1,3-Dipolar cycloaddition of azomethine ylides and imidoyl halides for synthesis of pi-extended imidazolium salts

A new synthetic approach to pi-extended imidazolium salts is developed based on 1,3-dipolar cycloaddition of polycyclic aromatic azomethine ylides with imidoyl chlorides, where the key to the successful conversion is the addition of cesium fluoride as an additive. Experimental and theoretical studies revealed that this cycloaddition proceeds via a stepwise mechanism rather than a concerted mechanism. This present method provides an efficient method to synthesize a variety of imidazolium-containing polycyclic aromatic compounds.