Efficient Synthesis and Gastric (H+/K+)-ATPase-Inhibitory Activity of 2-Aryl-4, 5-dihydro-1H-thieno[3, 2-e]benzimidazoles

A series of 2-aryl-4, 5-dihydro-1H-thieno[3, 2-e]benzimidazoles (1, 2) was prepared by condensation of 5-acylamino-4, 5, 6, 7-tetrahydrobenzo[b]thiophen-4-ones (9, 10) with ammonium acetate under azeotropic reaction conditions. Various congeners, N-methyl and N-phenyl analogues (3-5), 4, 5-dihydro-1H-thieno[2, 3-e]benzimidazoles (6), 4, 5-dihydro-1H-thieno[2, 3-g]benzoxazoles (7), and 4, 5-dihydro-1H-thieno[2, 3-g]benzothiazoles (8), were also prepared. Several compounds in this series were shown to be K+-competitive inhibitors of the gastric (H+/K+)-ATPase and more potent inhibitors than SK&F-96067, 3-butyryl-8-methoxy-4-(2-tolylamino)quinoline, on pentagastrin-stimulated acid secretion in chronic gastric fistula rats after intraduodenal administration.