Photochemical reactions of β-aminovinyl phenyl ketones and related compounds

Abstract

Photochemical reactions of some β-aminovinyl ketones and related compounds have been examined. Irradiation of the β-NN-dialkylaminovinyl phenyl ketones (1a–g) yielded the corresponding pyrroles (2a–g′), while ketones (1h–m) were inert. Irradiation of the (β-benzoylvinyl)trialkylammonium chlorides (7a and b) afforded the 1,4-diketones (8a and b) respectively. Irradiation of β-ethoxyvinyl phenyl ketone (5) gave an intractable mixture, while the corresponding thioketone (6) was photochemically inactive. Photolysis of the 2-dialkylaminobenzophenones (9a and b) gave the corresponding indoles (10a and b) respectively, accompanied by dealkylation products. The formation of the pyrrole was presumed to occur from the n–π* triplet state. The mechanisms of these photochemical reactions are discussed.