Cleavage of C–C Bonds for the Synthesis of C2-Substituted Quinolines and Indoles by Catalyst-Controlled Tandem Annulation of 2-Vinylanilines and Alkynoates

The strategy for the synthesis of C2-substituted indoles and quinolines from 2-vinylanilines and alkynoates through C-C bond cleavage is developed. With these general methods, 2-substituted indoles and quinolines can be accessed via tandem Michael addition and cyclization with no requirement of oxidant. This strategy not only provides a method for the synthesis C2-substituted indoles in good yields through the simultaneous cleavage of C═C and C≡C bonds under metal-free conditions but also provides a simple method for the generation of the C2-substituted quinolines in moderate yields via Pd-catalyzed C≡C bond cleavage.