- Targeting GluN2B-containing N-methyl- D -aspartate receptors: Design, synthesis, and binding affinity evaluation of novel 3-substituted indoles
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In an effort to improve our knowledge about structure-affinity relationships (SARs) for a class of 3-substituted-indole derivatives as GluN2B-containing N-methyl-D-aspartate-type receptor (NMDAR) ligands, we herein describe the design, synthesis, and preliminary screening of a new series of molecules. The in vitro determination of binding affinities suggested that 5-hydroxy- and 6-hydroxyindole derivatives 12 and 13 were active ligands. Generally, the novel compounds proved to be less potent than their homologs previously reported as promising neuroprotective agents. In fact, our lead compound 3-(4-benzylpiperidin-1-yl)-1-(5-hydroxy-1H-indol-3-yl)ethan-1-one (2) was about 10-fold more active than the new propan-1-one derivative (12). To rationalize the low potency of the new analog 12, docking studies were also performed and the in silico results were consistent with the in vitro data.
- Buemi, Maria Rosa,De Luca, Laura,Ferro, Stefania,Gitto, Rosaria
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Read Online
- Cascade Reaction to Selectively Synthesize Multifunctional Indole Derivatives by IrIII-Catalyzed C?H Activation
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An effective and condition-controlled way to synthesize with high selectivity a variety of functionalized indoles with potent biological properties has been developed. Notably, 2,4-dialkynyl indole products were obtained by direct double C?H bond alkynylation, whereas alkynyl at the C4 position could convert to carbonyl to generate 2-alkynyl-3,4-diacetyl indoles fast and effectively. Additionally, a one-pot relay catalytic reaction led to 2,5-di-alkynyl-3,4-diacetyl indoles when using a carbonyl group as the directing group and by controlling the type and quantity of additives. A possible mechanism was proposed based on many studies including deuterium-exchange experiments, the necessary conditions of product conversion, and the effect of water on the reaction.
- Chai, Xin-Yue,Xu, Hui-Bei,Dong, Lin
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supporting information
p. 13123 - 13127
(2021/08/13)
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- Indole-Containing Amidinohydrazones as Nonpeptide, Dual RXFP3/4 Agonists: Synthesis, Structure–Activity Relationship, and Molecular Modeling Studies
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The central relaxin-3/RXFP3 system plays important roles in stress responses, feeding, and motivation for reward. However, exploration of its therapeutic applications has been hampered by the lack of small molecule ligands and the cross-activation of RXFP1 in the brain and RXFP4 in the periphery. Herein, we report the first structure–activity relationship studies of a series of novel nonpeptide amidinohydrazone-based agonists, which were characterized by RXFP3 functional and radioligand binding assays. Several potent and efficacious RXFP3 agonists (e.g., 10d) were identified with EC50 values 100-fold selectivity for RXFP3/4 over RXFP1. In vitro ADME and pharmacokinetic assessments revealed that the amidinohydrazone derivatives may have limited brain permeability. Collectively, our findings provide the basis for further optimization of lead compounds to develop a suitable agonist to probe RXFP3 functions in the brain.
- Guan, Dongliang,Rahman, Md Toufiqur,Gay, Elaine A.,Vasukuttan, Vineetha,Mathews, Kelly M.,Decker, Ann M.,Williams, Alexander H.,Zhan, Chang-Guo,Jin, Chunyang
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p. 17866 - 17886
(2021/12/13)
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- Synthesis and antibacterial evaluation of (E)-1-(1H-indol-3-yl) ethanone O-benzyl oxime derivatives against MRSA and VRSA strains
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Infections caused due to multidrug resistant organisms have emerged as a constant menace to human health. Even though numerous antibiotics are currently available for treating infectious diseases, a great number of bacterial strains have acquired resistance to many of them. Among these, infections caused due to Staphylococcus aureus are predominant in adult and paediatric population. Indole is a prominent chemical scaffold found in many pharmacologically active natural products and synthetic drugs. A number of oxime ether containing compounds have attracted attention of researchers owing to their interesting biological properties. Current work details the synthesis of indole containing oxime ether derivatives and their evaluation for antimicrobial activity against a panel of bacterial and mycobacterial strains. Synthesized compounds demonstrated good to moderate activity against drug-resistant S. aureus including resistant to vancomycin. Among all, compound 5h was found to possess potent activity against susceptible as well as MRSA and VRSA strains of S. aureus with MIC of 1 μg/mL and 2–4 μg/mL respectively. In addition, compound 5h was found to be non-toxic to Vero cells and exhibited good selectivity index of >40. Further, 5h, E-9a and E-9b possessed good biofilm inhibition against S. aureus. With these assuring biological properties, synthesized compounds could be potential prospective antimicrobial agents.
