Nitrogen → 1-(4-chlorophenyl)-5-phenyl-4,5-dihydro-(1H)-pyrazole-3-carboxamidine

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Reaction Steps

Part A: A stirred suspension of NH4Cl (2.68 g, 0.05 mol) in toluene (25 ml) is cooled to 0° C. in an N2 atmosphere. A solution of Me3Al in toluene (25 ml of a 2 M solution) is slowly added and the mixture is allowed to attain room temperature. A solution of ethyl 1-(4-chlorophenyl)-5-phenyl-4,5-dihydro-(1H)-pyrazole-3-carboxylate (3.29 gram, 10 mmol) in toluene (25 ml) is slowly added and the reaction mixture is stirred at 80° C. for 16 hours. After cooling to 0° C. methanol is slowly added and the formed precipitate is removed by filtration. The filtrate is concentrated and the residue is dissolved in a mixture of dichloromethane and methanol. The formed precipitate is removed by filtration. The filtrate is concentrated and the remaining residue crystallised from dichloromethane to give 1-(4-chlorophenyl)-5-phenyl-4,5-dihydro-(1H)-pyrazole-3-carboxamidine.HCl (2.70 g, 73% yield). 1H-NMR (200 MHz, DMSO-d6): 3.08 (dd, J=18 and 7 Hz, 1H), 3.82 (dd, J=18 and 13 Hz, 1H), 5.84 (dd, J=13 and 7 Hz, 1H), 7.15-7.46 (m, 9H), 8.85 (br s, 2H), 9.00 (br s, 2H).

Provenance & Evidence