Regioselective synthesis of novel and diverse naphtho[1,2-b]furan-3-carboxamides and benzofuran-3-carboxamides by cascade formal [3 + 2] cycloaddition

Abstract

A novel and efficient In(OTf)₃-catalyzed cascade formal [3 + 2] cycloaddition of 1,4-naphthoquinones or benzoquinones with β-ketoamides was developed to provide naphtho[1,2-b]furan-3-carboxamides and benzofuran-3-carboxamides. This methodology has broad substrate scope that can afford novel and diverse naphtho[1,2-b]furan-3-carboxamides and benzofuran-3-carboxamides with high regioselectivity in good to excellent yields. Furthermore, this methodology is expected to be applicable to the synthesis of biologically-active complex molecules bearing naphtho[1,2-b]furan-3-carboxamides and benzofuran-3-carboxbenzamides.