This estimated 80% pure (E)-(3-chloro-4-methanesulfonyl-phenyl)-isopropoxyimino-acetic acid (prepared as in Example 6, 99 mg, 0.31 mmol), 2-aminobenzothiazole (512 mg, 0.34 mmol) and N,N-diisopropylethylamine (162 μL, 0.93 mmol) were combined in acetonitrile (1.25 mL) and cooled in an ice bath. O-(7-Azabenzotriazole-1-yl)-N,N,N′N′-tetramethyluronium hexafluorophosphate (118 mg, 0.31 mmol) was added and the ice bath was removed. After stirring 2 h, the reaction mixture was evaporated in vacuo. The residue was treated with saturated aqueous sodium bicarbonate solution (1 mL) and extracted with chloroform (2×3 mL). The combined organic phases were dried over sodium sulfate and evaporated in vacuo. The residue was purified by flash column chromatography (Merck silica gel 60, 40-63 μm; 50% ethyl acetate/hexanes) to afford (E)-N-benzothiazol-2-yl-2-(3-chloro-4-methanesulfonyl-phenyl)-2-isopropoxyimino-acetamide (76 mg, 54%) as a white solid after lyophilization from aqueous acetonitrile: LC-MS (ESI) m/e calcd for C19H18ClN3O4S2 [M+] 451.04, found 452 [M+H+]; H1-NMR (400 MHz, CDCl3) δ ppm 1.39 (d, J=6.3 Hz, 6 H, 2×CH3), 3.32 (s, 3 H, SO2CH3), 4.65 (m, J=6.3 Hz, 1 H, OCH), 7.36 (brt, J=7.8 Hz, 1H, Ar), 7.49 (brt, J=7.8 Hz, 1H, Ar), 7.64 (dd, Jo=8.2, Jm=1.6 Hz, 1 H, Ar), 7.74 (d, Jm=1.6 Hz, 1 H, Ar), 7.84 (m, 2H, Ar), 8.24 (d, Jo=8.2 Hz, 1 H, Ar), 10.20 (s, 1 H, NH).
