Calcium carbide as the acetylide source: transition-metal-free synthesis of substituted pyrazoles via [1,5]-sigmatropic rearrangements was written by Yu, Yue;Huang, Wei;Chen, Yang;Gao, Bingjie;Wu, Wanqing;Jiang, Huanfeng. And the article was included in Green Chemistry in 2016.Recommanded Product: 3-(1H-Pyrazol-3-yl)pyridine This article mentions the following:
Under transition-metal-free conditions, N-tosylhydrazones derived from aldehydes or ketones were reacted with an acetylide source, calcium carbide to afford 3-substituted pyrazoles I [R1 = C6H5, 3-BrC6H4, H4C6(CH2)2, 2-thienyl, etc.; R2 = H] and 3,4-disubstituted pyrazoles I [R1 = Me, Et, n-Pr, C6H5; R2 = C6H5, 4-F3CC6H4, 2-naphthyl, etc.] resp. in good yields with high regioselectivities. The results of deuterium-labeling experiments indicated that these reactions proceed through [3 + 2] cycloadditions followed by [1,5]-sigmatropic rearrangements. In the experiment, the researchers used many compounds, for example, 3-(1H-Pyrazol-3-yl)pyridine (cas: 45887-08-9Recommanded Product: 3-(1H-Pyrazol-3-yl)pyridine).
3-(1H-Pyrazol-3-yl)pyridine (cas: 45887-08-9) belongs to pyrazole derivatives. An alternative way to synthesize multisubstituted pyrazoles is the Csingle bondH arylation of simple pyrazoles. Protonation of pyrazole in strong acid leads to pyrazolium cations, which undergo electrophilic substitution preferentially at C3 rather than C4. The pyrazole anion is not reactive toward nucleophiles but is mostly reactive to electrophiles.Recommanded Product: 3-(1H-Pyrazol-3-yl)pyridine
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics