Trifluoroacetic acid → HCID 69689400, compound

Participants

Reaction Conditions

Reaction Steps

1-(4-Methoxyphenyl)-2-(4-aminosulfonylphenyl-ethan-1-one oxime from Step 3 (1.2 g, 3.7 mmol), tetrahydrofuran (100 mL), and triethylamine (0.37 g, 3.7 mmol) were stirred at room temperature and treated with bis(1,2-chlorodimethylsilyl)ethane (0.80 g, 3.7 mmol). The solution was cooled to -78° C. under nitrogen. Lithium diisopropylamide (2.0M solution in heptane/tetrahydrofuran/ethylbenzene, 6.1 mL, 12.2 mmol) was added dropwise, and the cooling bath was removed. When the temperature reached -15° C., ethyl difluoroacetate (0.51 g, 4.1 mmol) was added. After stirring 0.5 hour, trifluoroacetic acid (30 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 NaHCO3, and water, dried over MgSO4, and concentrated. A dark oily solid was purified by flash column chromatography, eluting with ethyl acetate:hexane (1:1). The appropriate fractions were concentrated and crystallized from ethyl acetate/hexane to yield a white solid (0.21 g, 15%): mp 181.6°-182.6° C. 1H NMR (acetone-d6 /300 MHz) 8.0 (d, J=8.4 Hz, 2H), 7.6 (d, J=8.1 Hz, 2H), 7.5 (d, J=8.1 Hz, 2H), 7.4 (d, J=9.0 Hz, 2H), 7.1 (t, J=51.9 Hz, 1H), 6.7 (bs, 2H), 3.8 (s, 3H). Anal. Calc'd. for C17H14F2N2O4S: C, 53.68; H, 3.71; N, 7.36. Found: C, 53.71; H, 3.74; N, 7.27.

Provenance & Evidence