Toluene → 8-Fluoro-5-nitro-3,4-dihydro-2H-benzo[1,4]oxazine

Participants

Reaction Steps

To an ice-cold solution of [2-(2,6-difluoro-3-nitrophenoxy)ethyl]carbamic acid tert-butyl ester (450 mg, 1.416 mmol) in DCM (20 mL) was added TFA (4 mL). The reaction mixture was stirred at RT for 2.5 h, then toluene was added and volatiles were removed under reduced pressure. The resulting residue was dissolved in acetonitrile (10 mL), 2M Na2CO3 (10 mL) was added and the mixture stirred at RT for 1 h. The reaction mixture was partitioned between EtOAc and brine, the organic phase was dried (Na2SO4) and concentrated in vacuo. The residue was purified by column chromatography (Si—PCC, eluant 10-30% EtOAc in cyclohexane) affording the title compound as an orange solid (250 mg, 89%). 1H NMR (CDCl3, 300 MHz): 7.94 (1H, bs), 7.78 (1H, dd, J=9.7, 5.4 Hz), 6.45 (1H, t, J=9.5 Hz), 4.31 (2H, t, J=4.6 Hz), 3.70-3.66 (2H, m)

Provenance & Evidence