Metal-Free Addition of Alkyl Bromides to Access 3,3-Disubstituted Quinoxalinones Enabled by Visible-Light Photoredox Catalysis.

A metal-free addition of unactivated alkyl bromides to quinoxalin-2(1 H )-ones is described. This method enables the construction of valuable 3,3-disubstituted dihydroquinoxalin-2(1 H )-ones bearing quaternary carbon centers under mild, visible-light photoredox catalysis. High functional group tolerance is observed in both the quinoxalinone and alkyl bromide partners. The ability to scale up this method was demonstrated under photo-flow conditions to enable gram-scale synthesis.