Chiral Iridium Complex Asymmetric Hydrogenation for Enantiomeric Excess
Solution Overview
Problem
There is a strong need for an effective and industrial-scale synthesis of (2R,4'R)-tocopherols and (R,R)-isophytol, which are chiral substances with limited natural sources, requiring an efficient process to produce (6R,10R)-6,10,14-trimethylpentadecan-2-one, a key intermediate.
Innovation Solution
A multistep synthesis process involving the separation and asymmetric hydrogenation of a mixture of (3E,5E)/(3E,5Z)/(3Z,5E)/(3Z,5Z)-6,10-dimethylundeca-3,5,9-trien-2-one, using chiral iridium complexes and cis/trans isomerization catalysts to produce (6R,10R)-6,10,14-trimethylpentadecan-2-one efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If asymmetric hydrogenation is performed directly on the mixture of E/Z isomers, then the process complexity is reduced, but the manufacturing precision and enantiomeric excess of the product deteriorate
Solution Approach 1:
The patent applies preliminary action by performing cis/trans isomerization before asymmetric hydrogenation. The process first converts all E/Z isomers into a single desired isomer configuration, then proceeds with asymmetric hydrogenation. This preliminary isomerization step ensures that the subsequent hydrogenation operates on a uniform substrate, thereby maintaining high enantiomeric excess while managing process complexity through standardized reaction conditions.
Solution Approach 2:
The patent segments the synthesis process into distinct stages: (1) cis/trans isomerization to obtain pure (5E)-isomer, and (2) asymmetric hydrogenation to produce the chiral product. This segmentation allows each step to be optimized independently - the isomerization step ensures geometric purity while the hydrogenation step ensures enantiomeric purity, thereby resolving the contradiction between process simplicity and product precision.
2Productivity
If all isomers are converted to the desired product, then the productivity increases, but the manufacturing precision of individual isomer conversion deteriorates
Solution Approach 1:
The patent converts the harmful presence of unwanted E/Z isomers into a beneficial feature by using cis/trans isomerization catalysts. These catalysts transform the geometric isomers into the desired (5E)-configuration, turning what would be waste material into valuable substrate for the asymmetric hydrogenation step. This approach maximizes overall productivity while maintaining high conversion purity through selective catalysis.
Solution Approach 2:
The patent employs parameter changes by adjusting reaction conditions (catalyst selection, temperature, pressure) to control the isomerization and hydrogenation processes. By optimizing these parameters, the process achieves complete conversion of all isomers to the desired product with high stereoselectivity, thereby simultaneously improving productivity and maintaining manufacturing precision.
3Manufacturing precision
If separation steps are added to isolate desired isomers before hydrogenation, then the manufacturing precision improves, but the device complexity and loss of time increase
Solution Approach 1:
The patent uses cis/trans isomerization catalysts as intermediaries to convert unwanted isomers into the desired configuration rather than physically separating them. This chemical mediation approach replaces complex separation equipment and procedures with a simple catalytic transformation step, thereby improving manufacturing precision while reducing device complexity and processing time.
4Manufacturing precision
If asymmetric hydrogenation conditions are optimized for high enantiomeric excess, then the manufacturing precision improves, but the productivity and reaction speed deteriorate
Solution Approach 1:
By performing cis/trans isomerization as a preliminary step before asymmetric hydrogenation, the patent ensures that the hydrogenation reaction operates on a single geometric isomer configuration. This preliminary purification allows the use of optimized asymmetric hydrogenation conditions that achieve high enantiomeric excess without sacrificing reaction speed, as the catalyst operates on a uniform substrate with maximum efficiency.
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
This process allows for the high-quality production of the desired chiral product from isomeric mixtures, enabling industrial-scale production and maximizing the use of starting materials by converting non-desired isomers into the desired product.
Implementation Method 1
asymmetric hydrogenation using molecular hydrogen in the presence of a chiral iridium complex
Implementation Method 2
asymmetric hydrogenation using molecular hydrogen in the presence of a chiral iridium complex
Implementation Method 3
cis/trans-isomerization. The asymmetric hydrogenation, which is one of the key elements of this invention, can be improved in quality and speed
Data Source
Figure 1a~1c
Figure 2
Figure 3a~3c
AI summary
The present invention relates to a process of manufacturing (6R,10R) -6,10,14-trimethylpentadecan-2-one in a multistep synthesis from 6,10- dimethylundeca-3,5,9-trien-2-one. The process is very advantageous in that it forms in an efficient way the desired chiral product from a mixture of stereoisomers of the starting product.