Reagent for protection of carboxylic acids as 4-methoxyphenacyl esters, which may be prepared in the presence of KF as base: Synthesis, 897 (1981) and can be cleaved photolytically: J. Org. Chem., 38, 3771 (1973). Peptide bonds are generally unaffected by irradiation but some cleavage of trityl protecting groups may occur. For further discussion of this and other photo-removable protecting groups, see: Synthesis, 1 (1980); Org. Photochem., 9, 225 (1987).