- Akunuri, Ravikumar,Veerareddy, Vaishnavi,Kaul, Grace,Akhir, Abdul,Unnissa, Tanveer,Parupalli, Ramulu,Madhavi,Chopra, Sidharth,Nanduri, Srinivas
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- NbCl5 and AgClO4 promoted regio-selective acylation of indoles
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In present study, an efficient and simple strategy towards chemo-selective and regio-selective acylation of indole using NbCl5 and AgClO4 catalyst are reported. This method utilizes the catalytic potentiality of NbCl5 and AgClO4 towards acylation of unprotected indoles in a synergistic manner. The combination of these catalytic system results into numerous advantages such as excellent yields of product, short reaction times and easier isolation of products.
- Kamble, Narendra R.,Pawar, Hari R.,Kamble, Vinod T.
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p. 317 - 321
(2020/01/08)
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- Ketone-Directed Cobalt(III)-Catalyzed Regioselective C2 Amidation of Indoles
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An efficient cobalt(III)-catalyzed method for the direct C-H amidation of unprotected indoles for 2-amino indole scaffold construction has been developed. With dioxazolone as the amidating reagent, a variety of 2-amino indole derivatives were achieved in moderate to excellent yields using an organic acid as the additive and a ketone as the directing group.
- Shi, Xinxia,Xu, Weiyan,Wang, Rongchao,Zeng, Xiaofei,Qiu, Huayu,Wang, Min
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p. 3911 - 3920
(2020/03/23)
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- Weak Coordination-Guided Regioselective Direct Redox-Neutral C4 Allylation of Indoles with Morita-Baylis-Hillman Adducts
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A weak carbonyl coordination-guided regioselective C4 allylation of indoles is demonstrated using the versatile Morita-Baylis-Hillman adduct in the presence of Rh catalysts in a redox-neutral fashion. The substrate scope, functional group diversity, oxidant free character, mechanistic aspects, and synthetic utilities are important practical features.
- Pradhan, Sourav,De, Pinaki Bhusan,Punniyamurthy, Tharmalingam
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supporting information
p. 9898 - 9903
(2019/12/24)
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- Feasible selective synthesis of 3-Acetylindoles and 3-Acetoacetylindoles from β-ethylthio-β-indoly α, β-unsaturated ketones
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An efficient and selective synthesis of 3-acetyl free(N-H)/N-substituded indoles and 3-acetoacetyl free(N-H)/N-substituded indoles has been developed via the hydrolysis reaction of β-ethylthio-β-indoly α, β-unsaturated ketones in the presence of 3 equivalent of NaOH and 5 mol% of H2SO4, respectively. The procedure features easy operation, excellent yields, and high selectivity, compatibility and practicability.
- Wang, Wen-Ju,Yu, Hai-Feng
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p. 377 - 385
(2019/02/07)
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- Optimization, Structure-Activity Relationship, and Mode of Action of Nortopsentin Analogues Containing Thiazole and Oxazole Moieties
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Plant diseases seriously endanger plant health, and it is very difficult to control them. A series of nortopsentin analogues were designed, synthesized, and evaluated for their antiviral activities and fungicidal activities. Most of these compounds displayed higher antiviral activities than ribavirin. Compounds 1d, 1e, and 12a, with excellent antiviral activities, emerged as novel antiviral lead compounds, among which 1e was selected for further antiviral mechanism research. The mechanism research results indicated that these compounds may play an antiviral role by aggregating viral particles to prevent their movement in plants. Further fungicidal activity tests revealed that nortopsentin analogues displayed broad-spectrum fungicidal activities. Compounds 2p and 2f displayed higher antifungal activities against Alternaria solani than the commercial fungicides carbendazim and chlorothalonil. Current research has laid a foundation for the application of nortopsentin analogues in plant protection.
