C4'-Alkyl-Ether Heptamethine Cyanine Fluorophores
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Solution Overview
Problem
Current methods for preparing fluorescent small molecules, particularly near-infrared (near-IR) heptamethine cyanine fluorophores, face challenges such as inefficient condensation reactions, harsh conditions, and poor chemical stability, especially at the C4′ position, limiting their application in biological imaging due to instability and synthesis difficulties.
Innovation Solution
A synthetic method for producing stable heptamethine cyanine (Cy7) fluorophores with C4′-O-alkyl ether modifications, involving specific reaction conditions and reagents to form ions and conjugates suitable for near-IR imaging, including the use of maleimidyl and succinimidyl groups for bioconjugation, which enhances stability and bioconjugation capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard C4′-chloride exchange reaction is used to prepare C4′-O-alkyl ether cyanines, then the reaction proceeds through electron transfer SRN1 pathway, but the reaction fails due to poor kinetics of alkoxides and competitive addition to C2 position
Solution Approach 1:
The patent introduces an alternative reaction pathway using alkoxide nucleophiles under specific conditions (polar aprotic solvent, elevated temperature) to mediate the C4′-chloride exchange reaction, avoiding the failed electron transfer SRN1 pathway while achieving the desired C4′-O-alkyl ether product
Solution Approach 2:
The patent changes reaction parameters including using polar aprotic solvents (DMF, DMSO, acetonitrile), elevated temperatures (60-100°C), and specific alkoxide sources to enable the C4′-chloride exchange reaction to proceed successfully, overcoming the poor kinetics issue
2Use of energy by moving object
If conventional heptamethine cyanine fluorophores are used for near-IR imaging, then tissue penetration is improved, but chemical stability at C4′ position deteriorates
Solution Approach 1:
The patent applies local quality modification by introducing O-alkyl ether substituents specifically at the C4′ position of the cyanine fluorophore, maintaining the near-IR optical properties while locally enhancing chemical stability through the ether linkage that resists nucleophilic attack
3Ease of manufacture
If condensation reactions are used to prepare fluorescent small molecules, then fluorophores can be synthesized, but the reactions are inefficient and require harsh conditions
Solution Approach 1:
The patent changes reaction parameters by using polar aprotic solvents and elevated temperatures to enable efficient C4′-chloride exchange reactions, replacing inefficient conventional condensation reactions with a more productive nucleophilic substitution pathway
Data Source
AI summary
Embodiments of C4′-alkyl-ether heptamethine cyanine fluorophores according to general formula I, and pharmaceutically acceptable salts thereof, are disclosed. Methods of making and using the C4′-alkyl-ether heptamethine cyanine fluorophores also are disclosed.