Quinim: A New Ligand Scaffold Enables Nickel-Catalyzed Enantioselective Synthesis of α-Alkylated γ-Lactam

Cobalt-Catalyzed Enantioselective Reductive α-Chloro-Carbonyl Addition of Ketimine to Construct the β-Tertiary Amino Acid Analogues

β-Tertiary amino acid derivatives constitute one of the most frequently occurring units in natural products and bioactive molecules. However, the efficient asymmetric synthesis of this motif still remains a significant challenge. Herein, we disclose a cobalt-catalyzed enantioselective reductive addition reaction of ketimine using α-chloro carbonyl compound as a radical precursor, providing expedient access to a diverse array of enantioenriched β-quaternary amino acid analogues. This protocol exhibits outstanding enantioselectivity and broad substrate scope with excellent functional group tolerance. Preliminary mechanism studies rule out the possibility of Reformatsky-type addition and confirm the involvement of radical species in stereoselective addition process. The synthetic utility has been demonstrated through the rapid assembly of iterative amino acid units and oligopeptide, showcasing its versatile platform for late-stage modification of drug candidates.

Ligand-Controlled, Nickel-Catalyzed Stereodivergent Construction of 1,3-Nonadjacent Stereocenters

In contrast to the asymmetric synthesis of molecules with a single stereocenter or 1,2-adjacent stereocenters, the simultaneous construction of acyclic 1,3-nonadjacent stereocenters via a single catalyst in an enantioselective and diastereoselective manner remains a formidable challenge. Here, we demonstrate the enantioselective and diastereodivergent construction of 1,3-nonadjacent stereocenters through Ni-catalyzed reductive cyclization/cross-coupling of alkene-tethered aryl bromides and α-bromoamides, which represents the major remaining stereochemical challenge of cyclization/difunctionalization of alkenes. Using Ming-Phos as ligand, a diverse set of oxindoles containing 1,3-nonadjacent stereocenters were obtained with high levels of enantio- and diastereoselectivity. Mechanistic experiments and density functional theory calculations indicate that magnesium salt plays a key role in controlling the diastereoselectivity. Furthermore, another set of complementary stereoisomeric products were constructed from the same set of starting materials using Ph-Phox as ligand.

Ni-catalyzed enantioconvergent deoxygenative reductive cross-coupling of unactivated alkyl alcohols and aryl bromides

Transition metal-catalyzed enantioconvergent cross-coupling of an alkyl precursor presents a promising method for producing enantioenriched C(sp3) molecules. Because alkyl alcohol is a ubiquitous and abundant family of feedstock in nature, the direct reductive coupling of alkyl alcohol and aryl halide enables efficient access to valuable compounds. Although several strategies have been developed to overcome the high bond dissociation energy of the C - O bond, the asymmetric pattern remains unknown. In this report, we describe the realization of an enantioconvergent deoxygenative reductive cross-coupling of unactivated alkyl alcohol (β-hydroxy ketone) and aryl bromide in the presence of an NHC activating agent. The approach can accommodate substituents of various sizes and functional groups, and its synthetic potency is demonstrated through a gram scale reaction and derivatizations into other compound families. Finally, we apply our convergent method to the efficient asymmetric synthesis of four β-aryl ketones that are natural products or bioactive compounds.

Nickel-Catalyzed Deoxygenative Amidation of Alcohols with Carbamoyl Chlorides

We report a deoxygenative amidation reaction of alcohols with carbamoyl chlorides to afford amides through nickel-photoredox dual catalysis. Good to excellent yields can be obtained even for diverse complex sugar and steroid derivatives. The reaction is scalable, and the synthetic utility of the reaction was demonstrated by the homologation of alcohols to deliver several important γ-amino alcohols and a synthetically challenging bioactive compound intermediate.

Cobalt-Catalyzed Asymmetric Aza-Nozaki-Hiyama-Kishi (NHK) Reaction of α-Imino Esters with Alkenyl Halides

Chromium-catalyzed enantioselective Nozaki-Hiyama-Kishi (NHK) reaction represents one of the most powerful approaches for the formation of chiral carbon-heteroatom bond. However, the construction of sterically encumbered tetrasubstituted stereocenter through NHK reaction still posts a significant challenge. Herein, we disclose a cobalt-catalyzed aza-NHK reaction of ketimine with alkenyl halide to provide a convenient synthetic approach for the manufacture of enantioenriched tetrasubstituted α-vinylic amino acid. This protocol exhibits excellent functional group tolerance with excellent 99 % ee in most cases. Additionally, this asymmetric reductive method is also applicable to the aldimine to access the trisubstituted stereogenic centers.

