Chemical modification of aryl-1,2,3,6-tetrahydropyridinopyrimidine derivative to discover corticotropin-releasing factor1 receptor antagonists: Aryl-1,2,3,6-tetrahydropyridino-purine, -3H-1,2,3-triazolo[4,5-d]pyrimidine, -purin-8-one, and -7H-pyrrolo[2,3-

Structure–affinity relationships (SARs) of non-peptide CRF1 antagonists suggest that such antagonists can be constructed of three units: a hydrophobic unit (Up-Area), a proton accepting unit (Central-Area), and an aromatic unit (Down-Area). Recently, various non-peptide corticotropin-releasing factor1 (CRF1) receptor antagonists obtained by modification of the Central-Area have been reported. In contrast, we modified the Up-Area and presented 4- or 5-aryl-1,2,3,6-tetrahydropyridinopyrimidine derivatives including potent CRF receptor ligands 1a–c, and proposed that the 4- or 5-aryl-1,2,3,6-tetrahydropyridino moiety might be useful as a substituent in the Up-Area. Our interest shifted to the chemical modification in which the pyrimidine ring of 1a–c was replaced by other heterocycles, purine ring of 2, 3H-1,2,3-triazolo[4,5-d]pyrimidine ring of 3, purin-8-one ring of 4 and 7H-pyrrolo[2,3-d]pyrimidine ring of 5. Among them, 5-aryl-1,2,3,6-tetrahydropyridinopurine compound 6j (CRA0186) had the highest affinity for CRF1 receptors (IC50=20 nM). We report here the synthesis and SARs of derivatives 6–9.