Ligand-Controlled Regiodivergent and Enantioselective Copper-Catalyzed Hydroallylation of Alkynes

Regioselective Nickel-Catalyzed Hydrotrifluoroalkylation of Alkynes to Construct Trisubstituted Allylic Trifluoromethyl Alkenes

Introducing fluorine atoms or fluorine-containing groups into drug molecules has become a common approach in drug design, with the incorporation of trifluoromethyl groups as a focal point of research in the field of organic fluorochemistry. Here, we describe a nickel-catalyzed hydrotrifluoromethylation of internal alkynes with trifluoromethyl alkyl bromides to synthesize a series of highly regioselective trifluoromethyl allyl trisubstituted alkenes. This reaction is characterized by mild conditions and broad functional-group tolerance, providing an efficient and practical approach to synthesize trifluoromethyl allyl trisubstituted alkenes.

Meyer-Schuster rearrangement/allylic alkenylation of propynolaldehydes with olefins to synthesize skipped 1,4-dienes

A highly efficient method for the straightforward synthesis of skipped 1,4-dienes is presented via p-TsOH·H2O-catalyzed intramolecular intercepted Meyer-Schuster rearrangement/allylic alkenylation of propynolaldehydes with olefins in a one-pot manner. This cascade transformation is characterized by metal-free and mild conditions, extensive substrate applicability, atom economy, gram-scale production, and water as the sole by-product. Furthermore, the resulting functionalized 1,4-dienes could be derivatized by Fe(III)-promoted radical cyclization, allylic methoxylation under reductive conditions, and Pd(II)-catalyzed Sonogashira coupling.

Enantioselective Multicomponent Electrochemical Difunctionalization of Terminal Alkynes

The direct functionalization of alkyne triple bonds using a radical strategy provides an efficient platform for creating a wide range of substituted alkenes. However, developing a multicomponent enantioselective radical reaction using feedstock alkynes to forge all-carbon quaternary stereocenters─while addressing challenges related to compatibility, selectivity, and efficiency─remains relatively rare. Here we report an enantioselective electrochemical nickel-catalyzed three-component cross-coupling of readily available terminal alkynes, diverse racemic alkyl radical precursors, and group transfer reagents (such as (TMS)3Si-H, RSe-SeR, RTe-TeR, and CHI3), achieving excellent regio-, stereo-, and enantioselectivities (more than 70 examples, up to 95% ee). Electricity-mediated difunctionalizations significantly expand the scope of both aliphatic and aromatic alkynes, demonstrating excellent functional group compatibility. The key to success lies in the rational design of anodically generated nickel-bound tertiary radical intermediates, which stereoselectively capture alkynes to form vinyl radicals and participate in subsequently diverse group transfer processes to enable the intermolecular and anti-stereoselective difunctionalization of alkynes. This approach allows the transformation of terminal alkynes into diverse structural entities with α-quaternary stereogenic centers.

One-Pot Cobalt- or Copper-Catalyzed Asymmetric Ring-Opening Hydrosilylation/Hydroboration of Arylidenecyclopropanes

An operationally convenient cobalt-catalyzed one-pot one-step hydrosilylation/hydroboration reaction of arylidenecyclopropanes is developed to access racemic 1,4-borylsilylalkanes. In addition, the corresponding asymmetric reaction is developed with a chiral copper catalyst to prepare 1,4-borylsilylalkanes with high enantioselectivity by a one-pot two-step procedure. Mechanistic studies reveal that this difunctionalization process begins with metal-hydride-catalyzed ring-opening hydrosilylation of arylidenecyclopropanes to generate homoallylsilane intermediates, followed by regio- or enantioselective metal-hydride-catalyzed hydroboration of homoallylsilanes to produce skipped borylsilylalkanes. Selective transformations of C-B and Si-H bonds in skipped borylsilylalkane products are also demonstrated.

