Fe-Catalyzed C–C Bond Construction from Olefins via Radicals

Abstract

This Article details the development of the iron-catalyzed conversion of olefins to radicals and their subsequent use in the construction of C–C bonds. Optimization of a reductive diene cyclization led to the development of an intermolecular cross-coupling of electronically-differentiated donor and acceptor olefins. Although the substitution on the donor olefins was initially limited to alkyl and aryl groups, additional efforts culminated in the expansion of the scope of the substitution to various heteroatom-based functionalities, providing a unified olefin reactivity. A vinyl sulfone acceptor olefin was developed, which allowed for the efficient synthesis of sulfone adducts that could be used as branch points for further diversification. Moreover, this reactivity was extended into an olefin-based Minisci reaction to functionalize heterocyclic scaffolds. Finally, mechanistic studies resulted in a more thorough understanding of the reaction, giving rise to the development of a more efficient second-generation set of olefin cross-coupling conditions.

Late-Stage C–H Alkylation of Heterocycles and 1,4-Quinones via Oxidative Homolysis of 1,4-Dihydropyridines

“…Interestingly, the regioselectivity is orthogonal to that observed for the Friedel-Crafts reaction, thus increasing the appeal of such transformations. Traditionally, carboxylic acids 5 and halides 6 have been employed as radical precursors, but more recently the toolbox has been expanded to include alcohols, 7 boronic acids, 8 sulfinate salts, 9 alkenes, 10 and alkyltrifluoroborates. 11 However, in most of the previous contributions, high temperatures, (sub)stoichiometric amounts of expensive metal salts, an excess of the radical precursor, and strong oxidants or expensive photocatalysts 7,11a,12 are required to achieve good yields.…”

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].…”

Neue Entwicklungen auf dem Gebiet der Minisci‐Reaktion

“…[155] In diesem Verfahren war eine Aktivierung durch Brønsted-Säure nicht erfolgreich. [155] In diesem Verfahren war eine Aktivierung durch Brønsted-Säure nicht erfolgreich.…”