Photolytic Release of Carboxylic Acids Using Linked Donor−Acceptor Molecules:  Direct versus Mediated Photoinduced Electron Transfer to N-Alkyl-4-picolinium Esters

Efficient photorelease (Φ = 0.7) of carboxylic acids is achieved with a covalently linked mediator (benzophenone) protecting group (N-alkyl-4-picolinium ester) molecule. The mechanism involves initial photoreduction of the mediator, followed by rapid electron transfer to the protecting group.