Fluralaner Synthesis Sequence to Limit Dimeric Impurities

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Solution Overview

Problem

Existing processes for synthesizing Fluralaner suffer from low yields and high impurity formation, particularly the dimeric impurity, making them inefficient and laborious for industrial production.

Innovation Solution

A modified reaction sequence is employed where specific reagents are added in a defined order to minimize side reactions, specifically by stirring the initial composition with 2,2,2-trifluoroethylamine and a catalyst before adding the carboxylic acid activating agent, thereby reducing the formation of dimeric impurities and enhancing the yield and purity of Fluralaner.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the conventional synthesis process is used, then the reaction can proceed, but the yield is low (around 41%) and dimeric impurities form

Engineering Contradiction:

ImproveyieldVSAvoiddimeric impurity formation

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The amine is added to the reaction mixture before the carboxylic acid activating agent. This preliminary action ensures that the amine is already present and ready to react when the activated acid intermediate is formed, preventing the acid intermediate from undergoing unwanted condensation reactions that lead to dimeric impurities. The amine acts as a pre-positioned reactant that captures the activated acid intermediate before it can form dimers.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

By adding the amine first, the process creates a preliminary protective effect against dimer formation. The amine is positioned in advance to counteract the potential harmful side reaction between carboxylic acid intermediates. When the activating agent is subsequently added, the amine is already in place to immediately react with the activated acid, preventing the acid from reacting with itself to form dimers.

Inventive Principle:

Principle #9Preliminary anti-action

2Manufacturing precision

If complex purification steps are employed to remove impurities, then product purity increases, but the process becomes more laborious and time-consuming

Engineering Contradiction:

Improveproduct purityVSAvoidpurification process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention converts the potential harm of side reactions into a benefit by controlling the reaction sequence. By adding the amine first, the process ensures that even if some dimerization occurs initially, the subsequent addition of the activating agent followed by amine leads to predominant formation of the desired product. The reaction conditions are designed so that the main reaction pathway overrides any initial side reactions, effectively converting the potential problem of impurity formation into a process that naturally favors product formation.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Loss of time

If the reaction is run to completion with conventional methods, then the reaction finishes, but extensive purification is required due to impurity formation

Engineering Contradiction:

Improvepurification timeVSAvoidimpurity formation

Core Design Contradiction:

Loss of timeVSObject-generated harmful factors

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The reaction sequence maintains continuous useful action by ensuring that the amine is present throughout the critical phase of activated acid formation. Rather than adding reagents in separate stages with idle periods, the amine is already in place when the activating agent is added, creating a continuous reactive environment where the desired product formation is favored throughout the reaction process, minimizing windows for side reactions.

Inventive Principle:

Principle #20Continuity of useful action

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 process achieves yields of over 70% with a purity of more than 98%, significantly reducing the need for complex purification steps and making it suitable for industrial-scale production.

Implementation Method 1

mediated by PPh3 and I2

Methodology Applied

Scientific EffectCatalysis: Catalysis

Implementation Method 2

carboxylic acid activating agent, preferably a carbodiimide

Methodology Applied

Scientific EffectChemical Bonding: Chemical Bonding

Data Source

PatentEP4077285B1Process for preparing fluralaner

Publication Date: 2025.12.31 KRKA D D NOVO MESTO

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AI summary

The invention relates to an improved process for the synthesis of Fluralaner in an efficient and economical way.