19‐Norsteroide IV. Über die reduktive Ätherspaltung bei 5α‐Halogen‐6β, 19‐oxido‐steroiden. Über Steroide, 198. Mitteilung

Abstract

Abstract The reductive cleavage of the ether bridge of 5α‐chloro‐ and 5α‐bromo‐6β, 19‐oxido‐steroids to 19‐hydroxy‐Δ 5 ‐steroids has been studied : Whereas 5α‐bromo‐6β, 19‐ethers could be reduced under mild conditions, i. e. with zinc and acetic acid, 5α‐chloro‐6β, 19‐ethers could only be cleaved with lithium and liquid ammonia. However, the latter steroids with an additional electronegative substituent in 19‐position, namely 5α‐chloro‐6β, 19‐hemiacetals and ‐lactones, were smoothly converted into Δ 5 ‐19‐aldehydes and Δ 5 ‐19‐acids, respectively, by the action of zinc and acetic acid. The Δ 5 ‐steroid‐3 9‐oic acids obtained could be decarboxylated thermally to Δ 5(10) ‐19‐norsteroids.