Tenofovir Alafenamide Preparation via Crystallization-Induced Dynamic Resolution
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Solution Overview
Problem
Current methods for preparing diastereomerically pure Tenofovir Alafenamide suffer from inefficiencies such as significant mass loss, laboriousness, and limited diastereomeric enrichment, particularly in the formation of diastereoisomeric salts and the use of stereospecific reactions.
Innovation Solution
A new synthetic strategy involving the use of diastereoisomerically pure phosphoramidate precursors, where a mixture of diastereoisomers crystallizes under specific reaction conditions to enrich the R p diastereomer, followed by crystallization-induced dynamic resolution in a mixed solvent system, allowing for efficient enrichment and isolation of the desired diastereomer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If diastereoisomeric salts are formed and separated by crystallization, then diastereomeric purity is improved, but mass loss increases and process complexity increases
Solution Approach 1:
The invention performs preliminary enrichment of the desired Rp diastereomer during the chlorination reaction itself by controlling reaction conditions (solvent system, temperature, additives) to favor formation of the Rp diastereoisomeric chloride. This preliminary enrichment reduces the burden on subsequent separation steps and minimizes mass loss compared to forming and separating diastereoisomeric salts.
Solution Approach 2:
The invention changes physical and chemical parameters of the reaction system including solvent composition (mixed solvent system with specific polarity), temperature, and addition of catalysts or additives to control the stereoselectivity of the chlorination reaction. These parameter changes enable preferential formation of the Rp diastereomer directly in the reaction mixture, avoiding the need for salt formation and crystallization.
2Manufacturing precision
If diastereoisomeric salts are formed and separated by crystallization, then diastereomeric purity is improved, but process time and labor increase
Solution Approach 1:
The invention performs preliminary enrichment of the desired Rp diastereomer during the chlorination reaction itself by controlling reaction conditions (solvent system, temperature, additives) to favor formation of the Rp diastereoisomeric chloride. This preliminary enrichment reduces the burden on subsequent separation steps and minimizes mass loss compared to forming and separating diastereoisomeric salts.
Solution Approach 2:
The invention changes physical and chemical parameters of the reaction system including solvent composition (mixed solvent system with specific polarity), temperature, and addition of catalysts or additives to control the stereoselectivity of the chlorination reaction. These parameter changes enable preferential formation of the Rp diastereomer directly in the reaction mixture, avoiding the need for salt formation and crystallization.
3Manufacturing precision
If stereospecific SN2 reaction is used, then diastereomeric purity is improved, but the requirement for diastereomerically pure intermediate increases process complexity
Solution Approach 1:
The invention performs preliminary enrichment of the desired Rp diastereomer during the chlorination reaction itself by controlling reaction conditions (solvent system, temperature, additives) to favor formation of the Rp diastereoisomeric chloride. This preliminary enrichment reduces the burden on subsequent separation steps and minimizes mass loss compared to forming and separating diastereoisomeric salts.
Solution Approach 2:
The invention changes physical and chemical parameters of the reaction system including solvent composition (mixed solvent system with specific polarity), temperature, and addition of catalysts or additives to control the stereoselectivity of the chlorination reaction. These parameter changes enable preferential formation of the Rp diastereomer directly in the reaction mixture, avoiding the need for salt formation and crystallization.
4Manufacturing precision
If CIDR is used to enrich desired isomer, then diastereomeric enrichment is improved, but maximum enrichment is limited to approximately 85%
Solution Approach 1:
The invention changes physical and chemical parameters of the reaction system including solvent composition (mixed solvent system with specific polarity), temperature, and addition of catalysts or additives to control the stereoselectivity of the chlorination reaction. These parameter changes enable preferential formation of the Rp diastereomer directly in the reaction mixture, achieving greater than 85% diastereomeric enrichment.
Solution Approach 2:
The invention uses a mixed solvent system combining solvents with different polarities and properties to create an optimized reaction environment that enhances stereoselectivity. This composite solvent system, along with catalysts or additives, enables greater diastereomeric enrichment compared to single solvent systems or standard CIDR conditions.
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 diastereomeric purity and yield of Tenofovir Alafenamide, with improved chemical and optical purity, reducing the need for extensive purification steps and enhancing the efficiency of the production process.
Implementation Method 1
a mixture of diastereoisomers crystallizes under specific reaction conditions to enrich the R p diastereomer
Implementation Method 2
crystallization-induced dynamic resolution in a mixed solvent system, allowing for efficient enrichment and isolation of the desired diastereomer
Data Source
AI summary
The invention relates to an efficient preparation method of diastereomerically pure Tenofovir Alafenamide (TA) of structure la with the absolute configuration (S) at the phosphorus atom - S p-diastereoisomer. Tenofovir Alafenamide Fumarate of formula 2 (TAF) is a reverse transcriptase inhibitor, which is currently in the clinical study stage as a prodrug of Tenofovir 3 for the treatment of HIV infection and hepatitis B. Compared to the hitherto used prodrug, Tenofovir disoproxil fumarate of formula 4, TAF exhibits greater antiviral activity and better distribution in the lymphatic system.