Ketone transfer hydrogenation reactions catalyzed by catalysts based on a phosphinite ligand

Abstract

Reaction of (±)-1-(2-furyl) ethanol with an equivalent Ph2PCl in the presence of Et3N proceeds in dry toluene under an argon atmosphere to give 1-(furan-2-yl)ethyl diphenylphosphinite (1) in good yield. Mononuclear complexes [dichloro(η6-p-cymene)(1-furan-2-ylethyl diphenylphosphinite)ruthenium(II)] (2), [dichloro(η6-benzene)(1-furan-2-ylethyl diphenylphosphinite)ruthenium(II)] (3), [chloro(η4-1,5-cyclooctadiene)(1-furan-2-ylethyl diphenylphosphinite)rhodium(I)] (4) and [dichloro(η5-pentamethylcyclopentadienyl)(1-furan-2-ylethyl diphenylphosphinite)iridium(III)] (5) were synthesized and characterized by microanalysis, infrared, MS, and NMR spectroscopies. The complexes are employed as catalysts in transfer hydrogenation of aromatic ketones. The complexes catalyzed reduction of a variety of aromatic ketone substrates bearing electron-withdrawing or donating substituents with very high conversion rates (up to 99%); 5 was the most efficient catalyst for the transfer hydrogenation of ketones.