Synthesis and biological activity of cyclic analogues of MPPG and MCPG as metabotropic glutamate receptor antagonists

The synthesis of two rigidified phenylglycine analogues is disclosed. The cyclic analogue 1 of (R,S)-α-methyl-4-phosphonophenylglycine (MPPG) is shown to be a particularly interesting pharmacological tool, for it is a group II selective mGluR antagonist that possesses an inverse agonist-like-action.