Discovery and structure-activity relationships of 4-aminoquinazoline derivatives, a novel class of opioid receptor like-1 (ORL1) antagonists

Synthesis and structure-activity relationship studies of a series of 4-aminoquinazoline derivatives led to the identification of (1R, 2S)-17, N-[(1R, 2S)-2-({2-[(4-chlorophenyl) carbonyl] amino-6-methylquinazolin-4-yl} amino) cyclohexyl] guanidine dihydrochloride, as a highly potent ORL1 antagonist with up to 3000-fold selectivity over the mu, delta, and kappa opioid receptors. Molecular modeling clarified the structural factors contributing to the high affinity and selectivity of (1R, 2S)-17. (c) 2008 Elsevier Ltd. All rights reserved.