Trimethyl borate → (3-Benzyl-4-methoxyphenyl)boronic acid

HRID 971339Notes

Reaction equation

[Li]CCCC.[CH2:6]([C:13]1[CH:18]=[C:17](Br)[CH:16]=[CH:15][C:14]=1[O:20][CH3:21])[C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1.[B:22](OC)([O:25]C)[O:23]C.[OH-].[Na+]>C1COCC1.O>[CH2:6]([C:13]1[CH:18]=[C:17]([B:22]([OH:25])[OH:23])[CH:16]=[CH:15][C:14]=1[O:20][CH3:21])[C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1

Participants

Conditions

Temperature: -78 °C

Procedure

8.61 ml (13.8 mmol, 1 eqv) of a 1.6 M solution of n-BuLi in hexanes was added to a solution of 3.82 g (13.8 mmol) 2-Benzyl-4-bromo-anisol (21) in 100 ml dry THF at −78° C. After stirring this mixture for 30 min at −78° C., 4.70 ml (41.4 mmol, 3 eqv) B(OMe)3 was added and the solution was stirred for 24 h at rt. Now 10 ml water and 25 ml of a 10% aq. NaOH-solution were added and stirring was continued for further 60 min. Then the pH was adjusted to 4-5 with 1-N-HCl-solution and most of the solvent was evaporated. The residue was extracted with EtOAc and the comb. org. fractions were dried over MgSO4 and evaporated, which led after drying in high vacuum to 3.33 g (13.8 mmol, 100%) of an orange solid. This crude boronic acid 22 was used without further purification: 1H NMR (500 MHz, CDCl3) δ 3.81 (s, 3H), 3.98 (s, 2H), 6.89 (d, 1H, J=8.20 Hz), 7.10-7.23 (m, 5H), 7.79 (d, 1H, J=1.58 Hz), 7.96 (dd, 1H, J1=8.20 Hz, J2=1.73 Hz).

Workup

stirringthe solution was stirred for 24 h at rt
stirringstirring
waitwas continued for further 60 min
customwas evaporated
extractionThe residue was extracted with EtOAc
dry with materialfractions were dried over MgSO4
customevaporated
customThis crude boronic acid 22 was used without further purification

Sources & evidence

ORD record: ord-75f14d7f88c84589924fd56fd51d9824
Source dataset: uspto-grants-2007_12
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US07312246B2

Reaction notes

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