Diethyl Carbonate → 6,8-Dibromo-4-hydroxy-2H-1-benzopyran-2-one

HRID 495129Notes

Reaction equation

HRID 495129 reaction equation
[CH2:1]([O:3]C(=O)OCC)C.[H-].[Na+].[Br:11][C:12]1[C:13]([OH:22])=[C:14]([C:19](=[O:21])[CH3:20])[CH:15]=[C:16]([Br:18])[CH:17]=1.[OH-].[Na+]>C1(C)C=CC=CC=1>[Br:18][C:16]1[CH:17]=[C:12]([Br:11])[C:13]2[O:22][C:1](=[O:3])[CH:20]=[C:19]([OH:21])[C:14]=2[CH:15]=1

Participants

6

Reactant 4

HCID 7766Diethyl CarbonateHCID 14798Sodium HydroxideHCID 24758Sodium hydrideHCID 2717623',5'-Dibromo-2'-Hydroxyacetophenone

Product 1

HCID 547077896,8-Dibromo-4-hydroxy-2H-1-benzopyran-2-oneYield 18.4%

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent2×

Conditions

Temperature
105 °C

Procedure

A solution is prepared of diethylcarbonate (62.5 mmol, 7.6 mL) in 150 mL of toluene to which is added NaH (37.5 mmol, 1.5 g of 60% dispersion in mineral oil) in portions. To this solution is added, dropwise, 3′,5′-dibromo-2′-hydroxyacetophenone (12.5 mmol, 3.67 g) in 50 mL of toluene. The reaction is heated to 105° C. overnight, cooled to ambient temperature, 100 mL of 1N NaOH, is added and the reaction is stirred vigorously for 5 hrs at ambient temperature. The layers are separated and the aqueous layer is washed with EtOAc 2×. The combined organic layers are washed with H2O 1×. The combined aqueous layers are acidified to pH 2 with conc HCl to form a precipitate that is filtered and is washed with H2O. The solid material is dissolved in ACN/H2O and speed vacced to dryness to afford the title compound as a light tan solid (0.737 g, 18%). 1H NMR (DMSO-d6, 300 MHz) δ 12.98 (1H, br s), 8.18 (1H, d, J=2.25 Hz), 7.90 (1H, d, J=2.25 Hz), 5.64 (1H, s); MS (ESI, Pos.) calcd for C9H4Br2O3 m/z [M+H]=318.9, found 318.9.

Workup

  1. additionTo this solution is added
  2. temperaturecooled to ambient temperature
  3. customThe layers are separated
  4. washthe aqueous layer is washed with EtOAc 2×
  5. washThe combined organic layers are washed with H2O 1×
  6. customto form a precipitate that
  7. filtrationis filtered
  8. washis washed with H2O
  9. dissolutionThe solid material is dissolved in ACN/H2O

Sources & evidence

ORD record
ord-ec436f7b21b9422389f11fd23d2a2498
Source dataset
uspto-grants-2009_05
Patent number
US07538233B2

Reaction notes

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