Triethylamine → rac-3,4-dihydro-2,5,7,8-tetramethyl-2-[(2-thienyl) ethynyl]-2H-1-benzopyran-6ol

HRID 2050955Notes

Reaction equation

HRID 2050955 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[S:20][CH:21]=[CH:22][CH:23]=1.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C(N(CC)CC)C>C(#N)C>[CH3:17][C:3]1([C:1]#[C:2][C:19]2[S:20][CH:21]=[CH:22][CH:23]=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

6

Reactant 4

HCID 8471TriethylamineHCID 11776TriphenylphosphineHCID 189212-IodothiopheneHCID 14478563rac-3,4-dihydro-2-ethynyl-2,5,7,8-tetramethyl-2H-1-benzopyran-6ol

Product 1

HCID 9904883rac-3,4-dihydro-2,5,7,8-tetramethyl-2-[(2-thienyl) ethynyl]-2H-1-benzopyran-6olYield 56%

Reagents, catalysts & solvents 1

HCID 6342AcetonitrileSolvent

Procedure

A mixture of 4.6 g (20 mmol) of rac-3,4-dihydro-2-ethynyl-2,5,7,8-tetramethyl-2H-1-benzopyran -6ol, 6.3 g (30 mmol) of 2-iodothiophene, 0.8 g of triphenylphosphine, 0.19 g of cuprous iodide, 6 ml of triethylamine and 200 ml of acetonitrile was stirred and degassed with argon for 15 minutes. Palladium acetate, 220 mg, was then added and stirring under argon was continued for 4 hours. The solvent was removed under reduced pressure and the residue was partitioned between methylene chloride and saturated aqueous sodium bicarbonate solution. The organic phase was separated, dried and evaporated. The residue was chromato graphed over 200 g of silica gel (Merck 70-230 mesh) using methylene chloride. Crystallization of the combined clean fractions from ether/hexane yielded 3.5 g (56 %) of rac-3,4-dihydro-2,5,7,8-tetramethyl-2-[(2-thienyl) ethynyl]-2H-1-benzopyran-6ol with m.p. 112-114° C.

Workup

  1. customdegassed with argon for 15 minutes
  2. additionPalladium acetate, 220 mg, was then added
  3. stirringstirring under argon
  4. customThe solvent was removed under reduced pressure
  5. customthe residue was partitioned between methylene chloride and saturated aqueous sodium bicarbonate solution
  6. customThe organic phase was separated
  7. customdried
  8. customevaporated
  9. customCrystallization of the combined clean fractions from ether/hexane

Sources & evidence

ORD record
ord-e6d5e2e39bda4f06b821fc5f0ec09582
Source dataset
uspto-grants-1991_05
Patent number
US05015661

Reaction notes

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