Synthesis of 6,7-ethylenedioxyquinoxalines and pyrido[2,3-b]pyrazines as intermediates in the preparation of antineoplastic agents

A convenient procedure for the synthesis of quinoxalines and pyridopyrazines has been developed from aryldiamines. The condensation of aminocarbamates such as with ethyl 2,3-dibromopropionate provide the quinoxaline directly, in a one-step operation. The methodology reported herein represents an alternative to condensation of o-phenylenediamines with α-dicarbonyl compounds for the quinoxalines formation. The same procedure was applied to the 2,3-diaminopyridine to obtain the corresponding pyridopyrazines.