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 η²-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 η²-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 η²-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 η²-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 η²-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 η²-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 η²-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 η²-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