Lithium Hydroxide → L-Proline, N-(methoxycarbonyl)-L-valyl-5-methyl-, (5S)-

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Reaction Steps

(2S,5S)-Ethyl 1-((S)-2-(methoxycarbonylamino)-3-methylbutanoyl)-5-methylpyrrolidine-2-carboxylate (39.3 mmol, assuming complete conversion from the previous transformation) was suspended in MeOH (200 mL) and aqueous LiOH (1.0 M, 100 mL, 100 mmol) was added. The reaction mixture was stirred o/n, then concentrated under reduced pressure to remove most of the MeOH. The aqueous solution was washed 2× with DCM before being acidified to pH-1-2 with 10% HCl. The acidic aqueous phase was then extracted 5× with EtOAc. The combined EtOAc extracts were dried over MgSO4 filtered and concentrated under reduced pressure to afford (2S,5S)-1-((S)-2-(Methoxycarbonylamino)-3-methylbutanoyl)-5-methylpyrrolidine-2-carboxylic acid (6.89 g, 56% over 2 steps).

Provenance & Evidence