Sulfuric Acid → (2,5-Dimethylphenyl)boronic acid

HRID 990169Notes

Reaction equation

HRID 990169 reaction equation
[Mg].Br[C:3]1[CH:8]=[C:7]([CH3:9])[CH:6]=[CH:5][C:4]=1[CH3:10].[B:11](OC)([O:14]C)[O:12]C.S(=O)(=O)(O)O>C1COCC1>[CH3:10][C:4]1[CH:5]=[CH:6][C:7]([CH3:9])=[CH:8][C:3]=1[B:11]([OH:14])[OH:12]

Participants

6

Reactant 4

HCID 1118Sulfuric AcidHCID 8470Trimethyl borateHCID 11121Benzene, 2-bromo-1,4-dimethyl-HCID 5462224Magnesium

Product 1

HCID 2734347(2,5-Dimethylphenyl)boronic acid

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Procedure

Magnesium turnings (30.3 g; 0.55 mol) are placed ina baked-out apparatus flushed with argon, covered with about 30 ml of THF and treated with a few crystals of iodine. A few drops of bromo-p-xylene (cf. Example A1 a)) were subsequently added to the static solution. The Grignard reaction commenced very quickly and the remaining bromo-p-xylene (total amount: 92.5 g; about 70 ml; 0.5 mol) was subsequently added dropwise while stirring. The mixture was refluxed for 4 hours, then cooled. The Grignard solution was then transferred in a countercurrent of protective gas into a 500 ml dropping funnel and added dropwise at −70° C. to a solution of trimethyl borate (62.4 g; 67 ml; 0.6 mol) in 350 ml of THF while stirring (time: about 1 hour). During this addition, a precipitate was formed. The reaction mixture was allowed to warm to RT overnight and was then poured while stirring into a mixture of 700 g of ice and 20 ml of concentrated sulfuric acid. The organic phase was separated off, the aqueous phase was extracted three times with chloroform and the combined organic phases were evaporated. The crude product was recrystallized from chloroform/hexane.

Workup

  1. customflushed with argon
  2. additiontreated with a few crystals of iodine
  3. additionExample A1 a)) were subsequently added to the static solution
  4. customThe Grignard reaction
  5. temperatureThe mixture was refluxed for 4 hours
  6. temperaturecooled
  7. stirringwhile stirring (time: about 1 hour)
  8. additionDuring this addition
  9. customa precipitate was formed
  10. additionwas then poured
  11. customThe organic phase was separated off
  12. extractionthe aqueous phase was extracted three times with chloroform
  13. customthe combined organic phases were evaporated
  14. customThe crude product was recrystallized from chloroform/hexane

Sources & evidence

ORD record
ord-a6a85309d2af4c08962193b1e2b01376
Source dataset
uspto-grants-2002_10
Patent number
US06458909B1

Reaction notes

Loading…