cas 16096-32-5, 4-Methylindole | Articles data

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Diaryliodonium Salt-Based Synthesis of N-Alkoxyindolines and Further Insights into the Ishikawa Indole Synthesis
A diaryliodonium salt-based strategy enabled the first systematic synthesis of rarely accessible N-alkoxyindolines. Mechanistic analyses suggested that the reaction likely involves reductive elimination of iodobenzene from iodaoxazepine via a four-membered transition state, followed by Meisenheimer rearrangement. Substrates with N-carbamate protection afforded indole in a manner similar to that of the Ishikawa indole synthesis. Preinstallation of a stannyl group as an iodonium salt precursor greatly expanded the substrate scope, and further mechanistic insights are discussed.
Ogura, Akihiro,Shibata, Kouhei,Takao, Ken-Ichi
p. 10067 - 10087
(2021/07/26)

Covalent Organic Frameworks toward Diverse Photocatalytic Aerobic Oxidations
Photoactive two-dimensional covalent organic frameworks (2D-COFs) have become promising heterogenous photocatalysts in visible-light-driven organic transformations. Herein, a visible-light-driven selective aerobic oxidation of various small organic molecules by using 2D-COFs as the photocatalyst was developed. In this protocol, due to the remarkable photocatalytic capability of hydrazone-based 2D-COF-1 on molecular oxygen activation, a wide range of amides, quinolones, heterocyclic compounds, and sulfoxides were obtained with high efficiency and excellent functional group tolerance under very mild reaction conditions. Furthermore, benefiting from the inherent advantage of heterogenous photocatalysis, prominent sustainability and easy photocatalyst recyclability, a drug molecule (modafinil) and an oxidized mustard gas simulant (2-chloroethyl ethyl sulfoxide) were selectively and easily obtained in scale-up reactions. Mechanistic investigations were conducted using radical quenching experiments and in situ ESR spectroscopy, all corroborating the proposed role of 2D-COF-1 in photocatalytic cycle.
Liu, Shuyang,Tian, Miao,Bu, Xiubin,Tian, Hua,Yang, Xiaobo
supporting information
p. 7738 - 7744
(2021/05/07)

Electron Transfer Photoredox Catalysis: Development of a Photoactivated Reductive Desulfonylation of an Aza-Heteroaromatic Ring
Herein, we report a protocol for desulfonylation of aza-heteroaromatic rings via photoinduced electron transfer and hydrogen atom transfer. This general protocol has a wide substrate range and moderate to good yields. The utility of the method was demonstrated by the chemoselective desulfonylation of a molecule containing both an aliphatic and an aromatic sulfonamide. (Figure presented.).
Qiang-Liu,Liu, Yu-Xiu,Song, Hong-Jian,Wang, Qing-Min
supporting information
p. 3110 - 3115
(2020/07/04)

Regioselective Formation of Substituted Indoles: Formal Synthesis of Lysergic Acid
A Diels–Alder reaction-based strategy for the synthesis of indoles and related heterocycles is reported. An intramolecular cycloaddition of alkyne-tethered 3-aminopyrones gives 4-substituted indolines in good yield and with complete regioselectivity. Additional substitution is readily tolerated in the transformation, allowing synthesis of complex and non-canonical substitution patterns. Oxidative conditions give the corresponding indoles. The strategy also allows the synthesis of carbazoles. The method was showcased in a formal synthesis of lysergic acid.
Beaudry, Christopher M.,Points, Gary L.,Stout, Kenneth T.
supporting information
p. 16655 - 16658
(2020/12/01)

DMSO/t-BuONa/O2-Mediated Aerobic Dehydrogenation of Saturated N-Heterocycles
Aromatic N-heterocycles such as quinolines, isoquinolines, and indolines are synthesized via sodium tert-butoxide-promoted oxidative dehydrogenation of the saturated heterocycles in DMSO solution. This reaction proceeds under mild reaction conditions and has a good functional group tolerance. Mechanistic studies suggest a radical pathway involving hydrogen abstraction of dimsyl radicals from the N-H bond or α-C-H of the substrates and subsequent oxidation of the nitrogen or α-aminoalkyl radicals.
Cai, Hu,Tan, Wei,Xie, Yongfa,Yang, Ruchun,Yue, Shusheng
p. 7501 - 7509
(2020/07/07)

