Benzyne 1,2,4-Trisubstitution and Dearomative 1,2,4-Trifunctionalization

Both 1,2,4-trisubstitution and dearomative 1,2,4-trifunctionalization of benzyne have been accomplished from sulfoxides bearing a penta-2,4-dien-1-yl moiety. These cascade transformations proceed through a benzyne insertion into the S═O bond and an uncommon regiospecific anionic [4,5]-sigmatropic rearrangement, furnishing a C–O, C–S, and C–C bond on the C1-, C2-, and C4-position of a benzene ring, respectively. This study showcases new cascade benzyne reaction modes involving both distal C–H bond functionalization and dearomatization.