CAN-catalyzed syntheses of 3,4-dihydroquinoxalin-2-amine derivatives based on isocyanides

Starting from readily available o-phenylenediamines 1, ketones 2 and isocyanides 3, a variety of highly substituted 3,4-dihydroquinoxalin-2-amine derivatives 4 were efficiently synthesized in the presence of catalytic amount of cerium(IV) ammonium nitrate at room temperature. The flexibility of this protocol also opens a new route to the structurally unique spirocyclic analogs when cyclic ketones are employed.