Tetrahydrofuran → rac-3,4-dihydro-2,5,7,8-tetramethyl-2-(2-propenyl)-6-(phenylmethoxy)-2H-1-benzopyran

HRID 621742Notes

Reaction equation

HRID 621742 reaction equation
[CH2:1]([Mg]Cl)[CH:2]=C.Cl[C:7]1([CH3:28])[CH2:12][CH2:11][C:10]2[C:13]([CH3:27])=[C:14]([O:19][CH2:20][C:21]3[CH:26]=[CH:25][CH:24]=[CH:23][CH:22]=3)[C:15]([CH3:18])=[C:16]([CH3:17])[C:9]=2[O:8]1.O1CCC[CH2:30]1>CCOCC>[C:21]1([CH2:20][O:19][C:14]2[C:15]([CH3:18])=[C:16]([CH3:17])[C:9]3[O:8][C:7]([CH2:28][CH:1]=[CH2:2])([CH3:30])[CH2:12][CH2:11][C:10]=3[C:13]=2[CH3:27])[CH:22]=[CH:23][CH:24]=[CH:25][CH:26]=1

Participants

5

Reactant 3

HCID 8028TetrahydrofuranHCID 10246109rac-2-chloro-3,4-dihydro-2,5,7,8-tetramethyl-6-(phenylmethoxy)-2H-1-benzopyranHCID 178418473HCID 178418473, compound

Product 1

HCID 14210609rac-3,4-dihydro-2,5,7,8-tetramethyl-2-(2-propenyl)-6-(phenylmethoxy)-2H-1-benzopyranYield 57.2%

Reagents, catalysts & solvents 1

HCID 3283Diethyl EtherSolvent

Procedure

To 12 mL (24 mmol) of 2M allylmagnesium chloride in tetrahydrofuran, cooled in an ice bath, was added, with stirring, a solution of 4.95 g (14.98 mmol) of rac-2-chloro-3,4-dihydro-2,5,7,8-tetramethyl-6-(phenylmethoxy)-2H-1-benzopyran in 60 mL of anhydrous ether. The reaction mixture was stirred at 0° C. for 6 hr then worked up by being poured into cold, saturated NH4Cl solution and ether extraction. The product (5.4 g of a pale-yellow oil) was dissolved in 40 mL of methanol and 10 mL of ether containing 10 mg of p-toluenesulfonic acid monohydrate. The solution was stirred at room temperature for 21 hr then concentrated in vacuo. The residue was chromatographed on 75 g of silica gel. Elution with 40:1 parts by volume hexane-ether gave 2.88 g (57.2% yield) of rac-3,4-dihydro-6-(phenylmethoxy)-2-(2-propenyl)-2,5,7,8-tetramethyl-2H-1-benzopyran as a colorless oil.

Workup

  1. additionwas added
  2. stirringThe reaction mixture was stirred at 0° C. for 6 hr
  3. additionby being poured into cold,
  4. extractionsaturated NH4Cl solution and ether extraction
  5. dissolutionThe product (5.4 g of a pale-yellow oil) was dissolved in 40 mL of methanol
  6. stirringThe solution was stirred at room temperature for 21 hr
  7. concentrationthen concentrated in vacuo
  8. customThe residue was chromatographed on 75 g of silica gel
  9. washElution with 40:1 parts by volume hexane-ether

Sources & evidence

ORD record
ord-9c33e66b64ab43acafbf9d126d31df3e
Source dataset
uspto-grants-1989_04
Patent number
US04824971

Reaction notes

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