Reductive coupling of allenyl/allyl carbonate with alkyne under dual cobalt-photoredox catalysis

Skipped dienes are among the most prevalent motifs in a vast array of natural products, medicinal compounds, and fatty acids. Herein, we disclose a straightforward one-step reductive protocol under Co/PC for the synthesis of diverse 1,4-dienes with excellent regio- and stereoselectivity. The protocol employs allenyl or allyl carbonate as π-allyl source, allowing for the direct synthesis of skipped diene with a broad range of alkynes including terminal alkynes, propargylic alcohols, and internal alkynes. The method also demonstrated the biomimetic homologation of natural terpenols into synthetic counterparts via iterative allylation of three-carbon allyl units, employing propargylic alcohol as a readily available alkyne source. Experimental studies, control experiments, and DFT calculations suggest the dual catalytic process generates 1,3-diene from allenyl carbonate, followed by proton and electron transfer leading to Co(II)-π-allyl species prior to the alkyne coupling. The catalytic cycle transitions through Co(II), Co(I), and Co(III).

Copper-Catalyzed Regiodivergent Asymmetric Difunctionalization of Terminal Alkynes

We herein describe the first example of ligand-controlled, copper-catalyzed regiodivergent asymmetric difunctionalization of terminal alkynes through a cascade hydroboration and hydroallylation process. The catalytic system, consisting of (R)-DTBM-Segphos and CuBr, could efficiently achieve asymmetric 1,1-difunctionalization of aryl terminal alkynes, while ligand switching to (S,S)-Ph-BPE could result in asymmetric 1,2-difunctionalization exclusively. In addition, alkyl substituted terminal alkynes, especially industrially relevant acetylene and propyne, were also valid feedstocks for asymmetric 1,1-difunctionalization. This protocol is characterized by good functional group tolerance, a broad scope of substrates (>150 examples), and mild reaction conditions. We also showcase the value of this method in the late-stage functionalization of complicated bioactive molecules and simplifying the synthetic routes toward the key intermediacy of natural product (bruguierol A). Mechanistic studies combined with DFT calculations provide insight into the mechanism and origins of this ligand-controlled regio- and stereoselectivity.

Enantioselective Copper-Catalyzed Sequential Hydrosilylation of Arylmethylenecyclopropanes

Despite impressive advances in the construction of enantioenriched silacarbocycles featuring silicon-stereogenic centers via a selection of well-defined sila-synthons, the development of a more convenient and economic method with readily available starting materials is significantly less explored and remains a considerable challenge. Herein, we report the first example of copper-catalyzed sequential hydrosilylation of readily accessible methylenecyclopropanes (MCPs) and primary silanes, affording an efficient and convenient route to a wide range of chiral silacyclopentanes bearing consecutive silicon- and carbon-stereogenic centers with excellent enantio- and diastereoselectivities (generally ≥98 % ee, >25 : 1 dr). Mechanistic studies reveal that these reactions combine copper-catalyzed intermolecular ring-opening hydrosilylation of aryl MCPs and intramolecular asymmetric hydrosilylation of the resultant Z/E mixture of homoallylic silanes.

Regio- and enantioselective nickel-alkyl catalyzed hydroalkylation of alkynes

The migratory insertion of metal-hydride into alkene has allowed regioselective access to organometallics, readily participating in subsequent functionalization as one conventional pathway of hydroalkylation, whereas analogous process with feedstock alkyne is drastically less explored. Among few examples, the regioselectivity of metal-hydride insertion is mostly governed by electronic bias of alkynes. To alter the regioselectivity and drastically expand the intermediate pools that we can access, one aspirational design is through alternative nickel-alkyl insertion, providing opposite regioselectivity induced by steric demand. Leveraging in situ formed nickel-alkyl species, we herein report the regio- and enantioselective hydroalkylation of alkynes with broad functional group tolerance, excellent regio- and enantioselectivity, enabling efficient route to diverse valuable chiral allylic amines motifs. Preliminary mechanistic studies indicate the aminoalkyl radical species can participate in metal-capture and lead to formation of nickel-alkyl, of which the migratory insertion is key to reverse regioselectivity observed in metal-hydride insertion.

Copper-catalyzed asymmetric allylic substitution of racemic/meso substrates

The synthesis of enantiomerically pure compounds is a pivotal subject in the field of chemistry, with enantioselective catalysis currently standing as the primary approach for delivering specific enantiomers. Among these strategies, Cu-catalyzed asymmetric allylic substitution (AAS) is significant and irreplaceable, especially when it comes to the use of non-stabilized nucleophiles (pK a > 25). Although Cu-catalyzed AAS of prochiral substrates has also been widely developed, methodologies involving racemic/meso substrates are highly desirable, as the substrates undergo dynamic processes to give single enantiomer products. Inspired by the pioneering work of the Alexakis, Feringa and Gennari groups, Cu-catalyzed AAS has been continuously employed in deracemization and desymmetrization processes for the synthesis of enantiomerically enriched products. In this review, we mainly focus on the developments of Cu-catalyzed AAS with racemic/meso substrates over the past two decades, providing an explicit outline of the ligands employed, the scope of nucleophiles, the underlying dynamic processes and their practical applications.

