Recent Developments in Transition-Metal Catalyzed Direct C–H Alkenylation, Alkylation, and Alkynylation of Azoles

The transition metal-catalyzed C–H bond functionalization of azoles has emerged as one of the most important strategies to decorate these biologically important scaffolds. Despite significant progress in the C–H functionalization of various heteroarenes, the regioselective alkylation and alkenylation of azoles are still arduous transformations in many cases. This review covers recent advances in the direct C–H alkenylation, alkylation and alkynylation of azoles utilizing transition metal-catalysis. Moreover, the limitations of different strategies, chemoselectivity and regioselectivity issues will be discussed in this review.