Palladium-catalyzed intermolecular aminocarbonylation of alkenes: efficient access of β-amino acid derivatives

Copper-Catalyzed Selective Amino-alkoxycarbonylation of Unactivated Alkenes with CO

1,2-Amino-difunctionalization reactions of alkenes allow the efficient introduction of different functional groups and the rapid construction of valuable functionalized amines. In this respect, we report a copper-catalyzed 1,2-amino-alkoxycarbonylation of unactivated alkenes with CO and alkylamine precursors in the presence of a Lewis acid additive. The novel protocol allows direct access to valuable β-amino acid derivatives from easily available starting materials. The presented methods feature high chemo- and regioselectivities, good functional group tolerance, and substrate scope including diverse bioactive compounds and drug-like molecules. Mechanistic studies indicate that the Lewis acid additive is the key to realizing the efficient umpolung addition of nucleophilic aminyl radicals to electron-rich alkenes, which represents an elegant activation strategy for aminyl radicals.

Nickel-Catalyzed Three-Component Carboamination/Cyclization of Alkynes To Access 2,3-Disubstituted Quinolines

Presented herein is a nickel-catalyzed chemo- and regioselective three-component tandem carboamination and cyclization of terminal alkynes with organoboronic acids and anthranils for facile and modular access to 2,3-substituted quinolines. In this process, anthranil has dual roles: serving as an electrophilic aminating reagent and a redox buffer to suppress the generation of an off-cycle Ni(0) complex. Moreover, the anionic acetylacetonate (acac) ligand was found to be vital to ensure a productive Ni(I)-Ni(III)-Ni(I) catalytic cycle.

Regioselective intermolecular carboamination of allylamines via nucleopalladation: empowering three-component synthesis of vicinal diamines

An intermolecular carboamination reaction of allyl amines under Pd(ii)-catalysis is reported, expediting the synthesis of valuable vicinal diamines embedded in a functionally enriched linear carbon framework with high yields and exclusive Markovnikov selectivity. Central to our approach is the strategic use of a removable picolinamide auxiliary, which directs the regioselectivity during aminopalladation and stabilizes the crucial 5,5-palladacycle intermediate. This stabilization facilitates oxidative addition to carbon electrophiles, enabling the simultaneous incorporation of diverse aryl/styryl groups as well as important amine motifs, such as sulfoximines and anilines, across carbon-carbon double bonds. The protocol features broad substrate compatibility, tolerance to various functional groups, and scalability. The utility of this method is further demonstrated by the site-selective diversification of pharmaceutical agents. Additionally, these products serve as versatile intermediates for synthesizing heterocycles and function as effective ligands in catalytic transfer hydrogenation reactions. Notably, this work represents a rare instance of nucleopalladation-guided intermolecular carboamination of allylamines.

Photocatalytic synthesis of β-amino acid derivatives from alkenes with alkyl formates

The aminocarbonylation of alkenes is an efficient approach to synthesize important β-amino acid motifs. However, simple and convenient methods are still rare. Herein, we present a novel visible-light-mediated controllable three-component radical relay coupling of alkenes, alkyl formates and oxime esters. By the combination of hydrogen atom transfer and energy transfer processes, a series of β-amino esters could be obtained smoothly in one step under mild conditions. We expect that the approach can complement current methodologies for the synthesis of β-amino esters.

Enantioselective Access to β-Amino Carbonyls via Ni-Catalyzed Formal Olefin Hydroamidation

We herein describe a Ni-catalyzed formal hydroamidation of readily available α,β-unsaturated carbonyl compounds to afford valuable chiral β-amino acid derivatives (up to >99:1 e.r.) using dioxazolones as a robust amino source. A wide range of alkyl-substituted olefins conjugated to esters, amides, thioesters, and ketones were successfully amidated at the β-position with excellent enantioselectivity for the first time. Combined experimental and computational mechanistic studies supported our working hypothesis that this unconventional β-amidation of unsaturated carbonyl substrates can be attributed to the polar-matched migratory olefin insertion of an (amido)(Cl)NiII intermediate, in situ generated from the dioxazolone precursor.