Potassium tert-Butoxide-Promoted Acceptorless Dehydrogenation of N-Heterocycles
Potassium tert-butoxide-promoted acceptorless dehydrogenation of N-heterocycles was efficiently realized for the generation of N-heteroarenes and hydrogen gas under transition-metal-free conditions. In the presence of KOtBu base, a variety of six- and five-membered N-heterocyclic compounds efficiently underwent acceptorless dehydrogenation to afford the corresponding N-heteroarenes and H2 gas in o-xylene at 140 °C. The present protocol provides a convenient route to aromatic nitrogen-containing compounds and H2 gas. (Figure presented.).
Liu, Tingting,Wu, Kaikai,Wang, Liandi,Yu, Zhengkun
supporting information
p. 3958 - 3964
(2019/08/01)

A indole compound and its preparation method and application (by machine translation)
The invention discloses a indole compound and its preparation method and application. The indole compounds of the structural formula such as formula (I) is shown. The indoles, rice galenical demonstrate the excellent inhibitory activity, the effect of most of the compound is obviously better than the positive control drug validamycin; especially compound I - 43, I - 44, I - 54, I - 73, II - 7 and II - 17, its galenical very good living body protection and treating effect, effect is better than the positive control; more specifically, compound I - 43 of the rice sheath blight bacteriostatic activity than validamycin activity is improved by nearly 300 times. The indole compounds in the prevention and/or treatment of rice sheath blight has great application prospects. In addition the compound of the invention is simple in construction, the preparation method is simple, and is suitable for large-scale industrial production. (I). (by machine translation)
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Paragraph 0130; 0131

(2018/10/02)

Dehydrogenation of N-Heterocycles by Superoxide Ion Generated through Single-Electron Transfer
Nitrogen-containing heteroarene motifs are found in numerous pharmaceuticals, natural products, and synthetic materials. Although several elegant methods for synthesis of these compounds through dehydrogenation of the corresponding saturated heterocycles have been reported, some of the methods are hampered by long reaction times, harsh conditions, and the need for catalysts that are not readily available. This work reports a novel method for dehydrogenation of N-heterocycles. Specifically, O2.? generated in situ acts as the oxidant for N-heterocycle substrates that are susceptible to oxidation through a hydrogen atom transfer mechanism. This method provides a general, green route to N-heteroarenes.
Huang, Yuan-Qiong,Song, Hong-Jian,Liu, Yu-Xiu,Wang, Qing-Min
supporting information
p. 2065 - 2069
(2018/01/27)

Nickel-catalyzed methylation of aryl halides/tosylates with methyl tosylate
This work describes the cross-electrophile methylation of aryl bromides and aryl tosylates with methyl tosylate. The mild reaction conditions allow effective methylation of a wide set of heteroaryl electrophiles and dimethylation of dibromoarenes.
Wang, Jiawang,Zhao, Jianhong,Gong, Hegui
supporting information
p. 10180 - 10183
(2017/09/23)

β-Amino alcohols from anilines and ethylene glycol through heterogeneous Borrowing Hydrogen reaction
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
supporting information
p. 5552 - 5561
(2017/08/22)

Acceptorless Dehydrogenation of N-Heterocycles by Merging Visible-Light Photoredox Catalysis and Cobalt Catalysis
Herein, the first acceptorless dehydrogenation of tetrahydroquinolines (THQs), indolines, and other related N-heterocycles, by merging visible-light photoredox catalysis and cobalt catalysis at ambient temperature, is described. The potential applications to organic transformations and hydrogen-storage materials are demonstrated. Primary mechanistic investigations indicate that the catalytic cycle occurs predominantly by an oxidative quenching pathway.
He, Ke-Han,Tan, Fang-Fang,Zhou, Chao-Zheng,Zhou, Gui-Jiang,Yang, Xiao-Long,Li, Yang
supporting information
p. 3080 - 3084
(2017/03/14)

DERIVATIVES OF AZA ADAMANTANE AND USES THEREOF
The present invention relates to certain amide derivatives that have the ability to inhibit 11-β-hydroxysteroid dehydrogenase type 1 (11β-HSD-1) and which are therefore useful in the treatment of certain disorders that can be prevented or treated by inhibition of this enzyme. In addition the invention relates to the compounds, methods for their preparation, pharmaceutical compositions containing the compounds and the uses of these compounds in the treatment of certain disorders. It is expected that the compounds of the invention will find application in the treatment of conditions such as non-insulin dependent type 2 diabetes mellitus (NIDDM), insulin resistance, obesity, impaired fasting glucose, impaired glucose tolerance, lipid disorders such as dyslipidemia, hypertension and as well as other diseases and conditions.
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Paragraph 0271; 0272

(2015/05/26)

CYCLIC AMIDE DERIVATIVES AS INHIBITORS OF 11 - BETA - HYDROXYSTEROID DEHYDROGENASE AND USES THEREOF
The present invention relates to certain amide derivatives that have the ability to inhibit 11-β-hydroxysteroid dehydrogenase type 1 (11β-HSD-1) and which are therefore useful in the treatment of certain disorders that can be prevented or treated by inhibition of this enzyme. In addition the invention relates to the compounds, methods for their preparation, pharmaceutical compositions containing the compounds and the uses of these compounds in the treatment of certain disorders. It is expected that the compounds of the invention will find application in the treatment of conditions such as non-insulin dependent type 2 diabetes mellitus (NIDDM), insulin resistance, obesity, impaired fasting glucose, impaired glucose tolerance, lipid disorders such as dyslipidemia, hypertension and as well as other diseases and conditions.
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Paragraph 0339

(2015/06/17)

DERIVATIVES OF AZA ADAMANTANE AND USES THEREOF
The present invention relates to certain amide derivatives that have the ability to inhibit 11-β-hydroxysteroid dehydrogenase type 1 (11β-HSD-1) and which are therefore useful in the treatment of certain disorders that can be prevented or treated by inhibition of this enzyme. In addition the invention relates to the compounds, methods for their preparation, pharmaceutical compositions containing the compounds and the uses of these compounds in the treatment of certain disorders. It is expected that the compounds of the invention will find application in the treatment of conditions such as non-insulin dependent type 2 diabetes mellitus (NIDDM), insulin resistance, obesity, impaired fasting glucose, impaired glucose tolerance, lipid disorders such as dyslipidemia, hypertension and as well as other diseases and conditions.
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Page/Page column 79; 81

(2013/08/15)

CYCLIC AMIDE DERIVATIVES AS INHIBITORS OF 11 - BETA - HYDROXYSTEROID DEHYDROGENASE AND USES THEREOF
The present invention relates to certain amide derivatives that have the ability to inhibit 11-β-hydroxysteroid dehydrogenase type 1 (11β-HSD-1) and which are therefore useful in the treatment of certain disorders that can be prevented or treated by inhibition of this enzyme. In addition the invention relates to the compounds, methods for their preparation, pharmaceutical compositions containing the compounds and the uses of these compounds in the treatment of certain disorders. It is expected that the compounds of the invention will find application in the treatment of conditions such as non-insulin dependent type 2 diabetes mellitus (NIDDM), insulin resistance, obesity, impaired fasting glucose, impaired glucose tolerance, lipid disorders such as dyslipidemia, hypertension and as well as other diseases and conditions.
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Page/Page column 96

(2013/09/12)

Synthesis and biological activities of 4-trifluoromethylindole-3-acetic acid: A new fluorinated indole auxin
In our studies on the development of new promoters for the root formation of tree cuttings, 4-trifluoromethylindole-3-acetic acid (4-CF3-IAA), a new fluorinated auxin, was synthesized via 4-trifluoromethylindole and 4-trifluoromethylindole-3-acetonitrile by using 2-methyl-3-nitrobenzotrifluoride as the starting material. As a control compound for comparing biological activities, 4-methylindole-3-acetic acid (4-CH3-IAA) was also synthesized by using 2,3-dimethylnitrobenzene as the starting material. The biological activities of these compounds were compared by three bioassays with those of indole-3-acetic acid and 4-chloroindole-3-acetic acid (4-Cl-IAA), which, like 4-CF3-IAA and 4-CH3-IAA, has a substituent at the 4-position of the indole nucleus. 4-CF3-IAA showed strong root formation-promoting activity with black gram cuttings which was 1.5 times higher than that of 4-(3-indole)butyric acid at 1 × 10-4 M. 4-CH 3-IAA, however, only weakly promoted root formation in spite of its strong inhibition of hypocotyl growth in Chinese cabbage and promotion of hypocotyl swelling and lateral root formation in black gram. On the other hand, 4-CF3-IAA demonstrated weaker activities than 4-CH3-IAA and 4-Cl-IAA in these two bioassays.
Katayama, Masato,Masui, Yuko,Kageyama, Eiji,Kawabata, Youichi,Kanayama, Kozo
p. 2025 - 2033
(2008/12/22)

