- Discovery of 7-alkyloxy- [1,2,4] triazolo[1,5-a] pyrimidine derivatives as selective positive modulators of GABAA1 and GABAA4 receptors with potent antiepileptic activity
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A series of 7-alkoxy - [1,2,4] triazolo [1, 5-a] pyrimidine derivatives were designed and synthesized. Maximal electroshock (MES) and pentylenetetrazole (PTZ) tests were utilized to access their anticonvulsant activity. Most of the series of compounds exhibited significant anti-seizure effects. Further studies demonstrated that the anticonvulsant activity of these compounds mainly depended on their allosteric potentiation of GABAA receptors. Among them, compound 10c was picked for the mechanism study due to its potent activity. The compound is more sensitive to subunit configurations of synaptic α1β2γ2 and extrasynaptic α4β3δ GABAA receptors, but there were no effects on NMDA receptors and Nav1.2 sodium channels. Meanwhile, 10c acted on the sites of GABAA receptors distinct from commonly used anticonvulsants benzodiazepines and barbiturates. Furthermore, studies from native neurons demonstrated that compound 10c also potentiated the activity of native GABAA receptors and reduced action potential firings in cultured cortical neurons. Such structural compounds may lay a foundation for further designing novel antiepileptic molecules.
- Chen, Liping,Hou, Zhipeng,Huang, Longjiang,Li, Xiufen,Lian, Chengxi,Meng, Qingfei,Wang, Yan,Wu, Jun,Yu, Haibo,Zhang, Chaoying
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- Enantioselective decarboxylative Mannich reaction of β-keto acids withC-alkynylN-BocN,O-acetals: access to chiral β-keto propargylamines
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The chiral keto-substituted propargylamines are an essential class of multifunctional compounds in the field of organic and pharmaceutical synthesis and have attracted considerable attention, but the related synthetic approaches remain limited. Therefore, a concise and efficient method for the enantioselective synthesis of β-keto propargylaminesviachiral phosphoric acid-catalyzed asymmetric Mannich reaction between β-keto acids andC-alkynylN-BocN,O-acetals as easily availableC-alkynyl imine precursors has been demonstrated here, affording a broad scope of β-ketoN-Boc-propargylamines in high yields (up to 97%) with generally high enantioselectivities (up to 97?:?3 er).
- Chen, Li-Jun,Li, Wei,Shen, Bao-Chun,Sun, Zhong-Wen,Xie, Hui-Ding,Zhang, Cong-Cong
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supporting information
p. 8607 - 8612
(2021/10/20)
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- Access to pyridines via cascade nucleophilic addition reaction of 1,2,3-triazines with activated ketones or acetonitriles
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We studied the cascade nucleophilic addition reactions of 1,2,3-triazines with activated acetonitriles or ketones, which were used to construct highly substituted pyridines that are not easily accessed by conventional methods. The strategy addressed some structural diversity issues currently facing medicinal chemistry, and the resulting pyridines could be used as convenient precursors for the synthesis of related pharmaceuticals. In particular, our method was applied to the syntheses of the marketed drug etoricoxib and several biologically important molecules in a few steps.
- Zhang, Yuan,Luo, Han,Lu, Qixing,An, Qiaoyu,Li, You,Li, Shanshan,Tang, Zongyuan,Li, Baosheng
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supporting information
p. 393 - 396
(2020/05/18)
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- Palladium Catalyzed Ring Expansion Reaction of Isoxazolones with Isocyanides: Synthesis of 1,3-Oxazin-6-One Derivatives
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A palladium catalyzed ring expansion reaction of isoxazolones with isocyanides was disclosed. In the reaction, a cascade process involving ring-opening/cyclization was suggested. The reaction features high atomic economy due to no elimination of CO2 occurred. Moreover, products obtained demonstrate aggregation-induced emission properties with relatively high solid-state emission efficiencies. (Figure presented.).
- Zhu, Yi-Ming,Zhang, Wan,Li, Hongkun,Xu, Xiao-Ping,Ji, Shun-Jun
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p. 808 - 818
(2020/12/03)
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- 1-cyclohexylpyrazolone carboxylesterase 1 inhibitor as well as preparation and application thereof
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The invention discloses a 1-cyclohexylpyrazolone carboxylesterase 1 inhibitor as well as preparation and application thereof. The structural general formula of the carboxylesterase 1 inhibitor is shown in the specification, wherein R1 and R2 are any one of phenyl, benzyl, 2-methylphenyl, 4-methylphenyl, 4-methylbenzyl and 2-naphthyl respectively. The IC50 for preparing hCES1A reaches 50 nanomoles,and the ratio of the IC50 for inhibiting hCES2A to the IC50 for inhibiting hCES1A can reach 252 times. The inhibitor can improve the oral bioavailability of carboxylic ester exogenous prodrugs by inhibiting the activity of human carboxylesterase subtype 1, or can be used as a synergist of clopidogrel, and can also effectively inhibit the generation of fat cell lipid droplets induced by a mouse preadipose 3T3-L1 cell line. According to the carboxylesterase 1 inhibitor, the raw materials are easy to obtain, the cost is low, the synthesis process is simple, and the yield is high; the inhibitionactivity is high, the selectivity is good, and the application prospect is great.
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Paragraph 0036-0040; 0085-0088
(2021/01/30)
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- Iridium-Catalyzed Enantioselective and Diastereoselective Hydrogenation of Racemic β’-Keto-β-Amino Esters via Dynamic Kinetic Resolution
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An iridium/f-diaphos catalytic system for the enantioselective hydrogenation of α-substituted β-ketoesters via dynamic kinetic resolution is reported. The desired anti β’-hydroxy-β-amino esters were obtained in moderate to good yields (60–95%) with 72–99% ees and 91:9 to 99:1 drs. This protocol tolerates various functional groups and could be easily conducted on gram scale with lower catalyst loading (TON up to 9100). (Figure presented.).
