Aminothiol Ester Synthesis via Salt Intermediates
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Solution Overview
Problem
Existing methods for preparing aminothiol ester compounds face challenges due to the uncertainty in supply and toxicity of reagents like 3-chloro-3-methylbut-1-yne and carbon oxysulfide, as well as difficulties in scaling up purification processes, which affect yield and product stability.
Innovation Solution
A method involving a series of reactions without the use of toxic reagents, including the steps of reacting a compound with an inorganic or organic acid, a base, CO2, an alkyl chloroformate, and an SMe− anion precursor, where intermediate products are not isolated or purified, to produce aminothiol ester compounds and their salts, using reagents that are less likely to sublime during the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first step uses commercial 3-chloro-3-methylbut-1-yne, then the reaction can proceed, but the supply is uncertain and purity is variable affecting yield
Solution Approach 1:
The patent prepares 3-chloro-3-methylbut-1-yne in advance through a two-step synthesis from commercially available 2-methylbut-3-yn-2-ol and HCl, then converts it to the amine salt form for storage. This preliminary preparation ensures both supply reliability and consistent purity for subsequent reactions, eliminating dependence on uncertain commercial sources.
2Manufacturing precision
If purification steps are implemented for the first step product, then purity improves, but the steps are difficult to transpose to large scale
Solution Approach 1:
The patent changes the physical state and chemical form of the intermediate product by converting it into a stable amine salt (e.g., hydrochloride salt). This parameter change allows the product to be stored and handled in a purified form without requiring complex purification steps at each stage, making the process easily scalable.
3Reliability
If carbon oxysulfide (COS) is used in the second step, then the reaction proceeds, but it is toxic and supply is uncertain
Solution Approach 1:
The patent extracts and eliminates the toxic carbon oxysulfide reagent from the synthesis pathway. Instead, it uses a multi-step alternative approach involving amine salt formation, deprotonation with base, CO2 addition, and thiol esterification, thereby removing the harmful substance while maintaining synthetic capability.
4Productivity
If products and reagents are used that may sublime during purification, then the reaction proceeds, but purification becomes difficult
Solution Approach 1:
The patent changes the physical properties of intermediates by converting them into stable salt forms (e.g., amine hydrochlorides) that have higher melting points and do not sublime during purification. This parameter change enables straightforward purification techniques while maintaining reaction efficiency.
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 approach allows for the efficient preparation of aminothiol ester compounds and their salts with improved yield and stability, avoiding the use of toxic substances and simplifying the purification process, thus overcoming the limitations of prior methods.
Implementation Method 1
reaction of a compound of formula (II) with an inorganic acid or an organic acid
Implementation Method 2
reaction of the compound obtained in step a) with a base
Implementation Method 3
reaction of the compound obtained in step b) with CO2
Implementation Method 4
reaction of the compound obtained in step c) with an alkyl chloroformate, i.e. a reagent that is likely to form, with the compound obtained in stage c), an acid halide or a reagent likely to form, with the compound obtained in step c), a mixed anhydride
Implementation Method 5
reaction of the compound obtained in step d) with an SMe− anion precursor compound
Data Source
AI summary
A process for preparing aminothiol ester compounds and salts thereof. The present invention relates to a process for preparing compounds of formula (I), (I) comprising the following steps: a) reacting a compound of formula (II) with an inorganic acid or an organic acid, (II) b) reacting the compound obtained in step a) with a base; c) reacting the compound obtained in step b) with CO2; d) reacting the compound obtained in step c) with an alkyl chloroformate, a reagent capable of forming, with the compound obtained in step c), an acid halide, or a reagent capable of forming, with the compound obtained in step c), a mixed anhydride; e) reacting the compound obtained in step d) with an SMe anion precursor compound.