Synthesis of D-Glucopyranosyl Cholestan-3β-yl Glutamate Derivatives

Preferential formation of 1-(cholestan-3β-yl) N-CBZ-L-glutamate (3) or 5-(cholestan-3β-yl) N-CBZ-L-glutamate (4) was obtained when dicyclohexylamine or 4-(dimethylamino)pyridine was used as a basic catalyst for ester formation, respectively. Each glutamate was converted to an anomeric mixture of glucose derivatives : 1-(cholestan-3β-yl) 5-(2", 3", 4", 6"-tetra-O-benzyl-α- and -β-D-glucopyranosyl) N-CBZ-L-glutamates (7 and 8) or 5-(cholestan-3β-yl) 1-(2", 3", 4", 6"-tetra-O-benzyl-α- and -β-D-glucopyranosyl) N-CBZ-L-glutamates (9 and 10), using 2", 3", 4", 6"-tetra-O-benzyl-α-D-glucopyranose (11). After chromatographic separation of these isomers, their structures were determined by field desorption mass and nuclear magnetic resonance spectrometries.