Steroids—CXX synthesis of halogenated steroid hormones : New routes to 6α-fluorotestosterone and the 6α- and 6β- fluoro analogs of progesterone. The synthesis of 6α- and 6β-fluoro reichstein's compound “S” and 6α- and 6β- fluorodesoxycorticosterone acetate

Abstract

The conformational and electronic factors involved in the fission of steroid 5α,6α-epoxides with boron trifluoride-etherate are discussed with particular reference to C-3-keto-5α,6α-epoxides and their cycloethylene-dioxy derivatives. These considerations led to the development of a new synthesis of 6-fluoro-Δ 4-3-ketones from the corresponding Δ 4-3-ketones via the boron trifluoride-etherate cleavage of their derived cycloethylene-ketal-5α,6α-epoxides. Application of this method led to the synthesis of 6α-fluorotestosterone and the 6α and 6β-fluoro analogs of progesterone desoxycorticosterone acetate and Reichstein's Compound “S” diacetate. The latter compound and its Δ 1-analog are valuable precursors for the 6-fluoro cortical hormones.