Supported gold nanoparticles on metal oxides (1 mol %) catalyze for the first time the cis-selective disilylation of terminal alkynes by 1,2-disilanes in isolated yields up to 94%. It is likely that the reaction proceeds through oxidative insertion of the σ Si-Si bond of disilanes on gold followed by 1,2-addition to the alkyne.

The first example of Au-catalyzed hydrosilylation of allenes is presented using recyclable gold nanoparticles as catalyst, without the requirement of any external ligands or additives. The hydrosilane addition takes place on the more substituted double bond of terminal allenes in a highly regioselective manner. The observed regioselectivity/reactivity modes are attributed to steric and electronic factors.

Under catalysis by commercially available supported Au nanoparticles on TiO2 (1 mol %), terminal allenes undergo diboration and silaboration exclusively on the terminal double bond, in high yields and stereoselectivity. In silaboration, the boron moiety (Bpin) is attached on the terminal carbon and the silyl group on the sp-C, a regioselectivity pattern that is unusual. No ligands or additives are required, while the catalyst is recyclable and reusable. The selectivity is rationalized in terms of a π-allyl type or an η-1 complex intermediate with an apparent allylic carbocationic character, as revealed through the use of cyclopropyl allenes as sensitive probes.

Au nanoparticles supported on TiO 2 (1 mol %) catalyze the quantitative cycloisomerization of conjugated allenones into furans under very mild conditions. The reaction rate is accelerated by adding acetic acid (1 equiv), but the acid does not participate in the protodeauration step as in the corresponding Au(III)-catalyzed transformation. The process is purely heterogeneous, allowing thus the recycling and reuse of the catalyst effectively in several runs.

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.

The Au/TiO 2 -catalyzed reaction between 1,1,2,2-tetramethyldisilane and terminal alkynes yields substituted 1,4-disila-2,5-cyclohexadienes (1,1,4,4-tetramethyl-1,4dihydro-1,4-disilines) in moderate to good yields. The reaction proceeds via initial Si−Si activation of disilane by gold nanoparticles to form with alkynes isolable cis-1,2-disilyl adducts (cis-1,2-bis(dimethylsilyl)ethenes), which, under the reaction conditions, undergo a Au-catalyzed dehydrogenative cycloaddition to a second alkyne molecule, forming the final cycloadducts.

Commercially available Au nanoparticles supported on TiO2 were used to catalyze the cis diboration of terminal and internal alkynes with bis(pinacolato)diboron. The products were obtained in excellent yields by using milder conditions, shorter reaction times, and lower catalyst loadings than those required for a heterogeneous Au nanopore catalyst. The catalytic system could be recovered and reused for five consecutive runs without any loss of activity. The combination of bis(pinacolato)diboron with the 1,2‐disilane in the presence of Au/TiO2 allowed for the σ‐bond metathesis to take place and the in situ formation of the Au nanoparticle‐tethered silylborane. Given that the Au‐catalyzed silaboration of alkynes is faster than the rates of the corresponding disilylation and diboration pathways, we were able to achieve the indirect silaboration of alkynes with good chemoselectivities (65–85 %) without the direct use of silylboranes, which are expensive and difficult to synthesize.

Aromatic aldehydes and acetophenones undergo silylative pinacol-type reductive dimerization in their reaction with silylborane pinB-SiMe 2 Ph (pin: pinacolato) catalyzed by supported Au nanoparticles on TiO 2 . It is proposed that after initial activation of silylborane by Au nanoparticles and addition to the carbonyl functionality of an aromatic aldehyde or ketone, an aryl silyloxy radical is generated from the collapse of the intermediate adduct, which then dimerizes through a chain process. The silyloxy radical was almost quantitatively trapped in the presence of TEMPO.