Access to Chiral (Semi)Saturated Silacycles via Rh-Catalyzed Asymmetric Sila-(3+2) Annulation

Abstract Five-membered (hetero)cycles are ubiquitous privileged scaffolds, yet their silicon analogs remain synthetically elusive, especially those bearing multiple carbon and silicon stereocenters. Here, we report a rhodium-catalyzed enantioselective sila-(3+2) annulation that directly addresses this gap. This reaction is driven by a unique 1,2-silyl migration, enabling the modular union of alkynylsilanes and alkenes as complementary C2Si and C2 synthons. This process provides efficient, one-step access to a wide range of functionalized chiral silacyclopent-2-enes (>40 examples) with excellent stereocontrol (up to >99% e.e., >20:1 d.r.), including complex bioactive molecule derivatives. The products serve as versatile linchpins for diversification, enabling streamlined synthesis of polysubstituted silacyclopentanes bearing multiple C- and Si-stereogenic centers. This work establishes a general and practical platform for accessing a vast, unexplored chemical space of chiral (semi)saturated silacycles, with broad implications for drug discovery and beyond.