BX 3 ‐Mediated Arene Borylation: Concepts, Scope, and Mechanistic Insight

ABSTRACT Transition metal‐free arene C‒H borylation has emerged as a promising strategy for the synthesis of arylborane compounds under mild, sustainable, and cost‐effective conditions, thus avoiding the limitations associated with precious metal‐catalyzed reactions. Central to these approaches is the use of highly electrophilic boron trihalides, which directly interact with the π‐electron systems of arenes to facilitate efficient borylation. This review article provides a critical analysis of the mechanistic pathways underlying such metal‐free transformations, with a particular emphasis on the elementary steps involved in the BX 3 ‐mediated C–H bond functionalization of arenes. Our discussion provides a conceptual framework to support both the interpretation of existing studies and the rational design of future methodologies in metal‐free borylation chemistry.