2,6-Lutidine → 4-(azidomethyl)-6-bromo-1-(4-methoxybenzyl)-4-(trifluoromethyl)-1,4-dihydro-2H-3,1-benzoxazin-2-one

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Reaction Steps

6-Bromo-4-(hydroxymethyl)-1-(4-methoxybenzyl)-4-(trifluoromethyl)-1,4-dihydro-2H-3,1-benzoxazin-2-one (61.3 g, 0.137 mol) was dissolved in chloroform (400 mL) and 2,6-dimethylpyridine (48.0 mL, 0.412 mol), and while stirring the solution at 0° C., trifluoromethanesulfonic anhydride (46.4 mL, 0.275 mol) was added dropwise thereto. After the reaction solution was stirred for 1 hour under ice-cooling, a saturated aqueous sodium hydrogen carbonate solution was added thereto. Then, the solution was diluted with ethyl acetate and the organic layer was separated. The organic layer was washed sequentially with a saturated aqueous ammonium chloride solution and saturated brine and then dried over magnesium sulfate. After the drying agent was removed by filtration, the solvent was evaporated under reduced pressure. The resulting residue was dissolved in DMF (270 mL), and sodium azide (26.7 g, 0.411 mol) was added thereto. After the reaction solution was stirred at 80° C. for 3 hours, the temperature of the solution was brought to room temperature and water was added thereto. The solution was diluted with ethyl acetate and the organic layer was separated. The organic layer was washed sequentially with an aqueous citric acid solution, water and saturated brine and then dried over magnesium sulfate. After the drying agent was removed by filtration, the solvent was evaporated under reduced pressure. The residue was purified by silica gel column chromatography (ethyl acetate/hexane=2/3) and further the resulting yellow solid was washed with hexane, whereby the objective compound (46 g, 71%) was obtained as a white solid.

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