With a view to obtain 5-bromo-1, 3-dimethyl-1H-pyrazole and 3-bromo-1, 5-dimethyl-1H- pyrazole we tried to perform bromination of 1, 3-dimethyl-1H-pyrazole-4-carbaldehyde (I) and 1, 5-dimethyl-1H-pyrazole-4-carbaldehyde (II) with subsequent oxidation and decarboxylation. Surprisingly, instead of the expected products III and IV, the bromination of formylpyrazoles I and II gave 4-bromo-1, 3-dimethyl-1H-pyrazole (V) and 4-bromo-1, 5- ...