1
|
Piringer M, Hofer M, Vogl LS, Mayer P, Waser M. Enantioselective Syntheses of 3,4-Dihydropyrans Employing Isochalcogenourea-Catalyzed Formal (4+2)-Cycloadditions of Allenoates. Adv Synth Catal 2024; 366:2115-2122. [PMID: 38840716 PMCID: PMC7616061 DOI: 10.1002/adsc.202400038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Indexed: 06/07/2024]
Abstract
We herein successfully demonstrate the use of chiral isochalcogenoureas as Lewis Base catalysts for a variety of (4+2)-cycloaddition reactions of allenoates and different Michael acceptors. In all cases the same structural key-motive, a dihydropyran with a (Z)-configurated exocyclic double bond could be accessed as the major regio- and diastereoisomer in an enantioselective manner. Furthermore, these chiral dihydropyrans were successfully engaged in different follow-up transformations.
Collapse
Affiliation(s)
- Magdalena Piringer
- Institute of Organic Chemistry, Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria + 43 732 2468 5411
| | - Mario Hofer
- Institute of Organic Chemistry, Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria + 43 732 2468 5411
| | - Lukas S. Vogl
- Institute of Organic Chemistry, Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria + 43 732 2468 5411
| | - Peter Mayer
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstraße 5–13, 81377 München, Germany
| | - Mario Waser
- Institute of Organic Chemistry, Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria + 43 732 2468 5411
| |
Collapse
|
2
|
Vogl LS, Mayer P, Robiette R, Waser M. Chiral Isochalcogenourea-Catalysed Enantioselective (4+2) Cycloadditions of Allenoates. Angew Chem Int Ed Engl 2024; 63:e202315345. [PMID: 38010747 PMCID: PMC10952905 DOI: 10.1002/anie.202315345] [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: 10/11/2023] [Revised: 11/13/2023] [Accepted: 11/27/2023] [Indexed: 11/29/2023]
Abstract
Allenoates are versatile building blocks which are primarily activated and controlled using chiral tert. phosphine and tert. amine Lewis bases. We herein report the first example of allenoate activation by using chiral isochalcogenoureas (IChU) for formal (4+2) cycloaddition reactions. Compared to established phosphine and amine catalysis, the use of these easily available Lewis bases enables new stereoselective reaction pathways proceeding with high enantioselectivities, diastereoselectivities, and in good yields. In addition, the factors governing enantioselectivity and the origin of the observed differences compared to other commonly used Lewis bases are explained.
Collapse
Affiliation(s)
- Lukas S. Vogl
- Institute of Organic ChemistryJohannes Kepler University LinzAltenbergerstrasse 694040LinzAustria
| | - Peter Mayer
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstraße 5–1381377MünchenGermany
| | - Raphaël Robiette
- Institute of Condensed Matter and NanosciencesUniversité catholique de LouvainPlace Louis Pasteur 1 box L4.01.021348Louvain-la-NeuveBelgium
| | - Mario Waser
- Institute of Organic ChemistryJohannes Kepler University LinzAltenbergerstrasse 694040LinzAustria
| |
Collapse
|
3
|
Vogl LS, Mayer P, Robiette R, Waser M. Chiral Isochalcogenourea-Catalysed Enantioselective (4+2) Cycloadditions of Allenoates. ANGEWANDTE CHEMIE (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 136:e202315345. [PMID: 38549953 PMCID: PMC10976662 DOI: 10.1002/ange.202315345] [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: 10/11/2023] [Indexed: 06/02/2024]
Abstract
Allenoates are versatile building blocks which are primarily activated and controlled using chiral tert. phosphine and tert. amine Lewis bases. We herein report the first example of allenoate activation by using chiral isochalcogenoureas (IChU) for formal (4+2) cycloaddition reactions. Compared to established phosphine and amine catalysis, the use of these easily available Lewis bases enables new stereoselective reaction pathways proceeding with high enantioselectivities, diastereoselectivities, and in good yields. In addition, the factors governing enantioselectivity and the origin of the observed differences compared to other commonly used Lewis bases are explained.
Collapse
Affiliation(s)
- Lukas S. Vogl
- Institute of Organic ChemistryJohannes Kepler University LinzAltenbergerstrasse 694040LinzAustria
| | - Peter Mayer
- Department ChemieLudwig-Maximilians-Universität MünchenButenandtstraße 5–1381377MünchenGermany
| | - Raphaël Robiette
- Institute of Condensed Matter and NanosciencesUniversité catholique de LouvainPlace Louis Pasteur 1 box L4.01.021348Louvain-la-NeuveBelgium
| | - Mario Waser
- Institute of Organic ChemistryJohannes Kepler University LinzAltenbergerstrasse 694040LinzAustria
| |
Collapse
|
4
|
Gong Z, Smith A, Farah AO, Dickerson SD, González-Montiel GA, Laddusaw JM, Cheong PHY, Wiskur SL. Investigating Substituent Interactions with Cationic Catalysts. J Org Chem 2023. [PMID: 37993265 DOI: 10.1021/acs.joc.3c01721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2023]
Abstract
Rates of isothiourea catalyzed silylation and acylation reactions were measured for substrates with various electronic substituents at the aryl group. Through these measurements, the intermolecular interactions between cationic catalyst intermediates and different aryl groups were explored. These studies were performed to understand how changes in the catalyst structure affected electrostatic intermolecular interactions. Three different catalysts (N-methylimidazole and two isothioureas) were employed that varied in their ability to delocalize their cationic nature. The results show that more delocalization on the catalyst reduces the sensitivity to the electronics on the aryl group. Surprisingly, the isothiourea with a fused benzene ring provided additional points of interaction with groups that contained lone-pairs, significantly affecting the overall rate. This work helps explore the interactions that dominate in these types of catalytic systems, to aid in future organocatalysis development. Density functional theory (DFT) studies further confirmed isothiourea/aryl ring interaction with the alcohol substrate in the acylation process, which confirmed these hypotheses. Electron rich or lone-pair bearing functional groups stabilize the cationic catalyst core, thereby stabilizing the transition states and accelerating the reaction. It was also discovered that in one case, the formation of a stable substrate dimer was responsible for its lower reactivity.
