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Heterogeneous Removal of Water-Soluble Ruthenium Olefin Metathesis Catalyst from Aqueous Media Via Host-Guest Interaction
Published on: August 23, 2018
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Reactivity and selectivity differences between catecholate and catechothiolate Ru complexes. Implications regarding
R Kashif M Khan1, Sebastian Torker, Amir H Hoveyda
1Department of Chemistry, Merkert Chemistry Center, Boston College , Chestnut Hill, Massachusetts 02467, United States.
Journal of the American Chemical Society
|October 1, 2014
Summary
Ruthenium catechothiolate complexes unexpectedly achieve high Z-selectivity in olefin metathesis. Unlike catecholates, they maintain structural integrity and determine stereochemistry during metallacyclobutane formation, not alkene coordination.
Area of Science:
- Organometallic Chemistry
- Catalysis
- Organic Synthesis
Background:
- Olefin metathesis is a crucial reaction in organic synthesis.
- Achieving high stereoselectivity, particularly Z-selectivity, remains a challenge.
- Ruthenium complexes are widely used catalysts for olefin metathesis.
Purpose of the Study:
- To elucidate the origins of unexpected Z-selectivity in Ru catechothiolate complexes.
- To understand the mechanistic differences between catechothiolate and catecholate Ru complexes in olefin metathesis.
- To revise existing models for Z-selectivity in olefin metathesis.
Main Methods:
- Synthesis and characterization of Ru catechothiolate and catecholate complexes.
- Evaluation of catalytic activity and Z-selectivity in olefin metathesis reactions.
- Density Functional Theory (DFT) calculations to probe reaction mechanisms.
Main Results:
- Ru catechothiolate complexes exhibit exceptional Z-selectivity, unlike catecholate derivatives.
- Catechothiolate complexes maintain structural integrity under reaction conditions, whereas catecholates degrade.
- DFT calculations reveal stereochemistry is determined during metallacyclobutane formation for catechothiolates, contrasting with alkene coordination for catecholates.
Conclusions:
- The enhanced Z-selectivity of Ru catechothiolate complexes stems from their unique mechanistic pathway.
- Structural integrity and electronic factors, in addition to sterics, are critical for controlling Z-selectivity.
- This study necessitates revising current models of stereoselectivity in olefin metathesis.
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