Synthesis of 2‐Aryl‐(3‐Organochalcogenyl)Thieno[2,3‐b]Pyridines Promoted by Oxone®.

We describe herein an alternative method for the synthesis of 2‐aryl‐(3‐organochalcogenyl)thieno[2,3‐b]pyridines through the electrophilic cyclization of 3‐(arylethynyl)‐2‐(alkylthio)pyridines promoted by electrophilic species of organochalcogen compounds. These species were generated in situ by the oxidative cleavage of chalcogen‐chalcogen (Se, Te) bond of diorganyl dichalcogenides using Oxone® in ethanol as solvent in an open‐flask at 78 °C. The protocol allowed the synthesis of highly substituted thieno[2,3‐b]pyridines starting from several diorganyl dichalcogenides and 3‐(arylethynyl)‐2‐(alkylthio)pyridines, obtaining 21 new compounds in good to excellent yields (70–99%). Still, the method showed good efficiency on the gram‐scale synthesis. In addition, several synthetic transformations such as oxidation, selenylation and hydrogenation reactions were demonstrated. [ABSTRACT FROM AUTHOR]