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 (S)-3-[4-aminophenyl]-2-tert-butoxycarbonylamino-propionic acid methyl ester (37.57 g, 127.6 mmol) and 2,6-dichlorobenzoyl chloride (29.45 g, 140.6 mmol) in dichloromethane (350 mL) was added DIPEA (24.8 g, 192 mmol) at room temperature. The brown solution was stirred for 15 h at room temperature to afford a white suspension at this time TLC analysis of the mixture indicated the absence of starting material. Then, the solids were collected by filtration and the solids were washed with dichloromethane (150 mL) and air dried to obtain 52.75 g (88.4% yield) of (S)-2-tert-butoxycarbonylamino-3-[4-(2,6-dichlorobenzoylamino)phenyl]propionic acid methyl ester as a white solid: mp 192-194° C. ES(+)-HRMS m/e calcd. for C22H24Cl2N2O5 (M+H)+ 466.1062, obsd. 466.1069.

Provenance & Evidence