白小姐·2019年先锋诗» 学术讲座» Stereoselective Alkene Carbofunctionalization via Radical and Two-Electron Pathways

Stereoselective Alkene Carbofunctionalization via Radical and Two-Electron Pathways

报告题目:Stereoselective Alkene Carbofunctionalization via Radical and Two-Electron Pathways

报告人:刁天宁(Tianning Diao),New York University

主持人:裴坚

时间:2019718日上午,10:00−11:30

地点:化学学院B229

 

讲座摘要:Nickel catalysts exhibit unique properties. Open-shell configurations are relatively stable and readily accessible, which lead radical pathways. Moreover, the reduction potential of Ni is considerably lower than that of Pd. This reactivity is employed to functionalize alkenes. Enantioselective 1,2-dicarbofunctionalization of alkenes accesses molecules with intricate substitution patterns while introducing stereocenters. This method is readily applicable to prepare molecules with important bioactivity, such as a,a,b-triarylated ethane scaffolds. The use of reducing conditions with alkyl and aryl halides as the coupling partners avoids stoichiometric organometallic reagents and tolerates a broad range of functional groups. Mechanistic studies reveal that the use of Ni catalysts initiates radical formation and leads to unconventional enantio-determining steps. A two-electron redox pathway on a Ni(I)/Ni(III) platform achieves trans-selective diene coupling to afford important cyclic structures.

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