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

HRID 1579439Notes

Reaction equation

HRID 1579439 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, and the reaction mixture is allowed to stand overnight. The isopropyl alcohol is distilled off under reduced pressure, an aqueous carbonate solution is added to the residue, and then the mixture is extracted with chloroform. The chloroform layer is dried, and the chloroform is distilled off. The residue is recrystallized from isopropyl alcohol 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. distillationThe isopropyl alcohol is distilled off under reduced pressure
  3. additionan aqueous 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 alcohol

Sources & evidence

ORD record
ord-2823570bf21c4277a291a19a85220975
Source dataset
uspto-grants-1976_01
Patent number
US03931205

Reaction notes

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