Palladium-catalyzed C–H arylation of quinoxalin-2(1H)-ones with triarylantimony difluorides

Abstract

3-Arylquinoxalin-2(1H)-one derivatives are promising as biologically active substances. Herein, the reaction of quinoxalinones with triarylantimony difluorides (Ar3SbF2) in the presence of Pd(OAc)2 (10 mol%) and 2,2′-bipyridyl (10 mol%) at 130 °C in DMF under oxygen produced 3-arylquinoxalinones in good-to-excellent yields. This study represents the first example of Pd-catalyzed C–H arylations using non-aromatic heterocycles including C=N double bonds with pentavalent organoantimony compounds. The use of Ar3SbF2 enables the insertion of an aryl group even in the presence of an electron-withdrawing group on the benzene ring, which has been difficult thus far with conventional aryl group donors such as arylboronic acids, arylsiloxanes, and arylsulfonyl chlorides. Single crystal X-ray analysis of tris(p-trifluoromethylphenyl)antimony difluoride reveals that the central antimony atom exhibits a trigonal bipyramidal geometry.