Synthesis and reactions of polynuclear heterocycles with new ring systems

Condensation of 5,6-dimethyl-2-hydrazino-3,4-dihydrothieno[2,3-d]primidin-4-one (2) with aromatic aldehydes gave the arylhydrazones 3a-c which cyclized into thienotriazolopyrimidin-5- one 4a-c. Reactions of 2 with aliphatic acids afforded the thienotriazolopyrimidin-5-one 5a,b. Also, reaction of 2 with each of carbon disulfide and nitrous acid afforded 3-mercaptothienotriazolopyrimidin-5-one 7, and tetrazolothienopyrimidin-5-one 8, respectively, the latter compound 8could be reduced to 2-aminothienopyrimidin-4-one 9. On the other hand, 2-hydrazino derivative 2 condensed with alpha -haloketones yielded 3-substituted-thienopyrimidotriazin-6-one 10a,b with new ring system, and with beta -diketones, beta -ketoesters to form 2- (1-pyrazolyl) derivatives 13a-c, 14. The 2-pyrazolinone derivative 15 condensed with aromatic aldehydes to afford arylidene derivatives 16a-c. Also, reaction of 2 with ethyl cyanoacetate yielded 2-(pyrazolyl) derivatives 17.