Collapse
Affiliation(s)
- Ziyuan Gong
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter Street, GSRC 109, Columbia, South Carolina 29206, United States
| | - Alberto Smith
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter Street, GSRC 109, Columbia, South Carolina 29206, United States
| | - Abdikani Omar Farah
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, United States
| | - Shelby D Dickerson
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter Street, GSRC 109, Columbia, South Carolina 29206, United States
| | - Gisela A González-Montiel
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, United States
| | - Jacqueline M Laddusaw
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, United States
| | - Paul Ha-Yeon Cheong
- Department of Chemistry, Oregon State University, 153 Gilbert Hall, Corvallis, Oregon 97331, United States
| | - Sheryl L Wiskur
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter Street, GSRC 109, Columbia, South Carolina 29206, United States
| |
Collapse
|
5
|
Stockhammer L, Radetzky M, Khatoon SS, Bechmann M, Waser M. Chiral Lewis Base-Catalysed Asymmetric Syntheses of Benzo-fused ϵ-Lactones. European J Org Chem 2023; 26:e202300704. [PMID: 38601860 PMCID: PMC11005097 DOI: 10.1002/ejoc.202300704] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 08/24/2023] [Indexed: 04/12/2024]
Abstract
We herein report a two-step protocol for the asymmetric synthesis of novel chiral benzofused ϵ-lactones starting from O-protected hydroxymethyl-para-quinone methides and activated aryl esters. By using chiral isothiourea Lewis base catalysts a broad variety of differently substituted products could be obtained in yields of around 50 % over both steps with high levels of enantioselectivities, albeit low diastereoselectivities only.
Collapse
Affiliation(s)
- Lotte Stockhammer
- Institute of Organic ChemistryJohannes Kepler University LinzAltenbergerstrasse 694040LinzAustria
| | - Maximilian Radetzky
- Institute of Organic ChemistryJohannes Kepler University LinzAltenbergerstrasse 694040LinzAustria
| | - Syeda Sadia Khatoon
- Institute of Organic ChemistryJohannes Kepler University LinzAltenbergerstrasse 694040LinzAustria
| | - Matthias Bechmann
- Institute of Organic ChemistryJohannes Kepler University LinzAltenbergerstrasse 694040LinzAustria
| | - Mario Waser
- Institute of Organic ChemistryJohannes Kepler University LinzAltenbergerstrasse 694040LinzAustria
| |
Collapse
|
6
|
Dale HA, Hodges GR, Lloyd-Jones GC. Kinetics and Mechanism of Azole n-π*-Catalyzed Amine Acylation. J Am Chem Soc 2023; 145:18126-18140. [PMID: 37526380 PMCID: PMC10436283 DOI: 10.1021/jacs.3c06258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Indexed: 08/02/2023]
Abstract
Azole anions are highly competent in the activation of weak acyl donors, but, unlike neutral (aprotic) Lewis bases, are not yet widely applied as acylation catalysts. Using a combination of in situ and stopped-flow 1H/19F NMR spectroscopy, kinetics, isotopic labeling, 1H DOSY, and electronic structure calculations, we have investigated azole-catalyzed aminolysis of p-fluorophenyl acetate. The global kinetics have been elucidated under four sets of conditions, and the key elementary steps underpinning catalysis deconvoluted using a range of intermediates and transition state probes. While all evidence points to an overarching mechanism involving n-π* catalysis via N-acylated azole intermediates, a diverse array of kinetic regimes emerges from this framework. Even seemingly minor changes to the solvent, auxiliary base, or azole catalyst can elicit profound changes in the temporal evolution, thermal sensitivity, and progressive inhibition of catalysis. These observations can only be rationalized by taking a holistic view of the mechanism and a set of limiting regimes for the kinetics. Overall, the analysis of 18 azole catalysts spanning nearly 10 orders of magnitude in acidity highlights the pitfall of pursuing ever more nucleophilic catalysts without regard for catalyst speciation.
Collapse
Affiliation(s)
- Harvey
J. A. Dale
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K.
| | - George R. Hodges
- Jealott’s
Hill International Research Centre, Syngenta, Bracknell, Berkshire RG42 6EY, U.K.
| | - Guy C. Lloyd-Jones
- EaStChem, University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ, U.K.
| |
Collapse
|
7
|
Weinzierl D, Piringer M, Zebrowski P, Stockhammer L, Waser M. Photochemical Wolff Rearrangement Initiated Generation and Subsequent α-Chlorination of C1 Ammonium Enolates. Org Lett 2023; 25:3126-3130. [PMID: 37098273 PMCID: PMC10167681 DOI: 10.1021/acs.orglett.3c00986] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Indexed: 04/27/2023]
Abstract
The enantioselective synthesis of α-chlorinated carboxylic acid esters with er up to 99:1 and yields up to 82% was achieved via a one-pot multistep protocol starting from α-diazoketones. This process proceeds via a photochemical Wolff rearrangement, trapping of the generated ketene with a chiral Lewis base catalyst, subsequent enantioselective α-chlorination, and a final nucleophilic displacement of the bound catalyst. The obtained products were successfully utilized for stereospecific nucleophilic displacement reactions with N- and S-nucleophiles.
