Reactions of Benzocyclopropene with Sulfonyl Isocyanates and Nitrones: Cycloadditions through C–C σ-Bond Rupture of Three-Membered Ring

Abstract

Abstract Alkane- and arenesulfonyl isocyanates were added to benzocyclopropene across the C–C σ-bond of the three-membered ring, giving 2-sulfonyl-1-isoindolinones. The reaction with C,N-diphenylnitrone afforded a similar cyclization product, 3,4-dihydro-3,4-diphenyl-1H-2,3-benzoxazine. These reactions are considered to proceed through zwitterionic intermediates formed by the fission of the C–C σ-bond of the three-membered ring by the electrophiles.