Trifluoroacetic acid → (S)-4-Benzyloxy-2-[4-(3,4-dichloro-phenyl)-3-methyl-7-oxo-[1,4]diazepan-1-yl]-butyric Acid methyl ester

Participants

Reaction Steps

A cooled solution (0° C.) of 1.75 g (3.23 mmol) of (S)-4-benzyloxy-2-[[2-(3,4-dichloro-phenylamino)-propyl]-(3,3-dimethoxy-propionyl)-amino]-butyric acid methyl ester in 30 ml CH2Cl2 was treated with 3.71 ml (48.48 mmol) of trifluoroacetic acid and after 2 h at RT with 2.57 ml (16.16 mmol) of triethylsilane. The reaction was stirred at RT for 16 h, cooled (0° C.) and neutralized with 6.76 ml (48.48 mmol) of triethylamine. The residue was dissolved in diethyl ether and cold water. The reaction was extracted with 10% aq. KHSO4 solution/diethyl ether (3×). The organic phases were washed with sat. aq. NaHCO3 solution, dried over Na2SO4 and evaporated. Flash silica gel column (n-heptane/EtOAc 4:1→1:1) afforded 0.79 g (46%) of the title compound as a 71:29 mixture of the (R) and (S) diastereomers. Orange oil, MS: 479.1 (MH+, 2Cl).

Provenance & Evidence