This study was aimed at the synthesis of fused benzothiophene derivatives containing heterocyclic moiety. The reaction of the tetrahydrobenzo[b]thiophene derivatives 1a,b with ethoxycarbonylisothiocyanate afforded the thiourea derivatives 2a,b. Cyclization of the latter products gave the annulated benzo[b]thienopyrimidine derivatives 3a,b. Compounds 2a,b and 3a underwent a series of heterocyclization reactions through the reaction with some chemical reagents to give the new benzo[b]thienopyrimidine derivatives 5a,b to 8a-c. Also, this work was extended to study the potential role of the novel synthesized thiourea derivative 2a and benzo[b]thienopyrimidine derivatives 3a, 5b, 6a and 8b as antidepressant, sedative or analgesic agents at two doses (15 or 30 mg kg-1 body mass). Some compounds (2a, 3a and 5b) showed mild antidepressant activity in the forced-swimming test. No compound showed sedative effect. Visceral pain evoked by i.p. injection of acetic acid in mice was significantly inhibited by all compounds at a high doses.
