BN isosteres of indole.

Indole is a heterocycle of great importance to biological systems and materials applications. Synthesis of indole and its derivatives has been a major focus of research for over a century. BN/CC isosterism is an emerging strategy for expanding the structural diversity of indole-based compounds. Two classes of BN indoles have been reported to date: the well-studied "external" BN indoles (or 1,3,2-benzodiazaborolines), and the recently reported "fused" BN indoles. This perspective presents the history of both classes of indole isosteres, with a general overview of their synthesis, functionalization, and properties.