Asymmetrie synthesis of (+)-hinokinin, (+)-dihydrocubebin and cubebin dimethyl ether, a new lignan from Phyllanthus niruri

Abstract

The asymmetric synthesis of the new lignan cubebin dimethyl ether was accomplished in eight steps with an overall yield of 40%. In addition, the known lignans (+)-hinokinin and (+)-dihydrocubebin were synthesized by this route. Our approach involves the highly diastereoselective and enantioselective (de > 98%, ee > 98%) construction of a trans-substituted 2,3- dibenzylbutyrolactone through an asymmetric Michael addition of an enantiopure lithiated aminonitrile to 5H-furan-2-one. © 2007 Verlag der Zeitschrift für Naturforschung.