engleski

Chiral bidentate ligands from the most widespread monosaccharides for enantioselective hydrogenation: diphenylphosphinites from D-glucose and D-xylose

(2R, 3S)-2-Diphenylphosphinoxymethyl-3-diphenylphosphinoxytetra-hydropyran (2) and (3R, 4R)-3, 4-bis-diphenylphosphinoxytetrahydropyran (4) were prepared from D-glucose and D-xylose, respectively, and characterized as their Cu(I) complex salts (5 and 6). Rh(I) NBD (NBD = norborna-diene) complexes of 2 and 4 were used for the enantioselective hydrogenation of Z-α -acetylaminocinnamic acid. The complex of 2 afforded R-, while the complex of 4 afforded S-α -acetylaminophenylalanine, the enantiomeric excess (e.e.) being dependent on temperature. The highest e.e. (90.4%) was obtained with the Rh(I) complex of 4 at -15 °C.

Chiral bidentate ligands ; diphenylphosphinites ; monosaccharides

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