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Han J, Escorihuela J, Fustero S, Landa A, Soloshonok VA, Sorochinsky A. Asymmetric Michael Addition in Synthesis of β-Substituted GABA Derivatives. Molecules 2022; 27:molecules27123797. [PMID: 35744921 PMCID: PMC9231165 DOI: 10.3390/molecules27123797] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 06/07/2022] [Accepted: 06/07/2022] [Indexed: 11/29/2022] Open
Abstract
γ-Aminobutyric acid (GABA) represents one of the most prolific structural units widely used in the design of modern pharmaceuticals. For example, β-substituted GABA derivatives are found in numerous neurological drugs, such as baclofen, phenibut, tolibut, pregabalin, phenylpiracetam, brivaracetam, and rolipram, to mention just a few. In this review, we critically discuss the literature data reported on the preparation of substituted GABA derivatives using the Michael addition reaction as a key synthetic transformation. Special attention is paid to asymmetric methods featuring synthetically useful stereochemical outcomes and operational simplicity.
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Affiliation(s)
- Jianlin Han
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China;
| | - Jorge Escorihuela
- Departamento de Química Orgánica, Universidad de Valencia, 46100 Burjassot, Spain;
| | - Santos Fustero
- Departamento de Química Orgánica, Universidad de Valencia, 46100 Burjassot, Spain;
- Correspondence: (S.F.); (A.S.)
| | - Aitor Landa
- Department of Organic Chemistry I, Faculty of Chemistry, University of the Basque Country UPV/EHU, Paseo Manuel Lardizábal 3, 20018 San Sebastián, Spain; (A.L.); (V.A.S.)
| | - Vadim A. Soloshonok
- Department of Organic Chemistry I, Faculty of Chemistry, University of the Basque Country UPV/EHU, Paseo Manuel Lardizábal 3, 20018 San Sebastián, Spain; (A.L.); (V.A.S.)
- IKERBASQUE, Basque Foundation for Science, Alameda Urquijo 36-5, Plaza Bizkaia, 48011 Bilbao, Spain
| | - Alexander Sorochinsky
- V.P. Kukhar Institute of Bioorganic Chemistry and Petrochemistry, The National Academy of Sciences of Ukraine, 1 Murmanska Str., 02094 Kyiv, Ukraine
- Correspondence: (S.F.); (A.S.)
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2
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Chen W, Fang H, Xie K, Oestreich M. The Cyclohexa-2,5-dienyl Group as a Placeholder for Hydrogen: Organocatalytic Michael Addition of an Acetaldehyde Surrogate. Chemistry 2020; 26:15126-15129. [PMID: 32808731 PMCID: PMC7756304 DOI: 10.1002/chem.202003764] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Indexed: 01/09/2023]
Abstract
An aldehyde with a cyclohexa-2,5-dienyl group in the α-position is introduced as a storable surrogate of highly reactive acetaldehyde. The cyclohexa-2,5-dienyl unit is compatible with an enantioselective Michael addition to nitroalkenes promoted by a Hayashi-Jørgensen catalyst and can be removed by a boron Lewis acid mediated C-C bond cleavage. The robust two-step sequence does not require a large excess of the aldehyde component that is typically needed when directly using acetaldehyde.
