- Synthesis of 2-aryl-2H-indazoles by base catalysed reaction of 2-nitrobenzyl triphenylphosphonium bromide and aryl isocyanates
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The synthesis of a series of 2-aryl-2H-indazoles is reported. These compounds are obtained in moderate to good yield by reaction of 2-nitrobenzyl triphenylphosphonium bromide with aryl isocyanates, catalysed by sodium hydride or DBU. (C) 2000 Elsevier Science Ltd.
- Taher,Ladwa,Rajan,Weaver
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- Direct Formation of 2-Substituted 2 H-Indazoles by a Pd-Catalyzed Reaction between 2-Halobenzyl Halides and Arylhydrazines
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A direct and operationally simple method for the regioselective synthesis of 2-aryl-substituted 2H-indazoles is reported. The Pd-catalyzed reaction between easily available 2-bromobenzyl bromides and arylhydrazines employing Cs2CO3 as the base and t-Bu3PHBF4 as the ligand in DMSO at 120 °C in a sealed tube delivers the 2-substituted-2H-indazoles in a single synthetic step with yields up to 79%. The new method is based on a regioselective intermolecular N-benzylation followed by intramolecular N-arylation and oxidation.
- Aljaar, Nayyef,Al-Noaimi, Mousa,Conrad, Jürgen,Beifuss, Uwe
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p. 1408 - 1418
(2021/01/14)
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- Metal-free regioselective C-H amination for the synthesis of pyrazole-containing 2H-indazoles
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A general and practical regioselective approach for the C-H amination of 2H-indazoles under transition-metal-free conditions was developed. A series of substrates were tested showing eminent functional group tolerance and affording the C-N functionalization products in good to excellent yields. Mechanism studies revealed that a radical process was involved in this transformation.
- Wang, Kai,Wei, Tingting,Zhang, Yujia,Hou, Jiahao,Bai, Renren,Xie, Yuanyuan
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p. 1787 - 1794
(2021/03/14)
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- Direct C3 Carbamoylation of 2H-Indazoles
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We developed a novel method for direct C3 carbamoylation of 2H-indazoles using oxamic acids as carbamoyl radical sources. In the presence of ammonium persulfate, carbamoyl radicals were generated from oxamic acids, then used for further reactions with 2H-indazoles to afford the desired products. The reaction proceeds under metal- and catalyst-free conditions. This simple process allows for the efficient synthesis of C3 carbamoylated 2H-indazoles, which are important scaffolds in organic synthesis.
- Bhat, Vighneshwar Shridhar,Lee, Anna
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supporting information
p. 3382 - 3385
(2021/06/28)
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- Synthesis, antiprotozoal activity, and cheminformatic analysis of 2-phenyl-2h-indazole derivatives
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Indazole is an important scaffold in medicinal chemistry. At present, the progress on synthetic methodologies has allowed the preparation of several new indazole derivatives with interesting pharmacological properties. Particularly, the antiprotozoal activity of indazole derivatives have been recently reported. Herein, a series of 22 indazole derivatives was synthesized and studied as antiprotozoals. The 2-phenyl-2H-indazole scaffold was accessed by a one-pot procedure, which includes a combination of ultrasound synthesis under neat conditions as well as Cadogan’s cyclization. Moreover, some compounds were derivatized to have an appropriate set to provide structure-activity relationships (SAR) information. Whereas the antiprotozoal activity of six of these compounds against E. histolytica, G. intestinalis, and T. vaginalis had been previously reported, the activity of the additional 16 compounds was evaluated against these same protozoa. The biological assays revealed structural features that favor the antiprotozoal activity against the three protozoans tested, e.g., electron withdrawing groups at the 2-phenyl ring. It is important to mention that the indazole derivatives possess strong antiprotozoal activity and are also characterized by a continuous SAR.
