Photoaddition Reactions of 5‐Fluoro‐4,4‐dimethyl‐2‐cyclopentenone

Abstract

Abstract The photoaddition of 5‐fluoro‐4,4‐dimethyl‐2‐cyclopentenone ( 4 ) to 2,3‐dimethyl‐2‐butene leads specifically (in cyclohexane) and selectively (in acetonitrile) to the formation of the oxetanes 16 . The title compound is compared in its behaviour to the analogous 6‐fluoro‐4,4‐dimethyl‐2‐cyclohexenone ( 1 ) and both α'‐fluoro‐4,4‐dimethyl‐2‐cycloalkenones in turn are compared to the corresponding 2‐cycloalkenones ( 6 and 3 ) and 4,4‐dimethyl‐2‐cycloalkenones ( 5 and 2 ). The quantum yield for the addition of these enones to 2,3‐dimethyl‐2‐butene and to cyclopentene are discussed.