Directed Asymmetric Nickel-Catalyzed Reductive 1,2-Diarylation of Electronically Unactivated Alkenes

Regioselective 1,2-Di(hetero)arylation of Activated and Unactivated Alkenes with (Hetero)aryl Chlorides

Aryl chlorides are more commercially available and lower cost compared with aryl bromides and iodides. However, the use of (hetero)aryl chlorides as aryl radical precursors for the di(hetero)arylation of alkenes remains an underdeveloped area. Furthermore, existing examples of theses reactions are predominantly confined to activated alkenes. In this study, we introduce a photoirradiation-promoted benzophenone-catalyzed 1,2-di(hetero)arylation process that is applicable to both activated and unactivated alkenes, utilizing (hetero)aryl chlorides and cyanoarenes as aryl sources. Importantly, this method allows for the simultaneous introduction of two heterocycles to alkenes with high regioselectivity.

Regioselective Synthesis of β,γ-Unsaturated Amides from Unactivated Alkenes

β,γ-Unsaturated amides are valuable substrates for downstream functionalization reactions but can be challenging to prepare. Herein, we introduce an approach featuring the regioselective addition of carbamoyl chlorides to unactivated alkenes, present its scope and limitations, and exemplify its synthetic utility.

Ni-catalyzed regioselective and site-divergent reductive arylalkylations of allylic amines

Catalytic methods by switching the least parameters for regioselective and site-divergent transformations to construct different architectures from identical and readily available starting materials are among the most ideal catalytic protocols. However, the associated challenge to precisely control both regioselectivity and site diversity renders this strategy appealing yet challenging. Herein, Ni-catalyzed cross-electrophile regioselective and site-divergent 1,2- and 1,3-arylalkylations of N-acyl allylic amines have been developed. This Ni-catalyzed reductive three-component protocol enables 1,2-arylalkylation and 1,3-arylalkylation of allylic amines with aryl halides and alkyl halides with excellent chemo-, regio- and site-selectivity, representing the first example of controlled migratory difunctionalization of alkenes under reductive conditions. A wide range of terminal and internal unactivated allylic amines, aryl halides and alkyl precursors were tolerated, providing straightforward and efficient access to diverse C(sp3)-rich branched aliphatic amines from identical starting materials.

Ni-Catalyzed Regioselective Alkylarylation of Unactivated Alkenes in Amines Enabled by Cooperative Ligand Effects of Nitriles and Electron-Deficient Alkenes

We report a Ni-catalyzed vicinal alkylarylation of unactivated alkenes in γ,δ- and δ,ε-alkenylamines with aryl halides and alkylzinc reagents. The reaction is enabled by amine coordination and can use all primary, secondary, and tertiary amines. The reaction constructs two new C(sp3)-C(sp3) and C(sp3)-C(sp2) bonds and produces δ- and ε-arylamines with C(sp3)-branching at the γ- and δ-positions. A variety of aryl and heteroaryl iodides and both the primary and secondary alkylzinc reagents can be used as coupling carbon sources. Mechanistic studies suggest that the reaction is enabled by the cooperative effect of organic nitriles and electron-deficient alkenes (EDAs) as ligands.

Cross-Electrophile Coupling: Principles, Methods, and Applications in Synthesis

Cross-electrophile coupling (XEC), defined by us as the cross-coupling of two different σ-electrophiles that is driven by catalyst reduction, has seen rapid progression in recent years. As such, this review aims to summarize the field from its beginnings up until mid-2023 and to provide comprehensive coverage on synthetic methods and current state of mechanistic understanding. Chapters are split by type of bond formed, which include C(sp3)-C(sp3), C(sp2)-C(sp2), C(sp2)-C(sp3), and C(sp2)-C(sp) bond formation. Additional chapters include alkene difunctionalization, alkyne difunctionalization, and formation of carbon-heteroatom bonds. Each chapter is generally organized with an initial summary of mechanisms followed by detailed figures and notes on methodological developments and ending with application notes in synthesis. While XEC is becoming an increasingly utilized approach in synthesis, its early stage of development means that optimal catalysts, ligands, additives, and reductants are still in flux. This review has collected data on these and various other aspects of the reactions to capture the state of the field. Finally, the data collected on the papers in this review is offered as Supporting Information for readers.

Ligand-enabled Ni-catalysed dicarbofunctionalisation of alkenes with diverse native functional groups

The transition metal-catalysed dicarbofunctionalisation of unactivated alkenes normally requires exogenous strong coordinated directing groups, thus reducing the overall reaction efficiency. Here, we report a ligand-enabled Ni(II)-catalysed dicarbofunctionalisation of unactivated alkenes with aryl/alkenyl boronic acids and alkyl halides as the coupling partners with a diverse range of native functional groups as the directing group. This dicarbofunctionalisation protocol provides an efficient and direct route towards vicinal 1,2-disubstituted alkanes using primary, secondary, tertiary amides, sulfonamides, as well as secondary and tertiary amines under redox-neutral conditions that are challenging to access through conventional methods. The key to the success of this reaction is the use of a bulky β-diketone ligand, which could enable the insertion of alkene to aryl-Ni(II) species, stabilize the alkyl-Ni(II) species and inhibit the homolytic alkyl-Ni(II) cleavage, supporting by both experimental and computational studies. This dicarbofunctionalisation reaction features the use of native directing group, a broad substrate scope, and excellent scalability.

