Investigation of the Role of Electrogenerated N-Heterocyclic Carbene in the Staudinger Synthesis in Ionic Liquid

Electrogenerated N-heterocyclic carbene (NHC), obtained by cathodic reduction of Bmim-BF4, behaves as organocatalyst and base in the Staudinger synthesis from an acyl chloride and a deactivated imine in ionic liquid to yield β-lactams. The effect of many parameters (temperature, amount of electricity, substituents, presence of an external base) has been evaluated and a tentative mechanism for the Staudinger synthesis in a very polar medium like the ionic liquid reported. The yields of isolated β-lactams are good, starting from non-electrophilic imines, and predominantly trans lactams are obtained with a good diastereomeric ratio.