Stereoselective synthesis of pentacyclic steroids functionalized at C-11

We set out to describe an efficient and versatile method for preparing pentacyclic steroids diversely substituted at C-11 from cholic acid, via a stereoselective epoxidation and the epoxide opening as the key steps. The characteristic H-1 and C-13 NMR spectroscopic features of the synthesized compounds are reported. (C) 2012 Published by Elsevier Inc.