Phosphine‐Free Ruthenium(II) Catalysis Boosted by an NHC Ligand Effect in Acceptorless Dehydrogenative Amidation and Applications

We report a practical, atom‐economical protocol for the synthesis of amide derivatives via acceptorless dehydrogenative coupling of alcohols and amines, which employs a thiophene‐based phosphine‐free Ru(II) complex (ARP‐03) along with an N ‐heterocyclic carbene (NHC) precursor as an additive. Under optimized conditions (2.0 mol% ARP‐03, 0.5 mol% NHC‐01, 30 mol% KOH, toluene, 80°C), a broad set of benzylic alcohols and amines affords the corresponding primary and secondary amides in moderate to good isolated yields with high functional‐group tolerance and concomitant H 2 evolution. Control experiments support the amide formation with the release of H 2 molecules and hemiaminal formation. The utility of the developed method is demonstrated through the synthesis of pharmaceutically and industrially relevant amides such as trimethobenzamide and DEET.