The synthesis of some 7-phenylhydrazides of N-carbobenzoxy-eL-glutamylamino acid esters (111) is described. Treatment of aqueous acetic acid solutions of these compounds n- ith manganese dioxide, at room temperature, results in the rapid oxidation of the phenylhydrazide group to a carboxylic acid leaving the carbobenzoxy group and the ester intact and without racemization. The use of the phenylhydrazide group as a protective ...
