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Lopes SMM, Gomes CSB, Pinho E Melo TMVD. Reactivity of Steroidal 1-Azadienes toward Carbonyl Compounds under Enamine Catalysis: Chiral Penta- and Hexacyclic Steroids. Org Lett 2018; 20:4332-4336. [PMID: 29984581 DOI: 10.1021/acs.orglett.8b01783] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The synthesis and reactivity of a steroidal N-sulfonyl-1-azadiene, derived from 16-dehydropregnenolone acetate, toward carbonyl compounds under enamine catalysis is disclosed. An unexpected annulation reaction was observed involving an initial stereoselective conjugate addition of the in situ generated enamine to the steroidal 1-azadiene. The developed diastereoselective synthetic methodology is a novel approach to a new class of chiral pentacyclic and hexacyclic steroids.
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Affiliation(s)
- Susana M M Lopes
- CQC and Department of Chemistry , University of Coimbra , 3004-535 Coimbra , Portugal
| | - Clara S B Gomes
- Centro de Química Estrutural, Instituto Superior Técnico , Universidade de Lisboa , Av. Rovisco Pais , 1049-001 Lisboa , Portugal
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Hong L, Ahles S, Heindl AH, Tiétcha G, Petrov A, Lu Z, Logemann C, Wegner HA. An air-stable bisboron complex: a practical bidentate Lewis acid catalyst. Beilstein J Org Chem 2018; 14:618-625. [PMID: 29623123 PMCID: PMC5870160 DOI: 10.3762/bjoc.14.48] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 02/20/2018] [Indexed: 02/05/2023] Open
Abstract
We report an air-stable bisboron complex as an efficient catalyst for the inverse electron-demand Diels–Alder (IEDDA) reaction of 1,2-diazine as well as 1,2,4,5-tetrazine. Its stability towards air and moisture was demonstrated by NMR studies enabling its application in organic transformations without glovebox. A one-pot procedure for its synthesis was developed starting from 1,2-bis(trimethylsilyl)benzene greatly enhancing its practicality. Comparative reactions were carried out to evaluate its catalytic activity in IEDDA reactions of diazine including phthalazine as well as 1,2,4,5-tetrazine.
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Affiliation(s)
- Longcheng Hong
- Institute of Organic Chemistry, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Sebastian Ahles
- Institute of Organic Chemistry, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Andreas H Heindl
- Institute of Organic Chemistry, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Gastelle Tiétcha
- Institute of Organic Chemistry, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Andrey Petrov
- Institute of Organic Chemistry, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Zhenpin Lu
- Institute of Organic Chemistry, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany.,Current position: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, United Kingdom
| | - Christian Logemann
- Institute of Inorganic Chemistry, University of Cologne, Greinstr. 4, 50939 Cologne, Germany
| | - Hermann A Wegner
- Institute of Organic Chemistry, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
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