Reaktion #816428

Reaktionsgleichung

DMF

oxalyl chloride

oxalyl chloride

2-ethyl-4-hydroxy-5-phenylisothiazol-3(2H)-one 1,1-dioxide

DMF

2-Ethyl-4-hydroxy-5-phenylisothiazol-3(2H)-one 1,1-dioxide

→

title compound

4-Chloro-2-ethyl-5-phenylisothiazol-3(2H)-one 1,1-dioxide

Lösungsmittel

DCM

DCM

Reaktionsbedingungen

Aufarbeitung

1. 1
   SonstigeThe ice-bath was removed
2. 2
   Temperaturthe mixture was refluxed at 50° C. under N2 for 4 h
3. 3
   SonstigeThe reaction mixture was evaporated
4. 4
   workup.ADDITIONthe residue was diluted with EtOAc
5. 5
   Waschenwashed with water (3×25 mL) and brine
6. 6
   Trocknendried over Na2SO4
7. 7
   Sonstigeevaporated
8. 8
   Temperaturcooled to 0° C. under N2
9. 9
   SonstigeThe ice-bath was removed
10. 10
    Temperaturthe mixture was refluxed at 50° C. under N2 for 4 h
11. 11
    SonstigeThe reaction mixture was evaporated
12. 12
    workup.ADDITIONthe residue was diluted with EtOAc
13. 13
    Waschenwashed with water (3×50 mL) and brine
14. 14
    Trocknendried over Na2SO4
15. 15
    Sonstigeevaporated where by red solid
16. 16
    Sonstigewas obtained
17. 17
    Sonstigepurified by column chromatography on silica gel using 2.5-3% EtOAc in petroleum ether as eluant
18. 18
    Sonstigerecrystallised from MeOH

Vorschrift

2-Ethyl-4-hydroxy-5-phenylisothiazol-3(2H)-one 1,1-dioxide (5 g, 19.76 mmol) was dissolved in dry DCM (250 mL) and cooled to 0° C. under N2. Dry DMF (15 mL) was added, followed by oxalyl chloride (3 mL, 34.4 mmol). The ice-bath was removed and the mixture was refluxed at 50° C. under N2 for 4 h. The reaction mixture was evaporated and the residue was diluted with EtOAc and washed with water (3×25 mL) and brine, dried over Na2SO4 and evaporated. Another (16 g, 63.24 mmol) of 2-ethyl-4-hydroxy-5-phenylisothiazol-3(2H)-one 1,1-dioxide was dissolved in dry DCM (500 mL) and cooled to 0° C. under N2. Dry DMF (20 mL) was added followed by oxalyl chloride (9 mL, 103.2 mmol). The ice-bath was removed and the mixture was refluxed at 50° C. under N2 for 4 h. The reaction mixture was evaporated and the residue was diluted with EtOAc and washed with water (3×50 mL) and brine, dried over Na2SO4 and evaporated where by red solid was obtained. The crude material from both batches were combined and purified by column chromatography on silica gel using 2.5-3% EtOAc in petroleum ether as eluant, and recrystallised from MeOH to give the title compound (15.7 g, 70%) as a white solid; 1H NMR (400 MHz, CD3OD) δ 1.42 (t, 3H, J=7.3 Hz), 3.84 (q, 2H, J=7.3 Hz), 7.6-7.7 (m, 3H), 7.9-8.0 (m, 2H); Mass Spectrum: M+H+ 272.

Quelle