Palladium-catalyzed intramolecular coupling of 2-[(2-pyrrolyl)silyl]aryl triflates through 1,2-silicon migration.

Palladium-catalyzed intramolecular direct arylation of 2-[(2-pyrrolyl)silyl]aryl triflates gives 3,2'-silicon-bridged 2-arylindoles and -pyrroles in good to high yields. The reaction proceeds through cleavage of C-OTf, C-Si, and C-H bonds to result in the formation of C-C and C-Si bonds. Various kinds of functional groups such as OMe, CN, Cl, F, and SiMe(3) tolerated the conditions. The new reaction allows synthesis of functionalized Si-bridged 2-arylindoles that emit intense and efficient blue fluorescence in the solid state.