Approach to the library of fused pyridine-4-carboxylic acids by Combes-type reaction of acyl pyruvates and electron-rich amino heterocycles was written by Volochnyuk, Dmitriy M.;Ryabukhin, Sergey V.;Plaskon, Andrey S.;Dmytriv, Yuri V.;Grygorenko, Oleksandr O.;Mykhailiuk, Pavel K.;Krotko, Dmitriy G.;Pushechnikov, Alexei;Tolmachev, Andrey A.. And the article was included in Journal of Combinatorial Chemistry in 2010.Formula: C5H9N3 This article mentions the following:
A library of fused pyridine-4-carboxylic acids (including pyrazolo[3,4-b]pyridines, isoxazolo[5,4-b]pyridines, furo[2,3-b]pyridines, thieno[2,3-b]pyridines, and pyrido[2,3-d]pyrimidines) was generated by Combes-type reaction of acyl pyruvates and electron-rich amino heterocycles followed by hydrolysis of the ester. The library members were also demonstrated to undergo the standard combinatorial transformations including amide coupling and esterification, as well as less common heterocyclizations to 1,2,4-triazoles and 1,2,4-oxadiazoles. In the experiment, the researchers used many compounds, for example, 1-Ethyl-1H-pyrazol-5-amine (cas: 3528-58-3Formula: C5H9N3).
1-Ethyl-1H-pyrazol-5-amine (cas: 3528-58-3) 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. Pyrazole rings have been used as core components of several leading non-steroidal anti-inflammatory drugs (NSAIDs) and antihypertensive drugs. It has also been found to be useful as a bifunctional ligand for metal catalysis.Formula: C5H9N3
Referemce:
Pyrazole – Wikipedia,
Pyrazoles – an overview | ScienceDirect Topics