Christof Sparr
- Department of Chemistry, University of Basel, Basel, Switzerland.
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16
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Oiarbide M, Palomo C. Brønsted Base-Catalyzed Enantioselective α-Functionalization of Carbonyl Compounds Involving π-Extended Enolates. CHEM REC 2023; 23:e202300164. [PMID: 37350363 DOI: 10.1002/tcr.202300164] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 06/06/2023] [Indexed: 06/24/2023]
Abstract
Chiral Brønsted base (BB) catalyzed asymmetric transformations constitute an important tool for synthesis. A meaningful fraction of these transformations proceeds through transiently generated enolate intermediates, which display quite versatile reactivity against a variety of electrophiles. Some years ago, our group became interested in developing BB-catalyzed asymmetric reactions of enolizable carbonyl substrates that involve π-extended enolates in which, besides control of reaction diastereo and enantioselectivity, the site-selectivity control is an additional issue in most cases. In the examples covered in this account the opportunities deployed, and the challenges posed, by these methods are illustrated, with a focus on the generation of quaternary carbon stereocenters. In the way, new bifunctional BB catalysts as well as achiral templates were developed that may find further applications.
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Affiliation(s)
- Mikel Oiarbide
- Departamento de Química Orgánica I, Universidad del País Vasco UPV/EHU, Manuel Lardizabal 3, 20018 San Sebastián, Spain
| | - Claudio Palomo
- Departamento de Química Orgánica I, Universidad del País Vasco UPV/EHU, Manuel Lardizabal 3, 20018 San Sebastián, Spain
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17
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Ye M, Xu Y, Song T, Gao Z. NbCl 5-catalyzed sulfa-Michael addition for constructing quaternary centers in enones. Org Biomol Chem 2023; 21:7100-7105. [PMID: 37526152 DOI: 10.1039/d3ob00911d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
A novel NbCl5-catalyzed sulfa-conjugate addition has been developed to construct quaternary centers in various enones. This new method enables a range of functionalized thiols to access different β-sulfido carbonyl compounds bearing a quaternary center. 27 novel β-sulfido ketones have been obtained with moderate to excellent yields. The preparative scale reactions also proceed well, showing no decrease in yield. We further studied the mechanism by DFT calculations. This methodology is significant in sulfur chemistry, especially in sulfa-conjugate addition, giving a new pathway to add thiols to tri-substituted enones.
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Affiliation(s)
- Mingxia Ye
- Jiangsu Key Laboratory of Pesticide Science and Department of Chemistry, College of Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, China.
| | - Yingying Xu
- Jiangsu Key Laboratory of Pesticide Science and Department of Chemistry, College of Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, China.
| | - Tianhang Song
- Shijiazhuang Tianhang Science & Technology Co., Ltd., Shijiazhuang, Hebei, China.
| | - Zhenbo Gao
- Jiangsu Key Laboratory of Pesticide Science and Department of Chemistry, College of Sciences, Nanjing Agricultural University, Nanjing, Jiangsu, China.
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18
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Cassels WR, Johnson JS. Development of organic reactions that productively leverage physical properties. SCIENCE ADVANCES 2023; 9:eadg6765. [PMID: 37406122 PMCID: PMC10321729 DOI: 10.1126/sciadv.adg6765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 06/01/2023] [Indexed: 07/07/2023]
Abstract
Crystallization-induced stereoconvergent Michael additions demonstrate the potential of using physical properties to reveal unique reactivity.
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Affiliation(s)
- William R. Cassels
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jeffrey S. Johnson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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19
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Giordano MT, Kitzinger KM, de Jesús Cruz P, Liu S, Johnson JS. Catalytic, Asymmetric Michael-Aldol Annulations via a Stereodivergent/Stereoconvergent Path Operating under Curtin-Hammett Control. J Am Chem Soc 2023; 145:12370-12376. [PMID: 37216269 PMCID: PMC10360212 DOI: 10.1021/jacs.3c03373] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A bifunctional iminophosphorane (BIMP)-catalyzed method for the synthesis of densely functionalized cyclohexanols establishes five contiguous stereocenters (diastereoselection up to >20:1, enantioselectivity up to >99:1) in a Michael/aldol domino reaction between trisubstituted electrophilic alkenes and γ-nitroketones. Mechanistic studies suggest a scenario in which stereoconvergency is achieved by kinetically controlled cyclization after the initial diastereodivergent Michael addition. Diastereoconvergency during cyclization is shown to result from Curtin-Hammett kinetics, a finding that contrasts the crystallization-driven stereoconvergency previously reported in similar systems. Despite the change in the stereocontrol mechanism, the operational attributes remain attractive, with the crystalline products typically isolated in analytically pure form upon filtration of the reaction mixture.
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Affiliation(s)
- Mitchell T Giordano
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Katelyn M Kitzinger
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Pedro de Jesús Cruz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Shubin Liu
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
- Research Computing Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Jeffrey S Johnson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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20
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Rozsar D, Farley AJM, McLauchlan I, Shennan BDA, Yamazaki K, Dixon DJ. Bifunctional Iminophosphorane-Catalyzed Enantioselective Nitroalkane Addition to Unactivated α,β-Unsaturated Esters. Angew Chem Int Ed Engl 2023; 62:e202303391. [PMID: 36929179 PMCID: PMC10946890 DOI: 10.1002/anie.202303391] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 03/14/2023] [Accepted: 03/15/2023] [Indexed: 03/18/2023]
Abstract
Herein we describe the enantioselective intermolecular conjugate addition of nitroalkanes to unactivated α,β-unsaturated esters, catalyzed by a bifunctional iminophosphorane (BIMP) superbase. The transformation provides the most direct access to pharmaceutically relevant enantioenriched γ-nitroesters, utilizing feedstock chemicals, with unprecedented selectivity. The methodology exhibits a broad substrate scope, including β-(fluoro)alkyl, aryl and heteroaryl substituted electrophiles, and was successfully applied on a gram scale with reduced catalyst loading, and, additionally, catalyst recovery was carried out. The formal synthesis of a range of drug molecules, and an enantioselective synthesis of (S)-rolipram were achieved. Additionally, computational studies revealed key reaction intermediates and transition state structures, and provided rationale for high enantioselectivities, in good agreement with experimental results.
