2,6-Dichlorobenzoyl chloride → (S)-2-tert-butoxycarbonylamino-3-[4-(2,6-dichlorobenzoylamino)phenyl]propionic acid methyl ester

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Reaction Steps

To a solution of 4-(amino)-N-[(1,1-dimethylethoxy)carbonyl]-L-phenylalanine methyl ester (2.6 g, 8.6 mmol) in dichloromethane (20 mL) were added diisopropylethylamine (2.3 mL, 13 mmol) followed by 2,6-dichlorobenzoyl chloride (1.99 g, 9.5 mmol) at room temperature. The mixture was stirred for 15 h at which time a white precipitate was formed. The mixture was diluted with 30 mL of dichloromethane and 50 mL of water. The layers were separated and the aqueous layer was extracted with 100 mL (2×50 mL) of dichloromethane. The combined organic extracts were washed with brine and dried over anhydrous magnesium sulfate. Filtration and concentration of the solvent gave 4.03 g (quantitative) of 4-[[(2,6-dichlorophenyl)carbonyl]amino]-N-[(1,1-dimethylethoxy)carbonyl]-L-phenylalanine methyl ester as a white solid, mp 148-151° C.

Provenance & Evidence