- tBuOK-Promoted Cyclization of Imines with Aryl Halides
-
A transition-metal-free indole synthesis using radical coupling of 2-halotoluenes and imines via the later-stage C-N bond construction was reported for the first time. It includes an aminyl radical generation by C-H cleaving addition of 2-halotoluenes to imines via the carbanion radical relay and an intramolecular coupling of aryl halides with aminyl radicals. One standard condition can be used for all halides including F, Cl, Br, and I. No extra oxidant or transition metal is required.
- Li, Ya-Wei,Zheng, Hong-Xing,Yang, Bo,Shan, Xiang-Huan,Qu, Jian-Ping,Kang, Yan-Biao
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p. 4553 - 4556
(2020/06/08)
-
- Scope, Kinetics, and Mechanism of “On Water” Cu Catalysis in the C–N Cross-Coupling Reactions of Indole Derivatives
-
A simple and cost-effective protocol for the C–N cross coupling of indole derivatives with aryl iodides using CuI/phenanthroline catalytic system in aqueous and DME/H2O solvent mixture is described. The reactions were performed in the absence of phase-transfer catalyst, and afforded N-arylated products in moderate to excellent yields under mild reaction conditions. A systematic tuning of reaction conditions using DME as a co-solvent enables to improve product yields of N-arylation reactions. The broad substrate scope, easy performance, and low loading of catalyst as well as ligand render this approach appropriate for large scale processes. The mechanism of “on water” Cu-catalyzed N-arylation reaction is investigated using kinetic and computational studies, which reveal interesting mechanistic aspects of the reaction. A series of kinetic experiments showed significant rate enhancement for “on water” Cu-catalyzed N-arylation over the reaction performed in the organic solvent (DME). Computational studies corroborated “on water” rate acceleration by delineating the role of water in the reaction. The water induces rate acceleration by stabilizing the transition state of oxidative addition through hydrogen bonding interactions, presumably at the oil-water interface, and thus helps to reduce the free energy of activation of oxidative addition of iodobenzene to the Cu complex, which is identified as the rate-limiting step of reaction.
- Malavade, Vrunda,Patil, Manish,Patil, Mahendra
-
supporting information
p. 561 - 569
(2020/02/05)
-
- Palladium-Catalyzed C-N Cross-Coupling of NH-Heteroarenes and Quaternary Ammonium Salts via C-N Bond Cleavage
-
In this paper, we extend the substrate class of Buchwald-Hartwig amination to quaternary ammonium salts. In the presence of Pd(OAc)2 and t-BuXPhos, the coupling of aryl- or arylmethyltrimethylammonium triflates with NH-heteroarenes via C-N bond cleavage affords the desired N-aryl or N-arylmethyl heteroarenes in moderate to excellent yields.
- Chen, Hongyi,Yang, Hongqin,Li, Nutao,Xue, Xinghua,He, Ze,Zeng, Qingle
-
p. 1679 - 1685
(2019/08/20)
-
- Transition-Metal-Free Synthesis of 1,2-Disubstituted Indoles
-
Herein, we report a new transition-metal-free robust and cost-effective method for synthesis of 1,2-disubstituted indoles from easily available unactivated (i.e. without EWG, PPh3 or SiR3 groups) tertiary amides. Scope of synthetic applicability of the presented protocol was shown on 23 examples of 1,2-disubstituted indoles with different substitution patterns obtained in good to excellent yields. The reported method turned out to be especially effective for synthesis of N-arylated 2-CF3-indoles. Moreover, this approach can be performed in a one-pot two-step manner directly from commercially available secondary amines. Mechanistic studies showed that acyl transfer might be an important step in the course of the reaction. Viability of the presented approach for benzofurans and benzothiophenes synthesis was also discussed.
- Chesnokov, Gleb A.,Ageshina, Alexandra A.,Topchiy, Maxim A.,Nechaev, Mikhail S.,Asachenko, Andrey F.
-
p. 4844 - 4854
(2019/08/01)
-
- Fabrication of an amyloid fibril-palladium nanocomposite: A sustainable catalyst for C-H activation and the electrooxidation of ethanol
-
Amyloids are highly ordered nanofibrils and their tensile strength is similar to that of steel, which makes them resistant to extreme pH and temperature. Based on this rationale, we demonstrate a facile synthesis of palladium, copper, platinum, gold and silver nanocomposites using α-Synuclein (α-Syn) fibrils as a template. We showed that an α-Syn-fibril-palladium nanoparticles (α-Syn-PdNPs) composite can be used as a heterogeneous catalyst in C-H bond activation and the electrooxidation of ethanol. The study demonstrated α-Syn-PdNPs to be a superior heterogeneous catalyst for the synthesis of pharmaceutically valuable benzofuran, naphthofuran, coumarin and N-arylindole via C-H activation. Further, the electrooxidation of ethanol using α-Syn-PdNPs displayed an electrochemically active surface area of 160.6 m2 g-1, which is much higher than the previously reported values for supported Pd nanocomposites.
