A one-pot synthesis of 2,3-dihydrobenzofurans, benzofuran-2(3H)-ones, and indoles via a [4 + 1] annulation reaction of ortho-substituted para-quinone methides and bromonitromethane

Abstract

Under mild and metal-free reaction conditions, a facile one-pot synthesis of oxygen- and nitrogen-containing benzoheterocycles has been achieved through [4 + 1] annulation of para-quinone methides, followed by an oxidation/elimination sequence, efficiently synthesizing functionalized 2,3-dihydrobenzofuran, benzofuran-2(3H)-one, and indole derivatives in moderate to good yields (up to 72%). A novel functional group tolerant oxidative Nef reaction utilizes DDQ without a base.