Imidazole → 5(S)-(Boc-Amino)-4(S)-(tert-butyldimethylsilyloxy)-6-(p-benzyloxy-phenyl)-2(R)-[(p-benzyloxyphenyl)methyl]hexanoic acid

Participants

Reaction Steps

Analogously to Example 1j), 2.44 g (3.90 mmol) of 5(S)-(Boc-amino)-4(S)-hydroxy-6-(p-benzyloxyphenyl)-2(R)-(p-benzyloxyphenylmethyl)-hexanoic acid in 14 ml of DMF are silylated with 2.70 g (17.6 mmol) of tert-butyldimethylchlorosilane and 2.18 g (32 mmol) of imidazole. Hydrolysis of the silyl ester function with 3.2 g of potassium carbonate in 90 ml of methanol/THF/water 3:1:1 and column chromatography (SiO2, hexane/ethyl acetate 2:1→1:1) of the crude product yields the title compound: TLC Rf (A)=0.53; FAB-MS (M+H)+ =740.

Provenance & Evidence