Tributyl borate → 2-(3-Boronophenyl)-2-methylpropanoic acid

HRID 1988567Notes

Reaction equation

HRID 1988567 reaction equation
Br[C:2]1[CH:3]=[C:4]([C:8]([CH3:13])([CH3:12])[C:9]([OH:11])=[O:10])[CH:5]=[CH:6][CH:7]=1.C([Li])(C)(C)C.[B:19](OCCCC)([O:25]CCCC)[O:20]CCCC>CCOCC>[C:9]([C:8]([C:4]1[CH:3]=[C:2]([B:19]([OH:25])[OH:20])[CH:7]=[CH:6][CH:5]=1)([CH3:13])[CH3:12])([OH:11])=[O:10]

Participants

5

Reactant 3

HCID 12712Tributyl borateHCID 128051282-(3-Bromophenyl)-2-methylpropanoic acidHCID 178418306HCID 178418306, compound

Product 1

HCID 442489972-(3-Boronophenyl)-2-methylpropanoic acid

Reagents, catalysts & solvents 1

HCID 3283Diethyl EtherSolvent2×

Procedure

To a solution of 2-(3-bromo-phenyl)-2-methyl-propionic acid (2.18 mmol) in anhydrous ether (20 mL) is added tert-butyl lithium (1.7 M in pentane, 5.4 mL, 9.16 mmol) dropwise at −78° C. and this mixture is stirred for 30 minutes treated with tributyl borate (2.34 mL, 8.72 mmol). The reaction mixture is allowed to warm up to room temperature, stirred for 15 hours, diluted with ether, and quenched with 1 M H3PO4. After stirring for 30 minutes the ether layer is separated and extracted three times with 2 N NaOH (20 mL). The combined NaOH extracts are acidified with 6 N HCl to pH=1 and extracted three times with ether (50 mL). The combined organic extracts are washed with brine, dried over sodium sulfate and concentrated to afford 3-(1-carboxy-1-methyl-ethyl)-phenyl boronic acid, which is used without further purification. MS: 209 (M+H).

Workup

  1. stirringstirred for 15 hours
  2. customquenched with 1 M H3PO4
  3. stirringAfter stirring for 30 minutes the ether layer
  4. customis separated
  5. extractionextracted three times with 2 N NaOH (20 mL)
  6. extractionextracted three times with ether (50 mL)
  7. washThe combined organic extracts are washed with brine
  8. dry with materialdried over sodium sulfate
  9. concentrationconcentrated

Sources & evidence

ORD record
ord-d83a479d931b44c9994db31b4cffc32f
Source dataset
uspto-grants-2010_01
Patent number
US07642249B2

Reaction notes

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