Reaktion #48034

Reaktionsgleichung

ethyl 2-chloro[(4-chlorophenyl) hydrazono]acetate

styrene

triethylamine

→

ethyl 1-(4-chlorophenyl)-5-phenyl-4,5-dihydro-(1H)-pyrazole-3-carboxylate

Ausbeute 94.0%

Lösungsmittel

benzene

Reaktionsbedingungen

Aufarbeitung

1. 1
   Temperaturthe resulting solution is heated
2. 2
   Temperaturat reflux temperature for 1 hour
3. 3
   Sonstigethe formed precipitate is removed by filtration
4. 4
   Waschenwashed with toluene
5. 5
   EinengenThe filtrate is concentrated in vacuo
6. 6
   Sonstigepurified by flash chromatography (silica gel, dichloromethane)

Vorschrift

Part B: To a stirred boiling solution of ethyl 2-chloro[(4-chlorophenyl) hydrazono]acetate (22.95 gram, 0.088 mol) and styrene (30.3 ml, 0.264 mol) in benzene (140 ml) is added triethylamine (34.3 ml, 0.247 mol) and the resulting solution is heated at reflux temperature for 1 hour. The resulting solution is cooled to room temperature and the formed precipitate is removed by filtration and washed with toluene. The filtrate is concentrated in vacuo and purified by flash chromatography (silica gel, dichloromethane) to give ethyl 1-(4-chlorophenyl)-5-phenyl-4,5-dihydro-(1H)-pyrazole-3-carboxylate (27.2 gram, 94% yield) as a syrup which slowly solidifies on standing. 1H-NMR (200 MHz, CDCl3): 1.38 (t, J=7 Hz, 3H), 3.06 (dd, J=18 and 7 Hz, 1H), 3.73 (dd, J=18 and 13 Hz, 1H), 4.33 (q, J=7 Hz, 2H), 5.38 (dd, J=13 and 7 Hz, 1H), 7.02 (br d, J=8 Hz, 2H), 7.08-7.40 (m, 7H).

Quelle