Novel oxa-di-π-methane and Norrish type I reactions in the S2 (π,π*) excited state of a series of β,γ-unsaturated ketones

beta,gamma-Unsaturated methyl ketones with electron-withdrawing groups at the gamma-position of the ene moiety undergo ODPM rearrangements and Norrish type I reactions on direct irradiation at 254 nm. The results are consistent with the involvement of alkene S-2 (pi,pi*) as reactive excited states in these processes.