Antiviral Nucleotide Analog Preparation via Crystallization-Induced Resolution
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Solution Overview
Problem
Current methods for preparing compounds 12, 13, and 16 are inefficient, requiring low yields, being complex, and using costly or toxic reagents, with a need for improved methods to achieve high diastereomeric purity.
Innovation Solution
The method involves crystallization-induced dynamic resolution and treatment with specific reagents like triphenylphosphite and thionyl chloride to achieve high diastereomeric purity in compounds 12, 13, and 16, using solvents and bases such as acetonitrile and DBU to selectively crystallize and epimerize the phosphorus center.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If current methods are used to prepare compounds 12, 13, and 16, then the preparation process can be performed, but the yields are low and the process is inefficient
Solution Approach 1:
The patent employs crystallization-induced dynamic resolution which involves changing physical parameters (temperature, solvent conditions) to achieve selective crystallization of diastereomers. This transforms the preparation process from a simple reaction to a controlled crystallization process, dramatically improving both yield and efficiency by selectively isolating the desired compound 16 from the diastereomeric mixture
Solution Approach 2:
The method uses a composite approach combining chemical reaction with physical crystallization separation. By integrating the resolution step into the crystallization process rather than requiring separate purification steps, the patent achieves higher productivity and reduces material loss through a streamlined composite process
2Manufacturing precision
If current methods are used to prepare compounds 12, 13, and 16, then the preparation can proceed, but the diastereomeric purity is insufficient
Solution Approach 1:
The patent utilizes phase transition during crystallization to achieve diastereomeric separation. By controlling the phase transition from dissolved state to crystalline state under specific conditions, the desired diastereomer (compound 16) selectively crystallizes with high purity (at least 90%), simplifying the manufacturing process while achieving high manufacturing precision
Solution Approach 2:
The crystallization process acts as an intermediary mechanism that separates diastereomers based on their different crystallization behaviors. This intermediary step naturally enriches the desired compound 16 in the crystalline phase while leaving impurities in the mother liquor, achieving high purity without complex additional purification steps
3Ease of manufacture
If current methods are used to prepare compounds 12, 13, and 16, then the synthesis can be completed, but costly or toxic reagents are required
Solution Approach 1:
The patent replaces expensive and potentially toxic reagents with more economical alternatives that achieve the same or better results. The crystallization-induced dynamic resolution method uses simple, inexpensive solvents and conditions rather than requiring costly chiral reagents or complex catalysts, reducing both cost and toxicity while maintaining process reliability
Solution Approach 2:
The crystallization process is self-selective, automatically enriching the desired diastereomer without requiring additional chiral auxiliaries or catalysts. The system uses its own physical properties (different solubility and crystallization behavior of diastereomers) to achieve separation, eliminating the need for external costly or toxic chiral reagents while maintaining high reliability
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 compounds with at least 90% diastereomeric purity, improving yield and simplifying the process while reducing the use of costly or toxic reagents, leading to higher purity and efficiency in preparing these compounds.
Implementation Method 1
subjecting a solution comprising: a) a suitable solvent; b) a suitable base; c) the diastereomeric mixture 9-{(R)-2-[((R,S)-{[(S)-1-(isopropoxycarbonyl)ethyl]amino}phenoxyphosphinyl)methoxy]propyl}adenine; and, optionally, d) one or more seed crystals of 9-{(R)-2-[((S)-{[(S)-1-(isopropoxycarbonyl)ethyl]amino}phenoxyphosphinyl)methoxy]propyl}adenine, to conditions that provide for the selective crystallization of 9-{(R)-2-[((S)-{[(S)-1-(isopropoxycarbonyl)ethyl]amino}phenoxyphosphinyl)methoxy]propyl}adenine
Implementation Method 2
subjecting a solution comprising: a) a suitable solvent; b) a suitable base; c) the diastereomeric mixture 9-{(R)-2-[((R,S)-{[(S)-1-(isopropoxycarbonyl)ethyl]amino}phenoxyphosphinyl)methoxy]propyl}adenine; and, optionally, d) one or more seed crystals of 9-{(R)-2-[((S)-{[(S)-1-(isopropoxycarbonyl)ethyl]amino}phenoxyphosphinyl)methoxy]propyl}adenine, to conditions that provide for the epimerization of the phosphorus center
Data Source
AI summary
Methods for isolating 9-{(R)-2-[((S)-{[(S)-1-(isopropoxycarbonyl)ethyl]amino}phenoxyphosphinyl)methoxy]propyl}adenine (compound 16): a method for preparing, in high diastereomeric purity, intermediate compounds 13 and 15: and a method for preparing intermediate compound 12: 9-{(R)-2-[((S)-{[(S)-1-(isopropoxycarbonyl)ethyl]amino}phenoxyphosphinyl)methoxy]propyl}adenine has anti-viral properties.