Electrochemical Difunctionalization of Terminal Alkynes: Access to 1,4-Dicarbonyl Compounds

Enantioselective Palladium-Catalyzed Domino Carbonylative Heck Esterification of o-Iodoalkenylbenzenes with Arylboronic Acids

The current investigation presents an innovative palladium-catalyzed asymmetric carbonylative Heck esterification method. This approach facilitates the efficient synthesis of various chiral γ-ketoacid esters by utilizing o-alkenyliodobenzenes and arylboronic acids as primary substrates. This reaction achieves the creation of three carbon-carbon bonds, two carbon-oxygen bonds, and the establishment of a quaternary carbon center within a single step. The α-chiral γ-ketoacid esters were obtained in yields ranging from good to high yields, displaying enantiomeric excesses (ee's) levels up to 92% under mild reaction conditions.

Tuning Benzylic C-H Functionalization of (Thio)xanthenes with Electrochemistry

Here, we report a tunable electrochemical benzylic C-H functionalization of (thio)xanthenes with terminal alkynes and nitriles in the absence of any catalyst or external chemical oxidant. The benzylic C-H functionalization can be well controlled by varying the electrochemical conditions, affording the specific coupling products via C-C and C-N bond formation.

Electrochemical Annulation of Indole-Tethered Alkynes Enabling Synthesis of Exocyclic Alkenyl Tetrahydrocarbazoles

An electrochemical sulfonylation-triggered cyclization reaction of indole-tethered terminal alkynes with sulfinates as sulfonyl sources has been developed, which affords exocyclic alkenyl tetrahydrocarbazoles in good chemical yields. This reaction features convenient operation and tolerates a wide scope of substrates with a variety of electronically and sterically diverse substituents. Furthermore, high E-stereoselectivity is observed for this reaction, which provides an efficient method for the preparation of functionalized tetrahydrocarbazole derivatives.

Electrochemical monofluoroalkylation cyclization of N-arylacrylamides to construct monofluorinated 2-oxindoles

An electrochemical monofluoroalkylation cyclization of N-arylacrylamides to synthesize monofluorinated 2-oxindoles has been developed, which employs common dimethyl 2-fluoromalonate as a monofluoroalkyl radical precursor and obviates the use of prefunctionalized monofluoroalkylation reagents and sacrificial oxidants. A variety of monofluorinated nitrogen-containing heterocyclic compounds were efficiently obtained with satisfactory yields from readily available materials.

Recent advances in electrooxidative radical transformations of alkynes

During the past few years, electrochemical oxidative reactions through radical intermediates have emerged as an environmentally-benign, powerful platform for the facile formation of C–E (E = C, N, S, Se, O and Hal) bonds through single-electron-transfer (SET) processes at the electrodes. Functionalized unsaturated molecules and unusual structural motifs can, for instance, be directly constructed under exceedingly mild reaction conditions through initial radical attack onto alkynes. This minireview highlights the recent advances in electrooxidation in radical reactions until June 2022, with a particular focus on radical additions onto alkynes.

imethyl 2-Benzylmalonate

An electrochemical dearomatizing spirocyclization of alkynes with dimethyl 2-benzylmalonates for the preparation of spiro[4.5]deca-trienones has been developed. This approach adopts ferrocene (Cp₂Fe) as an electrocatalyst to produce carbon-centered radical intermediates from C-H-based malonates, which obviates the forthputting of noble-metal reagents, sacrificial chemical oxidants and 2-bromomalonates. A wide variety of spiro compounds are efficiently prepared with satisfactory results under mild conditions.

Regio- and stereoselective electrochemical selenoalkylation of alkynes with 1,3-dicarbonyl compounds and diselenides

A regio- and stereoselective electrochemical approach for the selenoalkylation of alkynes with 1,3-dicarbonyl compounds and diselenides has been developed.