Collapse
Affiliation(s)
- David Weinzierl
- Institute
of Organic Chemistry, Johannes Kepler University
Linz, Altenbergerstr. 69, 4040 Linz, Austria
| | - Magdalena Piringer
- Institute
of Organic Chemistry, Johannes Kepler University
Linz, Altenbergerstr. 69, 4040 Linz, Austria
| | - Paul Zebrowski
- Institute
of Organic Chemistry, Johannes Kepler University
Linz, Altenbergerstr. 69, 4040 Linz, Austria
| | - Lotte Stockhammer
- Institute
of Organic Chemistry, Johannes Kepler University
Linz, Altenbergerstr. 69, 4040 Linz, Austria
| | - Mario Waser
- Institute
of Organic Chemistry, Johannes Kepler University
Linz, Altenbergerstr. 69, 4040 Linz, Austria
| |
Collapse
|
8
|
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] [Grants] [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.
Collapse
Affiliation(s)
- Simone Gallarati
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Puck van Gerwen
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
- National Center for Competence in Research - Catalysis (NCCR-Catalysis), Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Ruben Laplaza
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
- National Center for Competence in Research - Catalysis (NCCR-Catalysis), Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Sergi Vela
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Alberto Fabrizio
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
- National Center for Computational Design and Discovery of Novel Materials (MARVEL), Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| | - Clemence Corminboeuf
- Laboratory for Computational Molecular Design, Institute of Chemical Sciences and Engineering, Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
- National Center for Competence in Research - Catalysis (NCCR-Catalysis), Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
- National Center for Computational Design and Discovery of Novel Materials (MARVEL), Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland
| |
Collapse
|
9
|
Taylor NP, Gonzalez JA, Nichol GS, García-Domínguez A, Leach AG, Lloyd-Jones GC. A Lewis Base Nucleofugality Parameter, NFB, and Its Application in an Analysis of MIDA-Boronate Hydrolysis Kinetics. J Org Chem 2021; 87:721-729. [PMID: 34928611 DOI: 10.1021/acs.joc.1c02729] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The kinetics of quinuclidine displacement of BH3 from a wide range of Lewis base borane adducts have been measured. Parameterization of these rates has enabled the development of a nucleofugality scale (NFB), shown to quantify and predict the leaving group ability of a range of other Lewis bases. Additivity observed across a number of series R'3-nRnX (X = P, N; R' = aryl, alkyl) has allowed the formulation of related substituent parameters (nfPB, nfAB), providing a means of calculating NFB values for a range of Lewis bases that extends far beyond those experimentally derived. The utility of the nucleofugality parameter is explored by the correlation of the substituent parameter nfPB with the hydrolyses rates of a series of alkyl and aryl MIDA boronates under neutral conditions. This has allowed the identification of MIDA boronates with heteroatoms proximal to the reacting center, showing unusual kinetic lability or stability to hydrolysis.
Collapse
Affiliation(s)
- Nicholas P Taylor
- EaStChem, School of Chemistry, University of Edinburgh, Joseph Black Building, Edinburgh EH9 3FJ, United Kingdom
| | - Jorge A Gonzalez
- EaStChem, School of Chemistry, University of Edinburgh, Joseph Black Building, Edinburgh EH9 3FJ, United Kingdom
| | - Gary S Nichol
- EaStChem, School of Chemistry, University of Edinburgh, Joseph Black Building, Edinburgh EH9 3FJ, United Kingdom
| | - Andrés García-Domínguez
- EaStChem, School of Chemistry, University of Edinburgh, Joseph Black Building, Edinburgh EH9 3FJ, United Kingdom
| | - Andrew G Leach
- School of Health Sciences, Stopford Building, The University of Manchester, Oxford Road, Manchester M13 9PT, United Kingdom
| | - Guy C Lloyd-Jones
- EaStChem, School of Chemistry, University of Edinburgh, Joseph Black Building, Edinburgh EH9 3FJ, United Kingdom
| |
Collapse
|
10
|
Redden BK, Clark RW, Gong Z, Rahman MM, Peryshkov DV, Wiskur SL. Mechanistic investigations of alcohol silylation with isothiourea catalysts. Org Biomol Chem 2021; 19:10181-10188. [PMID: 34787145 DOI: 10.1039/d1ob01732b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The mechanism of the asymmetric silylation of alcohols with isothiourea catalysts was studied by employing reaction progress kinetic analysis. These reactions were developed by the Wiskur group, and use triphenyl silyl chloride and chiral isothiourea catalysts to silylate the alcohols. While the order of most reaction components was as expected (catalyst, amine base, alcohol), the silyl chloride was determined to be a higher order. This suggested a multistep mechanism between the catalyst and silyl chloride, with the second equivalent of silyl chloride assisting in the formation of the reactive intermediate leading to the rate-determining step. Through the addition of additives and investigating changes in the silyl chloride, an understanding of the catalyst equilibrium emerged for this reaction and provided pathways for further reaction development.
