Pd-Catalyzed Regioselective Si–C Bond Cleavage: Maximizing Chemo-Divergence in (4 + 2) Silacyclization Reactions of Alkynals

Precise control of catalyst systems to achieve chemodivergent synthesis from identical starting materials remains a fundamental challenge in catalysis and synthetic chemistry. Herein, we report a ligand-driven Pd-catalyzed regio- and chemodivergent (4 + 2) silacyclization reactions of benzosilacyclobutenes with unsymmetric alkynals, enabling the synthesis of all four dihydrobenzo­[c]­siline derivatives with remarkable selectivity. Each phosphine ligand uniquely dictates the reaction pathway, demonstrating unparalleled chemo-control and addressing long-standing challenges, including uncontrollable Si–C­(sp2) or Si–C­(sp3) bond cleavage and selective α-site or β-site addition to unsymmetrical alkynes. By leveraging steric and electronic properties of ligands, we achieve high yields and good selectivities, supported by mechanistic insights from DFT calculations. This strategy establishes a versatile platform for silacycle synthesis, with broad potential for atom-economics, chemistry, and materials science.