Williams John R, Gong Hua, Hoff Nathan, Olubodun Olaoluwa I, Carroll Patrick J
Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122-2585, USA.
Org Lett. 2004 Jan 22;6(2):269-71. doi: 10.1021/ol036257u.
[reaction: see text] (25R)-5alpha-cholesta-3beta,16alpha,26-triol 7b and (25R)-5alpha-cholesta-3beta,15alpha,26-triol 10b were synthesized, via (25R)-5alpha-cholesta-3beta,16beta,26-triol 5a, from diosgenin 3 in 52% yield over six steps and 47% yield over eight steps, respectively. An efficient method for inversion of a C-16beta hydroxyl to the C-16alpha position and a short method for transposition of a C-16beta hydroxyl to the C-15alpha position via the unexpected beta-reduction of a C-15 ketone in a steroid are reported.
[反应：见正文] 通过（25R）-5α-胆甾-3β，16β，26-三醇5a，从薯蓣皂苷元3分别以六步52%的产率和八步47%的产率合成了（25R）-5α-胆甾-3β，16α，26-三醇7b和（25R）-5α-胆甾-3β，15α，26-三醇10b。报道了一种将甾体中C-16β羟基转化为C-16α位置的有效方法以及一种通过甾体中C-15酮意外的β-还原将C-16β羟基转位至C-15α位置的简短方法。
