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

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Reaction Steps

3.0 g of methyl (S)-2-benzyloxycarbonylamino-4,4-difluoro-5-phenylpentanoate (8.0 mmol) were admixed with 8.0 ml (5 eq.) of a 30% HBr solution in glacial acetic acid with ice bath cooling and stirred for 3 h. 100 ml of diethyl ether were added and the resulting precipitate was filtered off with suction. The crude product thus obtained was purified by preparative HPLC (gradient: acetonitrile/water and addition of 0.05% TFA). The amorphous solid obtained after freeze-drying was taken up in dichloromethane and washed with sat. NaHCO3 solution. The organic phase was dried over MgSO4 and concentrated under reduced pressure. Thus, methyl (S)-2-amino-4,4-difluoro-5-phenyl-pentanoate was obtained as a yellow oil.

Provenance & Evidence