SYNTHESIS OF SELECTIVELY C-13-LABELED BENZOIC-ACID FOR NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPIC MEASUREMENT OF GLYCINE CONJUGATION ACTIVITY

The synthesis of [4-C-13]benzoic acid (BA) labelled in a single protonated carbon, for use as a probe to measure glycine conjugation activity by nuclear magnetic resonance (NMR) spectroscopy, has been reported. The labelled compound was prepared by a seven-step synthetic scheme on a relatively small scale using [(2)-C-13]acetone as the source of label in overall yield of 16%. The usefulness of [4-C-13]BA was demonstrated by the NMR spectroscopic monitoring of urinary excretion of [4-C-13]hippuric acid in the rat administered with the labelled BA.