Synthesis of potential agonists and antagonists for central glutamate receptors by a novel ‘ring switching’ process

Heterocyclic derivatives 6 of (S)-glutamic acid, which are structurally related to key central nervous system (CNS) glutamate receptor agonists, are prepared from the aldehyde 9 using a novel reaction in which the pyroglutamate ring is cleaved in concert with formation of the new heterocyclic ring.