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

Abstract

The synthesis of tetrahydrospiro[pyrazole-4,5'-pyrazolo[3,4-b]pyridine] derivativesusing Mg/Fe-LDH as a heterogeneous catalyst was reported. This methodology usedfor the condensation of pyrazolones with aldehydes in a basic medium and with thepresence of the Mg/Al-LDH catalyst presents many benefits, such as the fact of using areusable and low-cost catalyst, environmentally friendly conditions, time short reactiontimes and excellent yields. It has been verified and confirmed that the catalyst isrelatively stable and allows its reuse without additional treatment. Condensation hasbeen carried out with different aldehydes and bis-pyrazolone derivatives have beenobtained with yields ranging from 71 to 91% of purified product. The stereo impedanceof the adduct formed prevents subsequent condensation.