Anti-Markovnikov ring-opening of sulfonium salts with alkynes by visible light/copper catalysis

Internal alkynes are widespread skeletons in bioactive molecules and materials which are also used as important building blocks in chemical synthesis. Herein, we report a novel and efficient copper-catalyzed Sonogashira reaction between sulfonium salts and alkynes through an anti-Markovnikov ring-opening pathway promoted by visible light. The coexistence of the nitrogen and phosphorus ligands in the system is the key to the success of this reaction. This radical type ring-opening reaction affords a new strategy for the synthesis of internal alkynes. Furthermore, this study is also an effective complement to the diverse reaction patterns of sulfonium salts.

β-C(sp^(3))−H chlorination of amide derivatives via photoinduced copper charge transfer catalysis

An atom economicβ-C(sp^(3))−H chlorination of amide derivatives has been developed.This mild protocol employs CuCl_(2) instead of palladium catalysts with atom-economic HCl as chlorine sources and enables the late-stage functionalization of medicine derivatives.Mechanism studies suggest a plausible visible light triggered ligand-to-metal charge transfer(LMCT)/1,4-hydrogen atom transfer(HAT)cascade.

Copper-catalyzed C(sp)-H aryl amination enables modular synthesis of quinolines and 2-quinolinones

Herein,we disclose a novel copper-catalyzed C(sp)-H aryl amination of terminal alkynes with anthranils,enabling the rapid generation of highly reactive secondary N-aryl ynamines for the modular synthesis of structurally diverse C2-substituted quinolines and 2-quinolinones.The in-situ formed carbonyl-ynamines are prone to tautomerize to carbonyl-ketenimines,which can efficiently react with a series of nucleophiles,including amines,alcohols,phenols,thiols,thiophenols,active-methylene compounds,and even water to produce various quinoline derivatives with the generation of H_(2)O as a sole and green byproduct.This method also unlocks a practical route to create various quinoline-fused heterocycles and can be successfully applied to the late-stage modification of complex molecules and the concise synthesis of bioactive targets.Mechanistic studies reveal a coppercatalyzed inner-sphere nitrene transfer process by using anthranils as novel aryl nitrene precursors.

Photoinduced copper-catalyzed alkoxyl radical-triggered ring-expansion/aminocarbonylation cascade

A photoinduced copper-catalyzed alkoxyl triggered C-C bond cleavage/aminocarbonylation cascade is presented.Through adjusting the structure of alkoxyl radical precursors,functionalized lactones and ketoamides were synthesized with good yields and excellent functional group tolerance under redox-neutral conditions.Notably,this protocol enables the integration of lactone fragments with many amine drugs and drug fragments.

Copper-Catalyzed Ligand-Controlled Selective Borocarbonylation of α-Substituted Styrenes Toward β-Boryl Aldehydes and Cyclopropyl Boronate Esters

We report a copper-catalyzed ligand-controlled selective carbonylative borofunctionalization ofα-substituted styrenes.This reaction provides a general and versatile procedure to synthesize a variety of synthetically usefulβ-boryl quaternary aldehydes and cyclopropyl boronate esters bearing a quaternary carbon center.With NHC(IMes=1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene)as the ligand,the carbene intermediate reacts with O-H bond of alcohol while the carbene intermediate would undergo C-H bond insertion when using phosphine ligand[1,2-bis(diphenylphospino)ethane]as the ligand.Formation of a carbene intermediate has been proposed as the key step for this transformation.

Recent Developments in Copper(Ⅰ)-Catalyzed Enantioselective Alkynylation Reactions via a Radical Process

Alkynes are one of the most significant functional groups in organic chemistry and great efforts have been made to explore efficient approach for the construction of chiral alkynes.The asymmetric C(sp^(3))–C(sp)cross-coupling provides a significant complementary strategy through radical-initiated process.However,the stereocontrol of highly reactive and unstable radical intermediate has been a challenge for decades.To address this problem,a variety of chiral ligands are developed for initiating the reaction and achieving enantiocontrol of alkyl radicals.This review summarizes recent developments in copper-catalyzed enantioselective alkynylation of prochiral alkyl radicals and their brief mechanistic studies.

