Control of the stereochemistry of C14 hydroxyl during the total synthesis of withanolide E and physachenolide C

M Anees; S Nayak; K Afarinkia; V Vinader

doi:10.1039/c8ra08540d

Control of the stereochemistry of C14 hydroxyl during the total synthesis of withanolide E and physachenolide C

RSC Adv. 2018 Nov 27;8(69):39691-39695. doi: 10.1039/c8ra08540d. eCollection 2018 Nov 23.

Authors

M Anees¹, S Nayak², K Afarinkia¹, V Vinader¹

Affiliations

¹ Institute of Cancer Therapeutics, University of Bradford Bradford BD7 1DP UK m.vinader@bradford.ac.uk.
² School of Chemistry & Biosciences, University of Bradford Bradford BD7 1DP UK.

Abstract

The stereochemical outcome of the epoxidation of Δ_14-15 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.