Reactivity of electrogenerated N-heterocyclic carbenes in room-temperature ionic liquids. Cyclization to 2-azetidinone ring via C-3/C-4 bond formation

Abstract

The intrinsic chemistry of imidazolium-based room-temperature ionic liquids, related to the acidity of the C-2 imidazolium cation, can be modified via cathodic cleavage of the C-2/hydrogen bond. N-Heterocyclic carbenes, electrogenerated by electrolysis of imidazolium-based room-temperature ionic liquids, are stable bases that are strong enough to deprotonate bromoamides 1a-k yielding the azetidin-2-one ring via C-3/C-4 bond formation. The electrosynthesis of β-lactams 2a-k has been achieved under mild conditions, elevated yields and avoiding the use of toxic, volatile, molecular solvents. © 2008 Wiley-VCH Verlag GmbH & Co. KGaA.