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Bitai J, Westwood MT, Smith AD. α,β-Unsaturated acyl ammonium species as reactive intermediates in organocatalysis: an update. Org Biomol Chem 2021; 19:2366-2384. [PMID: 33650626 DOI: 10.1039/d0ob02208j] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
α,β-Unsaturated acyl ammonium species are versatile intermediates that have been applied in a variety of transformations including Michael additions, domino reactions and cycloadditions. Many of these transformations are promoted by chiral Lewis base catalysts, enabling the rapid generation of molecular complexity with high stereochemical control. This review highlights recent developments in the generation and application of α,β-unsaturated acyl ammonium intermediates reported since a previous review of this area in 2016. Particular emphasis will be placed on reports providing mechanistic insight into catalytic transformations and observed selectivities. A perspective on current challenges and potential future developments in the field of α,β-unsaturated acyl ammonium catalysis is also provided.
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Affiliation(s)
- Jacqueline Bitai
- EaStCHEM, School of Chemistry, University of St Andrews, North Haugh, Fife, Scotland, KY16 9ST, UK.
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2
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Zhang YC, Geng RL, Song J, Gong LZ. Isothiourea and Brønsted Acid Cooperative Catalysis: Enantioselective Construction of Dihydropyridinones. Org Lett 2020; 22:2261-2265. [DOI: 10.1021/acs.orglett.0c00461] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Yu-Chen Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Rui-Long Geng
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Jin Song
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
| | - Liu-Zhu Gong
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China
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Shu C, Liu H, Slawin AMZ, Carpenter-Warren C, Smith AD. Isothiourea-catalysed enantioselective Michael addition of N-heterocyclic pronucleophiles to α,β-unsaturated aryl esters. Chem Sci 2019; 11:241-247. [PMID: 34040717 PMCID: PMC8133005 DOI: 10.1039/c9sc04303a] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The isothiourea-catalysed enantioselective Michael addition of 3-aryloxindole and 4-substituted-dihydropyrazol-3-one pronucleophiles to α,β-unsaturated p-nitrophenyl esters is reported. This process generates products containing two contiguous stereocentres, one quaternary, in good yields and excellent enantioselectivities (>30 examples, up to > 95 : 5 dr and 99 : 1 er). This protocol harnesses the multifunctional ability of p-nitrophenoxide to promote effective catalysis. In contrast to previous methodologies using tertiary amine Lewis bases, in which the pronucleophile was used as the solvent, this work allows bespoke pronucleophiles to be used in stoichiometric quantities. The isothiourea-catalysed enantioselective Michael addition of 3-aryloxindole and 4-substituted-dihydropyrazol-3-one pronucleophiles to α,β-unsaturated p-nitrophenyl esters is reported.![]()
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Affiliation(s)
- Chang Shu
- EaStCHEM, School of Chemistry, University of St Andrews North Haugh, St Andrews Fife KY16 9ST UK
| | - Honglei Liu
- EaStCHEM, School of Chemistry, University of St Andrews North Haugh, St Andrews Fife KY16 9ST UK
| | - Alexandra M Z Slawin
- EaStCHEM, School of Chemistry, University of St Andrews North Haugh, St Andrews Fife KY16 9ST UK
| | - Cameron Carpenter-Warren
- EaStCHEM, School of Chemistry, University of St Andrews North Haugh, St Andrews Fife KY16 9ST UK
| | - Andrew D Smith
- EaStCHEM, School of Chemistry, University of St Andrews North Haugh, St Andrews Fife KY16 9ST UK
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Enantioselective synthesis of indolo[2,3-b]-dihydrothiopyranones via [3+3] cycloaddition of chiral α,β-unsaturated acylammonium salts. Tetrahedron 2018. [DOI: 10.1016/j.tet.2018.09.024] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Kang G, Yamagami M, Vellalath S, Romo D. Enantioselective Synthesis of Medium‐Sized Lactams via Chiral α,β‐Unsaturated Acylammonium Salts. Angew Chem Int Ed Engl 2018. [DOI: 10.1002/ange.201802483] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Guowei Kang
- Department of Chemistry and Biochemistry Baylor University One Bear Place #97348 Waco TX 76798-7348 USA
| | - Masaki Yamagami
- Biomolecular Chemistry Laboratory Department of Chemistry Graduate School of Science 1-1 Machikaneyama, Toyonaka Osaka 560-0043 Japan
| | - Sreekumar Vellalath
- Department of Chemistry and Biochemistry Baylor University One Bear Place #97348 Waco TX 76798-7348 USA
| | - Daniel Romo
- Department of Chemistry and Biochemistry Baylor University One Bear Place #97348 Waco TX 76798-7348 USA
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Kang G, Yamagami M, Vellalath S, Romo D. Enantioselective Synthesis of Medium-Sized Lactams via Chiral α,β-Unsaturated Acylammonium Salts. Angew Chem Int Ed Engl 2018; 57:6527-6531. [PMID: 29624841 DOI: 10.1002/anie.201802483] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Indexed: 11/12/2022]
Abstract
Medium-sized lactams are important structural motifs found in a variety of bioactive compounds and natural products but are challenging to prepare, especially in optically active form. A Michael addition/proton transfer/lactamization organocascade process is described that delivers medium-sized lactams, including azepanones, benzazepinones, azocanones, and benzazocinones, in high enantiopurity through the intermediacy of chiral α,β-unsaturated acylammonium salts. An unexpected indoline synthesis was also uncovered, and the benzazocinone skeleton was transformed into other complex heterocyclic derivatives, including spiroglutarimides, isoquinolinones, and δ-lactones.
