C[Si]([C:5]#[C:6][S:7]([C:10]1[CH:15]=[CH:14][C:13]([CH3:16])=[CH:12][CH:11]=1)(=[O:9])=[O:8])(C)C.[Br:17]N1C(=O)CCC1=O>CC(C)=O.[N+]([O-])([O-])=O.[Ag+]>[Br:17][C:5]#[C:6][S:7]([C:10]1[CH:15]=[CH:14][C:13]([CH3:16])=[CH:12][CH:11]=1)(=[O:9])=[O:8]To a stirred solution of trimethylsilyl p-tolylsulfonylacetylene (10 g, 40 mmol) in acetone (300 mL) was added silver nitrate (0.68 g, 4 mmol) followed by the addition of N-bromosuccinimide (7.6 g, 44 mmol) in one portion. The mixture was stirred at room temperature for 1 h. The resulting precipitate was filtered and washed with acetone. Silica gel (20 g) was added to the filtrate and the solvent was removed under reduced pressure. The residue was subjected to column chromatography with hexane/EtOAc (5:1) to afford the product as a light yellow solid (10 g, 96%). Mp. 99-101° C. 1H NMR (CDCl3) δ 7.87 (d, 2H, J=7.8 Hz), 7.39 (d, 2H, J=7.8 Hz), 2.47 (s, 3H); 13C NMR (CDCl3) δ 146.19, 138.16, 130.34, 127.83, 78.14, 61.70, 21.97.
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