METHODS AND COMPOUNDS FOR PREPARING 3ALPHA-OXYGEN SUBSTITUTED STEROIDS

摘要

The invention relates to processes for preparing 3a-O-linked steroids including 3a-O-linked-androst-5-ene steroids and 3a-O-linked-5a-androstane steroids. In one process a 3a,4a-epoxy androst-5-en-17-one is predominately reduced at the epoxy moiety wherein reduction of the 3a,4a epoxy functional group occurs preferentially at position C4 with retention of configuration at position C3 to provide a 3a-O-linked-androst-5-ene steroid. In another process, conditions are provided for inversion of configuration of a 3ß-hydroxy-androst-5-ene steroid by the Mitsunobu reaction to provide a 3a-O-linked-androst-5-ene steroid with reduced amounts of 3a,5a-cycloandrostane side-product impurities.