Bromobenzene → 2,2-Dimethyl-4-phenyl-2H-1-benzopyran-7-ol

HRID 614745Notes

Reaction equation

HRID 614745 reaction equation
Br[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[Mg].[CH3:9][C:10]1([CH3:22])[CH2:19][C:18](=O)[C:17]2[C:12](=[CH:13][C:14]([OH:21])=[CH:15][CH:16]=2)[O:11]1.[Cl-].[NH4+]>O1CCCC1>[CH3:9][C:10]1([CH3:22])[CH:19]=[C:18]([C:2]2[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=2)[C:17]2[C:12](=[CH:13][C:14]([OH:21])=[CH:15][CH:16]=2)[O:11]1

Participants

6

Reactant 4

HCID 7961BromobenzeneHCID 25517Ammonium ChlorideHCID 6009027-hydroxy-2,2-dimethyl-3,4-dihydro-2H-1-benzopyran-4-oneHCID 5462224Magnesium

Product 1

HCID 205704922,2-Dimethyl-4-phenyl-2H-1-benzopyran-7-olYield 57.4%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent2×

Procedure

Bromobenzene (141.3 g) in dry tethydrofuran (300 ml) was added to magnesium (23.7 g) in dry tetrahydrofuran (100 ml). 2,2-Dimethylchroman-4-one-7-ol (34.5 g) in dry tetrahydrofuran (250 ml) was then added and the solution refluxed for 48 hours. The mixture was poured into ammonium chloride solution, the tetrahydrofuran layer was separated and evaporated under reduced pressure. The aqueous layer was extracted with ethyl acetate and the organic layer and the residue from the tetrahydrofuran layer was shaken with 10% sodium hydroxide solution. The basic layer was acidified and re-extracted with ethyl acetate. The organic layers were dried (MgSO4). Removal of the solvent under reduced pressure gave an oil (26 g) which was chromatographed on silica. Elution with ether - petrol (1:1) gave the title compound (14 g).

Workup

  1. temperaturethe solution refluxed for 48 hours
  2. customthe tetrahydrofuran layer was separated
  3. customevaporated under reduced pressure
  4. extractionThe aqueous layer was extracted with ethyl acetate
  5. extractionre-extracted with ethyl acetate
  6. dry with materialThe organic layers were dried (MgSO4)
  7. customRemoval of the solvent under reduced pressure

Sources & evidence

ORD record
ord-6fc53cf9ad2b4086ac9eec1f67a6c205
Source dataset
uspto-grants-1979_03
Patent number
US04146539

Reaction notes

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