Rhodium-Catalyzed C–H Amination. An Enabling Method for Chemical Synthesis

Bois, J. Du

doi:10.1021/op200046v

Cited by 263 publications

(99 citation statements)

References 73 publications

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“…1a,2,4 Dirhodium complexes supported by strongly donating amidate ligands appear to be quickly oxidized under the reaction conditions, while electron-withdrawn carboxylate frameworks (e.g., α -amino acid derivatives, trifluoroacetate) are labile to ligand exchange. We have for some time sought non-rhodium metal complexes that promote competent N-atom transfer.…”

Section: Ruthenium Catalysts For Intramolecular Allylic C–h Insertionmentioning

confidence: 99%

Metal-Catalyzed Nitrogen-Atom Transfer Methods for the Oxidation of Aliphatic C–H Bonds

2012

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For more than a century, chemists have endeavored to discover and develop reaction processes that enable the selective oxidation of hydrocarbons. In the 1970s, Abramovitch and Yamada described the synthesis and electrophilic reactivity of sulfonyliminoiodinanes (RSO2N=IPh), demonstrating the utility of this new class of reagents to function as nitrene equivalents. Subsequent investigations by Breslow, Mansuy, and Müller would show such oxidants to be competent for alkene and saturated hydrocarbon functionalization when combined with transition metal salts or metal complexes, namely those of Mn, Fe, and Rh. Here, we trace our own studies to develop N-atom transfer technologies for C–H and π-bond oxidation. This Account discusses advances in both intra- and intermolecular amination processes mediated by dirhodium and diruthenium complexes, as well as the mechanistic foundations of catalyst reactivity and arrest. Explicit reference is given to questions that remain unanswered and to problem areas that are rich for discovery. A fundamental advance in amination technology has been the recognition that iminoiodinane oxidants can be generated in situ in the presence of a metal catalyst that elicits subsequent N-atom transfer. Under these conditions, both dirhodium and diruthenium lantern complexes function as competent catalysts for C–H bond oxidation with a range of nitrogen sources (e.g., carbamates, sulfamates, sulfamides, etc.), many of which will not form isolable iminoiodinane equivalents. Practical synthetic methods and applications thereof have evolved in parallel with inquiries into the operative reaction mechanism(s). For the intramolecular dirhodium-catalyzed process, the body of experimental and computational data is consistent with a concerted asynchronous C–H insertion pathway, analogous to the consensus mechanism for Rh-carbene transfer. Other studies reveal that the bridging tetracarboxylate ligand groups, which shroud the dirhodium core, are labile to exchange under standard reaction conditions. This information has led to the generation of chelating dicarboxylate dinuclear rhodium complexes, exemplified by Rh2(esp)2. The performance of this catalyst system is unmatched by other dirhodium complexes in both intra- and intermolecular C–H amination reactions. Tetra-bridged, mixed-valent diruthenium complexes function as effective promoters of sulfamate ester oxidative cyclization. These catalysts can be crafted with ligand sets other than carboxylates and are more resistant to oxidation than their dirhodium counterparts. A range of experimental and computational mechanistic data amassed with the tetra-2-oxypyridinate diruthenium chloride complex, [Ru2(hp)4Cl], has established the insertion event as a stepwise pathway involving a discrete radical intermediate. These data contrast dirhodium-catalyzed C–H amination and offer a cogent model for understanding the divergent chemoselectivity trends observed between the two catalyst types. This work constitutes an important step toward the ultimate goal of achiev...

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Section: Ruthenium Catalysts For Intramolecular Allylic C–h Insertionmentioning

confidence: 99%

Metal-Catalyzed Nitrogen-Atom Transfer Methods for the Oxidation of Aliphatic C–H Bonds

2012

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“…The use of Rh 2 (esp) 2 , a catalyst with enhanced stability, 35,36 in refluxing dichloroethane (DCE) permitted the desired aminations at concentrations as high as 0.5 M and catalyst loadings as low as 0.5 mol%; under these conditions, the desired cyclic sulfamate 8 was produced in moderate-to-good yields in less than 30 minutes. At lower catalyst loadings or concentrations above 0.2 M, small amounts of unidentified byproducts were observed, resulting in reduced yields of cyclic sulfamate 8 after purification.…”

Section: Resultsmentioning

confidence: 99%

An expedient synthesis of maraviroc (UK-427,857) via C–H functionalization

Bedell

Hone

Bois

et al. 2015

Tetrahedron Letters

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“…We then postulated that this intermediate could be accessed from 59 via rhodium-catalyzed benzylic and allylic C-H amination reactions, followed by an intramolecular nucleophilic attack of a nitrogen atom on a sulfamate group, based on Du Bois' protocol. 76,77) Since, to our knowledge, such an approach to heterocyclic compounds had not been reported previously, we became interested in probing the scope and limitation of this particular pyrrolidine synthesis. 78) We prepared a panel of various substitution patterns of cyclic sulfamates 61 from alcohols 60 by sulfamation, rhodium-catalyzed C-H amination, and butoxycarbonylation and explored the feasibility of their cyclizations.…”

Section: Total Synthesis Of Dysiherbainementioning

confidence: 99%

Total Synthesis of Biologically Active Natural Products Based on Highly Selective Synthetic Methodologies

Hatakeyama

2014

CHEMICAL & PHARMACEUTICAL BULLETIN

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Total syntheses of structurally and biologically intriguing natural products relying on new synthetic methodologies are described. This article features cinchona alkaloid-catalyzed asymmetric Morita-BaylisHillman reactions, heterocycle syntheses based on rhodium-catalyzed C-H amination and indium-catalyzed Conia-ene reactions, and their utilization for the syntheses of the phoslactomycin family of antibiotics, glutamate receptor agonists and antagonists, and alkaloids with characteristic highly substituted pyrrolidinone core structures.

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Rhodium-Catalyzed C–H Amination. An Enabling Method for Chemical Synthesis

Cited by 263 publications

References 73 publications

Metal-Catalyzed Nitrogen-Atom Transfer Methods for the Oxidation of Aliphatic C–H Bonds

Metal-Catalyzed Nitrogen-Atom Transfer Methods for the Oxidation of Aliphatic C–H Bonds

An expedient synthesis of maraviroc (UK-427,857) via C–H functionalization

Total Synthesis of Biologically Active Natural Products Based on Highly Selective Synthetic Methodologies

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