Molnupiravir Synthesis via Tosylate Salt Purification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing synthetic routes for Molnupiravir, an antiviral agent for COVID-19, face challenges such as high costs due to the use of immobilized enzymes, low yields, formation of impurities, and the hazardous nature of formic acid used in deprotection reactions.
Innovation Solution
A novel process involving the reaction of 2',3'-O-isopropylidene cytidine sulfate with isobutyric anhydride, followed by salt formation with para-toluenesulphonic acid monohydrate to purify and deprotect, avoiding the use of formic acid and column chromatography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If formic acid is used for acetonide deprotection, then deprotection is achieved, but carbon monoxide is released creating safety hazards
Solution Approach 1:
The patent replaces formic acid (which releases harmful carbon monoxide) with hydrochloric acid in aqueous isopropyl alcohol. This substitution eliminates the harmful gas release while maintaining effective deprotection of the acetonide group, converting a harmful process into a safe one.
2Manufacturing precision
If column chromatography is used for purification, then purity is improved, but process complexity and cost increase
Solution Approach 1:
The patent employs simple filtration and washing techniques instead of expensive column chromatography. The purification is achieved through straightforward solid-liquid separation and solvent washing, eliminating the need for complex chromatographic equipment and reducing process complexity while maintaining product purity.
3Manufacturing precision
If immobilized enzymes are used for esterification, then selectivity is improved, but cost increases significantly
Solution Approach 1:
The patent replaces expensive immobilized enzyme catalysts with simple chemical reagents (isobutyric anhydride and base). This substitution dramatically reduces material costs while achieving the desired esterification reaction, making the process economically viable for large-scale production.
4Productivity
If hydroxylamination is performed on cytidine acetonide ester, then molnupiravir is formed, but ester hydrolysis occurs forming N-hydroxycytidine byproduct
Solution Approach 1:
The patent performs acetonide deprotection before hydroxylamination by treating the cytidine acetonide ester with hydrochloric acid in aqueous isopropyl alcohol. This preliminary deprotection step removes the acetonide group to give free cytidine, which then undergoes hydroxylamination without ester hydrolysis, preventing N-hydroxycytidine byproduct formation and improving overall product purity.
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 achieves higher yields and purity of Molnupiravir while eliminating the risks associated with formic acid, such as carbon monoxide release, and avoids the need for column chromatography, making it a safer and more efficient alternative.
Implementation Method 1
reacting 2' ,3'-O-isopropylidene cytidine sulfate with isobutyric anhydride in a solvent in the presence of a non-nucleophilic base to obtain a 5'-isobutyryl ester
Implementation Method 2
reacting the reaction product obtained from step-a with para-toluenesulphonic acid monohydrate to obtain a 5'-isobutyryl cytidine acid salt which is free from the amide impurity
Implementation Method 3
deprotection of the acetonide group was also observed and directly 5'-isobutyrylcytidine tosylate was obtained
Implementation Method 4
converting the 5'-isobutyryl cytidine acid salt to its free base and reacting the free base with hydroxylamine to obtain molnupiravir
Data Source
AI summary
A process for the preparation of Molnupiravir of formula (I), an antiviral drug under investigation for the treatment of Covid-19, is provided comprising reacting 2'-3'-isopropylidene cytidine with isobutyric anhydride in the presence of a base to obtain 5'-isobutyric ester having an amide impurity. Treating the reaction mixture with para-toluenesulphonic acid monohydrate results in acetonide deprotection giving pure isobutyric cytidine tosylate salt which is free from the amide impurity. Conversion of tosylate salt into free base and reacting with hydroxylamine gives Molnupiravir.