Organic Photochemical Reactions. XXXI. Photosensitized Ring-Cleavage Reactions of 2,2-Diaryloxetanes by Aromatic Nitriles

Article abstract of DOI:10.1246/bcsj.62.96

Photosensitized reactions of 2,2-diaryloxetanes by 1,4-dicyanonaphthalene, 1-cyanonaphthalene, and 9,10-dicyanoanthracene, which give such ring-cleavage products as substituted benzophenones and alkenes, have been investigated.Quantum yields for the ring cleavage vary with the substituents on both the aryl group and oxetane ring.The quantum yield increases with increase in electron-donating ability of the oxetane.The limiting quantum yields in the case of 1,4-dicyanonaphthalene-photosensitized reaction of 2,2-di-p-tolyl- or 2,2-bis(p-methoxyphenyl)-3,3,4-trimethyloxetane exceed unity.The mechanism is discussed in terms of electron transfer from oxetanes to the excited singlet state of the sensitizer as well as the regeneration process of the oxetane cation radical involving the hole transfer from substituted benzophenone cation radicals to oxetanes in the chain process.