Pentacyclic steroids. Part 1. Synthesis and X-ray conformational analysis of 4α,5β- and 4α,5β-dihydrobenzo[4,5,6]cholestan-5′(6′H)-one

Abstract

Conjugate alkylation of cholest-4-en-6-one (1) with the homocuprate derived from the reaction of lithiated acetone NN-dimethylhydrazone with copper(I) iodide, followed by acidic hydrolysis, afforded 4β-(2-oxopropyl)-5α- and -5β-cholestan-6-one (3) and (4). The latter compound underwent intramolecular aldol condensation, and the derived hydroxy ketone was converted into 4α,5β- and 4α,5β-dihydrobenzo[4,5,6]cholest-4-en-5′(6′H)-one (9) and (10), the structures and conformations of which were investigated by X-ray crystallography.