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 Re2 (CO)10 , Me2 Zn 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 Re2 (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.