1,3-Dibromobenzene → (3-Bromophenyl)boronic acid

HRID 653618Notes

Reaction equation

HRID 653618 reaction equation
[Li+].CCC[CH2-].[Br:6][C:7]1[CH:12]=[CH:11][CH:10]=[C:9](Br)[CH:8]=1.C([O:17][B:18](OC(C)C)[O:19]C(C)C)(C)C.CCCCCC>CCOCC>[Br:6][C:7]1[CH:8]=[C:9]([B:18]([OH:19])[OH:17])[CH:10]=[CH:11][CH:12]=1

Participants

6

Reactant 4

HCID 79271,3-DibromobenzeneHCID 8058HexaneHCID 21531Triisopropyl borateHCID 61028n-Butyl lithium

Product 1

HCID 2734318(3-Bromophenyl)boronic acid

Reagents, catalysts & solvents 1

HCID 3283Diethyl EtherSolvent2×

Procedure

N-butyllithium (2.5M) (44 mL; 0.11M) was added dropwise over 15 mins. to a vigorously stirred solution of m-dibromobenzene (25G; 0.106M) in 500 mL of anhydrous ether at -78° under nitrogen. After stirring 10 mins. more, a solution of triisopropylborate (25.3 mL; 0.11M) in anhydrous ether (200 mL) was added over 20 mins. The cooling bath was then removed and the stirring solution was allowed to warm to R.T. over ~2 hrs. A small amount of solid separated. After stirring 15 mins. more at R.T., 150 mL of ice cold 8% aqueous hydrochloric acid was cautiously added, and the stirring was continued for 15 mins. The organic phase was separated, washed with 2×100 mL of a saturated sodium chloride solution, and dried over anhydrous magnesium sulfate. Solvent removal gave ~30 G of crude product as a semi-solid, which was shaken well with 150 mL of hexane. The solid was filtered and washed with 2×25 mL of hexane. The resulting silky solid (mp 178°-9° C. after softening at ~160° C.) (6.5 G) was used as 3-bromophenylboronic acid with a small amount of contamination. The hexane filtrate was concentrated and the residue was stirred well with 150 mL of petroleum ether (30°-60° C.). The resulting solid was filtered and washed with 2×25 mL of petroleum ether. This resulting solid (4.4G) melting at 178.3°-179° C. was the desired 3bromophenylboronic acid.

Workup

  1. customat -78°
  2. customThe cooling bath was then removed
  3. customA small amount of solid separated
  4. stirringAfter stirring 15 mins
  5. additionmore at R.T., 150 mL of ice cold 8% aqueous hydrochloric acid was cautiously added
  6. waitthe stirring was continued for 15 mins
  7. customThe organic phase was separated
  8. washwashed with 2×100 mL of a saturated sodium chloride solution
  9. dry with materialdried over anhydrous magnesium sulfate
  10. customSolvent removal
  11. customgave ~30 G of crude product as a semi-solid, which
  12. filtrationThe solid was filtered
  13. washwashed with 2×25 mL of hexane
  14. customThe resulting silky solid (mp 178°-9° C. after softening at ~160° C.) (6.5 G)
  15. concentrationThe hexane filtrate was concentrated
  16. stirringthe residue was stirred well with 150 mL of petroleum ether (30°-60° C.)
  17. filtrationThe resulting solid was filtered
  18. washwashed with 2×25 mL of petroleum ether

Sources & evidence

ORD record
ord-ad601846b2304cc9a63d632ebf00e453
Source dataset
uspto-grants-1992_07
Patent number
US05128335

Reaction notes

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