Synthesis of poly functionalized pyridine derivatives from sulfonolketenimines, tetramethylguanidine and acetylenic esters

Pyridines, especially the poly substituted pyridines are among the most prevalent heterocyclic structural units in pharmaceutical and agrochemical targets, as well as inmaterials science [1]. Ketenimines, as useful intermediates, have attracted much attention due to their diverse chemistry and relative reactivity [2]. Due to the activity of the central carbon atom of ketenimines towards various nucleophiles, they are applied in the construction of heterocycles [3]. Herein, we report a simple and efficient procedures for the synthesis of dimethyl 6-(dimethylamino)-4-(4- methylphenylsulfonamido)-5-phenylpyridine-2,3-dicarboxylate via the Cu-catalyzed four-component coupling reaction of acetylene dicarboxylates, 1,1,3,3- tetramethylguanidine, sulfonyl azides and terminal alkynes (Fig. 1). The structures of products were characterized by their IR, 1H NMR, 13C NMR and mass spectral data. Various advantages of these transformations will be presented and discussed