1,4-Dioxane → Ethyl (7-bromo-3,4-dihydro-2H-1,4-benzoxazin-3-yl)acetate

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Reaction Steps

tert-Butyl 7-bromo-3-(2-ethoxy-2-oxoethyl)-2,3-dihydro-4H-1,4-benzoxazine-4-carboxylate (Intermediate 24, 556 mg, 1.39 mmol) was dissolved in hydrogen chloride in dioxane (5.0 mL, 162.8 mmol) and the mixture stirred for 2 h at rt. The solvent was evaporated and the residue dissolved in EtOAc (50 mL), washed with sat. aq. Na2CO3 (30 mL) and brine (20 mL), dried over Na2SO4 and evaporated after filtration to give the title compound (399 mg, 96%) as an oil.

Provenance & Evidence