Oxetane vs. cyclobutane formation in the photocycloaddition of enones to olefins. The photoaddition of 6-fluoro-4,4-dimethyl-2-cyclohexenone to 2,3-dimethyl-2-butene. Preliminary communication

n-π^* Excitation of 6-fluoro-4,4-dimethyl-2-cyclohexenone in the presence of 2,3-dimethyl-2-butene leads selectively to the formation of the corresponding oxetane. The factors which influence the oxetane vs. cyclobutane formation ratio in photoadditions of cyclic enones to olefins are discussed.