Synthesis of imine and reduced imine compounds containing aromatic sulfonamide: Use as catalyst for in situ generation of ruthenium catalysts in transfer hydrogenation of acetophenone derivatives

Abstract

Three imine and three reduced imine ligands containing aromatic sulfonamide (2–7) were isolated by a simple method and characterized by FT-IR, NMR, and elemental analysis. Meanwhile, the interaction of 2–7 ligands with [(p-cymene)RuCl2]2 was analyzed in situ by UV–vis spectrophotometer. The in situ generated catalytic system derived from N-(2-(benzylideneamino)phenyl)-2,4,6-trimethyl-benzenesulfonamides and N-(2-(benzylamino)phenyl)-2,4,6-trimethyl-benzenesulfonamides with [(p-cymene)RuCl2]2 was used as a catalyst in the transfer hydrogenation (TH) of p-substituted acetophenone derivatives. The catalytic systems displayed high activities, which increased in the order 7<4<5<6<1<2<3. The best activity for the TH of 4-chloroacetophenone was provided with the [(p-cymene)RuCl2]2/ligand (3) catalytic system (turnover frequency values: 720h−1 for 10min on S/C: 500/1).