- Jayarajan, Ramasamy,Kumar, Rakesh,Gupta, Jagriti,Dev, Gayathri,Kadu, Pradeep,Chatterjee, Debdeep,Bahadur, Dhirendra,Maiti, Debabrata,Maji, Samir K.
-
supporting information
p. 4486 - 4493
(2019/03/06)
-
- ORGANIC COMPOUND FOR OPTOELECTRONIC DEVICE AND ORGANIC OPTOELECTRONIC DEVICE AND DISPLAY DEVICE
-
The present invention relates to an organic compound for an organic optoelectronic device represented by chemical formula 1, and an organic optoelectronic device and a display device using the same. The details of the chemical formula 1 are as defined in the specification. One embodiment of the present invention provides a compound for an organic optoelectronic device capable of realizing an organic optoelectronic device with high-efficiency and long-life. Another embodiment of the present invention provides an organic optoelectronic device including the compound for the organic optoelectronic device.
- -
-
Paragraph 0167-0170
(2019/10/22)
-
- CNT-CuO catalyzed C–N bond formation for N-arylation of 2-phenylindoles
-
Carbon nanotube–copper oxide (CNT–CuO) nanocomposites were prepared by depositing CuO nanoparticles onto functionalized CNT surfaces. The structure and elemental content of CNT–CuO were characterized using transmission electron microscopy, X-ray diffraction, and Auger electron spectroscopy. The prepared CNT-CuO was subsequently employed as a catalyst for the coupling reaction of 2-phenylindole with aryl iodides to provide the desired N-aryl 2-phenylindoles in good yields.
- Lim, Jeongah,Kim, Ji Dang,Choi, Hyun Chul,Lee, Sunwoo
-
supporting information
(2019/10/14)
-
- Borane-catalyzed indole synthesis through intramolecular hydroamination
-
The reaction of 2-alkynyl anilines with catalytic amounts of B(C6F5)3 (5 mol%) resulted in the formation of 2-substituted indoles according to an intramolecular hydroamination in good to excellent yields. Reaction intermediates as well as products were characterized by NMR spectroscopy and by X-ray crystallography. The domino hydroamination/hydrogenation sequence allowed the efficient synthesis of tetrahydroquinoline 8 in good yield.
- Tussing, Sebastian,Ohland, Miriam,Wicker, Garrit,Fl?rke, Ulrich,Paradies, Jan
-
p. 1539 - 1545
(2017/02/10)
-
- Molecular-Iodine-Catalyzed Cyclization of 2-Alkynylanilines via Iodocyclization-Protodeiodination Sequence
-
Molecular iodine catalyzes a cyclization of N-aryl-2-alkynylanilines, which proceeds through the iodocyclization of 2-alkynylanilines followed by the protodeiodination of the iodocyclized intermediates at room temperature. Furthermore, the molecular iodine catalysis can be applied to the cascade cyclization of 2-(enynyl)aniline and to the tandem cyclization-addition reaction of 2-alkynylanilines with α,β-enones.
- Takeda, Yuichiro,Kajihara, Ryota,Kobayashi, Naoko,Noguchi, Keiichi,Saito, Akio
-
supporting information
p. 6744 - 6747
(2017/12/26)
-
- Catalytic Access to Indole-Fused Benzosiloles by 2-Fold Electrophilic C-H Silylation with Dihydrosilanes
-
A protocol for the catalytic synthesis of indole-fused benzosiloles starting from 2-aryl-substituted indoles and dihydrosilanes is reported. Compared to known procedures, this method does not require prefunctionalized starting materials and, hence, allows for a rapid access to those siloles. The net reaction is a 2-fold electrophilic C-H silylation catalyzed by cationic Ru-S complexes. Both reaction steps were separately investigated, and these results eventually led to the development of a two-step procedure. By preparing new Ru-S complexes with different weakly coordinating anions (WCAs), it is also shown that the latter can have a dramatic influence on the outcome of these reactions. Furthermore, the substrate scope of the new method is discussed.
- Omann, Lukas,Oestreich, Martin
-
supporting information
p. 767 - 776
(2017/04/21)
-
- Isocyanide-Induced Activation of Copper Sulfate: Direct Access to Functionalized Heteroarene Sulfonic Esters
-
A novel and direct approach to alkyl/aryl heteroarene sulfonic esters using copper sulfate as the environmentally benign inorganic sulfonation reagent was first realized with the aid of isocyanide. A variety of heterocycles reacted to afford the corresponding sulfonic esters through C?H functionalization. In this transformation, the otherwise inert copper sulfate was unusually activated by an isocyanide and employed as the source of the sulfonic substituents in an unprecedented fashion. The findings suggest that an appropriate activator may liberate the chemical activities of some relatively inert inorganic salts for organic synthesis.
- Hong, Xiaohu,Tan, Qitao,Liu, Bingxin,Xu, Bin
-
supporting information
p. 3961 - 3965
(2017/03/27)
-
- Selective arylation/annulation cascade reactions of 2-alkynylanilines with diaryliodonium salts
-
An efficient Cu catalyzed selective arylation/annulation cascade reaction of 2-alkynylanilines with diaryliodonium salts was developed. This reaction was selective to N-arylation instead of C-arylation, which provides a simple synthetic method for N-aryl indoles.
- Duan, Ying,Yang, Yanliang,Dai, Xiaoyu,Li, Dongmi
-
p. 1837 - 1840
(2016/12/07)
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- Access to Indole Derivatives from Diaryliodonium Salts and 2-Alkynylanilines
-
An efficient, environmentally friendly, and operationally simple procedure to 1,2-disubstituted indoles from 2-alkynylanilines and diaryliodonium salts has been developed. This reaction proceeds smoothly under metal-free conditions. The products obtained could be transferred into 3,3′-diindolylmethane with DMSO catalyzed by palladium. The isotopic label experiments indicated that the methylene group in 3,3′-diindolylmethane is derived from DMSO. The diverse indoles were obtained in up to 90% yield for 28 examples.
- Li, Pengfei,Weng, Yunxiang,Xu, Xianxiang,Cui, Xiuling
-
p. 3994 - 4001
(2016/06/09)
-
- Synthesis of 1,2-Disubstituted Indoles from α-Aminonitriles and 2-Halobenzyl Halides
-
The α-alkylation of deprotonated Strecker products derived from primary amines and aromatic aldehydes with 2-halobenzyl halides furnishes intermediates that can be cyclized to 1,2-disubstituted indoles in moderate to high yields (up to 94% over two steps) by microwave-assisted copper- or palladium-catalyzed intramolecular cross-coupling.
- Bachon, Anne-Katrin,Opatz, Till
-
p. 1858 - 1869
(2016/03/15)
-
- Utilizing Mor-DalPhos/palladium-catalyzed monoarylation in the multicomponent one-pot synthesis of indoles
-
The application of a Mor-DalPhos/palladium catalyst system in the one-pot, multicomponent assembly of substituted indoles from ortho-chlorohaloarenes, alkyl ketones (including acetone), and primary amines is reported. The described protocols offer improved substrate scope in all three reaction components, under more mild conditions and without the need for an additional drying agent. Also reported are the first examples of such multicomponent reactions where all reactants are combined at the start of the reaction, without the need for inert atmosphere reaction conditions.
- Rotta-Loria, Nicolas L.,Borzenko, Andrey,Alsabeh, Pamela G.,Lavery, Christopher B.,Stradiotto, Mark
-
p. 100 - 106
(2015/01/30)
-
- Copper-catalyzed N-arylation of 2-arylindoles with aryl halides
-
10 mol% CuI combined with the DMEDA ligand can efficiently catalyze the N-arylation of 2-arylindoles with aryl iodides and aryl bromides in good to excellent yields. The aryl halides bearing electron-rich or electron-deficient functional groups can be wel
- Liu, Wei,Han, Li-Ya,Liu, Rui-Li,Xu, Li-Ge,Bi, Yan-Lan
-
p. 1240 - 1243
(2014/11/07)
-
- Palladium-catalyzed annulation of diarylamines with olefins through C-H activation: Direct access to N-arylindoles
-
A palladium-catalyzed dehydrogenative coupling between diarylamines and olefins has been discovered for the synthesis of substituted indoles. This intermolecular annulation approach incorporates readily available olefins for the first time and obviates the need of any additional directing group. An ortho palladation, olefin coordination, and β-migratory insertion sequence has been proposed for the generation of olefinated intermediate, which is found to produce the expected indole moiety.
- Sharma, Upendra,Kancherla, Rajesh,Naveen, Togati,Agasti, Soumitra,Maiti, Debabrata
-
supporting information
p. 11895 - 11899
(2015/01/09)
-
- One-pot approach to 1,2-disubstituted indoles via Cu(II)-catalyzed coupling/cyclization under aerobic conditions and its application for the synthesis of polycyclic indoles
-
A straightforward assembly of 1,2-disubstituted indoles has been developed through a Cu(II)-catalyzed domino coupling/cyclization process. Under aerobic conditions, a wide range of 1,2-disubstituted indole derivatives were efficiently and facilely synthesized from 2-alkynylanilines and boronic acids. 2-(2-Bromoaryl)-1-aryl-1H-indoles, which were selectively generated in one pot under the Cu catalysis, afforded the indolo[1,2-f]phenanthridines via Pd-catalyzed intramolecular direct C(sp2)-H arylation. The one-pot tandem approaches to the polycyclic indole derivatives were also successfully achieved.
- Gao, Jilong,Shao, Yingying,Zhu, Jiaoyan,Zhu, Jiaqi,Mao, Hui,Wang, Xiaoxia,Lv, Xin
-
p. 9000 - 9008
(2014/12/11)
-
- Exploration of C-H and N-H-bond functionalization towards 1-(1,2-diarylindol-3-yl)tetrahydroisoquinolines
-
The synthesis of 1,2,3-trisubstituted indoles was investigated. More specifically, straightforward synthetic routes towards 1-(1,2-diarylindol-3-yl)-N-PG-THIQs (PG = protecting group, THIQ = tetrahydroisoquinoline) employing transition metal-catalyzed C-H and N-H-bond functionalization were explored. It was found that the synthesis of the target compounds is strongly dependent on the order of events. Hence, depending on the requirements of a synthetic problem the most suitable and promising pathway can be chosen. Additionally, a new synthetic approach towards 1,2-diarylindoles starting from 1-arylindole could be established in the course of our investigation by using a palladium-catalyzed protocol. Such 1,2-diarylindoles were successfully reacted with N-Boc-THIQ to furnish 1,2,3-trisubstituted indoles as target compounds. Furthermore, regioselective N-arylation of protected and unprotected 1-(indol-3-yl)-THIQs was successfully conducted using either simple iron or copper salts as catalysts.
- Ghobrial, Michael,Mihovilovic, Marko D.,Schnürch, Michael
-
supporting information
p. 2186 - 2199
(2014/12/11)
-
- SILANYLOXYARYL PHOSPHINE LIGAND AND USES THEREOF IN C-N CROSS-COUPLING
-
The present invention pertains to silanyloxyaryl phosphine ligands of formula (I) and their uses with transition metal catalyst precursors for organic synthesis reactions. More particularly, the present invention pertains to the use of silanyloxyaryl phosphine ligands and with transition metal catalyst precursors in C-N cross-coupling reactions.
- -
-
Paragraph 00107-00111; 00124; 00125
(2013/11/18)
-
- BippyPhos: A single ligand with unprecedented scope in the Buchwald-Hartwig amination of (hetero)aryl chlorides
-
Over the past two decades, considerable attention has been given to the development of new ligands for the palladium-catalyzed arylation of amines and related NH-containing substrates (i.e., Buchwald-Hartwig amination). The generation of structurally diverse ligands, by research groups in both academia and industry, has facilitated the accommodation of sterically and electronically divergent substrates including ammonia, hydrazine, amines, amides, and NH heterocycles. Despite these achievements, problems with catalyst generality persist and access to multiple ligands is necessary to accommodate all of these NH-containing substrates. In our quest to address this significant limitation we identified the BippyPhos/[Pd(cinnamyl)Cl]2 catalyst system as being capable of catalyzing the amination of a variety of functionalized (hetero)aryl chlorides, as well as bromides and tosylates, at moderate to low catalyst loadings. The successful transformations described herein include primary and secondary amines, NH heterocycles, amides, ammonia and hydrazine, thus demonstrating the largest scope in the NH-containing coupling partner reported for a single Pd/ligand catalyst system. We also established BippyPhos/ [Pd(cinnamyl)Cl]2 as exhibiting the broadest demonstrated substrate scope for metal-catalyzed cross-coupling of (hetero)aryl chlorides with NH indoles. Furthermore, the remarkable ability of BippyPhos/[Pd(cinnamyl)Cl] 2 to catalyze both the selective monoarylation of ammonia and the N-arylation of indoles was exploited in the development of a new one-pot, two-step synthesis of N-aryl heterocycles from ammonia, ortho- alkynylhalo(hetero)arenes and (hetero) aryl halides through tandem N-arylation/hydroamination reactions. Although the scope in the NH-containing coupling partner is broad, BippyPhos/[Pd(cinnamyl)Cl]2 also displays a marked selectivity profile that was exploited in the chemoselective monoarylation of substrates featuring two chemically distinct NH-containing moieties.
- Crawford, Sarah M.,Lavery, Christopher B.,Stradiotto, Mark
-
supporting information
p. 16760 - 16771
(2014/01/06)
-
- Alternative reaction pathways in domino reactions of hydrazinediidozirconium complexes with alkynes
-
Reaction of [Zr{(NAr)2Npy}(NMe2) 2] (Ar=3,5-xylyl: 2 a, mesityl: 2 b) with one or two molar equivalents of 1,1-diphenylhydrazine gave the mixed amido/hydrazido(1-) complex [Zr{(NMes)2Npy}(HNNPh2)(NMe2)] (3), the bis-hydrazido complex [Zr{(NMes)2Npy}(HNNPh 2)2] (4), and, in the presence of excess 4-dimethylaminopyridine (DMAP), hexacoordinate hydrazinediidozirconium complexes [Zr{(NXyl)2Npy}(=NN(Me)Ph)(dmap)2] (5) and [Zr{(NXyl)2Npy}(=NNPh2)(dmap)2] (6). The reaction of one equivalent of the zirconium-hydrazinediide [Zr{(NTBS) 2Npy}(NNPh2)(py)] (1) with disubstituted alkynes at RT for 16 h led to the formation of seven-membered diazazirconacycles 7 a-7 e in high yields. Similar reactivity was observed by reacting bis-amido complex 2 b with one molar equivalent of the corresponding alkyne and diphenylhydrazine. The formation of the seven-membered zirconacycles implied a key coupling step that involved the alkyne and one of the aryl rings of the diphenylhydrazinediido ligand. In some cases, such as the reaction with 2-butyne, the corresponding metallacycle was only obtained in modest yields (45 % for the reaction with 2-butyne) and a second major product, vinylimido complex 9, was formed in almost equal amounts (42 %) by 1,2-amination (formal insertion of the alkyne). The formation of compounds 7 a and 9 followed in part the same sequence of reaction steps and a key intermediate, an azirinido complex, represented a "bifurcation point" in the reaction network. Reaction of 1.2 equivalents of several diarylhydrazines and various substituted alkynes (1 equiv) at ambient temperature (or at 80 °C) in the presence of 10 mol % [Zr{(NXyl)2Npy}(NMe2)2] (2 a) gave the corresponding indole derivatives. On the other hand, the replacement of 1,1-diarylhydrazines by 1-methyl-1-phenyl hydrazine led to head-to-head cis-1,3-enynes in good yields. A fork in the road: Azirinidozirconium species A is the key intermediate for two reaction pathways in the metal-catalyzed coupling of diarylhydrazines and alkynes. Electrophilic metal-azirinide attack at the ortho C atom (C) affords substituted indoles. Copyright
- Gehrmann, Thorsten,Scholl, Solveig A.,Fillol, Julio Lloret,Wadepohl, Hubert,Gade, Lutz H.
-
supporting information; experimental part
p. 3925 - 3941
(2012/05/20)
-
- Efficient palladium-catalyzed synthesis of substituted indoles employing a new (silanyloxyphenyl)phosphine ligand
-
The new and easily prepared OTips-DalPhos ligand (L1) offers broad substrate scope at relatively low loadings in the palladium-catalyzed C-N cross-coupling/cyclization of o-alkynylhalo(hetero)arenes with primary amines, affording indoles and related heterocyclic derivatives in high yield.
- Lavery, Christopher B.,McDonald, Robert,Stradiotto, Mark
-
supporting information; experimental part
p. 7277 - 7279
(2012/07/28)
-
- Nickel-catalyzed, base-mediated amination/hydroamination reaction sequence for a modular synthesis of indoles
-
A catalytic system consisting of [Ni(cod)2] and ligand dppf enabled an efficient synthesis of differently substituted indoles through a modular reaction sequence, which consists of intermolecular aminations and intramolecular hydroaminations with ortho-alkynylhaloarenes.
- Ackermann, Lutz,Song, Weifeng,Sandmann, René
-
experimental part
p. 195 - 201
(2011/02/16)
-
- Pd(OAc)2-catalyzed regioselective arylation of indoles with arylsiloxane in acidic medium
-
(Figure Presented) Mild conditions have been developed to achieve a Pd(OAc)2-catalyzed cross-coupling between indoles and arylsiloxanes in the presence of TBAF and Ag2O in acidic medium. Electron-deficient arylsiloxanes presented high efficiency in this system to give the arylated indoles in excellent yields.
- Liang, Zunjun,Yao, Bangben,Zhang, Yuhong
-
supporting information; scheme or table
p. 3185 - 3187
(2010/08/20)
-
- On-water, microwave-assisted, Pd-catalyzed synthesis of indoles from imines and o-difunctionalized arenes
-
Regioselectively substituted indoles are prepared by a Pd-catalyzed C-C/C-N bond-forming sequence from imines and o-dihaloarenes or o-haloarene sulfonates. The heterogeneous reaction as a suspension in water and under microwave heating offers important advantages in comparison with the conventional reaction in an organic solvent, among them, operational simplicity, the employment of KOH solutions instead of alkoxides, and a dramatic reduction of reaction times.
- Barluenga, José,Jiménez-Aquino, Agustín,Aznar, Fernando,Valdés, Carlos
-
supporting information; experimental part
p. 11707 - 11711
(2010/11/04)
-
- Modular synthesis of indoles from imines and o-dihaloarenes or o-chlorosulfonates by a Pd-catalyzed cascade process
-
A detailed study of the scope of a new Pd-catalyzed synthesis of indolesfrom 1,2-dihaloarenes and o-halobenzene sulfonates and imines is descri bed. The cascade reaction comprises an imine a-arylation ollowed by an intramolecular C-N bond-forming reaction promoted by the same Pd catalyst. The reaction with 1,2-dibromobenzene shows wide scope and allows the introduction of aryl, alkyl, and vinyl substituents at different positions of the five-membered ring of the indole. The regioselective synthesis of indoles substituted in the six-membered ring can be carried out by employing o-dihalobenzene derivatives with two different halogens, taking advantage of the different reactivities of I, Br, and Cl in oxidative addition reactions. This paper also introduces a method for the efficient cleavage of the N-t-butyl group, thus allowing for the preparation of N-H indoles through the same methodology. Finally, the reaction with o-halosulfonates has been studied. The best substrates are o-chlorononaflates, which lead to indoles in very high yield. The reaction is particularlyappropriate for the synthesis of the challenging 6-substituted indoles. In view of the availability of o-chlorophenols, which are direct precur sors of the chlorononaflates, this reaction represents an efficient entry into indoles substituted in the six-membered ring. The concept is illustrated by the preparation of a 4,6-disubstituted indole from naturally occurring anethole.
- Barluenga, Jose,Jimenez-Aquino, Agustin,Aznar, Fernando,Valdes, Carlos
-
supporting information; experimental part
p. 4031 - 4041
(2009/09/04)
-
- A highly selective tandem cross-coupling of gem-dihaloolefins for a modular, efficient synthesis of highly functionalized indoles
-
(Chemical Equation Presented) A highly efficient method of indole synthesis using gem-dihalovinylaniline substrates and an organoboron reagent was developed via a Pd-catalyzed tandem intramolecular amination and an intermolecular Suzuki coupling. Aryl, alkenyl, and alkyl boron reagents are all successfully employed, making for a versatile modular approach. The reaction tolerates a variety of substitution patterns on the aniline leading to indoles with group at C2-C7. The orthogonal approach of the sequential copper- and palladium-mediated synthesis of 1,2-diarylindoles exploited the wide availability of diverse organoboron reagents.
- Fang, Yuan-Qing,Lautens, Mark
-
p. 538 - 549
(2008/09/17)
-
- Heterobimetallic cobalt/rhodium nanoparticle-catalyzed carbonylative cycloaddition of 2-alkynylanilines to oxindoles
-
(Chemical Equation Presented) The cobalt-rhodium heterobimetallic nanoparticle-catalyzed synthesis of oxindoles from 2-alkynylanilines in the presence of carbon monoxide is described.
- Park, Ji Hoon,Kim, Eunha,Chung, Young Keun
-
supporting information; experimental part
p. 4718 - 4721
(2009/05/31)
-
- The azaallylic anion as a synthon for Pd-catalyzed synthesis of heterocycles: domino two- and three-component synthesis of indoles
-
(Chemical Equation Presented) Piecing it all together with palladium: Two- and three-component cascade processes that are promoted by a multifunctional Pd catalyst lead to indoles in a highly efficient manner (see scheme). The key step is the Pd-catalyzed α-arylation of imines with o-dihalobenzene derivatives.
- Barluenga, Jose,Jimenez-Aquino, Agustin,Valdes, Carlos,Aznar, Fernando
-
p. 1529 - 1532
(2008/04/05)
-
- Efficient synthesis of 2-substituted indoles based on palladium(II) acetate/tri-tert-butylphosphine-catalyzed alkynylation/amination of 1,2-dihalobenzenes
-
A simple, efficient palladium(II) acetate/tri-tert-butylphosphine-catalyzed indole synthesis from o-alkynylhalobenzenes, readily available from 1,2-dihalobenzenes, has been achieved in good to excellent yields. A one-pot, Pd(OAc)2/t-Bu3P-catalyzed sequential reaction from 1-chloro-2-iodobenzene, phenylacetylene and amines has also been achieved in good yields.
- Tang, Zhen-Yu,Hu, Qiao-Sheng
-
p. 846 - 850
(2007/10/03)
-
- Catalytic C-H arylation of SEM-protected azoles with palladium complexes of NHCs and phosphines
-
The synthesis and catalytic evaluation of palladium complexes containing imidazolyl carbene ligand of varying steric and electronic properties is reported. These complexes catalyze the efficient C-H arylation of SEM-protected azole heteroarenes and thus provide a good method for preparation of a wide range of arylated free (NH)-azoles including pyrroles, indoles, imidazoles, and imidazo[1,2-a]pyridines. The reaction is operationally simple; the complexes are insensitive to moisture.
- Toure, B. Barry,Lane, Benjamin S.,Sames, Dalibor
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p. 1979 - 1982
(2007/10/03)
-
- 2-SUBSTITUTED INDOLES, THEIR PRECURSORS AND NOVEL PROCESSES FOR THE PREPARATION THEREOF
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Disclosed are processes for the preparation of 2-substituted indole compounds wherein the 2-substituent comprises an R4 group, wherein R4 is selected from the group consisting of monocyclic aromatic, polycyclic aromatic, monocyclic heteroaromatic, polycyclic heteroaromatic, 1° alkyl, and alkenyl, all of which are optionally substituted at one or more substitutable positions with one or more suitable substituents, and wherein R4 is bonded to the 2-position of the indole ring via a C-C bond; the process comprising reacting an ortho-gem-dihalovinylaniline compound of the formula (I): wherein Halo comprises Br, Cl, or I; each of the one or more R1 is independently selected from the group consisting of H, fluoro, lower alkyl, lower alkenyl, lower alkoxy, aryloxy, lower haloalkyl, lower alkenyl, -C(O)O-lower alkyl, monocyclic or polycyclic aryl or heteroaryl moiety, or R1 is an alkenyl group bonded so to as to form a 4- to 20-membered fused monocycle or polycyclic ring with the indole ring; all of which are optionally substituted with one or more suitable substituents at one or more substitutable positions; R2 comprises H, alkyl, cycloalkyl, aryl, heteroaryl, aryl-loweralkyl-, or heteroaryl-loweralkyl-, all of which are optionally substituted at one or more substitutable positions with one or more suitable substituents; R3 comprises H, alkyl, haloalkyl, alkenyl, alkynyl, aryl, heteroaryl, cycloalkyl, heterocycle, aryl-(C1-6)alkyl-, or heteroaryl-loweralkyl-, all of which are optionally substituted at one or more substitutable positions with one or more suitable substituents; with an organoboron reagent selected from the group consisting of a boronic ester of R4, a boronic acid of R4, a boronic acid anhydride of R4, a trialkylborane of R4 and a 9-BBN derivative of R4; in the presence of a base, a palladium metal pre-catalyst and a ligand under reaction conditions effective to form the 2-substituted indole compound. Also disclosed are processes for the preparation of ortho-gem-dihalovinylaniline compounds. Novel compounds prepared by the processes and novel uses of the compounds are likewise disclosed.
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Page/Page column 70; 123-124
(2010/11/08)
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- Pd-catalyzed tandem C-N/C-C coupling of gem-dihalovinyl systems: A modular synthesis of 2-substituted indoles
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(Chemical Equation Presented) 2-Substituted indoles were synthesized via a Pd-catalyzed tandem C-N/Suzuki-Miyaura coupling from readily prepared ortho-gem-dihalovinylanilines. Optimal conditions used a Pd(OAc) 2/S-Phos catalyst in the presence of K3PO 4·H2O and an organoboron reagent, which included boronic acids, esters, alkyl 9-BBN derivatives, and trialkylboranes. Yields of the desired indoles were good to excellent using low catalyst loadings (typically 1 mol %).
- Fang, Yuan-Qing,Lautens, Mark
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p. 3549 - 3552
(2007/10/03)
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- Direct palladium-catalyzed C-2 and C-3 arylation of indoles: A mechanistic rationale for regioselectivity
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We have recently developed palladium-catalyzed methods for direct arylation of indoles (and other azoles) wherein high C-2 selectivity was observed for both free (NH)-indole and (NR)-indole. To provide a rationale for the observed selectivity ("nonelectrophilic" regioselectivity), mechanistic studies were conducted, using the phenylation of 1-methylindole as a model system. The reaction order was determined for iodobenzene (zero order), indole (first order), and the catalyst (first order). These kinetic studies, together with the Hammett plot, provided a strong support for the electrophilic palladation pathway. In addition, the kinetic isotope effect (KIEH/D) was determined for both C-2 and C-3 positions. A surprisingly large value of 1.6 was found for the C-3 position where the substitution does not occur (secondary KIE), while a smaller value of 1.2 was found at C-2 (apparent primary KIE). On the basis of these findings, a mechanistic interpretation is presented that features an electrophilic palladation of indole, accompanied by a 1,2-migration of an intermediate palladium species. This paradigm was used to design new catalytic conditions for the C-3 arylation of indole. In case of free (NH)-indole, regioselectivity of the arylation reaction (C-2 versus C-3) was achieved by the choice of magnesium base.
- Lane, Benjamin S.,Brown, Meghann A.,Sames, Dalibor
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p. 8050 - 8057
(2007/10/03)
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- Three-component indole synthesis using ortho-dihaloarenes
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A three-component synthesis of substituted indoles is accomplished starting from ortho-dihaloarenes through the use of a multicatalytic system consisting of an N-heterocyclic carbene palladium complex and CuI. The corresponding indole derivatives are obtained as single regioisomers in high yields of isolated product.
- Kaspar, Ludwig T.,Ackermann, Lutz
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p. 11311 - 11316
(2007/10/03)
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- Direct C-H bond arylation: Selective palladium-catalyzed C2-arylation of N-substituted indoles
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(Equation Presented) We present a new, practical method by which N-substituted indoles may be selectively arylated in the C2-position with good yields, low catalyst loadings, and a high degree of functional group tolerance. Our investigation found that two competitive processes, namely, the desired cross-coupling and biphenyl formation, were operative in this reaction. A simple kinetic model was formulated that proved to be instructive and provided useful guidelines for reaction optimization; the approach described within may prove to be useful in other catalytic cross-coupling processes.
- Lane, Benjamin S.,Sames, Dalibor
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p. 2897 - 2900
(2007/10/03)
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- The copper-catalyzed N-arylation of indoles
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A general method for the N-arylation of indoles using catalysts derived from Cul and trans-1,2-cyclohexanediamine (1a), trans-N,N′-dimethyl-1,2-cyclohexanediamine (2a), or N,N′-dimethyl-ethylenediamine (3) is reported. N-Arylindoles can be produced in high yield from the coupling of an aryl iodide or aryl bromide with a variety of indoles.
- Antilla, Jon C.,Klapars, Artis,Buchwald, Stephen L.
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p. 11684 - 11688
(2007/10/03)
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- Amination reactions of aryl halides with nitrogen-containing reagents mediated by palladium/imidazolium salt systems
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Nucleophilic N-heterocyclic carbenes have been conveniently used as catalyst modifiers in amination reactions involving aryl chlorides, aryl bromides, and aryl iodides with various nitrogen-containing substrates. The scope of a coupling process using a Pd(0) or Pd(II) source and an imidazolium salt in the presence of a base, KOtBu or NaOH, was tested using various substrates. The Pd2(dba)3/IPr·HCl (1, IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) system presents the highest activity with respect to electron-neutral and electron-rich aryl chlorides. The ligand is also effective for the synthesis of benzophenone imines, which can be easily converted to the corresponding primary amines by acid hydrolysis. Less reactive indoles were converted to N-aryl-substituted indoles using as supporting ligand the more donating SIPr·HCl (5, SIPr = 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene). The Pd(OAc)2/SIPr·HCl/NaOH system is efficient for the N-arylation of diverse indoles with aryl bromides. The general protocol developed has been applied successfully to the synthesis of a key intermediate in the synthesis of an important new antibiotic. Mechanistically, palladium-to-ligand ratio studies strongly support an active species bearing one nucleophilic carbene ligand.
- Grasa,Viciu,Huang,Nolan
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p. 7729 - 7737
(2007/10/03)
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- Reactions of Diarylnitrenium Ions with Electron Rich Alkenes: An Experimental and Theoretical Study
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Photolysis of N-(diphenylamino)-2,4,6-trimethylpyridinium tetrafluoroborate (1a) and N-[bis(4-methylphenyl)amino]-2,4,6-trimethylpyridinium salt (1b) gives products attributable to diarylnitrenium ion (Ar2N+, 2). The major products of these reactions include products from nucleophilic addition of various π-nucleophiles (e.g. electron rich alkenes) to the ortho and para positions of one of the phenyl rings. Nanosecond and EPR spectroscopy show that radicals also form. These radicals are thought to give rise to the diarylamines isolated as minor products from the photolysis of la and 1b. In addition to the para addition products and Ph2NH, N-phenylindoles and N-phenylindolinones are isolated when silyl enol ethers and silyl ketene acetals are used as trapping agents, respectively. The indoles and indolinones are generated from initial addition of the nucleophile to the ortho position on 2 followed by cyclization of the resulting intermediate. A product resulting from N addition of the nucleophile to 2 is isolated only when silyl ketene acetals are used. A number of electronic sturcture calculations at different levels of molecular orbital and density functional theory were carried out on Ph2N+. There do not seem to be effects associated with either the charge distribution or the LUMO that would strongly influence ortho/para/N selectivity in nucleophilic trapping. Laser flash photolysis on la provides absolute rate constants for the nucleophilic addition of various alkenes to Ph2N+. These fall in the range of 109-1010 M-1 s-1 and correlate with the oxidation potential of the alkene. From these data it is clear that the more easily oxidized the alkene the faster it will react with Ph2N+.
- Moran, Ricardo J.,Cramer, Christopher,Falvey, Daniel E.
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p. 2742 - 2751
(2007/10/03)
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