Boron Trichloride → 6-Acetyl-2,3,-dihydro-7-hydroxy-4-methyl-4H-1-benzopyran

HRID 236982Notes

Reaction equation

HRID 236982 reaction equation
[C:1]([C:4]1[C:5]([O:15]C)=[CH:6][C:7]2[O:12][CH2:11][CH2:10][CH:9]([CH3:13])[C:8]=2[CH:14]=1)(=[O:3])[CH3:2].B(Cl)(Cl)Cl>C(Cl)Cl>[C:1]([C:4]1[C:5]([OH:15])=[CH:6][C:7]2[O:12][CH2:11][CH2:10][CH:9]([CH3:13])[C:8]=2[CH:14]=1)(=[O:3])[CH3:2]

Participants

4

Reactant 2

HCID 25135Boron TrichlorideHCID 203045486-Acetyl-2,3,-dihydro-7-methoxy-4-methyl-4H-1-benzopyran

Product 1

HCID 203045786-Acetyl-2,3,-dihydro-7-hydroxy-4-methyl-4H-1-benzopyranYield 67.7%

Reagents, catalysts & solvents 1

HCID 6344DichloromethaneSolvent2×

Procedure

The product of step (d) (57.4 g) in dry methylene chloride (500 ml) was treated with boron trichloride (61 g) in dry methylene chloride (150 ml) at -70° C. The cooling bath was removed and the reaction mixture was allowed to warm to room temperature during 1 hour. The reaction mixture was poured into water and the methylene chloride layer was separated, washed with water and dried. Evaporation of the solvent left 55.7 g of crude product; this was dissolved in ether and extracted several times with a sodium hydroxide solution. The basic extracts were acidified and the precipitated product extracted with ether, which was washed with water and dried. Evaporation of the solvent gave 36.4 g of product mp 91°-96°. A recrystallisation from ethanol gave the title compound, mp 104°-105°.

Workup

  1. customThe cooling bath was removed
  2. additionThe reaction mixture was poured into water
  3. customthe methylene chloride layer was separated
  4. washwashed with water
  5. customdried
  6. customEvaporation of the solvent
  7. waitleft 55.7 g of crude product
  8. dissolutionthis was dissolved in ether
  9. extractionextracted several times with a sodium hydroxide solution
  10. extractionthe precipitated product extracted with ether, which
  11. washwas washed with water
  12. customdried
  13. customEvaporation of the solvent

Sources & evidence

ORD record
ord-a623d16e412e4a58948450c6770e7a1e
Source dataset
uspto-grants-1979_06
Patent number
US04159273

Reaction notes

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