Water → 3-(4-Fluorophenyl)-5,7-dihydroxy-2-methyl-4H-1-benzopyran-4-one

HRID 1764737Notes

Reaction equation

HRID 1764737 reaction equation
O[C:2]1C=C(O)C=C(O)[C:3]=1[CH:10]([C:18](C(C1C(O)=CC(O)=CC=1O)C1C=CC(F)=CC=1)=[O:19])[C:11]1[CH:16]=[CH:15][C:14]([F:17])=[CH:13][CH:12]=1.B(F)(F)F.CC[O:43][CH2:44][CH3:45].CS(Cl)(=O)=O.[OH2:51]>CC(N(C)C)=O>[OH:51][C:3]1[C:10]2[C:18](=[O:19])[C:10]([C:11]3[CH:16]=[CH:15][C:14]([F:17])=[CH:13][CH:12]=3)=[C:3]([CH3:2])[O:19][C:18]=2[CH:45]=[C:44]([OH:43])[CH:2]=1

Participants

6

Reactant 4

HCID 962WaterHCID 8000Boron trifluoride etherateHCID 31297Methanesulfonyl chlorideHCID 86736045HCID 86736045, compound

Product 1

HCID 227693163-(4-Fluorophenyl)-5,7-dihydroxy-2-methyl-4H-1-benzopyran-4-one

Reagents, catalysts & solvents 1

HCID 31374DimethylacetamideSolvent2×

Procedure

2,4,6-Trihydroxy-phenyl 4-fluoro-benzyl-ketone (1.31 g, 5 mmole) was dissolved in dimethylacetamide (5.0 ml) and borontrifluoride etherate (2.1 g, 15 mmole) was added cautiously. This solution was then added to a solution of methane-sulphonyl chloride (1.71 g, 15 mmole) in dimethylacetamide (5 ml) and the resulting mixture was heated on the steam batch for 75 minutes. The reaction mixture was poured into cold water (75 ml) and the crystalline diacetate was collected by filtration. The product was hydrolysed by heating in 50% methanolic hydrochloric acid (20 ml, 5N) at reflux for 1 hour, the solution was poured into excess cold water and the crystalline precipitate was collected and dried to give 5,7-dihydroxy-3-p-fluoro-phenyl-2-methyl-4-oxo-4H-benzopyran, m.p. 222°-223°. NMR of the diacetate confirmed that cyclisation had taken place. The product was identical on T.L.C. with a sample prepared via the standard Allen-Robinson synthesis.

Workup

  1. temperaturethe resulting mixture was heated on the steam batch for 75 minutes
  2. filtrationthe crystalline diacetate was collected by filtration
  3. temperatureby heating in 50% methanolic hydrochloric acid (20 ml, 5N)
  4. temperatureat reflux for 1 hour
  5. additionthe solution was poured into excess cold water
  6. customthe crystalline precipitate was collected
  7. customdried

Sources & evidence

ORD record
ord-a41e4abdda4a49a3942f474ee3301aa4
Source dataset
uspto-grants-1978_09
Patent number
US04117149

Reaction notes

Loading…