- Photoredox-Catalyzed Generation of Acetonyl Radical in Flow: Theoretical Investigation and Synthetic Applications
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A hydrogen atom transfer (HAT) step from acetone allowed the smooth generation of acetonyl radical that was then exploited as synthon in the mild formation of C-C bonds under flow conditions. The process was promoted by aryl radicals photocatalytically generated via single-electron transfer (SET) reduction of arenediazonium salts. The mechanism has been investigated by a combined experimental and computational approach and further supported by deuterium labeling experiments.
- Anselmo, Manuel,Basso, Andrea,Protti, Stefano,Ravelli, Davide
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- Study on the interaction of 1,5-diaryl pyrrole derivatives with αglucosidase; synthesis, molecular docking, and kinetic study
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Background: The delaying of absorption of glucose is one of the principal therapeutic approaches of type 2 diabetes. α-glucosidase inhibitors compete with the α-glucosidase enzyme activity, which helps to reduce the conversion of carbohydrates into glucose and thereby control the postprandial hyperglycemia incidence. Objective: The aim of this study was to synthesize a series of novel 1,5-diphenyl pyrrole derivatives and evaluate their in vitro α-glucosidase inhibitory activities. Methods: Compounds were synthesized through a multistep reaction and were evaluated for αglucosidase inhibitory activities. Molecular docking and kinetic studies were carried out to predict the mode of binding and mechanism of inhibition for the most active compounds, 5g and 5b, against α-glucosidase. Results: Synthesized compounds showed good in vitro α-glucosidase inhibitory activity with IC50 values in the range of (117.5 ± 3.8 to 426.0 ± 10.2 μM) as compared to acarbose, the standard drug, (750 ± 8.7 μM). Compound 5g (117.5 ± 3.8 μM) ascertained as the most potent inhibitor of α-glucosidase in a competitive mode. The binding energies of compounds 5g and 5b (119.0 ± 7.5 μM), as observed from the best docking conformations, indicate that they have a lower free binding energy (-3.26 kcal/mol and-3.0 kcal/mol, respectively) than acarbose (2.47 kcal/mol). Conclusion: The results of our study revealed that the synthesized compounds are a potential candidate for α-glucosidase inhibitors for the management of postprandial hyperglycemia for further investigation.
- Tafesse, Tadesse Bekele,Moghadam, Ebrahim Saeedian,Bule, Mohammed Hussen,Faramarzi, Mohammad Ali,Abdollahi, Mohammad,Amini, Mohsen
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p. 545 - 553
(2021/03/26)
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- Enantioselective Synthesis of Nitrogen-Nitrogen Biaryl Atropisomers via Copper-Catalyzed Friedel-Crafts Alkylation Reaction
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Nitrogen-nitrogen bonds containing motifs are ubiquitous in natural products and bioactive compounds. However, the atropisomerism arising from a restricted rotation around an N-N bond is largely overlooked. Here, we describe a method to access the first enantioselective synthesis of N-N biaryl atropisomers via a Cu-bisoxazoline-catalyzed Friedel-Crafts alkylation reaction. A wide range of axially chiral N-N bisazaheterocycle compounds were efficiently prepared in high yields with excellent enantioselectivities via desymmetrization and kinetic resolution. Heating experiments showed that the axially chiral bisazaheterocycle products have high rotational barriers.
- Guo, Chang-Qiu,Liu, Ren-Rong,Lu, Chuan-Jun,Wang, Xiao-Mei,Xu, Qi,Zhang, De-Bing,Zhang, Peng
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supporting information
p. 15005 - 15010
(2021/09/30)
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- Nickel-Mediated Photoreductive Cross Coupling of Carboxylic Acid Derivatives for Ketone Synthesis**
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A simple visible light photochemical, nickel-catalyzed synthesis of ketones from carboxylic acid-derived precursors is presented. Hantzsch ester (HE) functions as a cheap, green and strong photoreductant to facilitate radical generation and also engages in the Ni-catalytic cycle to restore the reactive species. With this dual role, HE allows for the coupling of a large variety of radicals (1°,2°, benzylic, α-oxy & α-amino) with aroyl and alkanoyl moieties, a new feature in reactions of this type. With both precursors deriving from abundant carboxylic acids, this protocol is a welcome addition to the organic chemistry toolbox. The reaction proceeds under mild conditions without the need for toxic metal reagents or bases and shows a wide scope, including pharmaceuticals and complex molecular architectures.
- Brauer, Jan,Quraishi, Elisabeth,Kammer, Lisa Marie,Opatz, Till
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p. 18168 - 18174
(2021/11/30)
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- Oxidative Cleavage of Alkenes by O2with a Non-Heme Manganese Catalyst
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The oxidative cleavage of C═C double bonds with molecular oxygen to produce carbonyl compounds is an important transformation in chemical and pharmaceutical synthesis. In nature, enzymes containing the first-row transition metals, particularly heme and non-heme iron-dependent enzymes, readily activate O2 and oxidatively cleave C═C bonds with exquisite precision under ambient conditions. The reaction remains challenging for synthetic chemists, however. There are only a small number of known synthetic metal catalysts that allow for the oxidative cleavage of alkenes at an atmospheric pressure of O2, with very few known to catalyze the cleavage of nonactivated alkenes. In this work, we describe a light-driven, Mn-catalyzed protocol for the selective oxidation of alkenes to carbonyls under 1 atm of O2. For the first time, aromatic as well as various nonactivated aliphatic alkenes could be oxidized to afford ketones and aldehydes under clean, mild conditions with a first row, biorelevant metal catalyst. Moreover, the protocol shows a very good functional group tolerance. Mechanistic investigation suggests that Mn-oxo species, including an asymmetric, mixed-valent bis(μ-oxo)-Mn(III,IV) complex, are involved in the oxidation, and the solvent methanol participates in O2 activation that leads to the formation of the oxo species.
