On the Constituents of Linaria japonica MIQ. III. The Structure of Linarienone, a New cis-Clerodane-type Diterpene

Abstract

A new diterpene named linarienone (2) was isolated from the ether-soluble portion of the fresh subterranean part of Linaria japonica MIQ. (Scrophulariaceae). Linarienone (2) is a monoacetyl-monoangeloyl derivative of a 5β-methyl-cis-clerodane-type diterpene and the stereostructure including the absolute configuration has been established as 2 on the basis of the chemical and physicochemical evidence and the unequivocal conversion starting from linarienone (2) and linaridial (1) leading to a common 5β-methyl-cis-clerodane-type hydrocarbon (18).