Synthesis of novel 2-[2-(substituted amino)phenethyl]-1 H-benzimidazoles; 3,4-dihydro and 1,2,3,4,-tetrahydropyrimido[1,6-a]-benzimidazoles as potential antiulcer agents

In an effort to establish new antiulcer agents a series of 2-(2-substituted amino)-1 H-benzimidazoles 8, 9, 14; 1,3-disubstituted-3,4-dihydropyrimido[1,6-a]benzimidazoles 4, 7, 11, 12; 3-substituted-3,4-dihydropyrimido[1,6-a]benzimidazol-1 (2H)-thiones (or (2H)-ones) 10, 17 and 3-substituted-1,2,3,4-tetrahydropyrimido[1,6-a]benzimidazoles 15 were synthesized. Representative members were selected to evaluate their gastric antisecretory activity using an in vivo pylorus ligated rat method. Omeprazole was used as reference. The results indicated that the test compounds exhibit gastric antisecretory activity. The percent inhibition+/-SEM at the indicated dose level was demonstrated as omeprazole (59%+/-0.16 at 3 mg/kg) > 15a (53%+/-1.39 at 3 mg/kg) > 7a (51%+/-1.04 at 1 mg/kg) > 10a (50%+/-1.36 at 3 mg/kg).