From N-H Nitration to Controllable Aromatic Mononitration and Dinitration-The Discovery of a Versatile and Powerful N-Nitropyrazole Nitrating Reagent was written by Yang, Tao;Li, Xiaoqian;Deng, Shuang;Qi, Xiaotian;Cong, Hengjiang;Cheng, Hong-Gang;Shi, Liangwei;Zhou, Qianghui;Zhuang, Lin. And the article was included in JACS Au in 2022.Formula: C4H5N3O2 This article mentions the following:
Herein,the identification of a powerful nitrating reagent, 5-methyl-1,3-dinitro-1H-pyrazole, from the N-nitro-type reagent library constructed using a practical N-H nitration method was reported. This nitrating reagent behaved as a controllable source of the nitronium ion, enabling mild and scalable nitration of a broad range of (hetero)arenes with good functional group tolerance. Of note, this nitration method was controlled by manipulating the reaction conditions to furnish mononitrated or dinitrated product selectively. The value of this method in medicinal chem. was well established by its efficient late-stage C-H nitration of complex biorelevant mols. D. functional theory (DFT) calculations and preliminary mechanistic studies reveal that the powerfulness and versatility of this nitrating reagent were due to the synergistic “nitro effect” and “methyl effect”. In the experiment, the researchers used many compounds, for example, 3-Methyl-4-nitro-1H-pyrazole (cas: 5334-39-4Formula: C4H5N3O2).
3-Methyl-4-nitro-1H-pyrazole (cas: 5334-39-4) belongs to pyrazole derivatives. The 1H-pyrazole provides an excellent means by which to provide the requisite hydrogen bond acceptor–donor motifs, whether as a monocyclic ring or as a fused indazole ring. The pyrazole ring is resistant to oxidation and reduction but the groups, such as alkyl and formyl attached to the ring, are oxidized to respective acids. Only electrolytic oxidation, ozonolysis, and a strong base cause ring opening.Formula: C4H5N3O2
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics