4-Nitrophenyl N-substituted carbamate is known as a pre- cursor of isocyanate1 and is utilized in the synthesis of multi- substituted urea.2 On the other hand, isocyanate reacts with some nucleophiles such as carboxamide3 and carboxylic acid4 to afford N-acylurea or carboxamide, respectively. From the above reports, we assumed that treatment of N-(4-nitrophen- oxycarbonyl)amino acid (Npoc-AA-OH) with amine generated 2-isocyanatocarboxylic ...