Formic Acid → 1,4-Benzoxazepine-4(5H)-carboxaldehyde, 2,3-dihydro-

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Reaction Steps

Acetic anhydride (30 ml),was added dropwise to formic acid (90 ml) at room temperature and after the mixture was stirred for 30 minutes, a solution of 2,3,4,5-tetrahydro-1,4-benzoxazepine (13.0 g) in ethyl acetate (50 ml) was added dropwise at:room temperature. The mixture was then stirred for 30 minutes, after which it was diluted with ice-water and extracted with ethyl acetate. The extract was washed successively with water, aqueous solution of sodium hydroxide (NaOH/H2O), and saturated aqueous solution of sodium chloride (NaCl/H2O) and dried over anhydrous magnesium sulfate (MgSO4). The solvent was then distilled off under reduced pressure and the residue was purified by silica gel column chromatography (eluent: ethyl acetate) to provide the title compound (14.4 g) as a viscous oil.

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