Dual Photoredox/Nickel Catalysis Enables Diastereoselective Synthesis of Multisubstituted γ-Lactams Using Alkyl-GeMe3 as Radical Precursors

Herein, we report a single-step, multicomponent approach to versatile γ-lactams through dual photoredox/nickel-catalyzed dicarbofunctionalization of α,β-unsaturated γ-butyrolactam. This reaction utilized alkyl trimethylgermanium as a radical precursor and acyl chloride as the electrophile, demonstrating remarkable functional group compatibility.

Nickel-Catalyzed Asymmetric Propargyl-Aryl Cross-Electrophile Coupling

Performing asymmetric cross-coupling reactions between propargylic electrophiles and aryl nucleophiles is a well-established method to build enantioenriched benzylic alkynes. Here, a catalytic enantioselective propargyl-aryl cross-coupling between two electrophiles was achieved for the first time in a stereoconvergent manner. Propargylic chlorides were treated with aryl iodides as well as heteroaryl iodides in the presence of a chiral nickel complex, and manganese metal was used as a stoichiometric reductant, allowing for the construction of a propargyl C-aryl bond under mild conditions. An alternative dual nickel/photoredox catalytic protocol was also developed for this cross-electrophile coupling in the absence of a metal reductant. The potential utility of this conversion is demonstrated in the facile construction of stereoenriched bioactive molecule derivatives and medicinal compounds based on the diversity of acetylenic chemistry. Detailed experimental studies have revealed the key mechanistic features of this transformation.

From Conventional to Sustainable Catalytic Approaches for Heterocycles Synthesis

Synthesis of heterocyclic compounds is fundamental for all the research area in chemistry, from drug synthesis to material science. In this framework, catalysed synthetic methods are of great interest to effective reach such important building blocks. In this review, we will report on some selected examples from the last five years, of the major improvement in the field, focusing on the most important conventional catalytic systems, such as transition metals, organocatalysts, to more sustainable ones such as photocatalysts, iodine-catalysed reaction, electrochemical reactions and green innovative methods.

Straightforward synthesis of functionalized γ-Lactams using impure CO2 stream as the carbon source

Direct utilization of CO2 into organic synthesis finds enormous applications to synthesize pharmaceuticals and fine chemicals. However, pure CO2 gas is essential to achieve these transformations, and the purification of CO2 is highly cost and energy intensive. Considering this, we describe a straightforward synthetic route for the synthesis of γ-lactams, a pivotal core structure of bioactive molecules, by using commercially available starting materials (alkenes and amines) and impure CO2 stream (exhaust gas is collected from the car) as the carbon source. This blueprint features a broad scope, excellent functional group compatibility and application to the late-stage transformation of existing pharmaceuticals and natural products to synthesize functionalized γ-lactams. We believe that our strategy will provide direct access to γ-lactams in a very sustainable way and will also enhance the Carbon Capture and Utilization (CCU) strategy.

Divergent and Selective Light Alkene Cross-Coupling

Light olefins are abundantly manufactured in the petroleum industry and thus represent ideal starting materials for modern chemical synthesis. Selective and divergent transformations of feedstock light olefins to value-added chemicals are highly sought-after but remain challenging. Herein we report an exceptionally regioselective carbonickelation of light alkenes followed by in situ trapping with three types of nucleophiles, namely a reductant, base, or Grignard reagent. This protocol enables efficient 1,2-hydrofunctionalization, dicarbofunctionalization, and branched-selective Heck-type cross-coupling of light alkenes with aryl and alkenyl reagents to streamline access to diverse alkyl arenes and complex alkenes. Harnessing bulky N-heterocyclic carbene ligands with acenaphthyl backbones for nickel catalysts is crucial to attain high reactivity and selectivity. This strategy provides a rare, modular, and divergent platform for upgrading feedstock alkenes and is expected to find broad applications in medicinal chemistry and industrial processes.

