Ammonium Chloride → (3-Bromo-6-ethoxy-pyrazolo[5,1-b][1,3]thiazol-7-yl)-carbamic acid tert-butyl ester

HRID 41264

Reaction equation

[C:1]([O:5][C:6](=[O:19])[NH:7][C:8]1[C:9]([O:16][CH2:17][CH3:18])=[N:10][N:11]2[CH:15]=[CH:14][S:13][C:12]=12)([CH3:4])([CH3:3])[CH3:2].C([Li])CCC.[Br:25]C(F)(F)C(F)(F)Br.[Cl-].[NH4+]>C(O)(=O)C.CCCCCC.C1COCC1>[C:1]([O:5][C:6](=[O:19])[NH:7][C:8]1[C:9]([O:16][CH2:17][CH3:18])=[N:10][N:11]2[C:15]([Br:25])=[CH:14][S:13][C:12]=12)([CH3:4])([CH3:3])[CH3:2]

Participants

Conditions

Temperature: -78 °C

Procedure

To a THF (150 mL) solution of (6-ethoxy-pyrazolo[5,1-b][1,3]thiazol-7-yl)-carbamic acid tert-butyl ester (16.5 g, 61.4 mmol), was added a 2.77M n-hexane solution of n-butyllithium (15.9 mL, 44 mmol) while stirring at −78° C. The mixture was stirred at −78° C. for one hour, and then 1,2-dibromotetrafluoroethane (2.61 mL, 22 mmol) was added, and the mixture was stirred while heating to room temperature for three hours. A saturated aqueous solution of ammonium chloride was added and acetic acid was added, and the mixture was extracted with ethyl acetate and washed with brine, dried over magnesium sulfate, and the solvent was distilled off under reduced pressure. The residue was purified by medium pressure silica gel column chromatography (n-heptane/ethyl acetate: 0% then 30%) to obtain 4.95 g (13.7 mmol) of the title compound.

Workup

stirringThe mixture was stirred at −78° C. for one hour
stirringthe mixture was stirred
temperaturewhile heating to room temperature for three hours
extractionthe mixture was extracted with ethyl acetate
washwashed with brine
dry with materialdried over magnesium sulfate
distillationthe solvent was distilled off under reduced pressure
customThe residue was purified by medium pressure silica gel column chromatography (n-heptane/ethyl acetate

Sources & evidence

ORD record: ord-c2d2587d7b5144dd95599b8e24411f34
Source dataset: uspto-grants-2013_09
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08530504B2

Linked notes

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