Theoretical study of copper hydride complexes catalyzing terminal alkyne hydroalkylation for C(sp2)-C(sp3) bond formation

This study applies Density Functional Theory (DFT) to theoretically investigate the reaction mechanism of a copper complex catalyst facilitating the reaction between a terminal alkyne and α-bromo amide, enabling the formation of E-alkenes through C(sp2)-C(sp3) coupling. Initially, the study explores the reaction mechanism, identifying the predominant reaction pathway and the rate-determining step. Next, we discuss the addition reaction mode of copper hydride with terminal alkynes, determining the causes of regional and stereoselectivity. Subsequently, the reaction mechanism between the alkenyl copper intermediate and α-bromo amide is examined, including the discussion of alkyl fragment activation and introduction methods. Furthermore, the role of NHC ligands in catalyzing the single electron transfer process for C-Br bond activation is investigated. Finally, we analyze and discuss the reasons for the high energy barrier of the non-radical pathway. These investigations not only deepen our understanding of the reaction mechanisms of terminal alkynes and α-bromo amide catalyzed by copper but also provide valuable guidance for the future design of more efficient catalysts and reaction conditions.

Nickel-Catalyzed Ligand-Controlled Regioselective Allylic Alkenylation of Allylic Alcohols with Easily Accessible Alkenyl Boronates: Synthesis of 1,4-Dienes

A nickel-catalyzed direct reaction of allylic alcohols with easily accessible alkenyl boronates has been developed, which provides valuable 1,4-dienes with high regio- and stereoselectivity in good to excellent yields, wide substrate scope, and functional group compatibility. The catalytic system simply consists of Ni(cod)2 as the catalyst and a ligand, without a need for a base and alcohol activator in most cases. The proper choice of ancillary ligands is highly important for this reaction. Depending on the substitution pattern of allylic alcohols and/or alkenyl boronates, different ligands were used for improving the reaction efficiency.

Divergent 1,2-carboallylation of terminal alkynes enabled by metallaphotoredox catalysis with switchable triplet energy transfer

We report a metallaphotoredox strategy for stereodivergent three-component carboallylation of terminal alkynes with allylic carbonates and alkyl trifluoroborates. This redox-neutral dual catalytic protocol utilizes commercially available organic photocatalyst 4CzIPN and nickel catalysts to trigger a radical addition/alkenyl-allyl coupling sequence, enabling straightforward access to functionalized 1,4-dienes in a highly chemo-, regio-selective, and stereodivergent fashion. This reaction features a broad substrate generality and a tunable triplet energy transfer control with pyrene as a simple triplet energy modulator, offering a facile synthesis of complex trans- and cis-selective skipped dienes with the same set of readily available substrates.

Copper-Catalyzed Enantioselective Borylative Allyl-Allyl Coupling of Allenes and Allylic gem-Dichlorides

A catalytic asymmetric reaction between allenes, bis(pinacolato)diboron, and allylic gem-dichlorides is reported. The method involves the coupling of a catalytically generated allyl copper species with the allylic gem-dichloride and provides chiral internal 1,5-dienes featuring (Z)-configured alkenyl boronate and alkenyl chloride units with high levels of chemo-, regio-, enantio-, and diastereoselectivity. The synthetic utility of the products is demonstrated with the synthesis of a range of optically active compounds. DFT calculations reveal key noncovalent substrate-ligand interactions that account for the enantioselectivity outcome and the diastereoselective formation of the (Z)-alkenyl chloride.