- He, Jiayin,Huang, An,Ling, Fei,Wang, Shiliang,Wang, Yifan,Wang, Ze,Zhao, Xianghua,Zhong, Weihui
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supporting information
p. 4714 - 4719
(2021/09/02)
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- Iridium(III)-Catalyzed C(3)-H Alkylation of Isoquinolines via Metal Carbene Migratory Insertion
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An Ir(III)-catalyzed C(3)-H alkylation of N-acetyl-1,2-dihydroisoquinolines with diverse acceptor-acceptor diazo compounds has been achieved under a single catalytic system via metal carbene migratory insertion. Moreover, further synthetic transformations of the alkylated products such as aromatization, selective decarboxylation, and decarbonylation lead to the formation of several synthetically viable isoquinoline derivatives having immense potentials.
- Jha, Neha,Singh, Roushan Prakash,Saxena, Paridhi,Kapur, Manmohan
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supporting information
p. 8694 - 8698
(2021/11/24)
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- Electrochemical synthesis of versatile ammonium oxides under metal catalyst-, exogenous-oxidant-, and exogenous-electrolyte-free conditions
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An electrochemical oxidative cross-coupling reaction between 2.5-substituted-pyrazolin-5-ones and ammonium thiocyanate has been developed, which resulted in a series of unprecedented cross-coupling products under metal catalyst-, exogenous-oxidant-, and exogenous-electrolyte-free conditions. It is worth noting that since the resulting cross-coupling products are nearly insoluble in MeCN, the pure product could be afforded without silica gel column purification. In addition, the prepared ammonium oxides are versatile building blocks for synthesizing functionalized pyrazole derivatives.
- Yuan, Yong,Li, Liang-Sen,Zhang, Lin,Wang, Feng,Jiang, Lin,Zuo, Lin,Wang, Qi,Hu, Jian-Guo,Lei, Aiwen
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supporting information
p. 2768 - 2771
(2021/03/23)
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- Electrochemical Oxidative Cyclization: Synthesis of Polysubstituted Pyrrole from Enamines
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A conceptually novel method for the preparation of pyrrole is described by electrochemical-oxidation-induced intermolecular annulation via enamines. In a simple undivided cell, based on a sodium acetate-facilitated, polysubstituted pyrrole derivations has been facilely synthesized under external oxidant-free condition. This electrosynthetic approach providing an environmentally benign protocol for C?C bond cross-coupling and oxidative annulation, which features unparalleled broad scope of substrates and practicality.
- Chen, Zhiwei,Shi, Guang,Tang, Wei,Sun, Jie,Wang, Wenxing
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supporting information
p. 951 - 955
(2021/02/03)
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- Rational design of triplet sensitizers for the transfer of excited state photochemistry from UV to visible
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Time Dependent Density Functional Theory has been used to assist the design and synthesis of a series thioxanthone triplet sensitizers. Calculated energies of the triplet excited state (ET) informed both the type and position of auxochromes placed on the thioxanthone core, enabling fine-tuning of the UV-vis absorptions and associated triplet energies. The calculated results were highly consistent with experimental observation in both the order of the λmax and ET values. The synthesized compounds were then evaluated for their efficacies as triplet sensitizers in a variety of UV and visible light preparative photochemical reactions. The results of this study exceeded expectations; in particular [2 + 2] cycloaddition chemistry that had previously been sensitized in the UV was found to undergo cycloaddition at 455 nm (blue) with a 2- to 9-fold increase in productivity (g/h) relative to input power. This study demonstrates the ability of powerful modern computational methods to aid in the design of successful and productive triplet sensitized photochemical reactions.
- Booker-Milburn, Kevin,Elliott, Luke D.,George, Michael W.,Kayal, Surajit
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supporting information
p. 14947 - 14956
(2020/10/13)
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- Route exploration and synthesis of the reported pyridone-based PDI inhibitor STK076545
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The enzyme protein disulfide isomerase (PDI) is essential for the correct folding of proteins and the activation of certain cell surface receptors, and is a promising target for the treatment of cancer and thrombotic conditions. A previous high-throughput screen identified the commercial compound STK076545 as a promising PDI inhibitor. To confirm its activity and support further biological studies, a resynthesis was pursued of the reported β-keto-amide with an N-alkylated pyridone at the α-position. Numerous conventional approaches were complicated by undesired fragmentations or rearrangements. However, a successful 5-step synthetic route was achieved using an aldol reaction with an α-pyridone allyl ester as a key step. An X-ray crystal structure of the final compound confirmed that the reported structure of STK076545 was achieved, however its lack of PDI activity and inconsistent spectral data suggest that the commercial structure was misassigned.
- Dockendorff, Chris,Flaumenhaft, Robert,Greve, Eric,Lin, Lin,Lindeman, Sergey V.,Scartelli, Christina
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p. 6665 - 6681
(2020/09/21)
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- Cu-Mediated Expeditious Annulation of Alkyl 3-Aminoacrylates with Aryldiazonium Salts: Access to Alkyl N2-Aryl 1,2,3-Triazole-carboxylates for Druglike Molecular Synthesis
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Alkyl N-aryl 1,2,3-triazole-carboxylates are important molecules or intermediates in medicinal chemistry, but the synthesis of N2-aryl counterparts remains elusive. Herein, we describe a Cu-mediated annulation reaction of alkyl 3-aminoacrylates with aryldiazonium salts, both of which are readily available substrates. Furthermore, alkyl 2-aminoacrylates are also viable substrates. Diverse alkyl N2-aryl 1,2,3-triazole-carboxylates and their analogues can be rapidly prepared under mild conditions. Especially, this protocol allows one to access several druglike variants of carbonic anhydrase inhibitors and celecoxib.
- Liu, Hao-Nan,Cao, Hao-Qiang,Cheung, Chi Wai,Ma, Jun-An
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supporting information
p. 1396 - 1401
(2020/02/22)
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- An efficient route for the synthesis of N-(1H-benzo[d]imidazol-2-yl)benzamide derivatives promoted by CBr4 in one pot
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A metal-free one-pot method for the synthesis of N-(1H-benzo[d]imidazol-2-yl)benzamide derivatives was proposed mediated by CBr4. The reaction went through ring formation and opening processes with only two protons leaving and the thermodynamically favorable products were selectively formed in moderate to good yields.
