Orientation of the alkylation reaction of pyrazoles under neutral conditions and in phase-transfer catalysis was written by Tarrago, Georges;Ramdani, Abdelkrim;Elguero, Jose;Espada, Modesta. And the article was included in Journal of Heterocyclic Chemistry in 1980.Application of 19959-77-4 This article mentions the following:
The N-butylation and N-benzylation of nine pyrazoles bearing different substituents in positions 3 and 5 have been studied in neutral and basic medium (phase transfer catalysis). The orientation of the reaction depends strongly on the method used when the position 3 (or 5) of the starting pyrazole bears a substituent with a lone pair in the ortho position (pyrazolyl or pyridyl). In the experiment, the researchers used many compounds, for example, 2-(5-Methyl-1H-pyrazol-3-yl)pyridine (cas: 19959-77-4Application of 19959-77-4).
2-(5-Methyl-1H-pyrazol-3-yl)pyridine (cas: 19959-77-4) belongs to pyrazole derivatives. Pyrazoles, a five-membered heterocycle containing two adjacent nitrogen atoms, are the core structures found in a number of molecules that possess a wide range of pharmaceutical and agricultural activities. 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 19959-77-4
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics