Photoinduced reactions—XLVIII : Steric and substituent effects on photoreactions of 2,4,6-trialkylphenyl ketones

Abstract

Steric and substituent effects on the photochemical reaction of 2,4,6-trialkylphenyl ketones has been investigated. A striking steric effect was observed in the photoreaction of 2,4,6-trialkylbenzophenones. The more hindered the carbonyl group, the more readily photoenolization occurs resulting in intramolecular cyclization leading to benzocyclobutenol derivatives. With 2,4,6-trialkylacetophenones. such a steric effect was not observed in the cyclization and photoenolization reactions. These reactions have been interpreted in terms of the excited state nature responsible for these reactions.