Oxidative cross-coupling of quinoxalinones with indoles enabled by acidochromism.

An oxidative cross-coupling of quinoxalinones with indole derivatives via B(C 6 F 5 ) 3 ·H 2 O induced acidochromism of quinoxalinone derivatives was developed under mild and external photocatalyst-free conditions. The reaction shows excellent substrate scope, accommodating a wide range of functional groups. The usefulness of this strategy was demonstrated by the synthesis of the natural products Azacephalandole A and Cephalandole A in high yields. Moreover, the products are fluorophores showing prevalent fluorescence properties with a wide emission range and good relative quantum yields.