Acetic Anhydride → 8-Bromo-2H-1-benzopyran-3(4H)-one

HRID 1464690Notes

Reaction equation

HRID 1464690 reaction equation
[Br:1][C:2]1[CH:3]=[CH:4][CH:5]=[C:6]2[C:11]=1[O:10][CH2:9][CH:8]([OH:12])[CH2:7]2.O=P12OP3(OP(OP(O3)(O1)=O)(=O)O2)=O.O1C2C(=CC=CC=2)CCC1O.C(OC(=O)C)(=O)C>C(Cl)Cl.N1C=CC=CC=1>[Br:1][C:2]1[CH:3]=[CH:4][CH:5]=[C:6]2[C:11]=1[O:10][CH2:9][C:8](=[O:12])[CH2:7]2

Participants

7

Reactant 4

HCID 7918Acetic AnhydrideHCID 14812Phosphorus oxide (P4O10)HCID 11171070Chroman-2-olHCID 190871458-Bromochroman-3-ol

Product 1

HCID 190871488-Bromo-2H-1-benzopyran-3(4H)-one

Reagents, catalysts & solvents 2

HCID 1049PyridineSolventHCID 6344DichloromethaneSolvent

Procedure

The 8-bromo-3-chromanol was oxidized in small portions (400 mg, 1.7 mmol) in order to achieve better total yields. Dry pyridine (1.1 ml) was added to CH2Cl2 (60 ml), dried over P2O5 and CrO3 (0.69 g, 6.9 mmol) and molecular sieves were added to that solution. After 15 min the chromanol was added together with acetic anhydride (0.66 ml). The mixture was stirred for 10 min and then passed with suction through a column containing SiO2 (10 g), eluting with CH2Cl2. The collected eluate was evaporated and toluene was added after each evaporation (2-3 times), leaving the pure 8-bromo-3-chromanone (200 mg). GC/MS showed M+ /M+2 at m/e=226.25(89%)/228.25(82%).

Workup

  1. additionwere added to that solution
  2. washeluting with CH2Cl2
  3. customThe collected eluate was evaporated
  4. additiontoluene was added
  5. customafter each evaporation (2-3 times)

Sources & evidence

ORD record
ord-0f9ed010f26446d4979432ce2102533a
Source dataset
uspto-grants-1994_04
Patent number
US05306830

Reaction notes

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