Constituents of Solidago species. Part VII. Constitution and stereochemistry of the cis-clerodanes from Solidago arguta Ait. and of related diterpenoids

Abstract

Six new diterpenoids, (2a—e) and (4), with a cis-clerodane skeleton and the known trans-clerodane (1) have been isolated from the roots of Solidago arguta. The constitution and stereochemistry of the new compounds are deduced from their spectral properties, a series of interconversions, and the observation that (2a) and the epoxide (13), of well defined structure, can be transformed into the same derivative (14a). The stereochemistry assigned to marrubiaside (27a) has been confirmed by reducing the related ester (27b) to (2c). Comment is made on the stereochemistry of several related, known, clerodanes, including those from S. shortii.