- Aguilera-Perdomo, Jacobo David,Cortés-Benítez, Francisco,Cortés-Gines, Miguel,Del Angel, Kevin Samael Olascoaga,Pérez-Villanueva, Jaime,Palacios-Espinosa, Juan Francisco,Quintana-Salazar, Edgar A.,Rodríguez-Villar, Karen,Soria-Arteche, Olivia,Yépez-Mulia, Lilián
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- Manganese-Catalyzed Electrochemical Tandem Azidation-Coarctate Reaction: Easy Access to 2-Azo-benzonitriles
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A one-pot cascade transformation consisting of an electrochemically driven azidation of 2H-indazole followed by coarctate fragmentation is developed to synthesize the 2-azo-benzonitrile motif. This manganese-catalyzed transformation is external-chemical-oxidant-free and operates at ambient temperature under air. This methodology exhibits good functional group tolerance, affording a broad range of substrate scopes of up to 89% isolated yield. Diverse derivatization of the 2-azo-benzonitrile product resulted in other valuable scaffolds.
- Maiti, Debabrata,Mahanty, Kingshuk,De Sarkar, Suman
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p. 1742 - 1747
(2021/04/05)
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- Oxidative cross-dehydrogenative coupling (CDC)viaC(sp2)-H bond functionalization:tert-butyl peroxybenzoate (TBPB)-promoted regioselective direct C-3 acylation/benzoylation of 2H-indazoles with aldehydes/benzyl alcohols/styrenes
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An efficient, cost-effective, transition-metal-free, oxidative C(sp2)-H/C(sp2)-H cross-dehydrogenative couplingviaa C(sp2)-H bond functionalization protocol for the regioselective direct C-3 acylation/benzoylation of subst
- Sharma, Richa,Yadav, Lalit,Yadav, Ravi Kant,Chaudhary, Sandeep
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p. 14178 - 14192
(2021/04/22)
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- Efficient synthesis of 2-aryl-2: H -indazoles by base-catalyzed benzyl C-H deprotonation and cyclization
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A straightforward and efficient method for the preparation of 2-aryl-2H-indazoles from ortho-alkyl substituted azoxybenzenes is presented. The reaction proceeds through base-catalyzed benzyl C-H deprotonation and cyclization to afford 2-aryl-2H-indazoles
- Gao, Wen-Xia,Jin, Guo-Qing,Liu, Miao-Chang,Wu, Hua-Yue,Zhou, Yun-Bing
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p. 14617 - 14620
(2020/12/02)
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- Tert-Butyl Hydroperoxide-Mediated Oxo-Sulfonylation of 2 H-Indazoles with Sulfinic Acid toward Indazol-3(2 H)-ones
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A new and efficient oxo-sulfonylation protocol has been established for the synthesis of N-sulfonylated indazolones employing sulfinic acid as a sulfonylating agent using tert-butyl hydroperoxide (TBHP) under ambient air. A series of structurally diverse 1-sulfonylindazol-3(2H)-one derivatives were obtained in good yields. A radical reaction mechanism has been proposed for this transformation.
- Ghosh, Payel,Mondal, Susmita,Hajra, Alakananda
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supporting information
p. 1086 - 1090
(2020/02/04)
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- Fe2O3@[proline]–CuMgAl–LDH: A magnetic bifunctional copper and organocatalyst system for one-pot synthesis of quinolines and 2H-indazoles in green media
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A novel magnetic core–shell Fe2O3@[proline]–CuMgAl–L(ayered)D(ouble)H(ydroxide) was designed as an efficient bifunctional catalytic system. To this end, Cu (II) was combined with Mg and Al in the LDH structure and l-proline was intercalated between LDH layers in order to perform a straightforward synthesis of quinolines and 2H-indazoles as two important pharmaceutical N-aryl-substituted heterocyclic compounds. In this regard, a facile method was employed through consecutive condensation under a mild conditions in choline azide media, which played the role of a reagent and a solvent to avoid toxic solvents and hazardous azidation reagents. These techniques provided considerable improvement in terms of using green media, reducing starting materials, reaching higher yields and offering a shorter reaction time and lower temperature. In conclusion, it was found that the catalyst could be reused five times with no significant loss of activity.
