Hydrochloric Acid → 5H-[1]benzopyrano[2,3-b]pyridine

HRID 1579377Notes

Reaction equation

HRID 1579377 reaction equation
O[CH:2]1[C:11]2[C:6](=[N:7][CH:8]=[CH:9][CH:10]=2)[O:5][C:4]2[CH:12]=[CH:13][CH:14]=[CH:15][C:3]1=2.Cl>C(O)(C)C>[N:7]1[CH:8]=[CH:9][CH:10]=[C:11]2[CH2:2][C:3]3[CH:15]=[CH:14][CH:13]=[CH:12][C:4]=3[O:5][C:6]=12

Participants

4

Reactant 2

HCID 313Hydrochloric AcidHCID 1928305H-[1]Benzopyrano[2,3-b]pyridin-5-ol

Product 1

HCID 122742075H-[1]benzopyrano[2,3-b]pyridineYield 81.5%

Reagents, catalysts & solvents 1

HCID 3776IsopropanolSolvent2×

Procedure

A mixture of 10 g of 5-hydroxy-5H-[1]benzopyrano[2,3-b]pyridine, 100 ml of isopropyl alcohol and 10 ml of 20% hydrochloric acid in isopropyl alcohol is refluxed for 3 hours. The reaction mixture is allowed to stand overnight, and then the isopropyl alcohol is removed by distillation under reduced pressure. An aqueous potassium carbonate solution is added to the residue, and the mixture is extracted with chloroform. The chloroform layer is dried, and the chloroform is distilled off. The residue is recrystallized from isopropyl ether or carbon tetrachloride to give 7.5 g of 5H-[1]benzopyrano[2,3-b]pyridine as white crystals melting at 87°-88°C.

Workup

  1. temperatureis refluxed for 3 hours
  2. customthe isopropyl alcohol is removed by distillation under reduced pressure
  3. additionAn aqueous potassium carbonate solution is added to the residue
  4. extractionthe mixture is extracted with chloroform
  5. dry with materialThe chloroform layer is dried
  6. distillationthe chloroform is distilled off
  7. customThe residue is recrystallized from isopropyl ether or carbon tetrachloride

Sources & evidence

ORD record
ord-1d14fcb41b91454bad1208009fdfb212
Source dataset
uspto-grants-1976_01
Patent number
US03931199

Reaction notes

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