Base mediated aza-[2 + 1] annulation and regioselective aziridine ring-opening cascade: mild synthesis of functionalized β-amino ketones from cyclic N-sulfonyl aldimines and α-carbonyl sulfonium salts

Cyclic N-sulfonyl aldimines are well-known aza-[2C]-synthons for various [2 + n] annulation reactions. Herein we describe a novel base mediated [2 + 1] annulation and a regioselective aziridine ring-opening reaction cascade, which provides an efficient and distinct synthetic strategy from readily available cyclic N-sulfonyl aldimines and α-carbonyl sulfonium salts leading to β-amino ketone derivatives through the corresponding fused tri-substituted aziridines. This one-pot, two-step process involves formation of C-C and C-N bonds and subsequent cleavage of a C-N bond. The features of the developed reaction include the use of mild reaction conditions, broad substrate scope, and excellent yields. The synthetic utility of this approach was demonstrated by gram-scale operation and further product derivatizations.

Rh(III)-Catalyzed Diastereo- and Enantioselective Regiodivergent (Hetero)Arylamidation of (Homo)Allylic Sulfides

A rhodium-catalyzed 3-component conjunctive diastereo- and regioselective arylamidation of (homo)allylic sulfides, organon boronic acids, and dioxazolones is reported. These reactions deliver the 1,2-insertion and 2,1-insertion arylamidation products, respectively, for allylic sulfides and homoallylic sulfides. The enantioselective arylamidation of terminal and internal allylic sulfides is achieved, furnishing various 1,3-N,S compounds featuring one or two contiguous stereocenters in high yields and with high diastereo- and enantioselectivities. Mechanistic studies suggest a change in the turnover-limiting and selectivity-determining steps induced by the native and easily removable sulfide group.

Straightforward Access to Free β2,3,3 -Amino Acids through One Pot C-H Activation/C-C Cleavage

The first synthesis of unnatural β2,3,3 -amino acids with a spirocyclic backbone by one-pot protocol has been presented. This reaction features wide functional group tolerance and feasibility of post-functionalization of natural products and biologically important molecules. Novel dipeptide and tripeptide structures were assembled using this newly developed β2,3,3 -amino acid in high efficiency. The combination of C-H activation and C-C cleavage for the synthesis of β-amino acids would trigger more promising synthetic routes for this compound.

Cu-Catalyzed Polychloromethylamination of Styrenes through C(sp3 )-H Bond Cleavage

A copper-catalyzed three-component coupling reaction has been developed allowing the rapid building of valuable complex highly functionalized β-polychloromethyl amines from simple styrenes, arylamines, and dichloromethane/chloroform. Using aryldiazonium salts as a radical initiator, a series of corresponding products are obtained with moderate to good yields under a carbon dioxide or nitrogen atmosphere (50 psi). In addition, good functional group tolerance can be observed.

Metal-free photosensitized radical relay 1,4-carboimination across two distinct olefins

Intermolecular carboamination of olefins offers a powerful platform for the rapid construction of structurally complex amines from abundant feedstocks. However, these reactions often require transition-metal catalysis, and are mainly limited to 1,2-carboamination. Herein, we report a novel radical relay 1,4-carboimination across two distinct olefins with alkyl carboxylic acid-derived bifunctional oxime esters via energy transfer catalysis. The reaction is highly chemo- and regioselective, and multiple C-C and C-N bonds were formed in a single orchestrated operation. This mild and metal-free method features a remarkably broad substrate scope with excellent tolerance of sensitive functional groups, therefore providing easy access to structurally diverse 1,4-carboiminated products. Moreover, the obtained imines could be easily converted into valuable biologically relevant free γ-amino acids.