- Bennett, Elliot L.,Brookfield, Adam,Guan, Renpeng,Huang, Zhiliang,Mcinnes, Eric J. L.,Robertson, Craig M.,Shanmugam, Muralidharan,Xiao, Jianliang
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supporting information
p. 10005 - 10013
(2021/07/19)
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- Alkyne Trifunctionalization via Divergent Gold Catalysis: Combining π-Acid Activation, Vinyl-Gold Addition, and Redox Catalysis
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Here we report the first example of alkyne trifunctionalization through simultaneous construction of C-C, C-O, and C-N bonds via gold catalysis. With the assistance of a γ-keto directing group, sequential gold-catalyzed alkyne hydration, vinyl-gold nucleophilic addition, and gold(III) reductive elimination were achieved in one pot. Diazonium salts were identified as both electrophiles (N source) and oxidants (C source). Vinyl-gold(III) intermediates were revealed as effective nucleophiles toward diazonium, facilitating nucleophilic addition and reductive elimination with high efficiency. The rather comprehensive reaction sequence was achieved with excellent yields (up to 95%) and broad scope (>50 examples) under mild conditions (room temperature or 40 °C).
- Yuan, Teng,Tang, Qi,Shan, Chuan,Ye, Xiaohan,Wang, Jin,Zhao, Pengyi,Wojtas, Lukasz,Hadler, Nicholas,Chen, Hao,Shi, Xiaodong
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supporting information
p. 4074 - 4082
(2021/04/06)
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- Dibromo-BODIPY as an Organic Photocatalyst for Radical-Ionic Sequences
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A new dibrominated 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) is reported as a new metal-free photocatalyst. This BODIPY showed similar optoelectronic, electrochemical, and performance properties to those of Ru(bpy)3Cl2, one of the most common photocatalysts in a known radical-ionic transformation, such as the formation of 1,4-dicarbonyl compounds. Moreover, additional sequences in which the generated oxonium ion is trapped by an internal nucleophile were developed using this BODIPY photocatalyst. These new sequences allowed the straightforward preparation of ?3-alkoxylactones, monoprotected 1,4-ketoaldehydes, and dihydrofurans. This new catalyst, the methodology, and the forged functional groups could be important tools in organic synthesis.
- Garciá-Santos, William H.,Ordó?ez-Hernández, Javier,Farfán-Paredes, Mónica,Castro-Cruz, Hiram M.,Maciás-Ruvalcaba, Norma A.,Farfán, Norberto,Cordero-Vargas, Alejandro
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p. 16315 - 16326
(2021/11/18)
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- Synthesis and biological evaluation of 2-(2-methyl-1H-pyrrol-3-yl)-2-oxo-N-(pyridine-3-yl) acetamide derivatives: in vitro α-glucosidase inhibition, and kinetic and molecular docking study
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One of the therapeutic approaches in the management of type 2 diabetes is delaying the glucose absorption through α-glucosidase enzyme inhibition, which can reduce the occurrence of postprandial hyperglycemia. Based on this thought, a series of novel chloro-substituted 2-(2-methyl-1-phenyl-1H-pyrrol-3-yl)-2-oxo-N-(pyridin-3-yl) acetamide derivatives 5a–i were synthesized and their α-glucosidase inhibitory activities were evaluated. All the synthesized compounds have shown moderate to excellent in vitro α-glucosidase inhibitory activity with IC50 values in the range of 111–673?μM) as compared to acarbose, the standard drug (750 ± 9?μM). Compound 5e (111 ± 12?μM), among the series, was the most potent inhibitor of α-glucosidase in a competitive mode of action based on the kinetic study. The molecular docking study of compounds 5e and 5a revealed that they have a lower free binding energy (? 4.27?kcal/mol and ? 3.17?kcal/mol, respectively) than acarbose (? 2.47?kcal/mol), which indicates that the target compound binds more easily to the enzyme than acarbose does. The outcomes from the molecular docking studies supported the results obtained from the in vitro assay. In conclusion, the overall results of our study reveal that the synthesized compounds could be a potential candidate in the search for novel α-glucosidase inhibitors to manage postprandial hyperglycemia incidence.
- Tafesse, Tadesse Bekele,Moghadam, Ebrahim Saeedian,Bule, Mohammed Hussen,Abadian, Neda,Abdollahi, Mohammad,Faramarzi, Mohammad Ali,Amini, Mohsen
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p. 1583 - 1596
(2019/12/11)
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- Design, synthesis and in-vitro anti-cancer evaluation of novel derivatives of 2-(2-methyl-1,5-diaryl-1h-pyrrol-3-yl)-2-oxo-n-(pyridin-3-yl)acetamide
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Objective: Several anti-tubulin agents were introduced for the cancer treatment so far. Despite successes in the treatment of cancer, these agents cause toxic side effects, including peripheral neuropathy. Comparing anti-tubulin agents, indibulin seemed to cause minimal peripheral neuropathy, but its poor aqueous solubility and other potential clinical problems have led to its remaining in a preclinical stage. Methods: Herein, indibulin analogues were synthesized and evaluated for their in vitro anti-cancer activity using MTT assay (on the MCF-7, T47-D, MDA-MB231 and NIH-3T3 cell lines), annexin V/PI staining assay, cell cycle analysis, anti-tubulin assay and caspase 3/7 activation assay. Results: One of the compounds, 4a, showed good anti-proliferative activity against MCF-7 cells (IC50: 7.5 μM) and low toxicity on a normal cell line (IC50 > 100μM). All of the tested compounds showed lower cytotoxicity on normal cell line in comparison to reference compound, indibulin. In the annexin V/PI staining assay, induction of apoptosis in the MCF-7 cell line was observed. Cell cycle analysis illustrated an increasing proportion of cells in the sub-G-1 phase, consistent with an increasing proportion of apoptotic cells. No increase in G2/M cells was observed, consistent with the absence of anti-tubulin activity. A caspase 3/7 assay protocol showed that apoptosis induction by more potent compounds was due to activation of caspase 3. Conclusion: newly synthesized compounds exerted acceptable anticancer activity and further investigation of current scaffold would be beneficial.
- Alipour, Mohsen,Amini, Mohsen,Hamel, Ernest,Hosseinkhani, Saman,Moghadam, Ebrahim Saeedian,Ostad, Seyednasser,Saravani, Farhad,Shahsavari, Zahra
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p. 340 - 349
(2020/04/17)
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- A fluorescent target-guided Paal-Knorr reaction
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It has become increasingly apparent that high-diversity chemical reactions play a significant role in the discovery of bioactive small molecules. Here, we describe an expanse of this paradigm, combining a ‘target-guided synthesis’ concept with Paal-Knorr chemistry applied to the preparation of fluorescent ligands for human prostaglandin-endoperoxide synthase (COX-2).
