Dichloromethane → (S)-alpha-cyano-3-phenoxybenzyl (R)-2-(2-chloro-4-trifluoromethylphenylamino)-3-methylbutanoate

関与物質

反応手順

Into 4.5 ml of methylene chloride containing 22.5 mg of 4-dimethylaminopyridine are added 439 mg (1.48 mmol) of (R)-2-(2-chloro-4-trifluoromethylphenylamino)-3-methylbutanoic acid and 329 mg (1.46 mmol) of (S)-α-cyano-3-phenoxybenzyl alcohol. The solution is cooled in an ice bath and 380 mg (1.82 mmol) of dicyclohexylcarbodiimide is added. The mixture is stirred at 0° for 1 hour and is then worked up by partition between ether/hexane. The aqueous phase is extracted with ether, and the ether extract is washed with water (2×) and brine, dried over magnesium sulfate, filtered and evaporated. The product is purified by radial thin layer chromatography (2 mm silica gel rotor eluting with 12% ether/hexane). Higher diastereomeric purity is obtained by further radial tlc, yielding the final product (S)-α-cyano-3-phenoxybenzyl (R)-2-(2-chloro-4-trifluoromethylphenylamino)-3-methylbutanoate, specific rotation=+46.3° (in CHCl3), diastereomer purity=~98%.

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