Ultrasonics promoted synthesis of 5-(pyrazol-4-yl)-4,5-dihydropyrazoles derivatives

Abstract

A series of new 1,3-diaryl-5-(1-phenyl-3-methyl-5-chloropyrazol-4-yl)-4,5- dihydropyrazole derivatives have been synthesized under sonication conditions in ethanol or methanol/glacial acetic acid mixture (5/1 ratio) with two equivalents of hydrazines and seven kinds of chalcone-like heteroanalogues obtained from 5-chloro-3-methyl-1-phenyl- 1H-pyrazole-4-carbaldehyde. The structures were established on the basis of NMR, IR, MS and element analysis. This method provides several advantages over current reaction methodologies, including a simple work-up procedure, shorter reaction times (2-20 min) and good yields (65%-80%).