Benzimidazole derivative
The present invention is a thiobenzimidazole derivative represented by the following formula (1) or a medically acceptable salt thereof wherein said thiobenzimidazole derivative and a medically acceptable salt thereof have a potent activity of inhibiting human chymase. Thus, they are potential preventive and/or therapeutic agents clinically applicable to various diseases in which human chymase is involved.
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(2008/06/13)

Benzimidazole derivatives
A benzimidazole derivative or its medically acceptable salt, represented by the following formula (1), that is a human chymase activity inhibitor capable of being applied clinically: 1wherein, R1 and R2 represent a hydrogen atom, an alkyl group or an alkoxy group, etc., A represents an alkylene group or an alkenylene group, E represents —COOR3, —SO3R3, —CONHR3 or —SO2NHR3, etc., G represents an alkylene group, M represents a single bond or —S(O)m. J represents a heterocyclic group, and X represents —CH= or a nitrogen atom.
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Page 26

(2010/02/05)

BENZIMIDAZOLE DERIVATIVES
A benzimidazole derivative or its medically acceptable salt, represented by the following formula (1), that is a human chymase activity inhibitor capable of being applied clinically: wherein, R1 and R2 represent a hydrogen atom, an alkyl group or an alkoxy group, etc., A represents an alkylene group or an alkenylene group, E represents -COOR3, -SO3R3, -CONHR3 or -SO2NHR3, etc., G represents an alkylene group, M represents a single bond or -S(O)m-, J represents a heterocyclic group, and X represents -CH= or a nitrogen atom.
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(2008/06/13)

Total synthesis of indoles from Tricholoma species via Bartoli/heteroaryl radical methodologies
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Dobbs
p. 638 - 641
(2007/10/03)

Ruthenium-catalyzed heteroannulation of anilines with alkanolammonium chlorides leading to indoles
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
p. 3321 - 3329
(2007/10/03)

Ruthenium-catalyzed synthesis of indoles from anilines and trialkanolammonium chlorides in an aqueous medium
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
p. 1811 - 1814
(2007/10/03)

Ruthenium-catalysed synthesis of indoles from anilines and trialkanolamines in the presence of tin(II) chloride dihydrate
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
p. 995 - 996
(2007/10/03)

ANTIMIGRAINE 1,2,5-THIADIAZOLE DERIVATIVES OF INDOLYLALKYL-PYRIDNYL AND PYRIMIDINYLPIPERAZINES
A series of novel 5-(3,4-diamino-1,2,5-thiadiazole and S-oxide) derivatives of indolylalkylpiperazinyl pyridines and pyrimidines of Formula I are intended for use in the alleviation of vascular headaches. STR1 In Formula I, X is selected from S, SO and SO 2.
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(2008/06/13)

ANTIMIGRAINE CYCLOBUTENEDIONE DERIVATIVES OF INDOLYLALKYL-PYRIDINYL AND PYRIMIDINYLPIPERAZINES
A series of novel 5-cyclobutenedione derivatives of indolylalkylpiperazinyl pyridines and pyrimidines of Formula I are intended for use in the alleviation of vascular headaches. STR1
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(2008/06/13)

Indole- and benzimidazole-substituted imidazole and benzimidazole derivatives
Novel compounds are disclosed having the formula STR1 wherein X, R1, R2, R3, R4, and R5 are substituents. These compounds inhibit the action of angiotensin II and are useful, therefore, for example, as antihypertensive agents.
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(2008/06/13)

Pyrrole-2,3-quinodimethane Analogues in the Synthesis of Indoles. Part 2. Synthesis and Diels-Alder Reactions of 1,6-Dihydropyranopyrrol-6(1H)-ones
The pyranopyrrol-6-ones 7-9, 12 and 13 are stable cyclic analogues of pyrrole-2,3-quinodimethane, and undergo Diels-Alder reaction with a range of alkynes to give, after loss of carbon dioxide, indoles.
Andrews, John F. P.,Jackson, P. Mark,Moody, Christopher J.
p. 7353 - 7372
(2007/10/02)

