Design, Synthesis Of Novel Phosphorus-Containing Ligands And Their Application In The Catalytic Enantioselective Hydrogenation

With this context, three kinds of chiral monodentate phosphoramidite ligands, two kinds of chiral monodentate phosphites and two kinds of bidentate phosphorus ligands have been explored. By use of chiral 1-ferrocenylethylamine, 1-phenylethylamine, L-prolinol ether, 1-ferrocenylethanol and BINOL-derived monoether as the starting materials respectively, a series of BINOL-based monodentate phosphoramidite and phosphite ligands were prepared in a similar procedure. By combination of axial-chiral H8-BINOL with chiral 1-[2-(diphenyl- phosphino)ferrocenyl]ethylamine, a new family of unsymmetrical hybrid phosphine-phosphoramidite ligands were synthesized. C2-symmetrical bidentate phosphoramidite ligands were prepared by the reaction of N,N'-dimethyl-1,2-diphenylethylenediamine and chiral BINOL.The efficiency of these phosphorus ligands in the Rh-catalyzed asymmetric hydrogenations of functionalized olefins was investigated, and the results indicated: 1) Among ligands F-1~F-4, F-1a exhibited the best results in the hydrogenations ofα-dehydroamino acid esters, enamides, dimethyl itaconate andβ-dehydroamino acid esters, giving the hydrogenation products in 99.5% ee, 99.5% ee, 96.1% ee and 99.3% ee respectively. 2) B-5a/Rh complex was highly effective for the hydrogenation ofα-dehydroamino acid esters, enamides and dimethyl itaconate, providing the hydrogenation product in 99.5% ee, 97.5% ee and 94% ee respectively. 3) P-6a/Rh complex showed 90.4% ee and 87.5% ee in the hydrogenation ofα-dehydroamino acid esters and dimethyl itaconate, respectively. 4) Bidentate phosphorus ligands F-12 exhibited 99.9% ee, 97.5% eeand 99.9% ee in the hydrogenation ofα-dehydroamino acid esters, enamides and dimethyl itaconate. 5) Ligands B-11 only displayed moderate to low enantioselectivity.