Tandem Synthesis of 2,3,4,5-Tetrasubstituted Pyrroles from Aromatic Aldehydes Using Diethylene Glycol-bis(3-methylimidazolium) Dihydroxide as an Efficient Catalyst

A sequential process strategy was introduced for the synthesis of 2,3,4,5-tetrasubstituted pyrroles by the formation of benzoin from the corresponding aromatic aldehyde and followed by condensation reaction with 1,3-dicarbonyl compounds and ammonium acetate in the presence of diethylene glycol-bis(3-methylimidazolium) dihydroxide as catalyst in refluxing ethanol. The recycled catalyst could be reused four times without appreciable loss in the catalytic activity.