Boron tribromide → 4,6-Dihydroxy-2H-1-benzopyran-2-one

HRID 897265Notes

Reaction equation

HRID 897265 reaction equation
[OH:1][C:2]1[C:11]2[C:6](=[CH:7][CH:8]=[C:9]([O:12]C)[CH:10]=2)[O:5][C:4](=[O:14])[CH:3]=1.B(Br)(Br)Br>C(Cl)Cl>[OH:1][C:2]1[C:11]2[C:6](=[CH:7][CH:8]=[C:9]([OH:12])[CH:10]=2)[O:5][C:4](=[O:14])[CH:3]=1

Participants

4

Reactant 2

HCID 25134Boron tribromideHCID 546765304-Hydroxy-6-methoxy-2H-1-benzopyran-2-one

Product 1

HCID 546791754,6-Dihydroxy-2H-1-benzopyran-2-oneYield 75.9%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Conditions

Temperature
-78 °C

Procedure

4-Hydroxy-6-methoxy-chromen-2-one (500 mg, 2.588 mmol) was suspended in CH2Cl2 (10 mL) and cooled to −78° C. under nitrogen. BBr3 (1 M solution in CH2Cl2, 13 mL, 13 mmol) was added to this suspension dropwise. Following completion of the addition, the resulting suspension was stirred at 25° C. for 1 h before being quenched by the slow addition of H2O. The product was extracted with EtOAc and the combined organic layers dried over Na2SO4 and concentrated to give 350 mg (75%) of the title compound as a tan solid. MS (ESI(+)Q1MS) m/z 179 (M+H)+; 1H NMR (300 MHz, DMSO) δ ppm 9.71 (bs, 1H), 7.01-7.23 (m, 3H), 5.57 (s, 1H).

Workup

  1. additioncompletion of the addition
  2. custombefore being quenched by the slow addition of H2O
  3. extractionThe product was extracted with EtOAc
  4. dry with materialthe combined organic layers dried over Na2SO4
  5. concentrationconcentrated

Sources & evidence

ORD record
ord-ba277070edb54d3881158f4b1a68b919
Source dataset
uspto-grants-2005_07
Patent number
US06921821B2

Reaction notes

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