Sodium Hydroxide → 3-Methyl-2-furoic acid

To a solution of commercially available methyl 3-methylfuroate (20.0 g, 140 mmol) in 100 mL of MeOH, NaOH (11.43 g, 280 mmol) in 20 mL of water was added. The yellowish solution was stirred at room temperature for 3 hours. TLC (1:9 EtOAc/hexane) showed no starting material. MeOH was removed and the pH of the aqueous solution was adjusted to 4 with 1N HCl. The slurry was extracted with ethyl acetate (5×100 mL). The combined ethyl acetate layers were washed brine, and dried over sodium sulfate. 3-methyl furoic acid was obtained as a white solid (13.2 g, 73%) after evaporation of the solvent. To a mixture of 3-methyl furoic acid (8.60 g, 68 mmol), N,O-dimethylhydroxylamine hydrochloride (8.0 g, 82 mmol), EDC (15.7 g, 82 mmol), and HOBT (11.07 g, 82 mmol) in dichloromethane (200 mL), triethylamine (14.4 mL, 100 mmol) was added. The solution was stirred at room temperature for 4 hours, and washed with 1N NaOH (50 mL), 1N HCl (50 mL), brine, and dried over sodium sulfate. The title compound was obtained as a colorless liquid upon removal of the solvent. 1H NMR (CDCl3, 400 MHz): 7.40 (s, 1H), 6.38 (s, 1H), 3.81 (s, 3H), 3.36 (s, 3H), 2.38 (s, 3H).

1. customMeOH was removed
2. extractionThe slurry was extracted with ethyl acetate (5×100 mL)
3. washThe combined ethyl acetate layers were washed brine
4. dry with materialdried over sodium sulfate

ORD record

ord-b913f3b2040f4a2f94c1b9e1e2e0e19c

Source dataset

uspto-grants-2003_11

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06642237B1