Metal‐Free Catalytic Hydrogenolysis of Silyl Triflates and Halides into Hydrosilanes**

Abstract

The metal‐free catalytic hydrogenolysis of silyl triflates and halides (I, Br) to hydrosilanes is unlocked by using arylborane Lewis acids as catalysts. In the presence of a nitrogen base, the catalyst acts as a Frustrated Lewis Pair (FLP) able to split H2 and generate a boron hydride intermediate capable of reducing (pseudo)halosilanes. This metal‐free organocatalytic system is competitive with metal‐based catalysts and enables the formation of a variety of hydrosilanes at room temperature in high yields (>85 %) under a low pressure of H2 (≤10 bar).

Metal‐Free Catalytic Hydrogenolysis of Chlorosilanes into Hydrosilanes with “Inverse” Frustrated Lewis Pairs**

“…20 % yield (Scheme 3 and see Supporting Information Section 2.2.1). Of interest, no reaction was observed by 1 H NMR between Me 3 SiCl and BTPP in dichloromethane [11] . Moreover, we already showed in a previous report that Me 3 SiCl is more reactive than [Me 3 SiBTPP]Cl for hydride transfers [9] .…”

“…To avoid the use of noble metal complexes, we considered the use of boron‐based organocatalysts, able to engage in Frustrated Lewis Pairs (FLPs) reactivity to activate H 2 and generate borohydrides (Scheme 2), the latter species being known to react with chlorosilanes [10] . We have previously reported the first metal‐free hydrogenolysis of silyl triflate and halides (I, Br) into hydrosilanes with a variety of di‐ or triarylfluoroboranes, which behave as classical FLPs with amines, such as 2,2,6,6‐tetramethylpiperidine (TMP) [11] . A similar procedure was described for the hydrodehalogenation of benzyl halides [12] .…”

Triphenylborane in Metal-Free Catalysis

“…Recent developments concerning iridium- and ruthenium-catalyzed hydrogenations of organosilicon compounds [ 66 , 67 , 68 , 69 , 70 ] motivated the Cantat group to design FLP catalysts for the metal-free hydrogenation of various organosilanes with Si-X bonds (X = OTf, I, Br, Cl) [ 71 ]. After extensive screening, B(2,6-F 2 -C 6 H 3 ) 3 as the Lewis acid combined with stochiometric amounts of 2,2,6,6-tetramethylpiperidine (TMP) as the base was identified as the most effective FLP catalyst for the hydrogenation of Me 3 SiX (X = OTf, I, Br) to Me 3 SiH ( Scheme 9 ).…”

Transition Metal‐Free Catalytic C−H Silylation of Terminal Alkynes with bis(Trimethylsilyl)acetylene Initiated by KHMDS

“…In contrast, the concept of using silylacetylenes as an atypical coupling partner has occasionally been deployed and these strategies are not without their own disadvantage, including the use of fluoride reagents or/and expensive crown ethers, harsh conditions, lower chemoselectivity (e. g., the dimerization of phenylacetylenes) and narrow substrate scope. [22][23][24][25] Sustainable and eco-friendly synthetic approaches proceeded by the main-group catalysis have gained recent significant attention, [26][27][28][29][30][31][32][33][34][35][36] especially due to the fact of the high abundance of such catalytic species. This in turn, in combination with scientifically important CÀ H and XÀ H/C bond activations (where X = Si, B, Ge, etc.)…”

“…Sustainable and eco‐friendly synthetic approaches proceeded by the main‐group catalysis have gained recent significant attention, [26–36] especially due to the fact of the high abundance of such catalytic species. This in turn, in combination with scientifically important C−H and X−H/C bond activations (where X=Si, B, Ge, etc.)…”