- Esfandiary, Naghmeh,Heydari, Akbar
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- Bu4NI-catalyzed, oxidative C(sp2)-C(sp3)cross dehydrogenative coupling for the regioselective direct C-3 benzylation of 2: H -indazoles
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A Bu4NI-catalyzed, DTBP-promoted, regioselective C(sp2)-C(sp3) cross dehydrogenative coupling (CDC) protocol for the direct C-3 benzylation of 2H-indazoles is reported. The metal-free protocol is operationally simple and proceeds mechanistically via the g
- Chaudhary, Sandeep,Yadav, Lalit
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p. 5927 - 5936
(2020/08/21)
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- Synthesis method of 2H-indazole and derivatives thereof
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The invention discloses a synthetic reaction of 2H-indazole and derivatives thereof under a metal-free condition. The new strategy has the advantages of no metal participation, wide substrate range and good functional group compatibility, and an efficient
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Paragraph 0027-0040
(2020/12/15)
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- Regioselective C3-H Trifluoromethylation of 2 H-Indazole under Transition-Metal-Free Photoredox Catalysis
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Trifluoromethyl-substituted heteroarenes are biologically active compounds and useful building blocks. In this sequence, we have developed a visible-light-promoted regioselective C3-H trifluoromethylation of 2H-indazole under metal-free conditions, which
- Murugan, Arumugavel,Babu, Venkata Nagarjuna,Polu, Ashok,Sabarinathan, Nagaraj,Bakthadoss, Manickam,Sharada, Duddu S.
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p. 7796 - 7803
(2019/06/27)
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- Visible-light-induced regioselective cross-dehydrogenative coupling of 2 H-indazoles with ethers
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A visible-light-promoted regioselective C(sp2)-H/C(sp3)-H cross-dehydrogenative coupling between 2H-indazoles and ethers has been achieved using a catalytic amount of rose bengal as an organophotoredox-catalyst and tert-butyl hydroperoxide (TBHP) as an oxidant at ambient temperature under aerobic conditions. A variety of C-3 oxyalkylated 2H-indazoles have been synthesized in moderate to good yields. Mechanistic studies suggest a radical pathway of the present reaction.
- Singsardar, Mukta,Laru, Sudip,Mondal, Susmita,Hajra, Alakananda
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p. 4543 - 4550
(2019/04/30)
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- Visible-light-mediated direct C3-arylation of 2: H -indazoles enabled by an electron-donor-acceptor complex
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A mild visible-light-mediated, photocatalyst-free arylation of 2H-indazoles was developed. The formation of an electron donor-acceptor complex by 2H-indazoles and aryl diazonium salts in the presence of pyridine allows the direct arylation of 2H-indazoles under visible-light irradiation. This process provides an efficient route for the synthesis of C3-arylated-2H-indazoles, which are important scaffolds of various bioactive compounds.
- Aganda, Kim Christopher C.,Kim, Junyoung,Lee, Anna
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supporting information
p. 9698 - 9702
(2019/12/02)
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- Assembly of Fully Substituted 2H-Indazoles Catalyzed by Cu2O Rhombic Dodecahedra and Evaluation of Anticancer Activity
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Simultaneous C?N, and N?N bond-forming methods for one-pot transformations are highly challenging in synthetic organic chemistry. In this study, the Cu2O rhombic dodecahedra-catalyzed synthesis of 2H-indazoles is demonstrated with good to excellent yields from readily available chemicals. This one-pot procedure involves Cu2O nanoparticle-catalyzed consecutive C?N, and N?N bond formation followed by cyclization to yield 2H-indazoles with broad substrate scope and high functional group tolerance. Various cell-based bioassay studies demonstrated that 2H-indazoles inhibit the growth of cancer cells, typically through induction of apoptosis in a dose-dependent manner. Moreover, 2H-indazoles tested in the MDA-MB-468 cell line were capable of inhibiting cancer cell migration and invasion. Thus, it is shown that 2H-indazoles have potent in vitro anticancer activity that warrant further investigation of this compound class.
