Oxalyl chloride → t-butyl-(1S)-2-chloro-1-[3,5-difluorobenzyl]-2-oxoethylcarbamate

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Reaction Steps

(2S)-2-[(tert-butoxycarbonyl)amino]-3-(3,5-difluorophenyl)propanoic acid (I) is dissolved in THF and stirred at 20-25°. Oxalyl chloride (1 equivalent) is added and the mixture stirred for about 15 min to give t-butyl-(1S)-2-chloro-1-[3,5-difluorobenzyl]-2-oxoethylcarbamate (XI). The mixture is cooled to <0° and LiCHICl (greater than 2 equivalents) is added. The mixture is stirred until the reaction is complete. The reaction is quenched with water and the product is extracted into ethyl acetate. The combined organic phases are washed with saline, dried over sodium sulfate and concentrated under reduced pressure to give the title compound.

Provenance & Evidence