Iminoacylation of Alkenes via Photoredox N-Heterocyclic Carbene Catalysis

The iminoacylation of alkenes via photoredox N-heterocyclic carbene catalysis is developed with the employment of alkene-tethered α-imino-oxy acids and acyl imidazoles. The corresponding substituted 3,4-dihydro-2H-pyrroles were afforded in moderate to good yields with good to high diastereoselectivities in most cases. The reaction involves the 5-exo-trig radical cyclization of an alkene-tethered iminyl radical and the following coupling with a ketyl radical from acyl imidazole under NHC catalysis.

N-Amidation of Nitrogen-Containing Heterocyclic Compounds: Can We Apply Enzymatic Tools?

Amide bond is often seen in value-added nitrogen-containing heterocyclic compounds, which can present promising chemical, biological, and pharmaceutical significance. However, current synthesis methods in the preparation of amide-containing N-heterocyclic compounds have low specificity (large amount of by-products) and efficiency. In this study, we focused on reviewing the feasible enzymes (nitrogen acetyltransferase, carboxylic acid reductase, lipase, and cutinase) for the amidation of N-heterocyclic compounds; summarizing their advantages and weakness in the specific applications; and further predicting candidate enzymes through in silico structure-functional analysis. For future prospects, current enzymes demand further engineering and improving for practical industrial applications and more enzymatic tools need to be explored and developed for a broader range of N-heterocyclic substrates.

Pd-Catalyzed Asymmetric 5-exo-trig Cyclization/Cyclopropanation/Carbonylation of 1,6-Enynes for the Construction of Chiral 3-Azabicyclo[3.1.0]hexanes

We herein disclose a mild and efficient access to chiral 3-azabicyclo[3.1.0]hexanes via a Pd-catalyzed asymmetric 5-exo-trig cyclization/cyclopropanation/carbonylation of 1,6-enynes. Various nucleophiles, such as alcohols, phenols, amines and water, are well compatible with the reaction system. This reaction forms three C-C bonds, two rings, two adjacent quaternary carbon stereocenters as well as one C-O/C-N bond with excellent regio- and enantioselectivities. The products could be further functionalized to generate a library of 3-azabicyclo[3.1.0]hexane frameworks.

Metal-free photosensitized intermolecular carboimination of alkenes: a green and direct access to both β-amino acids and β-amino ketones

β-Amino carbonyl substructures are privileged motifs in natural products and active pharmaceutical compounds. Here, we report a photoinduced metal-free and highly regioselective intermolecular carboimination method via the simultaneous introduction of amino and carbonyl groups into the CC double bond in one step, providing straightforward, green and general access to both β-amino acid and β-amino ketone motifs from readily available alkene feedstocks. The mild reaction conditions, excellent functional group tolerance and product diversity should make this a broadly applicable carboimination approach of very broad interest to organic and medicinal chemists.

Photochemical single-step synthesis of β-amino acid derivatives from alkenes and (hetero)arenes

β-Amino acids are frequently found as important components in numerous biologically active molecules, drugs and natural products. In particular, they are broadly utilized in the construction of bioactive peptides and peptidomimetics, thanks to their increased metabolic stability. Despite the number of methodologies established for the preparation of β-amino acid derivatives, the majority of these methods require metal-mediated multistep manipulations of prefunctionalized substrates. Here we disclose a metal-free, energy-transfer enabled highly regioselective intermolecular aminocarboxylation reaction for the single-step installation of both amine and ester functionalities into alkenes or (hetero)arenes. A bifunctional oxime oxalate ester was developed to simultaneously generate C-centred ester and N-centred iminyl radicals. This mild method features a remarkably broad substrate scope (up to 140 examples) and excellent tolerance of sensitive functional groups, and substrates that range from the simplest ethylene to complex (hetero)arenes can participate in the reaction, thus offering a general and practical access to β-amino acid derivatives.