Mechanistic Investigation into the Regio-Controllable Hydroallylations of Alkynes with Allylborons under Pd-Based Synergetic Catalyses

Density functional theory calculations were employed to investigate the Pd-catalyzed regio-selective hydroallylations of alkynes with allylborons: cooperation of Cu(OAc)₂ and dppe resulting in 1,4-dienes while combination of AdCO₂H and PCy₃ leading to 1,5-dienes. A unified rationalization mechanism called "Lewis-acid-base-interaction promoted deprotonation/3,3-rearrangement" was proposed. Compared with the commonly reported metathesis pathway to only afford the metal-allyl intermediate, in the newly established mechanism, an additional Brønsted acid (as an initiator of the Pd⁰ oxidative addition) is generated by the interaction of the allylboron (Lewis acid) B atom with the ⁿBuOH (Lewis base) O atom, and subsequent 3,3-rearrangement ensures the thermodynamic feasibility of the reaction. In addition, it was found that excess Cu(OAc)₂ plays two potential roles in the oxidative addition/alkyne insertion: (i) the participation of one AcO^- of Cu(OAc)₂ ensures a large orbital overlap between the migrating H and Pd atoms, facilitating the formal AcO-H cleavage and (ii) the extra (OAc)₂Cu···O(carboxyl) σ-coordination indirectly contributes to the (Me)C≡C(Ph) insertion into the Pd-H bond. Further analysis showed that the origin of the regioselectivity is closely related to the employed phosphorus ligand. These revealed results, which have been overlooked in the previous documents, would aid the development of new related catalytic reactions.

Nickel-Catalyzed Unsymmetrical Bis-Allylation of Alkynes

The catalytic bis-allylation of alkynes is an important but challenging protocol to construct all-carbon tetra-substituted alkenes. Particularly, the catalytic unsymmetrical bis-allylation of alkynes remains as an underexplored task to date. We herein report an unprecedented unsymmetrical bis-allylation by simultaneously utilizing electrophilic trifluoromethyl alkene and nucleophilic allylboronate as the allylic reagents. With the aid of robust Ni⁰ /NHC catalysis, valuable skipped trienes can be obtained in high regio- and stereo-selectivities under mild conditions. Mechanistic studies indicate that the reaction may proceed through a β-fluorine elimination of a nickelacycle followed by a transmetalation step with allylboronate. The present method exhibits a good tolerance of various functional groups. Besides, the skipped triene products can undergo an array of elaborate transformations, which highlights the potential applications of this strategy.

CO2-Promoted and Nickel-Catalyzed Direct Hydroallylation of Terminal Alkynes with Allylic Alcohols: Access to 1,4-Dienes

CO₂-promoted and Ni-catalyzed direct hydroallylation of terminal alkynes with allylic alcohols has been achieved. Various 1,4-dienes could be synthesized in good yield with excellent Markovnikov selectivity for alkyl- and aryl-substituted terminal alkynes under mild reaction conditions. A gram-scale reaction gives considerable yield. Preliminary mechanistic studies support the reaction pathway through sequential carboxylation/allylnickelation/lithium bicarbonate nickelation/transmetalation in the hydroallylation of alkynes with allylic alcohols in the presence of CO₂.

Cobalt-catalyzed branched selective hydroallylation of terminal alkynes

Here, we reported a cobalt-hydride-catalyzed Markovnikov-type hydroallylation of terminal alkynes with allylic electrophile to access valuable and branched skipped dienes (1,4-dienes) with good regioselectivity. This operationally simple protocol exhibits excellent functional group tolerance and exceptional substrate scope. The reactions could be carried out in gram-scale with TON (turn over number) up to 1160, and the products could be easily derivatized. The preliminary mechanism of electrophilic allylation of α-selective cobalt alkenyl intermediate was proposed based on deuterium labeling experiment and kinetic studies.

Selectively generating “skipped” dienes, where two carbon–carbon double bonds are separated by a saturated carbon center, is an interesting problem in organic chemistry, with few reliable, catalytic methods currently available. Here, the authors report branched selective hydroallylation of terminal alkynes with allylic bromides to form skipped dienes, via cobalt catalysis.

Ligand-Controlled Cobalt-Catalyzed Regiodivergent Alkyne Hydroalkylation

Regiodivergent alkyne hydroalkylation to generate different isomers of an alkene from the same alkyne starting material would be beneficial; however, it remains a challenge. Herein, we report a ligand-controlled cobalt-catalyzed regiodivergent alkyne hydroalkylation. The sensible selection of bisoxazoline (L1) and pyridine-oxazoline (L8) ligands led to reliable and predictable protocols that provided (E)-1,2-disubstituted and 1,1-disubstituted alkenes with high E/Z stereoselectivity and regioisomeric ratio starting from identical terminal alkyne and alkyl halide substrates and produced trisubstituted alkenes in the case of internal alkynes. This method exhibits a broad scope for terminal and internal alkynes with a wide range of activated and unactivated alkyl halides and shows excellent functional group compatibility.

