Synthesis of 2-arylbenzofuran-3-carbaldehydes via an organocatalytic [3+2] annulation/oxidative aromatization reaction

A novel organocatalytic [3+2] annulation/oxidative aromatization reaction of enals with 2-halophenols or β-naphthols is reported. This process enables chemo- and regioselective access to 2-arylbenzofuran-3-carbaldehydes without the use of transition metals or strong oxidants. Preliminary mechanistic studies reveal that an unprecedented, organocatalytic, direct α-arylation pathway is involved.