Cesium carbonate → 2-methyl-1-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazol-1-yl]propan-2-ol

HRID 2366904Notes

Reaction equation

[CH3:1][C:2]1([CH3:14])[C:6]([CH3:8])([CH3:7])[O:5][B:4]([C:9]2[CH:10]=[N:11][NH:12][CH:13]=2)[O:3]1.C(=O)([O-])[O-].[Cs+].[Cs+].[CH3:21][C:22]1([CH3:25])[CH2:24][O:23]1>CN(C)C=O>[CH3:21][C:22]([OH:23])([CH3:25])[CH2:24][N:12]1[CH:13]=[C:9]([B:4]2[O:5][C:6]([CH3:7])([CH3:8])[C:2]([CH3:14])([CH3:1])[O:3]2)[CH:10]=[N:11]1

Participants

Conditions

Temperature: 110 °C

Procedure

To a solution of 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole (1.5 g, 7.73 mmol) and cesium carbonate (3.78 g, 11.60 mmol) in N,N-dimethylformamide (DMF) (17 mL) was added 2,2-dimethyloxirane (1.717 mL, 19.33 mmol) and the resulting mixture was stirred at 110° C. for 1 h under microwave irradiation then cooled to room temperature and filtered through celite (50 g). The insoluble material was washed with EtOAc (20 mL) and MeOH (20 mL). The combined filtrate and washings were concentrated in vacuo. Purification of the residue by flash chromatography using a 50 G silica cartridge (gradient: 0 to 100% (20% MeOH in DCM) in DCM) gave 2-methyl-1-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazol-1-yl]-2-propanol (2.10 g, 7.89 mmol, 102% yield) as a cream solid which was used in the next step without further purification.

Workup

temperaturethen cooled to room temperature
filtrationfiltered through celite (50 g)
washThe insoluble material was washed with EtOAc (20 mL) and MeOH (20 mL)
concentrationThe combined filtrate and washings were concentrated in vacuo
customPurification of the residue by flash chromatography

Sources & evidence

ORD record: ord-d72c8b8429ee4ac2834e90bbc9623c0f
Source dataset: uspto-grants-2014_04
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08697725B2

Reaction notes

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