Ring-Closing Olefin Metathesis Catalyzed by Well-Defined Vanadium Alkylidene Complexes

Area of Science:

• Organometallic Chemistry
• Polymer Science
• Catalysis

Background:

• Vanadium catalysts show promise in olefin metathesis, but their use in organic synthesis is limited.
• Existing vanadium alkylidenes face challenges in routine application.

Purpose of the Study:

• To develop well-defined vanadium chloride alkylidene phosphine complexes for ring-closing olefin metathesis.
• To assess the catalytic activity and functional group tolerance of these new vanadium catalysts.

Main Methods:

• Synthesis of well-defined vanadium chloride alkylidene phosphine complexes.
• Evaluation of catalytic performance in ring-closing olefin metathesis reactions.
• Investigation of catalyst stability and degradation pathways through reactions with ethylene and olefins.

Main Results:

• The first example of ring-closing olefin metathesis catalyzed by vanadium chloride alkylidene phosphine complexes is reported.
• The developed catalysts exhibit tolerance to diverse functional groups including ethers, esters, amides, amines, and sulfonamides.
• Catalyst degradation is attributed to β-hydride elimination and bimolecular decomposition, influenced by imido group and phosphine properties.

Conclusions:

• Well-defined vanadium catalysts are effective for ring-closing olefin metathesis.
• Catalyst stability and activity are modulated by ligand design (imido and phosphine groups).
• Understanding degradation pathways is crucial for further catalyst development.