Palladium-Catalyzed Cross-Coupling of 2-Chloroquinoxaline N-Oxides with Arylboronic Acids†

A selection of 2-chloro-substituted O-alkylquinoxaline N-oxides, easily accessible by the one-step annulation reaction of 4-fluoroaniline with 1,1,2-trichloro-2-nitroethylene and subsequent O-alkylation, was arylated at the chloronitrone unit in yields up to 96 %. This first efficient Pd-catalyzed Suzuki–Miyaura reaction of chloroquinoxaline N-oxides with arylboronic acids led to new 2-arylquinoxaline N-oxides. The scope and limitations of this arylation reaction were investigated, and the role of some sterically demanding boronic acids in the cross-coupling reaction was evaluated by means of DFT calculations. Additionally, the Pd-catalyzed C-arylation of the amide unit of selected quinoxalinone derivatives was accomplished.