Nickel Catalyzed Vinylidene Insertions into O-H Bonds

Nickel-Catalyzed Cascade Reaction of 2-Vinylanilines with gem-Dichloroalkenes

An efficient nickel-catalyzed cascade reaction of 2-vinylanilines with gem-dichloroalkenes has been developed to deliver diversely substituted quinolines in good to high yields. This protocol enables effective access to quinolines bearing various functional groups in the cascade process from readily available feedstock chemicals. Mechanistic studies suggest that two plausible pathways are involved in the IPr-nickel catalytic system.

Catalytic Reductive Carbene Transfer Reactions

Efforts to develop catalytic carbene transfer reactions have largely relied on the use of diazo precursors. However, diazoalkanes are susceptible to undergoing violent exothermic decomposition unless they contain stabilizing substituents. Consequently, most synthetic methods are restricted to diazoacetates or related derivatives. In this Perspective, we describe an alternative approach to carbene transfer catalysis based on the generation of metal carbenoids from gem-dihaloalkanes and gem-dihaloalkenes. These precursors are readily available and stable in unsubstituted form or with a variety of donor and acceptor substituents. Using this approach, it is possible to design cyclopropanation reactions with non-stabilized carbenes, such as methylene, isopropylidene, and vinylidene. Furthermore, due to the distinct mechanistic pathways of these reactions, novel modes of cycloaddition can be carried out, including [4 + 1]-cycloadditions.

Diphosphino-Functionalized 1,8-Naphthyridines: a Multifaceted Ligand Platform for Boranes and Diboranes

A 1,8‐naphthyridine diphosphine (NDP) reacts with boron‐containing Lewis acids to generate complexes featuring a number of different naphthyridine bonding modes. When exposed to diborane B₂Br₄, NDP underwent self‐deprotonation to afford [NDP‐B₂Br₃]Br, an unsymmetrical diborane comprised of four fused rings. The reaction of two equivalents of monoborane BBr₃ and NDP in a non‐polar solvent provided the simple phosphine‐borane adduct [NDP(BBr₃)₂], which then underwent intramolecular halide abstraction to furnish the salt [NDP‐BBr₂][BBr₄], featuring a different coordination mode from that of [NDP‐B₂Br₃]Br. Direct deprotonation of NDP by KHMDS or PhCH₂K generates mono‐ and dipotassium reagents, respectively. The monopotassium reagent reacts with one or half an equivalent of B₂(NMe₂)₂Cl₂ to afford NDP‐based diboranes with three or four amino substituents.