2-Naphthol → 3H-Naphtho[2,1-b]pyran

HRID 2106628Notes

Reaction equation

HRID 2106628 reaction equation
[CH:1]1[C:10]2[C:5](=[CH:6][CH:7]=[CH:8][CH:9]=2)[CH:4]=[CH:3][C:2]=1[OH:11].[CH:12]1(C(C2CC2)(O)C#C)[CH2:14][CH2:13]1>C1(C)C=CC=CC=1>[CH:13]1[C:1]2[C:10]3[C:5]([CH:4]=[CH:3][C:2]=2[O:11][CH2:14][CH:12]=1)=[CH:6][CH:7]=[CH:8][CH:9]=3

Participants

4

Reactant 2

HCID 86632-NaphtholHCID 5201091,1-dicyclopropylprop-2-yn-1-ol

Product 1

HCID 123289773H-Naphtho[2,1-b]pyran

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent

Procedure

Acidic alumina (20 grams) was added to a solution of 2-naphthol (4.2 grams, 0.03 moles) and 1,1-Dicyclopropylpropyn-1-o1 (3.08 grams, 0.0226 moles) in toluene (30 cc). The mixture was boiled under reflux for three hours and the alumina removed by filtration. The filtrate was washed sequentially with a dilute (10 percent) sodium hydroxide solution and water. The organic layer was extracted with diethyl ether (2×50 cc), dried over anhydrous magnesium sulfate, and filtered. The filtrate was evaporated under reduced pressure leaving a brown oil which was chromatographed on silica gel using petroleum (b.p. 60°-80° C.) as the eluant. The fraction which exhibited a reversible change from colorless to yellow on exposure to the flash from the flash gun of Example 2 was collected. Petroleum solvent was removed under reduced pressure leaving as a colorless oil 0.3 grams of 2,2-Dicyclopropyl- [2-H-2,1b] naphthopyran (i.e., graphic formula III).

Workup

  1. temperatureunder reflux for three hours
  2. customthe alumina removed by filtration
  3. washThe filtrate was washed sequentially with
  4. additiona dilute (10 percent) sodium hydroxide solution and water
  5. extractionThe organic layer was extracted with diethyl ether (2×50 cc)
  6. dry with materialdried over anhydrous magnesium sulfate
  7. filtrationfiltered
  8. customThe filtrate was evaporated under reduced pressure
  9. customleaving a brown oil which
  10. customwas chromatographed on silica gel
  11. customwas collected
  12. customPetroleum solvent was removed under reduced pressure

Sources & evidence

ORD record
ord-f3d62b1b99ff4d869f9f9eee5e9f496c
Source dataset
uspto-grants-1990_06
Patent number
US04931221

Reaction notes

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