[reaction: see text] Radical cyclization of N-allyl-7-bromo-3a-methyl-hexahydroindol-2-one affords a six-membered ring product that prevails over the isomeric five-membered compound. The former product is generated through two reaction pathways: (a) 6-endo-trig ring closure and (b) rearrangement of an intermediate methylenecyclopentyl radical obtained by 5-exo-trig cyclization.
[反应:见正文] N-烯丙基-7-
溴-3a-甲基-六氢
吲哚-2-酮的自由基环化产生了六元环产物,该六元环产物胜过同分异构的五元化合物。前一种产物通过两个反应途径生成:(a)6-内-trig闭环和(b)通过5-exo-trig环化获得的中间体亚甲基环戊基自由基的重排。