S-,P-stabilized bromoallenes for modular allenylborylation of alkenes

Simultaneously forming a carbon-carbon and a carbon-heteroatom bond in a single step through transition metal-catalyzed alkene difunctionalization strategy has emerged as a powerful tool for synthetic organic chemistry.Due to the uncontrollable reactivity,direct cross-coupling with bromoallenes as the building blocks for the selective allenation and borylation remains challenging.We herein report a new type of S-and P-stabilized bromoallenes for palladium-catalyzed modular allenation and borylation of alkenes to the divergent synthesis of multiply functionalized allenes in a highly regio-and diastereoselective manifold.The reaction features broad substrate scope and wide functional group compatibility,thus providing a straightforward method to install allenyl and boryl groups across alkenes.Control experiments highlight the crucial importance of S-,P-stabilization for the oxidative insertion of Pd-species into the allenyl-Br bond.The facile syntheses of bioactive allenic steroids and exocyclic allenes demonstrate the synthetic utility of this protocol.

Photocatalyzed ditrifluoromethylthiolation of alkenes with CF_(3)SO_(2)Na

Since the first report of sodium trifluoromethanesulfinate(CF_(3)SO_(2)Na) as an electrophilic trifluoromethylthiolation reagent in 2015,there has been no breakthrough in research in this field.Herein,we disclose an unprecedented usage of CF_(3)SO_(2)Na as a radical trifluoromethylthiolation reagent.A photocatalyzed ditrifluoromethylthiolation of alkenes with CF_(3)SO_(2)Na in the presence of PPh_(3) and catalytic copper has been developed.Interestingly,either Ir[(p-Fppy)_(2)(bpy)]PF_6 or Ir(ppy)_(3) could facilitate this transformation.Mechanistic studies indicate that initiation of the radical chain proceeded via two different photocatalytic quenching mechanisms.This protocol provides a practical method for the construction of diverse vicinal ditrifluoromethylthiolated compounds.

Nickel-Catalyzed Stereoselective Migratory Carboboration of 1,4-Cyclohexadiene

Multi-substituted cyclohexanes play a crucial role as scaffolds in bioactive compounds.While significant progress has been made in synthesizing substituted cyclohexanes,methods for the stereoselective assembly of 1,3-disubstituted cyclohexanes remain scarce.This study presents a novel approach involving nickel catalysis to achieve stereoselective carboboration of 1,4-cyclohexadiene.This innovative process allows for the simultaneous introduction of a boron group and an aryl or an alkyl fragment into the 1,4-cyclohexadiene framework under mild conditions,with exclusive regioselectivity and excellent cis configuration.The resulting products feature a double carbon bond and the incorporation of the boron group,offering significant potential for subsequent transformations and downstream applications.

Catalytically generated noncovalent ammonium dienolate:a versatile platform for the development of organocatalytic asymmetric cascade reactions

Organocatalytic cascade reactions represent a powerful strategy for the rapid construction of complex chiral molecules with multiple stereocenters from simple substrates under mild conditions. The intriguing structural feature and diverse reactivity of catalytically generated dienolate species render them competent and versatile intermediates for the development of practical and valuable cascade reactions. Over the past years, a plethora of innovative and pioneering noncovalent ammonium dienolatemediated cascade reactions have been designed and implemented under the catalysis of chiral organocatalysts, making dienolate activation a general, robust, and complementary method for the functionalization of unsaturated carbonyl compounds and related substances. This review illustrates the recent advances in organocatalytic noncovalent ammonium dienolate-mediated cascade reactions(mainly from 2010 to 2023), including the cascade transformations of ammonium dienolates directly generated from unsaturated ketone/aldehyde, ester/lactone/azlactone, amide/lactam/pyrazolone/oxindole, and alkylidene nitrile compounds. The contents are arranged based on the reaction types of the ammonium dienolates, with an emphasis on cascade 2,5-, 3,5-, and 4,5-difunctionalizations of these intermediates. Furthermore, other cascade reactions involving the 1,3-, 2,3-, and even more complex 3,4,5-reactivities of ammonium dienolates were also discussed. The reaction pathway, reaction stereoinduction, and synthetic applications of the ammonium dienolate-mediated cascade reactions were highlighted throughout the article. As a stimulating and ever-growing research area, the organocatalytic noncovalent ammonium dienolate-mediated cascade reactions are expected to continue demonstrating their magic power for constructing chiral targets in the future and further expanding the boundaries of asymmetric catalysis.

