Journal ArticleDOI
Amination of benzylic C-H bonds by arylazides catalyzed by CoII-porphyrin complexes: a synthetic and mechanistic study.
Fabio Ragaini,Andrea Penoni,Emma Gallo,Stefano Tollari,Claudia Li Gotti,Marta Lapadula,Enrica Mangioni,Sergio Cenini +7 more
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TLDR
An excellent correlation between the logarithm of the rate for substituted toluenes relative to that of toluene and a radical parameter (sigma*JJ) alone was found, with no significant contribution by polar parameters.Abstract:
Co I I -porphyrin complexes catalyze the reaction of aromatic azides (ArN 3 ) with hydrocarbons that contain a benzylic group (ArR 1 R 2 CH) to give the corresponding amines (ArR 1 R 2 C-N-HAr). When at least one of the R substituents is hydrogen, the catalytic reaction proceeds further to give the imine ArRC=NAr in good yields. The reaction mechanism has been investigated. The reaction proceeds through a reversible coordination of the arylazide to the Co I I - porphyrin complex. This unstable adduct can either react with the hydrocarbon in the rate-determining step or decompose by a unimolecular mechanism to afford a putative "nitrene" complex, which reacts with more azide, but not with the hydrocarbon, to afford the byproduct diaryldiazene. The kinetics of the catalytic reaction have been investigated for a range of azides and substituted toluenes. Arylazides with electron-withdrawing substituents react at a faster rate and a good correlation is found between the log(k) and the Taft parameters. On the other hand, an excellent correlation between the logarithm of the rate for substituted toluenes relative to that of toluene and a radical parameter (σ . J J ) alone was found, with no significant contribution by polar parameters. An explanation has been proposed for this anomalous effect and for the very high isotopic effect (k H /k D = 14) found.read more
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Journal ArticleDOI
Organic Azides: An Exploding Diversity of a Unique Class of Compounds
TL;DR: In this Review, the fundamental characteristics of azide chemistry and current developments are presented and the focus will be placed on cycloadditions (Huisgen reaction), aza ylide chemistry, and the synthesis of heterocycles.
Journal ArticleDOI
Transition Metal-Catalyzed C–H Amination: Scope, Mechanism, and Applications
TL;DR: This Review comprehensively highlights recent advances in intra- and intermolecular C-H amination reactions utilizing late transition metal-based catalysts using mechanistic scaffolds and types of reactions.
Journal ArticleDOI
Catalytic C-H amination: recent progress and future directions.
TL;DR: The careful design of reagents and catalysts now provides efficient conditions for exquisitely selective intramolecular as well as intermolecular nitrene C-H insertion and opens new opportunities complementary to those offered by nitrenes.
Journal ArticleDOI
Intermolecular Amidation of Unactivated sp2 and sp3 C−H Bonds via Palladium-Catalyzed Cascade C−H Activation/Nitrene Insertion
TL;DR: This communication describes the Pd(OAc)2-catalyzed intermolecular amidation reactions of unactivated sp2 and sp3 C-H bonds using primary amides and potassium persulfate, which generated reactive nitrene species which then reacted with the cyclopalladated complex.
Journal ArticleDOI
Catalytic C–H functionalization by metalloporphyrins: recent developments and future directions
Hongjian Lu,X. Peter Zhang +1 more
TL;DR: This tutorial review describes metalloporphyrin-based catalytic systems for the functionalization of different types of sp(3) C-H bonds, both inter- and intramolecularly, including challenging primary C- H bonds.
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