Methanesulfonic Acid → 6-Fluoro-2-methyl-4-chromanone

HRID 1722048Notes

Reaction equation

HRID 1722048 reaction equation
[F:1][C:2]1[CH:7]=[CH:6][C:5]([OH:8])=[CH:4][CH:3]=1.[C:9](O)(=[O:13])/[CH:10]=[CH:11]/[CH3:12].CS(O)(=O)=O>O>[F:1][C:2]1[CH:7]=[C:6]2[C:5](=[CH:4][CH:3]=1)[O:8][CH:11]([CH3:12])[CH2:10][C:9]2=[O:13]

Participants

5

Reactant 3

HCID 6395Methanesulfonic AcidHCID 97324-FluorophenolHCID 637090Crotonic Acid

Product 1

HCID 27373906-Fluoro-2-methyl-4-chromanone

Reagents, catalysts & solvents 1

HCID 962WaterSolvent

Conditions

Temperature
92 °C

Procedure

A mixture of 56.1 g (0.5 mol) 4-fluorophenol, 172 g (2 mol) crotonic acid and 1120 ml methane sulfonic acid was heated at 92° C. for 20 hours. The reaction was cooled to 0° C., poured onto 2 liters ice and 2 liters water and extracted with 3×800 ml diethyl ether. The combined organic layers were washed with 3×500 ml water, 4×500 ml 1N sodium hydroxide, 2×500 ml water and 500 ml brine, dried over magnesium sulfate and concentrated in vacuo to give 48.5 g crude solid. The latter was purified by flash chromatography on 1000 cc silica gel using diethyl ether:hexane (1:10) as eluant. The title compound was obtained as a yellow solid, 37 g (41%); m.p. 65°-68° C. The Chemical Abstracts Registry Nos. for this compound are 88754-96-5 and 82320-16-9.

Workup

  1. temperatureThe reaction was cooled to 0° C.
  2. extractionextracted with 3×800 ml diethyl ether
  3. washThe combined organic layers were washed with 3×500 ml water, 4×500 ml 1N sodium hydroxide, 2×500 ml water and 500 ml brine
  4. dry with materialdried over magnesium sulfate
  5. concentrationconcentrated in vacuo
  6. customto give 48.5 g crude solid
  7. customThe latter was purified by flash chromatography on 1000 cc silica gel

Sources & evidence

ORD record
ord-3b3f489067184e768192308f014c75c4
Source dataset
uspto-grants-1989_08
Patent number
US04853410

Reaction notes

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