Recent Advances in the Transition-Metal-Free Arylation of Hetero­arenes

Transition-metal-free arylation reactions have attracted considerable attention for economic and environmental reasons over the past 40 years. In recent years, much effort has been made to develop efficient transition-metal-free approaches for the arylation of heteroarenes. Covering the literature from 2015 to early 2021, this review aims to provide a thorough overview of the synthetic and mechanistic aspects of these atom-economical and environmentally benign reactions. 1 Introduction 2 Arylation of Pre-functionalized Heteroarenes 2.1 Arylation of Heteroaryl Halides 2.2 Decarboxylative Arylation of Heteroarenes 3 Direct C–H Arylation of Heteroarenes 3.1 C(sp2)–H Arylation 3.2 C(sp3)–H Arylation 4 N-Arylation of Heteroarenes 5 Summary and Outlook