Nickel-catalyzed acylzincation of allenes with organozincs and CO

Transition metal-catalyzed carbonylative reaction with CO gas are among the central task in organic synthesis, enabling the construction of highly valuable carbonyl compound. Here, we show an earth-abundant nickel-catalyzed three-component tandem acylzincation/cyclization sequence of allene and alkylzinc reagent with 1 atm of CO under mild conditions. This protocol is featured by broad functional group tolerance with high reaction selectivity, providing a rapid and convenient synthetic method for the construction of diverse fully substituted benzotropone derivatives. Mechanistic studies reveal that the installation of a cyano group tethered to allene moiety enables the high regio- and stereoselectivity of this acylzincation of allene, allowing the selective formation of three consecutive C-C bonds in a highly efficient manner.

Electrochemical NiH-Catalyzed C(sp3 )-C(sp3 ) Coupling of Alkyl Halides and Alkyl Alkenes

Herein, an electrochemically driven NiH-catalyzed reductive coupling of alkyl halides and alkyl alkenes for the construction of Csp3 -Csp3 bonds is firstly reported. Notably, alkyl halides serve dual function as coupling substrates and as hydrogen sources to generate NiH species under electrochemical conditions. The tunable nature of this reaction is realized by introducing an intramolecular coordinating group to the substrate, where the product can be easily adjusted to give the desired branched products. The method proceeds under mild conditions, exhibits a broad substrate scope, and affords moderate to excellent yields with over 70 examples, including late-stage modification of natural products and drug derivatives. Mechanistic insights offer evidence for an electrochemically driven coupling process. The sp3 -carbon-halogen bonds can be activated through single electron transfer (SET) by the nickel catalyst in its low valence state, generated by cathodic reduction, and the generation of NiH species from alkyl halides is pivotal to this transformation.

Nickel-Catalyzed Asymmetric Decarboxyarylation with NHP Esters of α-Amino Acid to Chiral Benzylamines

A nickel-catalyzed asymmetric decarboxyarylation of NHP esters via reductive cross-coupling has been established. Utilizing the NHP of amino acid esters as radical precursors furnishes a new protocol in which structurally diverse chiral benzylamines could be accessible. This method has demonstrated excellent catalytic efficiency, high enantioselective control, mild conditions, and good functional group tolerance, thus enabling the late-stage modification of bioactive molecules and pharmaceuticals.

Palladium-catalyzed Heck-carbonylation of alkene-tethered carbamoyl chlorides with aryl formates

We report a palladium-catalyzed Heck-carbonylation of alkene-tethered carbamoyl chlorides by utilizing aryl formates as convenient CO surrogates. One C-O and two C-C bonds are constructed to give diversiform esterified oxindoles/γ-lactams bearing an all-carbon quaternary stereocenter under gas-free conditions. This transformation features a wide substrate scope and good functional group tolerance and can be easily applied to late-stage functionalization.

Ni-Catalyzed Enantioselective Intramolecular Mizoroki-Heck Reaction for the Synthesis of Phenanthridinone Derivatives

A Ni-catalyzed enantioselective intramolecular Mizoroki-Heck reaction has been developed to transform symmetrical 1,4-cyclohexadienes with attached aryl halides into phenanthridinone analogues containing quaternary stereocenters. Herein, we report important advances in reaction optimization enabling control of unwanted proto-dehalogenation and alkene reduction side products. Moreover, this approach provides direct access to six-membered ring heterocyclic systems bearing all-carbon quaternary stereocenters, which have been much more challenging to form enantioselectively with nickel-catalyzed Heck reactions. A wide range of substrates were demonstrated to work in good to excellent yields. Good enantioselectivity was demonstrated using a new synthesized chiral iQuinox-type bidentate ligand (L27). The sustainability, low price of nickel catalysts, and significantly faster reaction rate (1 h) versus that of a recently reported palladium-catalyzed reaction (20 h) make this process an attractive alternative.

