Synthesis of an NHC-Coordinated Dialkyldisilavinylidene and Its Oxidation Providing a Silicon Analog of an Acetolactone

Although
isolable silicon analogs of acetylene have been extensively
studied, the silicon analogs of vinylidene, which is a short-lived
isomer of acetylene, remain scarce. Herein, we report isolable NHC-coordinated
dialkyldisilavinylidene 1 synthesized by the reduction
of a tetrabromodisilane featuring a bulky alkyl protecting group. 1 was fully characterized by a combination of multinuclear
NMR spectroscopy, high-resolution mass spectrometry, elemental analysis,
and X-ray diffraction analysis. The UV–vis spectrum and DFT
calculations disclosed that 1 possesses an SiSi
double bond and lone pair electrons on the terminal Si atom coordinated
by the NHC. 1 reacted with N2O and B­(C6F5)3 to provide a silicon analog of
an acetolactone stabilized by a Lewis base and a Lewis acid (4).