報告題目：Stereoselective Alkene Carbofunctionalization via Radical and Two-Electron Pathways

報告人：刁天甯（Tianning Diao），New York University

主持人：裴堅

時間：2019年7月18日上午，10:00−11:30

地點：化學學院B229

講座摘要：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.