Hydrochloric Acid → 6-Trifluoromethyl-3,4-dihydro-2H-benzo[1,4]oxazine-2-carboxylic acid

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Reaction Steps

6-Trifluoromethyl-3,4-dihydro-2H-benzo[1,4]oxazine-2-carboxylic acid ethyl ester (500 mg, 2 mmol) was dissolved in 1,4-dioxane (20 mL). Sodium hydroxide (109 mg, 2.7 mmol) was added, followed by benzyl chloroformate (311 μL, 2.2 mmol), and the reaction stirred overnight at room temperature. The reaction mixture was acidified with 2N HCl and diluted with water (20 mL), then extracted with EtOAc (3×30 mL). The combined organics were washed with brine (2×40 mL), dried (MgSO4), filtered and concentrated. Trituration using DCM/hexanes gave the title compound (330 mg, 10%) as a pale brown solid. m/z=245.7 (M−1), r.t.=2.78 mins. 1H NMR (400 MHz; CDCl3) δ 7.01 (2H, s), 6.86 (1H, s), 4.94 (1H, t), 3.66 (2H, dd).

Provenance & Evidence