One-Pot Synthesis of 5-Alkylthio-1,2,4-Thiadiazoles and Ketene Dithioacetals
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Solution Overview
Problem
The synthesis of 5-alkylthio-1,2,4-thiadiazoles (ATTDs) and ketene dithioacetals (KDTAs) is limited by the scarcity of readily available reagents and methods, particularly for producing ATTDs without using 1,2,4-thiadiazole-5-thione intermediates and KDTAs lacking electron-withdrawing groups on the α-carbon.
Innovation Solution
A one-pot synthesis method is developed using amidines, carbon disulfide, and alkyl imidazole-1-carbodithioate molecules to form dithiocarbamate compounds, which are then converted into 5-alkylthio-1,2,4-thiadiazoles, and dimethyl methylphosphonate is reacted with disulfides and aldehydes to produce ketene dithioacetals, simplifying the process and improving yields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional methods are used to synthesize 5-alkylthio-1,2,4-thiadiazoles, then the synthesis can be performed with established reagents, but the process requires multiple steps including 1,2,4-thiadiazole-5-thione intermediates and uses scarce reagents
Solution Approach 1:
The patent combines multiple synthesis steps into a one-pot procedure where amidine, carbon disulfide, and alkyl halide react simultaneously to form 5-alkylthio-1,2,4-thiadiazoles. This eliminates the need for isolating 1,2,4-thiadiazole-5-thione intermediates and performs S-alkylation in the same reaction vessel, thereby simplifying the manufacturing process and reducing the number of operational steps.
Solution Approach 2:
The patent incorporates all necessary reagents (amidine, carbon disulfide, and alkyl halide) at the beginning of the reaction in a single vessel, allowing the complete synthesis sequence to proceed without intermediate isolation. This preliminary preparation of the reaction mixture eliminates subsequent purification and isolation steps that would otherwise be required.
2Adaptability or versatility
If conventional synthesis methods are used for ketene dithioacetals, then established reagents can be employed, but electron-withdrawing groups on the α-carbon are required and reagents are scarce
Solution Approach 1:
The patent changes the reaction parameters by using dimethyl methylphosphonate instead of traditional reagents that require electron-withdrawing groups. This parameter change in the starting material allows the synthesis of ketene dithioacetals without the need for electron-withdrawing substituents on the α-carbon, thereby expanding substrate scope and using more readily available reagents.
3Productivity
If traditional synthesis procedures are employed, then standard conditions can be used, but reaction time is extended and yields are reduced
Solution Approach 1:
The patent maintains continuous reaction conditions in a one-pot procedure where all transformations occur sequentially in the same vessel without interruption for isolation or purification. This continuous action allows the reaction to proceed efficiently to completion, achieving high yields within 24 hours by eliminating downtime associated with intermediate handling.
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 provides a mild, efficient, and competitive synthesis of ATTDs and KDTAs, achieving modest to good yields under mild conditions within 24 hours, addressing the limitations of existing methods by simplifying the reaction and reducing the need for scarce reagents.
Implementation Method 1
reacting the starting material with carbon disulfide or an alkyl imidazole-1-carbodithioate molecule to form a dithiocarbamate compound
Implementation Method 2
converting the dithiocarbamate compound to a compound of formula (I)
Implementation Method 3
dimethyl methylphosphonate is reacted with disulfides and aldehydes to produce ketene dithioacetals
Data Source
AI summary
The present application relates to compounds of formulae (I)-(VII) as defined herein, compositions containing these compounds, methods of their use, and methods of making. The compounds have nematacide activity.