Stereochemically Controlled Synthesis of Steroid Side Chains: Synthesis of Desmosterol

Article abstract of DOI:10.1021/jo01294a056

(20R)-Desmosterol, a versatile intermediate for the synthesis of vitamin D metabolites and numerous other steroids having a side chain modified at C-24 and/or C-25, can be synthesized stereospecifically and efficiently by starting from the readily available 16α,17β-epoxypregnenolone and employing the potassium-assisted oxy-Cope rearrangement as a key stereodirecting process at C-20.