- Guo, Jincheng,Hao, Yanan,Ji, Xiaofei,Wang, Ziwen,Liu, Yuxiu,Ma, Dejun,Li, Yongqiang,Pang, Huailin,Ni, Jueping,Wang, Qingmin
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p. 10018 - 10031
(2019/10/05)
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- Expanding the SAR of Nontoxic Antiplasmodial Indolyl-3-ethanone Ethers and Thioethers
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Despite major strides in reducing Plasmodium falciparum infections, this parasite still accounts for roughly half a million annual deaths. This problem is compounded by the decreased efficacy of artemisinin combination therapies. Therefore, the development and optimisation of novel antimalarial chemotypes is critical. In this study, we describe our strategic approach to optimise a class of previously reported antimalarials, resulting in the discovery of 1-(5-chloro-1H-indol-3-yl)-2-[(4-cyanophenyl)thio]ethanone (13) and 1-(5-chloro-1H-indol-3-yl)-2-[(4-nitrophenyl)thio]ethanone (14), whose activity was equipotent to that of chloroquine against the P. falciparum 3D7 strain. Furthermore, these compounds were found to be nontoxic to HeLa cells as well as being non-haemolytic to uninfected red blood cells. Intriguingly, several of our most promising compounds were found to be less active against the isogenic NF54 strain, highlighting possible issues with long-term dependability of malarial strains. Finally compound 14 displayed similar activity against both the NF54 and K1 strains, suggesting that it inhibits a pathway that is uncompromised by K1 resistance.
- Lunga, Mayibongwe J.,Chisango, Ruramai L.,Weyers, Carli,Isaacs, Michelle,Taylor, Dale,Edkins, Adrienne L.,Khanye, Setshaba D.,Hoppe, Heinrich C.,Veale, Clinton G. L.
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p. 1353 - 1362
(2018/07/13)
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- Oxidative coupling of enolates using memory of chirality: An original enantioselective synthesis of quaternary α-amino acid derivatives
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We describe here the first enantioselective oxidative heterocoupling of enolates. Our strategy relies on the memory of chirality concept and allows the stereocontrolled formation of quaternary centres on α-amino acid derivatives with an enantiomeric excess of up to 94%.
- Mambrini, Antonin,Gori, Didier,Guillot, Régis,Kouklovsky, Cyrille,Alezra, Valérie
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supporting information
p. 12742 - 12745
(2018/12/01)
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- Rhodium(III)-Catalyzed Regioselective Direct C4-Alkylation and C2-Annulation of Indoles: Straightforward Access to Indolopyridone
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A straightforward RhIII-catalyzed strategy was developed for the site-selective C4-alkylation and C2-annulation of indole by using electronically variable diazo esters. The transformation was accomplished with the assist of an oxime directing group at the C3 position of the indole core with wide scope and functional-group tolerance. The method directly provided an indolopyridone core. The selectivity was triggered by the reactivity of the diazo coupling partner.
- Biswas, Aniruddha,Samanta, Rajarshi
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p. 1426 - 1436
(2018/04/06)
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- An efficient synthesis and biological evaluation of novel analogues of natural product Cephalandole A: A new class of antimicrobial and antiplatelet agents
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Cephalandole A 2, a small indole alkaloid isolated from the Taiwanese orchid Cephalanceropsis gracilis (Orchidaceae), exhibits anticancer activity. Surprisingly, this natural product has not been evaluated for any other biological activity so far. To discover other novel potential of Cephalandole A 2, an efficient and economic synthetic protocol for novel Cephalandole A analogues 21a-o has been developed, in only 3 steps from using indole, and applied for their biological activity. Biological testing showed that Cephalandole A 2 and its novel analogues 21a-o exhibited potential antimicrobial and antiplatelet activity in preliminary assay. To the best of our knowledge, this is the first report of Cephalandole A 2 and its novel synthetic analogues 21a-o as a new class of antimicrobial and antiplatelet agents. In this study, 2 and other analogues i.e., 21b, 21d, 21i and 21o showed promising antimicrobial activity against the phytopathogenic bacteria and fungi. Cephalandole A 2, 21c, 21f and 21i, also showed potent antiplatelet activity.
