STEROID HORMONES——Ⅱ.ALTERNATIVE ROUTE TO THE SYNTHESIS OF 9α-FLUORO-CORTICOIDS

The method of Ringold and Stork for the introduction of cortical hormone side chain was extended to the 9(11)-unsaturated steroid analogue. Thus, starting from 16α,17α-epoxypregn-4-en-11α-ol-3, 20-dione (Ⅰ), tosylation and elimination of the tosylate group gave 16α, 17α-epoxypregn-4, 9(11)-dien-3, 20-dione (Ⅱ), cleavage of the epoxide ring with hydrobromic acid and debromination by hydrogenolysis gave pregn-4, 9(11)-dien-17α-ol-3, 20-dione (Ⅲ), then introduction of the 21-acetoxy group gave pregn-4, 9(11)-dien-17α, 21-diol-3, 20-dione 21-acetate (Ⅳ), from which 9α-fluorocortisol (Ⅵ) was obtained by known method. The overall yield of (Ⅵ) to (Ⅰ) was 17.4 per cent of theory. An alternative synthesis proceeding through epoxidation of (Ⅲ) prior to the introduction of 21-acetoxy group was also shown to be workable.