Water → 2-Tert-butoxycarbonylamino-4-hydroxy-butyric acid benzyl ester

HRID 226217Notes

Reaction equation

[BH4-].[Na+].O.O=C1CCC(=O)N1[O:11][C:12](=O)[CH2:13][CH:14]([NH:25][C:26]([O:28][C:29]([CH3:32])([CH3:31])[CH3:30])=[O:27])[C:15]([O:17][CH2:18][C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1)=[O:16]>C1COCC1>[CH2:18]([O:17][C:15](=[O:16])[CH:14]([NH:25][C:26]([O:28][C:29]([CH3:31])([CH3:30])[CH3:32])=[O:27])[CH2:13][CH2:12][OH:11])[C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1

Participants

Conditions

Temperature: 0 °C

Procedure

A solution of NaBH4 (262 mg, 6.92 mmol) in 4:1 THF:H2O (20 ml) was cooled to 0° C. To this mixture was slowly added a solution of the ester from step (38a) (4.61 mmol) in THF (12 ml). Gas was evolved. When gas evolution ceased, the mixture was quenched by the careful addition of saturated aqueous ammonium chloride. The resulting solution was stirred at 0° C. for an additional 15 min. EtOAc (200 ml) was added and the resulting mixture was washed with saturated aqueous NaCl. The organic layer was dried over MgSO4 and concentrated in vacuo. Purification by flash chromatography (silica, 0-10% MeOH/CHCl3) gave 2-tert-butoxycarbonylamino-4-hydroxy-butyric acid benzyl ester (350 mg, 25% for 2 steps) as a clear, colorless oil: 1H NMR (300 MHz, Methanol-D) δ 7.23-7.43 (m, 5 H), 5.06-5.25 (m, 2 H), 4.00-4.57 (m, 2 H), 3.54-3.69 (m, 1 H), 1.67-2.12 (m, 2 H), 1.29-1.50 (m, 9 H). LC-MS (Method A, retention time: 1.25 min).

Workup

customthe mixture was quenched by the careful addition of saturated aqueous ammonium chloride
additionEtOAc (200 ml) was added
washthe resulting mixture was washed with saturated aqueous NaCl
dry with materialThe organic layer was dried over MgSO4
concentrationconcentrated in vacuo
customPurification by flash chromatography (silica, 0-10% MeOH/CHCl3)

Sources & evidence

ORD record: ord-f7e733a1e8564ae5a70fdc53fae2e18d
Source dataset: uspto-grants-2009_07
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07557137B2

Reaction notes

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