Enantioselective addition of diethylzinc to a N-diphenylphosphinoylimine employing cinchona alkaloids as chiral ligands

The use of cinchona alkaloids to promote the addition of diethylzinc to P,P-diphenyl-N-(phenylmethylene)phosphinic amide has been examined. Using cinchonine and cinchonidine as ligands, the S and R enantiomers of N-(1-phenylpropyl)-P,P-diphenylphosphinic amide were prepared in good yield with up to 93% ee. The reaction was shown to proceed with catalytic amounts of ligand.