A mild synthesis of nitriles by von Braun degradation of amides using triphenyl phosphite–halogen-based reagents.

A mild procedure for the synthesis of aromatic and aliphatic nitriles is disclosed. In the presence of bromotriphenoxyphosphonium bromide (TPPBr2), N-alkyl and N,N-dialkyl amides undergo von Braun degradation to nitriles in good to excellent yields under the mildest conditions ever reported. The reaction proceeds via formation of an iminoyl bromide intermediate at –60 °C, which subsequently dealkylate upon refluxing in chloroform or even at r.t. In the case of N-tert-butyl, N-α-phenylethyl and N-benzhydryl amides, chlorotriphenoxyphosphonium chloride (TPPCl2) generated at –30 °C was also effective.