A novel steroidal aromatization reaction

Abstract

Dehydroisoandrosterone and pregnenolone yield 4-methyloestra-1,3,5(10)-trien-17-one and 4-methyl-19-norpregna-1,3,5(10)-trien-20-one on treatment with 1,3-dibromo-5,5-dimethylhydantoin. Cholesterol affords a mixture of cholesta-2,4,6-triene and 4-methyl-19-norcholesta-1,3,5(10)-triene. In contrast dehydroisoandrosterone acetate affords 3β-acetoxyandrosta-4,6-dien-17-one whilst pregnenolone acetate affords the 5,7-diene. N-Bromosuccinimide is a poorer alternative to the dibromohydantoin.