Synthesis of Bromophenyl β-D-Glucuronides: Hydrophilic Precursors of Lipophilic Standards in the Analysis of Environmental Polychlorinated Biphenyls

A rapid PCB-screening protocol, based on a combination of extraction techniques and instrumental nuclear activation analysis (INAA), required water soluble brominated internal standard that undergoes facile hydrolysis to a lipophilic brominated counterpart. Bromophenyl glucuronic acids 2, 3, 7 were synthesized for this application. Glucuronic acids 2 and 3 were prepared by bromination of phenyl β-D-glucopyranosiduronic acid in 81 and 54%, respectively, whereas compound 7 was prepared by coupling methyl 2,3,4-tri-O-acetyl-α-D-glucopyranosyluronate bromide (5) with 2,4,6-tribromophenol. Incubation with β-glucuronidase indicated that tribromophenyl derivative 7 is an excellent substrate, with near quantitative conversion to tribromophenol within seconds of incubation with the enzyme.