8-Fluoro-3,4-dihydro-2H-benzo[1,4]oxazine hydrochloride

Synthesis

8-Fluoro-2H-1,4-benzoxazin-3(4H)-one (1.0 g, 5.9 mmol) was used as starting material, which was dissolved in THF (25 mL) and stirred to form a suspension at 0 °C to -5 °C. Subsequently, a THF solution of lithium aluminum hydride (7 mL, 1 M) was slowly added dropwise. After the dropwise addition, the reaction mixture was warmed to room temperature and stirring was continued for 2 hours. Upon completion of the reaction, the mixture was carefully poured into ice water to quench the reaction and extracted with ethyl acetate. The organic phases were combined, dried with anhydrous magnesium sulfate, filtered and concentrated under reduced pressure to remove the solvent. The resulting residue was ground with ether to afford 8-fluoro-3,4-dihydro-2H-benzo[1,4]oxazine (0.8 g, 87% yield) as a dark brown solid. Mass spectrum (ESI+): m/z 154 [M+H]+. 1H NMR (DMSO-d6): δ 3.27 (2H, m), 4.11 (2H, m), 6.05 (1H, br s), 6.34 (2H, m), 6.58 (1H, m).

References

[1] Patent: WO2011/144578, 2011, A1. Location in patent: Page/Page column 30
[2] Bioorganic and Medicinal Chemistry Letters, 2008, vol. 18, # 16, p. 4700 - 4704