Substituted 4-amino-pyrimidine Synthesis via Cyclization
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Solution Overview
Problem
Current methods for synthesizing 4-amino-5-aminomethyl-2-methylpyrimidine, a key intermediate in vitamin B1 production, face challenges such as low yields, use of toxic reagents, and complex multi-step processes, making them economically unattractive and environmentally hazardous.
Innovation Solution
A new process involving the cyclization reaction of N-substituted N-(3-amino-2-cyanoallyl)amines with alkylnitriles, specifically using a base to form a compound of formula IV, which allows for improved yield and avoids the use of highly toxic reagents like o-chloroaniline, optimizing reaction conditions to enhance efficiency and purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional multi-step synthesis procedures are used (e.g., UBE-Takeda procedure, BASF procedure), then the synthesis of 4-amino-5-aminomethyl-2-methylpyrimidine can be achieved, but the process complexity increases and requires multiple reaction steps with additional purification and safety measures
Solution Approach 1:
The patent combines multiple reaction steps into a single cyclization reaction. The new method directly cyclizes N-substituted N-(3-amino-2-cyanoallyl)amines with alkylnitriles in one step to form the pyrimidine ring, eliminating the need for separate steps to form intermediates like cyanoacetaldehyde dimethyl acetal or enamine derivatives, thus reducing process complexity while maintaining synthesis feasibility
Solution Approach 2:
The patent uses pre-formed N-substituted N-(3-amino-2-cyanoallyl)amines as starting materials that already contain the necessary functional groups arranged for direct cyclization. This preliminary preparation of the cyanoallylamine structure enables the direct one-step cyclization with nitriles, avoiding the need for in-situ generation of reactive intermediates and reducing overall process complexity
2Productivity
If toxic reagents like o-chloroaniline are used in the synthesis process, then the cyclization reaction can proceed, but harmful factors increase due to carcinogenicity and environmental hazards
Solution Approach 1:
The patent replaces expensive and toxic o-chloroaniline with cheaper, non-toxic alternatives such as ammonia, primary amines, or secondary amines. These simpler amine reagents achieve the same cyclization function without the carcinogenic properties of o-chloroaniline, eliminating harmful factors while maintaining reaction efficiency
Solution Approach 2:
The patent eliminates the need to handle and dispose of toxic o-chloroaniline by using benign amine reagents. This conversion transforms a harmful process into a safe one, where the amine reagents can be used in excess and easily removed without special safety measures, converting a hazardous operation into a safe and simple process
3Reliability
If acetamidine hydrochloride is used as starting material in the UBE-approach, then the synthesis can proceed, but the cost increases due to the expense of acetamidine hydrochloride and the need to use two equivalents
Solution Approach 1:
The patent replaces expensive acetamidine hydrochloride with much cheaper amine reagents such as ammonia, primary amines, or secondary amines. These inexpensive reagents perform the same function of providing the amino group and enabling cyclization, dramatically reducing material cost while maintaining synthesis feasibility
Solution Approach 2:
The patent changes the chemical nature of the starting material from acetamidine hydrochloride (a protected amidine) to simple amines or ammonia. This parameter change in the starting material structure allows for cheaper reagents and eliminates the need for deprotection steps, reducing both material cost and process complexity
4Productivity
If o-chloroaniline is used to form enamine intermediates, then the cyclization with acetamidine can be achieved, but harmful factors increase and additional separation and reuse steps are required
Solution Approach 1:
The patent uses simple, non-toxic amine reagents that do not require recovery and reuse. These reagents can be used in catalytic or stoichiometric amounts and are easily removed from the final product without complex separation procedures, eliminating carcinogenic contamination while maintaining reaction efficiency
Solution Approach 2:
The patent eliminates the enamine intermediate step entirely by using amines that can directly participate in the cyclization reaction. This removes the need to form, use, and then separate and reuse o-chloroaniline, extracting the harmful step from the process and replacing it with a direct, clean reaction
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 process significantly improves the yield of 4-amino-5-aminomethyl-2-methylpyrimidine, making it more economically viable and environmentally friendly by reducing the need for toxic substances and simplifying the synthesis steps, while maintaining high product purity.
Implementation Method 1
a new reaction to 2-alkyl-4-amino-5-formylaminomethylpyrimidines (especially to 2-methyl-4-amino-5-formylaminomethyl-pyrimidine) by a cyclization reaction of N-substituted N-(3-amino-2-cyanoallyl)amines (especially of N-(3-amino-2-cyanoallyl)formamide) and alkylnitriles such as acetonitrile
Data Source
Figure 1(I)~1(VI)
Figure 2
AI summary
The present invention is directed to a process for the manufacture of compounds of formula IV wherein R1 is an amino protecting group, and R2 is hydrogen or C1-10 alkyl, comprising a) reacting a compound of formula Ia, wherein M+ is a cation, preferably selected from the group consisting of Li+, Na+, K+, 1/2 Mg2+ and 1/2 Zn2+, (formula 1a) with an ammonium salt NH4 +X-, wherein X- is an anion, preferably selected from the group consisting of chloride, bromide, sulfate and acetate, in a solvent to a compound of formula II b) reacting a compound of formula II with a nitrile R2-CN in the presence of a base to a compound of formula IV. The present invention is further directed to compounds of formula II and their use for the manufacture of vitamin B1.