Ring-Opening Carbonyl-Olefin Metathesis of Norbornenes
2019
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.
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
0
References
1
Citations
NaN
KQI