Visible light-promoted synthesis of 2-aryl-(3-organoselanyl)thieno[2,3-b]pyridines

We describe a simple and environment-friendly visible light-promoted protocol to access 2-aryl-(3-organoselanyl)thieno[2,3-b]pyridines, through the selenocyclization of 3-(arylethynyl)-2-(alkylthio)pyridines in the presence of diorganyl diselenides as selenium source. The Se-based reactive species were generated in situ by the homolytic Se-Se bond cleavage using blue LED in an O2 atmosphere at room temperature. The protocol was suitable for a wide range of substrates bearing different substituents, allowing the synthesis of twenty-one thieno[2,3-b]pyridines in good to excellent yields (57–99%).