Opening of the furan ring of 3-Nitrobenzofurans by the action of carbonyl-stabilized sulfonium ylides

Abstract

Upon treatment of 3-nitrobenzofurans with dimethylphenacylsulfonium salts in the presence of a base, the opening of the furan ring to form (E)-1-aryl-2-(dimethylsulfonio)-4-nitro-1-oxobut-3-en-2-ides takes place. The mechanism of nucleophilic dearomatization of 3-nitrobenzofurans involves consecutive carbo- and retro-oxa-Michael reactions. The reaction illustrates the high propensity of 3-nitrobenzofurans for ring opening.