High‐Valent‐Cobalt‐Catalyzed C−H Functionalization Based on Concerted Metalation–Deprotonation and Single‐Electron‐Transfer Mechanisms

Abstract

C−H functionalization has been established as a powerful strategy for the commercial construction of organic molecules. This review encompasses the most recent advances in C−H activation catalyzed by earth‐abundant cobalt complexes, involving two types of fundamental reaction paths, that is, the concerted metalation–deprotonation (CMD) path associated with non‐oxidative C−H activation and the intermolecular single‐electron‐transfer (SET) path. Transformations catalyzed by high‐valent cobalt based on the two mechanisms and used in organic syntheses, including those involving C−C and C−X (X=O and N) bond formation, are herein presented.

Pivalophenone imine as a benzonitrile surrogate for directed C–H bond functionalization

“…Building on the above background, we have found that pivalophenone N–H imine serves as a benzonitrile surrogate for directed C–H functionalization reactions under cobalt catalysis, 19 which is reported herein. Thus, the tert -butyl N–H imine group smoothly directs cobalt-catalyzed C–H alkylation 13 and arylation 20 with the corresponding organic halides, and then readily undergoes fragmentation into a cyano group under peroxide photolysis or aerobic copper catalysis ( Scheme 2c ).…”

Mechanistic insights into the SN2-type reactivity of aryl-Co(iii) masked-carbenes for C–C bond forming transformations

“…Two different approaches coexist in the field of Co-catalyzed C–H functionalization: the low-valent approach, 22 , 23 which has been extensively studied, and the high-valent approach. 24 …”

Silver-Mediated Methoxylation of Aryl C(sp2)–H Bonds Directing by DMEDA

“…Alkyl aryl ethers are ubiquitous structural motifs present in both natural and synthetic compounds, particularly in bioactive molecules targeted as pharmaceuticals (Scheme 1) [1,2]. Compared to the traditional method for carbon-oxygen bond coupling [3][4][5][6], transition metal catalyzed C-H alkoxylation with alcohols has received much attention in recent decades in terms of atom and step economy [7][8][9][10]. However, direct C-H bond alkoxylation has been mostly limited to a palladium- [11][12][13][14][15] or copper-catalyzed system [16][17][18][19][20] which are both more biological toxicity metals.…”