Phenol → 10H-[1]Benzopyrano[3,2-b]pyridin-10-one

HRID 1731739Notes

Reaction equation

HRID 1731739 reaction equation
Cl[C:2]1[N:10]=[CH:9][CH:8]=[CH:7][C:3]=1C(O)=O.[O-:11][C:12]1[CH:17]=[CH:16][CH:15]=[CH:14][CH:13]=1.[C:18]1([OH:24])C=CC=CC=1>O>[N:10]1[C:2]2[C:18](=[O:24])[C:17]3[C:12](=[CH:13][CH:14]=[CH:15][CH:16]=3)[O:11][C:3]=2[CH:7]=[CH:8][CH:9]=1

Participants

5

Reactant 3

HCID 996PhenolHCID 762582-Chloronicotinic acidHCID 119047Phenolate

Product 1

HCID 756683710H-[1]Benzopyrano[3,2-b]pyridin-10-oneYield 50%

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Procedure

According to the invention, 2-chloronicotinic acid in alkaline metal salt form is reacted with alkaline metal phenoxide without an excess of phenol at 160°-200° C. The molten mass is partly cooled, water is added until complete solubilization, the aqueous solution is acidified and the solid obtained is dried. In the cyclization step the thus obtained 2-phenoxynicotinic acid is added portionwise to 5-10 times its weight of polyphosphoric acid which has been previously heated, the temperature is raised to 160°-200° C., the reaction mixture is cooled and diluted with water. Concentrated aqueous alkali hydroxide is added to adjust the pH to 2-3, the solid is filtered, washed, dried and recrystallized, obtaining very pure 1-azaxanthone in an overall yield of 50-70%.

Workup

  1. temperatureThe molten mass is partly cooled
  2. customthe solid obtained
  3. customis dried
  4. additionIn the cyclization step the thus obtained 2-phenoxynicotinic acid is added portionwise to 5-10 times its weight of polyphosphoric acid which
  5. temperaturehas been previously heated
  6. temperaturethe temperature is raised to 160°-200° C.
  7. temperaturethe reaction mixture is cooled
  8. additiondiluted with water
  9. additionConcentrated aqueous alkali hydroxide is added
  10. filtrationthe solid is filtered
  11. washwashed
  12. customdried
  13. customrecrystallized

Sources & evidence

ORD record
ord-94804006eab741d6a84c502aeb2ae0fd
Source dataset
uspto-grants-1986_11
Patent number
US04623648

Reaction notes

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