- Kornienko, Alexander,La Clair, James J.,Maslivetc, Vladimir,Wagh, Sachin B.
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p. 37035 - 37039
(2020/10/19)
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- Synergistic Activation of Amides and Hydrocarbons for Direct C(sp3)–H Acylation Enabled by Metallaphotoredox Catalysis
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The utilizations of omnipresent, thermodynamically stable amides and aliphatic C(sp3)?H bonds for various functionalizations are ongoing challenges in catalysis. In particular, the direct coupling between the two functional groups has not been realized. Here, we report the synergistic activation of the two challenging bonds, the amide C?N and unactivated aliphatic C(sp3)?H, via metallaphotoredox catalysis to directly acylate aliphatic C?H bonds utilizing amides as stable and readily accessible acyl surrogates. N-acylsuccinimides served as efficient acyl reagents for the streamlined synthesis of synthetically useful ketones from simple C(sp3)?H substrates. Detailed mechanistic investigations using both computational and experimental mechanistic studies were performed to construct a detailed and complete catalytic cycle. The origin of the superior reactivity of the N-acylsuccinimides over other more reactive acyl sources such as acyl chlorides was found to be an uncommon reaction pathway which commences with C?H activation prior to oxidative addition of the acyl substrate.
- Baik, Mu-Hyun,Choi, Seulhui,Hong, Soon Hyeok,Lee, Geun Seok,Won, Joonghee
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p. 16933 - 16942
(2020/08/03)
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- Regioselective Crossed Aldol Reactions under Mild Conditions via Synergistic Gold-Iron Catalysis
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A synergistic gold-iron (Au-Fe) catalytic system was developed for sequential alkyne hydration and vinyl Au addition to aldehydes or ketones. Fe(acac)3 was identified as an essential co-catalyst in preventing vinyl Au protodeauration and facilitating nucleophilic additions. Effective C–C bond formation was achieved under mild conditions (room temperature) with excellent regioselectivity and high efficiency (1% [Au], up to 95% yields). The intramolecular reaction was also achieved, giving successful macrocyclization (16–31 ring sizes) with excellent yields (up to 90%, gram scale) without extended dilution (0.2 M), which highlights the great potential of this new crossed aldol strategy in challenging target molecule synthesis. Effective construction of the C–C bond is one of the most important tasks in organic synthesis. Whereas aldol condensation is a classic C–C bond-forming transformation, it requires other chemical promoters, such as strong base and reactive acidic catalysts. As a result, the overall transformation is limited in terms of ideal atom economy and environmentally friendly operation. With the discovery of a gold-iron (Au-Fe) synergistic catalysis system, here we describe a new approach to facilitating alkyne hydration and sequential vinyl Au addition to carbonyls. This approach gives the C–C bond-forming products in excellent yields, wide substrate scope, and great functional-group compatibility under mild conditions. This protocol can also be applied to macrocyclization without extended dilution. This C–C bond-forming strategy could facilitate challenging molecule synthesis in chemical, biological, and medicinal research. We report a synergistic gold-iron (Au-Fe) catalytic system to access vinyl Au reactivity by avoiding frequently occurring protodeauration. Fe(acac)3 was identified as an essential co-catalyst, facilitating vinyl Au addition to aldehydes. A broad substrate scope was obtained under mild conditions (room temperature) with excellent regioselectivity and high efficiency (1% [Au], up to 95% yields). This protocol offers a practical solution for achieving macrocyclization (16–31 ring sizes, up to 90%, gram scale) without extended dilution, highlighting the synthetic utility in complex molecular synthesis.
- Chen, Hao,Jean, Jonathan,Shan, Chuan,Shi, Xiaodong,Teng, Shun,Wang, Jin,Wojtas, Lukasz,Ye, Xiaohan,Yi, Yaping,Yuan, Teng,Zhao, Pengyi
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supporting information
p. 1420 - 1431
(2020/06/19)
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- Electrochemistry Broadens the Scope of Flavin Photocatalysis: Photoelectrocatalytic Oxidation of Unactivated Alcohols
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Riboflavin-derived photocatalysts have been extensively studied in the context of alcohol oxidation. However, to date, the scope of this catalytic methodology has been limited to benzyl alcohols. In this work, mechanistic understanding of flavin-catalyzed oxidation reactions, in either the absence or presence of thiourea as a cocatalyst, was obtained. The mechanistic insights enabled development of an electrochemically driven photochemical oxidation of primary and secondary aliphatic alcohols using a pair of flavin and dialkylthiourea catalysts. Electrochemistry makes it possible to avoid using O2 and an oxidant and generating H2O2 as a byproduct, both of which oxidatively degrade thiourea under the reaction conditions. This modification unlocks a new mechanistic pathway in which the oxidation of unactivated alcohols is achieved by thiyl radical mediated hydrogen-atom abstraction.
- Zhang, Wen,Carpenter, Keith L.,Lin, Song
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supporting information
p. 409 - 417
(2019/11/25)
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- Catalytic Transfer Hydrogenation Using Biomass as Hydrogen Source
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We developed an operationally simple method for the direct use of biomass-derived chemical entities in a fundamentally important process, such as hydrogenation. Various carbohydrates, starch, and lignin were used for stereoselective hydrogenation. Employing a transition metal catalyst and a novel catalytic system, the reduction of alkynes, alkenes, and carbonyl groups with high yields was demonstrated. The regioselective hydrogenation to access different stereoisomers was established by simple variations in the reaction conditions. This work is based on an unprecedented catalytic system and represents a straightforward application of biomass as a reducing reagent in chemical reactions.
- Antonchick, Andrey P.,Manna, Srimanta
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p. 3094 - 3098
(2018/09/14)
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- Catalytic Wacker-type Oxidations Using Visible Light Photoredox Catalysis
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A combined palladium/photoredox catalytic system for the efficient oxidation of terminal olefins to the corresponding methyl ketones is presented. The interplay of air, water, and light leads to a protocol in which the stoichiometric oxidants required for oxidative palladium catalysis are substituted with catalytic, single-electron transfer processes. Detailed mechanistic investigations revealed the role of the key components, in situ generated species, and catalysts. A broad range of substrates was examined in homogeneous as well as heterogeneous photoredox protocols, delivering the desired products in good yields.
