Reaction #10373

Reaction equation

hydrochloric acid

2,4,5-Trifluoro-3-formylbenzoic acid

triethylamine

O-benzylhydroxylamine hydrochloride

→

3-(benzyloxyiminomethyl)-2,4,5-trifluorobenzoic acid

Yield 100.0%

Solvents

tetrahydrofuran

brine

Conditions

Workup

1. 1
   ExtractionThe mixture is extracted with ethyl acetate
2. 2
   DryingThe organic phase is dried over Na2SO4
3. 3
   Filtrationfiltered
4. 4
   Concentrationconcentrated in vacuo

Procedure

2,4,5-Trifluoro-3-formylbenzoic acid (Horiuchi N., Yonezawa T., Chiba K., Yoshida H., PCT Int. Appl. [1999] WO 97-JP2918), (5.70 g, 27.9 mmol), triethylamine (11 mL, 78.9 mmol), O-benzylhydroxylamine hydrochloride (4.47 g, 28.0 mmol) and anhydrous tetrahydrofuran (150 mL) are stirred at room temperature for 50 hours. The mixture is poured into brine and the pH adjusted to 5.5–6.0 using 1.0 M hydrochloric acid. The mixture is extracted with ethyl acetate. The organic phase is dried over Na2SO4, filtered, and concentrated in vacuo to provide 3-(benzyloxyiminomethyl)-2,4,5-trifluorobenzoic acid (8.63 g), which is used without further purification. 1H NMR (200 MHz, CDCl3): δ 9.82–9.18 (bs, 1H), 8.24 (s, 1H), 7.94–7.68 (m, 1H), 7.55–7.23 (m, 5H), 5.23 (d, 2H). MS (EI, M−1) m/z 308.

Source