Reacción #48034

Ecuación de reacción

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

styrene

triethylamine

→

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

Rendimiento 94.0%

Disolventes

benzene

Condiciones de reacción

Tratamiento posterior

1. 1
   Temperaturathe resulting solution is heated
2. 2
   Temperaturaat reflux temperature for 1 hour
3. 3
   Otrothe formed precipitate is removed by filtration
4. 4
   Lavadowashed with toluene
5. 5
   ConcentraciónThe filtrate is concentrated in vacuo
6. 6
   Otropurified by flash chromatography (silica gel, dichloromethane)

Procedimiento

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).

Fuente