Easily Accessible Chiral P,N-Bidentate Aryl Phosphites, Their Complexation and Application in Enantioselective Allylic Alkylation, Sulfonylation and Hydrosilylation

Abstract

New chiral P,N-hybrid aryl phosphites have been obtained by one-step phosphorylation of amino and imino alcohols. Complexation of the new ligands with [Rh(CO) 2 Cl] 2 , [Pd(COD)Cl 2 ] and [Pd(allyl)Cl] 2 was found to give chelate complexes [Rh(CO)Cl(η 2 -P ʝ N)], [PdCl 2 (η 2 -P ʝ N)] and [Pd-(allyl)(η 2 -P ʝ N)] + Cl − , respectively. With these new P,N-ligands, up to 82% ee enantioselectivity was achieved in the [a] The new P,N-bidentate aryl phosphites were synthesized by one-step phosphorylation of the corresponding amino and imino alcohols with bis(2,6-dimethylphenyl) chlorophosphite.They divide into two groups: ligands 3aϪ3f, possessing sp 3 -hybridized nitrogen atoms, and ligands 3gϪ3m, which have sp 2 -hybridized nitrogen atoms. All the compounds 3aϪm are soluble in conventional organic solvents and stable under dry conditions for several months. On treatment with [Rh(CO) 2 Cl] 2 , their neutral carbonyl(chloro)Rh I complexes were obtained.The ν(CO) and 1 J P,Rh parameters in their IR and 31 P NMR spectra act as sensitive indicators, which characterise the mode of complexation of the P,N-ligands and allow the π-acceptor ability of the phosphorus centre and the degree of electronic non-symmetry of the ligands to be estimated. [13Ϫ15] In general, ligands 3aϪ3m give chelate complexes. Thus, the