- Sharma, Vashundhra,Jaiswal, Pradeep K.,Kumar, Krishan,Saran, Mukesh,Mathur, Manas,Swami, Ajit K.,Chaudhary, Sandeep
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- Regiocontrolled direct C4 and C2-methyl thiolation of indoles under rhodium-catalyzed mild conditions
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A straightforward Rh(iii)-catalyzed general strategy was developed for the site-selective remote C4 (sp2) and C2 (sp3)-methyl thiolation of an indole core, keeping the oxime directing group at the C3 position. The transformation was accomplished under mild conditions with a wide scope and functional group tolerance. The directing group can easily be removed after operation. Methyl substitution at the C2 position of the indole core led to C2 (sp3)-methyl thiolation.
- Maity, Saurabh,Karmakar, Ujjwal,Samanta, Rajarshi
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supporting information
p. 12197 - 12200
(2017/11/16)
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- Br?nsted acidic ionic liquid-promoted direct C3-acylation of: N -unsubstituted indoles with acid anhydrides under microwave irradiation
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A green and efficient pathway for the synthesis of 3-acylindoles using a Br?nsted acidic ionic liquid as a catalyst has been developed for the first time. The C3-acylation of N-unsubstituted indoles with acid anhydrides affords the desired products in good to excellent yields with high regioselectivity under microwave irradiation. Moreover, the Br?nsted acidic ionic liquid can be recycled up to four times without significant loss of catalytic activity.
- Tran, Phuong Hoang,Duy Nguyen, Anh-Thanh,Nguyen, Hai Truong,Le, Thach Ngoc
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p. 54399 - 54406
(2017/12/12)
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- Chemical exploration of 4-(4-fluorobenzyl)piperidine fragment for the development of new tyrosinase inhibitors
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Tyrosinase is involved in the production of melanin through the hydroxylation of monophenols to o-diphenols. The role of this enzyme was extensively studied in order to identify new therapeutics preventing skin pigmentation and melanoma. In this work we initially identified the 3-(4-benzylpiperidin-1-yl)-1-(1H-indol-3-yl)propan-1-one (1a) as promising mushroom tyrosinase inhibitor (IC50= 252 μM). Then, several chemical modifications were performed and new analogues related to compound 1a were synthesized. Biochemical assays demonstrated that several obtained compounds proved to be effective inhibitors showing IC50values lower both than “lead compound” 1a and reference inhibitor kojic acid, as a well-known tyrosinase inhibitor. The inhibition kinetics analyzed by Lineweaver–Burk plots revealed that compounds 2 a-c and 10b act as non-competitive inhibitors while the most active inhibitor 2d (IC50= 7.56 μM) is a mixed-type inhibitor. Furthermore, experimental and computational structural studies were performed in order to clarify the binding mode of the derivative 2d.
- Ferro, Stefania,De Luca, Laura,Germanò, Maria Paola,Buemi, Maria Rosa,Ielo, Laura,Certo, Giovanna,Kanteev, Margarita,Fishman, Ayelet,Rapisarda, Antonio,Gitto, Rosaria
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p. 992 - 1001
(2016/11/11)
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- A simple, effective, green method for the regioselective 3-acylation of unprotected indoles
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A fast and green method is developed for regioselective acylation of indoles in the 3-position without the need for protection of the NH position. The method is based on Friedel-Crafts acylation using acid anhydrides. The method has been optimized, and Y(OTf)3 in catalytic amounts is found to be the best catalyst together with the commercially available ionic liquid [BMI]BF4 (1-butyl-3-methylimidazolium tetrafluoro-borate) as solvent. The reaction is completed in a very short time using monomode microwave irradiation. The catalyst can be reused up to four times without significant loss of activity. A range of substituted indoles are investigated as substrates, and thirteen new compounds have been synthesized.
