Beyond Friedel and Crafts: Innate Alkylation of C-H Bonds in Arenes

Abstract

Alkylated arenes are ubiquitous molecules and building blocks commonly utilized in most areas of science. Despite its apparent simplicity, the regioselective alkylation of arenes is still a challenging transformation in a lot of cases. Classical methods for the introduction of alkyl groups to arenes, such as the venerable Friedel-Crafts reaction, radical additions, metalation or prefunctionalization of the arene followed by further alkylation, as well as alternatives such as the directed alkylation of C-H bonds, still suffer from severe limitations in terms of scope, efficiency, and selectivity. This can be addressed by exploiting the innate reactivity of some (hetero)arenes, in which electronic and steric properties, governed (or not) by the presence of one (or multiple) heteroatom(s), ensure high levels of regioselectivity. These innate alkylations of C-H bonds in (hetero)arenes will be overviewed comprehensively in this Review.

Keywords: C−H activation; alkylation; arenes; heteroarenes; homogeneous catalysis.