Photochemical Reactions of Mercapto/Amino Substituted Alkyl Phenylglyoxylates Induced by Intramolecular Electron Transfer

Article abstract of DOI:10.1016/S0040-4020(97)00044-6

2'-Alyothio ethyl phenylglyoxylates (1) and 2'-dimethylamino ethyl phenylglyoxylate (10) were synthesized and their photochemistry studied.In contrast to their oxygen analog 3, which give normal Norrish type II cleavage products, the title compounds undergo intermolecular electron transfer from the heteroatom (sulfur/nitrogen) to the excited carbonyl group, followed by proton transfer and subsequent closing of the resulting biradical to produce seven-mebered (11) lactones in high yield.Thiadialkyl phenylglyoxylates (9) react inefficiently due to intramolecular self-quenching of phenylgluoxylate chromophores.The photoreactivity of α-oxothioester (14) was compared with that of its nitrogen (α-oxoamide) and oxygen (phenylglyoxylate) counterparts. - Keywords: Photochemical; Mercapto; Amino; Phenylglyoxylates; Electron Transfer