An Efficient Light-Mediated Protocol for the Direct Amide Bond Formation via a Novel Carboxylic Acid Photoactivation Mode by Pyridine-CBr.

The direct amide bond formation between a carboxylic acid and an amine still constitutes a challenging reaction for both academia and industry. We demonstrate herein that several pairs of amines (halogen bond acceptors) and organohalogen sources may be used for the photochemical amidation reaction under either UVA or sunlight irradiation. Our studies led to the identification of pyridine-CBr as an efficient agent to perform amide synthesis under LED 370 nm irradiation, avoiding super-stoichiometric quantities.