Brønsted Acid Catalyzed Alkyne Oxygenative Coupling
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Solution Overview
Problem
Current methods for synthesizing 1,1-diaryl compounds using metal-carbene intermediates are limited by the instability of carbene intermediates, require vigorous conditions, and involve trace metal impurities, making them unsuitable for pharmaceutical production and restricting the range of applicable nucleophiles.
Innovation Solution
A method using a Brønsted acid to activate alkyne compounds and form a metal-free reactive intermediate, allowing for intermolecular oxygenative coupling reactions with various nucleophiles under mild conditions, avoiding the use of transition metals and achieving high selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If transition metal catalysts (Rh, Cu, Au) are used to form carbene intermediates for synthesizing 1,1-diaryl compounds, then the synthesis can proceed under conventional conditions, but the method produces trace metal impurities that are problematic for pharmaceutical applications and restricts the range of applicable nucleophiles
Solution Approach 1:
The invention extracts and eliminates the transition metal catalyst from the reaction system, replacing it with a Brønsted acid catalyst. This removes the source of metal impurity contamination while preserving the core oxygenative coupling reaction mechanism, enabling pharmaceutical-grade synthesis without trace metal residues
Solution Approach 2:
The invention replaces expensive transition metal catalysts (Rh, Cu, Au) with inexpensive Brønsted acid catalysts that can be easily removed and do not leave persistent contaminants. The acid catalyst serves its function and can be completely eliminated from the final product, unlike metal catalysts that leave trace impurities
2Adaptability or versatility
If metal-carbene intermediates are used for the oxygenative coupling reaction, then the reaction can proceed with various nucleophiles, but the carbene intermediates are very unstable and require very vigorous reaction conditions
Solution Approach 1:
The invention changes the fundamental reaction parameters by replacing metal-carbene intermediates with protonated alkyne intermediates. This substitution stabilizes the reactive intermediate, allowing the reaction to proceed under mild conditions (room temperature, atmospheric pressure) while maintaining versatility with various nucleophiles including electron-rich arenes, phenols, and indoles
3Ease of manufacture
If excess acid or high temperature is used to drive the metal-free oxygenative coupling reaction, then the reaction can proceed without transition metals, but the excessive conditions limit the applicable functional groups and restrict reactions to intramolecular only
Solution Approach 1:
The invention optimizes the acid catalyst parameters by selecting specific Brønsted acids with appropriate strength (pKa values) and using catalytic rather than stoichiometric amounts. This fine-tuning of acid parameters enables metal-free synthesis while maintaining mild conditions that preserve functional group compatibility and allow intermolecular coupling reactions
Solution Approach 2:
The invention introduces a carefully selected Brønsted acid as an intermediary that facilitates the formation of stable protonated alkyne intermediates. This intermediary enables the reaction to proceed under mild conditions without requiring excess acid or high temperature, thus expanding substrate scope to include various functional groups and intermolecular coupling partners
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 economical synthesis of 1,1-diaryl, 1,1-diheteroaryl, and 1,4-dicarbonyl compounds with high selectivity and reduced yield loss, suitable for pharmaceutical and agrochemical applications, while avoiding metal impurities and excessive oxidation.
Implementation Method 1
activating an alkyne compound (e.g., an ynamide) using a Brønsted acid as a catalyst
Implementation Method 2
induce a reaction of the activated alkyne compound and a N—O bond oxidant to form an adduct intermediate
Data Source
AI summary
The present disclosure relates to a method for preparing various physiologically active pharmaceutical ingredients, such as a 1,1-diaryl compound and a 1,1-diheteroaryl compound (specifically, a 1,1-diaryl carbonyl compound), in an economical and convenient manner under mild conditions without using an expensive transition metal catalyst by activating an alkyne compound (e.g., an ynamide) using a Brønsted acid as a catalyst to induce a reaction of the activated alkyne compound and a N—O bond oxidant to form an adduct intermediate and then inducing a coupling reaction of the adduct intermediate with various nucleophilic organic compounds (e.g., a nucleophilic arene compound).