Hydrochloric Acid → Pyrazine, 2-phenyl-

HRID 1602130Notes

Reaction equation

HRID 1602130 reaction equation
Cl[C:2]1[CH:7]=[N:6][CH:5]=[CH:4][N:3]=1.[C:8]1([Mg]Br)[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1.Cl>C1COCC1.C1C=CC(P(C2C=CC=CC=2)CCP(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1.Cl[Ni]Cl>[C:8]1([C:2]2[CH:7]=[N:6][CH:5]=[CH:4][N:3]=2)[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=1

Participants

6

Reactant 3

HCID 313Hydrochloric AcidHCID 73277ChloropyrazineHCID 178418255HCID 178418255, compound

Product 1

HCID 642870Pyrazine, 2-phenyl-Yield 39%

Reagents, catalysts & solvents 2

HCID 2734542[1,2-Bis(diphenylphosphino)ethane]dichloronickel(II)CatalystHCID 8028TetrahydrofuranSolvent

Procedure

Chloropyrazine (20.68 gram, 177 mmol) and [1,2-bis(diphenylphosphino)ethane]nickel(II) chloride (41.08 gram, 77.8 mmol) in dry THF (1.5 liter) were mixed and stirred for 80 minutes in a flask (cooled with a water bath) under nitrogen. A solution of phenylmagnesium bromide (3M in Et2O) (103 ml, 309 mmol) was added slowly through a dropping funnel into the cooled brick-red slurry at room temperature under nitrogen over 3.5 hours. After stirring at room temperature overnight, TLC showed that the reaction was complete. 3 N HCl (100 ml) was added slowly through a dropping funnel under nitrogen and the mixture was stirred for one hour. The THF layer was separated from the aqueous layer. The aqueous layer was adjusted to pH 12 with 6 N NaOH and extracted with EtOAc (100 ml, 3×). The organic fractions (THF and EtOAc) were combined and dried over MgSO4, filtered and concentrated to give a solid. The product was purified by flash chromatography on 300 g of flash grade silica gel in 2.5% EtOAc/CH2Cl2 to give 10.79 gram (69 mmol, 39%) of 2-phenylpyrazine, m.p. 69-70° C.; FAB mass [M+1]+ 157;

Workup

  1. temperature(cooled with a water bath) under nitrogen
  2. stirringAfter stirring at room temperature overnight
  3. stirringthe mixture was stirred for one hour
  4. customThe THF layer was separated from the aqueous layer
  5. extractionextracted with EtOAc (100 ml, 3×)
  6. dry with materialdried over MgSO4
  7. filtrationfiltered
  8. concentrationconcentrated
  9. customto give a solid
  10. customThe product was purified by flash chromatography on 300 g of flash grade silica gel in 2.5% EtOAc/CH2Cl2

Sources & evidence

ORD record
ord-481e5ba87fef4717a1adc90fbf3d9afc
Source dataset
uspto-grants-1999_11
Patent number
US05981520

Reaction notes

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