Palladium-Catalyzed Coupling of 2-Bromoanilines with Vinylstannanes. A Regiocontrolled Synthesis of Substituted Indoles
The palladium-catalyzed cross-coupling reaction of aryl halides and triflates with vinylstannane reagents has been used to produce a variety of substituted indoles.The mild reaction conditions and selectivity inherent in the coupling reaction have been utilized to produce regiochemically pure 4-, 5-, and 6-substituted indoles.
Krolski, Michael E.,Renaldo, Alfred F.,Rudisill, Duane E.,Stille, J. K.
p. 1170 - 1176
(2007/10/02)

Simple Synthesis of Indoles and of Corresponding 3(2H)-Indolone Derivatives, Monosubstituted at the Benzene Ring, as Synthetic Precursors of Natural Compounds
Application of a specific BCl3-catalyzed ortho-chloroacetylation of the monosubstituted primary anilines 2a-e with chloroacetonitrile, as a variant of the Houben-Hoesch reaction, leads to the corresponding 2-amino-α-chloroacetophenones 3a-g.These may be reduced and cyclized to yield the indoles 4a-g or, after acylation to 5a-g and 7a, b converted by base-catalyzed dehydrochlorination into the 1-acyl-3(2H)-indolones 6a-g and 8a, b.
Nimtz, Manfred,Haefelinger, Guenter
p. 765 - 770
(2007/10/02)

Condensed Heteroaromatic Ring Systems. XII. Synthesis of Indole Derivatives from Ethyl 2-Bromocarbanilates
The palladium-catalyzed reaction of ethyl 2-bromocarbanilate with trimethylsilylacetylene yielded ethyl 2-(trimethylsilylethynyl)carbanilate, which was treated with sodium ethoxide to give indole.The carbanilates having a methyl or a bromo substituent were similarly transformed to corresponding indole derivatives.Furthermore, pyrrolo- and Pyrrolopyridines were synthesized by this method.Keywords---palladium-catalyzed reaction; trimethylsilylacetylene; ethyl 2-halocarbanilate; ethyl 2-halopyridinecarbamate; ethyl 2-(trimethylsilylethynyl)carbanylate; ethyl o-(trimethylsilylethynyl)pyridinecarbamate;indole;pyrrolopyridine
Sakamoto, Takao,Kondo, Yoshinori,Iwashita, Shigeki,Yamanaka, Hiroshi
p. 1823 - 1828
(2007/10/02)

TIN-THALL REACTION, A VERSATILE METHOD FOR CROSS COUPLING TIN COMPOUNDS WITH THALLIUM COMPOUNDS
A new cross coupling reaction between tin compounds and thallium compounds is developed and its versatility is demonstrated by the convenient synthesis of various 4-substituted indoles.KEYWORDS - tin-thall reaction; thallation-palladation; cross coupling; 4-substituted indole; thallium compound; tin compound; palladium acetate; 4-(3-pyridyl)-3-indolecarbaldehyde
Somei, Masanori,Yamada, Fumio,Naka, Katsumi
p. 1322 - 1326
(2007/10/02)

Condensed Heteroaromatic Ring Systems. VI. Synthesis of Indoles and Pyrrolopyridines from o-Nitroarylacetylenes
Catalytic hydrogenation of o-nitrophenylacetaldehyde diethyl acetal over palladium-carbon, followed by intramolecular cyclization of the resulting o-aminophenylacetaldehyde diethyl acetal with hydrochloric acid, gave indole.Similarly, 4-methylindole, ethyl 5-indolecarboxylate, and various pyrrolopyridines were synthesized from the corresponding o-nitroarylacetaldehyde derivatives.The preparation of the desired o-nitroarylacetaldehydes was accomplished by the condensation of o-halonitroaromatics with trimethylsilylacetylene in the presence of dichloro-bis(triphenylphosphine)palladium as a catalyst, followed by ethanolysis of the resulting o-(trimethylsilylethenyl)nitroaromatics.Keywords - o-halonitroaromatic; o-cyanohaloaromatic; trimethylsilylacetylene; palladium-catalyzed reaction; cyclization; indole; pyrrolopyridine
Sakamoto, Takao,Kondo, Yoshinori,Yamanaka, Hiroshi
p. 2362 - 2368
(2007/10/02)

