The condensation reaction between isocyanates and carboxylic acids. A practical synthesis of substituted amides and anilides.

Addition of a carboxylic acid to an isocyanate initially yields the mixed acid anhydride, decarboxylation of which leads to the N-substituted amide. The conversion of acid into amide was shown to proceed similarly for both aliphatic and aromatic carboxylic acids with a range of substituted isocyanates.