Several benzyloxycarbonyl-a-amino acid phenylhydrazides were oxidized to give crystalline benzyloxycarbonyl-a-amino acid phenyldiimides. These compounds have an n 4 X* transition at 450 mp which causes a positive Cotton effect in their optical rotatory dispersion curves and a positive elipticity in their circular dichroism curves. The benzyloxycarbonylamino acid phenyldiimides reacted with amino acid phenylhydrazides ...