Journal of Molecular Catalysis A-Chemical, Vol.270, No.1-2, 127-131, 2007
Readily available phosphine-imine ligands from alpha-phenylethylamine for highly efficient Pd-catalyzed asymmetric allylic alkylation
A series of novel chiral phosphine-imine ligands have been prepared by a two-step transformation from chiral (x-phenylethylamine. The resulting chiral ligands were found to be effective for the palladium-catalyzed asymmetric allylic alkylation of 1,3-diphenylprop-2-en-1-yl pivalate with dimethyl malonate, in which up to 94% ee and 99% conversions were obtained. The results demonstrate that the chirality resided on the chelate ring of P-Pd-N complex is more effective for the transfer of the stereochemical information by comparison with the result obtained by Hashimoto and coworkers' phosphine-imine ligand, in which the chirality lay in the outside of P-Pd-N chelate ring. The effect of solvent, base and substitutent in phosphine-imine ligand on this catalytic reaction is also described. (C) 2007 Elsevier B.V. All rights reserved.