Redox Dehydration Catalysts for Amide Bond Formation
Solution Overview
Problem
Current methods for forming amide bonds, essential in biological materials and therapeutics, face challenges such as high temperature requirements, compatibility issues with reactants, and the use of hazardous or expensive reagents, along with concerns like epimerization and by-product formation, limiting their efficiency and safety.
Innovation Solution
The use of catalytic molecules like heterocyclic thiolamide, S-acylthiosalicylamide, disulfide, selenium-containing heterocycles, and diselenide compounds that catalyze the transformation of hydroxy group-containing compounds into amides, esters, and other carbon-to-heteroatom or carbon-to-carbon transformations, facilitating amide bond formation at neutral pH and room temperature with copper salts and phosphites.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high temperature conditions are used to eliminate water in amide bond formation, then the reaction proceeds, but the integrity of the reacting compounds is compromised
Solution Approach 1:
The patent changes the temperature parameter from high temperature (>200°C) to room temperature conditions, enabling the reaction to proceed under milder conditions that preserve compound integrity while maintaining productivity through catalytic acceleration
Solution Approach 2:
The patent introduces coupling reagents as intermediary substances that facilitate the amide bond formation reaction at room temperature, acting as mediators between carboxylic acids and amines to enable the reaction without high temperature while preserving compound integrity
2Ease of manufacture
If acid halides are generated using thionyl chloride or phosphorus pentachloride, then amine reactive acid halides are formed, but hydrochloric acid is produced which is incompatible with many synthetic strategies
Solution Approach 1:
The patent extracts or removes the harmful by-product generation step by using alternative coupling reagents that do not produce hydrochloric acid, thereby eliminating the incompatibility issue while maintaining the ability to form amine reactive intermediates
Solution Approach 2:
The patent employs disposable coupling reagents that are consumed in the reaction to form active esters or other reactive intermediates, replacing the need for acid halide generation and avoiding hydrochloric acid production entirely
3Ease of manufacture
If newer reagents like Deoxo-Fluor and DAST are used to generate acid halides, then amine reactive acid halides are formed, but the reagents are expensive, hazardous, and require chromatography purification
Solution Approach 1:
The patent uses inexpensive, consumable coupling reagents that form easily separable by-products, eliminating the need for complex chromatography purification while maintaining effectiveness in generating reactive intermediates for amide bond formation
Solution Approach 2:
The patent converts potentially problematic reaction by-products into easily removable substances through careful reagent selection, turning what would be purification challenges into simple filtration or washing steps
4Ease of manufacture
If carbodiimides like DCC are used as coupling reagents, then amide bond formation is facilitated, but epimerization occurs and benzotriazole additives have explosive properties
Solution Approach 1:
The patent employs safe, non-explosive coupling reagents that are consumed in the reaction to form amide bonds without requiring hazardous benzotriazole additives, eliminating safety concerns while maintaining ease of manufacture
Solution Approach 2:
The patent changes the chemical nature of the coupling reagents from carbodiimide-based systems to alternative chemistries that inherently suppress epimerization, thereby maintaining amide bond formation efficiency while eliminating stereochemical side reactions
5Ease of manufacture
If HOBt/HOAt-based coupling reagents like HATU are used, then active esters are formed, but guanidinium side products are generated
Solution Approach 1:
The patent removes the source of guanidinium side products by selecting coupling reagents that do not contain HOBt/HOAt moieties, thereby eliminating the formation of harmful side products while maintaining the ability to form active esters for amide bond formation
6Ease of manufacture
If phosphonium salts like BOP are used, then coupling reactions proceed, but carcinogenic and respiratory toxic HMPA is generated
Solution Approach 1:
The patent extracts or eliminates the source of toxic HMPA by using alternative coupling reagent chemistries that do not require HMPA as a solvent or additive, thereby maintaining coupling reaction efficiency while removing carcinogenic and respiratory toxic hazards
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 efficient, mild, and general methods for amide bond formation with high conversions and low epimerization, reducing by-product formation and safety concerns, making it suitable for a broad range of amide bond forming reactions.
Implementation Method 1
catalytic molecules like heterocyclic thiolamide, S-acylthiosalicylamide, disulfide, selenium-containing heterocycles, and diselenide compounds that catalyze the transformation of hydroxy group-containing compounds into amides
Implementation Method 2
Redox dehydration coupling catalysts and methods related thereto
Data Source
AI summary
This disclosure relates to synthetic coupling methods using catalytic molecules. In certain embodiments, the catalytic molecules comprise heterocyclic thiolamide, S-acylthiosalicylamide, disulfide, selenium containing heterocycle, diselenide compound, ditelluride compound or tellurium containing heterocycle. Catalytic molecules disclosed herein are useful as catalysts in the transformation of hydroxy group containing compounds to amides, esters, ketones, and other carbon to heteroatom or carbon to carbon transformations