- Tran, Phuong Hoang,Tran, Hai Ngoc,Hansen, Poul Erik,Do, Mai Hoang Ngoc,Le, Thach Ngoc
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p. 19605 - 19619
(2015/11/27)
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- Acid-catalyzed acylation reaction via C-C bond cleavage: A facile and mechanistically defined approach to synthesize 3-acylindoles
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A facile acid-catalyzed acylation of indoles with 1,3-dione as an eco-friendly acylating agent was developed. This protocol combines C-C bond cleavage and heterocyclic C-H bond functionalization to form new C-C bonds. Based on the detailed mechanistic studies, a credible mechanistic pathway was proposed. This journal is
- Xing, Qi,Li, Pan,Lv, Hui,Lang, Rui,Xia, Chungu,Li, Fuwei
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supporting information
p. 12181 - 12184
(2014/12/11)
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- A new potential approach to block HIV-1 replication via protein-protein interaction and strand-transfer inhibition
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Therapeutic treatment of AIDS is recently characterized by a crescent effort towards the identification of multiple ligands able to target different steps of HIV-1 life cycle. Taking into consideration our previously obtained SAR information and combining some important chemical structural features we report herein the synthesis of novel benzyl-indole derivatives as anti-HIV agents. Through this work we identified new dual target small molecules able to inhibit both IN-LEDGF/p75 interaction and the IN strand-transfer step considered as two crucial phases of viral life cycle.
- Ferro, Stefania,De Luca, Laura,Lo Surdo, Giuseppa,Morreale, Francesca,Christ, Frauke,Debyser, Zeger,Gitto, Rosaria,Chimirri, Alba
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p. 2269 - 2279
(2014/04/17)
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- Synthesis of 3-acylindoles by palladium-catalyzed acylation of free (N-H) indoles with nitriles
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An efficient palladium-catalyzed synthesis of 3-acylindoles using free (N-H) indoles and nitriles has been developed. The acylation reaction proceeded well under the Pd(OAc)2/2,2′-bipyridine system and with d-(+)-camphorsulfonic acid as the additive. A possible mechanism involving carbopalladation of nitriles and subsequent hydrolysis of ketimines is proposed.
- Jiang, Tao-Shan,Wang, Guan-Wu
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supporting information
p. 788 - 791
(2013/03/29)
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- Novel and simple methodology for the synthesis of 3-acetylindoles and their N-alkyl derivatives using TBAB as phase transfer catalyst
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Using 5% aq. NaOH, a simple method for the transformation of 3-cyanoacetylindoles 2(a-e) into 3-acetylindoles 3 (a-e), in good yields, is reported. Tetrabutylammoniumbromide (TBAB) is found to be an efficient phase transfer catalyst for the synthesis of N-alkyl derivatives 5(a-t) of 3-acetylindoles 3(a-e) giving products in excellent yields. 2 (a-e) were themselves obtained from simple indoles 1 (a-e) by reaction with cyano acetic acid in the presence of propionic anhydride at 100 °C for 5-10 min. Partial hydrolysis of 2 (a-e) under hot acidic conditions yielded the corresponding carboxamides α-(3-indolecarboxoyl)acetamides 4(a-e). Which could be readily transformed into the respective 3(a-e) by refluxing with 5% aq. NaOH for 2-2.5 h.
- Venkatanarayana,Dubey, Pramod K.
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experimental part
p. 656 - 662
(2012/06/01)
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- A refined pharmacophore model for HIV-1 integrase inhibitors: Optimization of potency in the 1H-benzylindole series
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We report herein the development of a new three-dimensional pharmacophore model for HIV-1 integrase inhibitors which led to the discovery of some 4-[1-(4-fluorobenzyl)-1H-indol-3-yl]-2-hydroxy-4-oxobut-2-enoic acids that are able to specifically inhibit the strand transfer step of integration at nanomolar concentration. The synthesis of the new designed molecules is also described.
