A New Class of Bidentate Nitrogen Ligands for Suzuki–Miyaura Cross-Coupling of Aryl Iodides and Bromides in Green Solvents

Inexpensive nitrogen-based bidentate pyridinium amidate ligands with simple Pd(II) salts generate in situ Pd(0) catalysts that efficiently promote Suzuki–Miyaura cross-coupling of aryl iodides and bromides. Operating at very low palladium loadings (0.1–0.005 mol%) with TONs up to 17800, the reactions give high yields (51–96%) using K2CO3 in a green hydroxyethyl pyrrolidone/water (6:4) solvent mixture. The protocol minimizes metal residues, allows >90% palladium recovery and reduces PMI from 30 to 8. DFT studies indicate transmetalation as the rate-determining step.