Asymmetric hydrogenation catalyzed by aminophosphine-phosphiniterhodium complexes derived from natural aminoalcohols and x-ray crystal structure of (1,5-cyclooctadiene)-( S)- N-(diphenylphosphino)-2-diphenylphosphinoxymethylpyrrolidinerhodium(I) perchlorate

Abstract

From the cheap and readily available amino alcohols ( S)-pyrrolidinemethanol (( S)-prolinol), and ( S)-α- N-ethyl-aminobutanol, we have obtained two new aminophosphine-phosphinite ligands: ( S)- N-(diphenylphospino)-2-diphenylphos- phinooxymethylpyrrolidine (( S)-Prolophos) and ( S)-1-diphenylphosphinoxy-2- N-ethyl- N-diphenylphosphinoaminobutane (( S)-Butaphos). The rhodium(I) complexes of these phosphines act as efficient homogeneous hydrogenation catalysts at ambient temperature and pressures for dehydro N-acetyl amino acids, dehydro N-benzoyl amino acids and itaconic acid. An X-ray diffraction study of the complex [Rh(COD)(( S)-Prolophos)][ClO 4]· THF has been shown that the crystals belong to the monoclinic space group P2 1 with a 10.680(2), b 10.448(2), c 18.207(3) Å and β 104.97(1)ldg. Refinements based on 2105 significant counter reflections led to a final R value of 0.060. The cation is in a distorted square planar geometry, the rhodium atom being bound to the two phosphorus atoms and to the two double bonds of the diene molecule.