- Li, Songhua,Li, Yunyi,Ma, Chen,Xie, Caixia
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- Chiral Vanadyl(V) Complexes Enable Efficient Asymmetric Reduction of β-Ketoamides: Application toward (S)-Duloxetine
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High-valent chiral oxidovanadium(V) complexes derived from 3,5-substituted-N-salicylidene-l-tert-leucine were used as catalysts in asymmetric reduction of N-benzyl-β-ketoamides. Among six different solvents, three different alcohol additives, and two different boranes examined, the use of pinacolborane in tetrahydrofuran (THF) with a t-BuOH additive led to the best results at -20 °C. The corresponding β-hydroxyamides can be furnished with yields up to 92percent and an enantiomeric excess (ee) up to 99percent. We have successfully extended this catalytic protocol for the synthesis of an (S)-duloxetine precursor.
- Chen, Chien-Tien,Maity, Nabin Ch.,Agarwal, Rachit,Lai, Chien-Fu,Liao, Yiya,Yu, Wei-Ru
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supporting information
p. 6408 - 6419
(2020/07/14)
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- One-pot synthesis of β-O-4 lignin models: Via the insertion of stable 2-diazo-1,3-dicarbonyls into O-H bonds
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Because lignin is a macromolecule that is a sustainable source of aromatic compounds, model substrates are commonly used to increase our understanding of its complex structure. However, few methods have been described for the synthesis of these models. Herein, we describe a new route towards the synthesis of β-O-4 lignin models by intermolecular O-H insertion reactions with simple and stable diazocarbonyls. The benefits of this developed method were shorter reaction times and high yields, as well as mild and environmentally friendly conditions. This journal is
- Burtoloso, Antonio C. B.,De Oliveira, Gabriela P.,Dias, Rafael Mafra P.
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p. 4815 - 4823
(2020/07/13)
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- Diamine-mediated degradative dimerisation of Morita-Baylis-Hillman ketones
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A degradative dimerisation of Morita-Baylis-Hillman ketones was observed in the presence of a primary diamine. The reaction proceeded swiftly to produce methylene-bridged 1,3-dicarbonyl compounds. A brief mechanistic investigation alluded to a retro-Mannich reaction as the key step of the transformation.
- Jha, Ajit Kumar,Kumari, Anju,Easwar, Srinivasan
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supporting information
p. 2949 - 2952
(2020/03/18)
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- Discovery of [1,2,4]-triazolo [1,5-a]pyrimidine-7(4H)-one derivatives as positive modulators of GABAA1 receptor with potent anticonvulsant activity and low toxicity
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In searching for more effective and safer antiepileptic drugs, a series of 2,5-disubstituted [1,2,4]-triazolo[1,5-a]pyrimidine-7(4H)-one derivatives were designed and synthesized. Spontaneous Ca2+ oscillations (SCOs) of cortical neurons were used for in vitro phenotypic screening. Maximal electroshock test (MES) and pentylenetetrazole (PTZ) test were used to access their anticonvulsant activity, and rotarod test was used to estimate their neurotoxicity. The active compounds in in vitro model are specifically effective in pentylenetetrazole (PTZ)-induced epilepsy model but not maximal electroshock (MES) model, more importantly with lower neurotoxicity as compared to commonly used drugs. Among them, compound 5c and 5e showed significant anticonvulsant activities in PTZ-induced epilepsy model with ED50 values at 31.81 mg/kg and 40.95 mg/kg, respectively. These compounds have improved neurotoxicity with protective index (PI = TD50/ED50) values at 17.22 and 9.09, respectively. Finally we demonstrated that compound 5c and 5e mainly acted on GABAA receptor as positive modulators but not sodium channels. Thus the present study has provided potential candidates for further investigation in epilepsy.
- Huang, Longjiang,Ding, Jing,Li, Min,Hou, Zhipeng,Geng, Yanru,Li, Xiufen,Yu, Haibo
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- NEW ANALOGS AS ANDROGEN RECEPTOR AND GLUCOCORTICOID RECEPTOR MODULATORS
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The present invention relates to novel dihydropyridine derivatives of formula (I): as modulators of nuclear receptors selected from androgen receptor and glucocorticoid receptor, to processes for their preparation, to pharmaceutical compositions comprising said compounds and to the use of said for manufacturing a medicament for the treatment of pathological conditions or diseases that can improve by modulation of androgen receptor and/or glucocorticoid receptor, selected from cancer, metastasizing cancers, benign prostate hyperplasia, polycystic ovary syndrome (PCOS), hair loss, hirsutism, acne, hypogonadism, muscle wasting diseases, cachexia, Cushing's syndrome, anti-psychotic drug induced weight gain, obesity, post-traumatic stress disorder and alcoholism.
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Paragraph 0276; 0277; 0278
(2019/05/16)
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- Pd-Catalyzed Synthesis of γ-Keto Esters as Key Intermediates for the Synthesis of γ-Hydroxybutenolides
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We herein report a robust and safe palladium catalyzed domino-carbonylation/Suzuki–Miyaura cross-coupling reaction of vinyltosylates with arylboronic acids using Mo(CO)6 as CO-source. The derived γ-keto ester were subsequently cyclized under acidic conditions to obtain γ-hydroxybutenolides, an important structural motif, which occurs in biologically active natural products.
- Schacht, Mathias,Mohammadi, Djawid,Schützenmeister, Nina
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supporting information
p. 2587 - 2591
(2019/02/19)
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- Noncanonical cation-π cyclizations of alkylidene β-ketoesters: Synthesis of spiro-fused and bridged bicyclic ring systems
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Three cation-π cyclization cascades initiated at alkylidene β-ketoesters bearing pendent alkenes are described. Depending upon the alkene substitution pattern and the reaction conditions employed, it is possible to achieve selective synthesis of the three different types of products, including 1-halo-3-carbomethoxycyclohexanes, spiro-fused tricyclic systems, and [4.3.1] bridged bicyclic ring systems. All three reactions begin with 6-endo addition of an olefin to the alkylidene β-ketoester electrophile, followed by one of three different cation capture events.
