Preparation and use of chiral ferrocenylphosphines containing new alkyl substituents on the ferrocenylmethyl position

Article abstract of DOI:10.1016/0957-4166(95)00325-J

New homochiral ferrocenylphosphines, (Et-PPFA 5a), (Et-BPPFA 6a), and (Bu-BPPFA 6b), containing an ethyl or butyl group on the ferrocenylmethyl position were prepared by way of stereoselective ortho lithiation of (R)-N,N-dimethyl-1-ferrocenylpropylamine (4a) or its pentylamine analogue 4b, the lithiation proceeding with high (>99%) diastereoselectivity. Ethyl-substituted ferrocenylmonophosphine (Et-PPFA 5a) and ferrocenylbisphosphine (Et-BPPFA 6a) were found to be more effective as chiral ligands than the methyl-substituted ferrocenylphosphines, PPFA 1 and BPPFA 2, respectively, for some catalytic asymmetric reactions including nickel-catalyzed cross-coupling and palladium-catalyzed allylic silylation.