Anees M, Nayak S, Afarinkia K, Vinader V. Control of the stereochemistry of C14 hydroxyl during the total synthesis of withanolide E and physachenolide C.
RSC Adv 2018;
8:39691-39695. [PMID:
35558026 PMCID:
PMC9091292 DOI:
10.1039/c8ra08540d]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 11/16/2018] [Indexed: 11/24/2022] Open
Abstract
The stereochemical outcome of the epoxidation of Δ14–15 cholestanes with mCPBA is controlled by the steric bulk of a C17 substituent. When the C17 is in the β configuration, the epoxide is formed in the α face, whereas if the C17 is trigonal (flat) or the substituent is in the α configuration, the epoxide is formed in the β face. The presence of a hydroxyl substituent at C20 does not influence the stereochemical outcome of the epoxidation.
The epoxide configuration in oxidation of C14–C15 alkenes is determined by the configuration of the C17 substituent.![]()
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