Collapse
Affiliation(s)
- Brandon K Redden
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter St., Columbia, SC 29208, USA.
| | - Robert W Clark
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter St., Columbia, SC 29208, USA.
| | - Ziyuan Gong
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter St., Columbia, SC 29208, USA.
| | - Md Mamdudur Rahman
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter St., Columbia, SC 29208, USA.
| | - Dmitry V Peryshkov
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter St., Columbia, SC 29208, USA.
| | - Sheryl L Wiskur
- Department of Chemistry and Biochemistry, University of South Carolina, 631 Sumter St., Columbia, SC 29208, USA.
| |
Collapse
|
11
|
Stockhammer L, Weinzierl D, Bögl T, Waser M. Enantioselective α-Chlorination Reactions of in Situ Generated C1 Ammonium Enolates under Base-Free Conditions. Org Lett 2021; 23:6143-6147. [PMID: 34319102 PMCID: PMC8353620 DOI: 10.1021/acs.orglett.1c02256] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
![]()
The asymmetric α-chlorination
of activated aryl acetic acid
esters can be carried out with high levels of enantioselectivities
utilizing commercially available isothiourea catalysts under base-free
conditions. The reaction, which proceeds via the in situ formation
of chiral C1 ammonium enolates, is best carried out under cryogenic
conditions combined with a direct trapping of the activated α-chlorinated
ester derivative to prevent epimerization, thus allowing for enantioselectivities
of up to e.r. 99:1.
Collapse
Affiliation(s)
- Lotte Stockhammer
- Institute of Organic Chemistry, Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria
| | - David Weinzierl
- Institute of Organic Chemistry, Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria
| | - Thomas Bögl
- Institute of Analytical Chemistry, Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria
| | - Mario Waser
- Institute of Organic Chemistry, Johannes Kepler University Linz, Altenbergerstr. 69, 4040 Linz, Austria
| |
Collapse
|
12
|
Kinens A, Balkaitis S, Ahmad OK, Piotrowski DW, Suna E. Acylative Dynamic Kinetic Resolution of Secondary Alcohols: Tandem Catalysis by HyperBTM and Bäckvall's Ruthenium Complex. J Org Chem 2021; 86:7189-7202. [PMID: 33974415 DOI: 10.1021/acs.joc.1c00545] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Non-enzymatic dynamic kinetic resolution (DKR) of secondary alcohols by enantioselective acylation using an isothiourea-derived HyperBTM catalyst and racemization of slowly reacting alcohol by Bäckvall's ruthenium complex is reported. The DKR approach features high enantioselectivities (up to 99:1), employs easy-to-handle crystalline 4-nitrophenyl isobutyrate as the acylating reagent, and proceeds at room temperature and under an ambient atmosphere. The stereoinduction model featuring cation-π system interactions between the acylated HyperBTM catalyst and π electrons of an alcohol aryl subunit has been elaborated by DFT calculations.
Collapse
Affiliation(s)
- Artis Kinens
- Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga LV-1006, Latvia.,Department of Chemistry, University of Latvia, Jelgavas 1, Riga LV-1004, Latvia
| | - Simonas Balkaitis
- Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga LV-1006, Latvia.,Department of Chemistry, University of Latvia, Jelgavas 1, Riga LV-1004, Latvia
| | - Omar K Ahmad
- Worldwide Medicinal Chemistry, Pfizer, Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - David W Piotrowski
- Worldwide Medicinal Chemistry, Pfizer, Inc., Eastern Point Road, Groton, Connecticut 06340, United States
| | - Edgars Suna
- Latvian Institute of Organic Synthesis, Aizkraukles 21, Riga LV-1006, Latvia.,Department of Chemistry, University of Latvia, Jelgavas 1, Riga LV-1004, Latvia
| |
Collapse
|
13
|
Biswas A, Mondal H, Maji MS. Synthesis of Heterocycles by isothiourea organocatalysis. J Heterocycl Chem 2020. [DOI: 10.1002/jhet.4119] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Anup Biswas
- Department of Chemistry Hooghly Women's College Hooghly India
| | - Haripriyo Mondal
- Department of Chemistry Indian Institute of Technology Kharagpur India
| | - Modhu S. Maji
- Department of Chemistry Indian Institute of Technology Kharagpur India
| |
Collapse
|
14
|
Jarrige L, Glavač D, Levitre G, Retailleau P, Bernadat G, Neuville L, Masson G. Chiral phosphoric acid-catalyzed enantioselective construction of structurally diverse benzothiazolopyrimidines. Chem Sci 2019; 10:3765-3769. [PMID: 31015920 PMCID: PMC6461124 DOI: 10.1039/c8sc05581e] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Accepted: 02/06/2019] [Indexed: 11/24/2022] Open
Abstract
A highly efficient catalytic enantioselective [4+2] cycloaddition was developed between 2-benzothiazolimines and enecarbamates. A wide range of benzothiazolopyrimidines bearing three contiguous stereogenic centers was obtained in high to excellent yields and with excellent diastereo- and enantioselectivities (d.r. > 98 : 2 and up to >99% ee). Furthermore, this chiral phosphoric acid-catalyzed strategy was scalable and enabled access to a new class of optically pure Lewis base isothiourea derivatives.
Collapse
Affiliation(s)
- Lucie Jarrige
- Institut de Chimie des Substances Naturelles , CNRS UPR 2301 , Université Paris-Sud , Université Paris-Saclay , 1, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex , France .
| | - Danijel Glavač
- Institut de Chimie des Substances Naturelles , CNRS UPR 2301 , Université Paris-Sud , Université Paris-Saclay , 1, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex , France .