- Ho, Yee Ann,Paffenholz, Eva,Kim, Hyun Jin,Orgis, Benjamin,Rueping, Magnus,Fabry, David C.
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p. 1889 - 1892
(2019/03/17)
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- Copper-Catalyzed Decarboxylative Oxyalkylation of Alkynyl Carboxylic Acids: Synthesis of ?-Diketones and ?-Ketonitriles
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A novel copper-catalyzed decarboxylative oxyalkylation of alkynyl carboxylic acids with ketones and alkylnitriles via direct C(sp3)-H bond functionalization to construct new C-C bonds and C-O double bonds was developed. This transformation is featured by wide functional group compatibility and the use of readily available reagents, thus affording a general approach to ?-diketones and ?-ketonitriles. A possible mechanism is proposed.
- Li, Yi,Shang, Jia-Qi,Wang, Xiang-Xiang,Xia, Wen-Jin,Yang, Tao,Xin, Yangchun,Li, Ya-Min
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supporting information
p. 2227 - 2230
(2019/03/26)
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- Synthesis and anti-breast cancer activity of novel indibulin related diarylpyrrole derivatives
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Background: During recent years, a number of anti-tubulin agents were introduced for treatment of diverse types of cancer. Despite their potential in the treatment of cancer, drug resistance and adverse toxicity, such as peripheral neuropathy, are some of the negative effects of anti-tubulin agents. Among anti-tubulin agents, indibulin was found to cause minimal peripheral neuropathy. Thus far, however, indibulin has not entered clinical usage, caused in part by its poor aqueous solubility and other developmental problems in preclinical evaluation. Objectives: With respect to need for finding potent and safe anticancer agents, in our current research work, we synthesized several indibulin-related diarylpyrrole derivatives and investigated their anti-cancer activity. Methods: Cell cultur studies were perfomred using the MTT cell viability assay on the breast cancer cell lines MCF-7, T47-D, and MDA-MB231 and also NIH-3?T3 cells as representative of a normal cell line. The activity of some of the synthesized compounds for tubulin interaction was studied using colchicine binding and tubulin polymerization assays. The annexin V-FITC/PI method and flow cytometric analysis were used for studying apoptosis induction and cell cycle distribution. Results and conclusion: Two of the synthesized compounds, 4f and 4?g, showed high activity on the MDA-MB231 cell line (IC50?= 11.82 and 13.33?μM, (respectively) and low toxicity on the normal fibroblast cells (IC50?> 100?μM). All of the tested compounds were more potent on T47-D cancer cells and less toxic on NIH-3?T3 normal cells in comparison to reference compound, indibulin. The tubulin polymerization inhibition assay and [3H]colchicine binding assay showed that the main mechanism of cell death by the potent synthesized compounds was not related to an interaction with tubulin. In the annexin V/PI staining assay, the induction of apoptosis in the MCF-7 and MDA-MB231 cell lines was observed. Cell cycle analysis illustrated an increased percentage of sub-G-1 cells in the MDA-MB231 cell line as a further indication of cell death through induction of apoptosis. [Figure not available: see fulltext.].
- Saeedian Moghadam, Ebrahim,Hamel, Ernest,Shahsavari, Zahra,Amini, Mohsen
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p. 179 - 189
(2019/03/26)
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- Design, synthesis and anticancer evaluation of novel series of indibulin analogues
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Background: Cancer is an important cause of human death worldwide. During the last decades, many anticancer agents with anti-tubulin mechanism have been synthesized or extracted from nature and some of them also entered clinical use. Indibulin is one of the most potent tubulin polymerization inhibitors with minimal peripheral neuropathy, which is a big problem by some of the antimitotic agents such as taxanes and vinka alkaloids. With respect to this giant benefit, herein we decided to design and synthesize novel indibulin related compounds and investigate their anticancer activity against HT-29, Caco-2 and T47-D cancerous cell lines as well as NIH-T3T as normal cell line. Objective: The aim of this study was to synthesize new anti-cancer agents and evaluates their cytotoxic activity on diverse cancerous and normal cell lines. Method: Target compounds were synthesized in multistep reaction and cytotoxic activity was investigated by MTT cell viability assay. Results: Herein, nine novel target compounds were synthesized in moderate to good yield. Some of the compounds exerted good cytotoxic activity against cancerous cell lines. Annexin V/PI staining showed that compound 4g could induce apoptosis and necrosis in HT-29 cell line. Conclusion: It is valuable to do further investigation on compound 4g which showed the highest activity against HT-29 and Caco-2 (IC50 values are 6.9 and 7 μM respectively). Also, synthesis of new derivatives of current synthesized compounds is suggested.
- Amini, Mohsen,Hamedani, Morteza P.,Moghadam, Ebrahim S.,Ostad, Seyednasser,Saravani, Farhad,Tavajohi, Shohreh
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p. 231 - 239
(2019/07/12)
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- Benzothiazolines as radical transfer reagents: Hydroalkylation and hydroacylation of alkenes by radical generation under photoirradiation conditions
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Novel radical transfer reagents under photoirradiation conditions were developed by the use of benzothiazoline derivatives. These reagents enabled both hydroalkylation and hydroacylation of alkenes under neutral conditions at ambient temperature without a
- Uchikura, Tatsuhiro,Moriyama, Kaworuko,Toda, Mitsuhiro,Mouri, Toshiki,Ibá?ez, Ignacio,Akiyama, Takahiko
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p. 11171 - 11174
(2019/09/30)
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- Visible-Light Photocatalytic Preparation of 1,4-Ketoaldehydes and 1,4-Diketones from α-Bromoketones and Alkyl Enol Ethers
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A Ru2+-photocatalyzed, visible-light-mediated ATRA reaction for the straightforward preparation of 1,4-ketoaldehydes, 1,4-diketones, and 1,4-ketoesters, which are of difficult access by other means, is reported herein. This method employs readily accessible α-bromoketones and alkyl vinyl ethers as starting materials, allowing the construction of secondary, tertiary, and challenging quaternary centers. In addition, the synthetic usefulness of this method is illustrated by applying it to the construction of substituted pyrroles.
