A Photoredox-Catalyzed Approach for Formal Hydride Abstraction to Enable Csp3–H Functionalization with Nucleophilic Partners

28 May 2021, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


While a great number of C–H functionalization methods have been developed in recent years, new mechanistic paradigms to deconstruct such bonds have been comparatively rare. Amongst possible strategies for breaking a Csp3–H bond are deprotonation, oxidative addition with a metal catalyst, direct insertion via a nitrene intermediate, hydrogen atom transfer (HAT) with both organic and metal-based abstractors, and lastly, hydride abstraction. The latter is a relatively unexplored approach due to the unfavorable thermodynamics of such an event, and thus has not been developed as a general way to target both activated and unactivated Csp3–H bonds on hydrocarbon substrates. Herein, we report our successful efforts in establishing a catalytic C–H functionalization manifold for accessing an intermediate carbocation by formally abstracting hydride from unactivated Csp3–H bonds. The novel catalytic design relies on a stepwise strategy driven by visible light photoredox catalysis and is demonstrated in the context of a C–H fluorination employing nucleophilic fluorine sources. Difluorination of methylene groups is also demonstrated, and represents the first C–H difluorination with nucleophilic fluoride. Additionally, the formal hydride abstraction is shown to be amenable to several other classes of nucleophiles, allowing for the construction of C–C or C–heteroatom bonds.


Photoredox Catalysis
Reaction Methodology
CH Functionalization
Nucleophilic Fluorination

Supplementary materials

SI-CH-nucleophilic fluorination-final


Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.