Recent Advances in Enantioselective Reactions of Terminal Unactivated Alkenes

α-Olefins as aliphatic terminal alkenes could be obtained easily from numerous contemporary synthetic reactions as well as petro-chemical industry,and also found in natural products.Compared to the alkenes attaching the directing groups or activating group,the catalytic asymmetric reaction of unactivated terminal alkenes presents great challenges due to the weak electron effect and small steric hindrance effect.This review mainly summarizes the latest progress of the asymmetric reaction of unactivated terminal olefins since 2016.

Synergistic Brønsted Base/Photoredox-Catalyzed Three-Component Coupling with Malonates to Synthesize δ-Hydroxy Esters and δ-Keto Esters

Multicomponent alkene 1,2-dicarbofunctionalizations(DCFs)have emerged as a powerful strategy to rapidly incorporate both two carbon subunits across one C-C double bond in one step for enhancing molecular complexity and diversity.To the best of our knowledge,there is only one report on photoredox-catalyzed three-component DCFs with malonates through the radical−radical cross-coupling,while photoredox-catalyzed radical-polar crossover(RPC)-type DCFs with malonates were still rare.Herein,we describe a redox-neutral RPC-type 1,2-dialkylation of styrenes with malonates and aldehydes through the synergistic Brønsted base/photoredox catalysis system.This transition-metal-free strategy provides an efficient and clean approach to a broad variety ofδ-hydroxy esters and also features exceptionally mild conditions,wide compatibility of substrate scope and functional groups,and high atomic economy.Moreover,three-component 1,2-alkylacylation from the same starting materials was achieved in one-pot manner through such RPC-type coupling and subsequent two-electron oxidation process,providing a set ofδ-keto esters of interest in pharmaceutical research.

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 singleelectron-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.

Photoinduced difunctionalization with bifunctional reagents containing N-heteroaryl moieties

Bifunctional reagents that serve as dual coupling partners with an activating species have emerged as valuable synthetic tools in organic chemistry.They allow for the development of diverse reaction modes with enhanced efficiency and structural variability,which is in high demand for atom-economic and sustainable synthesis.Among them,bifunctional reagents containing Nheteroaryl groups have received much attention due to their ability to introduce privileged N-heteroaryl moieties into complex molecules that are otherwise challenging to access.Furthermore,these reagents have been employed under visible-light conditions to achieve various synthetic applications,enabling difunctionalization of alkenes,alkynes,and[1.1.1]propellanes under mild reaction conditions,providing access to highly functionalized N-heteroarenes.In this review,we provide an overview of the recent achievements and applications of photoinduced difunctionalization using bifunctional reagents containing N-heteroaryl groups.We systematically categorize the representative contributions in the field based on bifunctional reagents and their reactivity patterns.This review aims to highlight the potential of these reagents as powerful synthetic tools for sustainable and diverse synthesis.

Electrophotocatalytic Reductive 1,2-Diarylation of Alkenes with Aryl Halides and Cyanoaromatics

Comprehensive Summary The radical-mediated reductive functionalization of aryl halides has been extensively studied.However,the related radical-mediated intermolecular reductive 1,2-diarylation of alkenes,using aryl halides as aryl radical sources,remains unexplored.Herein,a new electrophotocatalytic intermolecular reductive 1,2-diarylation of alkenes is reported using aryl halides and cyanoaromatics to produce polyarylated alkanes.Using synergistic cathodic reduction and visible-light photoredox catalysis,various electron-rich and electron-deficient aryl halides are combined with various alkenes and cyanoaromatics to characterize the broad substrate scope,excellent functional group compatibility,and excellent selectivity of this reaction.Mechanistic investigations reveal that this reaction may proceed via a radical process initiated by the reductive generation of aryl radicals from aryl halides and terminated by radical-radical coupling with cyanoaromatic radical anions.

