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

• Jennie Liao^a, David N. Hunter^b, Ugochinyere Nancy Oloyede^b, Joseph W. McLaughlin^b, Cheng Wang^b, and Abdellatif El Marrouni^b

• ^aProcess Research & Development, MRL, Merck & Co., Inc., West Point, Pennsylvania 19486, United States
• ^bDiscovery Chemistry, MRL, Merck & Co., Inc., West Point, Pennsylvania 19486, United States

A metal-free addition of unactivated alkyl bromides to quinoxalin-2(1H)-ones is described. This method enables the construction of valuable 3,3-disubstituted dihydroquinoxalin-2(1H)-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.

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