- Panchangam, Rajeeva Lochana,Manickam, Venkatraman,Chanda, Kaushik
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p. 262 - 272
(2019/01/04)
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- Silica-supported Cu(II)–quinoline complex: Efficient and recyclable nanocatalyst for one-pot synthesis of benzimidazolquinoline derivatives and 2H-indazoles
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The synthesis, characterization and catalytic activity of a Cu(II) complex derived from 2-oxoquinoline-3-carbaldehyde Schiff base supported on amino-functionalized silica are reported. 3-(1H-Benzo[d]imidazol-2-yl)quinolines containing piperidine, morpholi
- Sharghi, Hashem,Aberi, Mahdi,Shiri, Pezhman
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- A General One-Pot Synthesis of 2H-Indazoles Using an Organophosphorus–Silane System
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A simple and direct approach for the regioselective construction of the privileged 2H-indazole scaffold is described. The developed one-pot strategy involves phospholene-mediated N?N bond formation to access 2H-indazoles. The amount of organophosphorus reagent was minimized by recycling the phospholene oxide with organosilane reductants. Starting from functionalized 2-nitrobenzaldehydes and primary amines, a mild reductive cyclization, involving the use of commercially available phospholene oxide and silanes, delivered a wide variety of substituted 2H-indazoles in good to excellent yields.
- Schoene, Jens,Bel Abed, Hassen,Schmieder, Peter,Christmann, Mathias,Nazaré, Marc
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p. 9090 - 9100
(2018/06/29)
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- Direct Acyl Radical Addition to 2 H-Indazoles Using Ag-Catalyzed Decarboxylative Cross-Coupling of α-Keto Acids
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A direct acyl radical addition to 2H-indazoles has been achieved for the first time, where the less-aromatic quinonoid 2H-indazoles readily accepted radical species to the C-3 position. Motivated by the lack of direct acylation strategy for 2H-indazoles, the current method utilizes the radical acceptability of 2H-indazoles, discovering an ambient temperature reaction to provide facile access to a diverse array of 3-acyl-2H-indazoles with three points of structural diversification in 25%-83% yields.
- Bogonda, Ganganna,Kim, Hun Young,Oh, Kyungsoo
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p. 2711 - 2715
(2018/05/22)
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- A Biphilic Phosphetane Catalyzes N-N Bond-Forming Cadogan Heterocyclization via PIII/PV = O Redox Cycling
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A small-ring phosphacycle, 1,2,2,3,4,4-hexamethylphosphetane, is found to catalyze deoxygenative N-N bond-forming Cadogan heterocyclization of o-nitrobenzaldimines, o-nitroazobenzenes, and related substrates in the presence of hydrosilane terminal reductant. The reaction provides a chemoselective catalytic synthesis of 2H-indazoles, 2H-benzotriazoles, and related fused heterocyclic systems with good functional group compatibility. On the basis of both stoichiometric and catalytic mechanistic experiments, the reaction is proposed to proceed via catalytic PIII/PV = O cycling, where DFT modeling suggests a turnover-limiting (3+1) cheletropic addition between the phosphetane catalyst and nitroarene substrate. Strain/distortion analysis of the (3+1) transition structure highlights the controlling role of frontier orbital effects underpinning the catalytic performance of the phosphetane.
- Nykaza, Trevor V.,Harrison, Tyler S.,Ghosh, Avipsa,Putnik, Rachel A.,Radosevich, Alexander T.
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p. 6839 - 6842
(2017/05/29)
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- Ultrasound promoted mild and facile onepot, three component synthesis of 2Hindazoles by consecutive condensation, CN and NN bond formations catalysed by copperdoped silica cuprous sulphate (CDSCS) as an efficient heterogeneous nanocatalyst
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An ultrasonic promoted facile and convenient one-pot three-component procedure for the synthesis of 2H-indazole derivatives using copper-doped silica cuprous sulphate (CDSCS) as a heterogeneous nano-catalyst has been described. In this approach, ultrasonic mediated reaction of different substituted 2-bromobenzaldehydes, structurally diverse primary amines, and tetrabutylammonium azide (TBAA) as an azide source in the presence of CDSCS in DMSO at room temperature furnishes 2H-indazoles in good to excellent yields. Utilizing ultrasonic irradiation techniques provided the dramatic improvements in terms of higher yields and shorter reaction times compared with conventional heating method.
- Soltani Rad, Mohammad Navid
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p. 865 - 872
(2016/08/11)
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- Highly Efficient One-Pot Three Component Synthesis of 2H-Indazoles by Consecutive Condensation, C–N and N–N Bond Formations Using Cu/Aminoclay/Reduced Graphene Oxide Nanohybrid
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A simple and straightforward one-pot three-component synthesis of 2H-indazoles through copper-catalyzed consecutive condensation, C–N and N–N bond formations of easily accessible starting materials under ligand-free conditions is described. In this protocol, treatment of substituted 2-bromobenzaldehydes, structurally diverse amines, and [bmim]N3 in the presence of Cu/aminoclay/reduced graphene oxide nanohybrid (Cu/AC/r-GO nanohybrid) as an efficient heterogeneous catalyst affords the corresponding 2H-indazoles in good to excellent yields. The influence of effective parameters on the efficient progress of the reaction was studied. The Cu/AC/r-GO nanohybrid is a stable and inexpensive catalyst that could be simply prepared, recovered, and reused for several reaction runs with no significant decrease in its reactivity.
- Behrouz, Somayeh
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p. 1863 - 1871
(2017/05/29)
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- Highly reusable support-free copper(II) complex of para-hydroxy-substituted salen: Novel, efficient and versatile catalyst for C─N bond forming reactions
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An air-stable, highly active and versatile method for C─N bond forming reactions is reported. Under mild conditions using a highly reusable support-free Cu(II)–salen complex, structurally diverse N-aryl-substituted compounds were obtained via direct C─N bond forming reaction of HN-heterocycles with aryl iodides or three-component C─N bond forming reaction of 2-bromobenzaldehyde, aniline derivatives and sodium azide in good to excellent yields. C─N bond forming reaction for benzimidazole derivatives was also performed in the presence of the catalyst under ambient conditions. A series of hybrid benzimidazoles bearing morpholine, tetrazole and quinoxaline backbones were produced using this method. All reactions were performed in short times under air. The Cu(II) catalyst could be reused up to eight times in the direct cross-coupling reaction of 9H–carbazole with iodobenzene without any decrease in its catalytic activity.
- Sharghi, Hashem,Aberi, Mahdi,Shiri, Pezhman
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- Synthesis and biological evaluation of 2H-indazole derivatives: Towards antimicrobial and anti-inflammatory dual agents
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Indazole is considered a very important scaffold in medicinal chemistry. It is commonly found in compounds with diverse biological activities, e.g., antimicrobial and anti-inflammatory agents. Considering that infectious diseases are associated to an inflammatory response, we designed a set of 2H-indazole derivatives by hybridization of cyclic systems commonly found in antimicrobial and anti-inflammatory compounds. The derivatives were synthesized and tested against selected intestinal and vaginal pathogens, including the protozoa Giardia intestinalis, Entamoeba histolytica, and Trichomonas vaginalis; the bacteria Escherichia coli and Salmonella enterica serovar Typhi; and the yeasts Candida albicans and Candida glabrata. Biological evaluations revealed that synthesized compounds have antiprotozoal activity and, in most cases, are more potent than the reference drug metronidazole, e.g., compound 18 is 12.8 times more active than metronidazole against G. intestinalis. Furthermore, two 2, 3-diphenyl-2H-indazole derivatives (18 and 23) showed in vitro growth inhibition against Candida albicans and Candida glabrata. In addition to their antimicrobial activity, the anti-inflammatory potential for selected compounds was evaluated in silico and in vitro against human cyclooxygenase-2 (COX-2). The results showed that compounds 18, 21, 23, and 26 display in vitro inhibitory activity against COX-2, whereas docking calculations suggest a similar binding mode as compared to rofecoxib, the crystallographic reference.
- Pérez-Villanueva, Jaime,Yépez-Mulia, Lilián,González-Sánchez, Ignacio,Palacios-Espinosa, Juan Francisco,Soria-Arteche, Olivia,Del Rosario Sainz-Espu?es, Teresita,Cerbón, Marco A.,Rodríguez-Villar, Karen,Rodríguez-Vicente, Ana Karina,Cortés-Gines, Miguel,Custodio-Galván, Zeltzin,Estrada-Castro, Dante B.
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- A mild and regioselective Ullmann reaction of indazoles with aryliodides in water
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A mild and regioselective Ullmann reaction of indazoles with aryliodides has been developed as a general method for the synthesis of 1-aryl-1H-indazoles. Water was used as the solvent wherein Tween 20 (2% w/w) was added to form aqueous micelles to improve
- Ding, Xiao,Bai, Jingtao,Wang, Hailong,Zhao, Baowei,Li, Jian,Ren, Feng
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p. 172 - 178
(2016/12/23)
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- Indazolium halides as efficient ligands for Pd-catalyzed Suzuki–Miyaura cross-coupling of aryl bromides with arylboronic acids
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The indazolium halides containing various N-substituents have been conveniently prepared and applied in the palladium-catalyzed Suzuki–Miyaura cross-coupling reactions of aryl bromides with arylboronic acids at mild reaction conditions. The cross-coupling reaction provides the desired products in good to high yields. The ease of synthesis and the modularity, and the broad range of aryl bromides and arylboronic acids make this type of ligand attractive and promising for transition metal catalysis.
- Chen, Qian,Mao, Zhuqing,Guo, Fang,Liu, Xiaoshuang
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supporting information
p. 3735 - 3738
(2016/07/26)
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- A Facile One-Step Synthesis of 2-Arylindazoles via Reductive Cyclization of N-(2-nitroarylidene)amines
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A mild and efficient synthesis of 2-arylindazole derivatives via the reductive cyclization of nitro-aryl substrates mediated by a low-valent titanium reagent (TiCl4/Sm/Et3N) has been developed. The attractive features of the current method include an N-N bond formation and the selective reduction of the =C-N bond and nitro group, both of which were easily achieved in one-pot by controlling the pH of the reaction mixture.
- Lin, Wei,Hu, Minghua,Feng, Xian,Cao, Chengpao,Huang, Zhibin,Shi, Daqing
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p. 1170 - 1174
(2015/08/06)
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- Ligand-free Copper(I) oxide nanoparticle catalyzed three-component synthesis of 2 H -indazole derivatives from 2-halobenzaldehydes, amines and sodium azide in polyethylene glycol as a green solvent
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An efficient synthesis of 2H-indazole derivatives based on the one-pot three-component reaction of 2-chloro- and 2-bromobenzaldehydes, primary amines and sodium azide is described. The reaction is catalyzed by copper(I) oxide nanoparticles (Cu2O-NP) under ligand-free conditions in polyethylene glycol (PEG 300) as a green solvent. Georg Thieme Verlag Stuttgart New York.
- Sharghi, Hashem,Aberi, Mahdi
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supporting information
p. 1111 - 1115
(2014/05/20)
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- Regioselective synthesis of 2 H-indazoles using a mild, one-pot condensation-cadogan reductive cyclization
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An operationally simple and efficient one-pot synthesis of 2H-indazoles from commercially available reagents is reported. Ortho-imino-nitrobenzene substrates, generated via condensation, undergo reductive cyclization promoted by tri-n-butylphosophine to afford substituted 2H-indazoles under mild reaction conditions. A variety of electronically diverse ortho-nitrobenzaldehydes and anilines were examined. To further extend the scope of the transformation, aliphatic amines were also employed to form N2-alkyl indazoles selectively under the optimized reaction conditions.
- Genung, Nathan E.,Wei, Liuqing,Aspnes, Gary E.
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p. 3114 - 3117
(2014/06/23)
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- Metal acetylacetonates covalently anchored onto amine functionalized silica/starch composite for the one-pot thioetherification and synthesis of 2H-indazoles
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This paper reports a series of novel metal acetylacetonates covalently anchored onto amine functionalized silica/starch composite, prepared by the Schiff condensation of metal acetylacetonates [Co(acac)2, Cu(acac)2, Pd(acac)2, Ru(acac)3, Mn(acac)3, Co(acac)3] with organically modified 3-aminopropyl silica/starch composite. Different metal acetylacetonates have been chosen with a view to select the most active heterogeneous catalyst. Among various catalysts, covalently anchored Cu(acac)2 onto amine functionalized silica/starch composite [ASS-Cu(acac)2] was found to be the most active and recyclable catalyst for the one-pot thioetherification and one-pot three component synthesis of 2H-indazoles via consecutive C-N and N-N bond formations. All the catalysts were characterized by FTIR, TGA and AAS analysis and the most active catalyst, [ASS-Cu(acac)2] was further characterized by SEM and TEM. The catalyst could be recovered by simple filtration and reused with almost consistent activity for four consecutive runs.
