[H-].[Na+].[Br:3][C:4]1[CH:9]=[CH:8][C:7]([CH2:10][C:11]([O:13][CH3:14])=[O:12])=[C:6]([N+:15]([O-:17])=[O:16])[CH:5]=1.[I-].[Na+].Br[CH2:21][CH2:22][O:23][CH2:24][CH2:25]Br>CS(C)=O.[Cl-].[Na+].O>[Br:3][C:4]1[CH:9]=[CH:8][C:7]([C:10]2([C:11]([O:13][CH3:14])=[O:12])[CH2:25][CH2:24][O:23][CH2:22][CH2:21]2)=[C:6]([N+:15]([O-:17])=[O:16])[CH:5]=1Sodium hydride (0.32 g, 8.03 mmol, 60% dispersion in oil) was added in portions at rt to a stirred solution of methyl 2-(4-bromo-2-nitrophenyl)acetate (1 g, 3.65 mmol) in DMSO (15 mL). After the mixture was stirred at rt for 30 min, sodium iodide (0.055 g, 0.365 mmol) and bis(2-bromoethyl)ether (1.27 g, 5.47 mmol) were added. The resultant mixture was stirred at 40° C. After 19 h, the mixture was poured into brine with ice (50 mL) and extracted with EtOAc (3×50 mL). The combined extracts were washed with brine (3×80 mL), dried over Na2SO4, filtered, and evaporated in vacuo. The residue was purified by column chromatography (0 to 50% gradient of EtOAc in n-hexane) to give methyl 4-(4-bromo-2-nitrophenyl)tetrahydro-2H-pyran-4-carboxylate as an orange syrup. Mass Spectrum (ESI) m/e=344 [(M+1) (79Br)] and 346 [(M+1) (81Br)].
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