- Ruđer Bošković Institute , Division of Organic Chemistry and Biochemistry , Bijenička cesta 54 , 10000 Zagreb , Croatia
| | - Guillaume Levitre
- Institut de Chimie des Substances Naturelles , CNRS UPR 2301 , Université Paris-Sud , Université Paris-Saclay , 1, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex , France .
| | - Pascal Retailleau
- Institut de Chimie des Substances Naturelles , CNRS UPR 2301 , Université Paris-Sud , Université Paris-Saclay , 1, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex , France .
| | - Guillaume Bernadat
- Laboratoire Chimie Thérapeutique , Faculté de Pharmacie Biocis 8076 , LabEx LERMIT , 5, rue J. B. Clément, 92296 Châtenay Malabry , France
| | - Luc Neuville
- Institut de Chimie des Substances Naturelles , CNRS UPR 2301 , Université Paris-Sud , Université Paris-Saclay , 1, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex , France .
| | - Géraldine Masson
- Institut de Chimie des Substances Naturelles , CNRS UPR 2301 , Université Paris-Sud , Université Paris-Saclay , 1, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex , France .
| |
Collapse
|
15
|
Neyyappadath RM, Chisholm R, Greenhalgh MD, Rodríguez-Escrich C, Pericàs MA, Hähner G, Smith AD. Acylative Kinetic Resolution of Alcohols Using a Recyclable Polymer-Supported Isothiourea Catalyst in Batch and Flow. ACS Catal 2018. [DOI: 10.1021/acscatal.7b04001] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
| | - Ross Chisholm
- EaStCHEM,
School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST, U.K
| | - Mark D. Greenhalgh
- EaStCHEM,
School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST, U.K
| | - Carles Rodríguez-Escrich
- Institute
of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007 Tarragona, Spain
| | - Miquel A. Pericàs
- Institute
of Chemical Research of Catalonia (ICIQ), The Barcelona Institute of Science and Technology, Av. Països Catalans 16, 43007 Tarragona, Spain
- Department
de Química Inorgànica i Orgànica, Universitat de Barcelona, 08080 Barcelona, Spain
| | - Georg Hähner
- EaStCHEM,
School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST, U.K
| | - Andrew D. Smith
- EaStCHEM,
School of Chemistry, University of St Andrews, North Haugh, St Andrews KY16 9ST, U.K
| |
Collapse
|
16
|
Bai J, Wang J, Wang Y, Zhang L. Dual catalysis system for ring-opening polymerization of lactones and 2,2-dimethyltrimethylene carbonate. Polym Chem 2018. [DOI: 10.1039/c8py01230j] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The dual catalysis system exhibit the characteristics of a controlled ROP and suitable activities for the ROP of lactones and carbonates. Polymers prepared through this dual catalytic route possess predictable molecular weights, narrow polydispersities, and high end-group fidelity.
Collapse
Affiliation(s)
- Junhua Bai
- School of Chemistry & Material Science
- Shanxi Normal University
- Linfen 041004
- P. R. China
| | - Jinhua Wang
- School of Chemistry & Material Science
- Shanxi Normal University
- Linfen 041004
- P. R. China
| | - Yan Wang
- School of Chemistry & Material Science
- Shanxi Normal University
- Linfen 041004
- P. R. China
| | - Lifang Zhang
- School of Chemistry & Material Science
- Shanxi Normal University
- Linfen 041004
- P. R. China
- Research Institute of Materials Science of Shanxi Normal University & Collaborative Innovation Center for Shanxi Advanced Permanent Magnetic Materials and Techonology
| |
Collapse
|
17
|
Ahlemeyer NA, Streff EV, Muthupandi P, Birman VB. Dramatic Acceleration of an Acyl Transfer-Initiated Cascade by Using Electron-Rich Amidine-Based Catalysts. Org Lett 2017; 19:6486-6489. [PMID: 29200308 DOI: 10.1021/acs.orglett.7b03044] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A tandem rearrangement of α,β-unsaturated thioesters into tricyclic ene-lactones fails with conventional amidine-based catalysts, but becomes possible when their electron-rich analogs are employed. A highly diastereo- and enantioselective version of this process has been developed using H-PIP 1b, a chiral catalyst prepared over a decade ago, but never utilized since its disclosure.
Collapse
Affiliation(s)
- Nicholas A Ahlemeyer
- Washington University Department of Chemistry , Campus Box 1134, One Brookings Drive, Saint Louis, Missouri 63130, United States
| | - Emma V Streff
- Washington University Department of Chemistry , Campus Box 1134, One Brookings Drive, Saint Louis, Missouri 63130, United States
| | - Pandi Muthupandi
- Washington University Department of Chemistry , Campus Box 1134, One Brookings Drive, Saint Louis, Missouri 63130, United States
| | - Vladimir B Birman
- Washington University Department of Chemistry , Campus Box 1134, One Brookings Drive, Saint Louis, Missouri 63130, United States
| |
Collapse
|
18
|
Mayr H, Ofial AR. Philicity, fugality, and equilibrium constants: when do rate-equilibrium relationships break down? PURE APPL CHEM 2017. [DOI: 10.1515/pac-2017-0107] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractLinear free energy relationships, in particular relationships between rate and equilibrium constants, are the basis for our rationalization of organic reactivity. Whereas relationships between the kinetic terms nucleophilicity and nucleofugality and the thermodynamic term basicity have been in the focus of interest for many decades, much less attention has been paid to the relationships between electrophilicity, electrofugality, and Lewis acidity. By using p- and m-substituted benzhydrylium ions (Aryl2CH+) as reference electrophiles, reference electrofuges, and reference Lewis acids of widely varying electron demand and constant steric surroundings of the reaction center, we have developed comprehensive reactivity scales which can be employed for classifying polar organic reactivity and for rationally designing synthetic transformations. It is a general rule that structural variations in electron-surplus species, which increase basicities, also increase nucleophilicities and decrease nucleofugalities, and that structural variations in electron-deficient species, which increase Lewis acidities also increase electrophilicities and decrease electrofugalities. Deviations from this behavior are analyzed, and it is shown that variations in intrinsic barriers are responsible for the counterintuitive observations that structural variation in one of the reactants alters the rates of forward and backward reactions in the same direction. A spectacular example of this phenomenon is found in vinyl cation chemistry: Vinyl cations are not only generated several orders of magnitude more slowly in SN1 reactions than benzhydrylium ions of the same Lewis acidity, but also react much more slowly with nucleophiles.
