A general method for synthesis of a physiologically important skeleton, perhydro-6H-pyrido[2, 1-i]indole, through cyclization of an active methylene group to an N-acyliminium, was developed. Treatment of the ketoester 5 with BF3·Et2O in methylene chloride resulted in deacetalization of the ethylene acetal group accomapnied with the expected double cyclization to give the tricyclic product 8 in 83% yield, and 8 was smoothly decarbomethoxylated to give decahydro-6H-pyrido[2, 1-i]indole-2, 6-dione (9). The former compound 8 was converted into derivatives of the isoerythroidine skeleton, 14 and 16.
本研究开发了一种通过将活性亚甲基环化为 N-
酰亚胺来合成具有重要生理意义的骨架--全氢-6H-
吡啶并[2,1-i]
吲哚的一般方法。在
二氯甲烷中用
BF3-Et2O 处理
酮酯 5,
乙炔缩醛基团发生脱
乙醛化反应,同时发生预期的双环化反应,得到
三环化合物 8,收率为 83%。前一种化合物 8 被转化成异赤藓
酮类骨架的衍
生物 14 和 16。