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Affiliation(s)
- Weiqiang Chen
- Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623, Berlin, Germany
| | - Huaquan Fang
- Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623, Berlin, Germany
| | - Kaixue Xie
- Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623, Berlin, Germany
| | - Martin Oestreich
- Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 115, 10623, Berlin, Germany
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3
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Alarcón‐Matus E, Alvarado C, Romero‐Ceronio N, Ramos‐Rivera EM, Lobato‐García CE. Proline‐derived Long‐aliphatic‐chain Amphiphilic Organocatalysts (PDLACAOs) for Asymmetric Reactions in Aqueous Media. ASIAN J ORG CHEM 2020. [DOI: 10.1002/ajoc.202000419] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Erika Alarcón‐Matus
- División Académica de Ciencias Básicas Universidad Juárez Autónoma de Tabasco Carretera Cunduacán-Jalpa Km 1, Col. La Esperanza 86690 Cunduacán Tabasco México
| | - Cuauhtémoc Alvarado
- División Académica de Ciencias Básicas Universidad Juárez Autónoma de Tabasco Carretera Cunduacán-Jalpa Km 1, Col. La Esperanza 86690 Cunduacán Tabasco México
| | - Nancy Romero‐Ceronio
- División Académica de Ciencias Básicas Universidad Juárez Autónoma de Tabasco Carretera Cunduacán-Jalpa Km 1, Col. La Esperanza 86690 Cunduacán Tabasco México
| | - Erika M. Ramos‐Rivera
- División Académica de Ciencias Básicas Universidad Juárez Autónoma de Tabasco Carretera Cunduacán-Jalpa Km 1, Col. La Esperanza 86690 Cunduacán Tabasco México
| | - Carlos E. Lobato‐García
- División Académica de Ciencias Básicas Universidad Juárez Autónoma de Tabasco Carretera Cunduacán-Jalpa Km 1, Col. La Esperanza 86690 Cunduacán Tabasco México
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Prabhakara MD, Maiti B. Ionic liquid-immobilized proline(s) organocatalyst-catalyzed one-pot multi-component Mannich reaction under solvent-free condition. RESEARCH ON CHEMICAL INTERMEDIATES 2020. [DOI: 10.1007/s11164-020-04096-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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5
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Guo C, Saifuddin M, Saravanan T, Sharifi M, Poelarends GJ. Biocatalytic Asymmetric Michael Additions of Nitromethane to α,β-Unsaturated Aldehydes via Enzyme-bound Iminium Ion Intermediates. ACS Catal 2019; 9:4369-4373. [PMID: 31080691 PMCID: PMC6503466 DOI: 10.1021/acscatal.9b00780] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 04/09/2019] [Indexed: 11/29/2022]
Abstract
The enzyme 4-oxalocrotonate tautomerase (4-OT) exploits an N-terminal proline as main catalytic residue to facilitate several promiscuous C-C bond-forming reactions via enzyme-bound enamine intermediates. Here we show that the active site of this enzyme can give rise to further synthetically useful catalytic promiscuity. Specifically, the F50A mutant of 4-OT was found to efficiently promote asymmetric Michael additions of nitromethane to various α,β-unsaturated aldehydes to give γ-nitroaldehydes, important precursors to biologically active γ-aminobutyric acids. High conversions, high enantiocontrol, and good isolated product yields were achieved. The reactions likely proceed via iminium ion intermediates formed between the catalytic Pro-1 residue and the α,β-unsaturated aldehydes. In addition, a cascade of three 4-OT(F50A)-catalyzed reactions followed by an enzymatic oxidation step enables assembly of γ-nitrocarboxylic acids from three simple building blocks in one pot. Our results bridge organo- and biocatalysis, and they emphasize the potential of enzyme promiscuity for the preparation of important chiral synthons.
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Affiliation(s)
- Chao Guo
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Mohammad Saifuddin
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Thangavelu Saravanan
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Masih Sharifi
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
| | - Gerrit J. Poelarends
- Department of Chemical and Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV Groningen, The Netherlands
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6
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Li LX, Dong DQ, Hao SH, Wang ZL. Direct sulfonylation of pyrazolones with sodium sulfinates catalyzed by TBAI in water. Tetrahedron Lett 2018. [DOI: 10.1016/j.tetlet.2018.03.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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7
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8
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Mandal T, Kuo W, Su M, Bhowmick K, Zhao JCG. Prolinal dithioacetals: Highly efficient organocatalysts for the direct nitro-Michael additions in both organic and aqueous media. Tetrahedron 2017. [DOI: 10.1016/j.tet.2017.10.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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9
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Huang WL, Raja A, Hong BC, Lee GH. Organocatalytic Enantioselective Michael–Acetalization–Reduction–Nef Reaction for a One-Pot Entry to the Functionalized Aflatoxin System. Total Synthesis of (−)- Dihydroaflatoxin D2 and (−)- and (+)-Microminutinin. Org Lett 2017; 19:3494-3497. [DOI: 10.1021/acs.orglett.7b01473] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wei-Lun Huang
- Department
of Chemistry and Biochemistry, National Chung Cheng University, Chia-Yi 621, Taiwan, R.O.C
