Arylglyoxal oximes as putative C-nucleophiles in eliminative nucleophilic substitution process

Reaction of arylglyoxal oximes ArCOCH=NOH (Ar = 4-MeOC6H4, Ph) with 5-arylfurazanopyrazines proceeds as vicarious nucleophilic substitution of hydrogen in pyrazine ring with the elimination of hyponitrous acid, affording 5-(aroylmethylidene)-6-aryl-4H-furazano[3,4-b]pyrazines. Structure of the product was confirmed by X-ray diffraction.