Reaktion #6978

Reaktionsgleichung

nitric acid

H2SO4

4-fluorobenzenesulfonyl chloride

DIPEA

citric acid

cyclopropylamine

→

N-cyclopropyl-4-fluoro-3-nitrobenzenesulfonamide

Ausbeute 92.0%

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONpoured
2. 2
   Extraktionextracted with dichloromethane (2×)
3. 3
   WaschenThe organic layer was washed with brine
4. 4
   Trocknendried over Na2SO4
5. 5
   Filtrationfiltered
6. 6
   Einengenconcentrated
7. 7
   workup.DISSOLUTIONThe residue was dissolved in CH2Cl2 (30 mL)
8. 8
   Temperaturcooled to −40° C.
9. 9
   workup.ADDITIONwere added
10. 10
    workup.STIRRINGAfter stirring at −40° C. for 2 h
11. 11
    Extraktionextracted with dichloromethane
12. 12
    SonstigeThe organic layer was separated
13. 13
    Einengenconcentrated in vacuo

Vorschrift

To a solution of fuming nitric acid (8 mL) and conc. H2SO4 (16 mL), was added 4-fluorobenzenesulfonyl chloride (1.3 g, 6.7 mmol) in small portions. The mixture was stirred at RT for 2 h. and then poured onto crushed ice (60 g) and extracted with dichloromethane (2×). The organic layer was washed with brine, dried over Na2SO4, filtered and concentrated. The residue was dissolved in CH2Cl2 (30 mL) cooled to −40° C. and cyclopropylamine (388 mg, 6.8 mmol), followed by DIPEA (8 mmol) were added. After stirring at −40° C. for 2 h, the mixture was poured on 5% citric acid solution and extracted with dichloromethane. The organic layer was separated, and passed through a short pad of silica gel and concentrated in vacuo to afford N-cyclopropyl-4-fluoro-3-nitrobenzenesulfonamide (1.6 g, 92%) as a yellow solid.

Quelle