- Sodhi, Ravinderpal Kour,Changotra, Avtar,Paul, Satya
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p. 1819 - 1831
(2015/02/19)
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- CuO nanoparticle catalysed synthesis of 2H-indazoles under ligand free conditions
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A CuO nano catalysed one-pot synthesis of 2H-indazoles has been devised from easily accessible starting materials viz. 2-bromobenzaldehydes, primary amines and sodium azide under ligand free conditions. The nano CuO catalyst played an important role during the formation of the intermolecular C-N bond followed by the intramolecular N-N bond, providing 2H-indazoles. This method has a broad substrate scope with a high tolerance of a variety of functional groups. The catalyst can be recycled up to three times, however with slight decreases in the yields each time.
- Khatun, Nilufa,Gogoi, Anupal,Basu, Pallabita,Das, Prasenjit,Patel, Bhisma K.
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p. 4080 - 4084
(2014/01/06)
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- Microwave-assisted molybdenum-catalyzed reductive cyclization of o -nitrobenzylidene amines to 2-Aryl-2 H -indazoles
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The reductive cyclization of o-nitrobenzylidene amines under microwave conditions employing MoO2Cl2(dmf)2 as catalyst and Ph3P as reducing agent delivers 2-aryl-2H-indazoles with yields ranging from 61-92%. Georg Thieme Verlag Stuttgart. New York.
- Moustafa, Ahmed H.,Malakar, Chandi C.,Aljaar, Nayyef,Merisor, Elena,Conrad, Jürgen,Beifuss, Uwe
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p. 1573 - 1577
(2013/08/23)
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- CuII-hydrotalcite catalyzed one-pot three component synthesis of 2H-indazoles by consecutive condensation, C-N and N-N bond formations
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An efficient and straightforward synthesis of 2H-indazoles is achieved from 2-bromobenzaldehydes, primary amines and sodium azide through consecutive condensation, C-N and N-N bond formations, catalyzed by a novel heterogeneous CuII-HT catalyst. The recoverable heterogeneous CuII-HT catalyst exhibited an impressive activity for the title reaction without any additives (expensive ligands, etc.). Heterocyclization proceeds through C-N and N-N bond formation, which is the key step to deliver the desired 2H-indazole scaffold. A series of structurally diverse 2H-indazoles were prepared in good to excellent yields from easily accessible starting materials by employing this protocol.
- Prasad, Avvari N.,Srinivas, Rapelli,Reddy, Benjaram M.
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p. 654 - 658
(2013/03/28)
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- An efficient synthesis of 2H-indazoles via reductive cyclization of 2-nitrobenzylamines induced by low-valent titanium reagent
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An efficient and improved synthesis of 2H-indazoles via reductive cyclization of 2-nitrobenzylamines induced by low-valent titanium reagent (TiCl4/Zn) is described. In this reaction triethylamine (TEA) was used to control the pH value. This met
- Sun, Fang,Feng, Xian,Zhao, Xuan,Huang, Zhi-Bin,Shi, Da-Qing
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experimental part
p. 3851 - 3855
(2012/06/30)
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- A general and efficient approach to 2H-indazoles and 1H-pyrazoles through copper-catalyzed intramolecular N-N bond formation under mild conditions
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A new efficient copper-catalyzed intramolecular amination reaction has been developed to readily synthesise a wide variety of multi-substituted 2H-indazole and 1H-pyrazole derivatives from easily accessible starting materials under mild conditions. A highly selective ligand for estrogen receptor β was prepared in three steps by employing this method. The Royal Society of Chemistry 2011.
- Hu, Jiantao,Cheng, Yongfeng,Yang, Yiqing,Rao, Yu
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p. 10133 - 10135
(2011/10/09)
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- Mild, base-free copper-catalyzed N-arylations of heterocycles using potassium aryltrifluoroborates in water under air
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An economic, mild and efficient copper-catalyzed methodology for the N-arylation of heterocycles was optimized using potassium aryltrifluoroborates in water.
