ABCD-ring system of lactonamycin (1) is reported in this Letter. The key step is the tandem cyanide conjugate addition-Dieckmann condensation of alkyne 17 to afford a fully functionalized anthracene. Selective reduction of the cyano group with subsequent lactam formation affords the tetracyclic core of lactonamycin 19. [reaction: see text]
这封信报道了内毒素(1)的AB
CD环系统的有效合成。关键步骤是串联
氰化物共轭加成反应-
炔烃17的Dieckmann缩合反应,以得到完全官能化的
蒽。
氰基的选择性还原以及随后的内酰胺的形成提供了内那霉素19的四环核。