- Parsons, Dylan E.,Frontier, Alison J.
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supporting information
p. 2008 - 2012
(2019/03/26)
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- Synthesis and in vitro anti-epileptic activities of novel [1,2,4]-triazolo[1,5-a]pyrimidin-7(4H)-one derivatives
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In this investigation, eight novel 2,5-disubstituted [1,2,4]-triazolo[1,5-a]pyrimidin-7(4H)-one and eight novel 2,5-disubstituted [1,2,4]-triazolo[1,5-a]pyrimidine amine derivatives were synthesized based on the novel marine natural product Essramycin. Their anti-epileptic activities were evaluated by 4-aminopyridine (4-AP)-induced hyper excitability model in primary cultured neocortical neurons. Five compounds with [1,2,4]-triazolo[1,5-a]pyrimidin-7(4H)-one skeleton showed remarkable anti-epileptic activities. The preliminary structure–activity relationship (SAR) showed that the pyrimidine-7(4H)-one motif is the necessary “active core” of anti-epileptic activity. To understand the action mechanism of anti-epileptic activity of [1,2,4]-triazolo[1,5-a]pyrimidin-7(4H)-one compounds, docking studies using the model of GABAA as docking scaffolds were performed and the docking results were in concordance with the experiment observations. (Figure presented.).
- Ding, Jing,Cao, Feng-De,Geng, Yan-Ru,Tian, Yuan,Li, Peng,Li, Xiu-Fen,Huang, Long-Jiang
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p. 1190 - 1204
(2019/01/05)
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- Direct Access to 1,1-Dicarbonyl Sulfoxonium Ylides from Aryl Halides or Triflates: Palladium-Catalyzed Carbonylation
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The synthesis of 1,1-dicarbonyl sulfoxonium ylides by palladium-catalyzed carbonylation of aryl halides or triflates with α-carbonyl sulfoxonium ylides has been developed for the first time. This method provides a general approach to synthetically useful 1,1-dicarbonyl sulfoxonium ylides in high efficiency. The protocol displays a wide substrate scope, showing that the resulting 1,1-dicarbonyl sulfoxonium ylides have been converted into the corresponding 1,3-dicarbonyl compounds.
- Yuan, Yang,Wu, Xiao-Feng
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supporting information
p. 5310 - 5314
(2019/09/06)
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- Synthesis of novel proxyphylline derivatives with dual Anti-Candida albicans and anticancer activity
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Three out of 16 newly synthesized 1,3-dimethylxanthine derivatives (proxyphylline analogues) exhibited consistencies between antifungal and anticancer properties. Proxyphylline possessing 1-(10H-phenothiazin-10-yl)propan-2-yl (6) and polybrominated benzimidazole (41) or benzotriazole moiety (42) remained selectively cidal against Candida albicans (lg R ≥ 3 at conc. of 31, 36 and 20 μM, respectively) however not against normal mammalian Vero cell line in vitro (IC50 ≥ 280 μM) and Galleria mellonella in vivo. These compounds also displayed moderate antineoplastic activity against human breast adenocarcinoma (MCF-7) cell line (EC50 = 80 μM) and high against peripheral blood T lymphoblast (CCRF-CEM) (EC50 = 6.3–6.5 μM). In addition, 6 and 42 exerted: (1) dual activity against fungal adhesion and damage mature biofilm; (2) necrosis of planktonic cells due to loss of membrane function and of structural integrity; (3) biochemical (inhibition of sessile cell respiration) and morphological changes in cell wall polysaccharide contents. Therefore, leading proxyphylline derivatives can be employed to prevent cancer-associated biofilm Candida infections.
- Borowiecki, Pawe?,Wińska, Patrycja,Bretner, Maria,Gizińska, Ma?gorzata,Koronkiewicz, Miros?awa,Staniszewska, Monika
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p. 307 - 333
(2018/03/21)
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- Reinventing the de Mayo reaction: Synthesis of 1,5-diketones or 1,5-ketoesters via visible light [2+2] cycloaddition of β-diketones or β-ketoesters with styrenes
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A visible light mediated De Mayo reaction between 1,3-diketones and styrenes following a [2+2] cycloaddition pathway via a photosensitization mechanism gives access to 1,5-diketones. The reaction has been applied to substituted styrenes and aryl- and alkyl-substituted ketones. Moreover, the method converts β-ketoesters, β-amido esters, and β-cyano ketones. Seven membered rings, a frequent structural motif of natural products, are also accessible using this methodology.
- Martinez-Haya, Rebeca,Marzo, Leyre,K?nig, Burkhard
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supporting information
p. 11602 - 11605
(2018/10/31)
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- PhIO/Et3N ? 3HF-Mediated Formation of Fluorinated 2H-Azirines via Domino Fluorination/Azirination Reaction of Enamines
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A variety of enamine carboxylic esters and enaminones were converted to the biologically interesting fluorinated 2H-azirines through reactions with PhIF2 generated in situ by PhIO and Et3N ? 3HF in 1,2-dichroloethane, which features the hypervalent iodine reagents-mediated introduction of fluorine atom and formation of the 2H-azirine skeleton under metal-free conditions. The domino reaction is postulated to proceed via a PhIF2-mediated oxidative fluorination and a subsequent azirination of the fluorinated enamine intermediates. (Figure presented.).
- Zhang, Yong,Zhao, Xiaoyuan,Zhuang, Chen,Wang, Senlin,Zhang-Negrerie, Daisy,Du, Yunfei
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supporting information
p. 2107 - 2112
(2018/04/19)
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- Synthesis of trifluoromethylated 2H-azirines through Togni reagent-mediated trifluoromethylation followed by PhIO-mediated azirination
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The reaction of enamine compounds with the Togni reagent in the presence of CuI afforded β-trifluoromethylated enamine intermediates, which were converted directly to biologically interesting trifluoromethylated 2H-azirines by an iodosobenzene (PhIO)-mediated intramolecular azirination in a one-pot process.
