Synthesis of novel 5,6,7,8-tetrahydro-4H-thieno[2,3-b][1,4]-diazepine derivatives

Unsubstituted 5,6,7,8-tetrahydro-4H-thieno[2,3-b][1,4]diazepine (1) and 4H-thieno[2,3-b][1,4]diazepine-5,7(6H,8H)-dione (2) were newly synthesized. Benzoylation of 1 regioselectively afforded thienodiazepine (13) substituted with a benzoyl group at position 4. Alternatively, novel synthetic procedures were devised to yield thienodiazepine (22) substituted with an alkyl group or compound (14) with an aralkyl group at position 8. Thus, the ingenious introduction of functional groups at the N-4 or 8 position of a thienodiazepine skeleton was achieved and then a variety of 5,6,7,8-tetrahydro-4H-thieno[2,3-b][1,4]diazepines (5)-(9), and (27), some of which exhibited potent arginine vasopressin antagonistic activity, were obtained using the key intermediates (1), (13), (14), and (22).