Nintedanib Intermediate Synthesis via Azeotropic Acetic Acid Removal
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Solution Overview
Problem
Existing methods for manufacturing methyl (E)-1-acetyl-3-(methoxy(phenyl)methylene)-2-oxoindoline-6-carboxylate, an intermediate for nintedanib, face challenges such as low yields, complex multistep processes, and high costs, particularly due to the need for evaporations to dryness and the use of reagents like chloroacetic anhydride, making them unsuitable for industrial scale adaptation.
Innovation Solution
The process involves N-acetylation of methyl 2-oxoindoline-6-carboxylate with acetic anhydride in a high boiling aromatic hydrocarbon solvent, allowing for azeotropic distillation of acetic acid, which prevents decomposition of trimethyl orthobenzoate and enables direct isolation of the product without tedious evaporations or recrystallizations, simplifying the process and improving yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing methods are used for manufacturing the intermediate, then the process can be completed, but the yield is low and the process is complex with multiple isolation steps
Solution Approach 1:
The patent combines two separate reaction steps (N-acetylation and enolether formation) into a single one-pot process. The N-acetylation of methyl 2-oxoindoline-6-carboxylate with acetic anhydride is performed, followed by direct addition of trimethyl orthobenzoate to the same reaction mixture without isolation of the intermediate N-acetyl compound. This merging eliminates multiple isolation steps and significantly improves both yield and process simplicity.
Solution Approach 2:
The patent performs N-acetylation as a preliminary step that prepares the indoline derivative for the subsequent enolether formation. By completing the N-acetylation in situ before adding trimethyl orthobenzoate, the method ensures the intermediate is properly formed and ready for the next transformation, improving overall efficiency without requiring separate isolation.
2Ease of manufacture
If evaporations to dryness are performed as in existing methods, then the product can be isolated, but the process becomes tedious and unsuitable for industrial scale
Solution Approach 1:
The patent changes the physical parameters of the reaction system by conducting both reactions in a high-boiling aromatic hydrocarbon solvent (such as xylene or toluene). This solvent choice allows the reactions to proceed at elevated temperatures while enabling simple filtration for product isolation instead of time-consuming evaporations to dryness. The high boiling point solvent remains liquid during workup, facilitating easy separation of the solid product by filtration.
3Productivity
If chloroacetic anhydride is used as in WO 01/27081, then the reaction can proceed, but the costs increase and the process becomes more complex
Solution Approach 1:
The patent replaces the expensive reagent chloroacetic anhydride with cheaper, more readily available reagents: acetic anhydride for N-acetylation and trimethyl orthobenzoate for enolether formation. These conventional reagents are less costly and more stable, reducing both material costs and handling complexity while maintaining effective reaction progression through the one-pot sequence.
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 results in high yield and purity of methyl (E)-1-acetyl-3-(methoxy(phenyl)methylene)-2-oxoindoline-6-carboxylate with reduced raw material costs and operational simplicity, making it suitable for industrial scale production with only one isolation step and omitting distillations to dryness.
Implementation Method 1
reacting methyl 2-oxoindoline-6-carboxylate with acetic anhydride in a high boiling aromatic hydrocarbon solvent to produce a methyl 1-acetyl-2-oxoindoline-6-carboxylate intermediate in solution
Implementation Method 2
allowing for azeotropic distillation of acetic acid, which prevents decomposition of trimethyl orthobenzoate
Implementation Method 3
the enolether formation is carried out in a high boiling aromatic hydrocarbon solvent
Implementation Method 4
if the N-acetylation reaction and the enolether formation is carried out in a high boiling aromatic hydrocarbon solvent, which is capable of forming azeotropes with acetic acid
Data Source
AI summary
The invention discloses the preparation method of methyl (E)-1-acetyl-3-(methoxy(phenyl)methylene)-2-oxoindoline-6-carboxylatefrom methyl 2-oxoindoline-6-carboxylate using high reaction temperatures and a reaction solvent enabling azeotropic removal of acetic acid during the reaction.