Cobalt-electrocatalytic C-H hydroxyalkylation of N-heteroarenes with trifluoromethyl ketones

Redox-Neutral Coupling of Allyl Alcohols with Trifluoromethyl Ketones via Synergistic Ni-Ti Bimetallic Catalysis

A redox-neutral coupling of allyl alcohols with trifluoromethyl ketones has been developed via Ni-Ti bimetallic catalysis. This innovative method allows for the efficient synthesis of various β-tertiary trifluoromethyl alcohol-substituted ketones with yields of up to 98%. The reaction is scalable and compatible with a wide range of substrates, including complex bioactive molecules. Mechanistic studies suggest that the rate-determining step involving β-H elimination and the presence of the Ti-based Lewis acid, as well as a hydroxyl group on the substrates, is crucial for driving the reactivity of this transformation.

When transition-metal catalysis meets electrosynthesis: a recent update

While aiming at sustainable synthesis, organic electrosynthesis has attracted increasing attention in the past few years. In parallel, with a deeper understanding of catalyst and ligand design, 3d transition-metal catalysis allows the conception of more straightforward synthetic routes in a cost-effective fashion. Owing to their intrinsic advantages, the merger of organic electrosynthesis with 3d transition-metal catalysis has offered huge opportunities for conceptually novel transformations while limiting ecological footprint. This review summarizes the key advancements in this direction published in the recent two years, with specific focus placed on strategy design and mechanistic aspects.

Cathodically Coupled Electrolysis to Access Biheteroaryls

An electrochemical approach to biheteroaryls through the coupling of diverse N-heteroarenes with heteroaryl phosphonium salts is reported. The reaction features pH and redox-neutral conditions and excellent regioselectivity, as well as exogenous air or moisture tolerance. Additionally, a one-pot, two-step protocol can be established to realize formal C-H/C-H coupling of heteroarenes, thereby greatly expanding the substrate availability. The utility of this method is demonstrated through late-stage functionalization, the total synthesis of nitraridine, and antifungal activity studies.

Direct alkylation of quinoxalinones with electron-deficient alkenes enabled by a sequential paired electrolysis

The metal-free alkylation of N-heterocycles with alkenes has remained a synthetic challenge. We report here the successful implementation of metal-free alkylation of quinoxalinones with electron-deficient alkenes enabled by a sequential paired electrolysis. This protocol provides a mechanistically distinct approach to prepare a variety of C-3 alkylated quinoxalinones that are otherwise quite difficult to synthesize by other means.

Access to Trifluoromethylketones from Alkyl Bromides and Trifluoroacetic Anhydride by Photocatalysis

Aliphatic trifluoromethyl ketones are a type of unique fluorine-containing subunit which play a significant role in altering the physical and biological properties of molecules. Catalytic methods to provide direct access to aliphatic trifluoromethyl ketones are highly desirable yet remain underdeveloped, partially owing to the high reactivity and instability of trifluoroacetyl radical. Herein, we report a photocatalytic synthesis of trifluoromethyl ketones from alkyl bromides with trifluoroacetic anhydride. The reaction features dual visible-light and halogen-atom-transfer catalysis, followed by an enabling radical-radical cross-coupling of an alkyl radical with a stabilized trifluoromethyl radical. The reaction provides straightforward access to aliphatic trifluoromethyl ketones from readily available and cost-effective alkyl halides and trifluoroacetic anhydride (TFAA).

Acceptorless cross-dehydrogenative coupling for C(sp3)-H heteroarylation mediated by a heterogeneous GaN/ketone photocatalyst/photosensitizer system

Alkanes are naturally abundant chemical building blocks that contain plentiful C(sp3)-H bonds. While inert, the activation of C(sp3)-H via hydrogen atom abstraction (HAT) stages an appealing approach to generate alkyl radicals. However, prevailing shortcomings include the excessive use of oxidants and alkanes that impede scope. We herein show the use of gallium nitride (GaN) as a non-toxic, recyclable, heterogeneous photocatalyst to enable alkyl C(sp3)-H in conjunction with the catalytic use of simple photosensitizer, benzophenone, to promote the desired alkyl radical generation. The dual photocatalytic cycle enables cross-dehydrogenative Minisci alkylation under mild and chemical oxidant-free conditions.

Catalyst-free C(sp3)-H functionalization of methyl azaarenes with heteroaromatic trifluoromethyl ketone hydrates: "all-water" synthesis of α-trifluoromethyl tertiary alcohols

An efficient catalyst-free C(sp³)-H bond functionalization of methyl azaarenes with heteroaromatic trifluoromethyl ketone hydrates in neat water has been developed for the synthesis of α-trifluoromethyl tertiary alcohols bearing N-heteroaromatics. This method not only features excellent efficiency, broad substrate scope, catalyst-free conditions, and easy gram-scale preparation but also represents a new and rare example of "all-water" synthesis of trifluoromethylated molecules.