Imidazolium ylides: Cycloaddition versus hydrolisis

Abstract

Reactions of imidazolium ylides with dimethyl acetylenedicarboxylate in polar solvents (methanol) were studied. In the competition between cycloaddition versus hydrolysis, the last one prevails leading to base heterocycle, diene structures and benzoate esters. A feasible reaction mechanism is presented. When fused pyrrolo-imidazole derivatives are desirable to be obtained, polar solvents should be avoided.