C(OC([NH:8][C:9]1[CH:13]=[CH:12][S:11][C:10]=1[C:14]1[CH:19]=[CH:18][C:17]([Br:20])=[CH:16][CH:15]=1)=O)(C)(C)C.Cl.O.C([O-])(O)=O.[Na+]>C(OCC)(=O)C>[Br:20][C:17]1[CH:18]=[CH:19][C:14]([C:10]2[S:11][CH:12]=[CH:13][C:9]=2[NH2:8])=[CH:15][CH:16]=1A solution of (tert-butoxy)-N-[2-(4-bromophenyl)(3-thienyl)]carboxamide (10.8 g, 0.3 mmol, preparation 7) in ethyl acetate (75 mL) at 0° C., is treated dropwise with 244 mL (8 mL/mmol) of freshly prepared 1N HCl in ethyl acetate and the mixture is stirred at room temperature overnight. The white precipitate is dissolved with H2O (100 mL) and neutralized with a NaHCO3 saturated solution. The mixture is then extracted with ethyl acetate (3×100 mL) and the combined organics are dried and concentrated to give a slightly colored solid. Purification of the crude material by flash chromatography (Silica gel-Hexane/AcOEt 49:1 then 9:1) furnishes 5.7 g (74%) of title compound as a pale yellow solid.
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