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

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Reaction Steps

In analogy with Example 1j), 3.2 g (7.12 mmol) of 5(S)-(Boc-amino)-4(S)-hydroxy-6-phenyl-2(R)-[(2,4-difluorophenyl)methyl]hexanoic acid in 67 ml of DMF are silylated with 4.93 g (32.7 mmol) of tert-butyldimethylchlorosilane and 3.97 g (58.4 mmol) of imidazole. Hydrolysis of the silyl ester function with 5.9 g of potassium carbonate in 77 ml of methanol, 20 ml of THF and 20 ml of water yields the title compound after column chromatography (SiO2, hexane/ethyl acetate, 2:1): TLC Rf (D)=0.22; tRet (II)=20.8 min.

Provenance & Evidence