Studies on the Synthesis of New 3-(3,5-Diamino-1-substituted-pyrazol-4-yl)azo-thieno[2,3-b]pyridines and 3-(2-Amino-5,7-disubstituted-pyrazolo[1,5-a]pyrimidine-3-yl)azothieno[2,3-b]pyridines

Coupling the diazonium salt of 3-amino-2-cyano-4,6-dimethylthieno2,3-b]pyridine 1 with malononitrile 2 gave 2-cyano-3-(hydrazonomalononitrile)-4,6-dimethylthieno2,3-b]pyridine 3 which then reacted with hydrazine compounds 4a-4h to yield corresponding 2-cyano-3-(3,5-diamino-1-substituted-pyrazol-4-yl)azo-4,6-dimethylthieno2,3-b]pyridines 5a-5h. The 2-cyano-3-(2-amino-5,7-disubstituted-pyrazolo-1,5-a]pyrimidine-3-yl)azo-4,6-dimethylthieno2,3-b]pyridines 7a-7f were obtained in good yield by the cyclocondensation reaction of 2-cyano-3-(3,5-diamino-pyrazol-4-yl)azo-4,6-dimethylthieno2,3-b]pyridine 5a with the appropriate 1,3-diketones 6a-6f under acidic condition.