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Asymmetric Ni(II)/Cr(II)-mediated coupling reaction: stoichiometric process
Zhao-Kui Wan1, Hyeong-Wook Choi, Fu-An Kang
1Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, Massachusetts 02138, USA.
Organic Letters
|December 6, 2002
Summary
Sulfonamide ligands coordinate to chromium(III) salts. These ligands facilitate asymmetric nickel/chromium-catalyzed coupling reactions, demonstrating significant synthetic utility with complex molecules like halichondrins.
Area of Science:
- Organometallic Chemistry
- Asymmetric Catalysis
- Synthetic Organic Chemistry
Background:
- Sulfonamide derivatives serve as versatile ligands in coordination chemistry.
- Chromium and nickel catalysis are crucial for forming carbon-carbon bonds.
- Asymmetric synthesis is vital for producing enantiomerically pure compounds.
Purpose of the Study:
- To characterize a specific sulfonamide as a tridentate ligand for chromium(III).
- To evaluate the efficacy of a class of sulfonamide ligands in asymmetric Ni/Cr-mediated coupling reactions.
- To demonstrate the synthetic potential of these ligands in complex molecule synthesis.
Main Methods:
- X-ray crystallography was employed to determine the coordination mode of the sulfonamide ligand.
- Nickel and chromium catalysts were utilized in a mediated coupling reaction.
- The synthetic application was tested using the C14-C38 segment of halichondrins.
Main Results:
- A sulfonamide ligand with R(1)=i-Pr, R(2)=Me, R(3)=Me was confirmed as a tridentate ligand to a Cr(III) salt.
- Ligands of the type R(1)=t-Bu, R(2)=2-naphthyl, R(3)=Me proved effective in asymmetric Ni/Cr-mediated coupling.
- The synthetic potential was successfully demonstrated in the context of halichondrin synthesis.
Conclusions:
- The studied sulfonamides are effective tridentate ligands for Cr(III).
- These ligands enable efficient asymmetric Ni/Cr-catalyzed coupling reactions.
- The methodology shows promise for the synthesis of complex natural products.
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