113,027 research outputs found
Iterative C−H Functionalization Leading to Multiple Amidations of Anilides
No full textPolyaminobenzenes were synthesized by the ruthenium-catalyzed iterative C−H amidation of anilides using dioxazolones as an amino source. This strategy could be implemented by the sequential activation of C−H bonds of formerly generated compounds by cascade chelation assistance of newly installed amide groups. Computational studies provided a rationale. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinhei118191sciescopu
Direct C-H amidation of benzoic acids to introduce meta- and para-amino groups by tandem decarboxylation
No full textThe Ir-catalyzed mild C-H amidation of benzoic acids with sulfonyl azides was developed to give reactions with high efficiency and functional-group compatibility. Subsequent protodecarboxylation of ortho-amidated benzoic acid products afforded meta- or para-substituted (N-sulfonyl)aniline derivatives, the latter being inaccessible by other C-H functionalization approaches. The decarboxylation step was compatible with the amidation conditions, enabling a convenient one-pot, two-step process. Without a trace: Carboxylic acids are used as traceless directing groups in the Ir-catalyzed direct C-H amidation of arenes with sulfonyl azides under mild conditions. The tandem protodecarboxylation of the ortho-amidated benzoic acid products afforded meta- or para-substituted (N-sulfonyl)anilines, which are difficult to obtain by other C-H functionalization approaches. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim149481sciescopu
Iridium-catalyzed direct C-H amidation with weakly coordinating carbonyl directing groups under mild conditions
No full textAn iridium-catalyzed direct C-H amidation of weakly coordinating substrates, in particular of those bearing ester and ketone groups, under very mild conditions has been developed. The observed high reaction efficiency was achieved by the combined use of acetic acid and lithium carbonate as additives. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.13413811sciescopu
Ruthenium-catalyzed direct C-H amidation of arenes including weakly coordinating aromatic ketones
No full textC-H activation: The ruthenium-catalyzed direct sp2 C-H amidation of arenes by using sulfonyl azides as the amino source is presented (see scheme). A wide range of substrates were readily amidated including arenes bearing weakly coordinating groups. Synthetic utility of the thus obtained products was demonstrated in the preparation of biologically active heterocycles. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.11211201sciescopu
Comparison of the Reactivities and Selectivities of Group9 [Cp*M-III] Catalysts in C-H Functionalization Reactions
No full textPentamethylcyclopentadienyl (Cp*)-based Group9 metal (Co, Rh, or Ir) catalysts have emerged as powerful tools for C-H functionalization reactions. Whilst a diverse range of organic transformations have been developed by using [Cp*M-III] catalysts, they have often exhibited orthogonal reactivities and varied selectivities that depended on the choice of the central metal atom. An understanding of the physicochemical properties of the metals, as well as of their reaction mechanisms, has led to significant expansion of the synthetic scope of C-H functionalization reactions. This Focus Review summarizes and discusses the comparative catalytic reactivities and selectivities of the [Cp*M-III] catalysts, with an emphasis on metal-dependent pathway-switching by considering the mechanistic rationale ⓒ 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinhei
Direct C-H amination of arenes with alkyl azides under rhodium catalysis
No full textNew horizons in the utility of azides: The rhodium-catalyzed intermolecular direct C-H amination of arenes with alkyl azides provides a convenient route to N-alkyl anilines (see scheme; DG=directing group). Alkyl azides with a wide range of functional groups reacted readily with various substrates, including benzamides, aromatic ketones, and flavones. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.11181201sciescopu
[Cu(NHC)]-Catalyzed C-H Allylation and Alkenylation of both Electron-Deficient and Electron-Rich (Hetero)arenes with Allyl Halides
No full textNew reactivity of a [Cu(NHC)] (NHC=N-heterocyclic carbene) catalyst is disclosed for the efficient C-H allylation of polyfluoroarenes using allyl halides in benzene at room temperature. The same catalyst system also promotes an isomerization-induced alkenylation of initially the generated allyl arenes when the reaction is run in tetrahydrofuran. Significantly, not only electron-deficient but also electron-rich (hetero)arenes undergo this double-bond migration process, thus leading to alkenylated products. The present system features mild reaction conditions, broad scope with respect to the arene substrates and allyl halide reactants, good functional-group tolerance, and high stereoselectivity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim125251sciescopu
Mechanism-Driven Approach To Develop a Mild and Versatile C-H Amidation through Ir-III Catalysis
No full textDescribed herein is a mechanism-based approach to develop a versatile C-H amidation protocol under Ir-III catalysis. Reaction kinetics of a key C-N coupling step with acyl azide and 1,4,2-dioxazol-5-one led us to conclude that dioxazolones are much more efficient in mediating the formation of a carbon-nitrogen bond from an iridacyclic intermediate. Computational analysis revealed that the origin of higher reactivity is asynchronous decarboxylation motion, which may facilitate the formation of Ir-imido species. Importantly, stoichiometric reactivity was successfully translated into catalytic activity with a broad range of substrates (18 different types), many of which are regarded as challenging to functionalize. Application of the new method enables late-stage functionalization of drug molecules
(c) 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim1561sciescopu
Comparative Catalytic Activity of Group 9 [Cp*M(III)] Complexes: Cobalt-Catalyzed C-H Amidation of Arenes with Dioxazolones as an Amidating Reagent
No full textA procedure for the [Cp*CoIII]-catalyzed direct
C¢H amidation of arenes with dioxazolone has been developed.
This reaction proceeds under straightforward and mild
conditions with a broad range of substrates, including anilides.
A comparative study on the catalytic activity of Group 9
[{Cp*MCl2}2] complexes revealed the unique efficiency of the
cobalt catalyst. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim11521531sciescopu
Sequential C−H Borylation and N-Demethylation of 1,1′-Biphenylamines: Alternative Route to Polycyclic BN-Heteroarenes
No full text© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Described herein is an unprecedented access to BN-polyaromatic compounds from 1,1′-biphenylamines by sequential borane-mediated C(sp 2 )−H borylation and intramolecular N-demethylation. The conveniently in situ generated Piers’ borane from a borinic acid reacts with a series of N,N-dimethyl-1,1′-biphenyl-2-amines in the presence of PhSiH 3 to afford six-membered amine-borane adducts bearing a C(sp 2 )−B bond at the C2′-position. These species undergo an intramolecular N-demethylation with a B(C 6 F 5 ) 3 catalyst to provide BN-isosteres of polyaromatics. According to computational studies, a stepwise ionic pathway is suggested. Photophysical characters of the resultant BN-heteroarenes shown them to be distinctive from those of all-carbon analogues ⓒ 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinhei
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