Some Observations on the Formation of 1-Hydroxyindoles in the Leimgruber-Batcho Indole Synthesis
The factors influencing the formation of 1-hydroxyindoles in the catalytic hydrogenation of β-dimethylamino-2-nitrostyrenes (Leimgruber-Batcho indole synthesis) have been investigated.Significant amounts of 1-hydroxyindoles were obtained only when the β-dimethylamino-2-nitrostyrene was substituted with an electron-withdrawing group at the 5 or 6 position.The proportion of 1-hydroxyindole formed relative to the normal indole product was found to increase as both the amount of catalyst and hydrogen pressure were decreased.
Clark, Robin D.,Repke, David B.
p. 121 - 125
(2007/10/02)

Cyclization of 2-acetaldehyde Diethyl Acetals to Indoles. Evidence for Stereoelectronic Effects in Intramolecular Electrophilic Aromatic Substitution
Methanesulfonamides of N-(2,2-diethoxyethyl)anilines can be cyclized to indoles in aromatic solvents by reaction with titanium tetrachloride.The temperature of the cyclization is substituent dependent, occurring at 0 deg C for the m-methoxy derivative but requiring 130 deg C for the p-bromo compound.Yields are good for various alkoxy-, alkyl-, and haloindoles, ranging from 60percent to 90percent.Meta-substituted reactants give rise to mixtures of 4- and 6-substituted indoles in which the 6-substituted product dominates by 2-4:1.The cyclization fails for ortho-substituted reactants.The major reaction process is N-dealkylation in the case of ortho-substituted compounds.An analogous cyclization occurs with the methanesulfonamides of N-(3,3-diethoxypropyl)anilines to give 1-(methylsulfonyl)-4-chloro-1,2,3,4-tetrahydroquinolines.This cyclization is much more rapid than for the five-membered ring closure leading to indoles and indicates a substantial rate retardation due to stereoelectronic effects in the indole cyclization.Ortho substitution also prevents cyclization in the six-membered-ring case.
Sundberg, Richard J.,Laurino, Joseph P.
p. 249 - 254
(2007/10/02)

Synthesis of Substituted Indoles via Meerwein Arylation
A new method for the synthesis of substituted indoles is detailed.Meerwein arylation of 4- and 6-substituted 2-nitrobenzenediazonium chlorides with vinyl acetate or vinyl bromide and subsequent reductive cyclization of the resulting adducts affords the corresponding 6- and 4-substituted (CH3, OCH3, Cl, Br, CF3) indoles.The diazonium bisulfates of weakly basic 2-nitroanilines (4-Cl, 6-Br, 4-CF3) gave higher yields of Meerwein arylation adducts than the corresponding diazonium chlorides.Coupling of 2-nitrobenzenediazonium chloride with 2-acetoxy-1-alkenes followed byreductive cyclization affords 2-alkylindoles.
Raucher, Stanley,Koolpe, Gary A.
p. 2066 - 2069
(2007/10/02)

Processes for preparing 4-substituted indoles
A new chemical sequence for preparing indoles is disclosed whose key reactions are reaction of a o-nitrotoluene with tris(dimethylamino)methane to give a β-dimethylamino-o-nitrostyrene which is converted into a semicarbazone and cyclized.
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(2008/06/13)

SYNTHESIS OF INDOLES FROM N-(TRIFLUOROACETYL)-2-ANILINO ACETALS
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.
p. 778 - 782
(2007/10/02)

SYNTHESIS OF 4-SUBSTITUTED INDOLES FROM o-NITROTOLUENES
A facile two- or three-step transformation of o-nitrotoluenes into 4-substituted indoles is described.Treatment of o-nitrotoluenes 1 with DMF acetal, or sometimes more advantageously with tris(N,N-dimethylamino)methane, affords β-(N,N-dimethylamino)styrenes 2 which are readily converted too-nitrophenylacetaldehyde semicarbazones 3 without isolation.Reduction of either 2 or 3 affords 4-substituted indoles 4.Use of the very insoluble semicarbazones results in vastly superior yields of 4 by minimizing completing bimolecular condensation reactions during reduction.This new procedure has been applied to efficiently and conveniently prepare a series of 4-substituted indoles 4.
Kruse, Lawrence I.
p. 1119 - 1124
(2007/10/02)

Intermediates for indoles
Ortho-nitrotoluenes are condensed with formamide acetals to yield the corresponding otho-nitro-β-aminestyrenes which undergo cyclization upon reduction to yield indoles.
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(2008/06/13)