[N:1]([CH2:4][C:5]1[O:6][CH:7]=[C:8]([OH:12])[C:9](=[O:11])[CH:10]=1)=[N+:2]=[N-:3].[OH-].[Na+].[CH2:15](Br)[C:16]1[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=1>CO>[N:1]([CH2:4][C:5]1[O:6][CH:7]=[C:8]([O:12][CH2:15][C:16]2[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=2)[C:9](=[O:11])[CH:10]=1)=[N+:2]=[N-:3]To a stirred solution of 2-azidomethyl-5-hydroxy-pyran-4-one (3) (70.0 g, 419.1 mmol) in methanol (500 mL) was added NaOH (20 g, 502.9 mmol, 2M) and benzyl bromide (60.14 mL, 502.9 mmol) and the reaction mixture was stirred at room temperature for 1 h. After completion of the reaction, solvent was evaporated to remove volatile compounds under reduce pressure, then it was diluted with water and extracted with ethyl acetate. Then the combined organic layer was washed with water and brine, dried over Na2SO4, concentrated under reduced pressure and purified using normal column chromatography (using 20% ethyl acetate in hexane) to get 2-azidomethyl-5-benzyloxy-pyran-4-one (4) (60.0 g, 55.0%) as a light brown solid.
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