Sulfuric Acid → o-(1-Hydroxy-4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)benzoic acid

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

Sodium hydroxide (0.58 g, 0.0145 mol) in water is added to a solution of methyl 2,3-dimethyl-2-[(1-oxo-2,3-benzoxazin-4-yl)amino]butyrate (2.0 g, 0.00689 mol) and tetrahydrofuran under a nitrogen atmosphere. The reaction mixture is stirred at 45° C. for 36 hours then at room temperature for 6 days. The reaction mixture is concentrated in vacuo to give an oil. The oil is dissolved into water. The aqueous solution is cooled with an ice-bath and concentrated sulfuric acid is added until a pH of about 1 is obtained then the solution is extracted with ethyl acetate. The combined ethyl acetate extracts are dried with anhydrous magnesium sulfate and concentrated in vacuo to give a pale yellow solid. The solid is added to boiling methylene chloride and after 2/3 of the methylene chloride has evaporated, the mixture is filtered to give the title compound as a white solid (1.44 g, 76%), mp 186°-188° C., identified by IR and NMR spectral analyses.

Herkunft & Nachweise