Dichloromethane → HCID 11381978, compound

Participants

Reaction Conditions

Reaction Steps

Methyl ester (1.4 g) of N-tert-butoxycarbonyl-L-phenylalanine (1.4 g) was dissolved in dehydrated tetrahydrofuran (20 ml), and the obtained solution was cooled to −78° C. Methylene chloride (0.64 ml) and then 2 M solution (7.5 ml) of lithium diisopropylamide in heptane, tetrahydrofuran and ethylbenzene were added thereto, and they were stirred for 1 hour. A saturated aqueous ammonium chloride solution (20 ml) was added to the reaction mixture to terminate the reaction. The temperature was elevated to room temperature. After the extraction with ethyl acetate and water, the obtained solution in ethyl acetate was analyzed by HPLC to find that the intended (3S)-3-tert-butoxycarbonylamino-1,1-dichloro-4-phenyl-2-butanone (0.86 g) was obtained in a yield of 52%. The obtained solution in ethyl acetate was dried over anhydrous magnesium sulfate. Magnesium sulfate was filtered off. The solvent was evaporated under reduced pressure. Ethyl acetate was added to the residue to form a slurry. The crystals thus formed were separated from the slurry and dried to obtain the intended (3S)-3-tert-butoxycarbonylamino-1,1-dichloro-4-phenyl-2-butanone (0.65 g) in a yield of 36%.

Provenance & Evidence