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Published on: April 19, 2019
Carbodicarbene-Stibenium Ion-Mediated Functionalization of C(sp3)-H and C(sp)-H Bonds
Levi Warring1, Karl S Westendorff1,2, Marc T Bennett3
1Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA-02139, USA.
This study demonstrates main-group element-mediated C-H activation using a stibenium ion. The research details the successful activation of both sp3 and sp C-H bonds in acetonitrile and alkynes, respectively.
Area of Science:
- Organometallic Chemistry
- Main-Group Chemistry
- Catalysis
Background:
- C-H activation by main-group elements is challenging due to high reactivity.
- Developing design principles for heavier elements is limited.
- Stibenium ions offer a potential platform for controlled reactivity.
Purpose of the Study:
- To investigate C-H bond activation mediated by a stibenium ion.
- To explore the reactivity of [(pyCDC)Sb]3+ with acetonitrile and terminal alkynes.
- To elucidate the mechanism of C-H activation and product formation.
Main Methods:
- Synthesis of the stibenium ion [(pyCDC)Sb][NTf2]3.
- Reaction of the stibenium ion with acetonitrile and terminal alkynes in the presence of a base.
- Kinetic analyses to determine reaction rates.
- Computational studies to understand the reaction mechanism.
- Characterization of the resulting stiba-methylene nitrile and stiba-alkynyl adducts.
Main Results:
- Successful C(sp3)-H bond activation of acetonitrile to form a stiba-methylene nitrile complex.
- Successful C(sp)-H bond activation of terminal alkynes to form stiba-alkynyl adducts with high specificity.
- Elucidation of a mechanism involving acetonitrile coordination and subsequent deprotonation.
- Demonstration of the reactivity of the adducts with iodine to form iodoalkanes and regenerate the Sb trication.
Conclusions:
- The stibenium ion [(pyCDC)Sb][NTf2]3 is an effective reagent for main-group element-mediated C-H activation.
- The study provides insights into the mechanism of C-H activation by heavy main-group elements.
- This work expands the scope of C-H activation chemistry and offers new synthetic pathways.
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