Pyridine → 2,6-Di-tert-butyl-4-[(pyrazin-2-yl)imino]cyclohexa-2,5-dien-1-one

HRID 345761Notes

Reaction equation

HRID 345761 reaction equation
[C:1]([C:5]1[C:6](=[O:16])[C:7]([C:12]([CH3:15])([CH3:14])[CH3:13])=[CH:8][C:9](=O)[CH:10]=1)([CH3:4])([CH3:3])[CH3:2].[NH2:17][C:18]1[CH:23]=[N:22][CH:21]=[CH:20][N:19]=1.O1CCCC1.N1C=CC=CC=1>ClC(Cl)C.[Ti](Cl)(Cl)(Cl)Cl>[C:1]([C:5]1[C:6](=[O:16])[C:7]([C:12]([CH3:15])([CH3:14])[CH3:13])=[CH:8][C:9](=[N:17][C:18]2[CH:23]=[N:22][CH:21]=[CH:20][N:19]=2)[CH:10]=1)([CH3:4])([CH3:3])[CH3:2]

Participants

7

Reactant 4

HCID 1049Pyridine3×HCID 8028TetrahydrofuranHCID 128672,6-Di-t-butyl-p-benzoquinoneHCID 78747Aminopyrazine

Product 1

HCID 143736662,6-Di-tert-butyl-4-[(pyrazin-2-yl)imino]cyclohexa-2,5-dien-1-one

Reagents, catalysts & solvents 2

HCID 24193Titanium TetrachlorideCatalyst3×HCID 63651,1-DichloroethaneSolvent3×

Procedure

A 47 g quantity of 2,6-di-tert-butyl-1,4-benzoquinone and 20 g of aminopyrazine were added to 300 ml of tetrahydrofuran and dissolved therein with heating. To the solution was added a yellow suspension (which had been prepared by adding 12 ml of titanium tetrachloride dropwise with ice-cooling and stirring to a solution of 35 ml of pyridine in 200 ml of dichloroethane), and the mixture was refluxed with heating for 1 hour. To the reaction mixture was added a suspension of 70 ml of pyridine, 24 ml of titanium tetrachloride and 200 ml of dichloroethane. The resulting mixture was refluxed with heating for 2 hours. Again a suspension of 17 ml of pyridine, 6 ml of titanium tetrachloride and 100 ml of dichloroethane was added thereto and the resulting mixture was refluxed with heating for 30 minutes. Then, the reaction mixture was cooled to room temperature and filtered through a Celite pad and the insoluble materials were washed there with ethyl acetate. The filtrate was concentrated and the resulting crude product was purified by silica gel column chromatography (eluent: diethyl ether-hexane=1:10→1:1), and washed with cold hexane, thereby giving 58 g of 2,6-di-tert-butyl-4-pyrazinylimino-2,5-cyclohexadien-1-one (Compound 1a) as a yellow solid.

Workup

  1. dissolutiondissolved
  2. temperaturewith heating
  3. additionTo the solution was added a yellow suspension (which
  4. customhad been prepared
  5. temperaturecooling
  6. temperaturewas refluxed
  7. temperaturewith heating for 1 hour
  8. additionTo the reaction mixture was added
  9. temperatureThe resulting mixture was refluxed
  10. temperaturewith heating for 2 hours
  11. additionwas added
  12. temperaturethe resulting mixture was refluxed
  13. temperaturewith heating for 30 minutes
  14. filtrationfiltered through a Celite pad
  15. washthe insoluble materials were washed there with ethyl acetate
  16. concentrationThe filtrate was concentrated
  17. customthe resulting crude product was purified by silica gel column chromatography (eluent: diethyl ether-hexane=1:10→1:1)
  18. washwashed with cold hexane

Sources & evidence

ORD record
ord-ff513febc140488ca6b349f4fa1a083f
Source dataset
uspto-grants-1991_10
Patent number
US05059598

Reaction notes

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