Iron-Mediated Dialkylation of Alkenylarenes with Benzyl Bromides

We disclose a method for the dibenzylation of alkenylarenes with benzyl bromides using iron powder. This reaction generates branched alkyl scaffolds adorned with functionalized aryl rings through the formation of two new C(sp3)-C(sp3) bonds at the vicinal carbons of alkenes. This protocol tolerates electron-rich, electron-neutral, and electron-poor benzyl bromides and alkenylarenes. Mechanistic studies suggest the formation of benzylic radical intermediates as a result of single-electron transfer from the iron, which is intercepted by alkenylarenes.

Synthesis of Diarylalkanes by Photoreductive 1,2-Diarylation of Alkenes with Aryl Halides and Cyanoaromatics

We report a visible light-induced photoreductive strategy for three-component diarylation of alkenes with aryl halides and cyanoaromatics. Upon photoredox catalysis and with tertiary alkyl amines as the electron transfer agent, aryl halides selectively undergo halogen atom transfer to generate the aryl radicals and two C(sp2)-C(sp3) bonds between the cabron atoms are created in a radical addition and radical-radical coupling fashion to rapidly assemble diverse functionalized polyarylalkanes with high regio- and chemoselectivity. This method can be applied to broad feedstocks, including terminal alkenes, internal alkenes, aryl iodides, aryl bromides, aryl chlorides, electron-deficient benzonitriles, and isonicotinonitriles.

Enantioselective Aminosilylation of Alkenes by Palladium/Ming-Phos-Catalyzed Tandem Narasaka-Heck/Silylation Reaction

A Pd-catalyzed enantioselective aminosilylation of alkenes via tandem Aza-Heck/silylation reaction under Pd/Sadphos catalysis is disclosed. A wide array of oxime esters and silicon reagents are tolerated, furnishing the chiral pyrrolines bearing one quaternary or two contiguous stereocenters in good yield with high enantioselectivity. Not only terminal alkenes but also tri-substituented internal alkenes successfully participate in the reaction, delivering vicinal stereocenters in complete diastereoselectivity and high enantioselectivity. DFT study is conducted to probe the reaction pathway and the origin of the enantioselectivity, which revealed that the stereoinduction arises from the weak interaction between the aromatic ring of the substrate fragment and naphthyl group in the ligand.

Ni-Catalyzed Linearizable Cyclization/Coupling with Detachable Silicon-Oxygen Linker: Access to 1,2-Oxasilolanes, 3-Hydroxysilanes and 4-Arylalkanols

We disclose a Ni-catalyzed cyclization/alkylmetal interception reaction in which products are readily linearized to permit regiodefined alkene dicarbofunctionalization. This method offers a convenient route to access 1,2-oxasilolane heterocycles, 3-hydroxysilanes and 4-arylalkanols with the formation of C(sp3)-C(sp3) bonds at primary and secondary alkyl carbon centers. In this reaction, a silicon-oxygen (Si-O) bond functions as a detachable linker that can be delinked with several hydride, alkyl, aryl and vinyl nucleophiles to create profusely functionalized 3-hydroxysilanes. A silicon motif in the cyclic C(sp3)-Si-O construct in 1,2-oxasilolane heterocycles can also be selectively deleted by Pd-catalyzed hydrodesilylation affording Si-ablated linear alcohol products reminiscent of vicinal ethylene dicarbofunctionalization with C(sp3) and C(sp2) carbon sources.

Iodonium based regioselective double nucleophilic alkene functionalization of a hydrofluoroolefin scaffold

Herein, we report a modular regioselective alkene difunctionalization strategy based on the use of hydrofluoroolefin (HFO) gas as fluorous feedstock material. The transformation of the HFO gas to iodonium salt creates vicinal electrophilic sites readily available for a broad range of nucleophiles.

Nickel-Catalyzed 8-Aminoquinoline Directed Reductive Dialkylcyclization/Homodialkylation of Unactivated Alkenes

Chemo and regioselective dialkylation of alkene is an efficient protocol for constructing useful chemicals, but challenges remain in the unrestricted application of alkylating reagents. Alkyl bromide belongs to the easy-to-access and operable alkyl electrophiles that can be used in reductive coupling with alkenes. Here, we reported convenient strategies for dialkylcyclization and homodialkylation of unactivated β,γ- and γ,δ-unsaturated alkenyl amides with 1,3-dibromoalkanes or primary alkyl bromides under nickel-catalyzed reductive conditions that exhibited high regioselectivity and functional-group tolerance.

Nickel-Catalyzed Regioselective Intermolecular Dialkylation of Alkenylarenes: Generation of Two Vicinal C(sp3 )-C(sp3 ) Bonds Across Alkenes

We disclose a Ni-catalyzed regioselective dialkylation reaction of alkenylarenes with α-halocarbonyls and alkylzinc reagents. The reaction produces γ-arylated alkanecarbonyl compounds with the generation of two new C(sp3 )-C(sp3 ) bonds at the vicinal carbons of alkenes. This reaction is effective for the use of primary, secondary and tertiary α-halocarboxylic esters, amides and ketones in conjunction with primary and secondary alkylzinc reagents as the sources of two C(sp3 ) carbons for the dialkylation of terminal and cyclic internal alkenes.