Palladium-Catalyzed Regio- and Stereoselective Hydroaminocarbonylation of Unsymmetrical Internal Alkynes toward α,β-Unsaturated Amides

α,β-Unsaturated amides play a vital role in natural products, pharmaceuticals, organic synthesis, and functional materials. Herein, we disclosed a regio- and stereoselective hydroaminocarbonylation of unsymmetrical internal alkynes via palladium catalysis to synthesize α,β-unsaturated amides. This protocol features excellent regio- and exclusive (E)-stereoselectivity, high atom and step-economy, broad substrate scope, and functional group tolerance.

Palladium-Catalyzed Organic Reactions Involving Hypervalent Iodine Reagents

The chemistry of polyvalent iodine compounds has piqued the interest of researchers due to their role as important and flexible reagents in synthetic organic chemistry, resulting in a broad variety of useful organic molecules. These chemicals have potential uses in various functionalization procedures due to their non-toxic and environmentally friendly properties. As they are also strong electrophiles and potent oxidizing agents, the use of hypervalent iodine reagents in palladium-catalyzed transformations has received a lot of attention in recent years. Extensive research has been conducted on the subject of C—H bond functionalization by Pd catalysis with hypervalent iodine reagents as oxidants. Furthermore, the iodine(III) reagent is now often used as an arylating agent in Pd-catalyzed C—H arylation or Heck-type cross-coupling processes. In this article, the recent advances in palladium-catalyzed oxidative cross-coupling reactions employing hypervalent iodine reagents are reviewed in detail.

Palladium-Catalyzed Asymmetric Dearomative Carbonylation of Indoles

Herein, we disclose a strategy for the asymmetric dearomatization of N-arylacyl indoles via a palladium-catalyzed tandem Heck/carbonylation, leading to an array of indoline-3-carboxylates bearing vicinal C2-aza-quaternary and C3 tertiary stereocenters in high yields and excellent enantio- and diastereoselectivities. This study is an important advance in the field of asymmetric carbonylation and enantioselective dearomatization reactions.

Palladium-catalyzed intermolecular alkynylcarbonylation of unactivated alkenes: easy access to β-alkynylcarboxylic esters

A palladium-catalyzed intermolecular alkynylcarbonylation of unactivated alkenes has been established with ethynyl benziodoxolones (EBXs) as alkynylation reagents, providing β-alkynylcarboxylic esters efficiently from simple alkenes. The reaction features moderate to excellent regioselectivity and excellent functional group compatibility under mild reaction conditions.

Palladium-Catalyzed Intermolecular Carbonylation-Based Difunctionalization of Alkenes

The palladium(II)-catalyzed carbonylation of alkenes presents one of most efficient methods for the synthesis of alkyl-substituted carbonyls and has received much attention. In this Account, we summarize our recent studies on the palladium-catalyzed intermolecular carbonylation-based 1,2-difunctionalization of alkenes, in which two strategies were involved: (1) a cooperative strategy involves the sequential iodine(III)-mediated alkene activation and palladium-catalyzed carbonylation, leading to the intermolecular β-oxy-, fluoro-, and azidocarbonylation of alkenes; (2) the classic strategy initiated by intermolecular nucleopalladation and carbonylation, including the asymmetric oxycarbonylation of alkenes. These methods provide a series of efficient approaches to synthesize β-functionalized aliphatic carboxylic derivatives.

1 Introduction

2 A Cooperative Strategy Involving Iodine(III)-Mediated Alkene Activation and Palladium-Catalyzed Carbonylation

2.1 Intermolecular Oxycarbonylation of Alkenes

2.2 Intermolecular Fluorocarbonylation of Alkenes

2.3 Intermolecular Azidocarbonylation of Alkenes

3 Intermolecular Aminocarbonylation of Alkenes Initiated by Aminopalladation

4 Intermolecular Arylcarbonylation of Alkenes Initiated by Arylpalladation

5 Intermolecular Enantioselective Oxycarbonylation of Alkenes Initiated by Oxypalladation

6 Conclusion

On the Origin of Rh-Catalyzed Selective Ring-Opening Amidation of Substituted Cyclopropanols to Access β2-Amino Ketones

