Boric Acid Catalyzed Direct Amidation between Amino-Azaarenes and Carboxylic Acids

A novel and facile boric acid catalyzed direct amidation between amino-azaarene compounds and carboxylic acids has been developed. The amidation proceeded cleanly and provided good to excellent yields of the desired amides. Boric acid is a green and inexpensive catalyst. We have also found that N,N,N',N'-tetramethylpropane-1,3-diamine acted as an additive accelerating this boric acid catalyzed amidation. A mixed acid anhydride is postulated to be the active intermediate responsible for this successful amidation. This direct amidation is an atom- and step-economical reaction.