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Ring-Opening Carbonyl-Olefin Metathesis of Norbornenes

preprint
submitted on 17.12.2019 and posted on 20.12.2019 by Janis Jermaks, Phong K. Quach, Zara M. Seibel, Julien Pomarole, Tristan Lambert

A computational and experimental study of the hydrazine-catalyzed ring-opening carbonyl-olefin metathesis of norbornenes is described. Detailed theoretical investigation of the energetic landscape for the full reaction pathway with six different hydrazines revealed several crucial aspects for the design of next-generation hydrazine catalysts. This study indicated that a [2.2.2]-bicyclic hydrazine should offer substantially increased reactivity versus the previously reported [2.2.1]-hydrazine due to a lowered activation barrier for the rate-determining cycloreversion step, a prediction which was verified experimentally. Optimized conditions for both cycloaddition and cycloreversion steps were identified, and a brief substrate scope study for each was conducted. A complication for catalysis was found to be the slow hydrolysis of the ring-opened hydrazonium intermediates, which were shown to suffer from a competitive and irreversible cycloaddition with a second equivalent of norbornene. This problem was overcome by the strategic incorporation of a bridgehead methyl group on the norbornene ring, leading to the first demonstrated catalytic carbonyl-olefin metathesis of norbornene rings.

Funding

Enantioselective Bronsted Acid Catalysis with Chiral Cyclopentadienes

National Institute of General Medical Sciences

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New Platforms for Catalysis

Directorate for Mathematical & Physical Sciences

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Catalytic Platforms Using Aromatic Ions and Other Charged Species

National Institute of General Medical Sciences

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American Chemical Society Petroleum Research Fund 53705-ND1

History

Email Address of Submitting Author

thl36@cornell.edu

Institution

Cornell University

Country

USA

ORCID For Submitting Author

0000-0002-7720-3290

Declaration of Conflict of Interest

none

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