- García-Santos, William H.,Mateus-Ruiz, Jeferson B.,Cordero-Vargas, Alejandro
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supporting information
p. 4092 - 4096
(2019/06/17)
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- Nonclassical Mechanism in the Cyclodehydration of Diols Catalyzed by a Bifunctional Iridium Complex
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1,4- and 1,5-diols undergo cyclodehydration upon treatment with cationic N-heterocyclic carbene (NHC)–IrIII complexes to give tetrahydrofurans and tetrahydropyrans, respectively. The mechanism was investigated, and a metal-hydride-driven pathway was proposed for all substrates, except for very electron-rich ones. This contrasts with the well-established classical pathways that involve nucleophilic substitution.
- González Miera, Greco,Bermejo López, Aitor,Martínez-Castro, Elisa,Norrby, Per-Ola,Martín-Matute, Belén
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supporting information
p. 2631 - 2636
(2019/02/01)
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- Selective C(sp3)?H Aerobic Oxidation Enabled by Decatungstate Photocatalysis in Flow
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A mild and selective C(sp3)?H aerobic oxidation enabled by decatungstate photocatalysis has been developed. The reaction can be significantly improved in a microflow reactor enabling the safe use of oxygen and enhanced irradiation of the reaction mixture. Our method allows for the oxidation of both activated and unactivated C?H bonds (30 examples). The ability to selectively oxidize natural scaffolds, such as (?)-ambroxide, pregnenolone acetate, (+)-sclareolide, and artemisinin, exemplifies the utility of this new method.
- Laudadio, Gabriele,Govaerts, Sebastian,Wang, Ying,Ravelli, Davide,Koolman, Hannes F.,Fagnoni, Maurizio,Djuric, Stevan W.,No?l, Timothy
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supporting information
p. 4078 - 4082
(2018/03/21)
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- Design, synthesis and cytotoxicity evaluation of indibulin analogs
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Indibulin is one of the most potent tubulin polymerization inhibitors with minimal peripheral neuropathy. The design and synthesis of new indibulin analogs were carried out in order to investigate their anti-cancer activity. The target compounds 4a-i were synthesized in multistep reactions starting with the related indole derivatives. Compound 4f shows the highest cytotoxic activity on HT-29 and Caco-2 cell lines with the respective half maximal inhibitory concentration (IC50) values of 5.1 μm and 7.3 μm. In the case of the T47-D cell line, compound 4c exerts the best cytotoxic activity with an IC50 value of 11.5 μm. In the cell cycle analysis on HT-29 cells, compound 4f at 5.1 μm showed an increase in the percentage of cells in the sub-G1 phase. Altogether, nine target compounds were synthesized and characterized by infrared spectroscopy (IR), proton nuclear magnetic resonance (1H NMR), carbon-13 nuclear magnetic resonance (13C NMR), mass spectrometry (MS) and elemental analysis. Some of the compounds show good cytotoxic activity against cancerous cell lines.
- Saeedian Moghadam, Ebrahim,Saravani, Farhad,Ostad, Seyednasser,Tavajohi, Shohreh,Pirali Hamedani, Morteza,Amini, Mohsen
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p. 211 - 217
(2018/08/07)
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- Synthesis of Diketones, Ketoesters, and Tetraketones by Electrochemical Oxidative Decarboxylation of Malonic Acid Derivatives: Application to the Synthesis of cis-Jasmone
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Disubstituted malonic acid derivatives are smoothly converted into diketones and ketoesters in good to excellent yield (68% to 91%) under electrochemical conditions. The scope can be extended to transform trisubstituted bis-malonic acids into tetraketones in 77% to 86% yield. The new method was applied to the total synthesis of cis-jasmone.
- Ma, Xiaofeng,Du, Le,Luo, Xiya,Markó, István E.,Dewez, Damien F.,Lam, Kevin
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p. 12044 - 12055
(2019/03/01)
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- Synthesis of 2,5-Disubstituted Pyrrolidine Alkaloids via A One-Pot Cascade Using Transaminase and Reductive Aminase Biocatalysts
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A multi-enzymatic cascade process involving transaminases (TAs) and reductive aminases (RedAms) to produce enantiomerically pure 2,5-disubstituted pyrrolidine alkaloids from their respective 1,4-diketones is reported. Several TAs were screened and the best results for diketone monoamination were obtained with an R-selective TA from Mycobacterium chlorophenicum and with an S-selective TA from Bacillus megaterium. Pyrroline reduction was best performed by a reductive aminase from Ajellomyces dermatitidis (AdRedAm). Finally, a biocatalytic one-pot cascade was implemented using the aforementioned enzymes and a variety of 2-methyl-5-alkylpyrrolidines were produced with high (>99 %) conversion, diastereomeric and enantiomeric excess values.
- Costa, Bruna Z.,Galman, James L.,Slabu, Iustina,France, Scott P.,Marsaioli, Anita J.,Turner, Nicholas J.
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p. 4733 - 4738
(2018/09/25)
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- Synthesis of Diketones, Ketoesters, and Tetraketones by Electrochemical Oxidative Decarboxylation of Malonic Acid Derivatives: Application to the Synthesis of cis-Jasmone
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Disubstituted malonic acid derivatives are smoothly converted into diketones and ketoesters in good to excellent yield (68% to 91%) under electrochemical conditions. The scope can be extended to transform trisubstituted bis-malonic acids into tetraketones in 77% to 86% yield. The new method was applied to the total synthesis of cis-jasmone.
- Ma, Xiaofeng,Dewez, Damien F.,Du, Le,Luo, Xiya,Markó, István E.,Lam, Kevin
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- Detrifluoroacetylation Reaction of Trifluoromethyl-β-diketones: Facile Method for the Synthesis of Succinimide Derivatives and 1,4-Diketones
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Currently, a great deal of research efforts are focused on C–C bond activation for development of novel synthetic methodology. In this paper, a detrifluoroacetylation of trifluoromethyl-β-diketones is described, which allows for the synthesis of succinimides and 1,4-diketones through cascade Michael addition/retro-Claisen reaction and nucleophilic substitution/retro-Claisen reaction. The readily available trifluoromethyl-β-diketones, wide substrate scope, and mild conditions make this method very practical.
