Water → 4-(3-Oxo-2,3-dihydro-benzo[1,4]oxazin-4-yl)-piperidine-1-carboxylic acid tert-butyl ester

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Reaction Steps

1-(tert-Butoxycarbonyl)-4-[(2-carboxymethoxyphenyl)amino]piperidine (351 mg) was dissolved in dichloroethane (7 ml), added with thionyl chloride (73 μl) and stirred at room temperature for 1.5 hours. The reaction mixture was added with triethylamine (0.28 ml) and further stirred at 40° C. for 2 hours. The reaction mixture was added with water (10 ml) and extracted twice with ethyl acetate (10 ml). The organic layer was dried over anhydrous magnesium sulfate, and then the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (elution solvent: hexane:ethyl acetate=2:1) to obtain 191 mg of the title compound. Yield: 57%.

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