Acetic Anhydride → HCID 140557999, compound

Participants

Reaction Conditions

Reaction Steps

3-Chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)-3-chloro-4-hydroxyimino-1,4,5,6-tetrahydropyridine-2-carboxylic acid methyl ester (34, 756 mg, 2.08 mmol) was slurried in glacial acetic acid (10 mL). Acetic anhydride (241 mg, 2.36 mmol) was added dropwise at room temperature. The reaction mixture was heated at 80° C. for 2 h. The solution was concentrated under vacuum, and the residue was dissolved in CH2Cl2 (50 mL) and washed with saturated aqueous NaHCO3 solution. The extracts were washed with brine, dried (MgSO4) and evaporated to give 3-chloro-6-(4-chloro-2-fluoro-3-methoxyphenyl)-4-[(E)-acetoxyoximino]-3-chloro-1,4,5,6-tetrahydropyridine-2-carboxylic acid methyl ester (35; 842 mg, 99%) as a light orange solid: 1H NMR (400 MHz, CDCl3) δ 7.21 (dd, JF-H=1.5 Hz, JH-H=8.4 Hz, 1H, aromatic), 7.11 (dd, JF-H=6.9 Hz, JH-H=8.4 Hz, 1H, aromatic), 5.24 (br s, 1H, NH), 4.76 (dd, J=4.2, 12.3 Hz, 1H, H5a), 3.98 (d, JF-H=1.5 Hz, 3H, OMe), 3.94 (s, 3H, CO2Me), 3.40 (ddd, JF-H=1.8 Hz, JH-H=4.2, 16.5 Hz, 1H, H6), 2.72 (dd, J=12.3, 16.5 Hz, 1H, H5b), 2.23 (s, 3H, NOAc). HRMS calcd for C16H15Cl2FN2O5: 404.034. Found: 404.034.

Provenance & Evidence