Modern strategies for C-H functionalization of heteroarenes with alternative coupling partners

Heteroarenes containing oxygen, nitrogen, and/or sulfur are important in numerous aspects of chemistry and everyday life. C-H functionalization of heteroarenes represents the fastest and most atom- economical approach for the synthesis of complex molecules. This strategy avoids the requirement of de novo synthesis and is beneficial for the late-stage modification of structurally complex molecules. Although early protocols for C-H functionalization using organic halides (I, Br, and Cl) as coupling partners remain in active use today, a range of modern strategies allows the cleavage of less reactive C-Het (F, O, S, N, and P) and C-C bonds to form essential links to the feedstock chemicals, highlighting their renewable and sustainable features. This review focuses on modern strategies for the C-H functionalization of heteroarenes with these alternative coupling partners. Most of the transformations can be achieved through catalytic processes. Some non-catalytic strategies involving new reagents and techniques are also introduced.