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.
新的木脂素cubebin二甲醚的不对称合成共经过八步反应,产率总计为40%。此外,已知的木脂素(+)-hinokinin和(+)-dihydrocubebin也通过这个路线被合成。我们的方法包括通过不对称Michael加成反应将手性纯的锂化氨基腈加到5H-呋喃-2-酮上,高度选择性地构建反式取代的2,3-二苯基丁酰内酯(de ≥ 98%,ee ≥ 98%)。