Preparation of 5α-[3β-2H]cholestan-3α-ol by isomerization reactions

The preparation of 5α-[3β-2H]cholestan-3α-ol by isomerization of the easily accessible 5α-[3α-2H]cholestan-3β-ol was investigated. Isomerization of the mesylate in collidine–water or treatment of the 3β-ol with benzoic acid in the presence of triphenylphosphine and diethyl azodicarboxylate yielded the 3α-isomer with no loss of deuterium from C-3.