Thionyl Chloride → 5,6-difluoro-2,4-dihydro-1H-3,1-benzoxazine-2,4-dione

HRID 1378008Notes

Reaction equation

HRID 1378008 reaction equation
S(Cl)(Cl)=O.C([O:9][C:10]([NH:12][C:13]1[CH:21]=[CH:20][C:19]([F:22])=[C:18]([F:23])[C:14]=1[C:15]([OH:17])=[O:16])=O)(C)(C)C>O1CCCC1>[F:23][C:18]1[C:14]2[C:15](=[O:17])[O:16][C:10](=[O:9])[NH:12][C:13]=2[CH:21]=[CH:20][C:19]=1[F:22]

Participants

4

Reactant 2

HCID 24386Thionyl ChlorideHCID 229144216-((tert-Butoxycarbonyl)amino)-2,3-difluorobenzoic acid

Product 1

HCID 229144245,6-difluoro-2,4-dihydro-1H-3,1-benzoxazine-2,4-dioneYield 77.5%

Reagents, catalysts & solvents 1

HCID 8028TetrahydrofuranSolvent2×

Procedure

A solution of 108 ml of thionyl chloride in 300 ml of tetrahydrofuran was added dropwise while cooling with ice to a solution of 100 g (366 mmol) of 2-(tert.-butoxycarbonyl)amino-5,6-difluorobenzoic acid in 1.5 I of dry tetrahydrofuran, whereupon the mixture was stirred at room temperature for 16 hours. The brown solution was evaporated and the brown solid obtained was triturated with methylene chloride. The beige powder obtained was filtered off and dried in a high vacuum. There were obtained 56.5 g (77%) of 5,6-difluoro-2,4-dihydro-1H-3,1-benzoxazine-2,4-dione as a beige powder of m.p. >240°.

Workup

  1. customThe brown solution was evaporated
  2. customthe brown solid obtained
  3. customwas triturated with methylene chloride
  4. customThe beige powder obtained
  5. filtrationwas filtered off
  6. customdried in a high vacuum

Sources & evidence

ORD record
ord-67f724e6c1e6457ebc0811b18188936c
Source dataset
uspto-grants-1997_09
Patent number
US05665718

Reaction notes

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