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Fully Substituted Thiophene Synthesis via (3 + 2) with Thiadiazoles
Ethan A Wappes1, Kyle S McClymont2, Xiaoying Zheng1
1Department of Discovery Process Chemistry, Merck & Co., Inc., South San Francisco, California 94080, United States.
A novel Rh-catalyzed cycloaddition method provides access to highly substituted dihydrothiophenes and thiophenes. This modular strategy efficiently couples bicyclic 1,2,3 thiadiazoles with alkenes, complementing traditional synthesis approaches.
Area of Science:
- Organic Chemistry
- Synthetic Chemistry
Background:
- Traditional stepwise synthesis can be lengthy for complex molecules.
- Accessing highly substituted dihydrothiophenes and thiophenes remains a synthetic challenge.
Purpose of the Study:
- To report a new method for synthesizing highly substituted dihydrothiophenes and thiophenes.
- To develop a modular and efficient synthetic strategy.
Main Methods:
- Employing a Rh-catalyzed formal (3 + 2) cycloaddition reaction.
- Coupling bicyclic 1,2,3 thiadiazoles with various alkenes.
- Oxidizing the resulting dihydrothiophenes to thiophenes.
Main Results:
- Successfully generated densely functionalized dihydrothiophenes.
- Demonstrated the modularity of the reaction with diverse thiadiazoles and alkenes.
- Obtained corresponding thiophene products via oxidation.
Conclusions:
- The reported method offers a complementary and efficient route to substituted dihydrothiophenes and thiophenes.
- This Rh-catalyzed cycloaddition provides a powerful tool for synthetic chemists.
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