- Phosphoric Acid Catalyzed 1,2-Rearrangements of 3-Hydroxyindolenines to Indoxyls and 2-Oxindoles: Reagent-Controlled Regioselectivity Enabled by Dual Activation
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A common synthetic route to indoxyl and 2-oxindole alkaloids utilizes the oxidation of indoles to 3-hydroxyindolenines, followed by acid-mediated 1,2-rearrangement. However, controlling the regioselectivity is often challenging and there is an ongoing need for new reaction conditions allowing to steer product selectivity. We report herein that phosphoric acids are ideal organocatalysts for the highly regioselective 1,2-rearrangement of 3-hydroxyindolenines to 2-oxindoles, with predictable product selectivity arising from an efficient dual activation mode.
- Schendera, Eva,Lerch, Stephanie,von Drathen, Thorsten,Unkel, Lisa-Natascha,Brasholz, Malte
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supporting information
p. 3134 - 3138
(2017/06/21)
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- Reaction of arynes with amino acid esters
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An efficient route to a variety of 2-phenylindolin-3-ones from amino acid methyl esters has been developed. The reaction of amino acid methyl esters with benzyne prepared from 2-(trimethylsilyl)phenyl triflate and CsF gave 2-phenylindolin-3-ones in moderate to good yields.
- Okuma, Kentaro,Matsunaga, Nahoko,Nagahora, Noriyoshi,Shioji, Kosei,Yokomori, Yoshinobu
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supporting information; experimental part
p. 5822 - 5824
(2011/06/23)
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- Alkylidenephosphoranes in heterocyclic synthesis: Reactivity of benzoxazinones with resonance-stabilized phosphorus ylides
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2H-3,1-Benzoxazine-2,4(1H)-dione and its N-methyl analogue react with alkylidenephosphoranes to give substituted quinolines and benzazepines as well as indanone and furan derivatives. Reaction mechanisms to explain the formation of products obtained are outlined. Georg Thieme Verlag Stuttgart.
- Kamel, Azza A.,Abdou, Wafaa M.
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p. 1269 - 1273
(2007/12/27)
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- Study of the addition of Grignard reagents to 2-aryl-3H-indol-3-ones
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Grignard reagents are added to the carbonyl group of 2-aryl-3H-indol-3-ones to generate 3-alkyl-(or phenyl)-2-aryl-3H-indol-3-ols, which are in turn rearranged to yield 2-alkyl(or phenyl)-2-aryl-1,2-dihydro-3H-indol-3-ones.
- Liu, Yahua,McWhorter Jr., William W.
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p. 2618 - 2622
(2007/10/03)
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- Heterocyclic 8?-Systems, 16 - Elimination Reactions of 2-Alkoxy-3-hydroxyindolines
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Thermolysis of 2-ethoxy-3-hydroxyindolines 1a - f affords oxindoles 3a - f as main products and the corresponding 3-indolinones 2a - f as by-products.The reaction course via indole 2,3-oxide intermediates is discussed.For this reason rearrangement reactio
- Beitzke, Bernhard,Schmidt, Richard R.
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p. 1726 - 1731
(2007/10/02)
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- Heterocyclic 8?-Systems, 15. Investigations on Indole 2,3-Oxides: Sythesis of 3-Hydroxyindoles via Intramolecular Wittig-Rearrangement of 1,2-Dihydro-4H-3,1-benzoxazines
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Investigations to trap indole 2,3-oxides 11 by base catalyzed ring contraction of 4H-3,1-benzoxazines 3 led in the system KNH2/NH3 to 3-hydroxy-3H-indoles 7.The N-methylbenzoxazinium salts 15, obtained from 3 and FSO3CH3, yielded with ethoxide under kinet
- Schmidt, Richard R.,Beitzke, Bernhard
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p. 2115 - 2135
(2007/10/02)
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- New Aspects in the Chlorination of Indoles with 1-Chlorobenzotriazole and 1-Chloroisatin
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2-Phenyl-, 1-methyl-2-phenyl-, and 2-phenyl-3-methylindole react with 1-chlorobenzotriazole and 1-chloroisatin to form essentially 3-chloroindoles.The composition of the products, which depends on the solvent used, suggests an electron-transfer process fo
- Berti, C.,Greci, L.,Andruzzi, R.,Trazza, A.
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p. 4895 - 4899
(2007/10/02)
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