Hydrochloric Acid → (1,2-diphenyl-1H-benzimidazol-5-yl)Boronic acid

HRID 1172778Notes

Reaction equation

HRID 1172778 reaction equation
Br[C:2]1[CH:22]=[CH:21][C:5]2[N:6]([C:15]3[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=3)[C:7]([C:9]3[CH:14]=[CH:13][CH:12]=[CH:11][CH:10]=3)=[N:8][C:4]=2[CH:3]=1.C([Li])CCC.C[O:29][B:30](OC)[O:31]C.Cl>C1COCC1>[C:15]1([N:6]2[C:5]3[CH:21]=[CH:22][C:2]([B:30]([OH:31])[OH:29])=[CH:3][C:4]=3[N:8]=[C:7]2[C:9]2[CH:14]=[CH:13][CH:12]=[CH:11][CH:10]=2)[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=1

Participants

6

Reactant 4

HCID 313Hydrochloric AcidHCID 8470Trimethyl borateHCID 230940595-bromo-1,2-diphenyl-1H-benzo[d]imidazoleHCID 178418339Butyllithium

Product 1

HCID 23160233(1,2-diphenyl-1H-benzimidazol-5-yl)Boronic acidYield 35.1%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent

Conditions

Temperature
-78 °C

Procedure

In an argon atmosphere, 10 g (29 mmol) of 5-bromo-1,2-diphenyl-1H-benzimidazole were dissolved into 100 mL of dehydrated THF, and the temperature of the solution was cooled to −78° C. Then, 20 mL of n-butyllithium (in hexane, 1.6 mol/L) were dropped. After the mixture had been stirred at −78° C. for 1 hour, the temperature of the mixture was increased to 0° C. The temperature of the mixture was cooled to −78° C. again, and 9.7 mL (87 mmol) of trimethoxyborane were dropped. The mixture was stirred at −78° C. for 1 hour, and was then stirred at room temperature for 2 hours. 100 mL of 10-mass % hydrochloric acid were added, and the whole was stirred for 1 hour, followed by filtration. The organic layer of the filtrate was washed with a saturated sodium chloride solution and dried with magnesium sulfate. The solvent was distilled off under reduced pressure, and the residue was purified by means of silica gel column chromatography to obtain 3.2 g of 1,2-diphenyl-1H-benzimidazole-5-boronic acid (35% yield).

Workup

  1. temperaturethe temperature of the mixture was increased to 0° C
  2. temperatureThe temperature of the mixture was cooled to −78° C. again
  3. stirringThe mixture was stirred at −78° C. for 1 hour
  4. stirringwas then stirred at room temperature for 2 hours
  5. stirringthe whole was stirred for 1 hour
  6. filtrationfollowed by filtration
  7. washThe organic layer of the filtrate was washed with a saturated sodium chloride solution
  8. dry with materialdried with magnesium sulfate
  9. distillationThe solvent was distilled off under reduced pressure
  10. customthe residue was purified by means of silica gel column chromatography

Sources & evidence

ORD record
ord-dc72c64157954013abaa0af8c288f3ca
Source dataset
uspto-grants-2010_11
Patent number
US07833632B2

Reaction notes

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