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

• Two series of imine and reduced imine compounds were formed and characterized.
• The formation of ruthenium complexes as in situ was investigated by UV–vis spectrophotometer.
• The catalytic activities of ligand/[(p-cymene)RuCl2]2 system were tested for TH of ketones.

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: 720 h−1 for 10 min on S/C: 500/1).

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