General procedure: Intermediate 13: Synthesis of 6-fluoro-3,4-dihydro-2H-benzo[1,4]oxazine
To a stirred mixture of 6-fluoro-2H-benzo[b][1,4]oxazin-3(4H)-one (0.9 g, 5.3 mmol) in THF (23 mL) was added dropwise a THF solution of lithium aluminum hydride (6.5 mL, 1 M) at 0 °C to -5 °C. The reaction mixture was stirred for 2 h at room temperature. Subsequently, the mixture was carefully poured onto ice and extracted with ethyl acetate. The organic phase was dried with anhydrous magnesium sulfate and concentrated under reduced pressure to remove the solvent. The residue was ground with ether to give 6-fluoro-3,4-dihydro-2H-benzo[1,4]oxazine (0.5 g, 61% yield) as a dark brown solid.
NMR (d6-DMSO) δ: 3.25 (2H, m), 4.05 (2H, m), 6.03 (1H, br s), 6.17 (1H, dt), 6.31 (1H, dd), 6.57 (1H, dd).
![6-FLUORO-3,4-DIHYDRO-2H-BENZO[1,4]OXAZINE HYDROCHLORIDE](/CAS/GIF/105655-00-3.gif)