Extractives of Australian timbers. V. Ceanothic acid

Abstract

Further evidence supporting structure (II) for ceanothic acid is given. The isopropenyl side chain has been degraded to yield a trisnorketone; reactions involving the isopropenyl and carboxyl groups attached to ring E and the enlargement of ring E are discussed and a close parallel with the corresponding chemistry of betulic acid is presented. The action of alkali effects isomerizations involving the ring A substituents and this, together with spectroscopic evidence, has been shown to support the stereochemistry assigned to the carboxyl and hydroxyl groups attached to ring A as in (II).