NiH-catalyzed C-N bond formation: insights and advancements in hydroamination of unsaturated hydrocarbons.

The formation of C-N bonds is a fundamental aspect of organic synthesis, and hydroamination has emerged as a pivotal strategy for the synthesis of essential amine derivatives. In recent years, there has been a surge of interest in metal hydride-catalyzed hydroamination reactions of common alkenes and alkynes. This method avoids the need for stoichiometric organometallic reagents and overcomes problems associated with specific organometallic compounds that may impact functional group compatibility. Notably, recent developments have brought to the forefront olefinic hydroamination and hydroamidation reactions facilitated by nickel hydride (NiH) catalysis. The inclusion of suitable chiral ligands has paved the way for the realization of asymmetric hydroamination reactions in the realm of olefins. This review aims to provide an in-depth exploration of the latest achievements in C-N bond formation through intermolecular hydroamination catalyzed by nickel hydrides. Leveraging this innovative approach, a diverse range of alkene and alkyne substrates can be efficiently transformed into value-added compounds enriched with C-N bonds. The intricacies of C-N bond formation are succinctly elucidated, offering a concise overview of the underlying reaction mechanisms. It is our aspiration that this comprehensive review will stimulate further progress in NiH-catalytic techniques, fine-tune reaction systems, drive innovation in catalyst design, and foster a deeper understanding of the underlying mechanisms.

Nickel-Catalyzed Kinetic Resolution of Racemic Unactivated Alkenes via Enantio-, Diastereo-, and Regioselective Hydroamination.

Kinetic resolution is a powerful strategy for the isolation of enantioenriched compounds from racemic mixtures, and the development of selective catalytic processes is an active area of research. Here, we present a nickel-catalyzed kinetic resolution of racemic α-substituted unconjugated carbonyl alkenes via the enantio-, diastereo-, and regioselective hydroamination. This protocol affords both chiral α-substituted butenamides and syn-ß2,3 -amino acid derivatives with high enantiomeric purity (up to 99 % ee) and selectivity factor up to >684. The key to the excellent kinetic resolution efficiency is the distinctive architecture of the chiral nickel complex, which enables successful resolution and enantioselective C-N bond construction. Mechanistic investigations reveal that the unique structure of the chiral ligand facilitates a rapid migratory insertion step with one enantiomer. This strategy provides a practical and versatile approach to prepare a wide range of chiral compounds.

Nickel-Catalyzed Regio- and Enantioselective Hydroamination of Unactivated Alkenes Using Carbonyl Directing Groups.

The asymmetric addition of an N-H bond to various alkenes via a direct catalytic method is a powerful way of synthesizing value-added chiral amines. Therefore, the enantio- and regioselective hydroamination of unactivated alkenes remains an appealing goal. Here, we report the highly enantio- and regioselective Ni-catalyzed hydroamination of readily available unactivated alkenes bearing weakly coordinating native amides or esters. This method succeeds for both terminal and internal unactivated alkenes and has a broad amine coupling partner scope. The mild reaction process is well suited for the late-stage functionalization of complex molecules and has the potential to gain modular access to enantioenriched ß- or γ-amino acid derivatives and 1,2- or 1,3-diamines. Mechanistic studies reveal that a chiral bisoxazoline-bound Ni specie effectively leverages carbonyl coordination to achieve enantio- and regioselective NiH insertion into alkenes.

Imidazole-Selective Alkyne Hydroamination under Physiological Conditions.

Imidazole-selective intermolecular hydroamination reaction has been discovered. This unprecedented additive-free addition reaction proceeds in an exclusively regioselective and stereoselective manner with high atom economy under extremely mild reaction conditions.