[CH3:1][O:2][C:3]1[C:4]([NH:15][NH2:16])=[N:5][C:6]2[C:11]([N:12]=1)=[CH:10][C:9]([O:13][CH3:14])=[CH:8][CH:7]=2.[C:17](OCC)(OCC)(OCC)[CH2:18][CH3:19]>>[CH2:18]([C:19]1[N:5]2[C:6]3[C:11]([N:12]=[C:3]([O:2][CH3:1])[C:4]2=[N:15][N:16]=1)=[CH:10][C:9]([O:13][CH3:14])=[CH:8][CH:7]=3)[CH3:17]A mixture consisting of 4.0 g. (0.018 mole) of 3,6-dimethoxy-2-hydrazinoquinoxaline, the product of Preparation E(d), and 50 ml. of triethyl orthopropionate was heated with mechanical stirring in a preheated oil bath at 100° C. overnight (~16 hours). The resulting reaction mixture was then cooled to room temperature (~20° C.), and the precipitate which formed was subsequently recovered by means of suction filtration and washed with ethanol to ultimately afford 3.3 g. (72%) of pure 4,7-dimethoxy-1-ethyl-[1,2,4]triazolo[4,3-a]quinoxaline, m.p. 184°-188° C. Mass Spectrum: m/e 258 (P); m/e, 228 (P-30).
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