Benzo(d)thiazol-2-amine → (2E)-N-(1,3-benzothiazol-2-yl)-2-cyclopentyloxyimino-2-(3,4-dichlorophenyl)acetamide

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Reaction Steps

(E)-Cyclopentyloxyimino-(3,4-dichloro-phenyl)-acetic acid (prepared as in Example 18, 100 mg, 0.33 mmol), 2-aminobenzothiazole (50 mg 0.33 mmol) and N,N-diisopropylethylamine (173 μL, 0.99 mmol) were combined in methylene chloride (1.6 mL) and cooled in an ice bath. O-(7-Azabenzotriazole-1-yl)-N,N,N′N′-tetramethyluronium hexafluorophosphate (126 mg, 0.33 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; 40% ethyl acetate/hexanes) to afford (E)-N-benzothiazol-2-yl-2-cyclopentyloxyimino-2-(3,4-dichloro-phenyl)-acetamide (96 mg, 67%) as a white solid after lyophilization from aqueous acetonitrile: LC-MS (ESI) m/e calcd for C20H17Cl2N3O2S [M+] 433.04, found 434 [M+H+]; H1-NMR (400 MHz, CDCl3) δ ppm 1.68 (m, 4 H, 2×CH2), 1.90 (m, 4 H, 2×CH2), 4.93 (m, 1 H, OCH), 7.34 (ddd, Jo=8.0, Jo=7.3, Jm=1.2 Hz, 1 H, Ar), 7.40 (dd, Jo=8.4, Jm=2.0 Hz, 1 H, Ar), 7.47 (ddd, Jo=8.3, Jo=7.3, Jm=1.3 Hz, 1 H, Ar), 7.53 (d, Jo=8.4 Hz, 1 H, Ar), 7.67 (d, Jm=2.0 Hz, 1 H, Ar), 7.83 (m, 2H, Ar), 10.20 (s, 1 H, NH).

Provenance & Evidence