Nitromethane → 4-[(R)-3-(3,5-dichloro-phenyl)-4,4,4-trifluoro-3-nitromethyl-butyryl]-2-methyl-benzoic acid tert-butyl ester

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4-[(E)-3-(3,5-Dichloro-phenyl)-4,4,4-trifluoro-but-2-enoyl]-2-methyl-benzoic acid tert-butyl ester (0.0928 g, 0.198 mmol) and 1-[3,5-bis(trifluoromethyl)phenyl)-3-{(S)[(2S,4S,5R)-5-ethyl-1-aza-bicyclo[2.2.2]oct-2-yl]-(6-methoxy-4-quinolinyl)methyl}thiourea (0.0121 g, 0.020 mmol) were dissolved in nitromethane (0.6 ml) and the resulting solution was stirred at 50° C. for 2.5 days. The reaction mixture was cooled to room temperature and aqueous saturated ammonium chloride was added. The resulting mixture was extracted with dichloromethane (3×) and the combined organic fractions were dried over sodium sulfate. The crude product was purified by flash chromatography (0% to 5% ethyl acetate in cyclohexane) to afford 4-[(R)-3-(3,5-dichloro-phenyl)-4,4,4-trifluoro-3-nitromethyl-butyryl]-2-methyl-benzoic acid tert-butyl ester (0.080 g, 77%) as a beige solid. Chiral HPLC analysis (Chiralpack AS-RH, MeCN:MeOH:H2O=75:5:20, 1 ml/min, retention time 3.26 minutes (major enantiomer), 2.86 minutes (minor enantiomer) indicated that the reaction proceeded with 97.4% enantioselectivity.

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