Synthesis of new 2-[(substituted-pyrazolin-1-yl)carbonyl]-thieno[2,3-b]pyridine derivatives

The reaction of 3-amino-4,6-dimethyl-2-thieno[2,3-b]pyridine carbohydrazide (1) with appropriate chalcones 2a-2d in the presence of acid catalyst prod uced the corresponding 3-amino-2-[(3,5 -disubstituted-pyrazolin-1-yl)carbon yl]-4,6-dimethylthieno[2,3-b]pyridines 3a-3d. 3-Amino-2-[(3-substituted-pyr azolin-1-yl)carbonyl]-4,6-dimethylthieno[2,3-b]pyridines 7a, 7b were also o btained by the cyclization reaction of carbohydrazide 1 with Mannich base d erivatives 6a, 6b under basic condition.