Collapse
Affiliation(s)
- Herbert Mayr
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München, Germany
| | - Armin R. Ofial
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München, Germany
| |
Collapse
|
19
|
Merad J, Pons JM, Chuzel O, Bressy C. Enantioselective Catalysis by Chiral Isothioureas. European J Org Chem 2016. [DOI: 10.1002/ejoc.201600399] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Jérémy Merad
- Aix Marseille Université, Centrale Marseille; CNRS, iSm2 UMR 7313; 13397 Marseille France
| | - Jean-Marc Pons
- Aix Marseille Université, Centrale Marseille; CNRS, iSm2 UMR 7313; 13397 Marseille France
| | - Olivier Chuzel
- Aix Marseille Université, Centrale Marseille; CNRS, iSm2 UMR 7313; 13397 Marseille France
| | - Cyril Bressy
- Aix Marseille Université, Centrale Marseille; CNRS, iSm2 UMR 7313; 13397 Marseille France
| |
Collapse
|
20
|
Li BS, Wang Y, Jin Z, Chi YR. Cycloaddition of cyclobutenone and azomethine imine enabled by chiral isothiourea organic catalysts. Chem Sci 2015; 6:6008-6012. [PMID: 29449914 PMCID: PMC5669243 DOI: 10.1039/c5sc01972a] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 07/18/2015] [Indexed: 11/21/2022] Open
Abstract
The addition of an organic catalyst to the ketone moiety of a γ-mono-chloride substituted cyclobutenone destroys its stable, conjugated and nearly planar structure. The C-C bond in the resulting less stable anionic oxy-substituted non-planar intermediate is then activated. The breaking of one C-C single bond leads to a catalyst-bound intermediate that undergoes α-carbon selective reactions with azomethine imines to afford nitrogen-containing heterocyclic compounds with excellent diastereo- and enantio-selectivities. Our organocatalytic approach provides a new reaction pattern for C-C bond activation of cyclobutenones that is unavailable with transition metal catalysis. In addition, the present study with isothioureas as the organocatalysts expands the potential in using organocatalysts for C-C bond breaking and selective reactions.
Collapse
Affiliation(s)
- Bao-Sheng Li
- Division of Chemistry & Biological Chemistry , School of Physical & Mathematical Sciences , Nanyang Technological University , Singapore , 637371 , Singapore .
| | - Yuhuang Wang
- Division of Chemistry & Biological Chemistry , School of Physical & Mathematical Sciences , Nanyang Technological University , Singapore , 637371 , Singapore .
| | - Zhichao Jin
- Division of Chemistry & Biological Chemistry , School of Physical & Mathematical Sciences , Nanyang Technological University , Singapore , 637371 , Singapore .
| | - Yonggui Robin Chi
- Division of Chemistry & Biological Chemistry , School of Physical & Mathematical Sciences , Nanyang Technological University , Singapore , 637371 , Singapore .
- State Key Laboratory Breeding Base of Green Pesticide and Agricultural Bioengineering , Ministry of Education , Guizhou University , Guiyang , 550025 , China
| |
Collapse
|
21
|
Barbero M, Buscaino R, Cadamuro S, Dughera S, Gualandi A, Marabello D, Cozzi PG. Synthesis of bench-stable diarylmethylium tetrafluoroborates. J Org Chem 2015; 80:4791-6. [PMID: 25867788 DOI: 10.1021/acs.joc.5b00418] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A representative number of bench-stable nonsymmetric diarylcarbenium tetrafluoroborates have been isolated via the direct coupling of aryl (or heteroaryl) aldehydes and N-heteroarenes and fully characterized. They have proven to be highly stable in the presence of both EDG and EWG substituents. An (E)-iminium vinylogous substructure has been shown as the common cation scaffold by X-ray analysis and by NOE determination.