CVD growth of graphene on copper-plated scrap steel without external carbon source

Chemical vapor deposition(CVD)using gaseous hydrocarbon sources has shown great promise for large-scale graphene growth,but high growth temperatures(typically 1000℃)require sophisticated and expensive equipment,which increases graphene production costs.Here,we demonstrate a new approach to produce graphene at low cost from scrap steel sheets treated by thermal evaporation of copper plating,which is a derivative of traditional CVD technology.Without additional carbon sources,graphene film was successfully prepared on copper-coated scrap steel sheets at 820℃.The resulting graphene has few defects and uniform morphology,comparable to CVD graphene grown at 1000℃.Finally,the obtained graphene film is used in combination with an interdigital electrode to detect NO_(2)successfully,showing excellent performance.This technology expands the application of graphene in the manufacture of gas sensing devices and is compatible with traditional microelectronics technology.

Cu-catalyzed regioselective diborylation of 1,3-enynes for the efficient synthesis of 1,4-diborylated allenes

Borylation of 1,3-enynes with bis(boronate)compounds often ends up with the formation of hydroborylated products,leaving the diborylation of 1,3-enynes for the formation of 1,4-diborylated allenes to be challenging.Herein,a copper-catalyzed chemo-,regio-,and stereo-selective diborylation of 1,3-enynes for the efficient construction of 1,4-diborylated allenes under base-free conditions was reported.A wide range of 1,3-enynes bearing various functional groups can participant in the reaction and afforded the corresponding 1,4-diborylated allenes in good to excellent yields,which was enabled by the protocol of Bpin to BF3K conversion.the borylcopper species was supposed to selectively attack the C-C triple bond of the 1,3-enynes.

SO_(2)-Insertion induced enantioselective oxysulfonylation to access β-chiral sulfones with quaternary carbon stereocenters

β-Chiral sulfones are structural motifs widely found in natural products and bioactive molecules, while also serving as important intermediates for the synthesis of valuable chiral scaffolds. In contrast to the rapid growth of sulfur dioxide insertion chemistry over the last decade, enantioselective catalytic variants for accessing β-chiral sulfones, especially those bearing a quaternary carbon stereocenter, remain rare. Herein, we report an enantioselective copper/bisoxazoline catalyzed oxysulfonylation of alkenes to yield isoxazolinyl-containing β-chiral sulfones bearing quaternary carbon stereocenters with moderate to excellent yields and up to 96:4 er. The advantage and irreplaceability of this sulfur dioxide insertion catalytic system have been demonstrated by achieving transformations clearly unavailable with the previously reported sulfonyl chloride system. Additionally,the recoverability of the new-developed bisoxazoline ligand L9 and its reusability without any erosion of the catalytic activity and enantioselectivity further demonstrate the usefulness of the protocol.

Enantioselective Arylcyanation of Styrenes via Copper-Catalyzed Radical Relay

The first copper-catalyzed enantioselective arylcyanation of styrenes has been developed using readily available anilines as aryl radical precursors under mild conditions,which enables easy access to chiral 2,3-diaryl propionitriles with moderate to good enantiose-lectivities.This operationally straightforward reaction exhibits broad substrate scope and functional group tolerance.Notably,this method has been applied to the synthesis of chiral AlEgen as well as estrogen receptor-B agonist(R)-diarylpropionitrile(DPN).

Copper-Catalyzed Hydrosulfonylation of Alkynes Employing Sulfonohydrazides toward the Synthesis of Vinyl Sulfones

The hydrosulfonylation of terminal alkynes employing sulfonohydrazides has been accomplished with cop- per-catalysis in the presence of BPO （benzoic peroxyanhydride）. Generally, excellent yield of the vinyl sulfone products has been acquired by heating the reaction at 70℃ in DMSO.

Copper-Catalyzed Aerobic Oxidative Ring Expansion of Isatins: A Facile Entry to Isoquinolino-Fused Quinazolinones

A copper-catalyzed aerobic oxidative ring expansion reaction of isatins with 1,2,3,4-tetrahydroisoquinoline for the synthesis of tetra-cyclic quinazolinones has been developed.This reaction is performed smoothly under simple conditions to give the corresponding products in moderate to good yields with good functional group tolerance.

Recent progress in copper catalyzed asymmetric Henry reaction

Henry reaction is one of the most classical reactions to construct synthetically useful product nitro alcohol, which as a privileged skeleton is widely distributed in various pharmaceuticals. This review summarizes the recent progress of copper-catalyzed asymmetric Henry reaction from 2011 to 2016. The significant progress that has been made in this area will be highlighted and some of challenges that the author believes may be hindering further progress will be revealed.

