Triethyl phosphite → 5-Bromo-6-chlorobenzo[c][1,2,5]oxadiazole

HRID 1468967Notes

Reaction equation

HRID 1468967 reaction equation
[Br:1][C:2]1[C:3]([Cl:12])=[CH:4][C:5]2[C:6]([CH:11]=1)=[N+:7]([O-])[O:8][N:9]=2.P(OCC)(OCC)OCC>C(O)C>[Br:1][C:2]1[C:3]([Cl:12])=[CH:4][C:5]2=[N:9][O:8][N:7]=[C:6]2[CH:11]=1

Participants

4

Reactant 2

HCID 31215Triethyl phosphiteHCID 674650696-Bromo-5-chlorobenzo[c][1,2,5]oxadiazole 1-oxide

Product 1

HCID 674684685-Bromo-6-chlorobenzo[c][1,2,5]oxadiazoleYield 79%

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent

Procedure

6-Bromo-5-chlorobenzo[c][1,2,5]oxadiazole 1-oxide (4.8 g, 19 mmol) was taken up 150 ml ethanol, heated to reflux, treated with triethyl phosphite (8.8 g, 53 mmol) and heated for 3.5 h. After cooling, the volatiles were removed by rotary evaporation, the residue was taken up in 100 mL dichloromethane and stirred with 50 mL bleach solution for 30 min. The organic phase was washed with 20 mL saturated NaCl, dried (Na2SO4) and evaporated. The crude material was purified by flash chromatography with a 0-30% ethyl acetate-hexane gradient to give the title compound as an orange solid (3.5 g, 79%): mp 68-69° C.; 1H NMR (400 MHz, CDCl3) δ 8.30 (s, 1H), 8.05 (s, 1H); EIMS m/z 232.

Workup

  1. temperatureheated
  2. temperatureto reflux
  3. temperatureheated for 3.5 h
  4. temperatureAfter cooling
  5. customthe volatiles were removed by rotary evaporation
  6. washThe organic phase was washed with 20 mL saturated NaCl
  7. dry with materialdried (Na2SO4)
  8. customevaporated
  9. customThe crude material was purified by flash chromatography with a 0-30% ethyl acetate-hexane gradient

Sources & evidence

ORD record
ord-dd4ba333b7224aa28c5526d6bbc0aadb
Source dataset
uspto-grants-2015_04
Patent number
US09006250B2

Reaction notes

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