Sulfuric Acid → HCID 19608698, compound

Participants

Reaction Conditions

Reaction Steps

A dry, 250 mL 3-neck round-bottom flask, equipped with a thermometer, magnetic stirring bar, reflux condenser and rubber septum was charged with 1-(3-fluoro-4-methoxyphenyl)-2-phenyl-ethan-1-one oxime from Step 2 (2.00 g, 7.71 mmol) and anhydrous THF (80 mL) under a nitrogen blanket. The solution was cooled to -20° C., and n-butyllithium (1.6 N, 12.0 mL) was added, via syringe, over 20 minutes, keeping the reaction temperature <-10° C. The deep red suspension was stirred at -20° C. for 1 hour, warmed to room temperature, and stirred at room temperature for 1 hour. Succinic anhydride (926 mg, 9.26 mmol) was added in one portion, and the yellow reaction was stirred for 16 hours without temperature control. Sulfuric acid (conc., 2.1 mL) was added, and the reaction was warmed to reflux. After 2 hours, the brown mixture was cooled to room temperature, diluted with water (100 mL), and extracted with ether (2×100 mL). The ethereal solution was extracted with dilute sodium hydroxide (2×100 mL), and the combined basic extracts were acidified to pH <2 with hydrochloric acid (conc.). The acidic system was extracted with ether (2×100 mL). This ethereal solution was evaporated under reduced pressure to a residue. The residue was applied to a column of silica gel (200 cc) and eluted (10% methanol in dichloromethane) to yield, upon concentration of the appropriate fractions, a crude solid. The solid was recrystallized from hot ethanol and 0.1 N HCl to yield, upon filtration and drying, [3-(3-fluoro-4-methoxyphenyl)-4-phenylisoxazol-5-yl]propanoic acid as ivory colored crystals (367 mg, 14%): mp 129-131° C. (dec). Mass Spectrum: MH+=342. 1H NMR (CDCl3 /300 MHz) δ 7.39 (m, 3H), 7.22-7.12 (m, 4H), 6.87 (t, J=8.46 Hz, 1H), 3.88 (s, 3H), 3.09 (t, J=8.05 Hz, 2H), 2.80 (t, J=8.05 Hz, 2H). 19F NMR(CDCl3 /282.2 MHz): -135.466 (m).

Provenance & Evidence