Microwave assisted one-pot regioselective synthesis of 3,5-arylated pyrazoles from 2,3-dibromo-l,3-diarylpropan-l-ones using amberlite IR-120

摘要

An efficient and direct protocol for the preparation of 3,5-disubstituted pyrazoles, one-pot regioselective condensation reaction of 2,3-dibromo-1,3-diarylpropan-1 -ones with hydrazine derivatives via useful intermediate 4-bromo-1,3- aryl4,5-dihydro-lH-pyrazole in the presence of amberlite IR-120 under thermal and microwave conditions in EtOHas solvent is described. In this method, several types of aromatic diarylpropan, containing electron-withdrawing groups as well as electron-donating groups, were rapidly converted to the corresponding pyrazoles in good to excellent yields. The thermal solvent-free and microwave green procedures offer advantages such as shorter reaction times, simple work-up, excellent yield, recovery and reusability of catalyst.