STEROIDS AND RELATED PRODUCTS: XVII. THE SYNTHESIS OF 3,9,12,20-TETRAOXYGENATED 9,12-seco-STEROIDS. PART II

Abstract

It is shown that the ozonolysis of Δ9(11)-12-keto steroids with a trans fusion of rings A and B proceeds in better yields than the corresponding opening of ring C in the sterically more hindered A/B-cis series. The syntheses of 23ξ-bromo-3β-hydroxy-9-oxo-9,12-seco-25-iso-5α,22β-spirostan-12-oic acid and some of its derivatives as well as of 3β,20α-dihydroxy-9-oxo-9,12-seco-12-pregnanoic acid and some of its ester derivatives are reported. It is demonstrated that the reduction with lithium aluminum hydride in tetrahydrofuran of a 12,20-diketone leads predominantly to a 12β,20α-dihydroxy derivative, in contradistinction to the reduction of a 12α-acetoxy-20-ketone, which affords mostly the 20β-alcohol.