Ligand-enabled Ni-catalysed enantioconvergent intermolecular Alkyl-Alkyl cross-coupling between distinct Alkyl halides

α-Tertiary aliphatic amides are key elements in organic molecules, which are abundantly present in natural products, pharmaceuticals, agrochemicals, and functional organic materials. Enantioconvergent alkyl-alkyl bond-forming process is one of the most straightforward and efficient, yet highly challenging ways to build such stereogenic carbon centers. Herein, we report an enantioselective alkyl-alkyl cross-coupling between two different alkyl electrophiles to access α-tertiary aliphatic amides. With a newly-developed chiral tridentate ligand, two distinct alkyl halides were successfully cross-coupled together to forge an alkyl-alkyl bond enantioselectively under reductive conditions. Mechanistic investigations reveal that one alkyl halides exclusively undergo oxidative addition with nickel versus in-situ formation of alkyl zinc reagents from the other alkyl halides, rendering formal reductive alkyl-alkyl cross-coupling from easily available alkyl electrophiles without preformation of organometallic reagents.

Nickel-Catalyzed Ligand-Controlled Selective Reductive Cyclization/Cross-Couplings

ConspectusThe use of quaternary stereocenters during lead candidate optimization continues to grow because of improved physiochemical and pharmacokinetic profiles of compounds with higher sp³ fraction. Pd-catalyzed redox-neutral alkene difunctionalization involving carbopalladation of alkenes followed by nucleophilic-trapping σ-alkyl-palladium intermediates has been developed as an efficient method to construct quaternary stereocenters. However, the low chemoselectivity and air sensitivity of organometallic nucleophiles, as well as their low availability and accessibility, limit the scope of application of this elegant strategy. Recently, Ni-catalyzed reductive cross-coupling has evolved into a privileged strategy to easily construct valuable C(sp³)-C bonds. Despite great progress, the enantioselective coupling of C(sp³) electrophiles still relies on activated or functionalized alkyl precursors, which are often unstable and require multiple steps to prepare. Therefore, Ni-catalyzed reductive difunctionalization of alkenes via selective cyclization/cross-coupling was developed. This strategy not only offers a robust and practical alternative for traditional redox-neutral alkene difunctionalization but also provides strategic complementarity for reductive cross-coupling of activated alkyl electrophiles. In this Account, we summarize the latest results from our laboratory on this topic. These findings mainly include our explorations in modulating the enantioselectivity and cyclization mode of reductive cyclization/cross-couplings.We will first discuss Ni-catalyzed enantioselective reductive cyclization/cross-coupling to construct valuable chiral heterocycles with quaternary stereocenters and focus on the effects of ligands, reductants, and additives and their roles in reductive cross-coupling. A wide range of electrophiles have been explored, including aryl halides, vinyl halides, alkynyl halides, gem-difluoroalkenes, CO₂, trifluoromethyl alkenes, and cyano electrophiles. The synthetic potential of this approach has also been demonstrated in the synthesis of biologically active natural products and drug molecules. Second, we will detail how to tune the steric effects of nickel catalysts by modifying bipyridine ligands for regiodivergent cyclization/cross-couplings. Specifically, the use of bidentate ligands favors exo-selective cyclization/cross-coupling, while the use of a carboxylic acid-modified bipyridine ligand permits endo-selective cyclization/cross-coupling. We will also show how to activate the amide substrate by altering the electronic and steric properties of substituents on the nitrogen, thereby enabling the nucleophilic addition of aryl halides to amide carbonyls. Further investigation of ligand properties has led to tunable cyclization/cross-couplings (addition to the amide carbonyl vs 7-endo-cyclization) for the divergent synthesis of pharmacologically important 2-benzazepine frameworks. Finally, we serendipitously discover that modifying the ligands of nickel catalysts and changing the oxidation state of nickel can control the migratory aptitude of different groups, thus providing a switchable skeletal rearrangement strategy. This transformation is of high synthetic value because it represents a conceptually unprecedented new approach to C-C bond activation. Thus, this Account not only summarizes synthetic methods that allow the formation of valuable chiral heterocycles with quaternary stereocenters using a wide variety of electrophiles but also provides insight into the relationship between ligand structure, substrate, and cyclization selectivity.

