DZ2002 Synthesis via L-Malic Acid and Recrystallization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for preparing 4-(6-Amino-purin-9-yl)-2(S)-hydroxy-butyric acid methyl ester (DZ2002) are costly, time-consuming, and prone to racemization due to the use of expensive starting materials and low-yield reactions, with purification by column chromatography being inefficient.
Innovation Solution
A method utilizing L-malic acid as a starting material, involving ring-closing reactions, selective protection of functional groups, reduction, esterification, nucleophilic substitution with adenine, and recrystallization for purification, which is cost-effective, scalable, and retains chiral center integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the known method using (S)-(−)-α-hydroxybutyrolactone is used, then the chiral center can be maintained, but the starting material is expensive and the reaction yield is low
Solution Approach 1:
The patent replaces expensive (S)-(−)-α-hydroxybutyrolactone with cheap L-malic acid as the starting material. Although L-malic acid has different chemical properties, it can be converted to the desired chiral intermediate through a series of reactions, achieving both cost reduction and chiral center retention.
Solution Approach 2:
The patent changes the starting material from (S)-(−)-α-hydroxybutyrolactone to L-malic acid, which alters the chemical pathway but maintains the chiral center integrity through selective protection and reduction steps. This parameter change enables cost reduction while preserving the essential chiral property.
2Ease of manufacture
If tetraisopropyl titanate is used for ring-opening, then the lactone ring can be opened, but the reaction has low yield and requires complicated post-treatment
Solution Approach 1:
The patent extracts the problematic tetraisopropyl titanate step from the synthesis sequence and replaces it with a more efficient reduction method using borane or metal hydrides. This removes the source of low yield and complicated post-treatment while maintaining the necessary ring-opening functionality.
Solution Approach 2:
The patent replaces the complex tetraisopropyl titanate system with simpler, more efficient reducing agents like borane or metal hydrides. These alternative reagents provide the same ring-opening function with higher yield and simpler workup procedures.
3Manufacturing precision
If column chromatography is used for purification, then the product can be purified, but the process is time-consuming with low productivity
Solution Approach 1:
The patent extracts and removes the time-consuming column chromatography step from the purification process. By optimizing the reaction conditions and intermediate stability, the patent achieves sufficient purity through simpler methods, eliminating the bottleneck in productivity.
Solution Approach 2:
The patent changes the purification approach by optimizing reaction parameters to achieve better intermediate stability and selectivity. This allows for simpler purification methods that maintain high product purity while significantly reducing the time required compared to column chromatography.
4Productivity
If the chiral center is exposed during reaction, then the reaction can proceed, but racemization occurs
Solution Approach 1:
The patent applies preliminary protection of the chiral center before performing reactions that could cause racemization. By protecting the chiral center in advance, the patent allows subsequent reactions to proceed efficiently without compromising chiral integrity, thus resolving the contradiction between reaction rate and chiral stability.
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 significantly reduces costs, enhances productivity, and improves product quality by using easily available materials, minimizing racemization, and simplifying the purification process through recrystallization, resulting in a high-purity DZ2002 with controlled specific rotation.
Implementation Method 1
A ring-closing reaction was carried out by a nucleophilic substitution between L-malic acid and a protective agent
Implementation Method 2
The intermediate I obtained from step (1) was reduced to an intermediate alcohol II by a reducing agent
Implementation Method 3
The intermediate alcohol II obtained from step (2) may be esterified by an acyl chloride selected from the group consisting of p-toluenesulfochloride, mesyl chloride, trifluoro-acetyl chloride, trichloro-acetyl chloride and acetyl chloride
Implementation Method 4
The intermediate III obtained from step (3) was nucleophilically substituted by adenine in an appropriate solvent at a suitable temperature in the presence of a base and a phase transfer catalyst
Implementation Method 5
The resultant crude DZ2002 from the above methods may be purified by recrystallization
Data Source
AI summary
The present invention discloses a novel method for preparing and purifying 4-(6-Amino-purin-9-yl)-2(S)-hydroxy-butyric acid methyl ester. The preparation started from cheap and easily available L-malic acid, which was transformed to intermediate I after simultaneous protection of the groups of 1-carboxyl and 2-hydroxyl. The intermediate I was selectively reduced to intermediate alcohol II, whose hydroxyl group was further transformed to an easily leaving group to afford intermediate III. The intermediate III was nucleophilically substituted with adenine to afford intermediate IV. The intermediate IV was deprotected and methyl-esterified simultaneously in methanol in the presence of an acid or a base to afford crude 4-(6-Amino-purin-9-yl)-2(S)-hydroxy-butyric acid methyl ester, which was purified by recrystallization to afford the purified product. Comparing with the prior preparation methods, the present method has advantages in low cost, mild conditions, high retention of the chiral center during the reaction, high productivity, great improvement in the quality and yield of the product and great decrease in cost, and thus is suitable for the production on a large scale.