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Formation of the steroidal C-25 chiral center via the asymmetric alkylation methodology†
Yu. V. Ermolovich,V. N. Zhabinskii,V. A. Khripach
Organic & Biomolecular Chemistry Pub Date : 11/03/2014 00:00:00 , DOI:10.1039/C4OB02123A
Abstract

A novel approach for the preparation of steroids containing a chiral center at C-25 is reported. The key stereochemistry inducing step was asymmetric alkylation of pseudoephenamine amides of steroidal C-26 acids. The reaction proceeded with high diastereoselectivity (dr > 99 : 1). The developed methodology was successfully applied to the synthesis of (25R)- and (25S)-cholestenoic acids as well as (25R)- and (25S)-26-hydroxy brassinolides.

Graphical abstract: Formation of the steroidal C-25 chiral center via the asymmetric alkylation methodology
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