Merging Alkene Isomerization Enables Difunctionalization of Cyclic Enamines toward Ring-Fused Aminal Synthesis

Here we report a Pd-catalyzed isomerization of alicyclic allyl amine to achieve the unprecedented α,β-difunctionalization of synthetically inaccessible trisubstituted cyclic enamine. The dual role of in situ formed enamine intermediate allows for the intermolecular formal [4 + 2] reaction with acrylamide or isatoic anhydride to simultaneously construct the C-C bond and C-N bond, thus realizing the expedient construction of [4.3.0]-aminal with excellent diastereoselectivity and high atom economy.

A general nickel-catalyzed highly regioselective hydroarylation of unactivated alkenes enabled by the picolinamide auxiliary

A practical method for regioselective hydroarylation of unactivated γ- or δ-vinyl alkylamines has been reported, enabling facile preparation of highly value-added ε- or ζ-aryl alkylamines. The protocol employs nickel catalysis, shows high functional group tolerance and can be used for modifying bio-related molecules.

Photoredox-Catalyzed Tandem Radical Cyclization/Hydroxylation for the Synthesis of 4-Hydroxyalkyl-3,3-difluoro-γ-lactams

The photoredox-catalyzed radical difluoroalkylation/cyclization/hydroxylation cascade reaction of various 2-bromo-2,2-difluoro-N-arylacetamides containing unactivated alkene moieties has been developed, providing green and efficient access to various 4-hydroxyalkyl-3,3-difluoro-γ-lactams. Control experiments confirmed a radical process, and inexpensive air acted as the sole hydroxy resource. In addition, the highlights of this protocol include good tolerance for a variety functional groups, lower photocatalyst loading, and ease of operation.

Ni-catalyzed carbamoylation of unactivated alkenes for stereoselective construction of six-membered lactams

Nitrogen-based heterocycles have aroused widespread interest due to their reoccurrence in many pharmaceuticals. Amongst these motifs, the enantioenriched lactams are the ubiquitous scaffolds found in myriad biologically active natural products and drugs. Recently, the transition metal-catalyzed asymmetric carbamoylation has been widely employed as a straightforward arsenal for chiral lactam architecture synthesis, including β-lactam and γ-lactam. However, despite the extensive efforts, there still remains no protocol to accomplish the related δ-lactam synthesis. In this manuscript, the Ni-catalyzed enantioselective carbamoylation of unactivated alkenes by the leverage of reductive dicarbofunctionalization strategy allows for the expedient access to two types of mostly common six-membered lactams: 3,4-dihydroquinolinones and 2-piperidinone in high yield and enantioselectivity. This protocol features with good functional group tolerance, as well as broad substrate scope. The newly developed chiral 8-Quinox skeleton ligand is the key parameter for this transformation, which significantly enhances the reactivity and enantioselectivity.

Six-membered chiral lactams are common structural motifs of pharmaceuticals. Here, the authors describe a nickel-catalyzed reductive carbamoylation of alkenes to form enantioenriched six-membered lactams.

Nickel-Catalyzed Reductive Dicarbofunctionalization of Vinylarenes Enabled by Electrochemical Process

An intermolecular alkene dicarbofunctionalization via electrochemical reduction that combines alkyl and aryl iodides with styrene derivatives was herein reported. The multicomponent reaction exhibited several synthetic advantages including simple operation, wide substrate scope, and convenience of amplification. Mechanistic investigations, including cyclic voltammetry (CV), electron paramagnetic resonance (EPR), and radical trapping reactions, support the electrochemical nickel catalytic cycle and formation of alkyl radical species from alkyl iodides.

Nickel(II)-catalyzed highly selective 1,2-diborylation of non-activated monosubstituted alkenes

A practical method for 1,2-diborylation of non-activated monosubstituted alkenes via nickel catalysis has been developed. The protocol features high functional group tolerance and can be applied for the formal synthesis of drugs and modification of natural product derivatives. Preliminary mechanistic studies imply the involvement of a Ni(II) catalytic cycle.

