Enantioselective catalysis. 157 [1] carbohydrate-based, water-soluble ligands for the stereoselective hydrogenation of folic acid

Abstract

The new chiral ligands 11-30 were synthesized by combining aldehydes and ketones, able for coordination, with mono-and disaccharides via oxime ether bridges stable towards hydrolysis. Due to their OH groups they were water-soluble (except 11 and 19), whereas their acetylated analogs dissolved in organic solvents. The new ligands were used in homogeneous and heterogenized catalysts for the stereoselective hydrogenation of folic acid 31, the formylated hydrogenation product 33 of which is the anticancer drug Leucovorine. © 2005 Wiley-VCH Verlag GmbH & Co. KGaA.