3469-20-3Relevant articles and documents
The first regioselective palladium-catalyzed indolization of 2-bromo- or 2-chloroanilines with internal alkynes: A new approach to 2,3-disubstituted indoles
Shen, Ming,Li, Guisheng,Lu, Bruce Z.,Hossain, Azad,Roschangar, Frank,Farina, Vittorio,Senanayake, Chris H.
, p. 4129 - 4132 (2004)
(Chemical Equation Presented) The first practical and economical process for synthesis of 2,3-disubstituted indole compounds has been developed with high regioselectivity by palladium-catalyzed indolization of 2-bromo- or chloroanilines and their derivatives with internal alkynes.
2,3-Disubstituted indoles through the palladium-catalyzed reaction of aryl chlorides with o-alkynyltrifluoroacetanilides
Cacchi, Sandro,Fabrizi, Giancarlo,Goggiamani, Antonella
, p. 1301 - 1305 (2006)
2,3-Disubstituted indoles can be prepared in moderate to excellent yields by reacting readily available o-alkynyltrifluoroacetanilides with aryl chlorides in MeCN at 120°C in the presence of Pd2(dba)3 and Xphos.
Rhodium(I)-catalyzed Addition of Tolane to Azobenzene: A New Route to Indole Derivatives
Reisser, P.,Wakatsuki, Y.,Kisch, H.
, p. 1 - 12 (1995)
RhCl(PPh3)3 catalyzes the formation of N-anilino-2,3-diphenylindole (1) and small amounts of 2,3-diphenylindole (2) from azobenzene and diphenylacetylene.Weak acids or silica gel accelerate the reaction and induce an almost quantitative conversion to 1.Other rhodium(I) complexes are less active while rhodium(III) compounds inhibit the reaction.A preliminary reaction mechanism of the homogeneous catalysis is proposed and the structure of two key intermediates is substantiated by ab initio MO calculations. - Keywords: Azobenzene; Diphenylacetylene; Indoles; Rhodium(I)-catalysis; Silica gel supported catalysis.
Annulation of internal alkynes through a hydroamination/aza-Heck reaction sequence for the regioselective synthesis of indoles
Ackermann, Lutz,Sandmann, René,Villar, Amparo,Kaspar, Ludwig T.
, p. 769 - 777 (2008)
Highly regioselective annulation reactions of unsymmetrically substituted alkynes by primary 2-bromo or 2-chloroanilines are achieved with an efficient one-pot protocol, which relies on a regioselective TiCl4-catalyzed intermolecular hydroamination and a subsequent palladium-catalyzed intramolecular aza-Heck reaction. The use of unsymmetrically substituted alkynes in this strategy enables the synthesis of diversely functionalized indoles, with a regioselectivity that is complementary to the one obtained when employing Larock's annulation reaction.
Synthesis of indolo[2,1-a]isoquinolines via a triazene-directed C-H annulation cascade
Sun, Huan,Wang, Chengming,Yang, Yun-Fang,Chen, Ping,Wu, Yun-Dong,Zhang, Xinhao,Huang, Yong
, p. 11863 - 11872 (2014)
(Chemical Equation Presented) Indole-containing polyaromatic scaffolds are widely found in natural products, pharmaceutical agents, and π-conjugated functional materials. Often, the synthesis of these highly valuable molecules requires a multistep sequence. Therefore, a simple, one-step protocol to access libraries of polyaromatic indole scaffolds is highly desirable. Herein we describe the direct synthesis of polysubstituted indolo[2,1-a]isoquinoline analogues via a double C-H annulation cascade using triazene as an internally cleavable directing group. Evidence from HRMS and theoretical calculations suggests that an unprecedented 1,2-alkyl migration might be responsible for the in situ cleavage of the directing group. Both kinetic isotope effects and DFT calculations suggested that the alkyne insertion step is rate-limiting for the second C,N annulation reaction.
