Asymmetric ring-closing metathesis with a twist.

Area of Science:

• Organometallic Chemistry
• Asymmetric Catalysis
• Synthetic Organic Chemistry

Background:

• Ring-closing metathesis is a powerful tool for synthesizing cyclic molecules.
• Developing highly active and selective catalysts for asymmetric transformations remains a key challenge in organic synthesis.

Purpose of the Study:

• To introduce a novel molybdenum-based catalyst for asymmetric ring-closing metathesis.
• To investigate the mechanism behind the catalyst's unprecedented activity.

Main Methods:

• Synthesis of a molybdenum complex featuring monodentate silane ligands (Si = SitBuMe(2)).
• Evaluation of the catalyst's performance in asymmetric ring-closing metathesis reactions with various substrates.
• Mechanistic studies to probe the catalyst's structural fluxionality and double inversion at the metal center.

Main Results:

• The catalyst demonstrated high activity and selectivity in asymmetric ring-closing metathesis for a broad substrate scope.
• Unprecedented catalytic activity was attributed to the catalyst's structural fluxionality, allowing a double inversion at the molybdenum center per catalytic cycle.
• The catalyst was successfully employed in a key metathesis step towards the synthesis of (+)-quebrachamine.

Conclusions:

• The developed molybdenum catalyst represents a significant advancement in asymmetric ring-closing metathesis.
• The catalyst's unique mechanism involving double inversion offers new insights into catalytic cycles.
• This catalyst holds promise for the efficient synthesis of complex chiral molecules.