5,6-Dichloropyridine-3-carbaldehyde → 2,3-Dichloro-5-ethenylpyridine

HRID 1942261Notes

Reaction equation

HRID 1942261 reaction equation
[CH3:1]C(C)([O-])C.[K+].[Cl:7][C:8]1[C:13]([Cl:14])=[CH:12][C:11]([CH:15]=O)=[CH:10][N:9]=1>[Br-].C[P+](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1.C1(C)C=CC=CC=1.O1CCCC1.[Cl-].[Na+].O.C(OCC)(=O)C>[Cl:7][C:8]1[C:13]([Cl:14])=[CH:12][C:11]([CH:15]=[CH2:1])=[CH:10][N:9]=1

Participants

8

Reactant 2

HCID 115356545,6-Dichloropyridine-3-carbaldehydeHCID 23665647Potassium tert-butoxide

Product 1

HCID 574168492,3-Dichloro-5-ethenylpyridineYield 70.1%

Reagents, catalysts & solvents 5

HCID 74505Methyltriphenyliphosphonium bromideCatalystHCID 1140TolueneSolventHCID 8028TetrahydrofuranSolventHCID 8857Ethyl AcetateSolventHCID 57417360Sodium chloride; waterSolvent

Conditions

Temperature
-20 °C

Procedure

To a cooled 0° C., stirred slurry of methyltriphenylphosphonium bromide (10.0 g) in toluene (200 mL) was added potassium t-butoxide (3.07 g) portionwise to produce a yellow slurry. After 1 hr, the reaction mixture was cooled to −20° C. and 2,3-dichloro-5-formylpyridine (2, 4.0 grams, 22.72 mMol) which dissolved in tetrahydrofuran (6 mL) was added dropwise to produce a purple colored slurry. The reaction mixture was warmed to 0° C. and stirred for additional 1 hr. Then the reaction mixture was treated with saturated aqueous brine (150 mL) and diluted with ethyl acetate (200 mL). The resulting organic layer was washed with brine, dried over anhydrous sodium sulfate and concentrated in vacuo. The crude product was purified by silica gel chromatography column eluting with a gradient of ethyl acetate (0-10%)/hexanes to afford 2.77 g of the desired product 3 (70%). 1H NMR (400 MHz, CDCl3) δ 8.30 (1H, d, J=2.19 Hz), 7.80 (1H, d, J=2.19 Hz), 6.63 (1H, dd, J=10.96, 17.80 Hz), 5.86 (1H, d, J=17.80 Hz), 5.45 (1H, d, J=10.96 Hz). LC/MS (M+1): 174.

Workup

  1. customto produce a yellow slurry
  2. additionwas added dropwise
  3. customto produce a purple colored slurry
  4. temperatureThe reaction mixture was warmed to 0° C.
  5. washThe resulting organic layer was washed with brine
  6. dry with materialdried over anhydrous sodium sulfate
  7. concentrationconcentrated in vacuo
  8. customThe crude product was purified by silica gel chromatography column
  9. washeluting with a gradient of ethyl acetate (0-10%)/hexanes

Sources & evidence

ORD record
ord-2609db9582a348abb7eeb9760530522e
Source dataset
uspto-grants-2013_03
Patent number
US08389549B2

Reaction notes

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