2025/07/29 by Zuo, Honghua, Kemper, Sebastian, Klare, Hendrik F. T. +1
#500 Naturwissenschaften und Mathematik::540 Chemie::540 Chemie und zugeordnete Wissenschaften #allenylation #hydrosilylation #silylium-ion catalysis #vinyl cation intermediates #α‑C–H functionalization
paper · doi:10.14279/depositonce-23027
A silylium-ion-promoted α-C–H allenylation of silyl ethers tethered to an internal alkyne is described. The actual intermolecular allenylation event occurs after the trans -selective hydrosilylation of the alkyne, where an in situ-generated β-silicon-stabilized vinyl cation engages in an intramolecular [1,5]-hydride shift. This process transforms the silyl ether into a silylcarboxonium ion, which reacts with propargylsilanes as nucleophiles, formed by the rapid silylium-ion-catalyzed isomerization of allenylsilanes. As part of the allenylation step, the propagating silylium-ion electrophile is regenerated, thereby closing the catalytic cycle. An allylsilane is also applicable in this transformation, producing the corresponding α-C–H allylation product in high yield.