Remote ortho-C–H functionalization via medium-sized cyclopalladation

Abstract

Remote ortho-C–H bond activation via seven- or eight-membered metalacycles is particularly challenging and remains rare. This highlight provides an overview of recent advances using palladium catalysis, with an emphasis on mechanistic details.

OrthoC−H Functionalizations of 2‐Aryl‐2H‐Indazoles

“…Recently, directed site-selective CÀ H functionalization is getting immense interest due to providing a go-to general method for installing various functional groups at a particular position of a heterocycle. [12] Depending on the length and structure of directing group or template and formation of metallacyclic intermediate, ortho-, [13] meta-, [14] and even para-selective CÀ H bond activations and functionalizations [15] can be easily attainable. Among them, ortho CÀ H functionalization is largely expanded as it generally advances through five to sevenmembered metallacyclic intermediates.…”

Native carboxyl group-assisted C–H acetoxylation of hydrocinnamic and phenylacetic acids

“…In the past few decades, enormous advances have been achieved in transition-metal-catalyzed C–H activation reactions. 1 However, these reactions often require extra steps for the installation and removal of exogenous directing groups. 1 Therefore, the C–H transformation methods that could use native directing groups would be more practical due to the higher step and atom economy of these reactions.…”

“…1 However, these reactions often require extra steps for the installation and removal of exogenous directing groups. 1 Therefore, the C–H transformation methods that could use native directing groups would be more practical due to the higher step and atom economy of these reactions. 1 d ,2 However, it is still challenging to develop C–H activation reactions by taking advantage of native directing groups due to various reasons, including incompatible chelation ability or unsuitable distance to form the required metallacycles.…”

Azobenzene-based unnatural amino acid scaffolds via a Pd(ii)-catalyzed C(sp3)–H arylation strategy

“…Transition metal-catalyzed sp 3 C–H bond functionalization reactions have received paramount attention in recent years. 1–3 Particularly, Pd( ii )-catalyzed, directing group-aided site-selective C–H functionalization has emerged as a valuable method. 2,3 This method has also enabled the diastereoselective functionalization of prochiral C(sp 3 )–H bonds of aliphatic compounds.…”

“…2,3 This method has also enabled the diastereoselective functionalization of prochiral C(sp 3 )–H bonds of aliphatic compounds. 2,3…”