N-Oxide as a Traceless Oxidizing Directing Group: Mild Rhodium(III)-Catalyzed C—H Olefination for the Synthesis of ortho-Alkenylated Tertiary Anilines

摘要

Tertiary anilines are important structural motifs frequently found in pharmaceuticals, dyes, natural products, biologically active molecules, and organic functional materials, and their functionalization has been attracting great interest in the synthetic organic chemistry community. It is well known that the electron-donor characteristics and the steric hindrance of tertiary amino groups commonly lead to the preferential para-functionalization of anilines through the Friedel-Crafts pathway and renders the ortho-selective C—H functionalization of tertiary anilines difficult. Therefore, the transition-metal-catalyzed chelation-assisted aromatic C—H functionalization through a cyclometalation should be an ideal strategy to meet these substantial challenges.