Design of Organic Radical Cations as Potent Hydrogen‐Atom Transfer Catalysts for C−H Functionalization

Abstract

Hydrogen‐atom transfer (HAT) catalysis offers an atom‐ and step‐economical approach to the direct functionalization of aliphatic C–H bonds. While the structure of HAT catalysts largely affects the reactivity and selectivity in the step where the C–H bond is cleaved, the choice of viable catalysts for HAT from strong C–H bonds is limited. The recent development of organic HAT catalysts based on the flexibly modifiable molecular platform has enabled fine‐tuning of the steric and electronic properties of these catalysts, thus greatly expanding their structural diversity. This review focuses on the design of HAT catalysts with cationic moieties as common structural motifs and their application to the selective manipulation of the C–H bonds of challenging substrates, including unactivated hydrocarbons.

Electrochemical Heteroarylation and Amidation of Alkanes using Activated Glassy Carbon Electrodes without Mediators

“…Among them, catalytic and tunable hydrogen atom transfer (HAT) agents have emerged to homolytically break different C-H bonds to generate the C-centered radical in the last few decades. 5 In this regard, we recently described a photocatalyzed strategy to perform Minisci-type reactions using pyridine Noxides as HAT species (BDE (PyO-H), 99 kcal/mol), which effectively abstracted a hydrogen atom from a variety of alkanes, ethers, and amides among others. 6 Following our interest in the Minisci reaction and developing more sustainable methodologies, we sought to investigate electrocatalysis in this oxidative cross-dehydrogenative coupling (CDC), which would avoid the addition of any external chemical oxidant and the formation of chemical waste (Figure 1D).…”