Design, synthesis and preliminary evaluation of novel 3′-Substituted carboxycyclopropylglycines as antagonists at group 2 metabotropic glutamate receptors

Two novel 3′-substituted carboxycylopropylglycines, (2S,1′S,2′S,3′R)-2-(3′-xanthenylmethyl-2′-carboxycyclopropyl)glycine (8a) and (2S,1′S,2′S,3′R)-2-(3′-xanthenylethyl-2′-carboxycyclopropyl)glycine (8b), were synthesized and evaluated as mGluR ligands. Compound 8b showed to be a potent group II antagonist with submicromolar activity.