Synthesis and configurational assignment of 1,2-dihydroimidazo[5,1-b]quinazoline-3,9-diones: novel NMDA receptor antagonists

NMDA receptors form a major subdivision of the ionotropic glutamate receptor family that mediates excitatory synaptic transmission in the brain. Series of 1-substituted 1,2-dihydroimidazo[5,1-b]quinazolinediones were synthesized and found to have potent nanomolar activity at the glycine site of the NMDA receptor. Imidazoquinazolinediones were prepared by cyclocondensation of 4-oxo-quinazoline-2-carboxamide with aldehydes and orthoesters with good yields. The formed enantiomers were separated by chiral HPLC. The absolute configuration of pure enantiomers is elucidated by combined CD/Quantumchemical time-dependent DFT calculation method (TDDFT).