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

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Potassium cyanide (0.0377 g, 0.578 mmol), cesium chloride (0.0086 g, 0.051 mmol) and acetone cyanohydrin (0.142 ml, 1.55 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 (0.250 g, 0.512 mmol) in toluene (5.0 ml). To this vigorously stirred suspension was added antracen-9-yl-methyl quininium chloride (0.071 g, 0.129 mmol). The reaction mixture was stirred at 90° 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 (0.197 g, 79%) as a white foam. Chiral HPLC analysis (Chiralpack IB, Heptane:2-propanol=90:10, 1 ml/min, retention time 8.18 minutes (major enantiomer, minor enantiomer not observed), indicated that the reaction proceeded with >99% enantioselectivity.

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