Travoprost Esterification Using Non-Toxic Activating Agents
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Solution Overview
Problem
Existing methods for preparing travoprost, a prostaglandin derivative used in treating glaucoma, involve toxic alkyl halogenides or sulfates, posing safety and environmental risks due to their use as ester-forming agents.
Innovation Solution
The process involves activating travoprost acid with 2-chloro-1,3-dimethylimidazolinium chloride, isopropyl alcohol, or alkyl haloformates/dicarbonates in the presence of water-free magnesium salts, using non-toxic reagents and solvents like isopropyl alcohol or acetonitrile to form the ester, thereby avoiding toxic alkyl halogenides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If toxic alkyl halogenides or alkyl sulfates are used as ester-forming agents, then the esterification reaction proceeds efficiently, but safety and environmental risks increase due to toxicity
Solution Approach 1:
The patent introduces an intermediary coupling agent (2-chloro-1,3-dimethylimidazolinium chloride or carbonyl diimidazole) that mediates the esterification reaction between travoprost acid and isopropyl alcohol. This intermediary activates the carboxylic acid to form a reactive intermediate that can be attacked by the alcohol, achieving efficient esterification without requiring toxic alkyl halogenides or sulfates as direct reagents.
2Productivity
If strong bases like cesium carbonate are used to promote the reaction, then the esterification proceeds through the cesium salt, but the process complexity and cost increase
Solution Approach 1:
The coupling agent acts as a mediator that enables the reaction to proceed under milder conditions. By forming a reactive intermediate with the carboxylic acid, the coupling agent eliminates the need for strong bases like cesium carbonate to activate the acid, thereby simplifying the overall process while maintaining high reaction efficiency.
3Productivity
If dimethyl formamide is used as solvent, then the reaction proceeds well, but the process becomes less environmentally friendly due to solvent toxicity
Solution Approach 1:
The patent changes the solvent parameter from toxic dimethyl formamide to more environmentally friendly alternatives such as dichloromethane, chloroform, or ethyl acetate. This parameter change maintains adequate reaction efficiency while significantly reducing the environmental and health hazards associated with the solvent system.
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 method achieves high yields of travoprost with minimal side reactions and eliminates the use of toxic reagents, providing a safer and more environmentally friendly synthesis route.
Implementation Method 1
the free acid ('travoprost acid') of formula (II) is a.) activated with 2-chloro-1,3-dimethylimidazolinium chloride (DMC) and the resulting activated carboxylic acid intermediate is reacted with isopropyl alcohol
Implementation Method 2
b.) activated with a straight or branched C 1-6 alkyl haloformate and the resulting mixed anhydride is reacted with isopropyl alcohol
Implementation Method 3
activated with a straight or branched C 1-8 dialkyl dicarbonate and reacted with isopropyl alcohol in the presence of water-free magnesium salt
Implementation Method 4
Activation of the alcohol component may be carried out with metal alcoholates, as for metal alcoholate for example potassium tertiary-butoxide may be used
Data Source
AI summary
The subject of the invention is process the preparation of travoprost of formula (I) characterized by that the free acid of formula (II) is a. ) activated with 2-chloro-l,3-dimethylimidazolinium chloride (DMC) and the resulting activated carboxylic acid intermediate is reacted with isopropyl alcohol, or b. ) reacted with alkyl haloformate and the resulting mixed anhydride is reacted with isopropyl alcohol, or c. ) activated with a straight or branched C1-8 dialkyl dicarbonate and reacted with isopropanol in the presence of water-free magnesium salt.