Nickel-Catalyzed Enantioselective Reductive Alkyl-Carbamoylation of Internal Alkenes

Herein, we leverage the Ni-catalyzed enantioselective reductive dicarbofunctionalization of internal alkenes with alkyl iodides to enable the synthesis of chiral pyrrolidinones bearing vicinal stereogenic centers. The application of newly developed 1-Nap Quinim is critical for formation of two contiguous stereocenters in high yield, enantioselectivity, and diastereoselectivity. This catalytic system also improves both the yield and enantioselectivity in the synthesis of α,α-dialkylated γ-lactams. Computational studies reveal that the enantiodetermining step proceeds with a carbamoyl-NiI intermediate that is reduced by the Mn reductant prior to intramolecular migratory insertion. The presence of the t-butyl group of the Quinim ligand leads to an unfavorable distortion of the substrate in the TS that leads to the minor enantiomer. Calculations also support an improvement in enantioselectivity with 1-Nap Quinim compared to p-tol Quinim.

Palladium(II)-catalyzed enantioselective intermolecular oxidative diarylation of internal enamides

The construction of vicinal stereogenic centers via the simultaneous formation of two C-C bonds across alkenes under oxidative conditions is a stubborn challenge. Herein, we report a Pd(II)-catalyzed highly enantioselective intermolecular oxidative 1,2-diarylation reaction of internal enamides with aryl boronic acids, enabling the expedient construction of two vicinal stereocenters with excellent diastereo-, and enantioselectivities.

Enantioselective Reductive N-Cyclization-Alkylation Reaction of Alkene-Tethered Oxime Esters and Alkyl Iodides by Nickel Catalysis

Asymmetric cross-electrophile difunctionalization of tethered alkenes has become a powerful tool for the production of chiral cyclic scaffolds; however, the current studies all focus on carbocyclization reactions. Herein, we report an N-cyclization-alkylation reaction and thus showcase the potential of heterocyclization for accessing new enantioenriched cyclic architectures. This work establishes a new approach for enantioselective aza-Heck cyclization/cross-coupling sequence, which remains a long-standing unsolved challenge for the synthetic community. The reaction proceeds with primary, secondary, and a few tertiary alkyl iodides, and the use of newly defined ligands gave highly enantioenriched pyrrolines with improved molecular diversity under mild conditions. The presence of imine functionality allows for further structural variations.

Catalytic Desymmetric Dicarbofunctionalization of Unactivated Alkenes

The construction of multi-stereocenters by a transition metal-catalyzed cross-coupling reaction is a major challenge. The catalytic desymmetric functionalization of unactivated alkenes remains largely unexplored. Herein, we disclose -a desymmetric dicarbofunctionalization of 1,6-dienes via a nickel-catalyzed reductive cross-coupling reaction. The leverage of the underdeveloped chiral 8-Quinox enables the Ni-catalyzed desymmetric carbamoylalkylation of both unactivated mono- and disubstituted alkenes to form pyrrolidinone bearing two nonadjacent stereogenic centers in high enantio- and stereoselectivitives with broad functional-group tolerance. The synthetic application of pyrrolidinones allows the rapid access to complex chiral fused-heterocycles.

Nickel-Catalyzed Three-Component Alkylacylation of Alkenes Enabled by a Photoactive Electron Donor-Acceptor Complex

An electron donor-acceptor complex-enabled, nickel-catalyzed three-component net-reductive 1,2-alkylacylation of alkenes is developed. This conjunctive reductive acyl cross-coupling process obviates the use of an exogenous photocatalyst and a stoichiometric metal-based reductant, affording various synthetically useful 1,3-dicarbonyl compounds in good yields with a broad substrate scope and excellent functional group tolerance. Both alkyl and acyl electrophiles are derived from the highly abundant and readily accessible carboxylic acids, making the catalytic 1,2-dicarbofunctionalization more synthetically general and sustainable.

Ni-Catalyzed enantioselective reductive arylcyanation/cyclization of N-(2-iodo-aryl) acrylamide

A Ni/(S,S)-BDPP-catalyzed intramolecular Heck cyclization of N-(2-iodo-aryl) acrylamide with 2-methyl-2-phenylmalononitrile was developed to give oxindoles with good enantioselectivities. We found that utilizing such an electrophilic cyanation reagent could tackle the deleterious effect of the coordinative cyanide ion in the asymmetric alkene arylcyanation.

Asymmetric synthesis of chiral imidazolidines by merging copper and visible light-induced photoredox catalysis

A visible light induced copper catalyzed synthesis of decarboxylative radical coupling/cyclization reaction for the synthesis of chiral imidazolidines in high yields and enantioselectivities was reported.

