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
Photochemical Reactions. 125th communication [1]. Photochemistry of homoconjugated cyclobutanones. I. Synthesis and photolysis of a Spiro [3.6]deca-5, 7-dien-1-one
作者:Terry A. Lyle、Bruno Frei
DOI:10.1002/hlca.19810640816
日期:1981.12.16
The title compound 4 was prepared in 54% overall yield from eucarvone (5). On triplet sensitization 4 gives two products resulting from a 1,2-acyl shift (8 and 9), whereas singlet excitation of 4 causes decarbonylation and ketene elimination (4 10 and 11).