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Affiliation(s)
- Guowei Kang
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798-7348, USA
| | - Masaki Yamagami
- Biomolecular Chemistry Laboratory, Department of Chemistry, Graduate School of Science, 1-1 Machikaneyama, Toyonaka, Osaka, 560-0043, Japan
| | - Sreekumar Vellalath
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798-7348, USA
| | - Daniel Romo
- Department of Chemistry and Biochemistry, Baylor University, One Bear Place #97348, Waco, TX, 76798-7348, USA
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Van KN, Romo D. Multicomponent, Enantioselective Michael-Michael-Aldol-β-Lactonizations Delivering Complex β-Lactones. J Org Chem 2018; 83:632-643. [PMID: 29219311 DOI: 10.1021/acs.joc.7b02543] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Optically active, tertiary amine Lewis bases react with unsaturated acid chlorides to deliver chiral, α,β-unsaturated acylammonium salts. These intermediates participate in a catalytic, enantioselective, three-component process delivering bi- and tricyclic β-lactones through a Michael-Michael-aldol-β-lactonization. In a single operation, the described multicomponent, organocascade process forms complex bi- and tricyclic β-lactones by generating four new bonds, two rings, and up to four contiguous stereocenters. In the racemic series, yields of 22-75% were achieved using 4-pyrrolidinopyridine as Lewis base. In the enantioselective series employing isothiourea catalysts, a kinetic resolution of the initially formed racemic Michael adduct appears operative, providing yields of 46% to quantitative (based on 50% max) with up to 94:6 er. Some evidence for a dynamic kinetic asymmetric transformation for tricyclic-β-lactone 1d was obtained following optimization (yields up to 61%, 94:6 er) through a presumed reversible Michael.
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Affiliation(s)
- Khoi N Van
- Department of Chemistry, Texas A&M University , College Station, Texas 77842, United States
| | - Daniel Romo
- Department of Chemistry & Biochemistry, Baylor University , Waco, Texas 76798, United States
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Shimada K, Taneichi Y, Korenaga T. A Short-Step Synthesis of Onychine and the Related 4-Azafluorenones via Hetero Diels-Alder Reaction of 5-Substituted Isotellurazoles. HETEROCYCLES 2018. [DOI: 10.3987/com-17-13865] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Matviitsuk A, Taylor JE, Cordes DB, Slawin AMZ, Smith AD. Enantioselective Stereodivergent Nucleophile-Dependent Isothiourea-Catalysed Domino Reactions. Chemistry 2016; 22:17748-17757. [PMID: 27727506 PMCID: PMC5132085 DOI: 10.1002/chem.201603318] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Indexed: 11/12/2022]
Abstract
α,β-Unsaturated acyl ammoniums generated from the reaction of α,β-unsaturated 2,4,6-trichlorophenol (TCP) esters bearing a pendent enone with an isothiourea organocatalyst are versatile intermediates in a range of enantioselective nucleophile-dependent domino processes to form complex products of diverse topology with excellent stereoselectivity. Use of either 1,3-dicarbonyls, acyl benzothiazoles, or acyl benzimidazoles as nucleophiles allows three distinct, diastereodivergent domino reaction pathways to be accessed to form various fused polycyclic cores containing multiple contiguous stereocentres.
