Abstract
Homodolichosterone (2) and the related 2-deoxysteroids 9 and 13 were synthesized from (22R, 23R, 24S) -3β-acetoxy-22, 23-epoxy-5α-stigmastan-6-one (3). Reaction of the (22R, 23R) -epoxide 4 with phenylselenyl anion followed by heating with 30% H2O2 afforded a mixture of the allylic alcohols 5 and 6, which were then epoxidized with m-chloroperbenzoic acid. The isolated hydroxyepoxide 7 was heated with aluminum isopropoxide to yield the 3β, 22, 23-triol 9. Acetonide formation of 9 and mesylation gave the sulfonate 10, which was refluxed with lithium carbonate and dimethylformamide and then saponified to give the 3α-ol 11 and the 2, 24 (28) -diene 12. Acid hydrolysis of 11 provided the 3α, 22, 23-triol 13. Selective α-face hydroxylation of 12 with osmium tetroxide and deprotection gave homodolichosterone (2).
