Photocyclisation of benzyl cycloalk-1-enyl ketones

The benzyl cycloalk-1-enyl ketones (I)–(III) cyclise photochemically via singlet and triplet excited states to give the products (V)–(VII) in MeOH with and without CF3CO2H, in benzene with BF3-Et2O or CF3CO2H, and in MeCN with and without CF3CO2H.