Benzo(d)thiazol-2-amine → (2E)-N-(1,3-benzothiazol-2-yl)-2-(3-chloro-4-methylsulfonylphenyl)-2-cyclopentyloxyiminoacetamide

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Reaction Steps

(E)-(3-Chloro-4-methanesulfonyl-phenyl)-cyclopentyloxyimino-acetic acid (prepared as in Example 1, 96 mg, 0.28 mmol), 2-aminobenzothiazole (42 mg, 0.28 mmol) and N,N-diisopropylethylamine (145 μL, 0.83 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 (106 mg, 0.28 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-(3-chloro-4-methanesulfonyl-phenyl)-2-cyclopentyloxyimino-acetamide (93 mg, 70%) as a white solid after lyophilization from aqueous acetonitrile: LC-MS (ESI) m/e calcd for C21H20ClN3O4S2 [M+] 477.06, found 478 [M+H+]; H1-NMR (400 MHz, CDCl3) δ ppm 1.68 (m, 4 H, 2×CH2), 1.90 (m, 4 H, 2×CH2), 3.32 (s, 3 H, SO2CH3), 4.96 (m, 1 H, OCH), 7.35 (ddd, Jo=7.9, Jo=7.3, Jm=1.2 Hz, 1 H, Ar), 7.48 (ddd, Jo=8.2, Jo=7.3, Jm=1.2 Hz, 1 H, Ar), 7.61 (dd, Jo=8.2, Jm=1.6 Hz, 1 H, Ar), 7.72 (d, Jm=1.6 Hz, 1 H, Ar), 7.84 (m, 2H, Ar), 8.23 (d, Jo=8.2 Hz, 1 H, Ar), 10.21 (s, 1 H, NH).

Provenance & Evidence