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An S(N)2-like transition state for alkene episulfidation by dinitrogen sulfide
1Department of Chemistry, The Hong Kong University of Science & Technology, Clearwater Bay, Kowloon, Hong Kong, China. zhixiang@chem.ucla.edu
The Journal of Organic Chemistry
|July 19, 2003
Summary
Dinitrogen sulfide performs alkene episulfidation via an S(N)2-like pathway. This one-step mechanism is favored over a two-step cycloaddition due to lower geometric strain in its transition state.
Area of Science:
- Organic Chemistry
- Reaction Mechanisms
- Sulfur Chemistry
Background:
- Episulfidation of alkenes is a key transformation in organic synthesis.
- Dinitrogen sulfide (N2S) is a reactive species that can be generated in situ.
- Understanding the mechanism of N2S reactions is crucial for synthetic applications.
Purpose of the Study:
- To elucidate the reaction mechanism of alkene episulfidation mediated by dinitrogen sulfide.
- To investigate the factors governing the preference between different mechanistic pathways.
Main Methods:
- Generation of dinitrogen sulfide via thermolysis of 5-aryloxy-1,2,3,4-thiatriazoles.
- Reaction of dinitrogen sulfide with various alkenes.
- Computational studies to analyze transition states and reaction energetics.
Main Results:
- Episulfidation of alkenes proceeds via a concerted S(N)2-like mechanism.
- The reaction involves simultaneous sulfur atom transfer and dinitrogen extrusion.
- A two-step (2+3) dipolar cycloaddition pathway was found to be less favorable.
Conclusions:
- The S(N)2-like pathway is kinetically preferred over the (2+3) cycloaddition pathway.
- Higher geometric distortion penalty in the (2+3) transition state favors the concerted mechanism.
- This study provides insights into the reactivity of dinitrogen sulfide in organic synthesis.