Divergent Synthesis of Silacycles by Ligand-Controlled Rhodium-Catalyzed Annulation of (2-Hydrosilylaryl)acetylenes

This study demonstrates the rhodium-catalyzed divergent synthesis of 5-, 5,6-, and 8-membered silacyclic compounds, such as benzosilole, silolosiline, and disilocine, from (2-hydrosilylaryl)acetylenes. To achieve high product selectivity, intra- and intermolecular reactions are controlled by tuning the mono- and bidentate phosphine ligands on the rhodium catalyst precursor. Deuterium labeling experiments and computational studies reveal that the annulation reaction proceeds via hydride transfer to the alkyne moiety.