A new photolabile protecting group for release of carboxylic acids by visible-light-induced direct and mediated electron transfer.

A new aqueous-compatible photoinduced electron transfer based photolabile protecting group has been developed for the release of carboxylic acids. The reduction potential of this group is more positive than previous systems, thereby allowing the use of sensitizers with modest oxidation potentials. Release of several carboxylic acids has been demonstrated using tris(bipyridyl)ruthenium(II) as both a direct sensitizer and a mediator for electron transfer between a good donor and the protecting group.