Reactions of 2-Unsubstituted 1H-Imidazole 3-Oxides with Heterocumulenes and Dimethyl Acetylenedicarboxylate

Reaction of 2-unsubstituted 1H-imidazole 3-oxides with isocyanates, isothiocyanates, and dimethyl acetylenedicarboxylate led to the formation of 2-functionalized imidazole derivatives. Stepwise reaction mechanisms via zwitterionic intermediates are proposed. The intermediate [3+2] cycloadducts stabilize via extrusion of COX or ring opening.