An efficient carbonyl-alkene metathesis of bicyclic oxetanes: photoinduced electron transfer reduction of the Paternò-Büchi adducts from 2,3-dihydrofuran and aromatic aldehydes.

The bicyclic oxetanes and resulting from photocycloaddition of aromatic aldehydes to 2,3-dihydrofuran, were efficiently cleaved by means of electron-transfer reduction, photoinduced by the electronically excited reductants 1-methoxynaphthalene (MN) and 2,7-dimethoxynaphthalene (DMN) in acetonitrile. The fluorescence quenching rates of DMN/MN by and were determined by static methods, the triplet quenching rates were determined by means of laser flash photolysis (LFP). The product analysis established a "photo-photo metathesis" where both cycloaddition and cycloreversion processes are induced by photochemical processes.