- Sun, Jiyun,Zhen, Xiaohua,Ge, Huaibin,Zhang, Guangtao,An, Xuechan,Du, Yunfei
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supporting information
p. 1452 - 1458
(2018/07/05)
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- Quinone-Fused Pyrazoles through 1,3-Dipolar Cycloadditions: Synthesis of Tricyclic Scaffolds and in vitro Cytotoxic Activity Evaluation on Glioblastoma Cancer Cells
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A novel and straightforward synthesis of highly substituted isoquinoline-5,8-dione fused tricyclic pyrazoles is reported. The key step of the synthetic sequence is a regioselective, Ag2CO3 promoted, 1,3-dipolar cycloaddition of C-heteroaryl-N-aryl nitrilimines and substituted isoquinoline-5,8-diones. The broad functional group tolerability and mild reaction conditions were found to be suitable for the preparation of a small library of compounds. These scaffolds were designed to interact with multiple biological residues, and two of them, after brief synthetic elaborations, were analyzed by molecular docking studies as potential anticancer drugs. In vitro studies confirmed the potent anticancer effects, showing promising IC50 values as low as 2.5 μm against three different glioblastoma cell lines. Their cytotoxic activity was finally positively correlated to their ability to inhibit PI3K/mTOR kinases, which are responsible for the regulation of diverse cellular processes in human cancer cells.
- Bertuzzi, Giulio,Crotti, Simone,Calandro, Pierpaolo,Bonini, Bianca Flavia,Monaco, Ilaria,Locatelli, Erica,Fochi, Mariafrancesca,Zani, Paolo,Strocchi, Elena,Mazzanti, Andrea,Chiariello, Mario,Franchini, Mauro Comes
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supporting information
p. 1744 - 1750
(2018/09/11)
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- Rhodium-Catalyzed Enantioconvergent Isomerization of Homoallylic and Bishomoallylic Secondary Alcohols
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We present herein an unprecedented enantioselective isomerization of homoallylic and bishomoallylic secondary alcohols, catalyzed by a commercially available rhodium-complex and a base. This catalytic redox-neutral process provides an effective access to chiral ketones in high efficiency and enantioselectivity, without the use of any stoichiometric reagent or generation of any waste. For the reaction of homoallylic alcohols, this system achieved not only a stereoconvergent access to chiral ketones bearing a β-stereocenter (up to 95%, 86% ee) but also a concomitant oxidative kinetic resolution of the alcohol substrates (S > 20). In the case of bishomoallylic alcohols, an intriguing ligand-induced divergent reactivity was observed. A terminal-to-internal alkene isomerization promoted by Rh/L7 followed by redox isomerization using Rh/BINAP system produced chiral ketones bearing a γ-stereocenter with high yield and enantioselectivity. Mechanistic studies provided strong support for the redox-isomerization pathway with chain walking of the key alkyl-Rh intermediate.
- Huang, Rui-Zhi,Lau, Kai Kiat,Li, Zhaofeng,Liu, Tang-Lin,Zhao, Yu
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supporting information
p. 14647 - 14654
(2018/11/06)
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- Iridium-Catalyzed Asymmetric Hydrogenation of Tetrasubstituted α-Fluoro-β-enamino Esters: Efficient Access to Chiral α-Fluoro-β-amino Esters with Two Adjacent Tertiary Stereocenters
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An iridium-catalyzed highly efficient asymmetric hydrogenation of challenging tetrasubstituted α-fluoro-β-enamino esters was successfully developed using bisphosphine-thiourea (ZhaoPhos) as the ligand, which prepared a series of chiral α-fluoro-β-amino esters containing two adjacent tertiary stereocenters with high yields and excellent diastereoselectivities/enantioselectivities (73%-99% yields, >25:1 dr, 91%>99% ee, and turnover number (TON) values up to 8600), and no defluorinate byproduct was detected.
- Han, Zhengyu,Guan, Yu-Qing,Liu, Gang,Wang, Rui,Yin, Xuguang,Zhao, Qingyang,Cong, Hengjiang,Dong, Xiu-Qin,Zhang, Xumu
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supporting information
p. 6349 - 6353
(2018/10/15)
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- SO2F2-Mediated Oxidative Dehydrogenation and Dehydration of Alcohols to Alkynes
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Direct synthesis of alkynes from inexpensive, abundant alcohols was achieved in high yields (greater than 40 examples, up to 95% yield) through a SO2F2-promoted dehydration and dehydrogenation process. This straightforward transformation of sp3-sp3 (C-C) bonds to sp-sp (C=C) bonds requires only inexpensive and readily available reagents (no transition metals) under mild conditions. The crude alkynes are sufficiently free of impurities to permit direct use in further transformations, as illustrated by regioselective Huisgen alkyne-azide cycloaddition reactions with PhN3 to give 1,4-substituted 1,2,3-traiazoles (16 examples, up to 92% yield) and Sonogashira couplings (10 examples, up to 77% yield).
- Zha, Gao-Feng,Fang, Wan-Yin,Li, You-Gui,Leng, Jing,Chen, Xing,Qin, Hua-Li
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supporting information
p. 17666 - 17673
(2019/01/04)
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- Br?nsted Acid-Catalyzed Carbonyl-Olefin Metathesis inside a Self-Assembled Supramolecular Host
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Carbonyl–olefin metathesis represents a powerful yet underdeveloped method for the formation of carbon–carbon bonds. So far, no Br?nsted acid based method for the catalytic carbonyl–olefin metathesis has been described. Herein, a cocatalytic system based on a simple Br?nsted acid (HCl) and a self-assembled supramolecular host is presented. The developed system compares well with the current benchmark catalyst for carbonyl–olefin metathesis in terms of substrate scope and yield of isolated product. Control experiments provide strong evidence that the reaction proceeds inside the cavity of the supramolecular host. A mechanistic probe indicates that a stepwise reaction mechanism is likely.
