Nitrilase Mutant Hydrolysis for Brivaracetam Chiral Intermediate Synthesis
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Solution Overview
Problem
Existing synthetic routes for brivaracetam chiral intermediates, such as compound (IV), face challenges with complex processes, low resolution yields, and isomerization impurities, making them unsuitable for industrial production.
Innovation Solution
An enzymatic synthesis method using a nitrilase mutant to catalyze the hydrolysis of 3-cyanohexanitrile to produce (R)-3-cyanohexanoic acid, followed by hydrogenation to form (R)-3-aminomethyl hexanoic acid, employing recombinant strains with specific amino acid mutations at positions 140 and 175.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chiral resolution with phenylethylamine and Huffman degradation are used to synthesize compound (IV), then the chiral intermediate can be obtained, but the process becomes complex and resolution yield decreases
Solution Approach 1:
The patent replaces traditional chemical resolution methods (mechanical/chemical system) with enzymatic resolution using nitrilase. The nitrilase enzyme catalyzes the hydrolysis of nitrile to carboxylic acid with high stereoselectivity, eliminating the need for complex chiral resolving agents and multiple degradation steps, thus simplifying the process while improving yield
Solution Approach 2:
The patent changes the reaction parameters by using enzymatic catalysis under mild conditions (aqueous buffer, 25-37°C, pH 7-8) compared to the harsh conditions required for Huffman degradation (strong bases like NaOH or KOH, high temperatures). This parameter change enables direct synthesis of the chiral intermediate without complex resolution steps
2Manufacturing precision
If transaminase catalytic reduction amination is used to prepare chiral compound (IV), then the synthesis can be achieved, but the ee value is only about 90% and process complexity increases
Solution Approach 1:
The patent replaces transaminase catalytic reduction with nitrilase-catalyzed hydrolysis. The nitrilase enzyme provides higher stereoselectivity (ee > 98%) for the hydrolysis of (R)-3-cyanohexanoic acid, eliminating the need for complex transamination steps and achieving superior enantiomeric purity in a simpler process
Solution Approach 2:
The patent extracts and utilizes the specific stereoselective activity of nitrilase enzyme to directly produce the desired (R)-enantiomer with high ee value, separating the useful stereoselective hydrolysis function from the complex multi-step transamination process
3Productivity
If traditional synthetic routes are used for brivaracetam intermediates, then the production can proceed, but isomerization impurities are generated and resolution yield is low
Solution Approach 1:
The patent replaces traditional chemical synthesis methods that cause isomerization with enzymatic hydrolysis using nitrilase. The enzyme operates under mild conditions (physiological pH and temperature) that prevent isomerization of the chiral center, eliminating impurity formation while maintaining high productivity
Solution Approach 2:
The patent creates an inert enzymatic environment (aqueous buffer solution at pH 7-8 and 25-37°C) that protects the chiral substrate from isomerization, similar to how an inert atmosphere protects against unwanted reactions. This benign enzymatic environment prevents harmful side reactions while enabling high-yield production
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 method achieves a high conversion rate and enantiomeric excess of 98% for (R)-3-cyanohexanoic acid and a yield of over 85% for (R)-3-aminomethyl hexanoic acid, providing a short, mild reaction route suitable for industrial synthesis.
Implementation Method 1
synthesizing (R)-3-cyanohexanoic acid by using an enzyme having nitrilase activity to catalyze hydrolysis of 3-cyanohexanenitrile
Implementation Method 2
stereoselective hydrolysis of 3-cyanohexanoic acid (V), and then subjecting (R)-3-cyanohexanoic acid (V) to hydrogenation reduction
Implementation Method 3
subjecting (R)-3-cyanohexanoic acid (V) to hydrogenation reduction to synthesize (R)-3-aminomethyl hexanoic acid (IV)
Data Source
AI summary
A method for synthesizing a brivaracetam chiral intermediate (R)-3-cyanohexanoic acid by catalyzing the hydrolysis of 3-cyanohexanitile using an enzyme with nitile hydrolysis activity, and the enzyme with nitrile hydrolysis activity is obtained by carrying out a single mutation or a double mutation on an amino acid at position 140 or an amino acid at position 175 in an amino acid sequence as set forth in SEQ ID NO.2. Compared with a wild type, the nitrilase mutant has the activity increased by 10 times, an ee value increased to 300 or more from 39, a substrate conversion rate of 45%, and a product ee which can reach 98.5%, and the yield of (R)-3-aminomethyl-hexanoic acid by catalytic hydrogenation synthesis using (R)-3-cyanohexanoic acid reaches 85% or more. This features a short synthesis route, mild reaction conditions, and high atom economy, and can be applied to the industrial synthesis of the brivaracetam intermediate.