Synthesis of steroidal cyclopropanes

Abstract

22,23-Methylenestigmast-5-en-3β-ol (IX), 24,25-methylenecholest-5-en-3β-ol (VII) and 24,25-methylene-lanost-8-en-3β-ol (XI) were synthesized by treating stigmasterol, desmosterol, and lanosterol with dichloro-carbene and reducing the adducts (VIII) and (VI) formed. Desmosteryl acetate (V) was synthesized by a novel method from 3β-acetoxychol-5-en-24-oic acid (I), the essential steps being preparation of the diazo-ketone (II), its photochemical Wolff rearrangement to the methyl ester (III), a Grignard reaction of (III) with methylmagnesium iodide and dehydration of the product.