Water → 6-Hydroxy-chroman-4-one

HRID 1684616Notes

Reaction equation

HRID 1684616 reaction equation
C[O:2][C:3]1[CH:4]=[C:5]2[C:10](=[CH:11][CH:12]=1)[O:9][CH2:8][CH2:7][C:6]2=[O:13].O>Br.C(O)(=O)C>[OH:2][C:3]1[CH:4]=[C:5]2[C:10](=[CH:11][CH:12]=1)[O:9][CH2:8][CH2:7][C:6]2=[O:13]

Participants

5

Reactant 2

HCID 962WaterHCID 46121686-methoxy-3,4-dihydro-2H-1-benzopyran-4-one

Product 1

HCID 70989446-Hydroxy-chroman-4-oneYield 93.2%

Reagents, catalysts & solvents 2

HCID 176Acetic AcidSolventHCID 260Hydrogen BromideSolvent

Procedure

A mixture of 50.0 g (281 mmol) of 6-methoxychroman-4-one in 350 mL 48% HBr and 350 mL acetic acid was heated to reflux under N2. After 4 hours, the reaction mixture was cooled to room temperature in a Rotovap (trademark) and 1 L H2O was added. The suspension was kept at 0° C. overnight. The mixture was filtered, and the precipitate washed two times with H2O, two times with hexanes and then dried under vacuum to give 43.0 g of the title product as a dark purple/black solid. 93% yield.

Workup

  1. temperaturewas heated
  2. temperatureto reflux under N2
  3. additionwas added
  4. waitThe suspension was kept at 0° C. overnight
  5. filtrationThe mixture was filtered
  6. washthe precipitate washed two times with H2O, two times with hexanes
  7. customdried under vacuum

Sources & evidence

ORD record
ord-8f97ffc823af447a96235c135237dcb6
Source dataset
uspto-grants-1997_06
Patent number
US05641789

Reaction notes

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