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Affiliation(s)
- Anastassia Matviitsuk
- EaStCHEMSchool of ChemistryUniversity of St. Andrews, North HaughSt. AndrewsFifeKY16 9STUK
| | - James E. Taylor
- EaStCHEMSchool of ChemistryUniversity of St. Andrews, North HaughSt. AndrewsFifeKY16 9STUK
| | - David B. Cordes
- EaStCHEMSchool of ChemistryUniversity of St. Andrews, North HaughSt. AndrewsFifeKY16 9STUK
| | - Alexandra M. Z. Slawin
- EaStCHEMSchool of ChemistryUniversity of St. Andrews, North HaughSt. AndrewsFifeKY16 9STUK
| | - Andrew D. Smith
- EaStCHEMSchool of ChemistryUniversity of St. Andrews, North HaughSt. AndrewsFifeKY16 9STUK
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Vellalath S, Romo D. Asymmetric Organocatalysis: The Emerging Utility of α,β-Unsaturated Acylammonium Salts. Angew Chem Int Ed Engl 2016; 55:13934-13943. [PMID: 27650693 PMCID: PMC5523468 DOI: 10.1002/anie.201602217] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Revised: 04/12/2016] [Indexed: 11/06/2022]
Abstract
Although acylammonium salts are well-studied, chiral α,β-unsaturated acylammonium salts have received much less attention. While these intermediates are convenient synthons, which are readily available from several commodity unsaturated acids and acid chlorides, and possess three reactive sites, their application in organic synthesis has been limited because of the lack of appropriate chiral Lewis bases for their generation. In recent years, the utility of chiral, unsaturated acylammonium salts has expanded considerably, thus demonstrating the unique reactivity of this intermediate leading to the development of a diverse array of catalytic, asymmetric transformations including organocascade processes. This Minireview highlights the recent and growing interest in these intermediates which might spark further research into their untapped potential for asymmetric organocascade catalysis. A cursory comparison is made to related unsaturated iminium and acylazolium intermediates.
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Affiliation(s)
- Sreekumar Vellalath
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, 76798, USA
| | - Daniel Romo
- Department of Chemistry and Biochemistry, Baylor University, Waco, TX, 76798, USA.
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Abbasov ME, Hudson BM, Tantillo DJ, Romo D. Stereodivergent, Diels-Alder-initiated organocascades employing α,β-unsaturated acylammonium salts: scope, mechanism, and application. Chem Sci 2016; 8:1511-1524. [PMID: 28616147 PMCID: PMC5460596 DOI: 10.1039/c6sc04273b] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 10/24/2016] [Indexed: 12/16/2022] Open
Abstract
Chiral α,β-unsaturated acylammonium salts are novel dienophiles enabling enantioselective Diels–Alder-lactonization (DAL) organocascades leading to cis- and trans-fused, bicyclic γ- and δ-lactones.
Chiral α,β-unsaturated acylammonium salts are novel dienophiles enabling enantioselective Diels–Alder-lactonization (DAL) organocascades leading to cis- and trans-fused, bicyclic γ- and δ-lactones from readily prepared dienes, commodity acid chlorides, and a chiral isothiourea organocatalyst under mild conditions. We describe extensions of stereodivergent DAL organocascades to other racemic dienes bearing pendant secondary and tertiary alcohols, and application to a formal synthesis of (+)-dihydrocompactin is described. A combined experimental and computational investigation of unsaturated acylammonium salt formation and the entire DAL organocascade pathway provide a rationalization of the effect of Brønsted base additives and enabled a controllable, diastereodivergent DAL process leading to a full complement of possible stereoisomeric products. Evaluation of free energy and enthalpy barriers in conjunction with experimentally observed temperature effects revealed that the DAL is a rare case of an entropy-controlled diastereoselective process. NMR analysis of diene alcohol–Brønsted base interactions and computational studies provide a plausible explanation of observed stabilization of exo transition-state structures through hydrogen-bonding effects.
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Affiliation(s)
- Mikail E Abbasov
- Department of Chemistry and Biochemistry , Baylor University , One Bear Place 97348 , Waco , Texas 76798 , USA
| | - Brandi M Hudson
- Department of Chemistry , University of California-Davis , One Shields Avenue , Davis , California 95616 , USA .
| | - Dean J Tantillo
- Department of Chemistry , University of California-Davis , One Shields Avenue , Davis , California 95616 , USA .
| | - Daniel Romo
- Department of Chemistry and Biochemistry , Baylor University , One Bear Place 97348 , Waco , Texas 76798 , USA
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Vellalath S, Romo D. Asymmetrische Organokatalyse: α,β‐ungesättigte Acylammoniumsalze erweisen sich als immer nützlicher. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201602217] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Sreekumar Vellalath
- Department of Chemistry and Biochemistry Baylor University Waco TX 76798 USA
| | - Daniel Romo
- Department of Chemistry and Biochemistry Baylor University Waco TX 76798 USA
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