- Joubert, Nicolas,Baslé, Emmanuel,Vaultier, Michel,Pucheault, Mathieu
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supporting information; experimental part
p. 2994 - 2997
(2010/07/10)
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- Synthesis of 2-aryl-2H-indazoles via copper(I)-catalyzed intramolecular amination reaction
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A versatile method for the preparation of 2-aryl-2H-indazoles was developed by copper(I)-catalyzed intramolecular amination reaction under the conditions of [CuI/Cs2CO3(250 mol%)/1,4-dioxane/105°C] starting from N'-aryl-N'-(o-bromobe
- Liu, Rui,Zhu, Yong-ming,Qin, Lie-na,Ji, Shun-jun,Katayama, Haji
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p. 1755 - 1763
(2008/03/14)
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- Pyrazoles for the treatment of obesity and other CNS disorders
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This invention relates to compounds having pharmacological activity, to compositions containing these compounds, and to a method of treatment employing the compounds and compositions. More particularly, this invention concerns certain pyrazole derivatives, their salts and solvates. These compounds have H3 histamine receptor binding activity. This invention also relates to pharmaceutical compositions containing these compounds and to a method of treating disorders in which histamine H3 receptor modulation is beneficial.
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(2010/11/28)
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- A novel and efficient synthesis of 2-aryl-2H-indazoles via SnCl 2-mediated cyclization of 2-nitrobenzylamines
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A mild, efficient, and novel synthesis of 2-aryl-2H-indazoles via cyclization of 2-nitrobenzylamines promoted by SnCl2·2H 2O has been described. This method applies to a wide scope of substrates containing electron-donating and elect
- Shi, Da-Qing,Dou, Guo-Lan,Ni, Sai-Nan,Shi, Jing-Wen,Li, Xiao-Yue,Wang, Xiang-Shan,Wu, Hui,Ji, Shun-Jun
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p. 2509 - 2512
(2008/02/13)
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- Microwave enhanced greener synthesis of indazoles via nitrenes
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Non-traditional methods (grinding, water-based biphasic reactions, microwave chemistry) were used for the preparation of Schiff bases from several amines and 2-nitrobenzaldehydes. These nitro compounds were allowed to react with triethyl phosphite under m
- Varughese, Deepu John,Manhas, Maghar S.,Bose, Ajay K.
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p. 6795 - 6797
(2007/10/03)
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- A novel synthesis of 2-aryl-2H-indazoles via a palladium-catalyzed intramolecular amination reaction.
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[reaction: see text] A variety of 2-aryl-2H-indazoles were synthesized by the palladium-catalyzed intramolecular amination of the corresponding N-aryl-N(o-bromobenzyl)hydrazines. Of several sets of reaction conditions surveyed, the combination of Pd(OAc)2
- Song,Yee
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p. 519 - 521
(2007/10/03)
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- Synthesis and electrochemical behaviour of 2-N-substituted indazoles
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A new 2-N-aryl-3-methoxycarbonylindazole synthesis from the 6 F mol-1 reduction of appropriately substituted aryl-nitrones has been developed. The indazoles bearing an electron withdrawing group in the 2-position are electroreducible compounds at high negative potentials producing selectively the corresponding 2-N-substituted indazolines in aqueous alcoholic medium. The nitrile and ester groups are not reduced under the reaction conditions. Three new 2-N-arylindazolines were synthesized and characterized. A second electron withdrawing group attached at the 3-position leads to a less cathodic reduction of the 2-N-aryl-3-methoxycarbonylindazole. An appropriately substituted indazoline was used to generate in situ a new tetracyclic heterocycle.
- Frontana-Uribe,Moinet
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p. 814 - 823
(2007/10/03)
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- 2-substituted indazoles from electrogenerated ortho-nitrosobenzylamines
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An electrochemical methodology for an efficient access to ortho- nitrosobenzylamines has been developed. These products cyclize intramolecularly producing the desired 2-substituted indazoles in high yields. The electrochemical procedure overcomes limitations of previous chemical methods.
- Frontana-Uribe, Bernardo A.,Moinet, Claude
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p. 3197 - 3206
(2007/10/03)
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