Divergent Reactivity of α,α-Disubstituted Alkenyl Hydrazones: Bench Stable Cyclopropylcarbinyl Equivalents

Herein we report the divergent reactivity of 2,2-dialkyl-3-(E)-alkenyl N-tosylhydrazones using Pd-catalyzed cross-coupling conditions, which enable the Z-selective synthesis of 3-aryl-1,4-dienes and gem-dialkyl vinylcyclopropanes. We found that the dialkylbiaryl phosphine ligand SPhos was the optimal ligand for this transformation producing skipped dienes in up to 83% isolated yield. The ratio of skipped diene to vinylcyclopropane is dependent on both the structure of the α,α-disubstituted hydrazones and the aryl halide partner. Using sterically encumbered aryl bromides provided the trans-cyclopropane products selectively in up to 69% yield. The reaction is stereospecific and stereoselective and occurs alongside a competing 1,2-alkenyl group migration pathway.

Regiodivergent hydroallylation of 1,3-diynes controlled by nickel and palladium catalysts

A highly efficient hydroallylation reaction of 1,3-diynes with allylborons was developed, with the regioselectivity governed primarily by the appropriate choice of the metal.

Palladium-Catalyzed Cascade Allylative Dicarbofunctionalization of Aryl Phenol-Tethered Alkynes with Allyl Iodides: Synthesis of Skipped Dienes

A palladium-catalyzed cascade allylative dicarbofunctionalization of aryl phenol-tethered alkynes with allyl iodides is described. A series of polysubstituted spirocyclo-containing skipped dienes with an all-carbon tetrasubstituted alkene unit are synthesized through this convenient process. The cascade reaction proceeds selectively through dearomative C-allylation instead of O-allylation of aryl phenols.

Reductive hydrobenzylation of terminal alkynes via photoredox and nickel dual catalysis

A photoredox/nickel dual catalyzed reductive hydrobenzylation of alkynes and benzyl chlorides by employing alkyl amines as a stoichiometric reductant is described. This synergistic protocol proceeds via Markovnikov-selective migratory insertion of an alkyne into nickel hydride, followed by cross-coupling with benzyl chloride, providing facile access to important 1,1-disubstituted olefins. This reaction enables the generation of nickel hydride by utilizing readily available alkyl amines as the hydrogen source. The mild conditions are compatible with a wide range of aryl and alkyl alkynes as well as chlorides.

Rhodium-Catalyzed Regio- and Enantioselective Allylic Amination of Racemic 1,2-Disubstituted Allylic Phosphates

Alkynylphosphines are rarely used as ligands in asymmetric metal catalysis. We synthesized a series of chiral bis(oxazoline)alkynylphosphine ligands and used them in Rh-catalyzed highly regio- and enantioselective allylic amination reactions of 1,2-disubstituted allylic phosphates. Chiral 1,2-disubstituted allylic amines were synthesized in up to 95% yield with >20:1 branched/linear (b/l) ratio and 99% ee from racemic 1,2-disubstituted allylic precursors. The sterically smaller linear alkynyl group on the P atom in the bis(oxazoline)alkynylphosphine ligands was the key to fit the new requirements of the introduction of bulky 2-R' groups.

Nickel-Catalyzed Migratory Hydrocyanation of Internal Alkenes: Unexpected Diastereomeric-Ligand-Controlled Regiodivergence

A regiodivergent nickel-catalyzed hydrocyanation of a broad range of internal alkenes involving a chain-walking process is reported. When appropriate diastereomeric biaryl diphosphite ligands are applied, the same starting materials can be converted to either linear or branched nitriles with good yields and high regioselectivities. DFT calculations suggested that the catalyst architecture determines the regioselectivity by modulating electronic and steric interactions. In addition, moderate enantioselectivities were observed when branched nitriles were produced.

