A series of 3-chloroquinoxaline-2-carboxamides were designed and prepared by the condensation of 3-chloro-2-quinoxaloylchloride with appropriate Mannich bases of the p-aminophenol in the microwave environment. The synthesized compounds were evaluated for serotonin 3 (5-HT 3 ) receptor antagonistic activities in longitudinal muscle-myenteric plexus (LMMP) preparation from guinea pig ileum against the 5-HT 3 agonist, 2-methyl-5-HT. Compound 3g exhibited comparable 5-HT 3 antagonistic activity (pA 2 6.4) to that of standard antagonist Ondansetron (pA 2 6.9), while the other compounds exhibited mild to moderate 5-HT 3 antagonistic activities.

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Fused pyridine derivatives R 0450 Microwave Assisted Synthesis of 2-(4-Substituted piperazin-1-yl)-1,8-naphthyridine-3-carbonitrile as a New Class of Serotonin 5-HT3 Receptor Antagonists. -Among the novel title naphthyridinecarbonitriles (VI) (12 examples) synthesized, derivative (VIf) shows the most favorable 5-HT3 receptor antagonism in Guinea pig ileum. -(MAHESH*, R.; PERUMAL, R. V.; PANDI, P. V.; Bioorg. Med. Chem.