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Affiliation(s)
- Daniel Rozsar
- Department of ChemistryUniversity of OxfordChemistry Research LaboratoryOX1 3TAOxfordUK
| | - Alistair J. M. Farley
- Department of ChemistryUniversity of OxfordChemistry Research LaboratoryOX1 3TAOxfordUK
| | - Iain McLauchlan
- Department of ChemistryUniversity of OxfordChemistry Research LaboratoryOX1 3TAOxfordUK
| | | | - Ken Yamazaki
- Division of Applied ChemistryOkayama University700-8530TsushimanakaOkayamaJapan
| | - Darren J. Dixon
- Department of ChemistryUniversity of OxfordChemistry Research LaboratoryOX1 3TAOxfordUK
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21
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Formica M, Rogova T, Shi H, Sahara N, Ferko B, Farley AJM, Christensen KE, Duarte F, Yamazaki K, Dixon DJ. Catalytic enantioselective nucleophilic desymmetrization of phosphonate esters. Nat Chem 2023; 15:714-721. [PMID: 37127757 PMCID: PMC10159838 DOI: 10.1038/s41557-023-01165-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 02/20/2023] [Indexed: 05/03/2023]
Abstract
Molecules that contain a stereogenic phosphorus atom are crucial to medicine, agrochemistry and catalysis. While methods are available for the selective construction of various chiral organophosphorus compounds, catalytic enantioselective approaches for their synthesis are far less common. Given the vastness of possible substituent combinations around a phosphorus atom, protocols for their preparation should also be divergent, providing facile access not only to one but to many classes of phosphorus compounds. Here we introduce a catalytic and enantioselective strategy for the preparation of an enantioenriched phosphorus(V) centre that can be diversified enantiospecifically to a wide range of biologically relevant phosphorus(V) compounds. The process, which involves an enantioselective nucleophilic substitution catalysed by a superbasic bifunctional iminophosphorane catalyst, can accommodate a wide range of carbon substituents at phosphorus. The resulting stable, yet versatile, synthetic intermediates can be combined with a multitude of medicinally relevant O-, N- and S-based nucleophiles.
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Affiliation(s)
- Michele Formica
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK
| | - Tatiana Rogova
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK
| | - Heyao Shi
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK
| | - Naoto Sahara
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK
- Graduate School of Engineering, Nagoya University, Nagoya, Japan
| | - Branislav Ferko
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK
| | - Alistair J M Farley
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK
| | - Kirsten E Christensen
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK
| | - Fernanda Duarte
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK
| | - Ken Yamazaki
- Division of Applied Chemistry, Okayama University, Okayama, Japan.
| | - Darren J Dixon
- Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford, UK.
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22
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Falk E, Franchino A, Horak T, Gürtler L, Morandi B. Azide-Free Synthesis of N-Alkyliminophosphoranes from Phosphines and Hydroxylamine Derivatives. Org Lett 2023; 25:1695-1700. [PMID: 36926926 DOI: 10.1021/acs.orglett.3c00366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
Abstract
A broadly applicable and efficient method for the synthesis of N-alkyliminophosphoranes from phosphines that does not use potentially hazardous alkyl azides is reported. Under iron catalysis, a hydroxylamine-derived triflic acid salt oxidizes phosphines to a wide range of iminophosphorane triflic acid salts. Diphosphines afford phosphine-iminophosphoranes that can serve as ligands in transition metal complexes. The developed method can be employed in the synthesis of mixed diiminophosphoranes and in a traceless Staudinger ligation.
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Affiliation(s)
- Eric Falk
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland
| | - Allegra Franchino
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland
| | - Teresa Horak
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland
| | - Laura Gürtler
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland
| | - Bill Morandi
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland
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23
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Sorensen CC, Kozuszek CT, Borden MA, Leibfarth FA. Asymmetric Ion-Pairing in Stereoselective Vinyl Polymerization. ACS Catal 2023. [DOI: 10.1021/acscatal.3c00040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Affiliation(s)
- Cole C. Sorensen
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Caleb T. Kozuszek
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Meredith A. Borden
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
| | - Frank A. Leibfarth
- Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, United States
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24
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Gallarati S, van Gerwen P, Laplaza R, Vela S, Fabrizio A, Corminboeuf C. OSCAR: an extensive repository of chemically and functionally diverse organocatalysts. Chem Sci 2022; 13:13782-13794. [PMID: 36544722 PMCID: PMC9710326 DOI: 10.1039/d2sc04251g] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 10/24/2022] [Indexed: 12/24/2022] Open
Abstract
The automated construction of datasets has become increasingly relevant in computational chemistry. While transition-metal catalysis has greatly benefitted from bottom-up or top-down strategies for the curation of organometallic complexes libraries, the field of organocatalysis is mostly dominated by case-by-case studies, with a lack of transferable data-driven tools that facilitate both the exploration of a wider range of catalyst space and the optimization of reaction properties. For these reasons, we introduce OSCAR, a repository of 4000 experimentally derived organocatalysts along with their corresponding building blocks and combinatorially enriched structures. We outline the fragment-based approach used for database generation and showcase the chemical diversity, in terms of functions and molecular properties, covered in OSCAR. The structures and corresponding stereoelectronic properties are publicly available (https://archive.materialscloud.org/record/2022.106) and constitute the starting point to build generative and predictive models for organocatalyst performance.
