Mg/Fe-LDH: An efficient promoter for the synthesis of tetrahydrospiro[pyrazole-4,5′-pyrazolo[3,4-b]pyridine] derivatives

The synthesis of tetrahydrospiro[pyrazole-4,5′-pyrazolo[3,4-b]pyridine] derivatives using Mg/Fe-LDH as a heterogeneous catalyst was reported. This methodology used for the condensation of pyrazolones with aldehydes in a basic medium and with the presence of the Mg/Fe-LDH catalyst presents many benefits, such as the fact of using a reusable and low-cost catalyst, environmentally friendly conditions, short reaction times and excellent yields. It has been verified and confirmed that the catalyst is relatively stable and allows its reuse without additional treatment. Condensation has been carried out with different aldehydes and bis-pyrazolone derivatives have been obtained with yields ranging from 71 to 91% of purified product. The stereo impedance of the adduct formed prevents subsequent condensation.