Efficient synthesis of tetra- and penta-substituted benzenes via a domino annulation reaction of a pyridinium ylide and chalcone o-enolate

Abstract

A very simple and highly efficient protocol for synthesizing tetra- and penta-substituted benzene derivatives has been developed. This synthesis was achieved by carrying out a tetramethylguanidine (TMD)-promoted reaction of 4-(N,N-dimethylamino)-1-phenacyl-pyridinium bromide with chalcone o-enolates in DMF at 100 °C. The reaction mechanism was believed to involve a sequential annulation reaction of pyridinium ylide, ring-opening of the initially formed pyran ring and aromatization process.