Hydrogen Bromide → 4-(2-Chloro-4-methylphenylcarbamoyl)-3-[4-cyclopropyl-5-(3-isobutylcyclobutyl)isoxazol-3-yl]butanoic acid

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Reaction Steps

tert-Butyl 4-(2-chloro-4-methylphenylcarbamoyl)-3-[4-cyclopropyl-5-(3-isobutylcyclobutyl)isoxazol-3-yl]butanoate (131 mg) and water (0.8 mL) were mixed. After an addition of 25 w/w % hydrogen bromide in acetic acid (1.64 mL) to the reaction mixture, the mixture was stirred at RT for 1.5 hr. Sodium acetate and water were added to the reaction mixture and the mixture was extracted with ethyl acetate. The organic layer was washed with water and brine, then dried over sodium sulfate. The sodium sulfate was filtered off and the filtrate was concentrated in vacuo. The resultant residue was purified by preparative chromatography (Eluent: methanol/chloroform=1/9) to give the title compound (97.3 mg). The specific optical rotation value of the title compound was [α]D25=+32.7° (c=1.00, methanol). The title compound was analyzed using a chiral column. The retention time of the title compound was 6.8 min., and the optical purity thereof was 95.1% ee. The condition for the analysis using the chiral column was as follows:

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