Sodium Hydroxide → 2-Methoxyoxazole-5-carboxylic acid

Participants

Reaction Steps

To a solution of ethyl 2-chlorooxazole-5-carboxylate (510 mg, 2.90 mmol) in anhdryous MeCN (10 mL) and anhydrous MeOH (10 mL) is added NaOMe (628 mg, 11.62 mmol). The crude is stirred at reflux for 2 hrs. To this crude is added additional MeOH. The crude is refluxed for another 4 hrs. The crude is cooled and then concentrated and is redissolved in MeOH (10 mL). To this crude is added 1 N NaOH (10 ml, 10 mmol). The crude is stirred at room temperature for 3 hrs. The crude is quenched with concentrated HCl, PH adjusted to 7 via pH paper indicator. The crude is concentrated to remove MeOH. The crude is diluted in water. The aq. layer is acidified with concentrated HCl and diluted in EtOAc. The organic layer is washed with water, brine, dried over MgSO4, filtered, and concentrated to give 2-methoxyoxazole-5-carboxylic acid (290 mg). This acid is used without further purification. HPLC retention time=0.58 minutes (condition B); MS 144.0 (M+1).

Provenance & Evidence