An amplified Ylidic "half-parent" iminosilane LSi═NH

Area of Science:

• Organosilicon Chemistry
• Catalysis
• Organic Synthesis

Background:

• Metal-free C-H activation is a highly sought-after transformation in synthetic chemistry.
• Aminosilanes are versatile reagents, but their reactivity in C-H activation remains underexplored.
• The development of efficient and selective C-H activation methods is crucial for streamlined synthesis.

Purpose of the Study:

• To investigate the reactivity of a novel aminosilane, LSiBr(NH2), in C-H activation reactions.
• To explore metal-free aromatic C-H activation pathways.
• To elucidate the mechanism of this transformation and identify key intermediates.

Main Methods:

• Reaction of LSiBr(NH2) with lithium bis(trimethylsilyl)amide in the presence of pyridine or 4-dimethylaminopyridine (DMAP).
• Isolation and full characterization of aminosilane products.
• Isotope labeling experiments and Density Functional Theory (DFT) calculations.

Main Results:

• Successful metal-free aromatic C-H activation of pyridine and DMAP at room temperature.
• Isolation of novel aminosilane products LSi(dmap)NH2 and LSi(pyridine)NH2.
• Evidence for the formation of a key "half-parent" iminosilane intermediate (LSi═NH), which was trapped by benzophenone and trimethylsilylazide.

Conclusions:

• The study presents a novel metal-free aromatic C-H activation strategy facilitated by an aminosilane.
• The reaction mechanism involves a transient iminosilane intermediate with amplified ylidic character.
• This work expands the synthetic utility of aminosilanes and provides insights into C-H activation mechanisms.