Trifluoroacetic acid → HCID 69689575, compound

Participants

Reaction Conditions

Reaction Steps

1-(3-Fluoro-4-methoxyphenyl)-2-(4-aminosulfonylphenyl-ethan-1-one oxime from Step 3 (2.0 g, 5.9 mmol), and triethylamine (0.60 g, 5.9 mmol) were dissolved in tetrahydrofuran (100 mL) and treated with bis(1,2-chlorodimethylsilyl)ethane (1.27 g, 5.9 mmol) at room temperature. After 15 minutes, the solution was cooled to -78° C. and lithium diisopropylamide (2.0M solution in heptane/tetrahydrofuran/ethylbenzene, 7.75 mL, 19.5 mmol) was added dropwise. The solution was warmed to -15° C., and ethyl difluoroacetate (0.89 g, 6.5 mmol) was added. After stirring 0.5 hour, trifluoroacetic acid (40 mL) and water (10 mL) were added. The resulting dark mixture was heated to reflux for 20 hours, concentrated, dissolved in ethyl acetate (100 mL), washed with brine, saturated aqueous NaHCO3, and water, dried over MgSO4, and concentrated. A dark oily solid was crystallized from ethyl acetate/hexane to give a white solid (0.3 g, 13%): mp 188.2°-190.0° C. 1H NMR (acetone-d6 /300 MHz) 8.0 (d, J=8.4 Hz, 2H), 7.6 (d, J=8.7 Hz, 2H), 7.2 (m, 3H), 7.1 (t, J=51.9 Hz, 1H), 6.7 (bs, 2H), 3.9 (s, 3H). Anal. Calc'd. for C17H13F3N2O4S: C, 51.26; H. 3.29; N, 7.03. Found: C, 51.35; H, 3.33; N, 6.89.

Provenance & Evidence