Ruthenium Catalysts for Z-Selective Metathesis
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Solution Overview
Problem
Current metathesis reactions face challenges in achieving high stereoselectivity and efficiency, particularly in favoring the production of Z-olefins due to the reversible nature of olefin metathesis and isomerization to thermodynamically favored E-olefins, with existing Ru-catalysts typically exhibiting E-selectivity and diminished catalytic activity at higher conversions.
Innovation Solution
Development of new compounds with specific structures, such as those described in formulas I, I-a, I-b, and I-c, which act as Ru-based catalysts with bidentate or polydentate ligands, including carbene and aryloxide ligands, to promote metathesis reactions with high Z-selectivity and efficiency, even at low catalyst loadings and high turnover numbers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing Ru-catalysts are used for metathesis reactions, then catalytic activity is maintained, but Z-selectivity is poor and E-selectivity is favored
Solution Approach 1:
The patent applies local quality by designing ligands with specific localized electronic and steric properties around the ruthenium center. The ligands contain electron-withdrawing groups at specific positions that create a localized electronic environment favoring Z-olefin formation, while maintaining overall catalytic activity through the rest of the ligand structure.
Solution Approach 2:
The patent changes key parameters of the catalyst system by modifying ligand structure (introducing electron-withdrawing groups), adjusting catalyst loading (as low as 0.002 mol%), and optimizing reaction conditions to achieve both high Z-selectivity and sustained catalytic activity throughout the reaction.
2Productivity
If catalyst loading is reduced to improve efficiency, then cost and waste are reduced, but catalytic activity and stability diminish
Solution Approach 1:
The patent achieves high turnover numbers (up to 43,000) by optimizing multiple parameters simultaneously: ligand structure with electron-withdrawing groups, catalyst loading (0.002-0.1 mol%), and reaction conditions. This parameter optimization allows ultra-low catalyst loading while maintaining exceptional catalytic activity and stability.
Solution Approach 2:
The patent creates a composite catalyst system combining ruthenium center with specifically designed ligand structures containing electron-withdrawing groups. This composite structure enhances catalyst stability and activity, enabling high turnover numbers even at trace catalyst loadings.
3Productivity
If metathesis reaction proceeds to high conversion, then yield is improved, but catalyst activity diminishes due to isomerization to E-olefins
Solution Approach 1:
The patent applies preliminary anti-action by designing ligands that preemptively counteract the thermodynamic tendency toward E-olefin formation. The electron-withdrawing groups on the ligands create a catalytic environment that favors Z-olefin formation from the outset, preventing isomerization even as conversion increases to complete yield.
Solution Approach 2:
The patent changes the stereoselectivity parameter throughout the reaction by optimizing ligand structure and reaction conditions, allowing the reaction to proceed to complete conversion while maintaining high Z-selectivity. The catalyst remains active and selective even at high conversions where other catalysts fail.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These catalysts achieve exceptional Z-selectivity (typically >98:2 Z:E) and efficiency, allowing complete conversion at catalyst loadings as low as 0.002 mol% with turnover numbers up to 43,000, overcoming the limitations of existing Ru-catalysts by favoring Z-olefin production and maintaining catalytic activity.
Implementation Method 1
Catalysts for efficient Z-selective metathesis. The present invention provides compounds for promoting metathesis reactions with high stereoselectivity and/or efficiency.
Data Source
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AI summary
The present application provides, among other things, compounds and methods for metathesis reactions. In some embodiments, provided compounds promote highly efficient and highly Z-selective metathesis. In some embodiments, provided compounds and methods are particularly useful for producing allyl alcohols. In some embodiments, provided compounds have the structure of formula I. In some embodiments, provided compounds comprise ruthenium, and a ligand bonded to ruthenium through a sulfur atom.