Light-Induced 1,4-Difunctionalization of Doubly Activated Cyclopropanes for the Synthesis of 3-Ethylacylamino-2-quinolones.

Two methods for the synthesis of 3-ethylacylamino-2-quinolones through the light-induced 1,4-difunctionalization of doubly activated cyclopropanes were described. These methods were conducted under mild, oxidant-free, and transition-metal-free conditions, with a broad scope of substrates and good functional group tolerance, leading to the synthesis of 3-ethylacylamino-2-quinolones that can be easily scaled up to the gram scale. Studies on the reaction mechanism indicate that the reaction involves the propagation of radical chains and the combination of Ritter-type and Combes/Conrad-Limpach-type reaction pathways.