Photochemical reactions of acetylenic ketones

Abstract

The photochemical reactions of acetylenic ketones (1a and b) have been examined. Irradiation of 1-phenylprop-2-yn-1 -one (1a) in alcohols gave 2,5-disubstituted furans (2a–d) in 18–27% yield via cyclization of the intermediate; the C–C bonded 1 : 1 adduct of (1a) and the alcohol, while irradiation of (1a) and NN-diethylamine in benzene gave the pyrrole (7) in 61 % yield via cyclization of the intermediate, the C–N bonded 1 : 1 adduct of (1a) and the amine. Irradiation of 1,3-diphenylprop-2-yn-1-one (1b) and NN-dialkylamines afforded the C–C bonded 1 : 1 adducts (8a–c) in 30–40% yield.