1-Methylpiperazine → 1,2-Dihydro-8-(4-methylpiperazinyl)-4-phenylimidazo[1,2-a]quinoxaline 5-oxide

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Reaction Steps

1,2-Dihydro-8-fluoro-4-phenylimidazo[1,2-a]quinoxaline 5-oxide (3.5 g, 0.012 mol) and N-methylpiperazine (15 ml, 0.13 mol) were heated at 100° C. in isopropanol (5 ml) for 16 hrs. The solvent was removed in vacuo and the residue was dissolved in dichloromethane. The resulting solution was washed with saturated aqueous sodium hydrogen carbonate, dried over anhydrous magnesium sulphate and concentrated in vacuo to yield a dark oil which was chromatographed on silica gel in 2% methanol/chloroform to yield a red solid. The red solid was recrystallized from ethyl acetate to yield 1,2-dihydro-8-(4-methylpiperazinyl)-4-phenylimidazo[1,2-a]quinoxaline 5-oxide, (0.75 g), as deep red crystals m.p. 179°-183° C., (δ(CDCl3) 2.38 (3H,s) 2.58 (4H,m) 3.37 (4H,m) 3.95-4.24 (4H,m) 6.08 (1H,d,J=3.5Hz), 6.62 (1H,dd,J=9 and 3.5Hz), 7.38-7.5 (3H,m), 7.84 (2H,m), and 8.11 (1H,d,J=9 Hz)), represented by the structural formula: ##STR17##

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