β²-Amino carbonyls, an α-substituted β-amino scaffold, hold a prominent place in the development of new pharmaceuticals and peptidomimetics. Herein, we report a highly efficient Rh-catalyzed ring-opening amidation of substituted cyclopropanols, which turned out to serve as a linchpin for the selective synthesis of β²-amino ketones to outcompete the formation of β³-isomers. Instead of the generally accepted rationale to consider steric factors for the β²-selectivity, orbital interaction was elucidated to play a more critical role in the amidative ring-opening of cyclopropanols to generate the key Rh-C intermediate. Subsequent inner-sphere acylnitrene transfer was achieved in excellent efficiency (TON > 5000) by using readily accessible dioxazolones as the amino source to afford β²-amino ketones with broad applicability.

Copper-Catalyzed 1,2-Trifluoromethylation Carbonylation of Unactivated Alkenes: Efficient Access to β-Trifluoromethylated Aliphatic Carboxylic Acid Derivatives

A novel copper-catalyzed carbonylative trifluoromethylation of unactivated alkenes has been developed. A broad range of β-trifluoromethylated carboxylic acid derivatives were prepared in moderate to excellent yields from simple alkenes with excellent regioselectivity. It is noteworthy that ethylene gas, as the simplest olefin, can also be applied directly to obtain β-trifluoromethylated amides and ester. This transformation presents the first example on carbonylative trifluoromethylation of alkenes.

Pd-Catalyzed and ligand-enabled alkene difunctionalization via unactivated C-H bond functionalization

Palladium-catalyzed and ligand-enabled C-H functionalization methods have emerged as a powerful approach for the preparation of therapeutically important motifs and complex natural products. Olefins, owing to their natural abundance, have been extensively employed for the formation of C-C and C-X bonds and the generation of various heterocycles. Traditionally, activated as well as starting materials with preinstalled functional groups, and also halide substrates under transition metal catalysis, have been employed for olefin difunctionalization. However, strategies for employing unactivated C-H bond functionalization to achieve alkene difunctionalization have rarely been explored. A possible solution to this challenge is the application of bulky ligands which enhances the reductive elimination pathway and inhibits β-hydride elimination to selectively yield difunctionalized alkene products. This feature article summarizes the utilization of unreactive C-H bonds in the Pd-catalyzed and ligand-enabled difunctionalization of alkenes.

A benzene-bridged divanadium complex-early transition metal catalyst for alkene alkylarylation with PhI(O2CR)2via decarboxylation

The synthesis, structure and catalytic activity of a benzene-bridged divanadium complex were comprehensively studied. The reduction of (Nacnac)VCl2 (1) (Nacnac = (2,6-iPr2C6H3NCMe)2HC) supported by β-diketiminate with potassium graphite (KC8) by employing benzene as the solvent allows access to the benzene-bridged inverted-sandwich divanadium complex (μ-η6:η6-C6H6)[V(Nacnac)]2 (2a), which can catalyze alkene alkylarylation with hypervalent iodine(iii) reagents (HIRs) via decarboxylation to generate regioselectively diverse indolinones. Furthermore, the mild nature of this reaction was amenable to a wide range of functionalities on alkenes and HIRs. Mechanistic studies revealed a relay sequence of decarboxylative radical alkylation/radical arylation/oxidative re-aromatization.

Three-component photoredox 1,2-alkylamination of styrenes with alkanes and nitrogen nucleophiles via C(sp3)–H bond cleavage

A three-component photoredox 1,2-alkylamination of styrenes involving functionalization of C(sp3)–H bonds in alkyl halides instead of functionalization of C-halogen bonds is disclosed.

