Trifluoroacetic acid → 4-[(R)-4-(3,4-Dichloro-phenyl)-3-methyl-2-oxo-piperazin-1-yl]-butyric acid

Participants

Reaction Conditions

Reaction Steps

0.69 ml (9.00 mmol) of trifluoroacetic acid was added to a cooled solution (0° C.) of 0.28 g (0.60 mmol) 4-[[(R)-2-(3,4-dichloro-phenylamino)-propionyl]-(2,2-dimethoxy-ethyl)-amino]-butyric acid tert-butyl ester (62% ee) in 6 ml of dichloromethane. After 30 min the ice bath was removed, then after 1 h, 0.49 ml (3.00 mmol) of triethylsilane was added. After 16 h the reaction mixture was cooled to 0° C. and treated with 1.25 ml (9.00 mmol) of triethylamine, then after 15 min partitioned between Et2O (3×)/aqueous 10% KHSO4, the organic phases were washed with aqueous 10% KHSO4 and aqueous 10% NaCl, dried over Na2SO4 and evaporated. The residue was precipitated (dichloromethane/n-pentane) to give 0.198 g (96%) of the titled compound as brown viscous oil. MS: 345.07 (MH+, 2Cl).

Provenance & Evidence