Collapse
Affiliation(s)
- Margherita Barbero
- †Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125 Torino, Italy
| | - Roberto Buscaino
- †Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125 Torino, Italy
| | - Silvano Cadamuro
- †Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125 Torino, Italy
| | - Stefano Dughera
- †Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125 Torino, Italy
| | - Andrea Gualandi
- ‡Dipartimento di Chimica "G. Ciamician", Alma Mater Studiorum, Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
| | - Domenica Marabello
- §Dipartimento di Chimica e CrisDi (Interdepartmental Center for Crystallography), Università di Torino, Via P. Giuria 7, 10125 Torino, Italy
| | - Pier Giorgio Cozzi
- ‡Dipartimento di Chimica "G. Ciamician", Alma Mater Studiorum, Università di Bologna, Via Selmi 2, 40126 Bologna, Italy
| |
Collapse
|
22
|
Holland MC, Gilmour R. Deconstructing Covalent Organocatalysis. Angew Chem Int Ed Engl 2015; 54:3862-71. [DOI: 10.1002/anie.201409004] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Indexed: 01/15/2023]
|
23
|
|
24
|
Mayr H, Ammer J, Baidya M, Maji B, Nigst TA, Ofial AR, Singer T. Scales of Lewis basicities toward C-centered Lewis acids (carbocations). J Am Chem Soc 2015; 137:2580-99. [PMID: 25555037 DOI: 10.1021/ja511639b] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Equilibria for the reactions of benzhydryl cations (Ar2CH(+)) with phosphines, tert-amines, pyridines, and related Lewis bases were determined photometrically in CH2Cl2 and CH3CN solution at 20 °C. The measured equilibrium constants can be expressed by the sum of two parameters, defined as the Lewis Acidity (LA) of the benzhydrylium ions and the Lewis basicity (LB) of the phosphines, pyridines, etc. Least-squares minimization of log K = LA + LB with the definition LA = 0 for (4-MeOC6H4)2CH(+) gave a Lewis acidity scale for 18 benzhydrylium ions covering 18 orders of magnitude in CH2Cl2 as well as Lewis basicities (with respect to C-centered Lewis acids) for 56 bases. The Lewis acidities correlated linearly with the quantum chemically calculated (B3LYP/6-311++G(3df,2pd)//B3LYP/6-31G(d,p) level) methyl anion affinities of the corresponding benzhydrylium ions, which can be used as reference compounds for characterizing a wide variety of Lewis bases. The equilibrium measurements were complemented by isothermal titration calorimetry studies. Rates of SN1 solvolyses of benzhydryl chlorides, bromides, and tosylates derived from E(13-33)(+), i.e., from highly reactive carbocations, correlate excellently with the corresponding Lewis acidities and the quantum chemically calculated methyl anion affinities. This correlation does not hold for solvolyses of derivatives of the better stabilized amino-substituted benzhydrylium ions E(1-12)(+). In contrast, the correlation between electrophilic reactivities and Lewis acidities (or methyl anion affinities) is linear for all donor-substituted benzhydrylium ions E(1-21)(+), while the acceptor-substituted benzhydrylium ions E(26-33)(+) react more slowly than expected from their thermodynamic stabilities. The boundaries of linear rate-equilibrium relationships were thus defined.
Collapse
Affiliation(s)
- Herbert Mayr
- Department Chemie, Ludwig-Maximilians-Universität München , Butenandtstraße 5-13, Haus F, 81377 München, Germany
| | | | | | | | | | | | | |
Collapse
|
25
|
Zhang X, Waymouth RM. Zwitterionic Ring Opening Polymerization with Isothioureas. ACS Macro Lett 2014; 3:1024-1028. [PMID: 35610786 DOI: 10.1021/mz500525n] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Bicyclic isothioureas 1 and 2 mediate controlled ring opening polymerizations (ROP) of lactides in the absence of protic initiators to afford high molecular weight polylactides (PLA) with narrow polydispersities. The cyclic structure of the resulting PLA was determined by dilute solution viscosity measurement and MALDI-TOF mass spectrometry. Compared to DBU initiator, isothioureas are more selective for producing cyclic PLA without appreciable linear contaminants. Mechanistic studies involving acyl amidinium support our hypothesis that DBU-initiated ZROP generates linear chains from a ketene aminal intermediate.
Collapse
Affiliation(s)
- Xiangyi Zhang
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States
| | - Robert M. Waymouth
- Department of Chemistry, Stanford University, Stanford, California 94305-5080, United States
| |
Collapse
|
26
|
Okamoto S, Sakai Y, Watanabe S, Nishi S, Yoneyama A, Katsumata H, Kosaki Y, Sato R, Shiratori M, Shibuno M, Shishido T. Structure–activity relationship of dihydroimidazo-, dihydropyrimido, tetrahydrodiazepino-[2,1-b]-thiazoles, and -benzothiazoles as an acylation catalyst. Tetrahedron Lett 2014. [DOI: 10.1016/j.tetlet.2014.01.135] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
|
27
|
Brown HA, Waymouth RM. Zwitterionic ring-opening polymerization for the synthesis of high molecular weight cyclic polymers. Acc Chem Res 2013; 46:2585-96. [PMID: 23789724 DOI: 10.1021/ar400072z] [Citation(s) in RCA: 189] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Cyclic polymers are an intriguing class of macromolecules. Because of the constraints of the cyclic topology and the absence of chain ends, the properties of these molecules differ from those of linear polymers in ways that remain poorly understood. Cyclic polymers present formidable synthetic challenges because the entropic penalty of coupling the chain ends grows exponentially with increasing molecular weight. In this Account, we describe recent progress in the application of zwitterionic ring-opening polymerization (ZROP) as a strategy for the synthesis of high molecular weight, cyclic polymers. Zwitterionic ring-opening polymerization involves the addition of neutral organic nucleophiles to strained heterocyclic monomers; under appropriate conditions, cyclization of the resultant macrozwitterions generates cyclic macromolecules. We discuss the mechanistic and kinetic features of these zwitterionic ring-opening reactions and the conditions that influence the efficiency of the initiation, propagation, and cyclization to generate high molecular weight cyclic polymers. N-Heterocyclic carbenes (NHC) are potent nucleophiles and relatively poor leaving groups, two features that are important for the generation of high molecular weight polymers. Investigations of the nature of the monomer and nucleophile have helped researchers understand the factors that govern the reactivity of these systems and their impact on the molecular weight and molecular weight distributions of the resulting cyclic polymers. We focus primarily on ZROP mediated by N-heterocyclic carbene nucleophiles but also discuss zwitterionic polymerizations with amidine, pyridine, and imidazole nucleophiles. The ZROP of N-carboxyanhydrides with N-hetereocyclic carbenes generates a family of functionalized cyclic polypeptoids. We can synthesize gradient lactone copolymers by exploiting differences in relative reactivity present in ZROP that differ from those of traditional metal-mediated polymerizations. These new synthetic methods have allowed us to investigate the influence of topology on the crystallization behavior, stereocomplexation, and solution properties of cyclic macromolecules.
