Preparation of 1,3,5-trisubstituted pyrazoles with cascade reaction catalyzed by Cu between hydrazonoyl halide and terminal alkynes was written by Li, Fuwei;Wang, Xiaolong;Yu, Haitao. And the article was included in Youji Huaxue in 2016.Application of 17355-75-8 The following contents are mentioned in the article:
Cascade reaction, including nucleophilic substitution and addition cyclization, catalyzed by Cu+ salt between substituted aryl hydrazonoyl halides and terminal alkynes could produce 1,3,5-trisubstituted pyrazoles. The method employed easily available aryl hydrazonoyl halide and terminal alkynes as starting materials under 45°C in green acetonitrile/water solvent, regioselectively generating 1,3,5-trisubstituted pyrazoles in high yield. Above all, functional groups containing active hydrogen would not disturb this reaction, example for carboxyl and hydroxyl. In this work, 17 pyrazole derivatives with different substituent group were achieved by this method. So it could be a general method to synthesize 1,3,5-trisubstituted pyrazoles. This study involved multiple reactions and reactants, such as Ethyl 1,5-diphenyl-1H-pyrazole-3-carboxylate (cas: 17355-75-8Application of 17355-75-8).
Ethyl 1,5-diphenyl-1H-pyrazole-3-carboxylate (cas: 17355-75-8) belongs to pyrazole derivatives. Pyrazole has two ring nitrogen atoms in which N1 is pyrrolic and N2 is pyridine-like. The N1 nitrogen is not reactive but is deprotonated in the presence of a base-forming anion. The presence of both electronegative nitrogen atoms in the pyrazole ring reduces the electron density of the C3- and C5-positions leaving electron density of C4-position unaltered. Thus the C4-position is vulnerable to electrophilic attack. The C3 electrophilic-position may undergo deprotonation in the presence of a strong base leading to ring opening.Application of 17355-75-8
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics