- 1,4-pentadienyl-3-sulfonamides: frameworks for disfavored radical cascade cyclizations.
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[reaction: see text]. 1,4-pentadienyl-3-sulfonamides afford products including those resulting from disfavored 5-endo-trig reactions when subjected to radical cyclization conditions. Products resulting from pathways featuring 4-exo-trig cyclizations are also detected, even when the 4-exo-trig reaction leads to a highly strained bicyclo[3.2.0] ring system.
- Bommezijn,Martin,Kennedy,Lizos,Murphy
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Read Online
- An efficient two-step synthesis of 3-allylindoles
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A two-step synthetic sequence for an efficient synthesis of 3-allylindoles is described.
- Kulkarni, Mukund G.,Davawala, Saryu I.,Dhondge, Attrimuni P.,Gaikwad, Dnyaneshwar D.,Borhade, Ajit S.,Chavhan, Sanjay W.
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- Sodium Perborate: A Facile Catalyst for Allylation of Active Centers
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An efficient and ecofriendly allylation of O-H, N-H, and C-H groups has been achieved successfully with the reaction of allyl bromide by using sodium perborate as a new catalyst in aqueous media. The advantage of this method is operationally simple, short reaction time, good yield, and simple workup conditions over the previously reported conventional methods such as amination, oxyalkylation reactions of allyl bromide, and Friedel-Crafts allylation chemistry.
- Jayaprakash, Soora Harinath,Krishna, Balam Satheesh,Prasad, Sthanikam Siva,Sudha, Sarva Santhi,Reddy, Cirandur Suresh
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Read Online
- Pd-catalyzed C3-selective allylation of indoles with allyl alcohols promoted by triethylborane
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Under palladium catalysis, Et3B nicely promotes allyl alcohols to undergo C3-selective allylation of indoles and tryptophan; the yields range 75-95%. Copyright
- Kimura, Masanari,Futamata, Makoto,Mukai, Ryutaro,Tamaru, Yoshinao
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Read Online
- Zinc-mediated Barbier reactions of pyrrole and indoles: A new method for the alkylation of pyrrole and indoles
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Pyrrole and indoles react smoothly with alkyl halides such as allyl bromide, prenyl bromide, crotyl bromide and propargyl bromide in the presence of zinc metal in THF to afford the corresponding 3- and 2-alkyl pyrrole and 3-alkyl indole derivatives in good yields with high regioselectivity.
- Yadav,Reddy,Reddy, P.Muralikrishna,Srinivas
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Read Online
- Rapid Assembly of Functionalised Spirocyclic Indolines by Palladium-Catalysed Dearomatising Diallylation of Indoles with Allyl Acetate
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Herein, we report the application of allyl acetate to the palladium-catalysed dearomatising diallylation of indoles. The reaction can be carried out by using a readily available palladium catalyst at room temperature, and can be applied to a wide range of substituted indoles to provide access to the corresponding 3,3-diallylindolinines. These compounds are versatile synthetic intermediates that readily undergo Ugi reactions or proline-catalysed asymmetric Mannich reactions. Alternatively, acylation of the 3,3-diallylindolinines with an acid chloride or a chloroformate, followed by treatment with aluminium chloride, enables 2,3-diallylindoles to be prepared. By using ring-closing metathesis, functionalised spirocyclic indoline scaffolds can be accessed from the Ugi products, and a dihydrocarbazole can be prepared from the corresponding 2,3-diallylindole.
- Dhankher, Persis,Benhamou, Laure,Sheppard, Tom D.
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Read Online
- Synthesis of allyl cyanamides and N-cyanoindoles via the palladium-catalyzed three-component coupling reaction
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The palladium-catalyzed three-component coupling reaction (TCCR) of aryl isocyanides, allyl methyl carbonate, and trimethylsilyl azide was conducted in the presence of Pd2(dba)3·CHCl3 (2.5 mol %) and dppe (1,2-bis(diphenyl
- Kamijo, Shin,Yamamoto, Yoshinori
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Read Online
- A Combined Tamaru Allylation/Olefin Cross-Metathesis Approach for the Total Syntheses of (±)-Paniculidine B, (±)-Paniculidine C, and 2-Methylcarbazole
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A concise approach to the total syntheses of racemic paniculidines B and C is described. The route features a combined Tamaru allylation/olefin cross-metathesis sequence for the regiocontrolled synthesis of prenylindole intermediates. In addition, we report a transformation of the prenylated indole into 2-methylcarbazole catalyzed by sulfonic acid-functionalized silica gel.
- Tseng, Yi-Lun,Liang, Min-Chieh,Chen, I-Chia,Wu, Yen-Ku
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Read Online
- Alkene synthesis by photocatalytic chemoenzymatically compatible dehydrodecarboxylation of carboxylic acids and biomass
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Direct conversion of renewable biomass and bioderived chemicals to valuable synthetic intermediates for organic synthesis and materials science applications by means of mild and chemoselective catalytic methods has largely remained elusive. Development of artificial catalytic systems that are compatible with enzymatic reactions provides a synergistic solution to this enduring challenge by leveraging previously unachievable reactivity and selectivity modes. We report herein a dual catalytic dehydrodecarboxylation reaction that is enabled by a crossover of the photoinduced acridine-catalyzed O-H hydrogen atom transfer (HAT) and cobaloxime-catalyzed C-H-HAT processes. The reaction produces a variety of alkenes from readily available carboxylic acids. The reaction can be embedded in a scalable triple-catalytic cooperative chemoenzymatic lipase-acridine-cobaloxime process that allows for direct conversion of plant oils and biomass to long-chain terminal alkenes, precursors to bioderived polymers.
- Nguyen, Vu T.,Nguyen, Viet D.,Haug, Graham C.,Dang, Hang T.,Jin, Shengfei,Li, Zhiliang,Flores-Hansen, Carsten,Benavides, Brenda S.,Arman, Hadi D.,Larionov, Oleg V.
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p. 9485 - 9498
(2019/10/11)
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- Diastereoselective Allylation of Aldehydes by Dual Photoredox and Chromium Catalysis
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Herein, we report the redox-neutral allylation of aldehydes with readily available electron-rich allyl (hetero-) arenes, β-alkyl styrenes and allyl-diarylamines. This process was enabled by the combination of photoredox and chromium catalysis, which allowed a range of homoallylic alcohols to be prepared with high levels of selectivity for the anti diastereomer. Mechanistic investigations support the formation of an allyl chromium intermediate from allylic C(sp3)-H bonds and thus significantly extends the scope of the venerable Nozaki-Hiyama-Kishi reaction.
- Schwarz, J. Luca,Sch?fers, Felix,Tlahuext-Aca, Adrian,Lückemeier, Lukas,Glorius, Frank
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supporting information
p. 12705 - 12709
(2018/10/09)
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- Preparation method of 3-substituted oxidized indole and derivative
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The invention belongs to the technical field of organic chemistry and pharmaceutical chemistry and particularly relates to a method of preparing 3-substituted oxidized indole and a derivative. In themethod, with a 3-substituted indole derivative as a raw material and one or more of a tetrabutyl ammonium halide compound/sodium chloride/sodium iodide/potassium iodide as additives, and one or more of dichloromethane/1,2-dichloroethane/tetrahydrofurane/methylbenzene/1,4-dioxane/ethyl acetate/methanol are added as solvents; then one or more of [bis(trifluoroacetoxyl)iodine]benzene/iodosobenzene diacetate are added as oxidants in order to carry out a reaction with reaction temperature being controlled, thus producing the 3-substituted oxidized indole derivative. The method has gentle reaction conditions, simple operations, short reaction time and high yield, and is free of a metal catalyst and is environment-friendly.
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Paragraph 0053; 0055
(2018/06/26)
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- Total Synthesis of Isodihydrokoumine, (19 Z)-Taberpsychine, and (4 R)-Isodihydroukoumine N4-Oxide
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We report the total synthesis of the natural products isodihydrokoumine and (19Z)-taberpsychine in 11 steps each and (4R)-isodihydrokoumine N4-oxide in 12 steps from commercially available starting materials. The key reactions include an intramolecular [3 + 2] nitrone cycloaddition and Lewis acid mediated cyclizations of a common intermediate to provide the core structures of either taberpsychine or isodihydrokoumine.
- Kerkovius, Jeff K.,Kerr, Michael A.
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supporting information
p. 8415 - 8419
(2018/07/05)
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- Catalytic Oxidative Trifluoromethoxylation of Allylic C?H Bonds Using a Palladium Catalyst
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A catalytic intermolecular allylic C?H trifluoromethoxylation reaction of alkenes has been developed based on the use of a palladium catalyst, CsOCF3 as the trifluoromethoxide source, and benzoquinone as the oxidant. This reaction provides an efficient route for directly accessing allylic trifluoromethoxy derivatives with excellent regioselectivities from terminal alkenes via an allylic C?H bond activation process.
- Qi, Xiaoxu,Chen, Pinhong,Liu, Guosheng
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supporting information
p. 9517 - 9521
(2017/08/01)
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- Method for synthesizing 3-hydroxyl oxoindole derivative
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The invention discloses a method for synthesizing a 3-hydroxyl oxoindole derivative. The synthetic route is as shown in the specification, wherein R1 is methyl, ethyl, propyl, butyl, isopropyl, cyclohexyl, allyl, benzyloxyethyl or n-butyric acid methyl ester; a substituent R2 is methyl, methoxy, benzyloxy, fluorine, chlorine or bromine; and a substituent R3 is methyl, bromine or phenyl. The synthetic process comprises the following steps: dissolving a compound I and iodobenzene diacetate in acetic acid and reacting completely at 40-100 DEG C, and postprocessing and purifying to obtain a product II. The raw materials used in the method are easy to prepare, and iodobenzene diacetate can be sold in the market; there is no need to use a catalyst such as a metal catalyst or an organic catalyst, and cost is reduced and the method is environment-friendly.
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Paragraph 0332; 0333; 0334; 0335
(2017/06/02)
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- Regioselective N-allylation and N-cinnamylation of indoles using CuI-exchanged hierarchical nanoporous material
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Regioselective N-allylation and N-cinnamylation of indoles are achieved using a novel catalyst of CuI-exchanged hierarchically architectured nanoporous material (MMZCuIY). The catalyst was characterized by electron microscopy and X-ray methods. Other advantages like functional tolerance, easy separation and reusability of the catalyst are also highlighted.
- Senthilkumar,Kumarraja
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supporting information
p. 86 - 89
(2015/08/24)
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- Fluorination Patterning: A Study of Structural Motifs That Impact Physicochemical Properties of Relevance to Drug Discovery
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The synthesis of a collection of 3-substituted indole derivatives incorporating partially fluorinated n-propyl and n-butyl groups is described along with an in-depth study of the effects of various fluorination patterns on their properties, such as lipophilicity, aqueous solubility, and metabolic stability. The experimental observations confirm predictions of a marked lipophilicity decrease imparted by a vic-difluoro unit when compared to the gem-difluoro counterparts. The data involving the comparison of the two substitution patterns is expected to benefit molecular design in medicinal chemistry and, more broadly, in life as well as materials sciences.
- Huchet, Quentin A.,Kuhn, Bernd,Wagner, Bj?rn,Kratochwil, Nicole A.,Fischer, Holger,Kansy, Manfred,Zimmerli, Daniel,Carreira, Erick M.,Müller, Klaus
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p. 9041 - 9060
(2015/12/08)
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- Dearomative Indole (3 + 2) Reactions with Azaoxyallyl Cations - New Method for the Synthesis of Pyrroloindolines
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Herein, we report the first examples of the synthesis of pyrroloindolines by means of (3 + 2) dearomative annulation reactions between 3-substituted indoles and highly reactive azaoxyallyl cations. Computational studies using density functional theory (DFT) (B3LYP-D3/6-311G++) support a stepwise reaction pathway in which initial C-C bond formation takes place at C3 of indole, followed by ring closure to give the observed products. Insights gleaned from these calculations indicate that the solvent, either TFE or HFIP, can stabilize the transition state through H-bonding interactions with oxygen of the azaoxyallyl cation and other relevant intermediates, thereby increasing the rates of these reactions.
- DiPoto, Maria C.,Hughes, Russell P.,Wu, Jimmy
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supporting information
p. 14861 - 14864
(2015/12/08)
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- Iridium-catalyzed C-3 allylation of indoles with allylic alcohols promoted by a bronsted acid
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A highly regioselective method has been developed for the allylation of indoles with an iridium catalyst. This regioselective procedure uses allylic alcohols directly as allylating agents in the presence of a catalytic amount of sulfuric acid. A wide rang
- Chen, Shu-Jie,Lu, Guo-Ping,Cai, Chun
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supporting information
p. 1717 - 1724
(2014/07/08)
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- Hydrogen-bond-assisted activation of allylic alcohols for palladium-catalyzed coupling reactions
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We report direct activation of allylic alcohols using a hydrogen-bond-assisted palladium catalyst and use this for alkylation and amination reactions. The novel catalyst comprises a palladium complex based on a functionalized monodentate phosphoramidite ligand in combination with urea additives and affords linear alkylated and aminated allylic products selectively. Detailed kinetic analysis show that oxidative addition of the allyl alcohol is the rate-determining step, which is facilitated by hydrogen bonds between the alcohol, the ligand functional group, and the additional urea additive. Hydrogen Bond Rule(s): Direct activation of allylic alcohols and subsequent alkylation and amination reactions are reported. The new catalyst is based on functionalized palladium and phosphoramidite ligands to allow hydrogen bond-assisted activation. Kinetic data are in line with this mechanism as the oxidative addition is the rate-determining step.
- Gumrukcu, Yasemin,Debruin, Bas,Reek, Joost N. H.
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p. 890 - 896
(2014/03/21)
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- Direct oxidative coupling of N-acetyl indoles and phenols for the synthesis of benzofuroindolines related to phalarine
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Inspired by the biogenetic synthesis of benzofuro-indoline-containing natural products, we designed an oxidative coupling between phenol and N-acetyl indoles. This straightforward and direct radical process, mediated by 2,3-dichloro-5,6-dicyano-1,4-benzoquinone and FeCl 3 allowed the regioselective synthesis of benzofuro[3,2-b]indolines, whose structure is found in the natural product phalarine.
- Tomakinian, Terry,Guillot, Rgis,Kouklovsky, Cyrille,Vincent, Guillaume
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supporting information
p. 11881 - 11885
(2015/01/09)
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- Palladium-catalyzed decarboxylative allylation and benzylation of N-alloc and N-Cbz indoles
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A set of general methods for the palladium-catalyzed decarboxylative C3-allylation and C3-benzylation of indoles, starting from the corresponding N-alloc and N-Cbz indoles, respectively, is reported. This chemistry provides ready access to a wide range of
- Montgomery, Thomas D.,Zhu, Ye,Kagawa, Natsuko,Rawal, Viresh H.
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supporting information
p. 1140 - 1143
(2013/03/29)
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- Aryl Substituted Indoles and Their Use as Blockers of Sodium Channels
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The invention relates to aryl and heteroaryl substituted compounds of Formula (I), and pharmaceutically acceptable salts, prodrugs, or solvates thereof, wherein G, R1, and Z1-Z5 are defined as set forth in the specification. The invention is also directed to the use of compounds of Formula (I) to treat a disorder responsive to the blockade of sodium channels. Compounds of the present invention are especially useful for treating pain.
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Paragraph 0528
(2013/11/19)
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- Catalytic diastereo- and enantioselective annulations between transient nitrosoalkenes and indoles
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Caught in transition: An efficient catalytic system is the key to the successful development of the first highly diastereo- and enantioselective annulation reaction between indoles and transient nitrosoalkenes. This robust reaction affords structurally unique architectures with up to three new chiral centers. The products can be readily elaborated into other indoline-based chiral heterocyclic motifs, including those of pyrrolidinoindoline alkaloids. Copyright
- Zhang, Yu,Stephens, David,Hernandez, Graciela,Mendoza, Rosalinda,Larionov, Oleg V.
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supporting information
p. 16612 - 16615
(2013/03/14)
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- Stereospecific benzyne-induced olefination from β-amino alcohols and its application to the total synthesis of (-)-1-deoxy-D-fructose
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'Ole in one! Treatment of β-amino alcohols with CS2 under alkaline conditions gave 1,3-thiazolidine-2-thiones, which were then treated with benzyne generated in situ. The reaction underwent an unprecedented addition-elimination process to give the desired olefins in 60-87 yields (see scheme; DBU=1,8-diazabicyclo[5.4.0]undec-7-ene). Copyright
- Hwu, Jih Ru,Hsu, Yung Chang
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p. 4727 - 4731
(2011/06/09)
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- An efficient one-pot synthesis of 2-benzylpyrroles and 3-benzylindoles
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One-pot regioselective benzylation of pyrroles and indoles using zirconium tetrachloride is discussed. This has been achieved by in-situ generation of di(1H-pyrrol-1-yl)zirconium(IV) chloride and di(1H-indol-1-yl)zirconium(IV) chloride. It was observed th
- Sharma, Ratnesh,Chouhan, Mangilal,Sood, Divya,Nair, Vipin A.
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experimental part
p. 305 - 309
(2012/01/03)
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- Scope of the allylation reaction with [RuCp(PP)]+ catalysts: Changing the nucleophile or allylic alcohol
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The scope of the dehydrative allylation reaction using allyl alcohol as allyl donor with [RuCp(PP)]+ complexes as catalysts is explored. Aliphatic alcohols are successfully allylated with allyl alcohol or diallyl ether, obtaining high selectivity for the alkyl allyl ether. The reactivity of aliphatic alcohols is in the order of primary > secondary tertiary. The tertiary alcohol 1-adamantanol reacts extremely slowly in the absence of strong acid, but when HOTs is added, reasonable yields of 1-adamantyl allyl ether are obtained. The alkyl allyl ether is found to be the thermodynamically favored product over diallyl ether. Apart from alcohols, thiols and indole are also efficiently allylated, while aniline acts as a catalyst inhibitor. Allylation reactions with various substituted allylic alcohols give products with retention of the substitution pattern. It is proposed that a Ru(IV) σ-allyl species plays a key role in the mechanism of these allylation reactions.
- Van Rijn, Jimmy A.,Guijt, Marieke C.,De Vries, Dwight,Bouwman, Elisabeth,Drent, Eite
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experimental part
p. 212 - 219
(2012/04/17)
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- Ruthenium(IV) complexes featuring p,O-chelating ligands: Regioselective substitution directly from allylic alcohols
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(Figure Presented) Branching out: A new ruthenium(IV) complex (1), containing a P,O-chelating ligand, is an efficient precatalyst for regioselective allylations starting from various allylic alcohol derivatives.
- Sundararaju, Basker,Achard, Mathieu,Demerseman, Bernard,Toupet, Loic,Sharma, Gangavaram V. M.,Bruneau, Christian
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supporting information; experimental part
p. 2782 - 2785
(2010/07/06)
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- Alkylation of the ambident indole ion in ionic liquids
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Alkylation of the ambident indole anion in ionic liquids has been investigated. The reaction rate is greater in ionic liquids than in organic solvents. The polarity of certain ionic liquids has been determined to be located between methanol and acetonitrile. 2008 Springer Science+Business Media, Inc.
- Vavilina,Zicmanis,Drozdova,Mekss,Klavins
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p. 530 - 541
(2013/07/27)
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- Allylation of N-Heterocycles with allylic alcohols employing self-assembling palladium phosphane catalysts
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The first palladium catalyst system that allows the direct allylation of indoles with allylic alcohols as substrates with water being the only byproduct is presented. The application of self-assembing ligands based on complementary hydrogen bonding was the key to success.
- Usui, Ippei,Schmidt, Stefan,Keller, Manfred,Breit, Bernhard
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supporting information; body text
p. 1207 - 1210
(2009/04/06)
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- Fast, efficient Ru(IV)-catalysed regioselective allylation of indoles using allyl alcohol (without additives) under mild conditions
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The new Ru(iv) salt, [Ru(η3-C3H 5)(Cp*)(CH3CN)2](PF6) 2, is an excellent catalyst for the regioselective allylation of a variety of indole compounds using allyl alcohol as substrate; there are no co-catalysts required in this chemistry and the yields and reaction conditions are very favorable. The Royal Society of Chemistry.
- Zaitsev, Alexey B.,Gruber, Stefan,Pregosin, Paul S.
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p. 4692 - 4693
(2008/10/09)
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- One-pot synthesis of polysubstituted indoles from aliphatic nitro compounds under mild conditions
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Polysubstituted indoles can be prepared directly from functionalized nitroalkanes under very mildly acidic conditions in a simple, one-pot, two-stage procedure.
- Simoneau, Christopher A.,Strohl, Alexis M.,Ganem, Bruce
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p. 1809 - 1811
(2008/02/05)
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- Novel gallium-mediated C3-allylation of indoles and pyrroles in aqueous media promoted by Bu4NBr
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A mild and efficient protocol for the coupling of indoles and pyrroles with allyl halides such as allyl bromide, crotyl bromide and propargyl bromide in the presence of gallium metal in a Bu4NBr-DMF-H2O system has been developed. The reaction is equally effective when cadmium is used in lieu of gallium and the corresponding 3-allyl indoles and 3-allyl pyrroles were obtained in almost comparable yields.
- Prajapati, Dipak,Gohain, Mukut,Gogoi, Baikuntha J.
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p. 3535 - 3539
(2007/10/03)
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- Concise synthesis and transannular inverse electron demand Diels-Alder reaction of [3](3,6)pyridazino[3](1,3)indolophane. Rapid access to a pentacyclic indoloid system.
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[reaction: see text] The title compound was synthesized concisely from indole. A 2-fold sequential hydroboration/Suzuki-Miyaura cross-coupling was employed to generate the cyclophane. When heated in N,N-diethylaniline, it underwent a transannular inverse electron demand Diels-Alder (IEDDA) reaction to form a pentacyclic product, which appears to be well suited as a precursor to a variety of indole alkaloids such as strychnine.
- Bodwell, Graham J,Li, Jiang
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p. 127 - 130
(2007/10/03)
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- Regioselectivity Control in Alkylation Reactions of Indolyl Ambident Anion
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The regioselectivity of N- and C-3(β)-alkylations of indolylmetal salts was studied under various conditions.The effect of counter metal ion is crucial in determining the regioselectivity.In tetrahydrofuran, exclusive N-alkylation occurred with the potassium salt, but the extent of C-3-alkylation increased with the sodium and lithium salts and became predominant with the magnesium bromide salt.However, N-alkylation was favoured generally in more polar solvents and for alkyl toluene-p-sulphonates it was favoured even with magnesium bromide salts.The reactivity and regioselectivity of the alkylations were correlated with the calculated electron density of the indolyl anion and with 13C n.m.r. chemical shifts of the metal salts.
- Nunomoto, Sadaaki,Kawakami, Yuhsuke,Yamashita, Yuya,Takeuchi, Hisato,Eguchi, Shoji
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p. 111 - 114
(2007/10/02)
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- A NEW CARBON-CARBON BOND FORMING REACTION IN INDOLE CHEMISTRY. C3-ARYLATION AND ALKYLATION WITH PHENYL (β-INDOLYL)IODONIUM TRIFLUOROACETATE
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Phenyl(β-indolyl)iodonium trifuoroacetate was reacted with various alkyl and aryllithiums (CH3, n-C4H9, C3H5, C6H5) in BF3Et2O/THF to yield C3-alkylation and arylation of the indole nucleus with reductive elimination of iodobenzene.
- Moriarty, Robert M.,Ku, Y. Y.,Sultana, M.,Tuncay, Atilla
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p. 3071 - 3074
(2007/10/02)
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- Synthesis of Prenylated Indoles
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Interaction of magnesium indolates and allyl oxides in the presence of bis(triphenylphosphine)nickel dichloride results in indole β-allylation, except in cases involving highly substituted indoles and allyl alcohols.This method permits the β-prenylation of indole and α-prenylation of ketones (by way of their magnesium enaminates).Base-induced interaction of ethynyldimethylcarbinyl chloride and indole under a variety of conditions yields β-(β,β-dimethylvinyl)quinoline as well as variously dehydroprenylated indoles. α-Lithiation of N-(benzenesulfonyl)indole followed by treatmentwith prenyl bromide or β,β-dimethylacrylyl chloride produces α-prenyl- or α-oxoprenylidole derivatives, the sodium amalgam reduction of the former of which yields α-prenylidole.Interaction of β-cuprated N-(benzenesulfonyl)indole with the same halides followed by reduction affords β-prenylindole and β-oxoprenylindole, the latter also being the product of the reaction of magnesium indolate and the acid chloride.Lithium aluminum hydride reduction of 1-(benzenesulfonyl)-3-oxoprenylindole affords an alcohol, whose base hydrolysis produces β-dehydroprenylindole, a compound whose dimerization has led previously to naturally occuring yuehchukene.
- Wenkert, Ernest,Angell, E. Charles,Ferreira, Vitor F.,Michelotti, Enrique L.,Piettre, Serge R.,et al.
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p. 2343 - 2351
(2007/10/02)
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- INDOLE SYNTHESES UTILIZING o-METHYLPHENYL ISOCYANIDES.
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New indole synthesis starting with o-methylphenyl isocyanides such as o-tolyl, 2,4-xylyl, and 2,6-xylyl isocyanide is described. Treatment of o-tolyl isocyanide with LDA in diglyme at minus 78 degree C generated selectively o-(lithiomethyl)phenyl isocyanide in an almost quantitative yield, which on warming up to room temperature was cyclized to indole after aqueous workup. Similarly, 2,4-xylyl and 2,6-xylyl and 2,6-xylyl isocyanides were cyclized to 5-methylindole and 7-methylindole quantitatively. The o-(lithiomethyl)phenyl isocyanides reacted with electrophiles such as alkyl halides and alkylene oxides to give o-alkylphenyl isocyanides, which were cyclized via the lithiation at the orthobenzylic carbon to afford 3-substituted indoles.
- Ito,Kobayashi,Seko,Saegusa
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- REACTIVITY OF UNSATURATED INDOLE DERIVATIVES TOWARDS ORGANOMETALLIC AND RADICAL POLYMERIZATION INITIATORS
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The ability of 3-allylindole (3-AIN) and 3-indolyl vinyl ketone (3-INVK) (prepared by literature methods) to polymerise has been investigated.After addition of pure 3-AIN to AlBu3i/TiCl3ARA catalyst, with molar ratios Al/Ti=3 and monomer/Ti=20, 3-AIN is recovered unchanged; on the contrary, if the monomer is previously complexed with an equimolar amount of either AlBu3i or TiCl3, the 3-(1-propyl)indole or a dimer are isolated, respectively.In every run no polymer formation was observed.In order to get information about interactions of the bimetallic Ziegler-Natta system with the indole nucleus, polymerisation of 4-methyl-1-pentene in the presence of the AlBu3i/TiCl3/indole system, using different values of indole/TiCl3 and indole/AlBu3i ratios, has also been carried out.Attempts to polymerise 3-INVK have been performed both by an anionic catalyst, such as ZnBu2i in tetrahydrofuran, and by a radical initiator, such as azobisisobutyronitrile in 2-propanol.In both cases no polymer was isolated, but when catalytic amounts of the initiators are employed, the monomer is recovered unchanged.When equimolar amounts of monomer to catalyst are used, 3-indolyl 4-methyl-1-pentyl ketone and 3-cyano-3-methyl-1-butyl 3-indolyl ketone are obtained in the anionic and radical polymerisation, respectively.Some hypotheses are put forward to explain the peculiar behaviour of vinyl monomers containing the indole nucleus.
- Pini, Dario
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p. 473 - 478
(2007/10/02)
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- Phase-Transfer Alkylation of Heterocycles in the Presence of 18-Crown-6 and Potassium tert-Butoxide
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It has been found that the N-alkylation of heterocyclic compounds bearing an acidic hydrogen atom attached to nitrogen can be accomplished in diethyl ether via a phase-transfer process in which 18-crown-6 is employed as the catalyst and potassium tert-butoxide is employed as the base.In this manner, pyrrole (1), indole (2), pyrazole (3), imidazole (4), benzimidazole (5), benzotriazole (6), carbazole (7), and methyl indole-3-acetate (8) can be successfully alkylated.The procedure is convenient and mild and generally gives rise to exclusive N-alkylation.
- Guida, Wayne C.,Mathre, David J.
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p. 3172 - 3176
(2007/10/02)
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