Copper(II) Acetate Mediated Synthesis of 3-Sulfonyl-2-aryl-2H-chromenes

Abstract

This paper describes a concise, easy-operation, high-yielding method for the synthesis of 3-sulfonyl-2-aryl-2H-chromenes by a one-pot, straightforward two-step synthetic route, which includes (i) Cu(OAc)2/PyBOP-mediated intermolecular [4+2] annulation of substituted salicylic acids with β-sulfonylstyrenes in the presence of DMAP in refluxing DMF, and (ii) sequential O-alkylation of the resulting sulfonylflavanones with n-butyl bromide. A plausible mechanism is proposed and discussed. This protocol provides a highly effective annulation via one carbon–oxygen (C–O) and one carbon–carbon (C–C) bond formations.