Direct Arylation of C(sp2)–H Bonds in Anilines

Anilines selectively arylated at their ortho, meta or para positions are useful building blocks in synthesis and have found applications in many areas. The most straightforward method for their synthesis relies on the direct arylation of a C(sp2)–H bond of anilines, an attractive strategy avoiding the prefunctionalization of the starting anilines provided that such arylations proceed with high levels of regioselectivity. Such reactions are presented and discussed, in a comprehensive manner, in this review article, with an emphasis on the regioselectivity of the processes and factors governing both the reactivity and selectivity. 1 Introduction 2 ortho-Arylation of Anilines 2.1 Direct C(sp2)–H ortho-Arylation of Anilines 2.2 Directed C(sp2)–H ortho-Arylation of Anilines 3 meta-Arylation of Anilines 4 para-Arylation of Anilines 4.1 Direct C(sp2)–H para-Arylation of Anilines via Oxidative Radical Homodimerization 4.2 Direct C(sp2)–H para-Arylation of Anilines via Transition-Metal Catalysis 5 Conclusion and Outlook