Constituents of dipterocarpaceae resins. Part I. Triterpene acids of Dryobalanops aromatica

Abstract

Seven pentacyclic triterpenes were isolated from Dryobalanops aromatica, of which two were artifacts. The structure and stereochemistry at ring A of alphitolic acid was confirmed by a partial synthesis of methyl dihydroalphitolate from betulic acid, which was obtained from Eurya acuminata.