Tetrahydrofuran → 1,4-dimethyl-5-(tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole

HRID 2391960Notes

Reaction equation

HRID 2391960 reaction equation
C1COCC1.[CH3:6][N:7]1[CH:11]=[C:10]([CH3:12])[CH:9]=[N:8]1.[Li]CCCC.C(O[B:22]1[O:26][C:25]([CH3:28])([CH3:27])[C:24]([CH3:30])([CH3:29])[O:23]1)(C)C>[NH4+].[Cl-]>[CH3:6][N:7]1[C:11]([B:22]2[O:26][C:25]([CH3:28])([CH3:27])[C:24]([CH3:30])([CH3:29])[O:23]2)=[C:10]([CH3:12])[CH:9]=[N:8]1

Participants

6

Reactant 4

HCID 8028TetrahydrofuranHCID 1368361,4-DimethylpyrazoleHCID 50177412-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolaneHCID 178418339Butyllithium

Product 1

HCID 578266761,4-dimethyl-5-(tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazoleYield 78%

Reagents, catalysts & solvents 1

HCID 25517Ammonium ChlorideSolvent

Procedure

At 0° C., to above THF solution of 1,4-dimethylpyrazole was added n-BuLi (2.5M in hexane, 58.5 mL, 146 mmole). The reaction solution was stirred for 2 hour at RT and then cooled to −78° C. [J. Heterocyclic Chem. 41, 931 (2004)]. To the reaction solution was added 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (27.2 g, 146 mmole). After 15 min at −78° C., the reaction was allowed to warm to 0° C. and stir for 3 h. The reaction was diluted with saturated NH4Cl solution and extracted with DCM. The organics were dried over Na2SO4 and concentrated under vacuum to afford the title compound as a brown solid (21 g, 78%) which was used directly without further purification: LC-MS: 141 (M-C6H12)+, 223 (M+H)+. 1H NMR (CDCl3): δ 7.28 (s, 1H), 4.03 (s, 3H), 2.22 (s, 3H), and 1.32 (s, 12H).

Workup

  1. waitAfter 15 min at −78° C.
  2. temperatureto warm to 0° C.
  3. stirringstir for 3 h
  4. extractionextracted with DCM
  5. dry with materialThe organics were dried over Na2SO4
  6. concentrationconcentrated under vacuum

Sources & evidence

ORD record
ord-8db45cc30e154a17a8391d878249b6cc
Source dataset
uspto-grants-2012_09
Patent number
US08273782B2

Reaction notes

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