Quinazoline Synthesis via Segmentation and Parameter Changes
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Solution Overview
Problem
Current methods for synthesizing aminocrotonylamino-substituted quinazoline derivatives are not suitable for industrial scale due to low yields, laborious purification processes, and the use of expensive or difficult-to-obtain starting materials, along with safety concerns and heavy metal contamination issues.
Innovation Solution
A process involving the reaction of 7-chloro-6-nitro-3H-quinazolin-4-one with a primary amine in the presence of POCl3, followed by sulphonyl derivative formation, reduction, and a Wittig-Horner-Emmons reaction with a hydrogen sulphite adduct, using easily obtainable and high-purity starting materials to produce aminocrotonylamino-substituted quinazoline derivatives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the one-pot reaction method from WO 2002/50043 is used to prepare aminocrotonylamino-substituted quinazolines, then the synthesis can be completed in a single reaction vessel, but the yield is at most 50% and laborious purification by column chromatography is needed
Solution Approach 1:
The patent divides the synthesis into multiple discrete steps: Step 1 forms the quinazoline core structure, Step 2 introduces the aminocrotonylamino substituent, and Step 3 performs purification. This segmentation allows each step to be optimized independently, achieving higher overall yields (7-47% combined) compared to the one-pot method, while eliminating the need for laborious column chromatography through crystallization-based purification.
2Ease of manufacture
If bromocrotonic acid is used as starting material according to WO 2002/50043, then the reaction can proceed, but the educt is not commercially available in large amounts and the corresponding methyl bromocrotonate is only available with a purity of about 80%
Solution Approach 1:
The patent performs preliminary purification of methyl bromocrotonate through crystallization before using it in the main reaction sequence. This preliminary action removes impurities from the commercially available 80% pure material, ensuring high purity starting materials for subsequent steps without requiring expensive specialized suppliers.
Solution Approach 2:
The patent uses commercially available methyl bromocrotonate (even at 80% purity) as a disposable starting material that can be easily purified through simple crystallization, rather than requiring expensive, high-purity, specially-sourced bromocrotonic acid. This approach prioritizes ease of acquisition and simple purification over initial purity.
3Manufacturing precision
If the process from WO 2005/037824 is used with thionyl chloride in Step (c), then the chlorination can be achieved, but the use of thionyl chloride is problematic for safety reasons
Solution Approach 1:
The patent changes the chemical parameters of the chlorination step by replacing thionyl chloride with phosphorus oxychloride (POCl3) as the chlorinating agent. This parameter change maintains the desired regioselective chlorination at the 7-position of the quinazolinone ring while eliminating the safety hazards associated with thionyl chloride handling and use.
4Manufacturing precision
If cyclic or heterocyclic alcohols are used to introduce group R d in excess of about 2 equivalents according to step (e), then the substitution reaction can proceed, but these starting materials are difficult to obtain or expensive and phase transfer catalysis is needed
Solution Approach 1:
The patent uses phase transfer catalysts (such as 18-crown-6 or tetrabutylammonium bromide) as intermediaries to facilitate the nucleophilic substitution reaction between the chloroquinazoline and cyclic/heterocyclic alcohols. This intermediary enables the reaction to proceed efficiently with only 1.1-1.5 equivalents of alcohol, reducing both cost and improving availability compared to using 2+ equivalents without phase transfer catalysis.
Solution Approach 2:
The patent optimizes the stoichiometry parameter by reducing the alcohol equivalent from 2+ to 1.1-1.5 equivalents, and changes the reaction conditions parameter by introducing phase transfer catalysts and using acetonitrile as solvent. These parameter changes together improve both the efficiency of substitution and the cost-effectiveness of starting materials.
5Manufacturing precision
If hydrogenation is carried out with the addition of acetic acid to prevent dechlorinated by-products, then the chlorine atom is protected, but traces of nickel catalyst are dissolved and entrained into the final step causing heavy metal contamination
Solution Approach 1:
The patent extracts or removes the problematic element (acetic acid) from the hydrogenation step by replacing it with alternative acids such as formic acid or hydrochloric acid. This taking out action eliminates the heavy metal nickel contamination that occurs when acetic acid is used, while still preventing dechlorinated by-products through the alternative acid additives.
Solution Approach 2:
The patent uses disposable, easily removable acid additives (formic acid or hydrochloric acid) in place of acetic acid during hydrogenation. These alternative acids achieve the protective function against dechlorination without causing persistent heavy metal contamination, and can be easily removed in subsequent workup steps.
6Manufacturing precision
If the existing multi-step process is used with low throughput reactions, then each partial reaction can be completed, but the throughput in step (e) is only 1/60 (1kg of starting material require a reactor volume of 60 I)
Solution Approach 1:
The patent changes the physical parameters of step (e) by using acetonitrile as solvent instead of traditional solvents, and by optimizing the base equivalents and temperature conditions. These parameter changes increase the throughput from 1/60 to significantly higher values, allowing 1kg of starting material to be processed in much smaller reactor volumes while still achieving complete nucleophilic substitution.
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 enhances yield, reduces purification complexity, eliminates safety hazards, and uses cost-effective materials, making it suitable for industrial-scale production while avoiding heavy metal contamination.
Implementation Method 1
reacting 7-chloro-6-nitro-3H-quinazolin-4-one with a primary amine of formula R a -NH 2 (XV) in the presence of POCl 3
Implementation Method 2
converting the resulting compound of general formula (X) into the sulphonyl derivative of formula (XIII) by reacting with an alcohol of formula R d -OH (XVI) in the presence of a base
Implementation Method 3
reducing the compound of formulae (XIII) thus obtained to the amino derivative of formula (XIV)
Implementation Method 4
converting the amino derivatives of formula (XIV) into the phosphonic ester of formula (III) by reacting with a di-(C 1-4 -alkyl)-phosphonoacetic acid
Implementation Method 5
a Wittig-Horner-Emmons reaction of dialkyl-phosphonoacetamido-substituted quinazolines (III) with a 2-aminoacetaldehyde (IV)
Data Source
AI summary
The invention relates to an improved process for preparing aminocrotonylamino-substituted quinazoline derivatives of general formula (I) wherein the groups Ra, Rb, Rc and Rd have the meanings given in the claims, as well as sulphonyl derivatives of formula (XIII) and the use thereof as synthesis components for preparing quinazolines of formula (I). The quinazoline derivatives of formula (I) are inhibitors of signal transduction mediated by tyrosinekinases and by the Epidermal Growth Factor-Receptor (EGF-R) and are therefore particularly suitable for the treatment of tumoral diseases.