Studies on Lupin Alkaloids. VI. Isolation and Structure of (+)-Isomatrine

Abstract

A new stereoisomer of matrine was isolated from "Ku-Shen, " dry roots of Sophora flavescens, and named (+)-isomatrine. Epimerization of this compound into (+)-matrine (I) demostrated its flamework. X-Ray analysis of (+)-isomatrine hydrobromide was performed and its structure, [5R, 6R, 7S, 11R]-17-oxomatridine (VI), was elucidated. The conformations of A, B, C and D ring in VI are chair, boat, boat and half-chair, respectively.