o-Nitrophenylethylene glycol as photoremovable protective group for aldehydes and ketones: syntheses, scope, and limitations

Abstract

The preparation of o-nitrophenylethylene glycol is described along with its application as a photolabile protective group for aldehydes and ketones. Formation of the acetals and ketals is achieved in good to high yields in the usual manner and deprotection is carried out in fair to high yield, by photolysis at 350 nm in an inert solvent such as benzene. Because of the particular nature of the present protective group, its stability to basic and acidic conditions has been examined and is reported to complete the scope and limitations aspect. From a mechanistic point of view, the isolation and characterization of o-nitroso-α-hydroxyacetophenone as the spent reagent demonstrates a mechanistic link with the known o-nitrobenzaldehyde to o-nitrosobenzoic acid photorearrangement.