Palladium-Catalyzed (4 + 4) Annulation of Silacyclobutanes and 2‑Iodobiarenes to Eight-Membered Silacycles via C–H and C–Si Bond Activation

Construction of eight-membered silacycles via Pd-catalyzed (4 + 4) annulation of silacyclobutanes and 2-iodobiphenyl derivatives is described. This strategy involves direct C–H and C–Si bond activation followed by a ring annulation and features low catalyst loading, ligand-free conditions, and readily available starting materials. Mechanistic studies revealed the involvement of five-membered palladacycle species in the reaction.本文报道了通过钯（Pd）催化硅杂环丁烷（silacyclobutanes）与2-碘联苯衍生物的(4+4)环化反应构建八元硅杂环（eight-membered silacycles）的方法。该策略依次经历直接C-H键与C-Si键活化及环化环合过程，具有催化剂负载量低、无配体反应条件、起始原料易得等特点。机理研究揭示，该反应过程中涉及五元钯杂环（five-membered palladacycle）物种。