2-Quinolinones are key scaffolds in pharmaceuticals, yet their synthesis under mild and sustainable conditions remains challenging. We report a transition-metal-free C(sp2)-H lactamization of azido-alkenes using CO2 as a one-carbon source. The reaction proceeds under mild conditions with dimethyl phenylphosphonite, affording 2-quinolinones with excellent functional-group tolerance. The method enables 13C-labeling with 99% incorporation, gram-scale synthesis, and downstream functionalizations, providing access to biologically relevant molecules. This strategy provides a versatile alternative to conventional and metal-catalyzed quinolinone syntheses.
Sun et al. (Mon,) studied this question.