Palladium‐Catalyzed Hydrosilylation of Unactivated Alkenes and Conjugated Dienes with Tertiary Silanes Controlled by Hemilabile Hybrid P,O Ligand

Abstract

Novel P,O‐type ligands, N‐disulfonyl bicyclic bridgehead phosphorus triamides, were synthesized and utilized in Pd‐catalyzed hydrosilylation involving tertiary silanes, unactivated alkenes, and conjugated dienes. The ligand displayed a remarkable level of reactivity for alkene hydrosilylation with tertiary silanes and its use resulted in a significant improvement in the regioselectivity of diene hydrosilylation towards 1,2‐hydrosilylation. X‐ray crystallographic analysis confirmed the bidentate nature of the ligand, with coordination of phosphorus and oxygen. Control experiments provided evidence for the formation of Pd0 species and the reversibility of Pd−H insertion in the reaction mechanism. Density functional theory (DFT) computations supported the importance of the hemilabile P,O ligand in stabilizing both the rate‐determining transition state of Pd−H insertion and the transition state of reductive elimination that determines the regioselectivity.