[Br:1][C:2]1[N:7]=[CH:6][C:5]([CH:8]([OH:12])[CH2:9][O:10][CH3:11])=[CH:4][CH:3]=1.[O:13]1[CH:18]=[CH:17][CH2:16][CH2:15][CH2:14]1.C(=O)([O-])O.[Na+]>O.C1(C)C=CC(S(O)(=O)=O)=CC=1.O1CCCC1>[Br:1][C:2]1[CH:3]=[CH:4][C:5]([CH:8]([O:12][CH:14]2[CH2:15][CH2:16][CH2:17][CH2:18][O:13]2)[CH2:9][O:10][CH3:11])=[CH:6][N:7]=1To a mixture of 1-(6-bromopyridin-3-yl)-2-methoxyethanol (15.26 g), p-toluenesulfonic acid monohydrate (0.63 g) and tetrahydrofuran (65 ml) was added 3,4-dihydro-2H-pyran (7.76 g) at room temperature over 30 min, and the mixture was stirred for 2 hr. To the reaction mixture was added saturated aqueous sodium hydrogen carbonate, and the mixture was extracted with ethyl acetate. The ethyl acetate layer was washed with saturated brine, dried (MgSO4) and concentrated. The obtained residue was subjected to silica gel column chromatography, and the title compound (19.66 g, yield 94%) was obtained as a colorless oil from a fraction eluted with ethyl acetate-hexane (2:3, volume ratio). MS: 318 (MH+).
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