Cobalt-Catalyzed Difunctionalization of Styrenes via Ligand Relay Catalysis

Here,we report a cobalt-catalyzed sequential dehydrogenative Heck silylation/hydroamination of styrenes with hydrosilane and diazo compound to access 1-amino-2-silyl compounds with excellent regioselectivity.This difunctionalization reaction could undergo smoothly using 1 mol%catalyst loading with good functional group tolerance.Not only di-and tri-substituted hydrosilanes,but also alkoxysilane is suitable,which does explore the scope of the family of 1-amino-2-silyl compounds.The ligand relay phenomenon between neutral tridentate NNN ligand and anionic NNN ligand is observed for the first time via absorption spectral analysis in this one-pot,two-step transformations.The primary mechanism has been proposed based on the control experiments.

Formal Deoxygenative Cross-Coupling of Aldehydes to Ketones throughα-Haloboronates:A Route to Deoxygenative Hydroacylation of Aldehydes

Aldehydes are a kind of important synthons and reagents in organic synthesis.The efforts on transformations of aldehydes are highly rewarding and have always attracted considerable attention.Herein,a cross-coupling of aldehydes withα-haloboronates has been achieved under dual nickel/photoredox catalysis system.Considering theα-haloboronates can be easily obtained from aldehydes with our deoxygenative difunctionalization of carbonyls(DODC)strategy,this protocol provides a formal deoxygenative cross-coupling of aldehydes to one-carbon-prolonged ketone products.The mild conditions enabled good functional group tolerance and broad substrate applicability.The application of this method was presented via a tunable synthesis of two ketones with very similar skeletons from two same aldehydes.

Copper-promoted domino cyanation/Ullmann coupling toward difunctionalized acenaphthylenes with various optoelectronic properties

Tremendous progress has been made on aromatic fusion of acenaphthylene towards organic semiconductors.However,scarce studies focus on the functionalization of acenaphthylene without resort to aromatic extension,although vinylene double bond is highly reactive ascribed to the ring strain of the fused cyclopentene.Herein,for the first time we employ copper-promoted domino cyanation/Ullmann coupling to achieve a series of difunctionalized acenaphthylene imides(ANIs)with varied optoelectronic properties.Both Ullmann homocoupling and crosscoupling can be combined with cyanation for difunctionalization of ANIs.The introduction of cyano groups influences oppositely not only the energy levels but also the antiaromaticity of the fivemembered rings in ANIs relative to the dimethylamino substituent due to the electron donating or withdrawing effects.By altering the functional units,the optical and electrical characteristics have been tailored rationally;thus p,n or ambipolar semiconducting properties can be achieved for the ANI derivatives.This article opens up possibilities to the development of organic semiconducting materials based on ANIs without aromatic extension,which is promising for applications in organic electronics.

Synergistic Pd/Cu-catalyzed regio-and stereoselective cascade Heck cyclization/borylation/cross-coupling

A cooperative Pd/Cu-catalyzed three-component cross-coupling reaction of alkynes,B_(2)Pin_(2) and alkene-tethered aryl halides is reported.This reaction proceeds under mild conditions and shows broad sub-strate scope,providing a variety of heterocycles containing tetrasubstituted alkenylboronate moieties in synthetically useful yields with excellent chemoselectivity and regioselectivity.This transformation fea-tures the catalytic generation ofβ-borylalkenylcopper intermediates and their use in Pd-catalyzed Heck cyclization/cross-couplings.An enantioselective cascade cyclization/cross-coupling process has also been developed for the synthesis of enantiomerically enriched oxindole bearing a tetrasubstituted alkenyl-boronate moiety.

Palladium-Catalyzed One-Step Synthesis of Stereodefined Difunctionalized Glycals

Efficiently modifying glycals by directly introducing functional groups into their double bonds is a longstanding challenge.Here,the strategy of introducing two different functional groups into 1-iodoglycals to obtain modified glycals in one step through palladium catalysis was reported for the first time,and the modified glycals contained stereodefined tetrasubstituted olefins.Using this method,various difunctionalized glycals that were difficult to form by other routes were synthesized in moderate to good yields.Control experiments and density functional theory calculations show that the palladium catalyst played dual roles in this transformation,namely,inducing nucleophilic substitution and catalyzing Suzuki coupling.The reaction intermediate was isolated and confirmed by X-ray crystallographic analysis.Furthermore,the gram-scale synthesis and facile deprotection of the target compound enhances the practicality of this strategy.

