The synthesis and "round trip radical cyclization" of 11-iodo-2,7,11-trimethyldodec-6-en-5-one are described. The round trip cyclization is a sequence of 5-exo, 6-endo, and 5-exo cyclizations in which the last radical cyclization occurs at the same carbon atom as the initial radical generation. The key second (6-endo) cyclization produces two stereoisomers, one of which cyclizes efficiently to isogymnomitrene
描述了11-
碘-2,7,11-三
甲基十二烷基-6-en-5-one的合成和“往返自由基环化”。往返环化是5-exo,6-endo和5-exo环化的序列,其中最后一个自由基环化发生在与初始自由基生成相同的
碳原子上。关键的第二个(6-endo)环化反应产生了两种立体异构体,其中一种有效地环化为异木香
烯酮,而另一种则低效地环化为裸香
烯酮。影响第二个环化反应的动力学或热力学结果的努力未成功,并且将结果与Jung和Rayle的相关环化反应进行了对比,后者易于建立热力学控制。