Selectfluor → 5-tert-Butyl-4-fluoro-2-methyl-2H-pyrazole-3-carboxylic acid ethyl ester

HRID 570188

Reaction equation

[CH2:1]([O:3][C:4]([C:6]1[N:7]([CH3:15])[N:8]=[C:9]([C:11]([CH3:14])([CH3:13])[CH3:12])[CH:10]=1)=[O:5])[CH3:2].[B-](F)(F)(F)[F:17].[B-](F)(F)(F)F.C1[N+]2(CCl)CC[N+](F)(CC2)C1>C(#N)C.CCOC(C)=O>[CH2:1]([O:3][C:4]([C:6]1[N:7]([CH3:15])[N:8]=[C:9]([C:11]([CH3:14])([CH3:13])[CH3:12])[C:10]=1[F:17])=[O:5])[CH3:2]

Participants

Conditions

Temperature: 80 °C

Procedure

5-tert-Butyl-2-methyl-2H-pyrazole-3-carboxylic acid ethyl ester (210 mg, 1.00 mmol) was added dropwise to a stirred solution of SELECTFLUOR® (531 mg, 1.50 mmol) in anhydrous acetonitrile (4 mL) under an Ar atmosphere. The resulting mixture was then stirred at 80° C. for 12 h, then cooled to room temperature, diluted with EtOAc (2 mL), and filtered. The solvent was removed under reduced pressure and the resulting residue was chromatographed on a 24-g SiO2 pre-packed column eluting with 0:1-1:4 EtOAc/hexanes to yield 5-tert-Butyl-4-fluoro-2-methyl-2H-pyrazole-3-carboxylic acid ethyl ester. 1H-NMR H-NMR (400 MHz, CDCl3) δ: 4.37 (q, J=7.2 Hz, 2H), 4.03 (d, J=1.0 Hz, 3H), 1.39 (t, J=7.1 Hz, 3H), 1.34 (s, 9H).

Workup

temperaturecooled to room temperature
filtrationfiltered
customThe solvent was removed under reduced pressure
customthe resulting residue was chromatographed on a 24-g SiO2 pre-packed column
washeluting with 0:1-1:4 EtOAc/hexanes

Sources & evidence

ORD record: ord-9cc8eb99829f4846a1aa9318e1fa345f
Source dataset: uspto-grants-2015_05
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US09023846B2

Linked notes

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