16036-21-8Relevant articles and documents
1,4,2-Dioxazol-5-ones as Isocyanate Equivalents: Chemoselective Non-Metal-Catalyzed Carboxamidation of Indoles
Vala, Anand,Parmar, Deepa,Rayani, Rahul,Kusurkar, Rakesh,Guduru, Ramakrishna,Kaneriya, Uttam,Gondaliya, Uday,Parmar, Nirali,Soni, Jigar Y.
, (2022/02/21)
1,4,2-Dioxazol-5-ones are known to undergo decarboxylation under thermal conditions followed by Lossen s rearrangement to give isocyanates. Described herein is the in situ trapping of the isocyanates by indoles to give indole-3-carboxamides in good to exc
Well-Defined Dinuclear Gold Complexes for Preorganization-Induced Selective Dual Gold Catalysis
Vreeken, Vincent,Broere, Dani?l L. J.,Jans, Anne C. H.,Lankelma, Marianne,Reek, Joost N. H.,Siegler, Maxime A.,van der Vlugt, Jarl Ivar
supporting information, p. 10042 - 10046 (2016/08/16)
The synthesis, reactivity, and potential of well-defined dinuclear gold complexes as precursors for dual gold catalysis are explored. Using the preorganizing abilities of the ditopic PNHPiPr(LH) ligand, dinuclear AuI–AuIcomplex 1 and mixed-valent AuI–AuIIIcomplex 2 provide access to structurally characterized chlorido-bridged cationic species 3 and 4 upon halide abstraction. For 2, this transformation involves unprecedented two-electron oxidation of the redox-active ligand, generating a highly rigidified environment for the Au2core. Facile reaction with phenylacetylene affords the σ,π-activated phenylacetylide complex 5. When applied in the dual gold heterocycloaddition of a urea-functionalized alkyne, well-defined precatalyst 3 provides high regioselectivities for the anti-Markovnikov product, even at low catalyst loadings, and outperforms common mononuclear AuIsystems. This proof-of-concept demonstrates the benefit of preorganization of two gold centers to enforce selective non-classical σ,π-activation with bifunctional substrates.
Highly stereoselective ruthenium(II)-catalyzed direct C2- syn -alkenylation of indoles with alkynes
Zhang, Wei,Wei, Jun,Fu, Shaomin,Lin, Dongen,Jiang, Huanfeng,Zeng, Wei
supporting information, p. 1349 - 1352 (2015/03/30)
A carboamide-directed ruthenium-catalyzed C2-hydroindolation of alkynes has been described. This transformation provides a rapid access to free (N-H) C2-syn-alkenylated indole derivatives with the assistance of copper(II) salts, in which the directing group is removed via a one-pot process.
Competitive gold-activation modes in terminal alkynes: An experimental and mechanistic study
Gimeno, Ana,Cuenca, Ana B.,Suarez-Pantiga, Samuel,De Arellano, Carmen Ramirez,Medio-Simon, Mercedes,Asensio, Gregorio
, p. 683 - 688 (2014/01/23)
The competition between π- and dual σ,π-gold-activation modes is revealed in the gold(I)-catalyzed heterocyclization of 1-(o-ethynylaryl)urea. A noticeable effect of various ligands in gold complexes on the choice of these activation modes is described. The cationic [Au(IPr)]+ (IPr=2,6-bis(diisopropylphenyl)imidazol-2-ylidene) complex cleanly promotes the π activation of terminal alkynes, whereas [Au(PtBu3)]+ favors intermediate σ,π species. In this experimental and mechanistic study, which includes kinetic and cross-over experiments, several σ-gold, σ,π-gold, and other gold polynuclear reaction intermediates have been isolated and identified by NMR spectroscopy, X-ray diffraction, or MALDI spectrometry. The ligand control in the simultaneous or alternative π- and σ,π-activation modes is also supported by deuterium-labeling experiments. Copyright
AlMe3-mediated regio- and chemoselective reactions of indole with carbamoyl electrophiles
Velavan,Sumathi,Balasubramanian
, p. 3148 - 3157 (2013/06/27)
Herein, we report the regio- and chemoselective reactions of indole with carbamoyl electrophiles in presence of AlMe3. Indole-3-carboxamide was prepared in one-step from a reaction of indole with tertiary carbamoylimidazole in the presence AlMe
NHC-stabilized gold(I) complexes: Suitable catalysts for 6-exo-dig heterocyclization of 1-(o-Ethynylaryl)ureas
Gimeno, Ana,Medio-Simon, Mercedes,De Arellano, Carmen Ramirez,Asensio, Gregorio,Cuenca, Ana B.
supporting information; scheme or table, p. 1900 - 1903 (2010/06/21)
Figure presented 3-substituted 1-(o-ethynylaryl)ureas 1 selectively undergo either 6-exo-dig or 5-endo-dig cyclization (to give 4-methylene-3,4-quinazolin- 2-ones 2 or indoles 3, respectively) depending on the choice of the metal, ligand, and reaction conditions. The best results (up to 96% yield) in the preparation of the hydroamination products 2 are achieved with the highly bulky NHC-stabilized cationic gold(I) complex [Au(IPr)]+. Conversely, ureas bearing an internal alkyne lead to the 5-endo-dig cyclization mode regardless of the gold(I) complex employed. Whereas the nature of the substituent at N-3 does not have any influence on the regiochemistry observed, it does, in some cases, affect the efficiency of these transformations.
