4-Bromotoluene → Tolylboronic acid

HRID 864461Notes

Reaction equation

HRID 864461 reaction equation
Br[C:2]1[CH:7]=[CH:6][C:5]([CH3:8])=[CH:4][CH:3]=1.[Mg].[B:10](OC)([O:13]C)[O:11]C>C1COCC1>[C:5]1([CH3:8])[CH:6]=[CH:7][C:2]([B:10]([OH:13])[OH:11])=[CH:3][CH:4]=1

Participants

5

Reactant 3

HCID 78054-BromotolueneHCID 8470Trimethyl borateHCID 5462224Magnesium

Product 1

HCID 79799Tolylboronic acid

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent2×

Conditions

Temperature
-78 °C

Procedure

Under nitrogen, a solution of 94.1 g (0.55 mol) of 4-bromotoluene in 400 mL of anhydrous THF was treated with 14.5 g (0.60 mol) of magnesium turnings. The reaction was stirred at reflux for 2 h, cooled to -78° C. treated with a solution of 156 mL (1.38 mol) of trimethyl borate in 475 mL of THF, stirred for 1 h, and allowed to warm to ambient temperature. The reaction mixture was concentrated in vacuo and partitioned between aqueous base and methylene chloride. The pH of the aqueous phase was adjusted to one with hydrochloric acid and extracted with methylene chloride. The organic phase was dried (MgSO4) and concentrated in vacuo to give 4-tolylboronic acid: NMR (CDCl3) δ2.45 (s, 3H), 7.31 (d, J=8 Hz, 2H), 8.13 (d, J=8 Hz, 2H).

Workup

  1. temperatureat reflux for 2 h
  2. stirringstirred for 1 h
  3. temperatureto warm to ambient temperature
  4. concentrationThe reaction mixture was concentrated in vacuo
  5. custompartitioned between aqueous base and methylene chloride
  6. extractionextracted with methylene chloride
  7. dry with materialThe organic phase was dried (MgSO4)
  8. concentrationconcentrated in vacuo

Sources & evidence

ORD record
ord-89f3f37afdb64fc49be298ac5eaa22e5
Source dataset
uspto-grants-1996_10
Patent number
US05563139

Reaction notes

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