- De Luca, Laura,Barreca, Maria Letizia,Ferro, Stefania,Iraci, Nunzio,Michiels, Martine,Christ, Frauke,Debyser, Zeger,Witvrouw, Myriam,Chimirri, Alba
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p. 2891 - 2895
(2008/12/21)
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- New 4-[(1-benzyl-1H-indol-3-yl)carbonyl]-3-hydroxyfuran-2(5H)-ones, β-diketo acid analogs as HIV-1 integrase inhibitors
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In addition to our recent report on a series of rationally designed benzylindolyldiketo acids acting as potent HIV-1 integrase strand transfer inhibitors, we disclose the results obtained with novel compounds chemically modified on the diketo acid moiety in order to investigate its influence on the biological activity and cytotoxicity. The activity of designed and synthesized 4-[(1-benzyl-1H-indol-3-yl)carbonyl]-3-hydroxyfuran-2(5H)-one derivatives lies in the micromolar range with regard to HIV IN enzymatic activity. The microwave-assisted synthesis was employed in some steps of the chemical procedures.
- Ferro, Stefania,Barreca, Maria Letizia,De Luca, Laura,Rao, Angela,Monforte, Anna Maria,Debyser, Zeger,Witvrouw, Myriam,Chimirri, Alba
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p. 292 - 298
(2008/02/10)
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- Pharmacophore-based design of HIV-1 integrase strand-transfer inhibitors
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Using a training set of diketo-like acid HIV-1 integrase (IN) strand-transfer inhibitors, a 3D pharmacophore model was derived having quantitative predictive ability in terms of activity. The best statistical hypothesis consisted of four features (one hydrophobic aromatic region, two hydrogen-bond acceptors, and one hydrogen-bond donor) with r of 0.96. The resulting pharmacophore model guided the rational design of benzylindoles as new potent IN inhibitors, whose microwave-assisted synthesis and biological evaluation are reported.
- Barreca, Maria Letizia,Ferro, Stefania,Rao, Angela,De Luca, Laura,Zappalà, Maria,Monforte, Anna-Maria,Debyser, Zeger,Witvrouw, Myriam,Chimirri, Alba
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p. 7084 - 7088
(2007/10/03)
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- 1-HETEROCYCLYL-1,5-DIHYDRO-PYRIDO[3,2-B]INDOL-2-ONES
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1-heterocyclyl-1,5-dihydro-pyrido[3,2-b]indo l-2-ones of formula (I): the N-oxides, salts, stereoisomeric forms, racemic mixtures, prodrugs, esters and metabolites thereo f, wherein n is 1, 2 or 3; R1 is hydrogen, cyano, halo, substituted carbonyl, methanimidamidyl, N-hydroxy- methanimidamidyl, mono- or di(C1-4alkyl)methanimidamidyl, Het1 or Het2; X is NR2, O, S, SO, SO2; R2 is hydrogen, C1-10alkyl, C2-10alkenyl, C3-7cycloalkyl, which are optionally substituted; R2 is aryl subst ituted with -COOR4 ; or R2 is: (b-1); (b-2); -CpH2p-CH(OR14)-CqH2q-R15 (b-3); -CH2-CH2-(O-CH2 -CH2)m-OR14 (b-4); -CH2-CH2-(O-CH2-CH2)m-NR5aR5b (b-5); -a1=a2-a3=a4- is -CH=CH-CH=CH-; -N=CH-CH=CH-; -CH=N-CH=CH-; -CH=CH-N=CH-; -CH=CH-CH=N-; wherein hydrogen atoms in (c-1) - (c-5) may be replaced by certain radicals; R3 is a monocyclic or bicyclic aromatic heterocyclic ring system that can be substituted.
