Regioselective synthesis of 3-arylpyrido[2,3-b]pyrazines by reaction of arylglyoxals with 2,3-diaminopyridine

A series of pyrido[2,3-b]pyrazine derivatives were synthesized in good to excellent yields by condensation reactions of arylglyoxals with 2,3-diaminopyridine in dimethylformamide and ethanol at 90 oC.