Computational investigation on the Mechanism of amide bond formation by using phosphine-based redox catalysis

A density functional theory investigation of the PPh3-catalyzed formation of amides from benzoic acid was explored. The results confirm the involvement of a phosphonium intermediate that is crucial to activate the carboxylate for nucleophilic acyl substitution. Going around in circles: The catalytic cycle of the phosphine-catalyzed Staudinger ligation of benzoic acid and benzyl azide involves several steps. All of them are explored at the density functional level. The results confirm the involvement of a phosphonium intermediate that is crucial to activate the carboxylate for nucleophilic acyl substitution.