Iron-catalyzed sequential hydrosilylation.

Area of Science:

• Organometallic Chemistry
• Asymmetric Catalysis
• Silicon Chemistry

Background:

• Hydrosilylation is a key reaction in organosilicon chemistry.
• Developing selective catalytic methods for complex silicon-containing molecules remains a challenge.
• Benzosilacycles offer unique structural motifs for exploring new chemical transformations.

Purpose of the Study:

• To develop a highly regio-, diastereo-, and enantioselective iron-catalyzed sequential hydrosilylation of o-alk-n-enyl-phenyl silanes with alkynes.
• To synthesize chiral, fully carbon-substituted, silicon-stereogenic benzosilacycles.
• To investigate the electronic effects of ligands on selectivity and propose a reaction mechanism.

Main Methods:

• Iron-catalyzed sequential hydrosilylation using various alkynes.
• Synthesis of 5-, 6-, and 7-membered benzosilacycles.
• Triple hydrosilylation reactions for silicon-stereogenic compounds.
• Variable Time Normalization Analysis (VTNA) and H/D exchange experiments for mechanistic studies.

Main Results:

• Achieved 60-94% yields for benzosilacycles with up to 95:5 rr, 95:5 dr, and 99% ee.
• Successfully synthesized chiral, fully carbon-substituted, silicon-stereogenic benzosilacycles.
• Demonstrated the significant electronic effect of ligands on regioselectivity and enantioselectivity.
• Proposed a plausible reaction mechanism supported by experimental data.

Conclusions:

• The developed iron-catalyzed method provides efficient access to complex benzosilacycles with high stereochemical control.
• Ligand design is crucial for tuning the selectivity of hydrosilylation reactions.
• The study advances the synthetic utility of iron catalysis in silicon chemistry and provides mechanistic insights.