Triisopropyl borate → B-[2,5-Dimethoxy-4-(phenylmethoxy)phenyl]boronic acid

HRID 444626Notes

Reaction equation

HRID 444626 reaction equation
[CH2:1]([O:8][C:9]1[CH:14]=[C:13]([O:15][CH3:16])[C:12](Br)=[CH:11][C:10]=1[O:18][CH3:19])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[B:20](OC(C)C)([O:25]C(C)C)[O:21]C(C)C>>[CH2:1]([O:8][C:9]1[C:10]([O:18][CH3:19])=[CH:11][C:12]([B:20]([OH:25])[OH:21])=[C:13]([O:15][CH3:16])[CH:14]=1)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1

Participants

3

Reactant 2

HCID 21531Triisopropyl borateHCID 110455271-Benzyloxy-4-bromo-2,5-dimethoxybenzene

Product 1

HCID 10935085B-[2,5-Dimethoxy-4-(phenylmethoxy)phenyl]boronic acidYield 62%

Conditions

Temperature
-78 °C

Procedure

1-Benzyloxy-4-bromo-2,5-dimethoxybenzene 4 (7.48 g,23.0 mmol) was placed in a dry flask and flushed with Ar. Dry THF (75 mL) was added and the solution was cooled to −78° C. in a dry ice/acetone bath. nBuLi (11 mL, 2.5M in hexanes) was added and the mixture was stirred for 20 min at −78° C. Triisopropyl borate (10.7 mL, 0.463 mol) was added and the reaction stirred for 2 h at −78° C. then allowed to come to room temperature at which time a white precipitate began to form. After stirring for an additional 20 h the reaction was quenched with saturated NH4Cl (25 mL). After separating the organic layer the aqueous layer was extracted with ethyl acetate (2×50 mL). The organic layers were combined, dried and concentrated. The residue was triturated with hexanes and filtered to give 4.1 g (62%) of 5b as a light off-white creamy solid. 1H-NMR (400 MHz, DMSO-d6) dH 3.70 (3H, s, OCH3), 3.79 (3H, s, OCH3), 5.16 (2H, s, CH2Ph), 6.77 (1H, s, ArH), 7.18 (1H, s, ArH), 7.33-7.52 (5H, m, CH2Ph)

Workup

  1. customflushed with Ar
  2. additionDry THF (75 mL) was added
  3. additionnBuLi (11 mL, 2.5M in hexanes) was added
  4. stirringthe reaction stirred for 2 h at −78° C.
  5. customto come to room temperature at which time
  6. customto form
  7. stirringAfter stirring for an additional 20 h the reaction
  8. customwas quenched with saturated NH4Cl (25 mL)
  9. customAfter separating the organic layer the aqueous layer
  10. extractionwas extracted with ethyl acetate (2×50 mL)
  11. customdried
  12. concentrationconcentrated
  13. customThe residue was triturated with hexanes
  14. filtrationfiltered

Sources & evidence

ORD record
ord-4e2f277e326d45b684d80df7e2991cea
Source dataset
uspto-grants-2013_07
Patent number
US08475776B2

Reaction notes

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