Deep eutectic solvent: a simple, environmentally benign reaction media for regioselective synthesis of 2,3,4-trisubstituted 1H-pyrroles

Abstract

Choline hydroxide has been successfully employed as an efficient base as well as reaction media for the synthesis of 2,3,4-trisubstituted 1H-pyrroles from methyl 2-isocyanoacetate and α,β-unsaturated ketones. The choline hydroxide used is inexpensive, non-toxic, recyclable and environmentally friendly. Mild reaction conditions and an easy workup procedure are the striking features of this protocol. This transformation proceeds through the 1,4-conjugate addition of methyl 2-isocyanoacetate with α,β-unsaturated ketones followed by intramolecular cyclization–oxidation reaction.