Br[C:2]1[CH:3]=[C:4]([CH:12]=[CH:13][CH:14]=1)[C:5]([O:7][C:8]([CH3:11])([CH3:10])[CH3:9])=[O:6].[CH3:15][S:16]([O-:18])=[O:17].[Na+].N1CCC[C@H]1C(O)=O.[OH-].[Na+]>[Cu]I>[CH3:15][S:16]([C:2]1[CH:3]=[C:4]([CH:12]=[CH:13][CH:14]=1)[C:5]([O:7][C:8]([CH3:11])([CH3:10])[CH3:9])=[O:6])(=[O:18])=[O:17]
The mixture of tert-butyl 3-bromobenzoate (7.0 g, 27.2 mmol), sodium methanesulfinate (4.45 g, 43.6 mmol), copper(I) iodide (0.52 g, 2.72 mmol), L-proline (0.63 g, 5.44 mmol) and sodium hydroxide (0.22 g, 5.44 mmol) was purged with nitrogen and DMSO was added. The mixture was heated to 80° C. After 18 h, the mixture was cooled to ambient temperature. Additional sodium methanesulfinate (2.78 g, 27.2 mmol), copper(I) iodide (0.52 g, 2.72 mmol), L-proline (0.63 g, 5.44 mmol) were added and the mixture was stirred at 80° C. for another 18 h. The mixture was cooled to ambient temperature and filtered with Celite. Lithium chloride (3.0 M in water) was added and the mixture was extracted with ethyl acetate (3×). The combined organic extracts were washed with LiCl (3.0 M in water), brine, dried over sodium sulfate, filtered and concentrated. Purification by silica gel chromatography (100% hexanes→75% hexanes/ethyl acetate) gave the title compound (5.05 g).
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