Photo-induced reduction of pyridinium ions catalysed by zinc(II) tetraphenylporphyrin

Abstract

Photo-induced (>460 nm) Zn^II tetraphenylporphyrin-catalysed reduction of 1,2,6-trimethyl-3,5-bisethoxy-carbonylpyridinium perchlorate (1a) and 1-methyl-3-carbamoylpyridinium perchlorate (1b) has been studied. 1,2,6-Trimethyl-1,2-dihydro-3,5-bisethoxycarbonylpyridine (2a), a reduction product, was formed by irradiation of (1a) in an aqueous mixture of ascorbic acid, sodium laurylbenzenesulphonate, polyoxyethylene octylphenyl ether, and Zn^II tetraphenylporphyrin, whereas a corresponding 1,2-dihydropyridine (2b) was not obtained from 1-methyl-3-carbamoylpyridinium perchlorate (1b) under similar conditions.