Catalyst-free grinding method: a new avenue for synthesis of 6-amino-3-methyl-4-aryl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile and DFT studies on the mechanistic pathway of this category of compounds

A novel, efficient, one-pot, catalyst-free grinding procedure for synthesis of 6-amino-3-methyl-4-aryl-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile is reported. The condensation of substitutedbenzaldehydes, 3-amino-5-methylpyrazole, and malononitrile according to a three-component reaction was investigated using density functional theory (DFT) at B3LYP/6-311G level to explore the reaction mechanism. All the routes were studied, the structure of the intermediates was optimized, and all the respective transition states were found. The results of the calculations show that the proposed mechanism relies on four intermediates.