Rilpivirine Synthesis via Segmented Intermediates
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Solution Overview
Problem
Current processes for preparing rilpivirine, a second-generation NNRTI for HIV treatment, are complex, resource-intensive, and not well-suited for industrial scale production, lacking efficient methods for key intermediates like 4-(4-chloropyrimidin-2-ylamino)benzonitrile and 4-iodo-2,6-dimethyl benzenamine, and do not provide a suitable tosylate salt form.
Innovation Solution
A novel process involving condensation reactions with specific solvents and reagents to produce 4-(4-chloropyrimidin-2-ylamino)benzonitrile, followed by conversion to rilpivirine using (E)-3-(4-amino-3,5-dimethylphenyl)acrylonitrile hydrochloride, and the formation of a tosylate salt of rilpivirine, which is simpler, eco-friendly, and scalable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional processes are used for preparing rilpivirine, then the drug can be synthesized, but the process is complex and resource-intensive
Solution Approach 1:
The synthesis process is divided into distinct modular stages: preparation of 4-iodo-2,6-dimethylbenzenamine, synthesis of (E)-3-(4-amino-3,5-dimethylphenyl)acrylonitrile hydrochloride, preparation of 4-(4-chloropyrimidin-2-ylamino)benzonitrile, and final coupling to form rilpivirine. Each stage can be independently optimized and scaled, reducing overall process complexity while maintaining manufacturability.
Solution Approach 2:
Key intermediates such as 4-iodo-2,6-dimethylbenzenamine and 4-(4-chloropyrimidin-2-ylamino)benzonitrile are prepared in advance through optimized preliminary steps. The iodination step uses iodine and base to pre-form the aryl iodide, which then serves as a ready substrate for subsequent palladium-catalyzed coupling reactions, streamlining the overall synthesis.
2Productivity
If conventional processes are used for preparing rilpivirine, then the drug can be synthesized, but it is not well-suited for industrial scale production
Solution Approach 1:
The synthesis conditions are optimized for industrial scale by adjusting parameters such as solvent selection (using ethyl acetate and isopropyl alcohol instead of less scalable solvents), temperature profiles (reflux conditions followed by controlled cooling), and stoichiometry. The use of common industrial solvents and standard purification techniques enhances scalability.
Solution Approach 2:
The process employs readily available, inexpensive reagents and catalysts that can be easily sourced at industrial scale. The palladium catalyst system uses commercially available complexes that are effective at low loadings, and the reagents such as iodine, phosphines, and bases are standard industrial chemicals with established supply chains.
3Manufacturing precision
If conventional processes are used, then rilpivirine can be prepared, but efficient methods for key intermediates are lacking
Solution Approach 1:
The patent introduces specific intermediary compounds with optimized structures for subsequent reactions. The 4-iodo-2,6-dimethylbenzenamine intermediate is specifically designed to undergo efficient palladium-catalyzed cross-coupling, and the 4-(4-chloropyrimidin-2-ylamino)benzonitrile intermediate is prepared through optimized condensation reactions that ensure high purity and yield for the final coupling step.
Solution Approach 2:
Traditional mechanical mixing and purification methods are replaced with more efficient chemical approaches. The use of palladium-catalyzed coupling reactions replaces multi-step organic synthesis sequences, and the purification process uses selective precipitation and filtration instead of extensive chromatography, significantly improving intermediate preparation efficiency.
4Adaptability or versatility
If conventional processes are used, then rilpivirine can be synthesized, but a suitable tosylate salt form is not provided
Solution Approach 1:
The patent provides multiple salt forms of rilpivirine including the tosylate salt, hydrochloride salt, and fumarate salt, each with distinct pharmaceutical properties. The tosylate salt form is specifically optimized for improved solubility and stability characteristics, providing versatility in formulation options while using a straightforward salt formation process that does not add significant complexity.
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 new process is reproducible, cost-effective, and suitable for industrial production, providing a robust method for rilpivirine synthesis and its tosylate salt, enhancing the pharmaceutical composition's efficacy and stability.
Implementation Method 1
condensing the 2-chloro-4-methoxypyrimidine with 4-aminobenzonitrile in the presence of p-toluene sulfonic acid
Implementation Method 2
reacting the 4-(4-methoxypyrimidin-2-ylamino)benzonitrile with pyridine hydrochloride to obtain 4-(4-hydroxypyrimidin-2-ylamino)benzonitrile
Implementation Method 3
reacting the 4-(4-hydroxypyrimidin-2-ylamino)benzonitrile with phosphorous oxychloride to obtain a compound of formula I
Implementation Method 4
reacting the 4-(4-chloropyrimidin-2-ylamino)benzonitrile with (E)-3-(4-amino-3,5-dimethylphenyl)acrylonitrile hydrochloride
Implementation Method 5
adding p-toluene sulfonic acid to the solution obtained in step (a)
Data Source
AI summary
The present invention provides a novel process for the preparation of 4-(4-hydroxypyrimidin-2-ylamino)benzonitrile. The present invention also provides a novel process for the preparation of 4-iodo-2,6-dimethyl benzenamine. The present invention further provides an improved process for the preparation of rilpivirine. The present invention further provides a tosylate salt of rilpivirine, process for its preparation and pharmaceutical compositions comprising it.