Hydrochloric Acid → 5H-[1]benzopyrano[2,3-b]pyridine-7-carboxylic acid

HRID 1579398Notes

Reaction equation

HRID 1579398 reaction equation
[N:1]1[CH:6]=[CH:5][CH:4]=[C:3]2[CH2:7][C:8]3[CH:14]=[C:13]([C:15]([O:17]C(C)C)=[O:16])[CH:12]=[CH:11][C:9]=3[O:10][C:2]=12.Cl>C(O)(=O)C>[N:1]1[CH:6]=[CH:5][CH:4]=[C:3]2[CH2:7][C:8]3[CH:14]=[C:13]([C:15]([OH:17])=[O:16])[CH:12]=[CH:11][C:9]=3[O:10][C:2]=12

Participants

4

Reactant 2

HCID 313Hydrochloric AcidHCID 21568408isopropyl 5H-[1]benzopyrano[2,3-b]pyridine-7-carboxylate

Product 1

HCID 127901195H-[1]benzopyrano[2,3-b]pyridine-7-carboxylic acidYield 87.1%

Reagents, catalysts & solvents 1

HCID 176Acetic AcidSolvent

Procedure

A mixture of 3.4 g of isopropyl 5H-[1]benzopyrano[ 2,3-b]pyridine-7-carboxylate, 7 ml of concentrated hydrochloric acid and 17 ml of acetic acid is heated under reflux on an oil bath for 3 hours. The reaction mixture is concentrated, and a small amount of water is added to the residue. The mixture is adjusted to pH 2-3 by addition of 10% sodium hydroxide. The crystalline precipitate is filtered off and recrystallized from acetic acid to give 2.5 g of 5H-[1]benzopyrano[2,3-b]pyridine-7-carboxylic acid melting at 285°-286°C.

Workup

  1. temperatureis heated
  2. temperatureunder reflux on an oil bath for 3 hours
  3. concentrationThe reaction mixture is concentrated
  4. additiona small amount of water is added to the residue
  5. additionThe mixture is adjusted to pH 2-3 by addition of 10% sodium hydroxide
  6. filtrationThe crystalline precipitate is filtered off
  7. customrecrystallized from acetic acid

Sources & evidence

ORD record
ord-e13382bac6284bba9472f7610d1dfb33
Source dataset
uspto-grants-1976_01
Patent number
US03931199

Reaction notes

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