4-Chlorophenylboronic acid → 2-Chloro-3-(4-chlorophenyl)pyrazine

HRID 220422Notes

Reaction equation

HRID 220422 reaction equation
Cl[C:2]1[C:7]([Cl:8])=[N:6][CH:5]=[CH:4][N:3]=1.[Cl:9][C:10]1[CH:15]=[CH:14][C:13](B(O)O)=[CH:12][CH:11]=1.[F-].[K+]>C1(C)C=CC=CC=1.O.C1C=CC([P]([Pd]([P](C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)([P](C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)[P](C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1>[Cl:8][C:7]1[C:2]([C:13]2[CH:14]=[CH:15][C:10]([Cl:9])=[CH:11][CH:12]=2)=[N:3][CH:4]=[CH:5][N:6]=1

Participants

7

Reactant 3

HCID 742994-Chlorophenylboronic acidHCID 785752,3-DichloropyrazineHCID 522689Potassium Fluoride

Product 1

HCID 131998892-Chloro-3-(4-chlorophenyl)pyrazineYield 44%

Reagents, catalysts & solvents 3

HCID 178418397HCID 178418397, compoundCatalystHCID 962WaterSolventHCID 1140TolueneSolvent

Procedure

Couple 2,3-dichloropyrazine (0.302 g, 2.03 mmol) and 4-chlorophenylboronic acid (0.320 g, 2.05 mmol), using tetrakis(triphenylphosphine)palladium(0) (0.124 g, 0.107 mmol), and potassium fluoride (0.355 g, 6.11 mmol) in toluene (19 mL) and water (5 mL), at 100° C. for 17.5 hr. Cool the reaction, partition the layers and extract the aqueous layer with ethyl acetate. Wash the combined organic layers with saturated aqueous sodium chloride, dry (magnesium sulfate), concentrate and purify (silica gel chromatography, eluting with 0:100 to 35:65 ethyl acetate:hexanes), to give 2-chloro-3-(4-chlorophenyl)-pyrazine (0.199 g, 44%).

Workup

  1. temperatureCool
  2. customthe reaction
  3. custompartition the layers
  4. extractionextract the aqueous layer with ethyl acetate
  5. washWash the combined organic layers with saturated aqueous sodium chloride
  6. dry with materialdry (magnesium sulfate)
  7. concentrationconcentrate
  8. custompurify
  9. wash(silica gel chromatography, eluting with 0:100 to 35:65 ethyl acetate:hexanes)

Sources & evidence

ORD record
ord-cc47dafb70e745de988046168d5d84ac
Source dataset
uspto-grants-2012_06
Patent number
US08202873B2

Reaction notes

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