Cobalt-catalyzed carbon-carbon bond formation via radicals

Cobalt‐Catalyzed Coupling of Alkyl Iodides with Alkenes: Deprotonation of Hydridocobalt Enables Turnover

“…We note that substrates including nitroarenes, α‐bromo‐ and α‐chloro esters are unsuitable for the reaction, as the starting material remained unreacted. Additionally, mixtures of isomeric olefin products are observed when there are multiple β‐H elimination pathways for the intermediate organocobalt species, as previously noted by Giese et al12b…”

Cobalt‐Catalyzed Coupling of Alkyl Iodides with Alkenes: Deprotonation of Hydridocobalt Enables Turnover

“…[10] In synthetic applications employing stoichiometric organocobalt reagents the reactive intermediates most typically undergo addition to an olefin to give a new organocobalt species. [12] Careful analysis of these methods reveals potential complications with respect to functional group compatibility (e.g. The latter subsequently decompose to H 2 and ill-defined Co II complexes (step v).…”

“…This has been most notably effected under reductive conditions, namely electrolytically, by Zn or by the stoichiometric use of Grignard reagents. [12] Careful analysis of these methods reveals potential complications with respect to functional group compatibility (e.g. aldehydes and ketones); indeed, it has been noted that enoates are unsuitable substrates in such Heck-type couplings.…”

Radical Cyclization of Haloacetals: The Ueno-Stork Reaction

“…Other catalysts for similar cobalt-mediated reductive cyclizations have been developed. [103][104][105] For instance, cobaloxime, 100,106-108 modified cobaloxime 109 and salophen 107 derivatives have been applied with success to haloacetal cyclizations. A typical example is shown in Scheme 28.…”