Stereoselective syntheses of 20-epi cholanic acid derivatives from 16-dehydropregnenolone acetate

被引：25

作者：

Shingate, Bapurao B. ^{[1
]}

Hazra, Braja G. ^{[1
]}

Pore, Vandana S. ^{[1
]}

Gonnade, Rajesh G. ^{[2
]}

Bhadbhade, Mohan M. ^{[2
]}

机构：

[1] Natl Chem Lab, Organ Chem Sysnthesis Div, Pune 411008, Maharashtra, India

[2] Natl Chem Lab, Ctr Mat Characterizat, Pune 411008, Maharashtra, India

来源：

TETRAHEDRON | 2007年 / 63卷 / 25期

关键词：

ionic hydrogenation; catalytic hydrogenation; steroidal aldehydes; 20-epi; cholanic acid derivatives; Wittig reaction;

D O I：

10.1016/j.tet.2007.04.014

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

A stereoselective total synthesis of naturally occurring 20-epi cholanic acid derivatives has been realized, starting from readily available 16-dehydropregnenolone acetate. The key step of these syntheses involves an ionic hydrogenation of a C-20,22-ketene dithioacetal and deoxygenation of steroidal C-20 tert-alcohols, to set up the unnatural C(20R) configuration with 100% stereoselectivity. The unnatural C-22 aldehydes with C(20R) stereocenters thus obtained were elaborated to 20-epi cholanic acid derivatives. Two derivatives of 20-epi cholanic acid were synthesized and their structures have been confirmed by single crystal X-ray analysis. Catalytic hydrogenation of 16-dehydropregnenolone acetate and 16-dehydropregnenolone in ethanol affords C-5, C-16 tetrahydro products. Crystal structure analysis of one of these products revealed C-5 alpha and C-17 alpha configurations of the hydrogen atoms. (C) 2007 Elsevier Ltd. All rights reserved.

引用

页码：5622 / 5635

页数：14