Manganese-Catalyzed N-F Bond Activation for Hydroamination and Carboamination of Alkenes

A visible-light-promoted method for generating amidyl radicals from N-fluorosulfonamides via a manganese-catalyzed N-F bond activation strategy is reported. This protocol employs a simple manganese complex, Mn₂(CO)₁₀, as the precatalyst and a cheap silane, (MeO)₃SiH, as both the hydrogen-atom donor and the F-atom acceptor, enabling intramolecular/intermolecular hydroaminations of alkenes, two-component carboamination of alkenes, and even three-component carboamination of alkenes. A wide range of valuable aliphatic sulfonamides can be readily prepared using these practical reactions.

Hypervalent Iodine Reagents in Palladium-Catalyzed Oxidative Cross-Coupling Reactions

Hypervalent iodine compounds are valuable and versatile reagents in synthetic organic chemistry, generating a diverse array of useful organic molecules. Owing to their non-toxic and environmentally friendly features, these reagents find potential applications in various oxidative functionalization reactions. In recent years, the use of hypervalent iodine reagents in palladium-catalyzed transformations has been widely studied as they are strong electrophiles and powerful oxidizing agents. For instance, extensive work has been carried out in the field of C–H bond functionalization via Pd-catalysis using hypervalent iodine reagents as oxidants. In addition, nowadays, iodine(III) reagents have been frequently employed as arylating agents in Pd-catalyzed C–H arylation or Heck-type cross-coupling reactions. In this review, recent advancements in the area of palladium-catalyzed oxidative cross-coupling reactions using hypervalent iodine reagents are summarized in detail.

Constructing chiral bicyclo[3.2.1]octanes via palladium-catalyzed asymmetric tandem Heck/carbonylation desymmetrization of cyclopentenes

Transition-metal-catalyzed tandem Heck/carbonylation reaction has emerged as a powerful tool for the synthesis of structurally diverse carbonyl molecules, as well as natural products and pharmaceuticals. However, the asymmetric version was rarely reported, and remains a challenging topic. Herein, we describe a palladium-catalyzed asymmetric tandem Heck/carbonylation desymmetrization of cyclopentenes. Alcohols, phenols and amines are employed as versatile coupling reagents for the construction of multifunctional chiral bicyclo[3.2.1]octanes with one all-carbon quaternary and two tertiary carbon stereogenic centers in high diastereo- and enantioselectivities. This study represents an important progress in both the asymmetric tandem Heck/carbonylation reactions and enantioselective difunctionalization of internal alkenes.

Photosensitized Intermolecular Carboimination of Alkenes through the Persistent Radical Effect

An intermolecular, two-component vicinal carboimination of alkenes has been accomplished by energy transfer catalysis. Oxime esters of alkyl carboxylic acids were used as bifunctional reagents to generate both alkyl and iminyl radicals. Subsequently, addition of the alkyl radical to an alkene generates a transient radical for selective radical-radical cross-coupling with the persistent iminyl radical. Furthermore, this process provides direct access to aliphatic primary amines and α-amino acids by simple hydrolysis.

Intermolecular radical carboamination of alkenes

Vicinal alkene carboamination is a highly efficient and practical synthetic strategy for the straightforward preparation of diverse and valuable amine derivatives starting from simple compounds. During the last decade that approach has found continuous research interests and various practical methods have been developed using transition-metal catalysis. Driven by the renaissance of synthetic radical chemistry, intermolecular radical alkene carboamination comprising a C-C bond and a C-N bond forming step has been intensively investigated recently culminating in novel strategies and improved protocols which complement existing methodologies. Radical alkene carboamination can be achieved via three different reaction modes. Such cascades can proceed through N-radical addition to an alkene with subsequent C-C bond formation leading to 2,1-carboamination products. Alternatively, the C-C bond can be installed prior to the C-N bond via initial C-radical addition to the alkene with subsequent β-amination resulting in 1,2-carboamination. The third mode comprises initial single electron oxidation of the alkene to the corresponding alkene radical cation that gets trapped by an N-nucleophile and the cascade is terminated by radical C-C bond formation. In this review, the three different conceptual approaches will be discussed and examples from the recent literature will be presented. Further, the reader will get insights into the mechanism of the different transformations.

