Z-Selective Cross-Metathesis and Homodimerization of 3E-1,3-Dienes: Reaction Optimization, Computational Analysis,...

Area of Science:

• Organic Chemistry
• Catalysis
• Synthetic Chemistry

Background:

• Olefin metathesis is a powerful carbon-carbon bond-forming reaction.
• Developing selective catalysts for diene substrates remains a challenge.
• Z-selective catalysts are crucial for synthesizing specific olefin geometries.

Purpose of the Study:

• To describe Z-selective olefin metathesis reactions using 3E-1,3-dienes.
• To detail a procedure for homodimerization and cross-metathesis with terminal alkenes.
• To demonstrate the utility of a novel ruthenium catalyst.

Main Methods:

• Utilized Z-selective cyclometalated ruthenium benzylidene catalysts.
• Employed 3E-1,3-dienes in homodimerization and cross-metathesis reactions.
• Leveraged catalyst chemoselectivity for terminal alkenes over internal E-alkenes.

Main Results:

• Achieved high yields of internal E,Z-diene cross-metathesis products.
• Demonstrated tolerance of various functional groups.
• Required only a small excess (1.5 equiv) of the diene coupling partner.
• Computational studies supported a diene-first reaction pathway.

Conclusions:

• The developed method provides efficient access to E,Z-dienes.
• This reaction is valuable for the rapid assembly of complex molecular targets.
• Successfully synthesized two insect pheromones, showcasing the method's practical application.