Phosphine‐Free Ruthenium(II) Catalysis Boosted by an NHC Ligand Effect in Acceptorless Dehydrogenative Amidation and Applications
Abhilash Viswanadhan, Karthikeyan Soundararajan, Sriram Rajagopal, Aneesh K. G., Manjunath Naik, Govindarajalu G, Ganesh Sambasivam, Karthik C. S.ABSTRACT
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.