Iron–Nickel Dual-Catalysis: A New Engine for Olefin Functionalization and the Formation of Quaternary Centers

Alkene hydroarylation forms carbon–carbon bonds between two foundational building blocks of organic chemistry: olefins and aromatic rings. In the absence of electronic bias or directing groups, only the Friedel–Crafts reaction allows arenes to engage alkenes with Markovnikov selectivity to generate quaternary carbons. However, the intermediacy of carbocations precludes the use of electron-deficient arenes, including Lewis basic heterocycles. Here we report a highly Markovnikov-selective, dual-catalytic olefin hydroarylation that tolerates arenes and heteroarenes of any electronic character. Hydrogen atom transfer controls the formation of branched products and arene halogenation specifies attachment points on the aromatic ring. Mono-, di-, tri-, and tetra-substituted alkenes yield Markovnikov products including quaternary carbons within nonstrained rings

Cobalt(III)-Catalyzed Directed C–H Allylation

The cobalt­(III)-catalyzed allylation was developed for amide-directed C–H activation of arenes, heteroarenes, and olefins. A variety of allyl sources can be employed to introduce this useful functional group

Direct C–H Arylation of Heteroarenes with Copper Impregnated on Magnetite as a Reusable Catalyst: Evidence for CuO Nanoparticle Catalysis in Solution

A reusable copper-based catalyst system was employed for the direct arylation of electron-rich heteroarenes. Under mild and operationally simple reaction conditions good yields and selectivities were obtained using diaryliodonium salts as coupling partners. A combination of experimental methods including kinetic studies, filtration tests, and a series of analytical tools (TXRF, ICP-MS, SEM, XPS, TEM, EFTEM) provide evidence for catalytically active soluble nanoparticles formed from an amorphous heterogeneous precursor. Mechanistic studies hint at a redox-neutral process which promotes counterion dissociation from the diaryliodonium salt by a copper­(II) oxide species

Co(III)-Catalyzed C–H Activation/Formal S_N‑Type Reactions: Selective and Efficient Cyanation, Halogenation, and Allylation

The first cobalt-catalyzed cyanation, halogenation, and allylation via C–H activation have been realized. These formal S_N-type reactions generate valuable (hetero)­aryl/​alkenyl nitriles, iodides, and bromides as well as allylated indoles using a bench-stable Co­(III) catalyst. High regio- and mono-selectivity were achieved for these reactions. Additionally, allylation proceeded efficiently with a turnover number of 2200 at room temperature, which is unprecedented for this Co­(III) catalyst. Alkenyl substrates and amides have been successfully utilized in Cp*Co­(III)-catalyzed C–H activation for the first time