Re-Catalyzed Annulations of Weakly Coordinating N-Carbamoyl Indoles/Indolines with Alkynes via C-H/C-N Bond Cleavage

Described herein are rhenium-catalyzed [3+2] annulations of N-carbamoyl indoles with alkynes via C-H/C-N bond cleavage, which provide rapid access to fused-ring pyrroloindolone derivatives. For the first time, the weakly coordinating O-directing group was successfully employed in rhenium-catalyzed C-H activation reactions, enabled by the unique catalytic trio of Re-2(CO)(10), Me2Zn and ZnCl2. Mechanistic studies revealed that aminozinc species plays an important role in the reaction. Based on the mechanistic understanding, a more powerful catalytic trio of Re-2(CO)(10), [MeZnNPh2](2) and Zn(OTf)(2) was devised and applied successfully in the [4+2] annulations of indolines and alkynes affording pyrroloquinolinone derivatives.