- Wang, Li-Hua,Zhao, Jing
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supporting information
p. 4345 - 4348
(2018/08/31)
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- Intramolecular Schmidt Reaction of Vinyl Azides with Cyclic Ketones
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Cyclic ketones tethered with a vinyl azide group undergo a Schmidt-hydrolysis sequence to give secondary lactams bearing a ketone side chain. Secondary lactams are obtained in a regioselective manner that is not possible in a conventional Schimdt reaction. In addition to the well-documented C-2 nucleophilicity, the N nucleophilicity of vinyl azide disclosed in this work opens a new direction for reaction invention involving vinyl azides.
- Chen, Peng,Sun, Chu-Han,Wang, Yu,Xue, Ying,Chen, Chen,Shen, Mei-Hua,Xu, Hua-Dong
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supporting information
p. 1643 - 1646
(2018/03/23)
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- One-pot synthesis of 2-methyl-1,5-diaromatic-1H-pyrroles from styrene, acetone and arylamines using TBHP, copper(II) trifluoromethanesulfonate and sulfamic acid
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The one-pot copper/manganese co-catalyzed heterocyclization of arylamine derivatives with styrene and acetone to produce a series of 2-methyl-1,5-diaromatic-1H-pyrroles was investigated. The described reaction combines 1,4-dicarbonyl synthesis and Paal-Knorr type condensation reactions.
- Xu, Congjun,Han, Yufei,Chen, Shaowei,Xu, Dengzhi,Zhang, Bingfu,Shan, Zhenliang,Du, Shimei,Xu, Liying,Gong, Ping
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p. 260 - 263
(2017/12/29)
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- NOVEL PROCESS FOR PREPARING SYNTHESIS INTERMEDIATES USING PRODUCTS OF NATURAL ORIGIN AND USE OF THE INTERMEDIATES OBTAINED
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Disclosed is a process for preparing a product of formula I: wherein the reaction is catalyzed both by thiamine or a thiamine salt and by ascorbic acid in a form which is free or salified or an organic acid salt of an alkaline metal, preferably sodium acetate, potassium tartrate, sodium succinate, or a reductone, preferably 2-hydroxypropanedial or 2,3-dihydroxycyclopent-2-ene-1-one in an organic solvent.
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-
Paragraph 0231
(2017/12/15)
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- Scalable, Electrochemical Oxidation of Unactivated C-H Bonds
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A practical electrochemical oxidation of unactivated C-H bonds is presented. This reaction utilizes a simple redox mediator, quinuclidine, with inexpensive carbon and nickel electrodes to selectively functionalize "deep-seated" methylene and methine moieties. The process exhibits a broad scope and good functional group compatibility. The scalability, as illustrated by a 50 g scale oxidation of sclareolide, bodes well for immediate and widespread adoption.
- Kawamata, Yu,Yan, Ming,Liu, Zhiqing,Bao, Deng-Hui,Chen, Jinshan,Starr, Jeremy T.,Baran, Phil S.
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supporting information
p. 7448 - 7451
(2017/06/13)
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- Synthesis of 1,4-Dicarbonyl Compounds from Silyl Enol Ethers and Bromocarbonyls, Catalyzed by an Organic Dye under Visible-Light Irradiation with Perfect Selectivity for the Halide Moiety over the Carbonyl Group
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We report the visible-light-induced radical coupling reaction of silyl enol ethers with α-bromocarbonyl compounds to give 1,4-dicarbonyls. The reaction was effectively accelerated using an inexpensive organic dye (eosin Y) as a photoredox catalyst. 1,4-Dicarbonyl compounds alone were afforded, without the generation of carbonyl adducts of the α-halocarbonyls, which are usually generated in the presence of fluoride anions or Lewis acids. A variety of silyl enol ethers, α-bromoketones, α-bromoesters, and α-bromoamides were applied to this system to produce the coupling compounds.
- Esumi, Naoto,Suzuki, Kensuke,Nishimoto, Yoshihiro,Yasuda, Makoto
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supporting information
p. 5704 - 5707
(2016/11/17)
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- Development of a Palladium-Catalyzed Carbonylative Coupling Strategy to 1,4-Diketones
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We report on a three-component palladium-catalyzed coupling strategy for accessing a wide range of 1,4-diketones, which represent important precursors to heterocycles. Our method relies on a carbonylative Heck reaction employing substituted allylic alcohols, aryl iodides, and carbon monoxide. The reaction conditions are mild and do not require high CO pressure, and a wide functional group tolerance is revealed, providing the desired 1,4-diketones in moderate to good yields. Furthermore, the methodology is adaptable to the selective installment of 13C-carbon isotopes at either one or both of the carbonyl positions.
- Yin, Hongfei,Nielsen, Dennis U.,Johansen, Mette K.,Lindhardt, Anders T.,Skrydstrup, Troels
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p. 2982 - 2987
(2016/07/06)
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- Copper/Manganese Cocatalyzed Oxidative Coupling of Vinylarenes with Ketones
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A novel copper/manganese cocatalyzed direct oxidative coupling of terminal vinylarenes with ketones via C(sp3)-H bond functionalization following C-C bond formation has been developed using tert-butyl hydroperoxide as the radical initiator. Various ketones underwent a free-radical addition of terminal vinylarenes to give the corresponding 1,4-dicarbonyl products with excellent regioselectivity and efficiency through one step. A possible reaction mechanism has been proposed.
- Lan, Xing-Wang,Wang, Nai-Xing,Zhang, Wei,Wen, Jia-Long,Bai, Cui-Bing,Xing, Yalan,Li, Yi-He
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supporting information
p. 4460 - 4463
(2015/09/28)
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- Copper-catalyzed aerobic C-C bond cleavage of lactols with N-hydroxy phthalimide for synthesis of lactones
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The transformation of cyclic hemiacetals (lactols) into lactones has been achieved by Cu-catalyzed aerobic C-C bond cleavage in the presence of N-hydroxy phthalimide (NHPI). The present process is composed of a multistep sequence including a) formation of exo-cyclic enol ethers by dehydration; b) addition of phthalimide N-oxyl radical to the enol ethers followed by trapping of the resulting C-radicals with molecular oxygen to form peroxy radicals; c) reductive generation of oxy radicals and subsequent β-radical fragmentation to generate lactones.
