Borane-Protecting Strategy for Hydrosilylation of Phosphorus-Containing Olefins

Abstract

Ir-catalyzed hydrosilylation of the alkenyl phosphine borane complex 1 was achieved to give the corresponding products 2. Because the phosphino group coordinates with metals and is unstable under aerobic conditions, the formation of the corresponding borane adduct was effective not only to promote the target hydrosilylation but also to keep 1 stable under aerobic conditions. The removal of coordinated borane from 2 was readily performed with the treatment by 1,4-diazabicyclo[2.2.2]octane to apply to further transformations. The immobilization and following deprotection of 2 on the surface of mesoporous silica were also examined.

Suzuki‐Miyaura Cross‐Coupling Reaction Using Palladium Catalysts Supported on Phosphine Periodic Mesoporous Organosilica

“…By following our new hydrosilylation methodology, [11h] reaction of diallylphosphine borane derivatives with (EtO) 3 SiH were performed in the presence of 2 mol% [IrCl(cod)] 2 (cod=1,5‐cyclooctadiene) to produce bis[3‐(triethoxysilyl)propyl]phenylphosphine borane ( 1 a ) and bis[3‐(triethoxysilyl)propyl]‐ tert ‐butylphosphine borane ( 1 b ) (Scheme 1, Figures S1‐6 in Supporting Information).…”

“…Driven by these backgrounds, we thus far conducted intensive study for the development of new hydrosilylation catalysts to synthesize various organosilicon compounds bearing various functionalities, which cannot be easily synthesized by conventional Pt hydrosilylation catalysts [11] . Through this study, we recently developed Ir‐catalyst system to perform hydrosilylation of phosphorus‐containing compounds to easily produce bifunctional compounds with alkoxy silyl and phosphino groups [11h] . With this new methodology in hands, we herein embarked on the development of PMOs with phosphorus‐coordinating moieties, phosphine‐PMOs (R‐P‐PMO‐TMS: R=Ph, t Bu), which bear trialkyl phosphine moieties as an electron‐donating coordination sites.…”