Organoborohydride-catalyzed Chichibabin-type C4-position alkylation of pyridines with alkenes assisted by organoboranes

The first NaBEt₃H-catalyzed intermolecular Chichibabin-type alkylation of pyridine and its derivatives with alkenes as the latent nucleophiles is presented with the assistance of BEt₃, and a series of branched C4-alkylation pyridines, even highly congested all-carbon quaternary center-containing triarylmethanes can be obtained in a regiospecific manner. Therefore, the conventional reliance on high cost and low availability transition metal catalysts, prior formation of N-activated pyridines, organometallic reagents, and extra oxidation operation for the construction of a C–C bond at the C4-position of the pyridines in previous methods are not required. The corresponding mechanism and the key roles of the organoborane were elaborated by the combination of H/D scrambling experiments, ¹¹B NMR studies, intermediate trapping experiments and computational studies. This straightforward and mechanistically distinct organocatalytic technology not only opens a new door for the classical but still far less well-developed Chichibabin-type reaction, but also sets up a new platform for the development of novel C–C bond-forming methods.

The first NaBEt₃H-catalyzed intermolecular Chichibabin-type alkylation of pyridines with alkenes as the latent nucleophiles is presented in the presence of BEt₃, and a series of branched C4-alkylated pyridines were obtained in a regiospecific manner.

Sulfonate N-Heterocyclic Carbene-Copper Complexes: Uniquely Effective Catalysts for Enantioselective Synthesis of C-C, C-B, C-H, and C-Si Bonds

A copper-based complex that contains a sulfonate N-heterocyclic carbene ligand was first reported 15 years ago. Since then, these organometallic entities have proven to be uniquely effective in catalyzing an assortment of enantioselective transformations, including allylic substitutions, conjugate additions, proto-boryl additions to alkenes, boryl and silyl substitutions, hydride-allyl additions to alkenyl boronates, and additions of boron-containing allyl moieties to N-H ketimines. In this review article, we detail the shortcomings in the state-of-the-art that fueled the development of this air stable ligand class, members of which can be prepared on multigram scale. For each reaction type, when relevant, the prior art at the time of the advance involving sulfonate NHC-Cu catalysts and/or subsequent key developments are briefly analyzed, and the relevance of the advance to efficient and enantioselective total or formal synthesis of biologically active molecules is underscored. Mechanistic analysis of the structural attributes of sulfonate NHC-Cu catalysts that are responsible for their ability to facilitate transformations with high efficiency as well as regio- and enantioselectivity are detailed. This review contains several formerly undisclosed methodological advances and mechanistic analyses, the latter of which constitute a revision of previously reported proposals.

Catch It If You Can: Copper-Catalyzed (Transfer) Hydrogenation Reactions and Coupling Reactions by Intercepting Reactive Intermediates Thereof

The key reactive intermediate of copper(I)-catalyzed alkyne semihydrogenations is a vinylcopper(I) complex. This intermediate can be exploited as a starting point for a variety of trapping reactions. In this manner, an alkyne semihydrogenation can be turned into a dihydrogen­-mediated coupling reaction. Therefore, the development of copper-catalyzed (transfer) hydrogenation reactions is closely intertwined with the corresponding reductive trapping reactions. This short review highlights and conceptualizes the results in this area so far, with H2-mediated carbon–carbon and carbon–heteroatom bond-forming reactions emerging under both a transfer hydrogenation setting as well as with the direct use of H2. In all cases, highly selective catalysts are required that give rise to atom-economic multicomponent coupling reactions with rapidly rising molecular complexity. The coupling reactions are put into perspective by presenting the corresponding (transfer) hydrogenation processes first.

1 Introduction: H2-Mediated C–C Bond-Forming Reactions

2 Accessing Copper(I) Hydride Complexes as Key Reagents for Coupling Reactions; Requirements for Successful Trapping Reactions

3 Homogeneous Copper-Catalyzed Transfer Hydrogenations

4 Trapping of Reactive Intermediates of Alkyne Transfer Semi­hydrogenation Reactions: First Steps Towards Hydrogenative Alkyne Functionalizations

5 Copper(I)-Catalyzed Alkyne Semihydrogenations

6 Copper(I)-Catalyzed H2-Mediated Alkyne Functionalizations; Trapping of Reactive Intermediates from Catalytic Hydrogenations

6.1 A Detour: Copper(I)-Catalyzed Allylic Reductions, Catalytic Generation of Hydride Nucleophiles from H2

6.2 Trapping with Allylic Electrophiles: A Copper(I)-Catalyzed Hydro­allylation Reaction of Alkynes

6.3 Trapping with Aryl Iodides

7 Conclusion