Norbornene based-sulfide-stabilized silylium ions: synthesis, structure and application in catalysis

Area of Science:

• Organosilicon Chemistry
• Catalysis

Background:

• Silylium ions are highly reactive silicon-containing cations.
• Stabilization of silylium ions is crucial for their practical application.
• Previous research focused on phosphine-stabilized silylium ions.

Purpose of the Study:

• To synthesize and characterize a novel norbornene-based sulfide stabilized silylium ion.
• To investigate the Lewis acidity and catalytic potential of the new silylium ion.
• To compare its reactivity with previously known silylium ions.

Main Methods:

• Synthesis of norbornene-based sulfide stabilized silylium ion 4.
• Nuclear Magnetic Resonance (NMR) spectroscopy for solution-state analysis.
• X-ray diffraction analysis for solid-state structure determination.
• Density Functional Theory (DFT) calculations for electronic structure and reactivity prediction.

Main Results:

• Successful synthesis and characterization of silylium ion 4.
• Experimental and computational evidence confirmed the S-Si interaction.
• DFT calculations predicted Lewis acid behavior towards acrylates.
• Silylium ion 4 demonstrated catalytic activity in Diels-Alder reactions with unreactive dienes.
• Silylium ion 4 showed efficacy in hydrodefluorination reactions.

Conclusions:

• The novel sulfide-stabilized silylium ion 4 is a stable and easy-to-handle Lewis acid catalyst.
• It exhibits unique reactivity compared to phosphine-stabilized counterparts.
• This silylium ion offers a promising platform for catalyzing challenging organic transformations.