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

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

Alternatively, to a solution of 1-[3,5-bis(trifluoromethyl)phenyl]-3-[(S)-(6-methoxy-4-quinolyl)-[(2S)-quinuclidin-2-yl]methyl]urea; prop-1-ene (09 mg, prepared according to the literature: Organic Letters 2007, 9, (14), 2621-2624) and nitromethane (0.6 ml) under argon, was added 4-[(E)-3-(3,5-Dichloro-phenyl)-4,4,4-trifluoro-but-2-enoyl]-2-methyl-benzoic acid tert-butyl ester (100 mg). The solution was heated for 3 days at 50° C. then allowed to stand at room temperature for 2 days. Water was then added and the resulting mixture was extracted with diethyl ether 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 (100 mg). Chiral HPLC analysis (Chiralpack IA, Heptane:2-propanol=90:10, 1 ml/min, retention time 6.43 minutes (major enantiomer), 7.78 minutes (minor enantiomer) indicated that the reaction proceeded with 95% enantioselectivity in favor of the R enantiomer.

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