Dimethyl Sulfoxide → N-[(1-Phenylindole-2-Carbonyl)Valinyl]-3-Amino-4-Oxo-5-Fluoropentanoic Acid, t-Butyl Ester

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Reaction Conditions

Reaction Steps

DMSO (0.13 mL, 1.9 mmol) was added to a methylene chloride solution of oxalyl chloride (0.29 mL, 2.0 M, 0.58 mmol in 4 mL of methylene chloride), and the resultant solution was stirred for 10 minutes under a nitrogen atmosphere at 78° C. A methylene chloride solution of N-[(1-phenylindole-2-carbonyl)valinyl]-3-amino-4-hydroxy-5-fluoropentanoic acid, t-butyl ester (200 mg, 0.38 mmol in 2 mL of dry methylene chloride) was added dropwise and resulting mixture stirred for 15 minutes at −78° C. Triethylamine (0.30 mL, 2.1 mmol) was added dropwise to the mixture, and the resultant mixture was stirred for 10 minutes at −78° C., then was allowed to warm to room temperature. The reaction mixture was partitioned between ethyl acetate and 5% KHSO4 solution and the aqueous layer was back-extracted with ethyl acetate. The combined ethyl acetate solutions were washed with 5% KHSO4 solution and brine, dried over sodium sulfate, and concentrated to give a crude product. The crude product was triturated to yield the title product as a slightly yellow powder (181 mg). TLC (ethyl acetate/hexanes 1:1): Rf=0.43.

Provenance & Evidence