Stereoselective Synthesis of Steroidal (3R)-Spiro-Δ2′-1′,3′,4′-oxadiazoline.

Heterocyclic system namely cholest-5-en-(3R)-spiro-Δ 2 ' -1', 3', 4'-oxadiazoline 3 has been synthesized via the reaction of cholest-5-en-3-one semicarbazone 2 with acetic anhydride and pyridine at 80°C, in high yield. Cholest-5-en-3-one semicarbazone 2 is obtained by the condensation of cholest-5-en-3-one 1 with semicarbazide hydrochloride. The products 2 and 3 are characterized by their physical, analytical and spectral (IR, 1 H NMR) data.