Iodobenzene → 3,4-dihydro-2,5,7,8-tetramethyl-2-(2-phenylethynyl)-2H-1-benzopyran-6-ol

HRID 2050954Notes

Reaction equation

HRID 2050954 reaction equation
[C:1]([C:3]1([CH3:17])[CH2:8][CH2:7][C:6]2[C:9]([CH3:16])=[C:10]([OH:15])[C:11]([CH3:14])=[C:12]([CH3:13])[C:5]=2[O:4]1)#[CH:2].I[C:19]1[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1>>[CH3:17][C:3]1([C:1]#[C:2][C:19]2[CH:24]=[CH:23][CH:22]=[CH:21][CH:20]=2)[CH2:8][CH2:7][C:6]2[C:9]([CH3:16])=[C:10]([OH:15])[C:11]([CH3:14])=[C:12]([CH3:13])[C:5]=2[O:4]1

Participants

4

Reactant 3

HCID 11575IodobenzeneHCID 11776TriphenylphosphineHCID 14478563rac-3,4-dihydro-2-ethynyl-2,5,7,8-tetramethyl-2H-1-benzopyran-6ol

Product 1

HCID 151718093,4-dihydro-2,5,7,8-tetramethyl-2-(2-phenylethynyl)-2H-1-benzopyran-6-olYield 68.5%

Procedure

A mixture of 2.3 g (10 mmol) of rac-3,4-dihydro-2-ethynyl-2,5,7,8-tetramethyl-2H-1-benzopyran-6ol, 3.06 g (15 mmol) of iodobenzene, 0.39 g of triphenylphosphine. 95 mg of cuprous iodide 3 ml of triethylamine and 100 ml of acetonitrile was degassed with argon for 10 minutes. palladium acetate. 110 mg (0.5 mmol), was then added and stirring under argon was continued for 3 hours. The reaction mixture was evaporated under reduced pressure and the residue was partitioned between methylene chloride and saturated aqueous sodium bicarbonate solution. The organic phase was separated, dried over sodium sulfate and evaporated. The crude product was chromatographed over 100 g of silica gel (Merck 70-230 mesh) using methylene chloride for elution. The clean fractions were combined and evaporated and the residue was crystallized from hexane to yield 2.1 g (68 %) of rac-3,4-dihydro-2,5,7,8-tetramethyl-2-(phenylethynyl)-2H-1-benzopyran-6-ol with m.p. 109-111° C. The analytical sample was recrystallized from hexane and had m.p. 111°-113° C. Anal. Calcd. for C21H22O2 : C, 82.32; H, 7.24 Found ; C, 82.02; H, 7.30

Workup

  1. custom95 mg of cuprous iodide 3 ml of triethylamine and 100 ml of acetonitrile was degassed with argon for 10 minutes
  2. addition110 mg (0.5 mmol), was then added
  3. customThe reaction mixture was evaporated under reduced pressure
  4. customthe residue was partitioned between methylene chloride and saturated aqueous sodium bicarbonate solution
  5. customThe organic phase was separated
  6. dry with materialdried over sodium sulfate
  7. customevaporated
  8. customThe crude product was chromatographed over 100 g of silica gel (Merck 70-230 mesh)
  9. washfor elution
  10. customevaporated
  11. customthe residue was crystallized from hexane

Sources & evidence

ORD record
ord-9444b59d730a4b119daa293ce945d655
Source dataset
uspto-grants-1991_05
Patent number
US05015661

Reaction notes

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