Enantioselective Dearomative [3 + 2] Umpolung Annulation of N -Heteroarenes with Alkynes.

Enantioselective [3 + 2] annulation of N -heteroarenes with alkynes has been developed via a cobalt-catalyzed dearomative umpolung strategy in the presence of chiral ligand and reducing reagent. A variety of electron-deficient N -heteroarenes, including quinolines, isoquinolines, quinoxaline, and pyridines, and internal or terminal alkynes are employed in this reaction, showing a broad substrate scope and good functionality tolerance. Annulation of electron-rich indoles with alkynes is also developed. This protocol provides a straightforward access to a variety of N -spiroheterocyclic molecules in excellent enantioselectivities (76 examples, up to 99% ee).