2H-chromen-6-ol → 3,4-Dihydro-2H-1-benzopyran-6-ol

HRID 1788999Notes

Reaction equation

HRID 1788999 reaction equation
[OH:1][C:2]1[CH:3]=[CH:4][C:5]2[O:10][CH2:9][CH:8]=[CH:7][C:6]=2[CH:11]=1>C1C=CC=CC=1.C1C=CC(P(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1.C1C=CC(P(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1.C1C=CC(P(C2C=CC=CC=2)C2C=CC=CC=2)=CC=1.[Cl-].[Rh]>[OH:1][C:2]1[CH:3]=[CH:4][C:5]2[O:10][CH2:9][CH2:8][CH2:7][C:6]=2[CH:11]=1

Participants

4

Reactant 1

HCID 134376782H-chromen-6-ol

Product 1

HCID 151223383,4-Dihydro-2H-1-benzopyran-6-olYield 93%

Reagents, catalysts & solvents 2

HCID 84599Chlorotris(triphenylphosphine)rhodium(I)CatalystHCID 241BenzeneSolvent

Procedure

The 6-hydroxybenzopyran (1.5 g; 10 mM) was dissolved in 100 ml of anhydrous benzene along with Wilkinson's catalyst (280 mgs; 0.30 mM). This hydrogenation bottle containing this reaction mixture was first flushed with nitrogen and then with hydrogen. The bottle was pressurized to 40 psi in a Paar shaker and agitated for 40 minutes at which time the pressure in the bottle (400 ml dead volume) had dropeed to 30 psi and was dropping no further. The bottle was then flushed with nitrogen and the solvent was removed in vacuo. The residue was taken up in ether and filtered through a pad of celite. The solvent was removed and the oil was purified by flash chromatography on a 30 mm×6" column of silica gel eluted with 600 ml of 20% ethyl acetate in hexane. This purification produced 1.40 g (93%) of 2,3-dihydro-6-hydroxybenzopyran as a white crystalline solid.

Workup

  1. additionThis hydrogenation bottle containing this reaction mixture
  2. customwas first flushed with nitrogen
  3. customThe bottle was then flushed with nitrogen
  4. customthe solvent was removed in vacuo
  5. filtrationfiltered through a pad of celite
  6. customThe solvent was removed
  7. customthe oil was purified by flash chromatography on a 30 mm×6" column of silica gel
  8. washeluted with 600 ml of 20% ethyl acetate in hexane
  9. customThis purification

Sources & evidence

ORD record
ord-df11ba087625413d92e76cfa78b4056e
Source dataset
uspto-grants-1987_08
Patent number
US04686235

Reaction notes

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