Rhenium-catalyzed alkylarylation of alkenes with PhI(O2CR)2via decarboxylation to access indolinones and dihydroquinolinones

Rhenium-catalyzed alkylarylation of alkenes with hypervalent iodine(iii) reagents (HIRs) via decarboxylation to access various 3,3-disubstituted indolinones and trans-3,4-dihydroquinolinones is described.

Substrate-controlled Diastereoselective Michael Addition of Alkylidene Malonates by Grignard Reagents

Herein is described a diastereoselective Michael addition of Grignard reagents to α, β- unsaturated diethyl malonates incorporated with a 2-oxazolidone chiral auxiliary. The catalyst-free Michael addition proceeds with good chemical efficiency and excellent stereoselectivity; and it provides new thoughts to the asymmetric synthesis of β-substituted β3 amino acid derivatives.

Organocatalytic Enantioselective Mukaiyama-Mannich Reaction of Isatin-Derived Ketimines for the Synthesis of Oxindolyl-β3, 3 -Amino Acid Esters

Mukaiyama-Mannich reactions of ester enolate equivalents with aldimines have been elegantly used for the asymmetric synthesis of β-amino acids; nevertheless, the corresponding asymmetric reaction employing ketimines are unexplored. Herein, the first organocatalytic enantioselective Mukaiyama-Mannich reaction employing isatin-derived ketimines with unsubstituted silyl ketene acetals is disclosed towards the scalable synthesis of 2-oxoindolinyl-β^3, 3 -amino acid esters at room temperature with excellent enantioselectivities (ee >99.5 %). Ultra-low catalyst loadings (as low as 250 ppm) could be used for the quantitative product formation with high enantiopurity. The synthetic utility of this protocol has been showcased in the short formal synthesis of pharmaceutically demanded (+)-AG-041R, a potent gastrin/CCK-B receptor antagonist.

Carboamination of Unactivated Alkenes through Three-Component Radical Conjugate Addition

Two-component Giese type radical additions are highly practical and established reactions. Herein, three-component radical conjugate additions of unactivated alkenes to Michael acceptors are reported. Amidyl radicals, oxidatively generated from α-amido oxy acids using redox catalysis, act as the third reaction component which add to the unactivated alkenes. The adduct radicals engage in Giese type additions to Michael acceptors to provide, after reduction, the three-component products in an overall alkene carboamination reaction. Transformations which can be conducted under practical mild conditions feature high functional group tolerance and broad substrate scope.

Photoredox-catalyzed oxo-amination of aryl cyclopropanes

Cyclopropanes represent a class of versatile building blocks in modern organic synthesis. While the release of ring strain offers a thermodynamic driving force, the control of selectivity for C–C bond cleavage and the subsequent regiochemistry of the functionalization remains difficult, especially for unactivated cyclopropanes. Here we report a photoredox-coupled ring-opening oxo-amination of electronically unbiased cyclopropanes, which enables the expedient construction of a host of structurally diverse β-amino ketone derivatives. Through one electron oxidation, the relatively inert aryl cyclopropanes are readily converted into reactive radical cation intermediates, which in turn participate in the ensuing ring-opening functionalizations. Based on mechanistic studies, the present oxo-amination is proposed to proceed through an S_N2-like nucleophilic attack/ring-opening manifold. This protocol features wide substrate scope, mild reaction conditions, and use of dioxygen as an oxidant both for catalyst regeneration and oxygen-incorporation. Moreover, a one-pot formal aminoacylation of olefins is described through a sequential cyclopropanation/oxo-amination.

The ring-opening and functionalization of electronically unbiased cyclopropanes is highly challenging to achieve in a regioselective fashion. Here, the authors report a mild photoredox-coupled oxoamination of electronically unactivated aryl cyclopropanes with simple azaarenes and molecular oxygen.