Photochemical C-H acetalization of O-heterocycles utilizing phenylglyoxylic acid as the photoinitiator.

A novel, mild, metal-free and easy-to-execute procedure for the C–H acetalization of O-heterocycles via visible light activation is presented, utilizing phenylglyoxylic acid as the photoinitiator. Biomass-derived O-heterocycles, like THF, can be employed, while primary, secondary alcohols and alcohols bearing a variety of functionalities were succesfully employed, affording the desired acetals in high yields. Facile acidic deprotection was also performed.