15 research outputs found
Investigations into Ruthenium Metathesis Catalysts with Six-Membered Chelating NHC Ligands: Relationship between Catalyst Structure and Stereoselectivity
A series
of ruthenium catalysts bearing five-membered chelating
NHC architectures that exhibit very high <i>Z</i>-selectivity
in a variety of metathesis reactions have recently been reported.
It was envisioned that catalysts possessing six-membered chelates
could similarly exhibit high <i>Z</i>-selectivity and address
limitations of this methodology. We thus prepared a number of new
catalysts and systematically investigated the impact of the NHC and
anionic ligand on their stereoselectivity. In standard metathesis
assays, only catalysts containing six-membered chelated NHC structures
and η<sup>2</sup>-bound anionic ligands favored the <i>Z</i>-olefin products. In addition, substitution with bulkier <i>N</i>-aryl groups led to improved <i>Z</i>-selectivity.
The effect of ligand structure on stereoselectivity discovered in
this study will be useful in the future design of highly active and <i>Z</i>-selective ruthenium catalysts
Investigations into Ruthenium Metathesis Catalysts with Six-Membered Chelating NHC Ligands: Relationship between Catalyst Structure and Stereoselectivity
A series
of ruthenium catalysts bearing five-membered chelating
NHC architectures that exhibit very high <i>Z</i>-selectivity
in a variety of metathesis reactions have recently been reported.
It was envisioned that catalysts possessing six-membered chelates
could similarly exhibit high <i>Z</i>-selectivity and address
limitations of this methodology. We thus prepared a number of new
catalysts and systematically investigated the impact of the NHC and
anionic ligand on their stereoselectivity. In standard metathesis
assays, only catalysts containing six-membered chelated NHC structures
and η<sup>2</sup>-bound anionic ligands favored the <i>Z</i>-olefin products. In addition, substitution with bulkier <i>N</i>-aryl groups led to improved <i>Z</i>-selectivity.
The effect of ligand structure on stereoselectivity discovered in
this study will be useful in the future design of highly active and <i>Z</i>-selective ruthenium catalysts
Investigations into Ruthenium Metathesis Catalysts with Six-Membered Chelating NHC Ligands: Relationship between Catalyst Structure and Stereoselectivity
A series
of ruthenium catalysts bearing five-membered chelating
NHC architectures that exhibit very high <i>Z</i>-selectivity
in a variety of metathesis reactions have recently been reported.
It was envisioned that catalysts possessing six-membered chelates
could similarly exhibit high <i>Z</i>-selectivity and address
limitations of this methodology. We thus prepared a number of new
catalysts and systematically investigated the impact of the NHC and
anionic ligand on their stereoselectivity. In standard metathesis
assays, only catalysts containing six-membered chelated NHC structures
and η<sup>2</sup>-bound anionic ligands favored the <i>Z</i>-olefin products. In addition, substitution with bulkier <i>N</i>-aryl groups led to improved <i>Z</i>-selectivity.
The effect of ligand structure on stereoselectivity discovered in
this study will be useful in the future design of highly active and <i>Z</i>-selective ruthenium catalysts
Investigations into Ruthenium Metathesis Catalysts with Six-Membered Chelating NHC Ligands: Relationship between Catalyst Structure and Stereoselectivity
A series
of ruthenium catalysts bearing five-membered chelating
NHC architectures that exhibit very high <i>Z</i>-selectivity
in a variety of metathesis reactions have recently been reported.
It was envisioned that catalysts possessing six-membered chelates
could similarly exhibit high <i>Z</i>-selectivity and address
limitations of this methodology. We thus prepared a number of new
catalysts and systematically investigated the impact of the NHC and
anionic ligand on their stereoselectivity. In standard metathesis
assays, only catalysts containing six-membered chelated NHC structures
and η<sup>2</sup>-bound anionic ligands favored the <i>Z</i>-olefin products. In addition, substitution with bulkier <i>N</i>-aryl groups led to improved <i>Z</i>-selectivity.
The effect of ligand structure on stereoselectivity discovered in
this study will be useful in the future design of highly active and <i>Z</i>-selective ruthenium catalysts
Investigations into Ruthenium Metathesis Catalysts with Six-Membered Chelating NHC Ligands: Relationship between Catalyst Structure and Stereoselectivity
A series
of ruthenium catalysts bearing five-membered chelating
NHC architectures that exhibit very high <i>Z</i>-selectivity
in a variety of metathesis reactions have recently been reported.
It was envisioned that catalysts possessing six-membered chelates
could similarly exhibit high <i>Z</i>-selectivity and address
limitations of this methodology. We thus prepared a number of new
catalysts and systematically investigated the impact of the NHC and
anionic ligand on their stereoselectivity. In standard metathesis
assays, only catalysts containing six-membered chelated NHC structures
and η<sup>2</sup>-bound anionic ligands favored the <i>Z</i>-olefin products. In addition, substitution with bulkier <i>N</i>-aryl groups led to improved <i>Z</i>-selectivity.
The effect of ligand structure on stereoselectivity discovered in
this study will be useful in the future design of highly active and <i>Z</i>-selective ruthenium catalysts
Investigations into Ruthenium Metathesis Catalysts with Six-Membered Chelating NHC Ligands: Relationship between Catalyst Structure and Stereoselectivity
A series
of ruthenium catalysts bearing five-membered chelating
NHC architectures that exhibit very high <i>Z</i>-selectivity
in a variety of metathesis reactions have recently been reported.
It was envisioned that catalysts possessing six-membered chelates
could similarly exhibit high <i>Z</i>-selectivity and address
limitations of this methodology. We thus prepared a number of new
catalysts and systematically investigated the impact of the NHC and
anionic ligand on their stereoselectivity. In standard metathesis
assays, only catalysts containing six-membered chelated NHC structures
and η<sup>2</sup>-bound anionic ligands favored the <i>Z</i>-olefin products. In addition, substitution with bulkier <i>N</i>-aryl groups led to improved <i>Z</i>-selectivity.
The effect of ligand structure on stereoselectivity discovered in
this study will be useful in the future design of highly active and <i>Z</i>-selective ruthenium catalysts
Investigations into Ruthenium Metathesis Catalysts with Six-Membered Chelating NHC Ligands: Relationship between Catalyst Structure and Stereoselectivity
A series
of ruthenium catalysts bearing five-membered chelating
NHC architectures that exhibit very high <i>Z</i>-selectivity
in a variety of metathesis reactions have recently been reported.
It was envisioned that catalysts possessing six-membered chelates
could similarly exhibit high <i>Z</i>-selectivity and address
limitations of this methodology. We thus prepared a number of new
catalysts and systematically investigated the impact of the NHC and
anionic ligand on their stereoselectivity. In standard metathesis
assays, only catalysts containing six-membered chelated NHC structures
and η<sup>2</sup>-bound anionic ligands favored the <i>Z</i>-olefin products. In addition, substitution with bulkier <i>N</i>-aryl groups led to improved <i>Z</i>-selectivity.
The effect of ligand structure on stereoselectivity discovered in
this study will be useful in the future design of highly active and <i>Z</i>-selective ruthenium catalysts
Investigations into Ruthenium Metathesis Catalysts with Six-Membered Chelating NHC Ligands: Relationship between Catalyst Structure and Stereoselectivity
A series
of ruthenium catalysts bearing five-membered chelating
NHC architectures that exhibit very high <i>Z</i>-selectivity
in a variety of metathesis reactions have recently been reported.
It was envisioned that catalysts possessing six-membered chelates
could similarly exhibit high <i>Z</i>-selectivity and address
limitations of this methodology. We thus prepared a number of new
catalysts and systematically investigated the impact of the NHC and
anionic ligand on their stereoselectivity. In standard metathesis
assays, only catalysts containing six-membered chelated NHC structures
and η<sup>2</sup>-bound anionic ligands favored the <i>Z</i>-olefin products. In addition, substitution with bulkier <i>N</i>-aryl groups led to improved <i>Z</i>-selectivity.
The effect of ligand structure on stereoselectivity discovered in
this study will be useful in the future design of highly active and <i>Z</i>-selective ruthenium catalysts
Stereoselective Access to <i>Z</i> and <i>E</i> Macrocycles by Ruthenium-Catalyzed <i>Z</i>‑Selective Ring-Closing Metathesis and Ethenolysis
The first report of <i>Z</i>-selective macrocyclizations
using a ruthenium-based metathesis catalyst is described. The selectivity
for <i>Z</i> macrocycles is consistently high for a diverse
set of substrates with a variety of functional groups and ring sizes.
The same catalyst was also employed for the <i>Z</i>-selective
ethenolysis of a mixture of <i>E</i> and <i>Z</i> macrocycles, providing the pure <i>E</i> isomer. Notably,
an ethylene pressure of only 1 atm was required. These methodologies
were successfully applied to the construction of several olfactory
macrocycles as well as the formal total synthesis of the cytotoxic
alkaloid motuporamine C
Highly Active Ruthenium Metathesis Catalysts Exhibiting Unprecedented Activity and <i>Z</i>‑Selectivity
A novel chelated ruthenium-based metathesis catalyst
bearing an <i>N</i>-2,6-diisopropylphenyl group is reported
and displays near-perfect
selectivity for the <i>Z</i>-olefin (>95%), as well as
unparalleled
TONs of up to 7400, in a variety of homodimerization and industrially
relevant metathesis reactions. This derivative and other new catalytically
active species were synthesized using an improved method employing
sodium carboxylates to induce the salt metathesis and C–H activation
of these chelated complexes. All of these new ruthenium-based catalysts
are highly <i>Z</i>-selective in the homodimerization of
terminal olefins