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Page/Page column 77-78
(2008/06/13)
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- 6,7,8,9-SUBSTITUTED 1-PHENYL-1,5-DIHYDRO-PYRIDO[3,2-B]INDOL-2-ONES USEFUL AS ANTI-INFECTIVE PHARMACEUTICAL AGENTS
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This invention concerns the compounds (I); the N-oxides, salts, stereoisomeric forms, racemic mixtures, prodrugs, esters and metabolites thereof, wherein X is NR2, O, S, SO, SO2; R1 is hydrogen, cyano, halo, substituted carbonyl, methanimidamidyl, N-hydroxy-methanimidamidyl, mono- or di(C1-4alkyl)methanimidamidyl, Het1 or Het2; n is 1, 2 or 3; R2 is hydrogen, aryl substituted with a radical -COOR4; or R2 is substituted C1-10alkyl,C2-10alkenyl or C3-7cycloalkyl; or R2 is a radical of formula: (b-1); (b-2); -CpH2p-CH(OR14)-CqH2q-R15 (b-3); -CH2-CH2-(O-CH2-CH2)m-OR14 (b-4); -CH2-CH2-(O-CH2-CH2)m-NR5aR5b (b-5); -a1=a2-a3=a4- is -CH=CH-CH=CH- ; -N=CH-CH=CH- ;-CH=N-CH=CH- ; -CH=CH- N=CH- ; -CH=CH-CH=N- (c-5); wherein one of the hydrogen atoms in (c-1) - (c-5) is replaced by particular radicals; R3 is nitro, cyano, amino, halo, hydroxy, C1-4alkyloxy, hydroxycarbonyl, substituted carbonyl, methanimidamidyl, mono- or di(C1-4alkyl)methanimidamidyl, N-hydroxy- methanimidamidyl or Het1.
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Page/Page column 75-76
(2008/06/13)
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- Regeneration of carbonyl compounds from oximes using BTBAD under microwave irradiation
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Bis-tetrabutylammonium dichromate (BTBAD) has been found to be an efficient and new reagent for the conversion of oximes to the corresponding carbonyl compounds. The reaction was performed under microwave irradiation and gave excellent yields. It also facilitates the de-protection of acetals and ketals.
- Murugan,Reddy
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p. 1038 - 1039
(2007/10/03)
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- A general method for acylation of indoles at the 3-position with acyl chlorides in the presence of dialkylaluminum chloride.
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[reaction--see text] Indoles are selectively acylated at the 3-position in high yields on treatment with a wide variety of acyl chlorides in CH(2)Cl(2) in the presence of diethylaluminum chloride or dimethylaluminum chloride. The reaction proceeds under mild conditions and is applicable to indoles bearing various functional groups without NH protection.
- Okauchi,Itonaga,Minami,Owa,Kitoh,Yoshino
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p. 1485 - 1487
(2007/10/03)
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- Synthesis of 3-Substituted Indoles by a Palladium-Assisted Reaction
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In the presence of palladium(II) chloride, 2-bromoanilines readily react with the methyl vinyl ketone and the ethyl acrylate to produce vinylogous arylamino ketones and esters.A palladium(0)-assisted cyclization of the arylamino ketones and the esters leads to a formation of 3-substituted indoles.
- Kasahara, Akira,Izumi, Taeko,Murakami, Satoshi,Yanai, Hiroshi,Takatori, Masayuki
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p. 927 - 928
(2007/10/02)
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- A Convenient Synthesis of 3-Acylindoles via Friedel-Crafts Acylation of 1-(Phenylsulfonyl)indole. A New Route to Pyridocarbazole-5,11-quinones and Ellipticine
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A Friedel-Crafts acylation of 1-(phenylsulfonyl)indoles (1) with carboxylic acid anhydrides and acid chlorides in the presence of aluminum chloride gives 3-acyl-1-(phenylsulfonyl)indoles (2) in 81-99percent yields.Base hydrolysis converts 2 to 3-acylindoles (3) in 79-96percent yields.The reaction of 1-(phenylsulfonyl)indole (1a) with oxalyl chloride gives acid chloride 2h, which is converted to 3-cyanoindole (7) in three steps (75percent yield).Although a similar Friedel-Crafts alkylation of 1 was unsuccessful, in some cases the 3-acyl-1-(phenylsulfonyl)indoles 2a,e,f could be reduced to 3-alkyl-1-(phenylsulfonyl)indoles 8a,b,c in nearly quantitative yield with sodium borohydride in trifluoroacetic acid.The acid chloride derived from keto acid 9 did not cyclize to the desired pyridocarbazole-5,11-quinone 24 but rather to chloro keto lactam 10.However, acylation of 1a with acid chloride 22 followed by strong-base-mediated cyclization gives 24.Since quinone 24 has been previously converted to the alkaloid ellipticine 26, this route to 24 represents a new synthesis of ellipticine.Related synthetic schemes give rise to quinones 16 and 20.
- Ketcha, Daniel M.,Gribble, Gordon W.
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p. 5451 - 5457
(2007/10/02)
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