Methyl (S)-2-benzyloxycarbonylamino-4,4-difluoro-5-phenylpentanoate → Methyl (S)-2-amino-4,4-difluoro-5-phenylpentanoate

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Reaction Steps

In a three-neck flask, methyl (S)-2-benzyloxycarbonylamino-4,4-difluoro-5-phenylpentanoate (1.0 g, 2.65 mmol) was dissolved in 25 ml of methanol. After repeated evacuation and sparging with argon, 350 mg of Pd/C (10%) were added. After degassing and sparging with argon again, the argon atmosphere was replaced by hydrogen (balloon with H2 gas). The mixture was stirred at RT for 3 h. Owing to incomplete conversion, a further 350 mg of catalyst were added and the mixture was hydrogenated at RT for a further 5 h. On completion of conversion, the reaction mixture was filtered. The mixture was washed with 20 ml of methanol and the filtrate was concentrated by evaporation under reduced pressure. A waxy residue was obtained which, as well as the desired product, also contained smaller amounts of the monodefluorinated and didefluorinated product. This residue was used without further purification for the further reaction.

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