Nanoalkalinecellulose immobilized on magnetic nanoparticles as a green catalyst for the synthesis of tetrahydrodipyrazolopyridines and mechanistic insights under base catalysis

Abstract

The cotton-derived nanoalkalinecellulose (NAC) flocculated on the Fe 3 O 4nanoparticles was analytically characterized as Fe 3 O 4 @NAC. With the 1:5.7 weight ratio for organic:inorganic and the base-capacity equal to 7.5 mmol HO À /g, the Fe 3 O 4 @NAC represented a catalytic advantage in the roomtemperature one-pot pseudo-multicomponent synthesis of tetrahydrodipyrazolopyridines (THDPPs) in water. Mechanistic monitoring supported no requisite to acid/base catalyst in the first phase for rapid formation of intermediate 3-methylpyrazolone (A) by Knorr reaction of the ethylacetoacetate with hydrazine hydrate in water at room temperature. Alternatively, Fe 3 O 4 @NAC showed catalytic roles in the further reaction phases in synthesis of THDPPs from the A. Excellent base capacity, hydrogen-bonding performance, and stability due to no significant activity loss and leaching after five reaction cycles are advantages of this organometallic catalyst.

MgFe2O4@Tris magnetic nanoparticles: an effective and powerful catalyst for one-pot synthesis of pyrazolopyranopyrimidine and tetrahydrodipyrazolopyridine derivatives

“…The suggested mechanism for the production of tetrahydrodipyrazolopyridine using MgFe 2 O 4 @Tris MNPs as a catalyst is shown in Scheme 6 . 38 …”