Design of new N-polyether pyrazole derived ligands: synthesis, characterization and regioselectivity was written by Guerrero, Miguel;Perez, Jose A.;Ros, Josep;Branchadell, Vicenc;Pellicer, Eva;Sort, Jordi;Pons, Josefina. And the article was included in Current Organic Synthesis in 2014.Quality Control of 2-(5-Methyl-1H-pyrazol-3-yl)pyridine This article mentions the following:
In this paper, for the first time the synthesis in satisfactory yields and characterization of a new family of five N-polyetheralkyl- 3,5-pyrazole derived ligands I (R1 = R2 = 2-Py, Ph; R2 = CH3) as well as regioselectivity studies by NMR techniques is presented. Ligands I (R1 = R2 = 2-Py, Ph; R2 = CH3) were obtained by N-alkylation reaction, whereas for I (R1 = 2-Py; R2 = Me) O-alkylation reaction was followed. In N-alkylation, the alkylating agent was 1-chloro-2-[2-(2-methoxyethoxy)ethoxy]ethane, NaOEt as base and dry toluene as solvent. In O-alkylation, the alkylating agent is 1- chloro-2-[2-(2-methoxyethoxy)ethoxy]ethane, metallic Na as a base and dry tetrahydrofurane as solvent. In general, the two methods lead to high yields (60-95%), with reaction times of 24 h, except for I (R1 = R2 = 2-Py) 48 h. Furthermore, the different regioselectivity observed in the synthetic reactions of pyrazole precursors with one pyridyl substituent has been rationalized from theor. calculations All together proves that the different behavior depends on whether the rate determining step is the SN2 reaction or the formation of the precursor complexes between pyrazolide-Na+ chelates and the polyether chloride chain. The application of this new family in supramol. crystal engineering is interesting due to the different bonding properties of the heteroatoms (N vs. O) present in the structure of the ligands. In the experiment, the researchers used many compounds, for example, 2-(5-Methyl-1H-pyrazol-3-yl)pyridine (cas: 19959-77-4Quality Control of 2-(5-Methyl-1H-pyrazol-3-yl)pyridine).
2-(5-Methyl-1H-pyrazol-3-yl)pyridine (cas: 19959-77-4) 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. Pyrazoles can be selectively lithiated at different carbons and subsequently react with electrophiles depending on the substitution patterns.Quality Control of 2-(5-Methyl-1H-pyrazol-3-yl)pyridine
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics