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Mild Isomerization of Conjugated Dienes Using Co-Mediated Hydrogen Atom Transfer
Kyle R Delgado1, Dustin D Youmans1, Steven T Diver1
1Department of Chemistry , University at Buffalo, The State University of New York , Amherst , New York 14260 , United States.
Organic Letters
|January 9, 2020
Summary
This study details a mild catalytic rearrangement of dienes into valuable trisubstituted dienes. The reaction proceeds with high yield and preserves stereochemistry, indicating a novel synthetic pathway.
Area of Science:
- Organic Chemistry
- Catalysis
- Synthetic Methodology
Background:
- Conjugated dienes are versatile building blocks in organic synthesis.
- Efficient methods for the synthesis of highly substituted dienes are crucial for accessing complex molecules.
- Existing rearrangement methods may lack generality or require harsh conditions.
Purpose of the Study:
- To develop a mild and high-yielding rearrangement of 1,3-disubstituted-1,3-dienes.
- To investigate the mechanism of this novel diene rearrangement.
- To explore the stereochemical outcome of the reaction.
Main Methods:
- Utilized a cobaloxime catalyst in conjunction with a silane cocatalyst.
- Performed deuterium labeling studies to elucidate the reaction mechanism.
- Analyzed the stereochemical integrity of chiral centers near the diene.
Main Results:
- Achieved a mild and high-yielding rearrangement of 1,3-disubstituted-1,3-dienes to 1,1,4-trisubstituted-1,3-dienes.
- Demonstrated that chiral centers adjacent to the conjugated diene were not racemized.
- Deuterium labeling studies supported a hydrogen atom transfer mechanism.
- Observed ring opening of a cyclopropane ring, indicating accessible radical intermediates.
Conclusions:
- The reported cobaloxime-catalyzed reaction provides an efficient route to valuable 1,1,4-trisubstituted dienes.
- The reaction mechanism involves hydrogen atom transfer and radical intermediates, with retention of stereochemistry.
- This methodology offers a mild and effective approach for diene synthesis and functionalization.
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