Swift and Efficient Synthesis of 4-Phenylquinazolines: Involvement of N-Heterocyclic Carbene in the Key Cyclization Step

An original route to 2-alkyamino-4-phenylquinazolines in three steps from simple (hetero)aromatic amines is reported here. The key step involves the intramolecular cyclization of benzoyl arylguanidines performed in [OMIm]Cl ionic liquid. The basic (hetero)aromatic guanidines deprotonate the imidazolium-based Ionic liquid, thus triggering the cascade process ultimately leading to the intramolecular cyclization. This reaction is the first example of a Friedel-Crafts-type reaction in which an N-heterocyclic carbene is involved in the formation of the electrophilic intermediate.