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Alkene Isomerization Catalyzed by a Mn(I) Bisphosphine Borohydride Complex
Ines Blaha1, Stefan Weber1, Robin Dülger1
1Institute of Applied Synthetic Chemistry, TU Wien, Getreidemarkt 9/163-AC, A-1060 Wien, Austria.
ACS Catalysis
|September 12, 2024
Summary
This study introduces an additive-free manganese catalyst for isomerizing terminal alkenes to internal alkenes at room temperature. This inexpensive, nonprecious metal catalyst efficiently produces E-alkenes, offering a greener synthetic route.
Area of Science:
- Organometallic Chemistry
- Catalysis
- Organic Synthesis
Background:
- Alkene isomerization is crucial for synthesizing valuable internal alkenes.
- Existing methods often require precious metals or harsh conditions.
- Development of cost-effective and sustainable catalytic systems is highly desirable.
Purpose of the Study:
- To develop an additive-free catalytic system for alkene isomerization.
- To utilize an inexpensive, nonprecious metal catalyst for this transformation.
- To investigate the mechanism of manganese-catalyzed alkene isomerization.
Main Methods:
- Manganese-catalyzed isomerization of terminal alkenes.
- Use of a borohydride complex, cis-[Mn(dippe)(CO)2(κ2-BH4)], as the catalyst.
- Mechanistic investigations including stoichiometric reactions, in situ NMR, and computational studies.
Main Results:
- Efficient and selective conversion of terminal alkenes to internal E-alkenes using 2.5 mol % catalyst loading at room temperature.
- Demonstration of chain-walking isomerization at elevated temperatures.
- Elucidation of the catalytic mechanism involving M-H species, double bond insertion, and beta-hydride elimination.
Conclusions:
- An additive-free, room-temperature manganese-catalyzed alkene isomerization has been achieved.
- The developed catalytic system offers a cost-effective and selective method for producing internal E-alkenes.
- Mechanistic studies provide insights into the catalytic cycle, paving the way for further catalyst optimization.
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