SET and Exciplex Pathways in the Photochemical Reactions between Aromatic Ketones and Benzylsilane and Stannane Derivatives

The photochem. reaction of α,α,α-trifluoroacetophenone (TFA), benzophenone, and p-cyanoacetophenone with benzyltrimethylsilane in MeCN involves hydrogen transfer from the benzylic position. Desilylation occurs as a minor process only in the case of TFA (but it increases greatly in the presence of MeOH or LiClO4). The final products result from the statistical recombination of the benzyl and ketyl radicals.