Triphosgene → (2R,4S)-5-biphenyl-4-yl-4-isocyanato-2-methyl-pentanoic acid benzyl ester

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Reaction Steps

To a vigorously stirred 1:1 mixture of methylene chloride/8% aqueous NaHCO3 (6 mL) at 0° C. is added triphosgene (18 mg, 0.061 mmol). After stirring the mixture at 0° C. for 5 minutes, (2R,4S)-4-amino-5-biphenyl-4-yl-2-methyl-pentanoic acid benzyl ester hydrochloride (Intermediate 30: 75 mg, 0.183 mmol) is added and stirring is continued for 15 minutes. The organic phase is separated and dried over sodium sulfate. The solvent is removed under reduced pressure to furnish (2R,4S)-5-biphenyl-4-yl-4-isocyanato-2-methyl-pentanoic acid benzyl ester.

Provenance & Evidence