- Catti, Lorenzo,Tiefenbacher, Konrad
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supporting information
p. 14589 - 14592
(2018/01/27)
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- TBHP/AIBN-Mediated Synthesis of 2-Amino-thioazoles from Active Methylene Ketones and Thiourea under Metal-free Conditions
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A new oxidative system of tert-butyl hydroperoxide (TBHP)/azodiisobutyronitrile (AIBN) has been used for the first time for a convenient, metal-free synthesis of substituted 2-aminothioazoles from active methylene ketone derivatives and thiourea. The reaction is postulated to proceed via an oxidative cyclization initiated by a radical process and followed by a condensation reaction.
- Sun, Jiyun,Ge, Huaibin,Zhen, Xiaohua,An, Xuechan,Zhang, Guangtao,Zhang-Negrerie, Daisy,Du, Yunfei,Zhao, Kang
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p. 2107 - 2114
(2018/03/26)
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- Rhodium-catalyzed asymmetric hydrogenation of tetrasubstituted β-acetoxy-α-enamido esters and efficient synthesis of droxidopa
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A rhodium-catalyzed asymmetric hydrogenation of challenging tetrasubstituted β-acetoxy-α-enamido esters was developed, giving chiral β-acetoxy-α-amido esters in high yields with excellent enantioselectivities (up to >99% ee). The products could be easily transformed to β-hydroxy-α-amino acid derivatives which are valuable chiral building blocks and a novel route for the synthesis of droxidopa was also developed.
- Guan, Yu-Qing,Gao, Min,Deng, Xu,Lv, Hui,Zhang, Xumu
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supporting information
p. 8136 - 8139
(2017/07/24)
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- α-Alkylidene-γ-butyrolactone Formation via Bi(OTf)3-Catalyzed, Dehydrative, Ring-Opening Cyclizations of Cyclopropyl Carbinols: Understanding Substituent Effects and Predicting E/Z Selectivity
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A Bi(OTf)3-catalyzed ring-opening cyclization of (hetero)aryl cyclopropyl carbinols to form α-alkylidene-γ-butyrolactones (ABLs) is reported. This transformation represents different chemoselectivity from previous reports that demonstrated formation of (hetero)aryl-fused cyclohexa-1,3-dienes upon acid-promoted cyclopropyl carbinol ring opening. ABLs are obtained in up to 89% yield with a general preference for the E-isomers. Mechanistically, Bi(OTf)3 serves as a stable and easy to handle precursor to TfOH. TfOH then catalyzes the formation of cyclopropyl carbinyl cations, which undergo ring opening, intramolecular trapping by the neighboring ester group, subsequent hydrolysis, and loss of methanol resulting in the formation of the ABLs. The nature and relative positioning of the substituents on both the carbinol and the cyclopropane determine both chemo- and stereoselective outcomes. Carbinol substituents determine the extent of cyclopropyl carbinyl cation formation. The cyclopropane donor substituents determine the overall reaction chemoselectivity. Weakly stabilizing or electron-poor donor groups provide better yields of the ABL products. In contrast, copious amounts of competing products are observed with highly stabilizing cyclopropane donor substituents. Finally, a predictive model for E/Z selectivity was developed using DFT calculations.
- Sandridge, Matthew J.,McLarney, Brett D.,Williams, Corey W.,France, Stefan
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p. 10883 - 10897
(2017/10/27)
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- Nickel-catalyzed enantioselective hydrogenation of β-(acylamino)acrylates: Synthesis of chiral β-amino acid derivatives
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The nickel-catalyzed asymmetric hydrogenation of β-(acylamino)acrylates has been developed, affording chiral β-amino acid derivatives with excellent yields (95-99% yield) and enantioselectivities (97-99% ee). With the Ni-Binapine system, high enantioselectivities (98-99% ee) have also been obtained in the hydrogenation of Z/E isomeric mixtures of β-alkyl and β-aryl β-(acylamino)acrylates. The synthesis of chiral β-amino acid derivatives on a gram scale has also been achieved with 0.2 mol % catalyst loading.
- Li, Xiuxiu,You, Cai,Li, Shuailong,Lv, Hui,Zhang, Xumu
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supporting information
p. 5130 - 5133
(2017/11/06)
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- Copper-Catalysed Decarboxylative Trifluoromethylation of β-Ketoacids
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An efficient method for Cu-catalyzed decarboxylative trifluoromethylation of β-ketoacids to achieve α-trifluoromethyl ketones was developed. A wide variety of synthetically useful α-trifluoromethyl ketones were obtained in modest to good yields under mild reaction conditions. The present method also exhibits good functional-group compatibility.
- Xu, Xiaolan,Chen, Huanhuan,He, Jianbo,Xu, Huajian
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supporting information
p. 1665 - 1668
(2017/10/05)
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- Wacker-Type Oxidation Using an Iron Catalyst and Ambient Air: Application to Late-Stage Oxidation of Complex Molecules
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A practical and general iron-catalyzed Wacker-type oxidation of olefins to ketones is presented, and it uses ambient air as the sole oxidant. The mild oxidation conditions enable exceptional functional-group tolerance, which has not been demonstrated for any other Wacker-type reaction to date. The inexpensive and nontoxic reagents [iron(II) chloride, polymethylhydrosiloxane, and air] can, therefore, also be employed to oxidize complex natural-product-derived and polyfunctionalized molecules.
