Catalytic Asymmetric Construction of Si‐Chiral Silabicyclo[3.3.1]Nonanes Using Functionalized Prochiral Silacyclohexanones

ABSTRACT The development of chiral three‐dimensional, sp 3 ‐rich architectures to facilitate the discovery of potent functional molecules is at the forefront of synthetic chemistry. However, facile synthesis of saturated and bridged Si‐chiral silacycles remains elusive due to a lack of pluripotent Si‐prochiral platforms capable of diversity‐oriented asymmetric synthesis. Herein, we report the invention of functionalized prochiral 4,4‐disubstituted silacyclohexanones (FPDSs) as platforms for the modular synthesis of multifunctional sp 3 ‐rich Si‐chiral sila‐bicyclo[3.3.1]nonanes. The FPDS platforms are readily accessible via a newly established tandem S N 2‑substitution/Krapcho‑decarboxylation sequence as a key step to silacyclohexanone core. The utility of FPDS is demonstrated in catalytic asymmetric synthesis of diverse Si‐chiral sila‐bicyclo[3.3.1]nonanes via desymmetric intramolecular aldol reaction, tandem imine formation/Mannich, or Wittig/Michael sequence by chiral enamine catalysis, as well as α‐arylation by cooperative chiral enamine/palladium catalysis. Notably, this represents the first stereoselective method to produce functionalized sp 3 ‐rich Si‐chiral bridged silacycles and the first asymmetric organo/metal cooperative catalysis for forging Si‐chirality.