Dolasetron Synthesis Eliminating Protective Groups
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Solution Overview
Problem
Current methods for producing Dolasetron at an industrial scale are inefficient due to the use of protective groups leading to diastereoisomer mixtures, requiring complex purification processes like column chromatography, and involving costly equipment and prolonged extraction times, resulting in reduced atomic efficiency and increased residues.
Innovation Solution
A method that eliminates the need for protective groups, simplifies the synthesis by reducing steps, and uses a 'one-pot' procedure with aprotic solvents, allowing for easier purification through recrystallization and minimizing solvent use, thereby reducing residues and equipment requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If protective groups are used in the synthesis of Dolasetron, then the synthesis route can be controlled, but the synthesis route lengthens and atomic efficiency is reduced
Solution Approach 1:
The patent removes the protective group (THP) from the synthesis route entirely. Instead of using THP protection and deprotection steps, the invention uses a direct esterification reaction between the alcohol and indole-3-carboxylic acid that proceeds without protective groups, thereby eliminating unnecessary steps and improving atomic efficiency while maintaining synthesis control through alternative means (e.g., reaction conditions, stoichiometry)
Solution Approach 2:
The patent implements a continuous synthesis route where the esterification reaction proceeds directly to form the target compound without interruption for protective group manipulation. The reaction continues smoothly from reactants to product in a single operational sequence, eliminating the discontinuous nature of protection-deprotection cycles and improving overall productivity
2Reliability
If THP protective group is used, then the synthesis can be protected, but a mixture of diastereoisomers is obtained instead of a single product
Solution Approach 1:
The patent eliminates the THP protective group that causes diastereoisomer formation. By using a different synthetic approach without THP protection, the reaction proceeds to give a single stereoisomer product rather than a mixture, thereby improving stereoselectivity while maintaining protection reliability through alternative mechanisms
Solution Approach 2:
The patent changes the reaction parameters and conditions to achieve high stereoselectivity without protective groups. By optimizing reaction conditions (temperature, solvent, stoichiometry, catalysts), the synthesis achieves selective formation of the desired stereoisomer directly, avoiding the need for THP protection that would otherwise be used to control stereochemistry
3Manufacturing precision
If column chromatography is used for purification, then the purification can be carried out, but the process becomes complicated and residues increase at industrial scale
Solution Approach 1:
The patent replaces expensive, complex column chromatography equipment with simpler, more suitable purification methods. The synthesis is designed to produce a product that can be purified by simpler means (such as filtration, recrystallization, or simple distillation), eliminating the need for complex chromatographic equipment and reducing residues while maintaining purification effectiveness
Solution Approach 2:
The patent changes the physical and chemical parameters of the product and process to enable simpler purification methods. By adjusting the product's physical properties (solubility, melting point, volatility) and process conditions, the synthesis becomes amenable to simple purification techniques that are scalable to industrial levels, avoiding the complexity of column chromatography
4Productivity
If the synthesis is carried out at industrial scale, then production volume increases, but handling and purification become complicated
Solution Approach 1:
The patent designs the synthesis to produce a product with properties suitable for industrial handling and purification. The product can be isolated and purified by simple, scalable methods rather than complex chromatography, making industrial-scale manufacturing feasible and practical while maintaining ease of handling and reducing purification complexity
Solution Approach 2:
The patent optimizes the physical and chemical parameters of the product to facilitate industrial-scale handling and purification. By controlling the product's physical properties (solid/liquid state, solubility, stability), the synthesis becomes suitable for large-scale production with simple purification methods, avoiding the handling and purification problems that arise at industrial scales
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 achieves higher yields with improved atomic efficiency, reduces the number of steps and residues, and eliminates the need for costly equipment, making the process more productive and environmentally friendly.
Implementation Method 1
a) Esterification of the alcohol of formula IV with indole-3-carboxylic acid (compound III) or a reactive derivative thereof
Implementation Method 2
b) Dieckmann reaction of intermediate V, by reaction with a strong organic or inorganic base, to give intermediate VI
Implementation Method 3
c) Dealcoxycarbonylation of intermediate VI to give Dolasetron base and, if required, a pharmaceutically acceptable salt thereof or hydrates or solvates of the base or of said salt
Data Source
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AI summary
The present invention relates to a method for obtaining Dolasetron that comprises: a) Esterification of the alcohol of formula (IV) with indole-3-carboxylic acid (compound (III)) or a reactive derivative thereof, to give a compound of formula (V), followed by step b) which includes Dieckmann reaction of the intermediate (V), by reaction with a strong organic or inorganic base, to give the intermediate (VI), and step c) which comprises dealcoxycarbonylation of the intermediate (VI) to give Dolasetron base and, if desired, a pharmaceutically acceptable salt thereof, hydrates or solvates of the base of said salt. The invention also relates to the intermediates (V) and (VI), and methods for obtaining them. With the method of the present invention Dolasetron is obtained at industrial scale with good yields, with decreased use of reactants and solvents, while said method is also of greater atomic efficiency.