Chemo-selective control of Ritter-type reaction by coordinatively unsaturated inorganic salt hydrates

We used a readily available water source, MgSO4·2H2O, to realize the control of the chemo-selectivity of the Ritter-type reaction efficiently.

Manganese-mediated reductive N,N-dialkylation of nitroarenes: a dramatic NiI2 effect

A dramatic NiI2 effect has been found for Mn-mediated reductive N,N-dialkylation of nitroaromatics.

Isothiourea-Catalysed Enantioselective Radical Conjugate Addition under Batch and Flow Conditions

The photocatalytic generation of α-amino radicals is combined with chiral isothiourea derived α,β-unsaturated acyl ammonium intermediates. The reaction proceeds via a [3+2] radical-polar crossover mechanism to generate γ-lactams in good...

Three-Component Visible-Light-Induced Palladium-Catalyzed 1,2-Alkyl Carbamoylation/Cyanation of Alkenes

A mild visible-light-induced Pd-catalyzed one-pot three-component alkyl-carbamoylation and cyanation of alkenes was developed. This general transformation, which proceeds via the in situ formation of a reactive ketenimine intermediate, allows for a rapid construction of a broad range of valuable amides and nitriles from readily available alkenes, alkyl iodides, and isocyanides. An efficient synthesis of tetrazole and amidine via this approach was also demonstrated.

Nickel-Catalyzed Multicomponent Coupling: Synthesis of α-Chiral Ketones by Reductive Hydrocarbonylation of Alkenes

A nickel-catalyzed, multicomponent regio- and enantioselective coupling via sequential hydroformylation and carbonylation from readily available starting materials has been developed. This modular multicomponent hydrofunctionalization strategy enables the straightforward reductive hydrocarbonylation of a broad range of unactivated alkenes to produce a wide variety of unsymmetrical dialkyl ketones bearing a functionalized α-stereocenter, including enantioenriched chiral α-aryl ketones and α-amino ketones. It uses chiral bisoxazoline as a ligand, silane as a reductant, chloroformate as a safe CO source, and a racemic secondary benzyl chloride or an N-hydroxyphthalimide (NHP) ester of a protected α-amino acid as the alkylation reagent. The benign nature of this process renders this method suitable for late-stage functionalization of complex molecules.

Enantioselective Reductive Divinylation of Unactivated Alkenes by Nickel-Catalyzed Cyclization Coupling Reaction

Catalytic asymmetric dicarbofunctionalization of tethered alkenes has emerged as a promising tool for producing chiral cyclic molecules; however, it typically relies on aryl-tethered alkenes to form benzene-fused compounds. Herein, we report an enantioselective cross-electrophile divinylation reaction of nonaromatic substrates, 2-bromo-1,6-dienes. The approach thus offers a route to new chiral cyclic architectures, which are key structural motifs found in various biologically active compounds. The reaction proceeds under mild conditions, and the use of chiral t-Bu-pmrox and 3,5-difluoro-pyrox ligands resulted in the formation of divinylated products with high chemo-, regio-, and enantioselectivity. The method is applicable for the incorporation of chiral hetero- and carbocycles into complex molecules.

Pd-Catalyzed Asymmetric Acyl-Carbamoylation of an Alkene to Construct an α-Quaternary Chiral Cycloketone

Herein, we report the palladium-catalyzed asymmetric acyl-carbamoylation of an alkene by employing thioesters as the acyl electrophiles and t-BuNC as the carbamoyl reagent, affording an α-quaternary chiral cycloketone in synthetically useful yields with excellent enantioselectivity. The reaction proceeded via asymmetric 1,2-migratory insertions of acyl-Pd into alkenes and subsequent migratory insertion of isocyanides into C(sp³)-Pd^II. The product could be diversified to some valuable skeletons with retention of enantiopurity, demonstrating the synthetic utility of this protocol.

Nickel-Catalyzed Asymmetric Reductive Dicarbamoylation of Alkenes

Herein we report a nickel-catalyzed asymmetric reductive dicarbamoylation of alkenes, in which tethered carbamoyl chlorides and isocyanates serve as distinct electrophilic carbamoylating agents, providing new access to chiral oxindoles bearing an amide-substituted quaternary stereogenic center.