- Tnay, Ya Lin,Chiba, Shunsuke
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supporting information
p. 873 - 877
(2015/04/14)
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- Synthesis and thermal properties of a new styryl-functionalized pentafulvene glassy carbon precursor
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The first preparation of a styryl-functionalized aryl pentafulvene 4 was carried out. In the crystal structure of 4, the packing of fulvene molecules results in the shortest intermolecular contacts between aligned vinyl groups. Thermal reactivity studies of 4 (DSC and TGA, under N2) revealed a small difference between the melting point (120°C) and the Tonset for cross-linking (125°C), and provided strong evidence for the production of a network material (net4) due to reactivity of the attached styryl group. Pyrolysis of net4 under N2 gave a glassy carbon product in low yield as revealed by powder X-ray and TGA analyses (carbon yield (TGA) of 38% (900°C)).
- Shurdha, Endrit,Miller, Hannah A.,Johnson, Russell E.,Balaich, Gary J.,Iacono, Scott T.
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p. 5142 - 5147
(2014/07/08)
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- Synthesis and thermal properties of a new styryl-functionalized pentafulvene glassy carbon precursor
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The first preparation of a styryl-functionalized aryl pentafulvene 4 was carried out. In the crystal structure of 4, the packing of fulvene molecules results in the shortest intermolecular contacts between aligned vinyl groups. Thermal reactivity studies of 4 (DSC and TGA, under N2) revealed a small difference between the melting point (120 °C) and the Tonsetfor cross-linking (125 °C), and provided strong evidence for the production of a network material (net4) due to reactivity of the attached styryl group. Pyrolysis of net4 under N2gave a glassy carbon product in low yield as revealed by powder X-ray and TGA analyses (carbon yield (TGA) of 38% (900 °C)).
- Shurdha, Endrit,Miller, Hannah A.,Johnson, Russell E.,Balaich, Gary J.,Iacono, Scott T.
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p. 5142 - 5147
(2014/12/10)
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- Acid-catalyzed oxidative radical addition of ketones to olefins
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Based on a mechanistic study, we have discovered a Bronsted acid catalyzed formation of ketone radicals. This is believed to proceed via thermally labile alkenyl peroxides formed in situ from ketones and hydroperoxides. The discovery could be utilized to develop a multicomponent radical addition of unactivated ketones and tert-butyl hydroperoxide to olefins. The resulting γ-peroxyketones are synthetically useful intermediates that can be further transformed into 1,4-diketones, homoaldol products, and alkyl ketones. A one-pot reaction yielding a pharmaceutically active pyrrole is also described.
- Schweitzer-Chaput, Bertrand,Demaerel, Joachim,Engler, Hauke,Klussmann, Martin
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p. 8737 - 8740
(2014/08/18)
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- Diaryl- and triaryl-pyrrole derivatives: Inhibitors of the MDM2-p53 and MDMX-p53 protein-protein interactions
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Screening identified 2-(3-((4,6-dioxo-2-thioxotetrahydropyrimidin-5(2H)- ylidene)methyl)-2,5-dimethyl-1H-pyrrol-1-yl)-4,5,6,7-tetrahydrobenzo[b] thiophene-3-carbonitrile as an MDM2-p53 inhibitor (IC50 = 12.3 μM). MDM2-p53 and MDMX-p53 activity was seen for 5-((1-(4-chlorophenyl)-2,5- diphenyl-1H-pyrrol-3-yl)methylene)-2-thioxodihydropyrimidine-4,6(1H,5H)-dione (MDM2 IC50 = 0.11 μM; MDMX IC50 = 4.2 μM) and 5-((1-(4-nitrophenyl)-2,5-diphenyl-1H-pyrrol-3-yl)methylene)pyrimidine-2,4,6(1H, 3H,5H)-trione (MDM2 IC50 = 0.15 μM; MDMX IC50 = 4.2 μM), and cellular activity consistent with p53 activation in MDM2 amplified cells. Further SAR studies demonstrated the requirement for the triarylpyrrole moiety for MDMX-p53 activity but not for MDM2-p53 inhibition. The Royal Society of Chemistry.
- Blackburn, Tim J.,Ahmed, Shafiq,Coxon, Christopher R.,Liu, Junfeng,Lu, Xiaohong,Golding, Bernard T.,Griffin, Roger J.,Hutton, Claire,Newell, David R.,Ojo, Stephen,Watson, Anna F.,Zaytzev, Andrey,Zhao, Yan,Lunec, John,Hardcastle, Ian R.
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p. 1297 - 1304
(2013/09/12)
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- Synthesis of 1,3-diphenyl-6-alkyl/aryl-substituted fulvene chromophores: Observation of π-π Interactions in a 6-pyrene-substituted 1,3-diphenylfulvene
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The synthesis, structural, and electronic properties of nine 1,3-diphenyl-6-alkyl/aryl substituted pentafulvenes were studied. Pyrene ring π-π interactions were revealed from analysis of the experimental crystal packing of 1,3-diphenyl-6-(1-pyrene)fulvene and supporting DFT calculations. Photophysical properties derived from UV-vis and fluorescence emission measurements demonstrated tunable and low HOMO-LUMO band gaps for the series. The presented results point to a model synthetic approach for incorporation of extended π systems and donor-π-acceptor groups for fulvene-based electronic materials.
- Peloquin, Andrew J.,Stone, Rebecca L.,Avila, Sarah E.,Rudico, Erlyn R.,Horn, Christopher B.,Gardner, Kim A.,Ball, David W.,Johnson, Jane E. B.,Iacono, Scott T.,Balaich, Gary J.
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experimental part
p. 6371 - 6376
(2012/09/21)
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- Woollins reagent: A chemoselective reducing agent for 1,4-enediones and 1,4-ynediones to saturated 1,4-diones
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Woollins reagent was found to act as a highly chemoselective reagent for the reduction of a wide range of 1,4-enediones and 1,4-ynediones in methanol to afford the corresponding saturated 1,4-diketones in good yields under mild reaction conditions.
