Photochemical reactions, 135th communication Photochemistry of Homoconjugated Cyclobutanones. II. Decisive Effect ofgem- Dimethyl Substitution on the Course of the Oxa-di-?-methane Rearrangement
作者:Terry A. Lyle、Hari Babu Mereyala、Alfons Pascual、Bruno Frei
DOI:10.1002/hlca.19840670319
日期:1984.5.2
The synthesis and photolysis of the spirocyclobutanones 4–7 incorporating a cyclohexa-, cyclohepta- and cyclooctadiene moiety, respectively, is described. On triplet excitation, these compounds undergo isomerization via a 1,2-acyl shift involving one or both double bonds of the diene system. The presence of a gem-dimethyl group as in 1, 4 and 7 dramatically changes the photoproduct distribution, since
描述了分别结合有环六- ,环庚-和环辛二烯部分的螺环丁酮4-7的合成和光解作用。在三重激发下,这些化合物通过涉及二烯系统一个或两个双键的1,2-酰基转移进行异构化。一个的存在宝石-二甲基基团作为在1,4和7显着地改变了光化产物的分布,因为只有这些基板通向产品3,29和34从插烯环合所得的(方案5)。那些没有甲基取代的底物(5和6)仅给出涉及一个双键的重排产物。