Hydrogen chloride-ethyl acetate → 8-Isopropoxy-2,3,4,5-tetrahydropyrido[3,2-f][1,4]oxazepine

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Reaction Steps

A mixture of the compound obtained in Example 4, step 1 (0.60 g), 4N hydrogen chloride/ethyl acetate (5 mL) and ethyl acetate (5 mL) was stirred at room temperature for 3 hr. The precipitate was collected by filtration, and the aqueous layer was basified and extracted with ethyl acetate and aqueous sodium hydroxide solution. The organic layer was washed with saturated brine and dried, and the solvent was evaporated under reduced pressure. The residue was purified by basic silica gel column chromatography (solvent gradient; 0→40% ethyl acetate/hexane), 0.5M succinic acid/methanol solution was added, and the solvent was evaporated under reduced pressure. The obtained residue was recrystallized from ethyl acetate-hexane to give the title compound (0.032 g, 6%) as a white powder.

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