Journal of Molecular Catalysis A-Chemical, Vol.224, No.1-2, 71-79, 2004
New chiral N,P-oxazolines, and their Ir complexes in asymmetric hydrogenation of an imine
(+) (1S.2S)-2-Amino-1-phenyl-13-propanediol reacts with ortho-esters to form 4-hydroxymethyl-5-phenyl-1,3-oxazolines. Subsequent reaction of their toluenesulfonyl derivatives with diphenylphosphinolithium yields the N,P-ligands, (4S,5S)-2-R-4-diphenylphosphinomethyl-5-phenyl-1.3-oxazoline (R = Me, Et, Ph). X-ray analyses of (4S,5S)-2-methyl-4-toluenesulfonylmethyl-5-phenyl- 1,3-oxazoline and (4S,5S)-2,5-diphenyl-4-diphenylphosphinomethyl-1,3-oxazoline reveal retention of absolute configuration throughout the synthesis. The [Ir(COD)(N,P-oxazoline)]PF6 systems in CH2Cl2 effect catalytic hydrogenation of N-(1 -phenylethylidene)benzylamine, PhCH2N = C(Me)Ph, to the corresponding amine with upto 63% e.e. with the R = Et ligand. (C) 2004 Elsevier B.V. All rights reserved.