Site‐Selective CH Functionalizations Using Pd Catalysis and Photochemistry

Abstract

In organic synthesis, the selectivity of any transformation is considered to be the prime target. Since the past decade, site‐selective CH functionalizations are apprehended as one of the most promising areas where Pd‐catalyzed methods are predominant. For a long duration, organic chemists have enjoyed the benefits of Pd‐catalyzed cross‐coupling reactions and realized the pros and cons. Simultaneously, the need of palladium‐catalyzed methods for CH functionalization through CH bond activations was realized that led them to discover site‐selective ortho and proximal‐sp 3 CH functionalization. Eventually, this had pushed to achieve site‐selective distal sp 3 and meta / para ‐sp 2 CH functionalization methods. Different novel strategies including rational design of directing templates with different kinds of directing groups have been successfully utilized for proximal and distal CH functionalizations. Inherent drawbacks of such reactions further motivated the chemists to synergize with greener photoredox approaches to perform these reactions more sustainably. In this article, we have depicted all these different approaches of CH functionalization by Pd catalysis in a more concise and elucidated way.