Copper-Catalyzed Asymmetric Hydroamination:A Unified Strategy for the Synthesis of Chiralβ-Amino Acid and Its Derivatives

Catalytic asymmetric aza-Michael represents one of the most convenient and atom-economical approaches for the rapid construction of biologically active chiralβ-amino acid frameworks.However,the direct enantioselective addition of nitrogen-based nucleophiles to intrinsically low reactivity ofα,β-unsaturated carboxylic acid,ester,and amide,as well as simpleα,β-unsaturated nitrile,remains a long-standing challenge.

Copper catalyzed borylative cyclization of 3-arylallyl carbamoyl chloride with B_(2)pin_(2):stereoselective synthesis of cis-2-aryl-3-boryl-γ-lactams

Borylative cyclization of E-3-arylallyl carbamoyl chlorides is achieved through copper catalyzed intramolecular carboboration with B_(2)pin_(2).2-Aryl-3-boryl-γ-lactams are formed with exclusive cisdiastereoselectivity.CuBr-Dppp combination gives the best outcomes.The substrate scope is profiled.

Copper-catalyzed decarboxylative Se insertion coupling of indoles and propiolic acids

A novel and efficient copper-catalyzed decarboxylative alkynylselenation of indoles with Se powder and propiolic acids has been developed.The outstanding advantages of this protocol not only nicely avoid the use of prefabricated arylselenation reagent and address the facile over-selention issues,but also enrich the chemistry of selenium powder.Importantly,this reaction could be extended to pyrrole,and the practical utility of this transformation has been demonstrated in gram-scale synthesis and late-stage indolylselenation of Clofibrate-derived propiolic acid.

Copper-catalyzed asymmetric propargylic substitution of anthrones and propargylic esters

Anthrones are key structural motifs in many natural products, bioactive compounds and pharmaceutical chemicals. Earth-abundant-metal-catalyzed asymmetric functionalization of anthrones has not proved to be viable. Herein, we disclosed a highly enantioselective propargylic substitution of anthrones with propargylic esters using copper salts with chiral N, N, P-ligand. This strategy is amenable to a broad range of substrates, uses readily available starting materials, provides excellent yields with remarkable enantioselectivity under mild conditions, and enables attractive products diversification routes.

Copper-catalyzed diversified annulations betweenα-diketones and alkynylα-diketones

Copper-catalyzed divergent annulations betweenα-diketones and alkynylα-diketones have been achieved,delivering a series of highly functionalized and biologically important cis-hexahydro-2Hcyclopenta[b]furan(HCPF)and 2-hydroxydihydrofuran-3(2H)-one(HDFO)products with high levels of stereoselectivity under identical conditions.The protocol features the use of earth-abundant copper catalyst,mild conditions,shortening synthetic routes in constructing different molecular frameworks,and reducing the corresponding possible waste production.The substituents of the nucleophilicα-diketones play crucial roles in switching the reaction pathways.

Access to Stereodefined Multifunctionalizedβ,γ-Unsaturated Ketones via Chemo,Regio-and Diastereoselective Copper-Catalyzed Diborylation of Cross-Conjugated Enynones

Main observation and conclusion Stereodefinedβ,γ-unsaturated carbony|compounds are important yet synthetically challenging units in natural products and drugs.Disclosed herein is a mild,rapid copper-catalyzed diborylation reaction of cross-conjugated enynones as a step-economic and modular approach to stereodefined multifunctionalizedβ,γ-unsaturated ketones by fine control of chemo-,regio-,Z/E and diastereoselectivity.The substrate scope was examined and a possible catalytic cycle was proposed to explain the multifaceted selectivity.

Copper-Catalyzed Ring-Opening/Borylation of Cyclopropenes

Since organoboron compounds readily undergo a diverse array of transformations and are widely used in various fields,the development of C-B-bondforming reactions have attracted considerable attention.Herein,we report a new method for forming C-B bonds by means of Cu-catalyzed ring-opening/borylation reactions of cyclopropenes.This method provides efficient access to a new type of stable allylborane-Lewis base adduct,which is a versatile synthon.The configuration of the products can be well controlled with this method,and some of the configurations we obtained are inaccessible by other catalytic methods for generating allylborons.Mechanistic studies indicated that the reactions proceed via insertion of an alkenyl Cu carbene—generated in situ by cyclopropene ring opening—into the B-H bond;the ring-opening step determines both the rate and stereochemistry.