Transition Metal Complexes of Diazenes XXXVI [1a]: Formation of Indoles from Azobenzene and Diphenylacetylene through Supported Aqueous Phase Catalysis by Rhodium(I) Complexes
Westernacher,Kisch
, p. 469 - 473 (1996)
A SiO2 supported Rh(I) catalyst of trisulfonated triphenylphosphine catalyzes the addition of diphenylacetylene to azobenzene in refluxing butanol in the presence of triphenylphosphine to afford N-anilino-2,3-diphenylindole and 2,3-diphenylindole with turnover numbers of 80 and 20, respectively. As compared to the known homogeneous or heterogeneous (SiO2) catalysis by RhCl(PPh3)3, the supported aqueous phase system retains a constant turnover frequency throughout the reaction and can be partially recycled.
Rh(III)-catalyzed coupling of nitrones with alkynes for the synthesis of indolines
Kong, Lingheng,Xie, Fang,Yu, Songjie,Qi, Zisong,Li, Xingwei
, p. 925 - 932 (2015)
Rh-catalyzed redox-neutral coupling between N-aryl nitrones and alkynes has been achieved under relatively mild conditions. The reaction proceeded via C-H activation at the N-aryl ring with subsequent O-atom transfer, affording trisubstituted indolines in good chemoselectivity and moderate to good diasteroselectivity.
Uebergangsmetallkomplexe von Diazenen. XXXI. Orthometallierte Diazenkomplexe von Molybdaen, Eisen und Ruthenium: Struktur und Umsetzung zu 2,3-Diphenylindol
Garn, Dieter,Knoch, Falk,Kisch, Horst
, p. 155 - 164 (1993)
Irradiation of *Ru(CO)2>2 or Cp*Ru(CO)2CH3 (Cp* = C5Me5) in the presence of azobenzene or 4,4'-dimethylazobenzene affords orthometallated Cp*Ru(pap)(CO) (pap = (phenylazo)phenyl) and Cp*Ru(4,4'-dmp
Chiral-Phosphoric-Acid-Catalyzed C6-Selective Pictet-Spengler Reactions for Construction of Polycyclic Indoles Containing Spiro Quaternary Stereocenters
Huang, Wen-Jun,Wang, Han,Wang, Xin-Wei,Wu, Bo,Zhou, Yong-Gui
supporting information, p. 1727 - 1731 (2022/03/14)
Compared with the well-established asymmetric Pictet-Spengler reactions on the pyrrole ring of indoles, the catalytic asymmetric Pictet-Spengler reaction on the benzene ring of indoles has been rarely studied. Herein the C6-selective Pictet-Spengler react
Rhodium-Catalyzed Annulation of N-Acetoxyacetanilide with Substituted Alkynes: Conversion of Nitroarenes to Substituted Indoles
Ghorai, Jayanta,Ramachandran, Kuppan,Anbarasan, Pazhamalai
, p. 14812 - 14825 (2021/10/25)
A general and efficient rhodium-catalyzed redox-neutral annulation of N-acetoxyacetanilides, readily accessible from nitroarenes, with alkynes has been accomplished for the synthesis of substituted indole derivatives. A wide range of substituted 2,3-diarylindoles were achieved from various substituted N-acetoxyacetanilides and symmetrical/unsymmetrical alkynes in good to excellent yields. The developed method was successfully integrated with the synthesis of N-acetoxyacetanilides for the efficient one-pot synthesis of indoles from nitroarenes. The important features are the introduction of N-acetoxyacetamide as a new directing group, redox-neutral annulation, an additive-free approach, wide functional group tolerance, an intramolecular version, and a one-pot reaction of nitroarenes. The method was further extended to the synthesis of potent higher analogues of indole, viz., pyrrolo[3,2-f]indoles and dibenzo[a,c]carbazoles. In addition, a plausible mechanism was proposed based on the isolation and stoichiometric study of a potential aryl-Rh intermediate.
