Cobalt-Catalyzed C-C and C-N Coupling reactions

Abstract : This thesis allowed realizing new cobalt-catalyzed cross-coupling reactions. The first chapter describes a new route for the direct allylation of various alkyl halides catalyzed by cobalt(II) bromide. This method is very straightforward and environmentally friendly. It is efficient for the coupling of a large variety of alkyl halides (primary, secondary, and tertiary) with substituted (primary and secondary) allylic acetates and carbonates and provides good to excellent yields with good functional group tolerance. Moreover, in the case of substituted allyl acetates, the reaction affords the linear product as the major or the sole product. A few experiments were also conducted to provide some insight into the mechanism of this allyl-alkyl cross coupling reaction. This methodology is also extended to explore the cobalt-catalyzed reductive alkyl-alkyl/allyl-allyl coupling reactions. The second chapter reports a highly efficient method for the amination of functionalized arylzinc reagents with N-chloroamines from primary (including benzyl amines) or secondary amines. The high catalytic efficiency of the versatile cobalt catalyst made the procedure remarkably simple and general. Compared to other electrophilic amination pathways, this method reported requires milder conditions, is cost-effective, presents a wide substrate scope (both primary and secondary amines can react freely with arylzinc compounds bearing a para, meta or ortho position substituted group), and especially a good tolerance to a large number of important sensitive functional groups. According to these progresses, some initial study on the construction of C-S bond using arylzinc species and electrophilic sulfur source is also presented. In the third chapter we found that the arylzinc compounds obtained via cobalt catalysis, react with a greener cyanide resource N-cyano-N-phenyl-p-methyl-benzenesulfonamide (NCTS), and provide the corresponding aryl nitriles under mild conditions in good to excellent yields. We also investigate the reactivity of analoguous cyanide resources.
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Xin Qian. Cobalt-Catalyzed C-C and C-N Coupling reactions. Organic chemistry. Ecole Polytechnique X, 2013. English. ⟨pastel-00943479⟩

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