We report herein intramolecular (3+2) cycloaddition reactions between ynamides as three-atom components and benzyne. In these intramolecular reactions, the two-bond formation is realized by exploiting benzyne precursors that contain a chlorosilyl group as a linking functionality. This method thus highlights the ambivalent character of the intermediate indolium ylide, which exhibits both nucleophilic and electrophilic properties at its C2 atom.

We report herein intramolecular (3+2) cycloaddition reactions between ynamides as three-atom components and benzyne. In these intramolecular reactions, the two-bond formation is realized by exploiting benzyne precursors that contain a chlorosilyl group as a linking functionality. This method thus highlights the ambivalent character of the intermediate indolium ylide, which exhibits both nucleophilic and electrophilic properties at its C2 atom.

A variety of highly functionalized allenes and allenamides are prepared by an intramolecular propargylic ene reaction of benzyne. A particular benzyne precursor having chlorodiisopropylsilyl group served as a platform to link with various propargyl alcohols via a Si–O bond, expanding the scope of this reaction. Also noted was a complete transmission of point to axial chirality was demonstrated to give a chiral, non-racemic allenamide.