Hydrochloric Acid → 6-fluoro-4-cyano-2H-benzopyran

HRID 2248282Notes

Reaction equation

HRID 2248282 reaction equation
[F:1][C:2]1[CH:3]=[CH:4][C:5]2[O:10][CH2:9][CH2:8][C:7]([C:16]#[N:17])(O[Si](C)(C)C)[C:6]=2[CH:18]=1.P(Cl)(Cl)(Cl)=O.Cl>N1C=CC=CC=1.O>[F:1][C:2]1[CH:3]=[CH:4][C:5]2[O:10][CH2:9][CH:8]=[C:7]([C:16]#[N:17])[C:6]=2[CH:18]=1

Participants

6

Reactant 3

HCID 313Hydrochloric AcidHCID 24813Phosphorus oxychlorideHCID 143394296-fluoro-2,3-dihydro-4-cyano-4-[(trimethylsilyl)oxy]-4H-benzopyran

Product 1

HCID 149865356-fluoro-4-cyano-2H-benzopyranYield 76.6%

Reagents, catalysts & solvents 2

HCID 962WaterSolventHCID 1049PyridineSolvent

Procedure

To a solution of 32 g (0.12 mole) of the crude 6-fluoro-2,3-dihydro-4-cyano-4-[(trimethylsilyl)oxy-]4H-benzopyran in 170 ml of dry pyridine was added 60 ml (0.6 mole) of phosphorous oxychloride. The reaction was heated to reflux for 5 hours then cooled to room temperature. The resulting solution was added dropwise to a solution of 300 cc of concentrated HCl in 1 L of water. This aqueous layer was extracted with EtOAc and the EtOAc layer was dried over Na2SO4, filtered and evaporated to give 16.1 g of product m.p. 114°-115° C. NMR (CDCl3) ppm (delta) 5.00 (d, 2H, J=4 Hz), 6.6-7.3 (m, 4H).

Workup

  1. temperatureThe reaction was heated
  2. temperatureto reflux for 5 hours
  3. extractionThis aqueous layer was extracted with EtOAc
  4. dry with materialthe EtOAc layer was dried over Na2SO4
  5. filtrationfiltered
  6. customevaporated

Sources & evidence

ORD record
ord-ee576f9aa58d4b8dabbd8a4347f21f5a
Source dataset
uspto-grants-1991_08
Patent number
US05039672

Reaction notes

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