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While remarkable progress has been made over the past decade, new design strategies for chiral catalysts in enantioselective C(sp3)-H functionalization reactions are still highly desirable. In particular, the ability to use attractive non-covalent interactions for rate acceleration and enantiocontrol would significantly expand the current arsenal for asymmetric metal catalysis. Herein, we report the development of a highly enantioselective Ir(III)-catalyzed intramolecular C(sp3)-H amidation reaction of dioxazolone substrates for synthesis of optically enriched γ-lactams using a newly designed γ-amino acid-based chiral ligand. This Ir-catalyzed reaction proceeds with excellent efficiency and with outstanding enantioselectivity for both activated and unactivated alkyl C(sp3)-H bonds under very mild conditions. It offers the first general route for asymmetric synthesis of γ-alkyl γ-lactams. Water was found to be a unique co-solvent to achieve excellent enantioselectivity for γ-aryl lactam production. Mechanistic studies revealed that the ligands form a well-defined groove-type chiral pocket around the Ir center. The hydrophobic effect of this pocket allows facile stereo-controlled binding of substrates in polar or aqueous media. In-stead of capitalizing on steric repulsions as in the conventional approaches, this new Ir catalyst operates through an unprecedented enantiocontrol mechanism for intramolecular nitrenoid C-H insertion featuring multiple attractive non-covalent interactions.
This article was published in the following journal.
Name: Journal of the American Chemical Society
Cp*Cobalt(III)-catalyzed enantioselective C-H amidation of ferrocenes using monoprotected amino acids (MPAAs) as chiral ligands was developed. The reaction was performed under mild conditions in high ...
We report the Ru-catalyzed enantioselective annulation of 1,4,2-dioxazol-5-ones to furnish γ-lactams in up to 97% yield and 98% ee via intramolecular carbonylnitrene C-H insertion. By employing chira...
The enantioselective Pd(II)-catalyzed γ-C-H arylation of picolinamides with a chiral BINOL phosphate ligand was explored using density functional theory (DFT). Enantioselectivity arises from attracti...
An iridium-catalyzed asymmetric allylation of dioxindoles, 3-hydroxyoxindoles, regulated by prosthetic groups has been accomplished under mild conditions. The methodology is applicable to a diverse ar...
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The purpose of this study is to demonstrate the advantage of using a gold alloy tip electrode over a platinum/iridium alloy tip electrode in ablation of the cavotricuspid isthmus in patien...
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Unstable isotopes of iridium that decay or disintegrate emitting radiation. Ir atoms with atomic weights 182-190, 192, and 194-198 are radioactive iridium isotopes.
Screening techniques first developed in yeast to identify genes encoding interacting proteins. Variations are used to evaluate interplay between proteins and other molecules. Two-hybrid techniques refer to analysis for protein-protein interactions, one-hybrid for DNA-protein interactions, three-hybrid interactions for RNA-protein interactions or ligand-based interactions. Reverse n-hybrid techniques refer to analysis for mutations or other small molecules that dissociate known interactions.
Implanted fluid propulsion systems with self-contained power source for providing long-term controlled-rate delivery of drugs such as chemotherapeutic agents or analgesics. Delivery rate may be externally controlled or osmotically or peristatically controlled with the aid of transcutaneous monitoring.
The interactions of particles responsible for their scattering and transformations (decays and reactions). Because of interactions, an isolated particle may decay into other particles. Two particles passing near each other may transform, perhaps into the same particles but with changed momenta (elastic scattering) or into other particles (inelastic scattering). Interactions fall into three groups: strong, electromagnetic, and weak. (From McGraw-Hill Encyclopedia of Science & Technology, 7th ed)
Areas of attractive or repulsive force surrounding MAGNETS.