Chiral bidentate aminophosphine ligands: synthesis, coordination chemistry and asymmetric catalysis

Chiral aminophosphines Ph2PN( R) ( CH2) (n) N( R)PPh2 1 - 4 [ n = 2, R = CH( CH3) ( Ph) 1; n = 3, R = CH( CH2CH3) ( Ph) 2, n = 2, R = CH( CH3) ( 1- naphthyl) 3; n = 2, R = CH( CH3) ( C6H11) 4] were synthesized by the reaction of ClPPh2 with the appropriate easily accessible enantiopure amine building blocks. For compounds 1 and 2, the corresponding selenides 5 and 6 were prepared to determine the electronic character of the phosphine moieties. By reaction of 1 with either PdCl2( cod) or PdCl( CH3) ( cod) the cis - complexes 7 and 8 were obtained. The molecular structure for complex 7, cis - [ PdCl2( 1)], was determined by X- ray crystallography. Reaction of PtCl2( cod) with 1 or 2 yielded the corresponding monomeric cis - isomers 9 and 10. The rhodium derivative [ RhCl( CO) ( 1)] ( 11) was obtained as a mixture of cis and trans - isomers. Preliminary results in the rhodium catalyzed hydroformylation of styrene and vinyl acetate, with ee s up to 51% and high regioselectivities, showed the potential of these chiral aminophosphines for homogeneous catalysis.