Chromium-Mediated Coupling for Halichondrin Synthesis
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Solution Overview
Problem
Current synthetic methods for halichondrins and their analogs are complex and lack a unified, practical approach for synthesizing key building blocks, such as C1-C19 and C20-C38, which hinders efficient access to these marine natural products and their derivatives.
Innovation Solution
Development of chromium-mediated coupling reactions for synthesizing halichondrins, specifically an efficient method for preparing the C1-C19 and C20-C38 building blocks using chromium catalysts with optional nickel and zirconium catalysts, enabling asymmetric induction and selective coupling of halo-enone, halo-enone ketal, and halo-acetylenic substrates with aldehydes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional synthetic methods are used for halichondrins, then the synthesis can be completed, but the process is complex and lacks a unified, practical approach for synthesizing key building blocks
Solution Approach 1:
The synthesis of halichondrins is divided into modular building blocks (C1-C19 and C20-C38 segments) that can be independently synthesized and then coupled together. This segmentation allows for a unified, practical approach to synthesizing complex halichondrin structures by assembling pre-prepared modules through chromium-mediated coupling reactions.
Solution Approach 2:
Chromium catalysts serve as intermediaries to facilitate the coupling reactions between building blocks. The chromium-mediated coupling system acts as a mediator that enables selective and efficient joining of C1-C19 and C20-C38 segments, simplifying the overall synthetic process while maintaining high practicality.
2Manufacturing precision
If conventional coupling methods are used, then building blocks can be joined, but stereoselective installation of chiral centers is not achieved
Solution Approach 1:
The chromium-mediated coupling system incorporates asymmetric induction to achieve stereoselective installation of chiral centers during the coupling of building blocks. This asymmetry principle allows for precise control over stereochemistry while maintaining efficient synthesis through catalytic processes.
Solution Approach 2:
The chromium catalyst system modifies reaction parameters (such as oxidation state, coordination geometry, and ligand environment) to enable both high stereoselectivity and efficiency. By changing the chemical parameters of the coupling reaction, the system achieves precise stereocontrol without sacrificing productivity.
3Productivity
If multiple separate synthesis routes are used for C1-C19 and C20-C38 building blocks, then each block can be synthesized, but the overall process lacks convergence and efficiency
Solution Approach 1:
The synthesis strategies for C1-C19 and C20-C38 building blocks are merged into a unified convergent approach. Both building blocks are synthesized using compatible methodologies that enable their efficient coupling through chromium-mediated reactions, increasing overall productivity by reducing the number of separate synthetic routes.
Solution Approach 2:
The building blocks C1-C19 and C20-C38 are prepared in advance using pre-optimized synthesis routes before the final coupling step. This preliminary action allows for independent optimization of each building block synthesis while maintaining overall convergence and efficiency in the complete halichondrin synthesis.
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 approach provides a practical and efficient synthesis of halichondrin building blocks, facilitating the production of halichondrins and their analogs by enabling stereoselective installation of chiral centers and selective coupling reactions, thereby simplifying the synthesis of these biologically active compounds.
Implementation Method 1
chromium-mediated coupling reactions for synthesizing halichondrins, specifically an efficient method for preparing the C1-C19 and C20-C38 building blocks using chromium catalysts with optional nickel and zirconium catalysts
Implementation Method 2
transmetallation of the resultant Ni(II)-species to Cr(II)Cl2 to form alkenyl Cr(III)-species
Implementation Method 3
oxidative addition of Ni(0), formed from NiCl2 via reduction with CrCl2 in situ, to an alkenyl halide/triflate to form an alkenyl Ni(II)-species
Implementation Method 4
enabling asymmetric induction and selective coupling of halo-enone, halo-enone ketal, and halo-acetylenic substrates with aldehydes
Implementation Method 5
stereoselective installation of chiral centers
Data Source
AI summary
The present invention provides unified synthesis of the C1-C19 building blocks of halichondrins and analogs thereof using selective coupling of poly-halogenated nucleophiles in chromium-mediated coupling reactions. The present invention also provides a practical and efficient synthesis of C20-C38 building blocks of halichondrins and analogs thereof. Also provided herein are general methods of selective activation and coupling of poly-halogenated analogs with an aldehyde. The provided coupling reactions are selective for halo-enone and halo-acetylenic ketal over vinyl halide and halide attached to a sp hybridized carbon. The provided efficient selective coupling reactions can allow easy access to the C1-C19 building blocks and C20-C38 building blocks of halichondrins and analogs thereof with limited or no purification or separation of the intermediates.