Methanol → (4S)-1-[(2H-1,3-Benzodioxol-5-yl)methyl]-4-{(3,3-dimethylbutanoyl)[(3-methoxyphenyl)methyl]amino}-L-proline

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Reaction Steps

Lithium hydroxide monohydrate (17 mg, 0.405 mmol) was added to a solution of methyl(2S,4S)-1-(1,3-benzodioxol-5-ylmethyl)-4-[(3,3-dimethylbutanoyl)(3-methoxybenzyl)amino]tetrahydro-1H-2-pyrrolecarboxylate (20) (100 mg, 0.20 mmol) in 66% v/v methanol in water (1.0 mL). The mixture was stirred overnight at room temperature, then the solvent was removed under reduced pressure and the residue partitioned between dichloromethane (1.0 mL) and water (1.0 ml). The aqueous phase was acidified with 1.0 M aqueous citric acid solution and the two layers were vigorously stirred for 10 min at room temperature. The layers were separated and the aqueous layer was back-extracted with dichloromethane. The combined dichloromethane extracts were dried (MgSO4) and evaporated under reduced pressure. The residue was purified by flash column chromatography on silica gel using dichloromethane/ethyl acetate (1:1, v/v) and then dichloromethane/methanol (9:1, v/v) as eluents to give the title acid (21) (88 mg, 91%) as an off-white solid:

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