6-(Pyrazol-1-yl)pyrazolo[3,4-b]pyridines: Synthesis, Structure, and Wheat Growth Regulating Activity

4-Methyl-6-pyrazolyl-2-chloronicotinonitriles were synthesized by the reaction of 6-hydrazino-4-methyl-2-chloronicotinonitriles with 1,3-diketones. Upon treatment with hydrazine and methylhydrazine, 4-methyl-6-pyrazolyl-2-chloronicotinonitriles were converted into the corresponding 3-amino-4-methyl-6-pyrazolyl-1H-pyrazolo[3,4-b]pyridines. A similar reaction involving 1,1-dimethylhydrazine and ethylhydrazine was accompanied by elimination of the alkyl substituent and also led to the formation of 3-amino-6-pyrazolyl-1H-pyrazolo[3,4-b]pyridines. Acylation and carbamoylation of the prepared compounds proceeded regioselectively at the amino group. One of the new compounds, N-[6-(3,5-dimethylpyrazol-1-yl)-1,4-dimethyl-1H-pyrazolo[3,4-b]pyridin-3-yl]cyclopropanoylamide, showed a growth-stimulating effect in the field experiments on winter wheat crops.