[CH3:1][O:2][C:3]([C:5]12[CH2:12][CH2:11][C:8](C(O)=O)([CH2:9][CH2:10]1)[CH2:7][CH2:6]2)=[O:4].[OH-].[Na+].[Br:18]Br>CC(C)=O.O.CCCCCC.[N+]([O-])([O-])=O.[Ag+].COC(C12CCC(C(O[Ag])=O)(CC1)CC2)=O>[Br:18][C:8]12[CH2:11][CH2:12][C:5]([C:3]([O:2][CH3:1])=[O:4])([CH2:10][CH2:9]1)[CH2:6][CH2:7]2To a suspension of 4-(methoxycarbonyl)bicyclo[2.2.2]octane-1-carboxylic acid (11.0 g, 51.8 mmol) in acetone (80 mL) was added 1 M aqueous sodium hydroxide solution (51.8 mL, 51.8 mmol). Then a solution of silver nitrate (8.8 g, 51.9 mol) in water (10 mL) was added. The formed precipitate was collected by filtration, washed with water, acetone and diethyl ether and dried in vacuo at 115° C. for 4 h. The obtained (4-(methoxycarbonyl)-bicyclo[2.2.2]octane-1-carbonyloxy)silver (15.3 g, 47.9 mmol) was suspended in hexane (125 mL), then bromine (7.7 g, 48.1 mmol) was added to the reaction mixture over 30 minutes at room temperature. After the addition was complete, the reaction mixture was stirred at room temperature for another 30 minutes. The reaction mixture was filtered to remove the solid, and the filter cake was washed with hexane (4×150 mL). The combined organic filtrates were washed with saturated sodium bicarbonate (2×150 mL) and brine (200 mL), and then dried over magnesium sulfate. Concentration under vacuum gave crude product, which was purified by silica gel column chromatography (5% ethyl acetate in petroleum ether) to afford the title compound (4.2 g, 0.17 mol, 33% yield in two steps). 1H NMR (400 MHz, CDCl3) δ ppm 3.64 (s, 3H), 2.27-2.20 (m, 6H), 1.98-1.94 (m. 6H).
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