Pd-Catalyzed Intramolecular Cyclization via Direct C–H Addition to Nitriles: Skeletal Diverse Synthesis of Fused Polycyclic Indoles

The first example of Pd-catalyzed intramolecular C–H addition of indoles bearing cyanohydrin components at the C(3), C(2), and N(1) positions to nitriles is described. A wide range of functionalized partially saturated carbazoles, tetrahydropyrido[1,2-a]indole, and carbazoles can be prepared in good to excellent yields under the optimal conditions. In addition, fused polycyclic indoles with seven- or eight-membered rings can also be formed smoothly.