Ethyl 4,5-dihydro-4-oxo-5-phenylpyrano[3,2-b]indole-2-carboxylate → 4,5-Dihydro-4-oxo-5-phenylpyrano[3,2-b]indole-2-carboxylic acid

HRID 26160Notes

Reaction equation

HRID 26160 reaction equation
[O:1]=[C:2]1[C:7]2[N:8]([C:15]3[CH:20]=[CH:19][CH:18]=[CH:17][CH:16]=3)[C:9]3[CH:10]=[CH:11][CH:12]=[CH:13][C:14]=3[C:6]=2[O:5][C:4]([C:21]([O:23]CC)=[O:22])=[CH:3]1>C(O)(=O)C.Cl>[O:1]=[C:2]1[C:7]2[N:8]([C:15]3[CH:16]=[CH:17][CH:18]=[CH:19][CH:20]=3)[C:9]3[CH:10]=[CH:11][CH:12]=[CH:13][C:14]=3[C:6]=2[O:5][C:4]([C:21]([OH:23])=[O:22])=[CH:3]1

Participants

4

Reactant 1

HCID 12628412Ethyl 4,5-dihydro-4-oxo-5-phenylpyrano[3,2-b]indole-2-carboxylate

Product 1

HCID 126284294,5-Dihydro-4-oxo-5-phenylpyrano[3,2-b]indole-2-carboxylic acid

Reagents, catalysts & solvents 2

HCID 176Acetic AcidSolventHCID 313Hydrochloric AcidSolvent

Procedure

A mixture of 1.0 g (0.0033 mole) of ethyl 4,5-dihydro-4-oxo-5-phenylpyrano [3,2-b]indole-2-carboxylate in 10 ml glacial acetic acid and 2.0 ml conc. hydrochloric acid was stirred at reflux for 41/2 hr, then cooled and added to 75 g ice - H2O. The solid was filtered, washed with cold water, then added to a mixture of 35 ml 5% aqueous sodium carbonate and 250 ml water. After filtering by gravity, tha aqueous solution was washed three times with 75 ml chloroform, cooled in ice, and acidified with 4.0 N hydrochloric acid. The orange precipitate was filtered, digested 15 min on the steam bath with 25 ml water and re-filtered warm. Recrystallization from DMF-water yielded an off-white solid of mpt.>290°.

Workup

  1. temperatureat reflux for 41/2 hr
  2. temperaturecooled
  3. filtrationThe solid was filtered
  4. washwashed with cold water
  5. additionadded to a mixture of 35 ml 5% aqueous sodium carbonate and 250 ml water
  6. filtrationAfter filtering by gravity
  7. washtha aqueous solution was washed three times with 75 ml chloroform
  8. temperaturecooled in ice
  9. filtrationThe orange precipitate was filtered
  10. filtrationre-filtered
  11. temperaturewarm
  12. customRecrystallization from DMF-water
  13. customyielded an off-white solid of mpt
  14. custom>290°

Sources & evidence

ORD record
ord-0a202b9cede1473991f009021cb0bc23
Source dataset
uspto-grants-1979_04
Patent number
US04148806

Reaction notes

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