Catalyst-free synthesis of quinoline-enols through coupling between heterocyclic N-oxides and CF3-ynones under mild conditions

Abstract

The coupling between heterocyclic N-oxides and CF₃-ynones has been demonstrated via the formal C–H and C–C bond cleavage under catalyst-free and mild conditions. This reaction displays a broad substrate scope of CF₃-ynone and heterocyclic N-oxide coupling partners (>60 examples). The gram scale synthesis and smooth transformation of the coupling adduct indicate the potential application of this approach. Preliminary mechanistic studies suggest that [3 + 2] annulation and the retro-Claisen reaction are the key steps for the formation of quinoline-enol scaffolds.