- β-Amino alcohols from anilines and ethylene glycol through heterogeneous Borrowing Hydrogen reaction
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Borrowing Hydrogen (BH), also called Hydrogen Autotransfer (HA), reaction with neat ethylene glycol represents a key step in the preparation of β-amino alcohols. However, due to the stability of ethylene glycol, mono-activation has rarely been achieved. Herein, a combination of Pd/C and ZnO is reported as heterogeneous catalyst for this BH/HA reaction. This system results in an extremely air and moisture stable, and economic catalyst able to mono-functionalize ethylene glycol in water, without further activation of the diol. In this work, different diols and aromatic amines have been explored affording a new approach towards amino alcohols. This study reveals how the combination of two solid species can afford interesting catalytic properties in heterogeneous phase. ZnO activates ethylene glycol while Pd/C is the responsible of the BH/HA cycle. This catalytic system has also been found useful to dehydrogenate indoles affording indolines that undergo in situ BH/HA cycle prior to re-aromatization, representing a tandem heterogeneous process.
- Llabres-Campaner, Pedro J.,Ballesteros-Garrido, Rafael,Ballesteros, Rafael,Abarca, Belén
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supporting information
p. 5552 - 5561
(2017/08/22)
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- A simple two-step synthesis of indoles
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A two-step synthesis of indoles that is suitable for use on a large scale is described. The general applicability of this methodology has also been briefly explored.
- Walkington, Andrew,Gray, Matthew,Hossner, Frank,Kitteringham, John,Voyle, Martyn
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p. 2229 - 2233
(2007/10/03)
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- Ruthenium-catalyzed heteroannulation of anilines with alkanolammonium chlorides leading to indoles
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Anilines react with alkanolammonium chlorides in an aqueous medium (H2O-dioxane) at 180°C in the presence of a catalytic amount of a ruthenium catalyst together with SnCl2·2H2O to afford the corresponding indoles in moderate to good yields. Especially, when triisopropanolammonium chloride is employed to react with anilines, 2-methylindoles are formed regioselectively. The presence of SnCl2·2H2O is necessary for the effective formation of indoles. A reaction pathway involving alkanol group transfer from alkanolamines to anilines, N-alkylation of anilines by anilinoalkanols and heteroannulation of 1,2-dianilinoalkanes is proposed for this catalytic process.
- Cho, Chan Sik,Kim, Jin Hwang,Kim, Tae-Jeong,Shim, Sang Chul
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p. 3321 - 3329
(2007/10/03)
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- Ruthenium-catalyzed synthesis of indoles from anilines and trialkanolammonium chlorides in an aqueous medium
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Anilines react with trialkanolammonium chlorides in an aqueous medium (H2O-dioxane) at 180°C in the presence of a catalytic amount of ruthenium(III) chloride hydrate and triphenylphosphine together with tin(II) chloride dihydrate to afford the corresponding indoles in good yields. (C) 2000 Elsevier Science Ltd.
- Cho, Chan Sik,Kim, Jin Hwang,Shim, Sang Chul
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p. 1811 - 1814
(2007/10/03)
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- Ruthenium-catalysed synthesis of indoles from anilines and trialkanolamines in the presence of tin(II) chloride dihydrate
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Anilines react with trialkanolamines in dioxane in the presence of a catalytic amount of a ruthenium catalyst together with tin(II) chloride dihydrate to give the corresponding indoles in moderate to good yields.
- Cho, Chan Sik,Lim, Hyo Kyun,Shim, Sang Chul,Kim, Tae Jeong,Choi, Heung-Jin
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p. 995 - 996
(2007/10/03)
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- SYNTHESIS OF INDOLES FROM N-(TRIFLUOROACETYL)-2-ANILINO ACETALS
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N-(trifluoroacetyl)indoles (3) are produced in high yield from appropriately ring-substituted N-(trifluoroacetyl)-2-anilino acetals (2) in boiling trifluoroacetic acid containing excess trifluoroacetic anhydride.Mild saponification provides the free indoles nearly quantitatively.The scope of the reaction is discussed.The ring closure follows solvolytic substitution of a trifluoroacetoxy group for one of the ethoxy groups in 2.The method has been extended to cyclization of N-(trifluoroacetyl)-α-anilinoacetone in hot polyphosphoric acid followed by saponification to yield 3-methylindole.
- Nordlander, J. Eric,Catalane, David B.,Kotian, Kirtivan D.,Stevens, Randall M.,Haky, Jerome E.
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p. 778 - 782
(2007/10/02)
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- The Decomposition of β-Phenethylsulfonyl Azides. Solution Chemistry and Flash Vacuum Pyrolysis
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The intramolecular cyclization of the parent title compound and a number of para-substituted derivatives (1) in solution was found to take place in low yield and to be accompanied by products of intermolecular reactions, namely, C-H insertion (4) and hydrogen abstraction (3).The use of an excess of a relatively inert solvent Freon 113 led to a better yield of the desired 3,4-dihydro-2,1-benzothiazine 2,2-dioxides (2).Flash vacuum pyrolysis (FVP) of 1 at 250-300 deg C also gave some 2, but the use of higher temperatures led to the formation of styrenes (8), indolines (9), indoles (10), sulfur dioxide, and the remarkable transformation products, the 4-substituted 6,7-dihydro-5H-1-pyrindines (7), in good yield.The styrenes result from the elimination of HN3 and SO2 from the azides, and indolines are formed in good yield by FVP of 2 at 650 deg C.The dihydropyrindines are not obtained from 2, and β-phenethynitrene is not a source of any of the above observed products.A mechanism is proposed for the formation of 7 from β-arylethylsulfonylnitrenes.Consistent with the mechanism is the observation that both 1- and 2-phenylpropanesulfonyl azide give a mixture of 6- and 7-methyl-6,7-dihydro-5H-1-pyrindines in the same ratio on FVP at 650 deg C.Thermolysis of 1a in benzene at 100 deg C gives an N-sulfonylazepine derivative.The FVP of 1 and 2 at 650 deg C are preparative routes to 7 and 9, respectively.
- Abramovitch, Rudolph A.,Holcomb, William D.,Wake, Shigeo
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p. 1525 - 1533
(2007/10/02)
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