Benzil I was found to add photochemically to ethyl vinyl ether III, a-
methylstyrene IV, furan V and 2,3-dimethyl-2-butene VI to give the cor
responding oxetanes as the major photoproducts, (in the case of 2,3-di
methyl-2-butene, dioxene was also formed in equal amounts), whereas wi
th furfural II, the photoproduct was found to be the corresponding ket
o ester.