Efficient Approaches to Six-Membered Polyazacyclic Compounds—Part 3: C—H Functionalization of Heterocycles

The review summarizes the literature data on the C-H functionalization of six-membered polyaza heterocycles, specifically diazine and triazine skeletons, which are important in medicine and pharmacology, as examples. The analysis covers the works published mainly over the last 20 years. The review focuses on strategies involving the use of transition metal-based catalysts or organic oxidants, where the nature of the <i>N</i>-heterocycles and the substrate molecules can be exploited to control regioselectivity. Each of these strategies has certain advantages as well as serious disadvantages and limitations. In addition to the experimental procedures, mechanistic schemes are discussed to provide a deeper understanding of the reactions described. The material presented allows us to draw the unambiguous conclusion that C-H bond functionalization processes are of crucial importance in the synthesis of molecules that exhibit a wide range of biological activity.