Terpenoids of the Sonchus. Part III. Sesquiterpene lactones of S. Jacquini D.C., S. pinnatus Ait, and S. radicatus Ait

Abstract

A substance C₁₅H₁₈O₄, isolated from the stems of S. Jacquini D.C., S. pinnatus Ait, and S. radicatus Ait, has been named jacquinelin. Its degradation products suggest an azulenoid structure. From its spectral properties, the presence of a lactone, a ketone in a five-membered ring with two cross-conjugated double bonds, and a primary alcoholic group can be deduced. Based on the hydrogenation products, n.m.r. spectra, and correlation with tetrahydroarbiglovin, the structure of jacquinelin is assigned.