Nickel catalyzed multicomponent stereodivergent synthesis of olefins enabled by electrochemistry, photocatalysis and photo-electrochemistry

Abstract

Trisubstituted alkenes are important organic synthons and have broad applications in the synthesis of many pharmaceuticals and materials. The stereoselective synthesis of such compounds has long been a research focus for organic researchers. Herein, we report a three-component, reductive cascade, cross-coupling reaction for the arylalkylation of alkynes. A wide range of trisubstituted alkenes are obtained in good to high yields with excellent chemo- and stereoselectivity by switching between electrochemistry and photocatalysis. The E isomer of the product is obtained exclusively when the reaction is conducted with electricity and nickel, while the Z isomer is generated with high stereoselectivity when photo- and nickel dual catalysts are used. Moreover, photo-assisted electrochemically enabled nickel catalyzed protocol is demonstrated to selectively deliver Z-trisubstituted alkenes without the addition of photocatalysts.

Facile and General Electrochemical Diselenylation of Terminal Alkynes

“…13−15 More recently, radicalmediated reactions have been devised, which provide an effective technique for difunctionalizing terminal alkynes. 16−18 In general, a radical is generated from various radical precursors, such as sulfonyl chlorides, α,β-unsaturated ketones, activated alkyl bromides, fluoroalkyl iodides, etc., 16−22 which is via a single electron transfer (SET) process employing transition metal species, 23−25 photocatalysts, 26−29 or electrocatalysis 30 (Scheme 1b). These processes are usually transition metal-catalyzed multicomponent reactions, and heavy metal residues are long-standing issues.…”

Zinc-free, Scalable Reductive Cross-Electrophile Coupling Driven by Electrochemistry in an Undivided Cell

“…Li recently reported on a paired-electrolysis approach in NMP where the anodic oxidation of triphenylphosphine generates phosphonium bromide in situ which converts alcohols to alkyl bromides, the substrate for the cathodic cross-electrophile coupling reaction . Rueping demonstrated the arylalkylation of alkynes using electrochemistry and photoassisted electrochemistry to selectively form the E and Z isomers, respectively, using a terminal amine reductant in DMA . These approaches use an undivided cell but again rely on an amide solvent and high equivalents of coupling partners.…”

Ligand-controlled stereodivergent alkenylation of alkynes to access functionalized trans- and cis-1,3-dienes

“…Recently, radical-involved catalytic 1,2-difunctionalization of alkynes has been disclosed to furnish trisubstituted alkenes with complementary anti-selectivity [35][36][37][38][39][40][41][42] . Particularly, utilizing dual nickel/ photoredox catalysis [43][44][45][46][47] has further exploited a number of selective difunctionalization of alkynes with diverse coupling partners under mild conditions [48][49][50][51][52][53][54][55][56] . Nevertheless, rare examples for stereodivergent synthesis of both transand cis-substituted alkenes from alkynes are reported.…”