Cationic and neutral ruthenium(II) complexes containing both arene or Cp* and functionalized aminophosphines. Application to hydrogenation of aromatic ketones

Hydrogen transfer reduction processes are attracting increasing interest from synthetic chemists in view of their operational simplicity. For this aim, a series of novel Ru(II) complexes with the P–N–P ligands were synthesized starting from the complex [Ru(η6-p-cymene)(μ-Cl)Cl]2 or [RuCp*Cl(COD)]. The complexes were fully characterized by analytical and spectroscopic methods. 31P–{1H} NMR, DEPT, 1H–13C HETCOR or 1H–1H COSY correlation experiments were used to confirm the spectral assignments. Complexes 5, 6 and 7 catalyze the transfer hydrogenation of acetophenone derivatives to 1-phenylethanol derivatives in the presence of iso-PrOH as the hydrogen source. Catalytic studies showed that all complexes are excellent catalytic precursors for the transfer hydrogenation of acetophenone derivatives in 0.1 M iso-PrOH solution. Notably 5 acts as an excellent catalyst giving the corresponding alcohols in excellent conversions up to 99% (TOF ≤ 492 h−1).

The synthesis and characterizations of three novel bis(phosphino)amine complexes derived from [H2N–C6H4-2-CH(CH3)2] or [H2N–C6H4-4-CH(CH3)2] are described. Transfer hydrogenation of acetophenone derivatives catalyzed by these complexes is also investigated. Catalytic studies showed that all complexes are superior catalytic precursors for the transfer hydrogenation of acetophenone derivatives in 0.1 M iso-PrOH solution. Notably [Ru((Ph2P)2N–C6H4-2-CH(CH3)2)(η6-p-cymene)Cl]Cl acts as an excellent catalyst giving the corresponding alcohols in excellent conversions up to 99% (TOF ≤ 492 h−1).Figure optionsDownload as PowerPoint slide