Switching Copper(II)-Catalytic Process for the Selective Access to C3-Imidazolyl- and Pyridylquinoxalin-2(1H)-ones

Abstract

A simple pseudofour-component reaction catalyzed by CuBr<inf>2</inf> has been developed to deliver C3-imidazoylquinoxalinones with decent yields from quinoxalin-2(1H)-ones, acetophenones, and ammonium persulfate in DMSO. This process follows a sequence of cross-dehydrogenative coupling/Kornblum oxidation/aza-cyclization, creating selectively four new C–C, two C–N, and C═N bonds. Interestingly, the Kornblum oxidation step can be skipped by simply replacing CuBr<inf>2</inf> with Cu(OAc)<inf>2</inf>. This alteration leads to high-value C3-pyridylquinoxalinones. Notably, DMSO serves both as a C–H source for pyridine ring synthesis and an effective solvent for this conversion. In addition, the acquired 3-imidazolyl- and pyridylquinoxalinones were transmuted into value-added 3-(imidazo[1,2-a]pyrazin-3-yl)quinoxalinone and 2-sulfonylquinoxalines, showcasing the synthetic utility of our method. © 2026 American Chemical Society