Visible-light-induced C(sp)-H activation for a C-C bond forming reaction of 3,4-dihydroquinoxalin-2(1)-one with nucleophiles using oxygen with a photoredox catalyst or under catalyst-free conditions.

A convenient photocatalyzed oxidative coupling reaction of 4-alkyl-3,4-dihydroquinoxalin-2(1)-one and its derivatives with a variety of nucleophiles was developed with a ruthenium photoredox catalyst and oxygen under a household compact fluorescent light. With a slower reaction rate, the cross coupling transformation can be achieved in the absence of an external photocatalyst with a similar isolated yield. An application to the synthesis of natural product cephalandole A was also demonstrated.