1. INTRODUCTION In the last 139 years, 1 the pyrazole nucleus has been and somehow
remains a challenge for the design of selective synthesis. With five centers featuring different …

Pyrazoles are considered privileged scaffolds in medicinal chemistry. Previous reviews have
discussed the importance of pyrazoles and their biological activities; however, few have …

Silica-supported palladium phosphine complexes were prepared for alkoxycarbonylation
and aminocarbonylation of aryl iodides. These catalysts were highly efficient for the …

A copper-catalyzed [4+ 1] annulation between α-hydroxy ketones and nitriles has been
developed. The reaction provides a facile and efficient method for the construction of a wide …

Pyrazoles are five membered heterocycles constitute a higly significant class of compounds
in organic synthesis. Nowadays, pyrazoles and condensed pyrazoles have attracted …

A Michael equilibration model is presented to provide for site-selective pyrazole
condensations between alkoxyacrylonitriles and hydrazines. Both pyrazole isomers were …

The synthesis of differentially-substituted 3, 5-bis (arylamino) pyrazoles has not yet been
documented. During our investigation, we managed to develop a novel, entirely …

Pyranones fused with a pyrazolopyrimidine moiety were prepared via regioselective
construction of pyranone ring using (Pd/C-mediated) coupling–iodocyclization followed by …

A concise, environmentally benign, and cost-effective route was developed for the large-
scale preparation of 1, a novel oxazolidinone antibacterial candidate. The key intermediate …

Publisher Summary This chapter presents the synthesis and chemistry of five membered
heterocyclic ring systems containing more than one nitrogen atom, such as pyrazoles …