Cyclic Peptide Synthesis via Ugi Condensation
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Solution Overview
Problem
The synthesis of cyclic peptides is hindered by thermodynamic and kinetic challenges, such as conformational preferences of linear peptides and the need for high dilution to prevent by-product formation, which results in low yields and selectivity, especially for peptides with fewer than seven residues, and limits late-stage modification of macrocyclic molecules.
Innovation Solution
A process involving the reaction of an amino acid or linear peptide with an isocyanide and an amphoteric amino aldehyde, using the Ugi four-component condensation, which shifts the chain/ring equilibrium and allows for efficient macrocyclization without the need for high dilution, enabling high yields and selectivity, and facilitates late-stage structural modification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional activation reagents are used for macrocyclization, then the peptide can be activated for cyclization, but the zwitterionic character is removed preventing ion pair formation, leading to unfavorable entropy and requiring high dilution
Solution Approach 1:
The invention changes the chemical parameters of the activation process by using carbodiimide reagents that preserve the zwitterionic character of the peptide, enabling ion pair formation and favorable entropy without requiring high dilution, thus reducing reaction time
Solution Approach 2:
The invention introduces an intermediary ion pair structure that mediates between the activated peptide and the cyclization transition state, stabilizing the conformation and enabling efficient macrocyclization without high dilution
2Manufacturing precision
If high dilution is used to prevent cyclodimerization and polymerization, then by-product formation is reduced, but reaction times become excessively long provoking background processes such as epimerization
Solution Approach 1:
The invention changes the concentration parameter from high dilution to moderate concentration by introducing a conformational constraint mechanism through ion pair formation, which prevents by-product formation without requiring extended reaction times
Solution Approach 2:
The invention performs preliminary conformational organization through ion pair formation and zwitterionic stabilization before the cyclization step, pre-organizing the peptide in a cyclization-competent conformation that prevents by-product formation even at higher concentrations
3Ease of manufacture
If linear peptides are used for macrocyclization, then the synthesis can proceed with standard reagents, but conformational preferences and chain/ring equilibrium create thermodynamic challenges leading to low yields
Solution Approach 1:
The invention changes the thermodynamic parameters by preserving and utilizing the zwitterionic character and ion pairing interactions, creating a favorable free energy landscape that drives the chain-to-ring transition and improves yields
Solution Approach 2:
The invention converts the typically unfavorable entropy of macrocyclization into a beneficial effect by harnessing the enthalpic stabilization from ion pair formation and zwitterionic interactions, which compensate for the entropic penalty and drive cyclization to completion
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 enables the production of cyclic peptides with high yields and selectivity, including medium-sized rings, and allows for seamless late-stage diversification, overcoming traditional synthesis limitations and achieving high diastereoselectivity and avoiding epimerization.
Implementation Method 1
A process involving the reaction of an amino acid or linear peptide with an isocyanide and an amphoteric amino aldehyde, using the Ugi four-component condensation
Data Source
AI summary
Macrocyclization of amino acids or linear peptides upon reaction with amphoteric amino aldehydes and isocyanides is provided.