Carbon tetrabromide → HCID 18449299, compound

HRID 1270208Notes

Reaction equation

HRID 1270208 reaction equation
[C:1]1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.C(Br)(Br)(Br)Br.[CH3:25][O:26][C:27]1[CH:34]=[C:33]([O:35][CH3:36])[C:32]([C:37]2[S:38][CH:39]=[CH:40][CH:41]=2)=[CH:31][C:28]=1[CH:29]=O>ClCCl>[C:29]([C:28]1[C:27]([O:26][CH3:25])=[CH:34][C:33]([O:35][CH3:36])=[C:32]([C:37]2[S:38][CH:39]=[CH:40][CH:41]=2)[CH:31]=1)#[CH:1]

Participants

5

Reactant 3

HCID 11205Carbon tetrabromideHCID 11776TriphenylphosphineHCID 161161832,4-Dimethoxy-5-thien-2-ylbenzaldehyde

Product 1

HCID 18449299HCID 18449299, compoundYield 67.1%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent

Conditions

Temperature
-78 °C

Procedure

Ex-1B: A solution of triphenylphosphine (8.64 g, 32.9 mmol) and CBr4 (5.4 g, 16.3 mmol) in 140 mL of dichloromethane was stirred at room temperature for 15 min. Then 2,4-dimethoxy-5-thiophen-2-yl-benzaldehyde (3.1 g, 12.5 mmol) from Ex-1A was added, and the mixture was stirred overnight. The solvent was reduced to 30 mL and then filtered through silica gel with hexanes as eluent. After evaporation of the solvents, the crude 2-[5-(2,2-dibromo-vinyl)-2,4-dimethoxy-phenyl]-thiophene was dissolved in THF (40 mL) and cooled to −78° C. Then n-butyllithium (25.6 mmol, 16 mL of a 1.6 M solution in hexanes) was added dropwise while maintaining an internal temperature below −70° C. After stirring the reaction mixture for 1 h at −78° C., the reaction was quenched with a saturated NH4Cl solution. This solution was extracted with ethyl acetate, and the organic layer was dried over anhydrous magnesium sulfate. The solvent was removed under reduced pressure, and the residue was chromatographed on silica gel (hexane/ethyl acetate, 1:1) to give 2.05 g (67%) of 2-(5-ethynyl-2,4-dimethoxy-phenyl)-thiophene as a yellow solid, m.p. 141–142° C. 1H-NMR (300 MHz, CDCl3) δ 7.73 (s, 1H), 7.38 (dd, 1H, J=3.7 and 1.3 Hz), 7.28 (dd, 1H, J=5.2 and 1.3 Hz), 7.06 (dd, 1H, J=5.2 and 3.7 Hz), 6.51 (s, 1H), 3.96 (s, 6H), 3.27 (s, 1H).

Workup

  1. filtrationfiltered through silica gel with hexanes as eluent
  2. customAfter evaporation of the solvents
  3. dissolutionthe crude 2-[5-(2,2-dibromo-vinyl)-2,4-dimethoxy-phenyl]-thiophene was dissolved in THF (40 mL)
  4. additionThen n-butyllithium (25.6 mmol, 16 mL of a 1.6 M solution in hexanes) was added dropwise
  5. temperaturewhile maintaining an internal temperature below −70° C
  6. stirringAfter stirring the reaction mixture for 1 h at −78° C.
  7. customthe reaction was quenched with a saturated NH4Cl solution
  8. extractionThis solution was extracted with ethyl acetate
  9. dry with materialthe organic layer was dried over anhydrous magnesium sulfate
  10. customThe solvent was removed under reduced pressure
  11. customthe residue was chromatographed on silica gel (hexane/ethyl acetate, 1:1)

Sources & evidence

ORD record
ord-72195d84aab147ac91e337ad30beb69d
Source dataset
uspto-grants-2007_04
Patent number
US07202247B2

Reaction notes

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