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Affiliation(s)
- Simone Gallarati
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL)1015 LausanneSwitzerland
| | - Puck van Gerwen
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL)1015 LausanneSwitzerland,National Center for Competence in Research – Catalysis (NCCR-Catalysis), Ecole Polytechnique Fédérale de Lausanne (EPFL)1015 LausanneSwitzerland
| | - Ruben Laplaza
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL)1015 LausanneSwitzerland,National Center for Competence in Research – Catalysis (NCCR-Catalysis), Ecole Polytechnique Fédérale de Lausanne (EPFL)1015 LausanneSwitzerland
| | - Sergi Vela
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL)1015 LausanneSwitzerland
| | - Alberto Fabrizio
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL)1015 LausanneSwitzerland,National Center for Computational Design and Discovery of Novel Materials (MARVEL), Ecole Polytechnique Fédérale de Lausanne (EPFL)1015 LausanneSwitzerland
| | - Clemence Corminboeuf
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL)1015 LausanneSwitzerland,National Center for Competence in Research – Catalysis (NCCR-Catalysis), Ecole Polytechnique Fédérale de Lausanne (EPFL)1015 LausanneSwitzerland,National Center for Computational Design and Discovery of Novel Materials (MARVEL), Ecole Polytechnique Fédérale de Lausanne (EPFL)1015 LausanneSwitzerland
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25
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Fritz-Langhals E. Unique Superbase TBD (1,5,7-Triazabicyclo[4.4.0]dec-5-ene): From Catalytic Activity and One-Pot Synthesis to Broader Application in Industrial Chemistry. Org Process Res Dev 2022. [DOI: 10.1021/acs.oprd.2c00248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Elke Fritz-Langhals
- Department of Chemistry, Technical University of Munich (TUM), Lichtenbergstraße 4, D-85747 Garching, Germany
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26
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Affiliation(s)
- Son H. Doan
- School of Chemistry, University of New South Wales, Sydney 2052, New South Wales, Australia
| | - Nhan N. H. Ton
- School of Chemistry, University of New South Wales, Sydney 2052, New South Wales, Australia
| | - Binh Khanh Mai
- Department of Chemistry, University of Pittsburgh, Pittsburgh 15260, Pennsylvania, United States
| | - Thanh Vinh Nguyen
- School of Chemistry, University of New South Wales, Sydney 2052, New South Wales, Australia
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27
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Nie W, Liu D, Li S, Yu H, Fu Y. Nucleophilicity Prediction Using Graph Neural Networks. J Chem Inf Model 2022; 62:4319-4328. [PMID: 36097394 DOI: 10.1021/acs.jcim.2c00696] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The quantitative description between chemical reaction rates and nucleophilicity parameters plays a crucial role in organic chemistry. In this regard, the formula proposed by Mayr et al. and the constructed reactivity database are important representatives. However, the determination of Mayr's nucleophilicity parameter N often requires time-consuming experiments with reference electrophiles in the solvent. Several machine learning (ML)-based models have been proposed to realize the data-driven prediction of N in recent years. However, in addition to DFT-calculated electronic descriptors, most of them also use a set of artificially predefined structural descriptors as input, which may result in a biased representation of the nucleophile's structural information depending on descriptors' definition preference. Compared with traditional ML algorithms, graph neural networks (GNNs) can naturally take the molecule's structural information into account by applying the message passing technique. We herein proposed a SchNet-based GNN model that only takes the molecular conformation and solvent type as input. The model achieves a comparable performance to the previous benchmark study on 10-fold cross-validation of 894 data points (R2 = 0.91, RMSE = 2.25). To enhance the model's ability to capture the molecule's electronic information, some DFT-calculated parameters are then incorporated into the model via graph global features, and substantial improvement is achieved in the prediction precision (R2 = 0.95, RMSE = 1.63). These results demonstrate that both structural and electronic information are important for the prediction of N, and GNN can integrate these two kinds of information more effectively.
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Affiliation(s)
- Wan Nie
- Hefei National Laboratory for Physical Sciences at the Microscale, CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Center for Excellence in Molecular Synthesis of CAS, Institute of Energy, Hefei Comprehensive National Science Center, University of Science and Technology of China, Hefei 230026, China.,Department of Computer Science, City University of Hong Kong, Hong Kong 999077, China
| | - Deguang Liu
- Hefei National Laboratory for Physical Sciences at the Microscale, CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Center for Excellence in Molecular Synthesis of CAS, Institute of Energy, Hefei Comprehensive National Science Center, University of Science and Technology of China, Hefei 230026, China
| | - Shuaicheng Li
- Department of Computer Science, City University of Hong Kong, Hong Kong 999077, China
| | - Haizhu Yu
- Department of Chemistry and Centre for Atomic Engineering of Advanced Materials, Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials, Anhui University, Hefei 230601, China
| | - Yao Fu
- Hefei National Laboratory for Physical Sciences at the Microscale, CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, Center for Excellence in Molecular Synthesis of CAS, Institute of Energy, Hefei Comprehensive National Science Center, University of Science and Technology of China, Hefei 230026, China
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28
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De Jesús Cruz P, Johnson JS. Crystallization-Enabled Henry Reactions: Stereoconvergent Construction of Fully Substituted [ N]-Asymmetric Centers. J Am Chem Soc 2022; 144:15803-15811. [PMID: 35980759 PMCID: PMC9469918 DOI: 10.1021/jacs.2c06669] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Tetrasubstituted stereogenic carbon centers bearing a nitrogen substituent represent important motifs in medicinal chemistry and natural products; therefore, the development of efficient methods for the stereoselective synthesis of this class of compounds continues to be an important problem. This article describes stereoconvergent Henry reactions of γ,γ-disubstituted nitroalkanes to deliver highly functionalized building blocks containing up to five contiguous stereogenic centers including a fully substituted [N]-asymmetric center. Henry reactions of higher order nitroalkanes are often characterized by their reversibility and minimal accompanying thermodynamic stereocontrol. In contrast, mechanistic studies for the present case suggest a scenario in which reversibility is productively leveraged through crystallization-based stereocontrol, thereby enabling the efficient sequential π-additions of readily accessible starting materials to assemble complex acyclic stereoarrays.
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Affiliation(s)
- Pedro De Jesús Cruz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
| | - Jeffrey S Johnson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3290, United States
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29
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Han W, Su J, Mo JN, Zhao J. Photoredox Catalytic Phosphine-Mediated Deoxygenation of Hydroxylamines Enables the Construction of N-Acyliminophosphoranes. Org Lett 2022; 24:6247-6251. [PMID: 35998322 DOI: 10.1021/acs.orglett.2c02226] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The chemistry of phosphoranyl radicals has received increasing attention in recent years. Here, we report the generation of amidyl radicals through photocatalytic deoxygenation of hydroxylamines with triphenylphosphine. This methodology offers a novel and convenient route to a diverse range of N-acyliminophosphoranes in moderate to good yields under visible-light photoredox conditions. Fluorescence quenching experiments suggest that the excited-state of the organic photocatalyst (4CzIPN) was oxidatively quenched by a Cu(II) salt.
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Affiliation(s)
- Wencheng Han
- Zhang Dayu School of Chemistry, Dalian University of Technology, Dalian 116024, P. R. China
| | - Junqi Su
- Zhang Dayu School of Chemistry, Dalian University of Technology, Dalian 116024, P. R. China
| | - Jia-Nan Mo
- Zhang Dayu School of Chemistry, Dalian University of Technology, Dalian 116024, P. R. China
| | - Jiannan Zhao
- Zhang Dayu School of Chemistry, Dalian University of Technology, Dalian 116024, P. R. China
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30
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Joseph D, Lee S. Reaction of Amide and Sodium Azide for the Synthesis of Acyl Azide, Urea, and Iminophosphorane. Org Lett 2022; 24:6186-6191. [PMID: 35959978 DOI: 10.1021/acs.orglett.2c02429] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Amides reacted with NaN3 to give the acyl azides in DMF at 25 °C and produce the symmetrical ureas in THF/H2O at 80 °C via the sequential reaction of acyl substitution and Curtius rearrangement. All acyl azides were also obtained from the secondary amides via sequential reaction of p-toluenesulfonyl chloride and NaN3. In addition, keto-stabilized iminophosphoranes were prepared from a one-pot reaction of amides, NaN3, and phosphines.
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Affiliation(s)
- Devaneyan Joseph
- Department of Chemistry, Chonnam National University, Gwangju, 61186, Republic of Korea
| | - Sunwoo Lee
- Department of Chemistry, Chonnam National University, Gwangju, 61186, Republic of Korea
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31
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Lee HB, Britt RD, Rittle J. N − H bond dissociation free energy of a terminal iron phosphinimine. J COORD CHEM 2022. [DOI: 10.1080/00958972.2022.2103411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
Affiliation(s)
- Heui Beom Lee
- Department of Chemistry, University of California Berkeley, Berkeley, CA, USA
| | - R. David Britt
- Department of Chemistry, University of California Davis, Davis, CA, USA
| | - Jonathan Rittle
- Department of Chemistry, University of California Berkeley, Berkeley, CA, USA
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32
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Ben Hamouda K, Kanzari-Mnallah D, Ben Ali R, Bechaieb R, Efrit ML, May MVE, Akacha AB. Iminophosphoranes: Synthesis, evolution of synthesis by 31P-NMR, DFT calculations and antioxidant activity. PHOSPHORUS SULFUR 2022. [DOI: 10.1080/10426507.2022.2085273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Kaouther Ben Hamouda
- Laboratory of Selective Organic & Heterocyclic Synthesis Biological Activity Evaluation (LR17ES01), Department of Chemistry, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Dorra Kanzari-Mnallah
- Laboratory of Selective Organic & Heterocyclic Synthesis Biological Activity Evaluation (LR17ES01), Department of Chemistry, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Ridha Ben Ali
- Experimental Medicine Unit, Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Rim Bechaieb
- Laboratory of Selective Organic & Heterocyclic Synthesis Biological Activity Evaluation (LR17ES01), Department of Chemistry, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis, Tunisia
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, UMR 7616, Laboratoire de Chimie Théorique, Paris, France
| | - Mohamed Lotfi Efrit
- Laboratory of Selective Organic & Heterocyclic Synthesis Biological Activity Evaluation (LR17ES01), Department of Chemistry, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Michèle Véronique El May
- Experimental Medicine Unit, Faculty of Medicine of Tunis, University of Tunis El Manar, Tunis, Tunisia
| | - Azaiez Ben Akacha
- Laboratory of Selective Organic & Heterocyclic Synthesis Biological Activity Evaluation (LR17ES01), Department of Chemistry, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis, Tunisia
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33
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de Jesús Cruz P, Cassels WR, Chen CH, Johnson JS. Doubly stereoconvergent crystallization enabled by asymmetric catalysis. Science 2022; 376:1224-1230. [PMID: 35679416 DOI: 10.1126/science.abo5048] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Synthetic methods that enable simultaneous control over multiple stereogenic centers are desirable for the efficient preparation of pharmaceutical compounds. Herein, we report the discovery and development of a catalyst-mediated asymmetric Michael addition/crystallization-induced diastereomer transformation of broad scope. The sequence controls three stereogenic centers, two of which are stereochemically labile. The configurational instability of 1,3-dicarbonyls and nitroalkanes, typically considered a liability in stereoselective synthesis, is productively leveraged by merging enantioselective Brønsted base organocatalysis and thermodynamic stereocontrol using a single convergent crystallization. The synthesis of useful γ-nitro β-keto amides containing three contiguous stereogenic centers is thus achieved from Michael acceptors containing two prochiral centers.
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Affiliation(s)
- Pedro de Jesús Cruz
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - William R Cassels
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Chun-Hsing Chen
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Jeffrey S Johnson
- Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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34
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Lin S, Lin B, Zhang Z, Chen J, Luo Y, Xia Y. Construction of N-Acyliminophosphoranes via Iron(II)-Catalyzed Imidization of Phosphines with N-Acyloxyamides. Org Lett 2022; 24:3302-3306. [PMID: 35468280 DOI: 10.1021/acs.orglett.2c01238] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Employing FeCl2 as a cheap and readily available catalyst, a facile imidization of phosphines with N-acyloxyamides is described, affording synthetically useful N-acyliminophosphoranes with high functional group tolerance. The transformation is easily performed under an air atmosphere at room temperature and could be scaled up to gram scale with a catalyst loading of 1 mol %. The iminophosphoranyl moiety in the product was further utilized as an effective directing group for controllable ortho C(sp2)-H bond amidations under Rh(III) catalysis.
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Affiliation(s)
- Sen Lin
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China
| | - Bo Lin
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China
| | - Zongtao Zhang
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China
| | - Jianhui Chen
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China
| | - Yanshu Luo
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China
| | - Yuanzhi Xia
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China
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35
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Bai YJ, Cheng ML, Zheng XH, Zhang SY, Wang PA. Chiral Cyclopropenimine-catalyzed Asymmetric Michael Addition of Bulky Glycine Imine to α,β-Unsaturated Isoxazoles. Chem Asian J 2022; 17:e202200131. [PMID: 35415949 DOI: 10.1002/asia.202200131] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/26/2022] [Indexed: 11/11/2022]
Abstract
A highly efficient asymmetric Michael addition of bulky glycine imine to α,β-unsaturated isoxazoles has been achieved by using 5 mol% of chiral cyclopropenimine as a chiral organo-superbase catalyst under mild conditions. Michael adducts were obtained in excellent yields (up to 97%) and stereoselectivities (up to>99 : 1 dr and 98% ee). A significant solvent effect was found in these chiral organosuperbase catalyzed asymmetric Michael reactions. Gram-scale preparation of Michael adducts and their transformations are realized to provide corresponding products without loss of stereoselectivities. The configurations of Michael adduct was determined by single-crystal X-ray diffraction analysis.
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Affiliation(s)
- Yu-Jun Bai
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, The College of Life Sciences, Northwest University, Xi'an, 710069, P. R. China) E-mails.,Department of Medicinal Chemistry and Pharmaceutical Analysis, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, P. R. China
| | - Mei-Ling Cheng
- Department of Medicinal Chemistry and Pharmaceutical Analysis, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, P. R. China
| | - Xiao-Hui Zheng
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, The College of Life Sciences, Northwest University, Xi'an, 710069, P. R. China) E-mails
| | - Sheng-Yong Zhang
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, The College of Life Sciences, Northwest University, Xi'an, 710069, P. R. China) E-mails.,Department of Medicinal Chemistry and Pharmaceutical Analysis, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, P. R. China
| | - Ping-An Wang
- Department of Medicinal Chemistry and Pharmaceutical Analysis, School of Pharmacy, Fourth Military Medical University, Xi'an, 710032, P. R. China
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36
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Rozsar D, Formica M, Yamazaki K, Hamlin TA, Dixon DJ. Bifunctional Iminophosphorane-Catalyzed Enantioselective Sulfa-Michael Addition to Unactivated α,β-Unsaturated Amides. J Am Chem Soc 2022; 144:1006-1015. [PMID: 34990142 PMCID: PMC8793149 DOI: 10.1021/jacs.1c11898] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
![]()
The
first metal-free catalytic intermolecular enantioselective
Michael addition to unactivated α,β-unsaturated amides
is described. Consistently high enantiomeric excesses and yields were
obtained over a wide range of alkyl thiol pronucleophiles and electrophiles
under mild reaction conditions, enabled by a novel squaramide-based
bifunctional iminophosphorane catalyst. Low catalyst loadings (2.0
mol %) were achieved on a decagram scale, demonstrating the scalability
of the reaction. Computational analysis revealed the origin of the
high enantiofacial selectivity via analysis of relevant transition
structures and provided substantial support for specific noncovalent
activation of the carbonyl group of the α,β-unsaturated
amide by the catalyst.
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Affiliation(s)
- Daniel Rozsar
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, OX1 3TA Oxford, United Kingdom
| | - Michele Formica
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, OX1 3TA Oxford, United Kingdom
| | - Ken Yamazaki
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, OX1 3TA Oxford, United Kingdom.,Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Trevor A Hamlin
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
| | - Darren J Dixon
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, OX1 3TA Oxford, United Kingdom
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37
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Tukhtaev HB, Bezzubov SI, Tarasenko EA, Melnikov MY, Ivanov KL, Budynina EM. Time‐Dependent Diastereodivergent Michael Addition Enabled by Phosphazenes Acting as Catalysts and Reactants. Adv Synth Catal 2021. [DOI: 10.1002/adsc.202100570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Hamidulla B. Tukhtaev
- Lomonosov Moscow State University Department of Chemistry Leninskie gory 1–3 Moscow 119991 Russia
| | - Stanislav I. Bezzubov
- Kurnakov Institute of General and Inorganic Chemistry Russian Academy of Sciences Leninskiy pr. 31 Moscow 119991 Russia
| | - Elena A. Tarasenko
- Lomonosov Moscow State University Department of Chemistry Leninskie gory 1–3 Moscow 119991 Russia
| | - Mikhail Ya. Melnikov
- Lomonosov Moscow State University Department of Chemistry Leninskie gory 1–3 Moscow 119991 Russia
| | - Konstantin L. Ivanov
- Lomonosov Moscow State University Department of Chemistry Leninskie gory 1–3 Moscow 119991 Russia
| | - Ekaterina M. Budynina
- Lomonosov Moscow State University Department of Chemistry Leninskie gory 1–3 Moscow 119991 Russia
- Lebedev Physical Institute Russian Academy of Sciences Leninskiy pr. 53 Moscow 119991 Russia
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38
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Vermersch F, Yazdani S, Junor GP, Grotjahn DB, Jazzar R, Bertrand G. Stable Singlet Carbenes as Organic Superbases. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202111588] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- François Vermersch
- UCSD-CNRS Joint Research Laboratory (IRL 3555) Department of Chemistry and Biochemistry University of California San Diego, La Jolla CA 92093-0358 USA
| | - Sima Yazdani
- UCSD-CNRS Joint Research Laboratory (IRL 3555) Department of Chemistry and Biochemistry University of California San Diego, La Jolla CA 92093-0358 USA
- Department of Chemistry and Biochemistry San Diego State University 5500 Campanile Drive San Diego CA 92182-1030 USA
| | - Glen P. Junor
- UCSD-CNRS Joint Research Laboratory (IRL 3555) Department of Chemistry and Biochemistry University of California San Diego, La Jolla CA 92093-0358 USA
| | - Douglas B. Grotjahn
- Department of Chemistry and Biochemistry San Diego State University 5500 Campanile Drive San Diego CA 92182-1030 USA
| | - Rodolphe Jazzar
- UCSD-CNRS Joint Research Laboratory (IRL 3555) Department of Chemistry and Biochemistry University of California San Diego, La Jolla CA 92093-0358 USA
| | - Guy Bertrand
- UCSD-CNRS Joint Research Laboratory (IRL 3555) Department of Chemistry and Biochemistry University of California San Diego, La Jolla CA 92093-0358 USA
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39
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Vermersch F, Yazdani S, Junor GP, Grotjahn DB, Jazzar R, Bertrand G. Stable Singlet Carbenes as Organic Superbases. Angew Chem Int Ed Engl 2021; 60:27253-27257. [PMID: 34729888 DOI: 10.1002/anie.202111588] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/18/2021] [Indexed: 11/10/2022]
Abstract
A simple experimental procedure for scaling carbene Brønsted basicity is described. The results highlight the strong basicity of pyrazol-4-ylidenes, a type of mesoionic carbene, also named cyclic-bentallenes (CBA). They are more basic (pKaH >42.7 in acetonitrile) than the popular proazaphosphatrane Verkade bases, and even the Schwesinger phosphazene superbase P4 (t Bu). The basicity of these compounds can readily be tuned, and they are accessible in multigram quantities. These results open new avenues for carbon centered superbases.
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Affiliation(s)
- François Vermersch
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA
| | - Sima Yazdani
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA.,Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Drive, San Diego, CA, 92182-1030, USA
| | - Glen P Junor
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA
| | - Douglas B Grotjahn
- Department of Chemistry and Biochemistry, San Diego State University, 5500 Campanile Drive, San Diego, CA, 92182-1030, USA
| | - Rodolphe Jazzar
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA
| | - Guy Bertrand
- UCSD-CNRS Joint Research Laboratory (IRL 3555), Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA, 92093-0358, USA
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40
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Vazdar K, Margetić D, Kovačević B, Sundermeyer J, Leito I, Jahn U. Design of Novel Uncharged Organic Superbases: Merging Basicity and Functionality. Acc Chem Res 2021; 54:3108-3123. [PMID: 34308625 DOI: 10.1021/acs.accounts.1c00297] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
ConspectusOne of the constant challenges of synthetic chemistry is the molecular design and synthesis of nonionic, metal-free superbases as chemically stable neutral organic compounds of moderate molecular weight, intrinsically high thermodynamic basicity, adaptable kinetic basicity, and weak or tunable nucleophilicity at their nitrogen, phosphorus, or carbon basicity centers. Such superbases can catalyze numerous reactions, ranging from C-C bond formation to cycloadditions and polymerization, to name just a few. Additional benefits of organic superbases, as opposed to their inorganic counterparts, are their solubility in organic reaction media, mild reaction conditions, and higher selectivity. Approaching such superbasic compounds remains a continuous challenge. However, recent advances in synthetic methodology and theoretical understanding have resulted in new design principles and synthetic strategies toward superbases. Our computational contributions have demonstrated that the gas-phase basicity region of 350 kcal mol-1 and even beyond is easily reachable by organosuperbases. However, despite record-high basicities, the physical limitations of many of these compounds become quickly evident. The typically large molecular weight of these molecules and their sensitivity to ordinary reaction conditions prevent them from being practical, even though their preparation is often not too difficult. Thus, obviously structural limitations with respect to molecular weight and structural complexity must be imposed on the design of new synthetically useful organic superbases, but strategies for increasing their basicity remain important.The contemporary design of novel organic superbases is illustrated by phosphazenyl phosphanes displaying gas-phase basicities (GB) above 300 kcal mol-1 but having molecular weights well below 1000 g·mol-1. This approach is based on a reconsideration of phosphorus(III) compounds, which goes along with increasing their stability in solution. Another example is the preparation of carbodiphosphoranes incorporating pyrrolidine, tetramethylguanidine, or hexamethylphosphazene as a substituent. With gas-phase proton affinities of up to 300 kcal mol-1, they are among the top nonionic carbon bases on the basicity scale. Remarkably, the high basicity of these compounds is achieved at molecular weights of around 600 g·mol-1. Another approach to achieving high basicity through the cooperative effect of multiple intramolecular hydrogen bonding, which increases the stabilization of conjugate acids, has recently been confirmed.This Account focuses on our efforts to produce superbasic molecules that embody many desirable traits, but other groups' approaches will also be discussed. We reveal the crucial structural features of superbases and place them on known basicity scales. We discuss the emerging potential and current limits of their application and give a general outlook into the future.
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Affiliation(s)
- Katarina Vazdar
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, v.v.i. Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
| | | | | | - Jörg Sundermeyer
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße, 35032 Marburg, Germany
| | - Ivo Leito
- Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia
| | - Ullrich Jahn
- Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences, v.v.i. Flemingovo nám. 2, 166 10 Prague 6, Czech Republic
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41
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Weitkamp RF, Neumann B, Stammler H, Hoge B. Phosphorus-Containing Superbases: Recent Progress in the Chemistry of Electron-Abundant Phosphines and Phosphazenes. Chemistry 2021; 27:10807-10825. [PMID: 34032319 PMCID: PMC8362139 DOI: 10.1002/chem.202101065] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Indexed: 01/11/2023]
Abstract
The renaissance of Brønsted superbases is primarily based on their pronounced capacity for a large variety of chemical transformations under mild reaction conditions. Four major set screws are available for the selective tuning of the basicity: the nature of the basic center (N, P, …), the degree of electron donation by substituents to the central atom, the possibility of charge delocalization, and the energy gain by hydrogen bonding. Within the past decades, a plethora of neutral electron-rich phosphine and phosphazene bases have appeared in the literature. Their outstanding properties and advantages over inorganic or charged bases have now made them indispensable as auxiliary bases in deprotonation processes. Herein, an update of the chemistry of basic phosphines and phosphazenes is given. In addition, due to widespread interest, their use in catalysis or as ligands in coordination chemistry is highlighted.
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Affiliation(s)
- Robin F. Weitkamp
- Centrum für Molekulare MaterialienFakultät für ChemieUniversität BielefeldUniversitätsstraße 2533615BielefeldGermany
| | - Beate Neumann
- Centrum für Molekulare MaterialienFakultät für ChemieUniversität BielefeldUniversitätsstraße 2533615BielefeldGermany
| | - Hans‐Georg Stammler
- Centrum für Molekulare MaterialienFakultät für ChemieUniversität BielefeldUniversitätsstraße 2533615BielefeldGermany
| | - Berthold Hoge
- Centrum für Molekulare MaterialienFakultät für ChemieUniversität BielefeldUniversitätsstraße 2533615BielefeldGermany
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42
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Tang J, Yu X, Wang Y, Yamamoto Y, Bao M. Interweaving Visible‐Light and Iron Catalysis for Nitrene Formation and Transformation with Dioxazolones. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202016234] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Jing‐Jing Tang
- State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian 116023 China
| | - Xiaoqiang Yu
- State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian 116023 China
| | - Yi Wang
- State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian 116023 China
| | - Yoshinori Yamamoto
- State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian 116023 China
- WPI-Advanced Institute for Materials Research Tohoku University Sendai 980-8577 Japan
| | - Ming Bao
- State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian 116023 China
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43
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Tang JJ, Yu X, Wang Y, Yamamoto Y, Bao M. Interweaving Visible-Light and Iron Catalysis for Nitrene Formation and Transformation with Dioxazolones. Angew Chem Int Ed Engl 2021; 60:16426-16435. [PMID: 33843125 DOI: 10.1002/anie.202016234] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 02/02/2021] [Indexed: 02/02/2023]
Abstract
Herein, visible-light-driven iron-catalyzed nitrene transfer reactions with dioxazolones for intermolecular C(sp3 )-N, N=S, and N=P bond formation are described. These reactions occur with exogenous-ligand-free process and feature satisfactory to excellent yields (up to 99 %), an ample substrate scope (109 examples) under mild reaction conditions. In contrast to intramolecular C-H amidations strategies, an intermolecular regioselective C-H amidation via visible-light-induced nitrene transfer reactions is devised. Mechanistic studies indicate that the reaction proceeds via a radical pathway. Computational studies show that the decarboxylation of dioxazolone depends on the conversion of ground sextet state dioxazolone-bounding iron species to quartet spin state via visible-light irradiation.
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Affiliation(s)
- Jing-Jing Tang
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian, 116023, China
| | - Xiaoqiang Yu
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian, 116023, China
| | - Yi Wang
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian, 116023, China
| | - Yoshinori Yamamoto
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian, 116023, China.,WPI-Advanced Institute for Materials Research, Tohoku University, Sendai, 980-8577, Japan
| | - Ming Bao
- State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian, 116023, China
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44
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Guo F, Chen J, Huang Y. A Bifunctional N-Heterocyclic Carbene as a Noncovalent Organocatalyst for Enantioselective Aza-Michael Addition Reactions. ACS Catal 2021. [DOI: 10.1021/acscatal.1c01908] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Fangfang Guo
- State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen 518055, People’s Republic of China
| | - Jiean Chen
- Shenzhen Bay Laboratory, Shenzhen 518055, People’s Republic of China
| | - Yong Huang
- Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, People’s Republic of China
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45
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Umeno T, Usui K, Karasawa S. π‐Extended Push‐Pull‐Type Bicyclic Fluorophores Based on Quinoline and Naphthyridine Frameworks with an Iminophosphorane Fragment. ASIAN J ORG CHEM 2021. [DOI: 10.1002/ajoc.202100015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Tomohiro Umeno
- Faculty of Pharmaceutical Sciences Showa Pharmaceutical University 3-3165 Higashi-tamagawagakuen Machida 194-8543 Japan
| | - Kazuteru Usui
- Faculty of Pharmaceutical Sciences Showa Pharmaceutical University 3-3165 Higashi-tamagawagakuen Machida 194-8543 Japan
| | - Satoru Karasawa
- Faculty of Pharmaceutical Sciences Showa Pharmaceutical University 3-3165 Higashi-tamagawagakuen Machida 194-8543 Japan
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46
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Su G, Thomson CJ, Yamazaki K, Rozsar D, Christensen KE, Hamlin TA, Dixon DJ. A bifunctional iminophosphorane squaramide catalyzed enantioselective synthesis of hydroquinazolines via intramolecular aza-Michael reaction to α,β-unsaturated esters. Chem Sci 2021; 12:6064-6072. [PMID: 33996002 PMCID: PMC8098679 DOI: 10.1039/d1sc00856k] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
An efficient synthesis of enantioenriched hydroquinazoline cores via a novel bifunctional iminophosphorane squaramide catalyzed intramolecular aza-Michael reaction of urea-linked α,β-unsaturated esters is described. The methodology exhibits a high degree of functional group tolerance around the forming hydroquinazoline aryl core and wide structural variance on the nucleophilic N atom of the urea moiety. Excellent yields (up to 99%) and high enantioselectivities (up to 97 : 3 er) using both aromatic and less acidic aliphatic ureas were realized. The potential industrial applicability of the transformation was demonstrated in a 20 mmol scale-up experiment using an adjusted catalyst loading of 2 mol%. The origin of enantioselectivity and reactivity enhancement provided by the squaramide motif has been uncovered computationally using density functional theory (DFT) calculations, combined with the activation strain model (ASM) and energy decomposition analysis (EDA). The activation of both aromatic and aliphatic ureas as N-centered nucleophiles in intramolecular Michael addition reactions to α,β-unsaturated esters was achieved under bifunctional iminophosphorane squaramide superbase catalysis.![]()
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Affiliation(s)
- Guanglong Su
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford Mansfield Road Oxford OX1 3TA UK
| | - Connor J Thomson
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford Mansfield Road Oxford OX1 3TA UK
| | - Ken Yamazaki
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford Mansfield Road Oxford OX1 3TA UK .,Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam De Boelelaan 1083, 1081 HV Amsterdam The Netherlands
| | - Daniel Rozsar
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford Mansfield Road Oxford OX1 3TA UK
| | - Kirsten E Christensen
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford Mansfield Road Oxford OX1 3TA UK
| | - Trevor A Hamlin
- Department of Theoretical Chemistry, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Amsterdam Center for Multiscale Modeling (ACMM), Vrije Universiteit Amsterdam De Boelelaan 1083, 1081 HV Amsterdam The Netherlands
| | - Darren J Dixon
- Department of Chemistry, Chemistry Research Laboratory, University of Oxford Mansfield Road Oxford OX1 3TA UK
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47
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Orlandi M, Escudero-Casao M, Licini G. Nucleophilicity Prediction via Multivariate Linear Regression Analysis. J Org Chem 2021; 86:3555-3564. [PMID: 33534569 PMCID: PMC7901016 DOI: 10.1021/acs.joc.0c02952] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
![]()
The concept of nucleophilicity is
at the basis of most transformations
in chemistry. Understanding and predicting the relative reactivity
of different nucleophiles is therefore of paramount importance. Mayr’s
nucleophilicity scale likely represents the most complete collection
of reactivity data, which currently includes over 1200 nucleophiles.
Several attempts have been made to theoretically predict Mayr’s
nucleophilicity parameters N based on calculation
of molecular properties, but a general model accounting for different
classes of nucleophiles could not be obtained so far. We herein show
that multivariate linear regression analysis is a suitable tool for
obtaining a simple model predicting N for virtually
any class of nucleophiles in different solvents for a set of 341 data
points. The key descriptors of the model were found to account for
the proton affinity, solvation energies, and sterics.
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Affiliation(s)
- Manuel Orlandi
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy.,CIRCC-Consorzio Interuniversitario per le Reattività Chimiche e la Catalisi, Padova Unit, via Marzolo 1, 35131 Padova, Italy
| | - Margarita Escudero-Casao
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy.,CIRCC-Consorzio Interuniversitario per le Reattività Chimiche e la Catalisi, Padova Unit, via Marzolo 1, 35131 Padova, Italy
| | - Giulia Licini
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy.,CIRCC-Consorzio Interuniversitario per le Reattività Chimiche e la Catalisi, Padova Unit, via Marzolo 1, 35131 Padova, Italy
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48
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Lipshultz JM, Li G, Radosevich AT. Main Group Redox Catalysis of Organopnictogens: Vertical Periodic Trends and Emerging Opportunities in Group 15. J Am Chem Soc 2021; 143:1699-1721. [PMID: 33464903 PMCID: PMC7934640 DOI: 10.1021/jacs.0c12816] [Citation(s) in RCA: 117] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A growing number of organopnictogen redox catalytic methods have emerged-especially within the past 10 years-that leverage the plentiful reversible two-electron redox chemistry within Group 15. The goal of this Perspective is to provide readers the context to understand the dramatic developments in organopnictogen catalysis over the past decade with an eye toward future development. An exposition of the fundamental differences in the atomic structure and bonding of the pnictogens, and thus the molecular electronic structure of organopnictogen compounds, is presented to establish the backdrop against which organopnictogen redox reactivity-and ultimately catalysis-is framed. A deep appreciation of these underlying periodic principles informs an understanding of the differing modes of organopnictogen redox catalysis and evokes the key challenges to the field moving forward. We close by addressing forward-looking directions likely to animate this area in the years to come. What new catalytic manifolds can be developed through creative catalyst and reaction design that take advantage of the intrinsic redox reactivity of the pnictogens to drive new discoveries in catalysis?
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Affiliation(s)
- Jeffrey M Lipshultz
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Gen Li
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Alexander T Radosevich
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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49
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Maegawa K, Tanimoto H, Onishi S, Tomohiro T, Morimoto T, Kakiuchi K. Taming the reactivity of alkyl azides by intramolecular hydrogen bonding: site-selective conjugation of unhindered diazides. Org Chem Front 2021. [DOI: 10.1039/d1qo01088c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The intramolecular hydrogen bonding in the α-azido secondary acetamides (α-AzSAs) enabled site-selective integration onto the diazide modular hubs even without steric hindrance.
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Affiliation(s)
- Koshiro Maegawa
- Division of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayamacho, Ikoma, Nara 630-0192, Japan
| | - Hiroki Tanimoto
- Division of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayamacho, Ikoma, Nara 630-0192, Japan
- Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Seiji Onishi
- Division of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayamacho, Ikoma, Nara 630-0192, Japan
| | - Takenori Tomohiro
- Faculty of Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
| | - Tsumoru Morimoto
- Division of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayamacho, Ikoma, Nara 630-0192, Japan
| | - Kiyomi Kakiuchi
- Division of Materials Science, Nara Institute of Science and Technology (NAIST), 8916-5 Takayamacho, Ikoma, Nara 630-0192, Japan
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