N-Carboxyphenylhydrazido derivatives of glycine, Dbalanine, Dbphenylalanine, Dkleucine, and DL-tyrosine have been prepared by refluxing carboalkoxyamino acid phenylhydrazides with potassium hydroxide in ethanol. The 5-substituted 3-anilinohydantoins were isolated as intermediates in the above reactions. The N-carboxyphenylhydrazidoamino acids were oxidized with potassium permanganate to give N-phenylazocarbonyl derivatives of the ...