Toluene → Benzopyran

HRID 904070Notes

Reaction equation

HRID 904070 reaction equation
[PH4+].[O:2]1[CH2:6][CH2:5][CH:4]=P1.[C:7]1(C)[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1>>[O:2]1[C:12]2[C:7](=[CH:8][CH:9]=[CH:10][CH:11]=2)[CH:4]=[CH:5][CH2:6]1

Participants

4

Reactant 3

HCID 1140TolueneHCID 5460504PhosphoniumHCID 85815858HCID 85815858, compound

Product 1

HCID 9211Benzopyran

Procedure

The cyclisation is effected by dropwise addition of a solution of sodium t-amylate in toluene to the aforementioned phosphonium salt in suspension in the same solvent heated under reflux. After each addition, the yellow colouring of the phosphorane appears and then disappears almost immediately. After filtration of the sodium bromide, the toluene is evaporated and the 3-methyl chrom-3-ene is separated from the triphenyl phosphine oxide by a treatment with pentane.

Workup

  1. temperatureheated
  2. temperatureunder reflux
  3. additionAfter each addition
  4. filtrationAfter filtration of the sodium bromide
  5. customthe toluene is evaporated
  6. customthe 3-methyl chrom-3-ene is separated from the triphenyl phosphine oxide by a treatment with pentane

Sources & evidence

ORD record
ord-26aaabed10b44233a33ef03ed4751934
Source dataset
uspto-grants-1980_10
Patent number
US04230624

Reaction notes

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