The synthesis of the 1-benzyl derivative of (2R, 4R)-4-aminopyrrolidine-2, 4-dicarboxylic acid (1-benzyl-APDC) starting from cis-4-hydroxy-D-proline is disclosed together with a study of the activity of this compound at metabotropic glutamate receptors (mGluRs). The compound was found to display good mGluR6 selectivity, and may thus be a useful pharmacological research tool.