Synergistic Gold‐Silicon Catalysis: Unravelling Alkynyl Gold Reactivity and Application to the High‐Performance C‐Alkynylation of Glycals

Within the synergistic gold-silicon catalysis concept, we have reported here the efficient and highly α-stereoselective Au-Si-catalyzed alkyne transfer from 1-trimethylsilylalkynes to glycals, at room temperature and at low loading (0.2-1 mol%). The synthesized and bench-stable (F5Ph)3PAuNTf2 complex was found instrumental to achieve such C-alkynylation reaction, through the in situ generation of both trimethylsilyl triflimide and alkynylgold complex from 1-trimethylsilylalkynes. This coupling has been deployed routinely on a wide combination of glycal donors and as efficiently with either aryl or alkyl 1-trimethylsilylalkyne aglycons, functionalized or not. This method could also be applied to the synthesis of a pseudo-C-disaccharide. DFT mechanistic investigations confirmed for the first time that alkynylgold species i) exhibit suitable nucleophilic character, even when they carry highly electrophilic ligands, and ii) that they react as "classical" organometallics and not through their possible carbenic form in reaction with oxacarbenium electrophiles.