Synthesis of Novel Fused Pyrimidines and Imidazoles as Potential Analgesics from 2-Amino-4-substituted-s- triazino[1,2-a]-benzimidazoles

The synthesis of novel fused pyrimidines and imidazole derivatives from 2-amino-s-triazino[1,2a]benzimidazoles 2a-e and 3a-c was successfully carried out by a ring annelation reaction in a very good yield. Compound 3c was screened for analgesic activity against acetic acid irritation and has shown protection equal to the reference drug (diclofenac sodium). The acute toxicity study revealed that compound 3c is safe up to 300 mg/kg and there is no sign and symptoms of toxicity and mortality for 72 hours.