Trifluoroacetic acid → 2-Quinoxalinecarboxamide

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Reaction Steps

To the lactone from Example 2, method C (100 mg, 0.27 mmol), was added neat trifluoroacetic acid (1 mL). The resulting solution was stirred for 1 hour and the trifluoroacetic acid removed in vacuo. The remaining residue was solvated in methylene chloride (10 mL) and triethylamine (0.15 mL, 1.07 mmol). Quinoxalyl chloride (58 mg, 0.3 mmol) was added as a solid and the mixture stirred for 18 hour. The mixture was transferred to a separatory funnel and washed with citric acid (2×10 mL), NaHCO3 (10 mL) and brine (10 mL). The organic layer was dried (MgSO4) and the solvents filtered. The filtrate was concentrated in vacuo and the resulting residue was chromatographed on silica gel (10 g) eluting with 2:1 hexanes:ethyl acetate to provide 99 mg of the quinoxaline amide. This material was solvated in methanol and ammonia gas was bubbled in for 5 minutes. The resulting solution was stirred for 16 hours and the solvent removed in vacuo. The remaining residue was recrystallized (methylene chloride/methanol/Hexanes) to provide the title compound (90 mg, 72%). 1H NMR (400 MHz, CD3OD): d 9.38 (1H, s), 8.21 (1H, dd, J=4.4, 2.5 Hz), 8.14 (1H, dd, J=4.4, 2.5 Hz), 7.93 (2H, m), 7.26 (2H, d, J=6.9 Hz), 7.17 (2H, t, J=7.1 Hz), 7.09 (1H, t, J=7.3 Hz), 4.30 (1H, m), 3.75 (1H, m), 3.03-2.98 (2H, m), 2.47 (1H, m), 1.77 (1 H, m), 1.56 (2H, m), 1.4 (2H, m), 1.07 (6H, s).

Provenance & Evidence