Hydrochloric Acid → (S)-2-Amino-4-methyl-pentanoic acid [4,4-bis-(4-fluoro-phenyl)-butyl]-amide monohydrochloride

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Reaction Steps

To a solution of (S)-{1-[4,4-bis-(4-fluoro-phenyl)-butylcarbamoyl]-3-methyl-butyl}-carbamic acid tert-butyl ester (1.4 g, 3.8 mmol, Example 6) in CH2Cl2 (15 mL) was added trifluoroacetic acid (5 mL) at ambient temperature under nitrogen atmosphere. The resulting reaction mixture was stirred for 25 minutes, then concentrated in vacuo. The viscous oil obtained was dissolved in 60 mL of CH2Cl2 and successively washed with saturated aqueous NaHCO3 solution (2×60 mL), brine (2×60 mL), and was dried over Na2SO4. The CH2Cl2 solution of free amine was concentrated in vacuo to afford the crude product as a viscous oil which was then dissolved in 10 mL of ethyl ether. To this solution was added saturated HCl solution in ethyl ether until no more white precipitate formed. Filtration and drying overnight under vacuum afforded 1.2 g (99.6%) of crude product. A portion of the crude product, a HCl salt, was converted back to the free amine by treatment with saturated aqueous NaHCO3 solution; the crude free amine was further purified by flash chromatography (straight EtOAc, then 10% MeOH in HCCl3) and converted into HCl salt as described above. Pure titled compound was obtained as a white foam (0.3 g); mp 65-80° C. APCI-MS m/z 375.3 (MH+).

Provenance & Evidence