Trifluoroacetic acid → (S)-4-[(S)-4-(3-Chloro-4-trifluoromethyl-phenyl)-3-methyl-2-oxo-piperazin-1-yl]-3-hydroxy-butyric acid methyl ester

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Reaction Conditions

Reaction Steps

1.82 g (3.9 mmol) of (S)-4-[[(S)-2-(3-chloro-4-trifluoromethyl-phenylamino)-propionyl]-(2,2-dimethoxy-ethyl)-amino]-3-hydroxy-butyric acid methyl ester were dissolved at RT in 39.0 ml of dichloromethane, cooled (0° C.) and treated with 4.4 ml of trifluoroacetic acid. After 30 min at 0° C. and 2.5 h at RT 3.2 ml (19.3 mmol) of triethylsilane were added and stirred over night at RT. The reaction was neutralized with 8.1 ml (58 mmol) of triethylamine at 0° C. and after 10 min poured on aqueous 10% KHSO4/EtOAc (3×). The organic phases were washed with aqueous 10% KHSO4, saturated NaHCO3, 10% NaCl and dried over Na2SO4 to yield after flash chromatography (SiO2, EtOAc/Heptan from 1:1 to 4:1) 0.114 g (7%) of the titled compound as yellow oil. MS: 409.2 (MH+).

Provenance & Evidence