Trimethyl borate → (4-Fluoro-2-methylphenyl)boronic acid

HRID 650551Notes

Reaction equation

HRID 650551 reaction equation
Br[C:2]1[CH:7]=[CH:6][C:5]([F:8])=[CH:4][C:3]=1[CH3:9].C([Li])CCC.C[O:16][B:17](OC)[O:18]C.[OH-].[Na+]>O1CCCC1>[CH3:9][C:3]1[CH:4]=[C:5]([F:8])[CH:6]=[CH:7][C:2]=1[B:17]([OH:18])[OH:16]

Participants

6

Reactant 4

HCID 8470Trimethyl borateHCID 14798Sodium HydroxideHCID 967432-Bromo-5-fluorotolueneHCID 178418339Butyllithium

Product 1

HCID 2734665(4-Fluoro-2-methylphenyl)boronic acidYield 81%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

2-Bromo-5-fluorotoluene (52.9 mmol, 10 g) in 400 ml of tetrahydrofuran was cooled to −78° C. and n-butyllithium (2.5 M, 58.2 mmol) was added. The solution was stirred for 20 minutes, trimethoxy borane (3 eq, 0.16 mol) was added, and the reaction was allowed to warm to room temperature overnight. Sodium hydroxide (60 ml of 1.25 M) was added and the reaction was stirred for 30 minutes. The tetrahydrofuran was removed in vacuo. The remaining aqueous layer was diluted and extracted with diethyl ether The aqueous layer was adjusted to pH 3 with 2N HCl and extracted with ethyl acetate, which was dried (MgSO4) and concentrated in vacuo to give 6.57 g (81%) of a colorless solid: MS(FAB) m/e (rel. intensity) 154(48), 136(100).

Workup

  1. stirringthe reaction was stirred for 30 minutes
  2. customThe tetrahydrofuran was removed in vacuo
  3. additionThe remaining aqueous layer was diluted
  4. extractionextracted with diethyl ether The aqueous layer
  5. extractionextracted with ethyl acetate, which
  6. dry with materialwas dried (MgSO4)
  7. concentrationconcentrated in vacuo

Sources & evidence

ORD record
ord-b4f011098a274c8291646216e8319f3e
Source dataset
uspto-grants-2001_08
Patent number
US06274590B1

Reaction notes

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