- Mandal, Madhumita,Chatterjee, Sourav,Jaisankar, Parasuraman
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supporting information
p. 2615 - 2618,4
(2012/12/12)
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- Preparation of chiral pyrrole derivatives by the Paal-Knorr reaction
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A new approach has been developed for the synthesis of N-alkylpyrroles with a chiral substituent at the nitrogen atom by the Paal-Knorr reaction using esters of amino acids as the source of chirality.
- Ryzhkov,Andreev,Belov,Kurkin,Yurovskaya
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experimental part
p. 182 - 193
(2011/12/21)
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- CRTH2 MODULATORS
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Modulators of CRTH2, particularly antagonists of CRTH2, that are useful for treating various disorders, including asthma and respiratory disorders are disclosed. The compounds fall within a genus described by formula I:
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-
Page/Page column 60-61
(2011/06/28)
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- Polarity reversal induced by electrochemically generated thiazol-2-ylidenes: The Stetter reaction
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The inversion of the normal reactivity (umpolung) of aldehydes has been induced via N-heterocyclic carbenes (NHCs) thiazol-2-ylidenes 2a or 3a, generated by simple electrolyses of solutions containing thiazolium salt 2 or 3. Accordingly, 1,4-dicarbonyl compounds have been obtained, in mild conditions and in moderate to very high yields, via 1,4-addition of the Breslow intermediates to the suitable Michael acceptor. The procedure has been performed in classical organic solvents (VOCs) as well as in room temperature ionic liquids (RTILs). The different reactivity of aliphatic aldehydes vs the one of aromatic and heteroaromatic aldehydes has been emphasized.
- Orsini, Monica,Chiarotto, Isabella,Sotgiu, Giovanni,Inesi, Achille
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experimental part
p. 3511 - 3517
(2010/07/09)
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- The cascade carbo-carbonylation of unactivated alkenes catalyzed by an organocatalyst and a transition metal catalyst: A facile approach to γ-diketones and γ-carbonyl aldehydes from arylalkenes under air
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A novel cascade carbo-carbonylation reaction of unactivated arylalkenes with ketones or aldehydes was catalyzed by an organocatalyst and a transition metal catalyst via a SOMO-enamine under air, affording a simple approach to γ-diketones and γ-carbonyl aldehydes. The Royal Society of Chemistry 2010.
- Xie, Jin,Huang, Zhi-Zhen
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supporting information; experimental part
p. 1947 - 1949
(2010/06/21)
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- An expedient route to substituted furans via olefin cross-metathesis
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The olefin cross-metathesis (CM) reaction is used extensively in organic chemistry and represents a powerful method for the selective synthesis of differentially substituted alkene products. Surprisingly, efforts to integrate this remarkable process into strategies for aromatic and heteroaromatic construction have not been reported. Such structures represent key elements of the majority of small molecule drug compounds; methods for the controlled preparation of highly substituted derivatives are essential to medicinal chemistry. Here we show that the olefin CM reaction, in combination with an acid cocatalyst or subsequent Heck arylation, provides a concise and flexible entry to 2,5-di- or 2,3,5-tri-substituted furans. These cascade processes portend further opportunities for the regiocontrolled preparation of other highly substituted aromatic and heteroaromatic classes.
- Donohoe, Timothy J.,Bower, John F.
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supporting information; experimental part
p. 3373 - 3376
(2010/08/05)
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- Unexpected TiIII/Mn-promoted pinacol coupling of ketones
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Titanocene(III) chemistry has emerged in the last decades as an indispensable tool in C-C bond-forming reactions. In this context, pinacol and related reactions allow the stereoselective synthesis of vicinal diols. In this work, we present new applications of these reactions using as starting materials aromatic ketones. Simple and smooth reaction conditions have been developed and have been applied for inter- and intramolecular processes. We also describe that although Cp2TiCl is usually used as a monoelectronic reducing agent, it can be also used as an efficient Lewis acid.
- Paradas, Miguel,Campana, Araceli G.,Estevez, Rosa E.,De Cienfuegos, Luis Alvarez,Jimenez, Tania,Robles, Rafael,Cuerva, Juan M.,Oltra, J. Enrique
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supporting information; experimental part
p. 3616 - 3619
(2009/09/06)
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- Highly selective synthesis of 1-phenylpentane-1, 4-diones, and (E)-5-hydroxy-5-phenylpent-3-en-2-ones catalyzed by organophosphorus compounds
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1-Phenylpentane-1, 4-diones, and (E)- 5-hydroxy-5-phenylpent-3-en-2-ones were synthesized via organophosphine-catalyzed addition reaction of but-3-en-2-one with aldehydes. The features of the present protocols include high selectivity, operational simplicity, atom economy, and mild reaction conditions without transition metals.
- Zhang, Qing,Qiao, Yan-Fei,Huang, Min,Liang, Hong-Dong,Zhou, Ru-Jin
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experimental part
p. 425 - 430
(2010/07/16)
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- Carbonylative 1,4-addition of potassium aryltrifluoroborates to vinyl ketones
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Potassium aryltrifluoroborates have proven to be useful reagents for the carbonylative aroylation of vinyl ketones; this study broadens the scope of potassium aryltrifluoroborates in homogeneous catalysis and shows that the solvent can act as the proton s
- Sauthier, Mathieu,Lamotte, Nicolas,Dheur, Julien,Castanet, Yves,Mortreux, Andre
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experimental part
p. 969 - 971
(2010/08/21)
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- Synthesis of furans, pyrroles and pyridazines by a ruthenium-catalysed isomerisation of alkynediols and in situ cyclisation
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Alkyne-1,4-diols are readily available substrates which are isomerised to 1,4-diketones using Ru(PPh3)3(CO)H2/xantphos as a catalyst. In situ cyclisation into furans, pyrroles and pyridazines has been achieved under suitable conditions.
- Pridmore, Simon J.,Slatford, Paul A.,Taylor, James E.,Whittlesey, Michael K.,Williams, Jonathan M.J.
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supporting information; experimental part
p. 8981 - 8986
(2009/12/27)
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