Quinoline-2,3-Fused Nine-Membered Ring Synthesis via Organocatalysis
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Solution Overview
Problem
The synthesis of quinoline-2,3-fused nine-membered ring scaffold compounds is challenging due to increased ring strain and entropy, with existing methods often requiring metal catalysis and limited reports on 2,3-quino-nine-membered rings, and there is a need for effective antimicrobial agents against plant fungal diseases that cause significant agricultural losses.
Innovation Solution
A quinoline-2,3-fused nine-membered ring compound is synthesized through a hydride transfer reaction using a quinoline-derived aniline compound and formaldehyde, with specific catalysts and solvents, achieving a high-yield, atom-economical, and environmentally friendly process, and showing excellent bactericidal activity against plant pathogens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metal catalysis is used for synthesizing quinoline-2,3-fused nine-membered ring compounds, then the synthesis can be achieved, but the process complexity and cost increase
Solution Approach 1:
The patent extracts and removes the metal catalyst from the synthesis system, replacing it with an organocatalyst (proline or its derivatives). This eliminates the need for complex metal catalysis systems while maintaining the ability to construct the nine-membered ring scaffold, thereby reducing device complexity and cost without sacrificing manufacturability
Solution Approach 2:
The patent employs simple, inexpensive organocatalysts (proline or its derivatives) that can be easily handled and disposed of, replacing expensive and sensitive metal catalysts. These organic catalysts are stable, non-toxic, and do not require special handling equipment, thus reducing device complexity while maintaining synthesis accessibility
2Reliability
If traditional multi-step synthesis methods are used for quinoline-2,3-fused nine-membered ring compounds, then the synthesis can be completed, but the time consumption and productivity decrease
Solution Approach 1:
The patent merges multiple synthesis steps into a single cascade reaction. The organocatalyst mediates a sequence of transformations (aldol condensation, dehydration, cyclization) that occur in one pot without isolating intermediates, thereby maintaining reliable synthesis completion while dramatically improving productivity by reducing time consumption and operational complexity
Solution Approach 2:
The patent employs preliminary substrate design with pre-installed functional groups (alkyne, ester, amide) that are positioned to undergo spontaneous cyclization after the initial organocatalyzed aldol condensation. This preliminary arrangement allows the complex nine-membered ring formation to occur efficiently in a single operation, improving productivity while ensuring reliable synthesis completion
3Shape
If ring expansion strategies are used to construct nine-membered rings, then the scaffold can be formed, but the ring strain and entropy increase making synthesis challenging
Solution Approach 1:
The patent changes the reaction parameters by employing an organocatalytic mechanism with proline or its derivatives, which operates under mild conditions with controlled stereochemistry. This approach manages the ring strain and entropy challenges of nine-membered ring formation by providing a stepwise, catalyzed pathway that avoids the high-energy transitions required in traditional methods, thereby forming the desired scaffold without excessive synthesis complexity
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
The synthesized quinoline-2,3-fused nine-membered ring compound exhibits high inhibitory activity against common plant disease-related fungi, such as C. gloeosporioides, V. mali, F. oxysporum, B. cinerea, and G. graminis, offering potential as a plant fungicide with broad substrate scope and bioactivity.
Implementation Method 1
a hydride transfer reaction was developed for constructing the quinoline-2,3-fused nine-membered ring scaffold
Implementation Method 2
using specific catalysts and solvents, achieving a high-yield, atom-economical, and environmentally friendly process
Data Source
AI summary
The present disclosure discloses a quinoline-2,3-fused nine-membered ring scaffold compound, and a preparation method and application thereof as an effective component in a plant fungicide. The quinoline-2,3-fused nine-membered ring scaffold compound stated in the present disclosure is prepared by the following method including steps: mixing a quinoline-derived aniline compound and a formaldehyde compound, adding a solvent and a catalyst, controlling a system temperature, and reacting with stirring to obtain a quinoline-2,3-fused nine-membered ring compound. According to the present disclosure, a 1,6-hydride transfer/cyclization strategy is triggered by aldimine condensation, the quinoline-derived aniline compound and the formaldehyde compound are prepared into the quinoline-2,3-fused nine-membered ring compound with a wide substrate scope and a potential biological activity by a “one-pot synthesis method” quickly. The quinoline-2,3-fused nine-membered ring compound shows an excellent inhibitory activity against G. graminis, C. gloeosporioides, B. cinerea, V. mali, F. oxysporum and other plant disease-related fungi.