Migratory Reductive Cross-Coupling via Dual Nickel Metathesis

Cross-electrophile coupling has been developed into a practical approach for the construction of carbon-carbon bonds, wherein nickel catalysis has been widely employed. Mechanistically, a catalytic cycle involvingsequentially selective oxidative addition or radical chain process is proposed. Although the catalytic cycle of dual nickel metathesis has been discussed in several important works, none thinks this pathway is possible. In this manuscript, we present a thorough mechanistic study by a series of designed experiments toward the nickel-catalyzed migratory reductive cross-coupling. The results suggest that a catalytic cycle involving two organonickel(II) species metathesis as a key step, operates in this reaction. Moreover, we provide a discussion on the difference between the nickel-catalyzed migratory reductive cross-couplings and the classical ones. Additionally, based on the mechanistic finding, a new catalytic system has also been developed, which allows the use of electron-deficient aryl halides as starting materials, affording the migratory cross-coupling products efficiently.</div

Ligand-modulated nickel-catalyzed regioselective silylalkylation of alkenes

Abstract Organosilicon compounds have shown tremendous potential in drug discovery and their synthesis stimulates wide interest. Multicomponent cross-coupling of alkenes with silicon reagents is used to yield complex silicon-containing compounds from readily accessible feedstock chemicals but the reaction with simple alkenes remains challenging. Here, we report a regioselective silylalkylation of simple alkenes, which is enabled by using a stable Ni(II) salt and an inexpensive trans−1,2-diaminocyclohexane ligand as a catalyst. Remarkably, this reaction can tolerate a broad range of olefins bearing various functional groups, including alcohol, ester, amides and ethers, thus it allows for the efficient and selective assembly of a diverse range of bifunctional organosilicon building blocks from terminal alkenes, alkyl halides and the Suginome reagent. Moreover, an expedient synthetic route toward alpha-Lipoic acid has been developed by this methodology

Photochemical Nickel-Catalyzed Reductive Migratory Cross-Coupling of Alkyl Bromides with Aryl Bromides

A novel method to access 1,1-diarylalkanes from readily available, nonactivated alkyl bromides and aryl bromides via visible-light-driven nickel and iridium dual catalysis, wherein diisopropylamine (^<i>i</i>Pr₂NH) is used as the terminal stoichiometric reductant, is reported. Both primary and secondary alkyl bromides can be successfully transformed into the migratory benzylic arylation products with good selectivity. Additionally, this method showcases tolerance toward a wide array of functional groups and the presence of bases

Ligand-Controlled Nickel-Catalyzed Reductive Relay Cross-Coupling of Alkyl Bromides and Aryl Bromides

1,1-Diarylalkanes are important structural frameworks which are widespread in biologically active molecules. Herein, we report a reductive relay cross-coupling of alkyl bromides with aryl bromides by nickel catalysis with a simple nitrogen-containing ligand. This method selectively affords 1,1-diarylalkane derivatives with good to excellent yields and regioselectivity

Synthesis of Secondary Unsaturated Lactams via an Aza-Heck Reaction

The preparation of unsaturated secondary lactams via the palladium-catalyzed cyclization of <i>O</i>-phenyl hydroxamates onto a pendent alkene is reported. This method provides rapid access to a broad range of lactams that are widely useful building blocks in alkaloid synthesis. Mechanistic studies support an aza-Heck-type pathway