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1,4-pentadienyl-3-sulfonamides: frameworks for "disfavored" radical cascade cyclizations
S Bommezijn1, C G Martin, A R Kennedy
1Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow G1 1XL, UK.
Organic Letters
|October 12, 2001
Summary
Radical cyclization of 1,4-pentadienyl-3-sulfonamides yields unexpected products. Even strained ring systems form via 4-exo-trig pathways, alongside disfavored 5-endo-trig reactions.
Area of Science:
- Organic Chemistry
- Reaction Mechanisms
Background:
- Radical cyclization reactions are fundamental in organic synthesis.
- Understanding regioselectivity in radical cyclizations is crucial for predicting reaction outcomes.
Purpose of the Study:
- To investigate the radical cyclization of 1,4-pentadienyl-3-sulfonamides.
- To determine the factors influencing the regioselectivity of these reactions.
Main Methods:
- Subjecting 1,4-pentadienyl-3-sulfonamides to radical cyclization conditions.
- Analyzing the resulting products to identify reaction pathways.
Main Results:
- Products from both 5-endo-trig and 4-exo-trig cyclizations were observed.
- The 4-exo-trig pathway was favored even when it resulted in strained bicyclo[3.2.0] ring systems.
Conclusions:
- The radical cyclization of 1,4-pentadienyl-3-sulfonamides is not regioselective.
- Strained ring systems can be accessed through 4-exo-trig radical cyclizations.