Cross-dehydrogenative radical coupling enabled by K2S2O8: efficient synthesis of 2,3-dicarbonyl quinolines from enaminones and glycine derivatives

Abstract

Herein, we report a K₂S₂O₈-mediated metal-free radical dehydrogenative cross-coupling reaction that achieves direct C(sp²)–H/C(sp³)–H radical–radical coupling between N,N-dimethylenaminones and glycine derivatives. This reaction efficiently proceeds under oxidative conditions via a single-electron transfer (SET) mechanism, generating both enaminone radicals and α-amino radicals for subsequent coupling. This methodology enables one-step synthesis of 31 structurally diverse 2,3-dicarbonylquinoline derivatives, including 2,3-benzoylquinolines, 2,3-diester quinolines, and 2-ester-3-acylquinolines. This protocol establishes a robust foundation for future applications of such 2,3-dicarbonylquinoline compounds.