Base-Catalysed (4+2)-Annulation Between 2-Nitrobenzofurans and N-Alkoxyacrylamides: Synthesis of [3,2-b]Benzofuropyridinones

An efficient protocol for base-catalysed (4+2) annulation between 2-nitrobenzofuran and N-alkoxyacrylamide was developed. The corresponding 1-alkoxy-3,4-dihydrobenzofuro[3,2-b]pyridin-2(1H)-ones were obtained in high to excellent yields by organic base catalysis. In addition, a dearomative nitrotetrahydrobenzofuro[3,2-b]pyridin-2(3H)-ones were also obtained in high yields in the presence of an inorganic base. The advantages of this methodology include easily accessible starting materials, simple operational procedures, broad substrate scope, and synthetically useful yields at milder reaction conditions.