| | - Arun Raja
- Department
of Chemistry and Biochemistry, National Chung Cheng University, Chia-Yi 621, Taiwan, R.O.C
| | - Bor-Cherng Hong
- Department
of Chemistry and Biochemistry, National Chung Cheng University, Chia-Yi 621, Taiwan, R.O.C
| | - Gene-Hsiang Lee
- Department
of Chemistry, National Taiwan University, Taipei 106, Taiwan, R.O.C
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10
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van der Meer JY, Poddar H, Baas BJ, Miao Y, Rahimi M, Kunzendorf A, van Merkerk R, Tepper PG, Geertsema EM, Thunnissen AMWH, Quax WJ, Poelarends GJ. Using mutability landscapes of a promiscuous tautomerase to guide the engineering of enantioselective Michaelases. Nat Commun 2016; 7:10911. [PMID: 26952338 PMCID: PMC4786785 DOI: 10.1038/ncomms10911] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 02/02/2016] [Indexed: 01/24/2023] Open
Abstract
The Michael-type addition reaction is widely used in organic synthesis for carbon–carbon bond formation. However, biocatalytic methodologies for this type of reaction are scarce, which is related to the fact that enzymes naturally catalysing carbon–carbon bond-forming Michael-type additions are rare. A promising template to develop new biocatalysts for carbon–carbon bond formation is the enzyme 4-oxalocrotonate tautomerase, which exhibits promiscuous Michael-type addition activity. Here we present mutability landscapes for the expression, tautomerase and Michael-type addition activities, and enantioselectivity of 4-oxalocrotonate tautomerase. These maps of neutral, beneficial and detrimental amino acids for each residue position and enzyme property provide detailed insight into sequence–function relationships. This offers exciting opportunities for enzyme engineering, which is illustrated by the redesign of 4-oxalocrotonate tautomerase into two enantiocomplementary ‘Michaelases'. These ‘Michaelases' catalyse the asymmetric addition of acetaldehyde to various nitroolefins, providing access to both enantiomers of γ-nitroaldehydes, which are important precursors for pharmaceutically active γ-aminobutyric acid derivatives. The Michael-type addition reaction is used for carbon-carbon bond formation; however biocatalytic methods for this reaction are rare. Here, the authors generate and exploit mutability landscapes of 4-oxalocrotonate tautomerase to direct the redesign of this promiscuous enzyme into enantio-complementary Michaelases.
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Affiliation(s)
- Jan-Ytzen van der Meer
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Harshwardhan Poddar
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Bert-Jan Baas
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Yufeng Miao
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Mehran Rahimi
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Andreas Kunzendorf
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Ronald van Merkerk
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Pieter G Tepper
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Edzard M Geertsema
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Andy-Mark W H Thunnissen
- Department of Biophysical Chemistry, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 7, Groningen 9747 AG, The Netherlands
| | - Wim J Quax
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
| | - Gerrit J Poelarends
- Department of Pharmaceutical Biology, Groningen Research Institute of Pharmacy, University of Groningen, Antonius Deusinglaan 1, Groningen 9713 AV, The Netherlands
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Abstract
A novel approach for the synthesis of (S)-nakinadine B, a marine natural product is described. The synthesis utilizes the optimized combination of organocatalyzed Michael addition and aminoxylation reactions as key steps.
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Affiliation(s)
- Yuvraj Garg
- School of Chemistry and Biochemistry
- Thapar University
- Patiala 147001
- India
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12
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Kim SM, Kim YS, Kim DW, Rios R, Yang JW. Acetaldehyde: A Small Organic Molecule with Big Impact on Organocatalytic Reactions. Chemistry 2015; 22:2214-34. [PMID: 26667963 DOI: 10.1002/chem.201503960] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Indexed: 11/11/2022]
Abstract
Stereocontrolled formation of carbon-carbon and carbon-heteroatom bonds through asymmetric organocatalysis is a formidable challenge for modern synthetic chemistry. Among the most significant contributions to this field are the transformations involving the use of acetaldehyde or α-heteroatom-substituted acetaldehydes for constructing valuable synthons (e.g., amino acid derivatives and hydroxycarbonyl). In this Minireview, versatile (enantioselective) organocatalytic transformations are discussed.
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Affiliation(s)
- Sun Min Kim
- Department of Energy Science, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 440-746, Korea
| | - Young Sug Kim
- Department of Energy Science, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 440-746, Korea
| | - Dong Wan Kim
- Department of Energy Science, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 440-746, Korea
| | - Ramon Rios
- Faculty of Natural and Environmental Science, University of Southampton, Highfield Campus, Southampton, SO17 1BJ, UK.
| | - Jung Woon Yang
- Department of Energy Science, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do, 440-746, Korea.
