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

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Reaction Steps

tert-Butyl 4-(2-Chloro-5-methylphenylcarbamoyl)-3-[4-cyclopropyl-5-(3-isobutylcyclobutyl)isoxazol-3-yl]butanoate (1.09 g) and toluene (3.2 mL) were mixed. To the mixture was added trifluoroacetic acid (3.2 mL) at ice temperature and the mixture was stirred at RT for 30 min. After water (5 mL) was poured into the reaction mixture dropwise at ice temperature, aqueous 4 N sodium hydroxide was added to the mixture dropwise and the mixture was extracted with ethyl acetate. The organic layer was washed with brine and dried over sodium sulfate. The sodium sulfate was filtered off and the filtrate was concentrated in vacuo. The resultant residue was purified by silica gel column chromatography (Eluent: ethyl acetate/hexane=1/5→1/3→1/2→2/1→methanol/chloroform=1/8) to give the title compound (905 mg). The title compound was analyzed using a chiral column. The retention time of the title compound was 6.6 min., and the optical purity thereof was 94.8% ee.

Provenance & Evidence