A Radical Process towards the Development of Transition‐Metal‐Free Aromatic CarbonCarbon Bond‐Forming Reactions

Abstract

Transition-metal-free cross-coupling reactions have been a hot topic in recent years. With the aid of a radical initiator, a number of unactivated arene C-H bonds can be directly arylated/functionalized by using aryl halides through homolytic aromatic substitution. Commercially available or specially designed promoters (e.g. diamines, diols, and amino alcohols) have been used to make this synthetically attractive method viable. This protocol offers an inexpensive, yet efficient route to aromatic C-C bond formations since transition metal catalysts and impurities can be avoided by using this reaction system. In this article, we focus on the significance of the reaction conditions (e.g. bases and promoters), which allow this type of reaction to proceed smoothly. Substrate scope limitations and challenges, as well as mechanistic discussion are also included.

A facile access for the C-N bond formation by transition metal-free oxidative coupling of benzylic C-H bonds and amides

“…Recently, transition-metal-free coupling protocols for biaryl synthesis have drawn widespread attention [45][46][47][48][49][50]. However, to the best of our knowledge, the metal-free direct oxidative C-H amination of Csp 3 -H bonds was mostly limited via hypervalent halogen compounds [51][52][53].…”

C–H Bond Activation for Arylations

“…It should be noted that radical initiators have come to the fore in recent times [6,7]. Two types of DGs are known: (i) nonoxidizing and (ii) oxidising (DG ox ).…”

Graphene Oxide Catalyzed C−H Bond Activation: The Importance of Oxygen Functional Groups for Biaryl Construction

“…[1] Originally,a rylation reactions,s uch as the Suzuki and Kumada couplings,a re based on traditional cross-coupling routes catalyzed by metal complexes.Apart from these waterand oxygen-sensitive reaction systems, [1] direct arylation reactions catalyzed by Pd, [2] Rh, [3] Ru, [4] and Ir [5] complexes have also been developed. [1] Originally,a rylation reactions,s uch as the Suzuki and Kumada couplings,a re based on traditional cross-coupling routes catalyzed by metal complexes.Apart from these waterand oxygen-sensitive reaction systems, [1] direct arylation reactions catalyzed by Pd, [2] Rh, [3] Ru, [4] and Ir [5] complexes have also been developed.…”