- Catalytic C(sp2)?H amination reactions using dinickel imides
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C?H amination reactions are valuable transformations for the construction of C?N bonds. Due to their relatively high bond dissociation energies, C(sp2)?H bonds are generally not susceptible toward direct nitrene insertion, necessitating alternative mechanisms for C?H activation. Here, we report that cationic dinuclear (NDI)Ni2 (NDI = naphthyridine?diimine) complexes catalyze intramolecular nitrene insertions into aryl and vinyl C(sp2)? H bonds. Mechanistic studies suggest that a bridging imido ligand supported at a Ni2 site induces C?H activation by a 1,2-addition pathway to generate an azametallacyclic intermediate. This organometallic mechanism contrasts with the electrocyclization/1,2-shift mechanism proposed for analogous transformations using Rh2 catalysts. The implications of these mechanistic differences for the stereoselectivity and chemoselectivity of C?H amination are described.
- Andjaba, John M.,Powers, Ian G.,Uyeda, Christopher,Zeller, Matthias
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p. 3794 - 3801
(2020/11/23)
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- Heterogeneous photocatalysis of azides: Extending nitrene photochemistry to longer wavelengths
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The photodecomposition of azides to generate nitrenes usually requires wavelengths in the 300 nm region. In this study, we show that this reaction can be readily performed in the UVA region (368 nm) when catalyzed by Pd-decorated TiO2. In aqueous medium the reaction leads to amines, with water acting as the H source; however, in non-protic and non-nucleophilic media, such as acetonitrile, nitrenes recombine to yield azo compounds, while azirine-mediated trapping occurs in the presence of nucleophiles. The heterogeneous process facilitates catalyst separation while showing great chemoselectivity and high yields.
- Argüello, Juan E.,Lanterna, Anabel E.,Lemir, Ignacio D.,Scaiano, Juan C.
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supporting information
p. 10239 - 10242
(2020/10/02)
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- Synthesis of indolines, indoles, and benzopyrrolizidinones from simple aryl azides
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A simple approach to prepare indolines and benzopyrrolizidinones from ortho-azidoallylbenzenes via a tandem radical addition/cyclization is described. The use of triethylborane to initiate and sustain the process provides the best results. Indolines are easily converted into the corresponding indoles by oxidation with manganese dioxide.
- Brucelle, Fran?ois,Renaud, Philippe
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p. 3048 - 3051
(2012/08/14)
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- Unexpected conversion of alkyl azides to alkyl iodides and of aryl azides to N-tert-butyl anilines
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In the presence of tert-butyl iodide, alkyl azides are converted into the corresponding iodides at room temperature, whereas, N-t-Bu anilines are obtained from aryl azides under the same experimental conditions. A mechanism is proposed to explain this unusual reactivity.
- Maury, Julien,Feray, Laurence,Bertrand, Michele P.,Kapat, Ajoy,Renaud, Philippe
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p. 9606 - 9611,6
(2020/08/20)
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- Synthetic studies on virantmycin. 1. Total synthesis of (±)-virantmycin and determination of its relative stereochemistry
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The efficient and stereospecific route to the tetrahydroquinoline ring models 3 and 4 of virantmycin has been developed by means of an intramolecular nitrene addition reaction as a key step. In the NOE experiments of 4 and 3 we revealed that a ring invers
- Morimoto, Yoshiki,Matsuda, Fuyuhiko,Shirahama, Haruhisa
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p. 10609 - 10630
(2007/10/03)
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- An efficient approach toward virantmycin: Stereospecific construction of tetrahydroquinoline ring system employing intramolecular nitrene-addition reaction
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An efficient and stereospecific synthesis of the tetrahydroquinoline ring system of the structurally unique alkaloid, virantmycin (1), has been achieved using intramolecular addition reaction of nitrene to olefin as a key step.
- Morimoto, Yoshiki,Matsuda, Fuyuhiko,Shirahama, Haruhisa
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p. 6031 - 6034
(2007/10/02)
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- Cyclization of Phenyl Azides with Homoallylic or Allylic Ortho Substituents and the Consequences of Triazoline Fragmentation
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o-(Allyloxy)phenyl azide (1) and 14 derivatives substituted on the allyl group were thermolyzed at 110-120 deg C to form benzoxazines (16), dihydroazirinobenzoxazines (17), or 3-alkenylbenzomorpholines (18, 19) through fragmentation of intermediate triazolines.With substituted allyl groups, the geometrical isomers gave the same products in the same ratio, except in the case of o-(β,γ-dimethylallyl)phenyl azide.Rearrangement by phenyl migrations occured with the β-phenylallyl compound. o-Allylphenyl azide (27a), (o-azidophenyl)acetaldehyde (27b), and o-phenyl azide (27c) required temperatures of 155-200 deg C for thermolysis and yielded 2-methylindole, oxindole, and 2-ethylbenzoxazole, respectively, by nitrene insertion.
- Smith, Peter A. S.,Chou, Shang-shing Peter
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p. 3970 - 3977
(2007/10/02)
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