Branch-Selective Hydroarylation: Iodoarene–Olefin Cross-Coupling

Abstract

A combination of cobalt and nickel catalytic cycles enables a highly branch-selective (Markovnikov) olefin hydroarylation. Radical cyclization and ring scission experiments are consistent with hydrogen atom transfer (HAT) generation of a carbon-centered radical that leads to engagement of a nickel cycle.

Ni-catalyzed deaminative cross-electrophile coupling of Katritzky salts with halides via C─N bond activation

“…However, forging sp 3 -hybridized carbon centers remains a great challenge mainly due to the weak nucleophilic reactivity of sp 3 carbon centers and their innate difficulties in coordination with metals (4)(5)(6)(7). In recent years, various alkyl radical precursors including halides (4,(8)(9)(10)(11), silicones (12), dihydropyridine (13), carboxylic acids (14)(15)(16), sulfones (17), and others (18)(19)(20) have been used for radical cross-coupling reactions (Fig. 1A).…”

Cobalt bis(acetylacetonate)–tert-butyl hydroperoxide–triethylsilane: a general reagent combination for the Markovnikov-selective hydrofunctionalization of alkenes by hydrogen atom transfer

“…Additionally, methods to achieve carbon–carbon bond formation to alkenes by HAT have been developed (e.g., reductive coupling [22–28], formal hydromethylation [29], cycloisomerization [8,30–31], hydrooximation [32], hydroheteroarylation [28,33–35], hydroarylation [36–38], and cross-coupling [37]). Many of these transformations have found applications in synthesis [6,39–47].…”

“…To the best of our knowledge, the iron oxalate–sodium borohydride system, introduced by Boger and co-workers [8], is the only reagent combination shown to accommodate a broad range of SOMOphiles. However, the cobalt–salen complexes that are commonly employed [10–11 13,15–16 30–32 36–37 48] contain many different ligand architectures [21], and often need to be prepared by multistep sequences. Here we report a uniform set of reaction conditions to achieve a broad range of HAT hydrofunctionalization reactions using the simple reagents cobalt acetoacetonate [Co(acac) 2 ], tert -butyl hydroperoxide (TBHP), and triethylsilane (Et 3 SiH).…”

Cyclopropanation of Terminal Alkenes through Sequential Atom‐Transfer Radical Addition/1,3‐Elimination

“…[50][51][52] Chen and co-workers have reported Pd 0 -catalyzed cyclopropanation of norbornene using potassium iodomethyltrifluoroborate. [43,44,46,[57][58][59][60][61] and to ate complexes of vinylboronates. Radical stabilization energies (RSEs) of 1-borylated radicals and resonanceh ybrids of boronic esters derived radicals.…”