Reactions With Ethyl-4,5,6,7-Tetrahydro-2-Isothiocyanato-1-Benzothiophene-3-Carboxylate. Synthesis of Some Novel Heterocyclic Compounds With Potential Hypnotic Activity

Ethyl-4,5,6,7-tetrahydro-2-isothiocyanato-1-benzothiophene-3-carboxylate (2), prepared from ethyl-4,5,6,7-tetrahydro-2-amino-1-benzothiophene-3-carboxylate (1) by the thiophosgene method, was converted with nucleophiles into benzothieno[2,3-d]pyrimidine derivatives (3–5) and (7) either directly or through thiourethane (6a). The tricyclic, benzothienopyrimidine systems (8) and (9) were obtained either from the isothiocyanate (2) or the thiourethane (6a), while the tetracyclic systems, triazolothienopyrimidines (10,11); tetrazolothienopyrimidines (12,13) and tetrazepino derivative (14), were obtained from 2,3,5,6,7,8-hexahydro-3-amino-2-hydrazino-1-benzothieno[2,3-d]pyrimidine-4(3H)-one (9). Preliminary pharmacological screening revealed that some of the new compounds exhibited hypnotic activity.