Visible-Light-Induced Nickel-Catalyzed Cross-Coupling with Alkylzirconocenes from Unactivated Alkenes
247 Pages Posted: 16 Apr 2019 Sneak Peek Status: Under ReviewMore...
Transition-metal-catalyzed cross-coupling reactions between naturally abundant sp3-hybridized carbon centers facilitate access to diverse molecules with complex three-dimensional structures. Organometallic compounds are among one of the most powerful reagents that broadly used in carbon–carbon bonds formations. Although sp2-hybridized organometallic compounds are widely used in cross-couplings, sp3-hybridized organometallic coupling partners are less developed. Herein, we report visible-light-induced single nickel-catalyzed C(sp3)–C(sp3), C(sp3)–C(sp2), and C(sp3)–C(sp) cross-coupling reactions using alkylzirconocenes, which are easily generated in situ from terminal or internal unactivated alkenes through hydrozirconation and chain walking. This method is mild and applicable for a large range of substrates including primary, secondary, tertiary alkyl, aryl, alkenyl, alkynyl halides and a variety of alkenes. Mechanistic studies suggest a novel nickel-catalyzed radical cross-coupling pathway, which represents the first visible-light-induced transformation of alkylzirconocenes.
Keywords: cross-coupling, photocatalysis, nickel precatalyst, alkylzirconocenes, unactivated alkenes, hydrozirconation, chain walk
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