- Liu, Binbin,Jin, Fengli,Wang, Tianjiao,Yuan, Xiaorong,Han, Wei
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supporting information
p. 12712 - 12717
(2017/09/11)
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- Cooperative Indium(III)/Silver(I) System for Oxidative Coupling/Annulation of 1,3-Dicarbonyls and Styrenes: Construction of Five-Membered Heterocycles
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A cooperative indium(III)/silver(I) system for the synthesis of various five-membered heterocycles, including dihydrofurans, pyrroles, spirolactones, and spiroiminolactones, through the sequential oxidative coupling/annulation reaction of 1,3-dicarbonyl compounds with styrenes has been developed. Four different heterocyclic systems were successfully synthesized depending on the substitution pattern of the substrates using readily available starting materials. This system has the advantages of a broad substrate scope, moderate to good chemical yields, an operationally easy and simple procedure, and short reaction times. (Figure presented.) .
- Ko, Tae Yun,Youn, So Won
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supporting information
p. 1934 - 1941
(2016/07/06)
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- Calcium-catalyzed, dehydrative, ring-opening cyclizations of cyclopropyl carbinols derived from donor-acceptor cyclopropanes
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A calcium-catalyzed, dehydrative, ring-opening cyclization of (hetero)aryl cyclopropyl carbinols is reported. The cyclopropyl carbinols are prepared directly from the corresponding donor-acceptor (D-A) cyclopropanes. The calcium catalyst catalyzes the formation of putative (hetero)aryl cyclopropyl carbinyl cations that undergo ring-opening to allylcarbinyl cations. Subsequent intramolecular Friedel-Crafts reaction affords (hetero)aryl-fused cyclohexa-1,3-dienes in up to 97% yield. This approach represents the first example of catalysis for this intramolecular, dehydrative ring-opening cyclization and outperforms the previous reports using stoichiometric Lewis acids.
- Sandridge, Matthew J.,France, Stefan
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supporting information
p. 4218 - 4221
(2016/09/09)
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- Oxidative Coupling of Enamines and Disulfides via Tetrabutylammonium Iodide/tert-Butyl Hydroperoxide-Mediated Intermolecular Oxidative C(sp2) S Bond Formation Under Transition Metal-Free Conditions
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The reaction of enamine compounds with disulfides in the presence of tert-butyl hydroperoxide and a catalytic amount of tetrabutylammonium iodide conveniently afforded a variety of α-thioenamine compounds through the intermolecular oxidative C(sp2) S coupling. Incorporating both of the sulfide moieties in the disulfides into the final products under oxidative conditions, this novel approach exhibits the feature of atom efficiency. A radical mechanistic pathway for the reaction process has been proposed. (Figure presented.) .
- Sun, Jiyun,Zhang-Negrerie, Daisy,Du, Yunfei
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supporting information
p. 2035 - 2040
(2016/07/16)
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- Stereoselective Michael Halogenation Initiated Ring Closure (MHIRC) Synthesis of Spirocyclopropanes from Benzylidenemalononitriles and 3-Arylisoxazol-5(4H)-ones
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The new chemical cascade reaction was found: the direct formation of substituted 4-oxo-2,7-diaryl-5-oxa-6-azaspiro[2.4]hept-6-ene-1,1-dicarbonitriles from benzylidenemalononitriles and 3-aryl-2-isoxazol-5(4H)-ones. The action of bromine on the equimolar mixture of benzylidenemalononitrile and 3-aryl-2-isoxazol-5(4H)-one in the basic alcohol solution results in stereoselective formation of spirobicycle containing the 2-isoxazolin-5-one and the cyclopropane fragments in 53-92% yields. Thus, the new simple and efficient ‘one-pot’ approach to substituted (2R*,3R*)-4-oxo-2,7-diaryl-5-oxa-6-azaspiro[2.4]hept-6-ene-1,1-dicarbonitriles was found directly from simple and reasonable starting compounds as benzylidenemalonitriles and 3-aryl-2-isoxazol-5(4H)-ones.
- Vereshchagin, Anatoly N.,Elinson, Michail N.,Korshunov, Alexander D.,Anisina, Yuliya E.,Novikov, Roman A.,Goloveshkin, Alexander S.,Bushmarinov, Ivan S.,Zlotin, Sergey G.,Egorov, Mikhail P.
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supporting information
p. 2489 - 2493
(2016/10/21)
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- Enantioselective hydrogenation of β-aryl-β-ketoester over α-hydroxy acid-modified Raney nickel catalysts: competitive hydrogenation with methyl acetoacetate
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The enantioselective hydrogenation of the aromatic β-ketoesters, methyl 3-phenyl-3-oxypropanoate (1) and its p-methoxy-analogue (2), was studied over tartaric acid-modified Raney nickel catalysts. A competitive hydrogenation approach was used to clarify the catalytic behaviors of the enantio-differentiating hydrogenation of aromatic β-ketoesters over tartaric acid-modified Raney nickel, malic acid-modified Raney nickel, and unmodified Raney nickel in comparison with aliphatic one, represented by methyl acetoacetate. We found that the enantioselectivity could be elucidated by the interaction modes between the surface modifier, Ni metal surface, and the substrate as well as the keto/enol ratio of the substrate. We suggest that the moderate enantioselectivity of 1 over tartaric acid-modified Raney nickel is the result of distorted, weak two-point hydrogen bond interactions with surface tartrate due to unfavorable phenyl–Ni metal surface interactions. The p-methoxy group of 2 suppresses the phenyl–Ni metal surface interactions, resulting in an increase in the enantioselectivity of 2 over tartaric acid-modified Raney nickel. Ligand acceleration effects were observed with methyl acetoacetate and 2 but not with 1.
- Choliq, Azka Azkiya,Watanabe, Junya,Misaki, Tomonori,Okamoto, Yasuaki,Sugimura, Takashi
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p. 657 - 662
(2016/07/11)
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- The guareschi pyridine scaffold as a valuable platform for the identification of selective PI3K inhibitors
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A novel series of 4-aryl-3-cyano-2-(3-hydroxyphenyl)-6-morpholino-pyridines have been designed as potential phosphatidylinositol-3-kinase (PI3K) inhibitors. The compounds have been synthesized using the Guareschi reaction to prepare the key 4-aryl- 3-cyano-2,6-dihydroxypyridine intermediate. A different selectivity according to the nature of the aryl group has been observed. Compound 9b is a selective inhibitor against the PI3Kα isoform, maintaining a good inhibitory activity. Docking studies were also performed in order to rationalize its profile of selectivity.
