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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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2
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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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3
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Bio-Based Polymer Developments from Tall Oil Fatty Acids by Exploiting Michael Addition. Polymers (Basel) 2022; 14:polym14194068. [PMID: 36236017 PMCID: PMC9571392 DOI: 10.3390/polym14194068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/23/2022] [Accepted: 09/24/2022] [Indexed: 01/14/2023] Open
Abstract
In this study, previously developed acetoacetates of two tall-oil-based and two commercial polyols were used to obtain polymers by the Michael reaction. The development of polymer formulations with varying cross-link density was enabled by different bio-based monomers in combination with different acrylates—bisphenol A ethoxylate diacrylate, trimethylolpropane triacrylate, and pentaerythritol tetraacrylate. New polymer materials are based on the same polyols that are suitable for polyurethanes. The new polymers have qualities comparable to polyurethanes and are obtained without the drawbacks that come with polyurethane extractions, such as the use of hazardous isocyanates or reactions under harsh conditions in the case of non-isocyanate polyurethanes. Dynamic mechanical analysis, differential scanning calorimetry, thermal gravimetric analysis, and universal strength testing equipment were used to investigate the physical and thermal characteristics of the created polymers. Polymers with a wide range of thermal and mechanical properties were obtained (glass transition temperature from 21 to 63 °C; tensile modulus (Young’s) from 8 MPa to 2710 MPa and tensile strength from 4 to 52 MPa). The synthesized polymers are thermally stable up to 300 °C. The suggested method may be used to make two-component polymer foams, coatings, resins, and composite matrices.
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4
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Abstract
Synthetic chemists have long focused on selective C(sp 3)-N bond-forming approaches in response to the high value of this motif in natural products, pharmaceutical agents and functional materials. In recent years, visible light-induced protocols have become an important synthetic platform to promote this transformation under mild reaction conditions. These photo-driven methods rely on converting visible light into chemical energy to generate reactive but controllable radical species. This Review highlights recent advances in this area, mostly after 2014, with an emphasis placed on C(sp 3)-H bond activations, including amination of olefins and carbonyl compounds, and cross-coupling reactions.
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5
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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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6
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Jiang Q, Qin T, Yang X. Asymmetric Synthesis of Hydroquinazolines Bearing C4-Tetrasubstituted Stereocenters via Kinetic Resolution of α-Tertiary Amines. Org Lett 2022; 24:625-630. [PMID: 34978827 DOI: 10.1021/acs.orglett.1c04039] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
A novel protocol for asymmetric synthesis of hydroquinazolines bearing C4-tetrasubstituted stereocenters has been achieved through kinetic resolution of 2-amido α-tertiary benzylamines via chiral phosphoric acid catalyzed intramolecular dehydrative cyclizations. This method gave access to both α-tertiary benzylamines and hydroquinazolines with broad scope and high enantioselectivities. An intriguing restricted rotation of the C-N bond was observed for hydroquinazoline products bearing C4-tetrasubstituted stereocenters.
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Affiliation(s)
- Qianwen Jiang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Tianren Qin
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xiaoyu Yang
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
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7
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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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Chan YC, Sak MH, Frank SA, Miller SJ. Tunable and Cooperative Catalysis for Enantioselective Pictet-Spengler Reaction with Varied Nitrogen-Containing Heterocyclic Carboxaldehydes. Angew Chem Int Ed Engl 2021; 60:24573-24581. [PMID: 34487418 PMCID: PMC8556314 DOI: 10.1002/anie.202109694] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 08/24/2021] [Indexed: 01/16/2023]
Abstract
Herein we report an organocatalytic enantioselective functionalization of heterocyclic carboxaldehydes via the Pictet-Spengler reaction. Through careful pairing of novel squaramide and Brønsted acid catalysts, our method tolerates a breadth of heterocycles, enabling preparation of a series of heterocycle conjugated β-(tetrahydro)carbolines in good yield and enantioselectivity. Careful selection of carboxylic acid co-catalyst is essential for toleration of a variety of regioisomeric heterocycles. Utility is demonstrated via the three-step stereoselective preparation of pyridine-containing analogues of potent selective estrogen receptor downregulator and U.S. FDA approved drug Tadalafil.
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Affiliation(s)
- Yuk-Cheung Chan
- Department of Chemistry, Yale University, New Haven, CT, 06520, USA
| | - Marcus H Sak
- Department of Chemistry, Yale University, New Haven, CT, 06520, USA
| | - Scott A Frank
- Synthetic Molecule Design and Development, Eli Lilly and Company, Indianapolis, IN, 46285, USA
| | - Scott J Miller
- Department of Chemistry, Yale University, New Haven, CT, 06520, USA
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9
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Chan Y, Sak MH, Frank SA, Miller SJ. Tunable and Cooperative Catalysis for Enantioselective Pictet‐Spengler Reaction with Varied Nitrogen‐Containing Heterocyclic Carboxaldehydes. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202109694] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Yuk‐Cheung Chan
- Department of Chemistry Yale University New Haven CT 06520 USA
| | - Marcus H. Sak
- Department of Chemistry Yale University New Haven CT 06520 USA
| | - Scott A. Frank
- Synthetic Molecule Design and Development Eli Lilly and Company Indianapolis IN 46285 USA
| | - Scott J. Miller
- Department of Chemistry Yale University New Haven CT 06520 USA
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10
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Sánchez-Roselló M, Escolano M, Gaviña D, Del Pozo C. Two Decades of Progress in the Asymmetric Intramolecular aza-Michael Reaction. CHEM REC 2021; 22:e202100161. [PMID: 34415097 DOI: 10.1002/tcr.202100161] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 07/22/2021] [Accepted: 08/04/2021] [Indexed: 11/08/2022]
Abstract
The asymmetric intramolecular aza-Michael reaction (IMAMR) is a very convenient strategy for the generation of heterocycles bearing nitrogen-substituted stereocenters. Due to the ubiquitous presence of these skeletons in natural products, the IMAMR has found widespread applications in the total synthesis of alkaloids and biologically relevant compounds. The development of asymmetric versions of the IMAMR are quite recent, most of them reported in this century. The fundamental advances in this field involve the use of organocatalysts. Chiral imidazolidinones, diaryl prolinol derivatives, Cinchone-derived primary amines and quaternary ammonium salts, and BINOL-derived phosphoric acids account for the success of those methodologies. Moreover, the use of N-sulfinyl imines with a dual role, as nitrogen nucleophiles and as chiral auxiliaries, appeared as a versatile mode of performing the asymmetric IMAMR.
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Affiliation(s)
- María Sánchez-Roselló
- Organic Chemistry, University of Valencia, Avda Vicente Andrés Estellés s/n, 46100-Burjassot, Valencia), Spain
| | - Marcos Escolano
- Organic Chemistry, University of Valencia, Avda Vicente Andrés Estellés s/n, 46100-Burjassot, Valencia), Spain
| | - Daniel Gaviña
- Organic Chemistry, University of Valencia, Avda Vicente Andrés Estellés s/n, 46100-Burjassot, Valencia), Spain
| | - Carlos Del Pozo
- Organic Chemistry, University of Valencia, Avda Vicente Andrés Estellés s/n, 46100-Burjassot, Valencia), Spain
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