Lithium borohydride → 3,8-dibromo-6H-benzo[c]chromene

HRID 71904Notes

Reaction equation

HRID 71904 reaction equation
[Br:1][C:2]1[CH:11]=[C:10]2[C:5]([C:6]3[CH:16]=[CH:15][C:14]([Br:17])=[CH:13][C:7]=3[C:8](=O)[O:9]2)=[CH:4][CH:3]=1.[Li+].[BH4-]>C1COCC1>[Br:1][C:2]1[CH:11]=[C:10]2[C:5]([C:6]3[CH:16]=[CH:15][C:14]([Br:17])=[CH:13][C:7]=3[CH2:8][O:9]2)=[CH:4][CH:3]=1

Participants

4

Reactant 2

HCID 4148881Lithium borohydrideHCID 595610423,8-Dibromo-benzo[c]chromen-6-one

Product 1

HCID 596107563,8-dibromo-6H-benzo[c]chromeneYield 86%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent2×

Procedure

To a solution of 3,8-dibromo-benzo[c]chromen-6-one (650 mg, 1.85 mmol) in THF (20 mL) was added 2 M solution of LiBH4 in THF (3.7 mL, 7.4 mmol). The mixture was stirred for 3 hours at room temperature. Quenched slowly with ammonium chloride solution. The mixture was extracted with ethyl acetate, dried over Na2SO4, filtered and concentrated in vacuo. The obtained residue was suspended in 85% phosphoric acid (20 mL) and heated at 160° C. for 4 h. The mixture was extracted with ethyl acetate, washed with water, dried over Na2SO4, filtered and concentrated in vacuo. The obtained residue was purified by flash chromatography to provide the desired product 3,8-Dibromo-6H-benzo[c]chromene as a white solid (539 mg, 86%).

Workup

  1. customQuenched slowly with ammonium chloride solution
  2. extractionThe mixture was extracted with ethyl acetate
  3. dry with materialdried over Na2SO4
  4. filtrationfiltered
  5. concentrationconcentrated in vacuo
  6. temperatureheated at 160° C. for 4 h
  7. extractionThe mixture was extracted with ethyl acetate
  8. washwashed with water
  9. dry with materialdried over Na2SO4
  10. filtrationfiltered
  11. concentrationconcentrated in vacuo
  12. customThe obtained residue was purified by flash chromatography

Sources & evidence

ORD record
ord-3d6b5ab642d548dab41de0064e307aae
Source dataset
uspto-grants-2014_09
Patent number
US08822430B2

Reaction notes

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