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

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

Potassium cyanide (0.0090 g, 0.138 mmol) and acetone cyanohydrin (0.040 ml, 0.435 mmol) were added to a solution of 4-[(E)-3-(3,5-Dichloro-phenyl)-4,4,4-trifluoro-but-2-enoyl]-2-methyl-benzoic acid tert-butyl ester (0.0645 g, 0.140 mmol) in toluene (1.0 ml). To this vigorously stirred suspension was added 2,3,4,5,6-pentafluorophenyl-methyl quininium chloride (0.015 g, 0.028 mmol). The reaction mixture was stirred at 45° C. for 18 hours. At this time water was added and the reaction mixture was extracted with dichloromethane (3×). The crude product was purified by flash chromatography (0% to 5% ethyl acetate in cyclohexane) to afford 4-[(R)-3-Cyano-3-(3,5-dichloro-phenyl)-4,4,4-trifluoro-butyryl]-2-methyl-benzoic acid tert-butyl ester (0.048 g, 66%) as a white foam. Chiral HPLC analysis (Chiralpack IA, Heptane:2-propanol:diethylamine=95:5:0.1, 1 ml/min, retention time 6.52 minutes (major enantiomer), 6.02 minutes (minor enantiomer) indicated that the reaction proceeded with 88% enantioselectivity. 1H NMR (400 MHz, CDCl3) δ 7.89 (d, 1H), 7.78-7.72 (m, 2H), 7.48 (s, 2H), 7.46-7.42 (m, 1H), 4.17 (d, 1H), 4.02 (d, 2H), 2.62 (s, 3H), 1.62 (s, 9H)

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