Electronic Role of 3-Iminophosphine Ligands in Palladium-Catalyzed Intermolecular Hydroamination

Photocatalytic Generation of Aminium Radical Cations for C─N Bond Formation

Aminium radical cations have been extensively studied as electrophilic aminating species that readily participate in C─N bond forming processes with alkenes and arenes. However, their utility in synthesis has been limited, as their generation required unstable, reactive starting materials and harsh reaction conditions. Visible-light photoredox catalysis has emerged as a platform for the mild production of aminium radical cations from either unfunctionalized or N-functionalized amines. This Perspective covers recent synthetic methods that rely on the photocatalytic generation of aminium radical cations for C─N bond formation, specifically in the context of alkene hydroamination, arene C─H bond amination, and the mesolytic bond cleavage of alkoxyamines.

Catalysis and regioselectivity in hydrofunctionalization reactions of unsaturated carbon bonds. Part II. Hydroamination

This review continues consideration of the regioselectivity problem in the catalyzed hydrofunctionalization of unsaturated organic compounds and addresses hydroamination of unsaturated hydrocarbons. Particular parts of the review deal with reactions of alkenes, alkynes, allenes and dienes. It is shown that the selectivity of hydroamination depends on the natures of the reactants and the catalyst. Conditions of the reactions are described; in some cases, reaction mechanisms are discussed. Reactions for which divergent regioselectivity is possible are noted.

The bibliography includes 249 references.

Dedicated to the memory of V.V.Markovnikov.

Synthesis of α-CF3-substituted E-dehydroornithine derivatives via copper(i)-catalyzed hydroamination of allenes

Novel α-CF₃-substituted E-dehydroornithine derivatives have been synthesized via the Cu(i)-catalyzed hydroamination of α-CF₃-α-allenyl-α-aminocarboxylates/phosphonates with different amines.

Carbon Dioxide-Mediated C(sp3)-H Arylation of Amine Substrates

Elaborating amines via C-H functionalization has been an important area of research over the past decade but has generally relied on an added directing group or sterically hindered amine approach. Since free-amine-directed C(sp³)-H activation is still primarily limited to cyclization reactions and to improve the sustainability and reaction scope of amine-based C-H activation, we present a strategy using CO₂ in the form of dry ice that facilitates intermolecular C-H arylation. This methodology has been used to enable an operationally simple procedure whereby 1° and 2° aliphatic amines can be arylated selectively at their γ-C-H positions. In addition to potentially serving as a directing group, CO₂ has also been demonstrated to curtail the oxidation of sensitive amine substrates.

Selective hydrosilylation of N-allylimines using a (3-iminophosphine)palladium precatalyst

Hydrosilylation utilizing a (3-iminophosphine)palladium catalyst leads to the selective reduction of the imine unit of allylimines.

Anti-Markovnikov Hydroamination of Homoallylic Amines

The development of an anti-Markovnikov-selective hydroamination of unactivated alkenes is a significant challenge in organometallic chemistry. Herein, we present the rhodium-catalyzed anti-Markovnikov-selective hydroamination of homoallylic amines. The proximal Lewis basic amine serves to promote reactivity and enforce regioselectivity through the formation of the favored metallacycle, thus over-riding the inherent reactivity of the alkene. The scope of both the amine nucleophiles and homoallylic amines that participate in the reaction is demonstrated.