Tuning the Selectivity of AuPd Nanoalloys towards Selective Dehydrogenative Alkyne Silylation

Abstract

The cross‐dehydrogenative coupling of terminal alkynes and hydrosilanes catalyzed by AuPd nanoalloys is described. Metal nanoparticles are readily prepared in 15 minutes from commercially available and cheap starting materials by using a photochemical approach. The ratio of Au and Pd in the alloys heavily influences their reactivity. These cooperative nanoalloy catalysts tolerate a large number of functional groups (e.g., free amines and acids), operate at room temperature under air atmosphere at low loading (2 mol %), and the cross‐dehydrogenative coupling can easily be scaled up.

Cross‐Dehydrogenative Alkynylation: A Powerful Tool for the Synthesis of Internal Alkynes

“…Despite the fact that only monohydrosilanes were demonstrated under the reaction conditions, the alkynes scope was general, and both aromatic and aliphatic terminal alkynes including acetylene gas worked well, leading to the production of various silylated alkynes. The cross‐dehydrogenative coupling between terminal alkynes and hydrosilanes to form silylated alkynes was also accomplished by AuPd nanoalloys on PEG200 and an unsupported nanoporous gold catalyst (AuNPore) with the use of O 2 as the terminal oxidant. Ytterbium and calcium complexes were also reported to have catalytic activity toward the spC−Si bond‐forming reactions.…”

Recent Advances in the Functionalization of Terminal and Internal Alkynes

“…In 2019, Studer et al elegantly developed first crossdehydrogenative coupling (CDC) method, catalyzed by AuPd nanoalloy for the synthesis of alkynylsilanes from terminal alkynes and hydrosilanes (Scheme 31). [31] This strategy tolerates Scheme 28. Cobalt-catalyzed synthesis of enantioenriched 1,1-silylboryl alkanes through asymmetric 1,1-silylboration of alkynes using Xantphos as ligand.…”

“…elegantly developed first cross‐dehydrogenative coupling (CDC) method, catalyzed by AuPd nanoalloy for the synthesis of alkynylsilanes from terminal alkynes and hydrosilanes (Scheme 31). [31] This strategy tolerates a large number of functional groups under the optimized conditions of 2 mol% Au 0.4 Pd 0.6 @PEG2000, 1 equiv. of ethyl phenylpropiolate and 0.5 equiv.…”

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

“…Moreover, with a few exceptions, [14][15][16][17] the vast majority of such strategies are based on catalysis utilizing transition metals. [18][19][20][21] This in turn can lead to reduced selectivity and efficiency due to possible competition between coupling and addition routes (hydrosilylation). 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.…”

“…Unfortunately, this approach is completely impractical for the preparation of a highly important TMS‐protecting group (TMS=trimethylsilyl), due to the pyrophoricity of gaseous Me 3 SiH and its lightest congeners. Moreover, with a few exceptions, [14–17] the vast majority of such strategies are based on catalysis utilizing transition metals [18–21] . This in turn can lead to reduced selectivity and efficiency due to possible competition between coupling and addition routes (hydrosilylation).…”