- Direct Synthesis of Indoles from Azoarenes and Ketones with Bis(neopentylglycolato)diboron Using 4,4′-Bipyridyl as an Organocatalyst
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Multifunctionalized indole derivatives were prepared by reducing azoarenes in the presence of ketones and bis(neopentylglycolato)diboron (B2nep2) with a catalytic amount of 4,4′-bipyridyl under neutral reaction conditions, where 4,4′-bipyridyl acted as an organocatalyst to activate the B-B bond of B2nep2 and form N,N′-diboryl-1,2-diarylhydrazines as key intermediates. Further reaction of N,N′-diboryl-1,2-diarylhydrazines with ketones afforded N-vinyl-1,2-diarylhydrazines, which rearranged to the corresponding indoles via the Fischer indole mechanism. This organocatalytic system was applied to diverse alkyl cyclic ketones, dialkyl, and alkyl/aryl ketones, including heteroatoms. Methyl alkyl ketones gave the corresponding 2-methyl-3-substituted indoles in a regioselective manner. This protocol allowed us to expand the preparation of indoles having high compatibility with not only electron-donating and electron-withdrawing groups but also N- and O-protecting functional groups.
- Misal Castro, Luis C.,Sultan, Ibrahim,Nishi, Kohei,Tsurugi, Hayato,Mashima, Kazushi
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p. 3287 - 3299
(2021/03/01)
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- Annulation of Indoles with 1,n-Dibromoalkanes by a Pd(II)-Catalyzed and Norbornene-Mediated Reaction Cascade
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Employing 1,3-dibromopropane, 1,4-dibromobutane, and 1,5-dibromopentane as biselectrophiles, the annulation of indoles was probed in the presence of PdCl 2 (MeCN) 2 as a catalyst and norbornene as a transpositional ligand. Ring formation to a five-membered ring was observed at positions C2 and N, while annulation of a six-membered ring occurred at positions C2 and C3. The latter cascade process was successfully applied to the direct synthesis of 1,2,3,4-tetrahydrocarbazoles from indoles (11 examples, 31-68% yield). Seven-membered-ring annulation was feasible by an initial coupling at positon C2 followed by alkylation at C3.
- Bach, Thorsten,Henkel, Michael
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p. 1231 - 1238
(2020/04/15)
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- Catalytic Oxidative Coupling Cyclization for Construction of Benzofuroindolenines under Mild Reaction Conditions
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We describe iron-catalyzed oxidative coupling cyclization of tetrahydrocarbazoles or THβCs or THγCs to form benzofuroindolenines as fused polycyclic indoles. This mild, efficient and simple approach afforded a library of more than 52 complex compounds across a range of substrate classes with good to excellent yields. (Figure presented.).
- Lin, Yuqi,Ye, Jinxiang,Zhang, Wenting,Gao, Yu,Chen, Haijun
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supporting information
p. 432 - 435
(2018/12/13)
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- A microwave-assisted, propylphosphonic anhydride (T3P) mediated one-pot Fischer indole synthesis
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A rapid, mild, and high yielding protocol for the Fischer indolization of arylhydrazines with T3P under microwave irradiation is described. Significant features of this method include short reaction times and preparative ease.
- Desroses, Matthieu,Wieckowski, Krzysztof,Stevens, Marc,Odell, Luke R.
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supporting information; experimental part
p. 4417 - 4420
(2011/09/19)
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- Methods and compositions
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Compounds, compositions and methods relating to kinesin inhibition are described herein.
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Page/Page column 14
(2009/07/17)
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- Regioselective electrophilic trifluoromethylation of indolines, oxindoles and indoles in superacid
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Treatment of indolines and N-acylindoles with HF/SbF5/CCl 4 yields 6-trifluoro derivatives (indole numbering) whereas indoles and oxindoles give the 5-trifluoro derivatives in good yield.
- Debarge, Sébastien,Kassou, Kenza,Carreyre, Hélène,Violeau, Bruno,Jouannetaud, Marie-Paule,Jacquesy, Jean-Claude
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- Traceless Fischer indole synthesis on the solid phase
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The Fischer indole synthesis using polymer-bound hydrazines is employed as the key step for the development of a traceless indole synthesis on a solid support.
- Rosenbaum, Claudia,Katzka, Catherine,Marzinzik, Andreas,Waldmann, Herbert
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p. 1822 - 1823
(2007/10/03)
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