4-[(R)-3-Cyano-3-(3,5-dichloro-phenyl)-4,4,4-trifluoro-butyryl]-2-methyl-benzoic acid tert-butyl ester → 4-[(R)-4-(3,5-dichloro-phenyl)-4-trifluoromethyl-4,5-dihydro-3H-pyrrol-2-yl]-2-methyl-benzoic acid tert-butyl ester

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Reaction Steps

Alternatively, the title compound can be obtained by carrying out the following experiment: To a vigorously stirred solution of 4-[(R)-3-Cyano-3-(3,5-dichloro-phenyl)-4,4,4-trifluoro-butyryl]-2-methyl-benzoic acid tert-butyl ester (150 mg) in ethanol (9 mL) was added Raney Nickel (1.44 g, 50% suspension in water, previously washed with dry ethanol) and the reaction was stirred at room temperature under hydrogen (1 atm) for 2 hours then under arong overnight. Then the solution was filtered over celite, and the resulting filtrate was concentrated in vacuo to give the title compound (138 mg) as a pale yellow oil. The crude product was purified by flash chromatography (15% dichloromethane in ethyl acetate) to afford 4-[(R)-4-(3,5-dichloro-phenyl)-4-trifluoromethyl-4,5-dihydro-3H-pyrrol-2-yl]-2-methyl-benzoic acid tert-butyl ester as a pale yellow oil (0.070 g). Chiral HPLC analysis (Chiralpack IA, Heptane:2-propanol:diethylamine=90:10:0.1, 1 ml/min, retention time 5.93 minutes (major enantiomer), 8.57 minutes (minor enantiomer).

Provenance & Evidence