Expeditious Synthesis of Papilionaceous Molecules Containing Oligobenzofurans

An efficient synthetic route to construct particular papilionaceous molecules containing oligobenzofurans is described. The key steps involved composing the backbone of the molecules by the Sonogashira cross-coupling reaction, followed by closing the benzofuran ring under alkaline conditions, and further aromatic cyclization of a multi-benzofuranyl precursor using ferric chloride as the oxidative reagent. Basic optical studies (UV-Vis, fluorescence, and fluorescence quantum yield) have been carried out on the synthesized molecules.