Electrochemistry enabled selective vicinal fluorosulfenylation and fluorosulfoxidation of alkenes

Batch and Continuous-Flow Electrochemical Geminal Difluorination of Indeno[1,2-c]furans

An electrochemical gem-difluorination of indeno[1,2-c]furans using commercially available and easy-to-use triethylamine trihydrofluoride as both the electrolyte and fluorinating agent was developed. Remarkably, different reaction pathways of indeno[1,2-c]furans, i.e., paired electrolysis and net oxidation, are operative in a batch reactor and a continuous-flow microreactor to afford the corresponding gem-difluorinated indanones and indenones, respectively.

Metal-Free Electrocatalytic Synthesis of Fused Azabicycles from N-Allyl Enamine Carboxylates

An electrocatalytic approach to access structurally significant azabicyclic scaffolds from N-allyl enamine carboxylates is illustrated. This metal-free method functions exclusively with a catalytic amount of iodide, strategically employed to electrochemically generate a reactive hypervalent iodine species, which facilitates the cascade bicyclization processes with enhanced precision and efficiency. Excellent functional group compatibility was observed, enabling the synthesis of a series of azabicycle derivatives. Detailed mechanistic and electrochemical studies enhance the comprehension of the reaction sequence.

1,2-Fluorosulfenylation of unactivated alkenes with thiols and a fluoride source promoted by bromodimethylsulfonium bromide

A practical method that enables the fluorosulfenylation of unactivated alkenes processed directly with thiols and fluoride salts is presented. Good to excellent efficiencies and functional group tolerance are observed for both alkene substrates and thiols. The procedure also allows the use of gaseous ethylene as a two-carbon building block for β-fluoro thioether products.

Electro-oxidative Synthesis of Unsymmetrical Alkyne-1,4-diones via Sequential Ring Formation and Cleavage

Synthesis of unsymmetrical but-2-yne-1,4-diones is reported through oxidative alkyne translocation of readily accessible homopropargylic alcohols. The developed method consists of an unprecedented one-pot sequential electro-oxidative annulation-fragmentation-chemical selenoxide elimination process. Excellent functional group compatibility was observed, and an array of yne-1,4-diones were synthesized. Derivatization of the alkyne gave access to other valuable scaffolds. Detailed mechanistic studies through the isolation of key intermediates clarified the cascade transformation.

Copper(I)-Catalyzed Three-Component Selenosulfonation of Maleimides with Sulfonyl Hydrazides and Diselenides via Radical Relay

By employing Cu(CH₃CN)₄PF₆ as the catalyst and tert-butyl hydroperoxide as the oxidant, we realized a three-component radical selenosulfonation of substituted maleimides, sulfonyl hydrazides, and diphenyl diselenides, providing a series of 3,4-selenosulfonylated succinimides in moderate to good yields. This reaction features broad substrate scopes, high functional-group tolerability, and feasibility of gram-scale synthesis, enabling one-step construction of C-SO₂ and C-Se bonds under mild reaction conditions. Preliminary mechanistic studies support the free-radical-induced pathway.

Electrochemical vicinal oxyazidation of α-arylvinyl acetates

α-Azidoketones are valuable and versatile building blocks in the synthesis of various bioactive small molecules. Herein, we describe an environmentally friendly and efficient electrochemical vicinal oxyazidation protocol of α-arylvinyl acetates to afford diverse α-azidoketones in good yields without the use of a stoichiometric amount of chemical oxidant. A range of functionality is shown to be compatible with this transformation, and further applications are demonstrated.

Electrochemical Sulfoxidation of Thiols and Alkyl Halides

Sulfoxides are actively engaged as versatile synthetic building blocks, chiral ligands, bioactive molecules, and function materials. However, their oxidative syntheses from thioethers are inevitably impeded by overoxidation, excess oxidants, and the tedious preparation of thioethers. To address these shortcomings, we report herein a highly selective electrochemical sulfoxidation reaction featuring the use of simple starting materials, i.e., thiols and alkyl halides, in a single operation.

Electrochemical β-chlorosulfoxidation of alkenes

A green and sustainable electrochemical β-chlorosulfoxidation of alkenes with readily available thiols and hydrochloride as the limiting agents has been developed.