Structure and Synthesis of a New Monoterpenoidal Carboxamide from the Seeds of the Thai Medicinal Plant Acacia concinna

A new monoterpenoidal carboxamide, concinnamide (1), has been isolated from the seeds of a Thai medicinal plant, Acacia concinna DC. (Leguminosae). Its structure has been revised to (E)-2, 6-dimethyl-6-hydroxy-2, 7-octadienamide by detailed spectroscopic and synthetic studies, though it had been preliminarily assigned as a seven-membered lactam derivative by our previous work. (-)-Concinnamide, (-)-1, was synthesized from (-)-linalool (2) by stepwise oxidation, followed by amidation to confirm the structure. The inhibitory effects of 1 and related compounds on the arachidonate 5-lipoxygenase of RBL-1 cells are also described.