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13
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Meng XL, Liu T, Sun ZW, Wang JC, Peng FZ, Shao ZH. Asymmetric catalytic conjugate addition of acetaldehyde to nitrodienynes/nitroenynes: applications to the syntheses of (+)-α-lycorane and chiral β-alkynyl acids. Org Lett 2014; 16:3044-7. [PMID: 24811051 DOI: 10.1021/ol501158b] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The catalytic enantioselective conjugate addition of acetaldehyde to polyconjugated substrates, nitrodienynes and nitroenynes, has been accomplished using organocatalysis. Various functionalized 1,3-enynes and propargylic compounds were obtained in moderate to good yields with high enantioselectivity. The synthetic utilities of the conjugate addition reactions have been highlighted in the concise total synthesis of (+)-α-lycorane and the metal-free synthesis of chiral β-alkynyl acids.
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Affiliation(s)
- Xue-Ling Meng
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education, School of Chemical Science and Technology, Yunnan University , Kunming, Yunnan 650091, P. R. China
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14
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Highly efficient asymmetric organocatalytic Michael addition of α,α-disubstituted aldehydes to nitroolefins under solvent-free conditions. Tetrahedron Lett 2014. [DOI: 10.1016/j.tetlet.2014.03.107] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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15
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Kumari K, Allam BK, Singh KN. A simple and sustainable tetrabutylammonium fluoride (TBAF)-catalyzed synthesis of azaarene-substituted 3-hydroxy-2-oxindoles through sp3 C–H functionalization. RSC Adv 2014. [DOI: 10.1039/c3ra47332e] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
A green, practical, and metal-free protocol for direct addition of α-and γ-alkylazaarenes to isatins has been developed for the synthesis of biologically important azaarene-substituted 3-hydroxy-2-oxindoles in good to excellent yields.
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Affiliation(s)
- Kumkum Kumari
- Department of Chemistry
- Faculty of Science
- Banaras Hindu University
- Varanasi 221005, India
| | - Bharat Kumar Allam
- Department of Chemistry
- Faculty of Science
- Banaras Hindu University
- Varanasi 221005, India
| | - Krishna Nand Singh
- Department of Chemistry
- Faculty of Science
- Banaras Hindu University
- Varanasi 221005, India
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Geertsema EM, Miao Y, Tepper PG, de Haan P, Zandvoort E, Poelarends GJ. Biocatalytic Michael-Type Additions of Acetaldehyde to Nitroolefins with the Proline-Based Enzyme 4-Oxalocrotonate Tautomerase Yielding Enantioenriched γ-Nitroaldehydes. Chemistry 2013; 19:14407-10. [DOI: 10.1002/chem.201302351] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Indexed: 12/26/2022]
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17
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Scheffler U, Mahrwald R. Recent Advances in Organocatalytic Methods for Asymmetric CC Bond Formation. Chemistry 2013; 19:14346-96. [DOI: 10.1002/chem.201301996] [Citation(s) in RCA: 178] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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19
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Fan X, Rodríguez-Escrich C, Sayalero S, Pericàs MA. Paraldehyde as an Acetaldehyde Precursor in Asymmetric Michael Reactions Promoted by Site-Isolated Incompatible Catalysts. Chemistry 2013; 19:10814-7. [DOI: 10.1002/chem.201302087] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Indexed: 11/10/2022]
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Qiao Y, Chen Q, Lin S, Ni B, Headley AD. Organocatalytic Direct Asymmetric Crossed-Aldol Reactions of Acetaldehyde in Aqueous Media. J Org Chem 2013; 78:2693-7. [DOI: 10.1021/jo302442g] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Yupu Qiao
- Department
of Chemistry, Texas A&M University-Commerce, Commerce, Texas 75429-3011, United
States
| | - Qiankun Chen
- Department
of Chemistry, Texas A&M University-Commerce, Commerce, Texas 75429-3011, United
States
| | - Sirong Lin
- Department
of Chemistry, Texas A&M University-Commerce, Commerce, Texas 75429-3011, United
States
| | - Bukuo Ni
- Department
of Chemistry, Texas A&M University-Commerce, Commerce, Texas 75429-3011, United
States
| | - Allan D. Headley
- Department
of Chemistry, Texas A&M University-Commerce, Commerce, Texas 75429-3011, United
States
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Ghosh SK, Qiao Y, Ni B, Headley AD. Asymmetric Michael reactions catalyzed by a highly efficient and recyclable quaternary ammonium ionic liquid-supported organocatalyst in aqueous media. Org Biomol Chem 2013; 11:1801-4. [DOI: 10.1039/c3ob27398a] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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