Mechanism of the D-Homoannulation of Pregnanediol Disulfate in Refluxing 3N Hydrochloric Acid

概要

論文の詳細を見る
In order to elucidate the mechanism of D-homoannulation of pregnanediol 20-sulfate, solvolysis of [^<13>C-20]-5β-pregnane-3α, 20α-diol disulfate (3) in refluxing 3N hydrochloric acid was investigated. The resulting D-homosteroids, 17α-methyl-D-homo-5β-androstane-3α, 17aβ-diol (8) and 17α-methyl-17aβ-chloro-D-homo-5β-androstan-3α-ol (10), contained a quantitative amount of ^<13>C only at C-17,indicating that the ring-enlargement reaction of the 20α-ol sulfate proceeded with stereospecific migration of the C_<16>-C_<17> bond. The same result was obtained from isomeric [^<13>C-20]-5β-pregnane-3α, 20β-diol disulfate (6). Based on these results, the D-homoannulation of pregnanediol 20-sulfate was concluded to proceed by a stepwise mechanism through the C-20 carbocation. The stereochemistry of this Wagner-Meerwein type rearrangement reaction is also discussed.
1983-11-25