Synthesis of Bile Acid 24-acyl Glucuronides

Abstract

The synthesis of acyl glucuronides of common bile acids is described. By means of the Mitsunobu reaction employing diethylazodicarboxylate and triphenylphosphine, bile acids were condensed through the inherent C-24 carboxy group with benzyl 2,3,4-tri- O-benzyl- d-glucopyranuronate, which was prepared from 1- O-methyl-α- d-glucose. The separation and purification of the β-anomers at the anomeric position of the sugar moiety were attained by preparative thin-layer chromatography and/or high-performance liquid chromatography on a column packed with phenyl-bonded silica using H 2O-MeOH as a mobile phase. The removal of the benzyl group on the sugar moiety was achieved by catalytic hydrogenation with 10% palladium on carbon to yield the desired acyl glucuronides of bile acids. The structures of these acyl glucuronides were confirmed by proton nuclear magnetic resonance spectral properties.