1H-Pyrazole, 1-methyl- → 5-(5,5-Dimethyl-1,3,2-dioxaborinan-2-YL)-1-methyl-1H-pyrazole

HRID 1960979Notes

Reaction equation

HRID 1960979 reaction equation
[CH3:1][N:2]1[CH:6]=[CH:5][CH:4]=[N:3]1.[Li]CCCC.[CH:12]([O:15][B:16]1[O:20][C:19](C)(C)[C:18]([CH3:24])([CH3:23])O1)(C)C>C1COCC1.[NH4+].[Cl-]>[CH3:24][C:18]1([CH3:23])[CH2:12][O:15][B:16]([C:6]2[N:2]([CH3:1])[N:3]=[CH:4][CH:5]=2)[O:20][CH2:19]1

Participants

6

Reactant 3

HCID 702551H-Pyrazole, 1-methyl-HCID 50177412-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolaneHCID 178418339Butyllithium

Product 1

HCID 441194445-(5,5-Dimethyl-1,3,2-dioxaborinan-2-YL)-1-methyl-1H-pyrazoleYield 82.5%

Reagents, catalysts & solvents 2

HCID 8028TetrahydrofuranSolventHCID 25517Ammonium ChlorideSolvent

Procedure

To a solution of 1-methylpyrazole (4.1 g, 50 mmole) in THF (100 mL) at 0° C. was added n-BuLi (2.2M in THF, 55 mmole). The reaction solution was stirred for 1 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 (12.3 mL, 60 mmole). After 15 min at −78° C., the reaction was allowed to warm to 0° C. over 1 hour. The reaction was diluted with saturated NH4Cl solution and extracted with DCM. The organic fractions were washed with H2O (2×100 mL), dried over Na2SO4 and concentrated under vacuum to afford a tan solid (8.0 g, 77%) which was used without further purification. LCMS (ES) m/z 127 (M+H)+ for [RB(OH)2]; 1H NMR (CDCl3, 400 MHz) δ 7.57 (s, 1H), 6.75 (s, 1H), 4.16 (s, 3H), and 1.41 (s, 12H).

Workup

  1. waitAfter 15 min at −78° C.
  2. temperatureto warm to 0° C. over 1 hour
  3. extractionextracted with DCM
  4. washThe organic fractions were washed with H2O (2×100 mL)
  5. dry with materialdried over Na2SO4
  6. concentrationconcentrated under vacuum

Sources & evidence

ORD record
ord-94698c386fee484a8f8387f4e3c37fba
Source dataset
uspto-grants-2013_04
Patent number
US08410158B2

Reaction notes

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