QuederJ

A nickel catalyzed electrochemical cross-electrophile coupling approach for the base-free synthesis of (un)symmetric (hetero)aryl and alkyl sulfides from organic halides and disulfides is described. The reaction is broadly applicable and tolerates water and air atmosphere.

A formal cross-electrophile coupling approach enables the base-free synthesis of (un)symmetric (hetero)aryl and alkyl sulfides from organic halides and disulfides. This water and air-tolerant process utilizes the addition of electrochemically generated thiolate to an in situ-generated reactive nickel species.

Herein, we report the use of bis(trimethylaluminum)-1,4-diazabicyclo[2.2.2]octane (DABAl-Me₃) as practical source of radicals for the introduction of valuable methyl groups to aryl bromides via a Nickel/metallaphotocatalytic cross coupling strategy.

Abstract

We report a metallaphotocatalytic strategy for the selective methylation of (hetero)aryl bromides via nickel-catalyzed cross-coupling with bis(trimethylaluminum)-1,4-diazabicyclo[2.2.2]octane (DABAl-Me₃), as a commercially available, air-stable, and non-pyrophoric aluminum-based reagent. The method enables a fast, robust, and scalable methylation protocol that broadly accommodates various functional groups while preventing protodehalogenation. Mechanistic studies confirm the unprecedented generation of methyl radicals from an organo-aluminum precursor under photoredox conditions, bypassing the limitations of conventional two-electron pathways. This work expands the toolbox of practical radical precursors and provides a streamlined approach for selective C(sp²)─CH₃ bond formation.

A photoredox/nickel dual-catalyzed enantioselective decarboxylative acylation of α-hydroxy acid derivatives with carboxylic acids has been developed, enabling efficient access to enantioenriched α-oxygenated ketones. This method exhibits a broad substrate scope, good functional group tolerance, high chemoselectivity, and excellent enantioselectivity.

Abstract

Light-driven decarboxylative cross-coupling has emerged as a pivotal platform for constructing C(sp³)–C(sp²) bonds in organic synthesis and medicinal chemistry. However, using two structurally dissimilar carboxylic acids as a feedstock to form chiral α-oxygenated ketones remains a considerable challenge due to side reactions such as decarboxylative reduction and homocoupling. Herein, we report for the first time a photoredox/nickel dual-catalyzed enantioselective decarboxylative acylation of α-hydroxy acid derivatives and aliphatic carboxylic acids, enabling efficient access to enantioenriched α-oxygenated ketones. This method exhibits a broad substrate scope, good functional group tolerance, high chemoselectivity, and excellent enantioselectivity (up to 99% e.e.). The advantage of this reaction is that it eliminates the need for metal reductants and the use of precious metal photocatalysts and utilizes renewable feedstocks. The use of a coiled-tube continuous-flow photoreactor can shorten the illumination time by half and obtain results comparable to those of a batch reaction. Furthermore, preliminary mechanistic experiments support a pathway in which photocatalytic decarboxylation generates α-oxy alkyl radical species, and the Ni(I)–alkyl intermediate activates the in situ–formed mixed anhydride followed by reductive elimination to give the product in enantiomerically pure form.

YES WE CAN—the electrochemical iodination of electron-deficient arenes under Lewis acid-free conditions in a divided cell is realized when Bu₄NI as pre-reagent is oxidised at the anode and catalytic amounts of Bu₄NCl are present for the generation of [I₂Cl]⁺ as active iodinating agent. The iodination is capable to convert a wide range of interesting halogenated arenes, aromatic aldehydes, benzoic acids, benzoates, aryl nitriles, aryl ketones and nitrobenzene derivatives into their corresponding iodinated products.

Abstract

The iodination of electron-deficient arenes and heteroarenes is a long-standing problem in organic synthesis. Herein we describe the electrochemical iodination in nitromethane with Bu₄NI as iodine source and supporting electrolyte under Lewis acid-free conditions in the presence of small amounts of chloride anions. The electrochemically generated reagent could be applied for the iodination of halogenated arenes, aromatic aldehydes, acids, esters, ketones, as well as nitroarenes to afford the products in good to excellent yields.

Molecules, Vol. 29, Pages 4669: Electrochemical Nickel-Catalyzed Synthesis of Unsymmetrical Diorganyl Selanes from Diaryl Diselanes and Aryl and Alkyl Iodides

Molecules doi: 10.3390/molecules29194669

Authors: Jona Queder Gerhard Hilt

The synthesis of unsymmetrical diorganyl selanes was accomplished under electrochemical conditions in an undivided cell utilizing a magnesium cathode and a carbon anode made out of aryl and alkyl iodides and diselanes. This electrochemical cross-electrophile coupling (eXEC) was accomplished using a simple nickel catalyst formed in situ out of Ni(acac)2 and 2,2′-bipyridine in DMF at ambient temperatures. The reaction showed good functional group compatibility, and heteroaryl iodides, such as thiophene or pyridine derivatives, were well accepted.