2,6-Dichloroisonicotinic acid → tert-Butyl 2,6-dichloropyridine-4-carboxylate

HRID 1395540Notes

Reaction equation

HRID 1395540 reaction equation
[Cl:1][C:2]1[CH:3]=[C:4]([CH:8]=[C:9]([Cl:11])[N:10]=1)[C:5]([OH:7])=[O:6]>S(Cl)(Cl)=O.C1CCCCC1.CN(C)C=O>[Cl:1][C:2]1[CH:3]=[C:4]([CH:8]=[C:9]([Cl:11])[N:10]=1)[C:5]([O:7][C:4]([CH3:8])([CH3:5])[CH3:3])=[O:6]

Participants

5

Reactant 1

HCID 948302,6-Dichloroisonicotinic acid

Product 1

HCID 22594123tert-Butyl 2,6-dichloropyridine-4-carboxylate

Reagents, catalysts & solvents 3

HCID 6228DimethylformamideCatalystHCID 8078CyclohexaneSolventHCID 24386Thionyl ChlorideSolvent

Procedure

A solution of 2,6-dichloroisonicotinic acid (38.4 g, 0.20 mole) in thionyl chloride (60 ml.) and cyclohexane (100 ml) containing a few drops of dimethylformamide is heated at 80° for three hours. The solution is cooled and excess thionyl chloride and cyclohexane are removed in vacuo. The residue is dissolved in chloroform (40 ml.) and added dropwise to a solution of t-butanol (50 ml.) and N,N-dimethylaniline (40 ml.). The solution is heated at reflux for six hours, cooled, diluted with diethyl ether and washed successively with water, water containing 4 ml. of concentrated sulfuric acid, water, dilute sodium carbonate solution and dried over anhydrous sodium sulfate. The solvent is removed under vacuum and the residue is crystallized from a minimum amount of methanol to give 24 g. of product, m.p. 79°-81°.

Workup

  1. temperatureis heated at 80° for three hours
  2. temperatureThe solution is cooled
  3. customexcess thionyl chloride and cyclohexane are removed in vacuo
  4. dissolutionThe residue is dissolved in chloroform (40 ml.)
  5. additionadded dropwise to a solution of t-butanol (50 ml.) and N,N-dimethylaniline (40 ml.)
  6. temperatureThe solution is heated
  7. temperatureat reflux for six hours
  8. temperaturecooled
  9. additiondiluted with diethyl ether
  10. washwashed successively with water, water containing 4 ml
  11. dry with materialof concentrated sulfuric acid, water, dilute sodium carbonate solution and dried over anhydrous sodium sulfate
  12. customThe solvent is removed under vacuum
  13. customthe residue is crystallized from a minimum amount of methanol
  14. customto give 24 g

Sources & evidence

ORD record
ord-3ecd46b7ef704e499fe42404cd0cd67f
Source dataset
uspto-grants-1980_05
Patent number
US04203988

Reaction notes

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