Diisopropylethylamine → (2E)-2-(3-chloro-4-methylsulfonylphenyl)-2-cyclopentyloxyimino-N-(1,2-oxazol-3-yl)acetamide

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Reaction Steps

(E)-(3-Chloro-4-methanesulfonyl-phenyl)-cyclopentyloxyimino-acetic acid (prepared as in Example 1, 93 mg, 0.27 mmol), isoxazol-3-ylamine (29 □L, 0.30 mmol) and N,N-diisopropylethylamine (141 μL, 0.81 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 (103 mg, 0.27 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; 25% ethyl acetate/hexanes) to afford (E)-2-(3-chloro-4-methanesulfonyl-phenyl)-2-cyclopentyloxyimino-N-isoxazol-3-yl-acetamide (37 mg, 33%) as a slightly yellow solid after lyophilization from aqueous acetonitrile: LC-MS (ESI) m/e calcd for C17H18ClN3O5S [M+] 411.07, found 412 [M+H+]; H1-NMR (400 MHz, CDCl3) δ ppm 1.67 (m, 4 H, 2×CH2), 1.88 (m, 4 H, 2×CH2), 3.31 (s, 3 H, SO2CH3), 4.94 (m, 1 H, OCH), 7.07 (d, J=1.7 Hz, 1 H, Ar), 7.56 (dd, Jo=8.2, Jm=1.5 Hz, 1 H, Ar), 7.66 (d, Jm=1.5 Hz, 1 H, Ar), 8.20 (d, Jo=8.2 Hz, 1 H, Ar), 8.33 (d, J=1.7 Hz, 1 H, Ar), 9.40 (s, 1 H, NH).

Provenance & Evidence