Aggregation-enabled alkene insertion into carbon–halogen bonds

Molecular aggregation affects the electronic interactions between molecules and has emerged as a powerful tool in material science.Aggregate effect finds wide applications in the research of new physical phenomena;however,its value for chemical reaction development has been far less explored.Herein,we report the development of aggregation-enabled alkene insertion into carbon–halogen bonds.The spontaneous cleavage of C–X(X=Cl,Br,or I)bonds generates an intimate ion pair,which can be quickly captured by alkenes in an aggregated state.Additional catalysts or promoters are not necessary under such circumstances,and solvent quenching experiments indicate that the aggregated state is critical for achieving such sequences.The ionic insertion mode is supported by mechanistic studies,density functional theory calculations,and symmetry-adapted perturbation theory analysis.Results also show that the non-aggregated state may quench the transition state and terminate the insertion process.

Recent Advances on the Electrochemical Difunctionalization of Alkenes/Alkynes

Electroorganic synthesis is an emerging area of high impact research in organic chemistry, which is considered as one of the green and efficient methods and attracts growing research attention. In this review, we summarized comprehensively the recent literature reports on the electrochemical oxidative difunctionalization of unsaturated C—C bonds. The reaction types described in this review included electrochemical intermolecular cyclization, electrochemical intramolecular cyclization, and electrochemical difunctionalization of alkenes/alkynes. This review focuses on the discussion of its synthetic generality for the preparation of functionalized compounds and the related electrochemical oxidative reaction mechanism.

Metal-free tetra-n-butylammonium bromide-mediated aerobic oxidative synthesis of β-ketosulfones from styrenes

An efficient and broadly applicable protocol for the aerobic coupling of styrenes with sulfonylhydrazides has been developed that affords P-ketosulfones bearing various functional groups in moderate to excellent yields.The preliminary experimental results support the involvement of active benzyl radical species,and a radical pathway was therefore proposed for the reaction.

Modular Synthesis of Diarylalkanes by Nickel-Catalyzed 1,1-Diarylation of Unactivated Terminal Alkenes

A nickel-catalyzed 1,1-diarylation of electronically unbiased alkenes has been developed,providing straightforward access to diarylalkanes from readily available materials.Importantly,both the efficiency and the regioselectivity of this transformation are ensured by reaction conditions,rather than the coordinating group of substrates.We also demonstrate that under balloon pressure,ethylene and propylene can also be utilized as substrates.Preliminary mechanistic experiments suggest that this transformation involves a Ni(0)/Ni(Ⅱ)catalytic cycle rather than a Ni(Ⅰ)/Ni(Ⅲ)cycle.

Radical azidation as a means of constructing C(sp^(3) )-N_(3) bonds

The azido group is found in large numbers of natural products,drugs,biochemicals and materials and to date,many elegant and useful methods for the synthesis of organic azides and their transformations have been documented.In this review,we provide a summary of the state of the art of radical azidation for the construction of C(sp^(3) )-N_(3) bonds.There is a specific emphasis on the synthetic reactions involving C(sp^(3))-H azidation,decar-boxylative azidation and difunctionalized azidation of olefins.This review will be useful to those working in this field and hopefully could inspire further development of radical azidation reactions.

Copper-catalyzed 1,1-difunctionalization of terminal alkynes: a three-component reaction for the construction of vinyl sulfones

A copper-catalyzed 1,1-difunctionalization of terminal alkynes was achieved via a three-component reaction, providing a variety of vinyl sulfones with good yields and excellent chemo-and stereoselectivity. Preliminary mechanistic studies indicated that the reaction probably underwent a Cu-catalyzed formal C–H insertion to produce an allene intermediate, which was then trapped by a sulfonyl anion to give the corresponding product.