Collapse
Affiliation(s)
- Hayley A. Brown
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Robert M. Waymouth
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| |
Collapse
|
28
|
Maji B, Baidya M, Ammer J, Kobayashi S, Mayer P, Ofial AR, Mayr H. Nucleophilic Reactivities and Lewis Basicities of 2-Imidazolines and Related N-Heterocyclic Compounds. European J Org Chem 2013. [DOI: 10.1002/ejoc.201300213] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
29
|
Mittal N, Sun DX, Seidel D. Kinetic Resolution of Amines via Dual Catalysis: Remarkable Dependence of Selectivity on the Achiral Cocatalyst. Org Lett 2012; 14:3084-7. [DOI: 10.1021/ol301155b] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Nisha Mittal
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Diana X. Sun
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Daniel Seidel
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| |
Collapse
|
30
|
|
31
|
Barbero M, Cadamuro S, Cauda F, Dughera S, Gervasio G, Venturello P. Preparation and Characterization of Aryl or Heteroaryl(3-indolyl)methylium o-Benzenedisulfonimides. J Org Chem 2012; 77:4278-87. [DOI: 10.1021/jo300099y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Margherita Barbero
- Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125
Torino, Italy
| | - Silvano Cadamuro
- Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125
Torino, Italy
| | - Fabrizio Cauda
- Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125
Torino, Italy
| | - Stefano Dughera
- Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125
Torino, Italy
| | - Giuliana Gervasio
- Dipartimento
di Chimica e CrisDi (Centro Interdipartimentale di Cristallografia
Diffrattometrica), Università di Torino, Via P. Giuria 7, 10125 Torino, Italy
| | - Paolo Venturello
- Dipartimento di Chimica, Università di Torino, Via P. Giuria 7, 10125
Torino, Italy
| |
Collapse
|
32
|
Joannesse C, Johnston CP, Morrill LC, Woods PA, Kieffer M, Nigst TA, Mayr H, Lebl T, Philp D, Bragg RA, Smith AD. Isothiourea-Mediated Asymmetric O- to C-Carboxyl Transfer of Oxazolyl Carbonates: Structure-Selectivity Profiles and Mechanistic Studies. Chemistry 2012; 18:2398-408. [DOI: 10.1002/chem.201102847] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2011] [Indexed: 11/07/2022]
|
33
|
Taylor JE, Bull SD, Williams JMJ. Amidines, isothioureas, and guanidines as nucleophilic catalysts. Chem Soc Rev 2012; 41:2109-21. [DOI: 10.1039/c2cs15288f] [Citation(s) in RCA: 355] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
|
34
|
De Rycke N, Couty F, David ORP. Increasing the Reactivity of Nitrogen Catalysts. Chemistry 2011; 17:12852-71. [DOI: 10.1002/chem.201101755] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Indexed: 11/11/2022]
|
35
|
Kalow JA, Doyle AG. Mechanistic investigations of cooperative catalysis in the enantioselective fluorination of epoxides. J Am Chem Soc 2011; 133:16001-12. [PMID: 21863842 DOI: 10.1021/ja207256s] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
This report describes mechanistic studies of the (salen)Co- and amine-cocatalyzed enantioselective ring opening of epoxides by fluoride. The kinetics of the reaction, as determined by in situ (19)F NMR analysis, are characterized by apparent first-order dependence on (salen)Co. Substituent effects, nonlinear effects, and reactivity with a linked (salen)Co catalyst provide evidence for a rate-limiting, bimetallic ring-opening step. To account for these divergent data, we propose a mechanism wherein the active nucleophilic fluorine species is a cobalt fluoride that forms a resting-state dimer. Axial ligation of the amine cocatalyst to (salen)Co facilitates dimer dissociation and is the origin of the observed cooperativity. On the basis of these studies, we show that significant improvements in the rates, turnover numbers, and substrate scope of the fluoride ring-opening reactions can be realized through the use of a linked salen framework. Application of this catalyst system to a rapid (5 min) fluorination to generate the unlabeled analog of a known PET tracer, F-MISO, is reported.
Collapse
Affiliation(s)
- Julia A Kalow
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | | |
Collapse
|
36
|
Maji B, Breugst M, Mayr H. N-Heterocyclic Carbenes: Organocatalysts with Moderate Nucleophilicity but Extraordinarily High Lewis Basicity. Angew Chem Int Ed Engl 2011; 50:6915-9. [DOI: 10.1002/anie.201102435] [Citation(s) in RCA: 158] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Indexed: 11/07/2022]
|