Unique Reactivity of Dihydrosilanes under Catalysis by Supported Gold Nanoparticles: cis‐1,2‐Dehydrogenative Disilylation of Alkynes

Abstract

In contrast to monohydrosilanes (R3SiH), which in the presence of supported gold nanoparticles primarily undergo typical β‐(E)‐hydrosilylation reactions with alkynes, dihydrosilanes (R2SiH2) under catalysis of Au/TiO2 lead to cis‐1,2‐dehydrogenative disilylation reactions at room temperature with high selectivity. The disilyl adducts can be further functionalized through a one‐pot procedure, catalyzed by the same catalyst, to form substituted 2,5‐dihydro‐1,2,5‐oxadisiloles or 1,4‐disila‐2,5‐cyclohexadienes.

Silylation reactions on nanoporous gold via homolytic Si–H activation of silanes

“…The formations of hydrogen gas and Au–Si species of type A were also documented by the Stratakis group in their Au/TiO 2 NP catalysed cis -1,2-disilylation of alkynes. 64 We believe that at higher temperature the formation of hydrogen gas was more favourable, thus the ratio of B / A becomes bigger. A radical type C–O bond cleavage of the cyclic ether can be triggered either by the intermediate A or by the intermediate B , leaving the radical on the more substituted carbon ( i.e.…”

Gold‐Catalyzed Cross‐Coupling Reactions: An Overview of Design Strategies, Mechanistic Studies, and Applications

“…[394] 7.4. [395,397,398] Similarly,u nder ambient conditions, the cis-silaboration and diboration reactions could be carried out by using heterogeneous gold catalysis. Stratakis et al hypothesized that Au nanoparticles supported on TiO 2 could be utilized to activate the SiÀSi bond toward CÀSi bond-forming reactions.…”

Supported Au Nanoparticles‐Catalyzed Regioselective Dehydrogenative Disilylation of Allenes by Dihydrosilane

“…From a mechanistic point of view (Scheme ), we invoke the same arguments regarding the Au/TiO 2 ‐catalyzed dehydrogenative disilylation of alkynes, as well as the regioselective Au/TiO 2 ‐catalyzed diboration or silaboration of allenes . Thus, the disilyl HEt 2 Si‐Au n ‐SiEt 2 H species ( I ) generated from the dehydrogenative coupling between two molecules of Et 2 SiH 2 on the surface of Au nanoparticle (Au n ) react with the allene forming intermediate II , which then collapses into the final products. The regioselectivity of addition of the two silyl units on the terminal double bond is attributed to steric reasons, just as in the corresponding diboration or silaboration.…”

“…Dihydrosilanes (R 2 SiH 2 ), on the other hand, exhibit a different mode of reactivity as compared to simple monohydrosilanes (R 3 SiH). For example, we have recently reported the predominant Au/TiO 2 ‐catalyzed cis ‐dehydrogenative disilylation of alkynes by dihydrosilanes, instead of the anticipated hydrosilylation. Immediately after, Li and co‐workers observed that certain cyclic ethers may undergo AuNPore‐catalyzed dehydrogenative disilylation by a dihydrosilane.…”