- Galli, Ubaldina,Ciraolo, Elisa,Massarotti, Alberto,Margaria, Jean Piero,Sorba, Giovanni,Hirsch, Emilio,Tron, Gian Cesare
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supporting information
p. 17275 - 17287
(2015/12/01)
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- Direct oxidative coupling of enamines and electron-deficient amines: TBAI/TBHP-mediated synthesis of substituted diaminoalkenes under metal-free conditions
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A metal-free cross-coupling of enamines and electron-de fi cient amines through oxidative C(sp2)-N bond formation has been realized by using TBAI as catalyst and TBHP as oxidant. This novel strategy allows for an efficient organocatalytic synthesis of the synthetically useful diaminoalkene derivatives and is highlighted by appealing features such as readily available of the starting materials, wide substrate scope and transition-metal-free characteristics. (Chemical Equation Presented).
- Yuan, Yucheng,Hou, Wenjuan,Zhang-Negrerie, Daisy,Zhao, Kang,Du, Yunfei
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supporting information
p. 5410 - 5413
(2015/01/09)
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- Synthesis of enantiopure β-amino amides via a practical reductive amination of the corresponding β-keto amides
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A convenient and efficient reductive amination for the preparation of chiral β-amino amides is developed utilizing microwave heating. A variety of chiral β-keto amides react with ammonium acetate and sodium cyanoborohydride to afford the desired functionalized amines in good yields. This improved procedure takes advantage of microwave heating to significantly accelerate the reaction and offers a convenient and effective method to access some interesting molecules containing primary amine functionalities.
- Mtat, Dalila,Touati, Ridha,Ben Hassine, Béchir
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p. 6354 - 6358
(2014/12/11)
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- Base initiated aromatization/CO bond formation: A new entry to O-pyrazole polyfluoroarylated ethers
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A base initiated intermolecular SNAr reaction of pyrazolones with polyfluoroarenes was developed. The process involved the isomerization aromatization of pyrazolone followed by the CO bond formation via the selective CF bond cleavage. With this strategy, a wide range of O-pyrazole polyfluoroarylated ethers bearing diverse functional groups were synthesized in mild to good yields. Additionally, our method was also applied to the isoxazol substrates.
- Tang, Xiangyang,Chang, Jing,Liu, Cuibo,Zhang, Bin
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supporting information
p. 6534 - 6537
(2015/01/08)
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- Rhodium-catalyzed enantioseletive hydrogenation of tetrasubstituted α-acetoxy β-enamido esters: A new approach to chiral α-hydroxyl-β-amino acid derivatives
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Asymmetric hydrogenation of tetrasubtitued α-acetoxy β-enamido esters with rhodium catalysts based on chiral diphosphine ligands provides an efficient and concise route to the synthesis of chiral α-hydroxyl-β-amino acid derivatives in excellent enantioselectivities. The products are valuable chiral building blocks in many biologically active compounds and have important applications in organic synthesis.
- Wang, Qingli,Huang, Wenhua,Yuan, Haoquan,Cai, Qin,Chen, Liming,Lv, Hui,Zhang, Xumu
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supporting information
p. 16120 - 16123
(2015/02/18)
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- HTS followed by NMR based counterscreening. Discovery and optimization of pyrimidones as reversible and competitive inhibitors of xanthine oxidase
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The identification of novel, non-purine based inhibitors of xanthine oxidase is described. After a high-throughput screening campaign, an NMR based counterscreen was used to distinguish actives, which interact with XO in a reversible manner, from assay artefacts. This approach identified pyrimidone 1 as a reversible and competitive inhibitor with good lead-like properties. A hit to lead campaign gave compound 41, a nanomolar inhibitor of hXO with efficacy in the hyperuricemic rat model after oral dosing.
- Even?s, Johan,Edfeldt, Fredrik,Lepist?, Matti,Svitacheva, Naila,Synnergren, Anna,Lundquist, Britta,Gr?nse, Mia,R?nnholm, Anna,Varga, Mikael,Wright, John,Wei, Min,Yue, Sherrie,Wang, Junfeng,Li, Chong,Li, Xuan,Chen, Gang,Liao, Yong,Lv, Gang,Tj?rnebo, Ann,Narjes, Frank
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supporting information
p. 1315 - 1321
(2014/03/21)
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- Steric vs. electronic effects in the Lactobacillus brevis ADH-catalyzed bioreduction of ketones
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Lactobacillus brevis ADH (LBADH) is an alcohol dehydrogenase that is commonly employed to reduce alkyl or aryl ketones usually bearing a methyl, an ethyl or a chloromethyl as a small ketone substituent to the corresponding (R)-alcohols. Herein we have tested a series of 24 acetophenone derivatives differing in their size and electronic properties for their reduction employing LBADH. After plotting the relative activity against the measured substrate volumes we observed that apart from the substrate size other effects must be responsible for the activity obtained. Compared to acetophenone (100% relative activity), other small substrates such as propiophenone, α,α, α-trifluoroacetophenone, α-hydroxyacetophenone, and benzoylacetonitrile had relative activities lower than 30%, while medium-sized ketones such as α-bromo-, α,α-dichloro-, and α,α-dibromoacetophenone presented relative activities between 70% and 550%. Moreover, the comparison between the enzymatic activity and the obtained final conversions using an excess or just 2.5 equiv. of the hydrogen donor 2-propanol, denoted again deviations between them. These data supported that these hydrogen transfer (HT) transformations are mainly thermodynamically controlled. For instance, bulky α-halogenated derivatives could be quantitatively reduced by LBADH even employing 2.5 equiv. of 2-propanol independently of their kinetic values. Finally, we found good correlations between the IR absorption band of the carbonyl groups and the degrees of conversion obtained in these HT processes, making this simple method a convenient tool to predict the success of these transformations. The Royal Society of Chemistry.
- Rodriguez, