Heterocycles play an important role in biochemical processes because the side groups of the most typical and essential constituents of living cells are based on aromatic heterocycles. The presence of heterocycles in biology, pharmacology, optics, electronics, etc. is very well known. Between them, sulfur and nitrogen-containing heterocyclic compounds have maintained the interest of researchers through the development of organic synthesis. Furthermore, azole antifungal agents are the largest class of antimycotics available today. Fused and pendent heterocyclic rings are a ubiquitous feature of many pharmaceutical products. Это и многое другое вы найдете в книге General description of heterocyclic derivatives (Nadia Salih,Jumat Salimon and Emad Yousif)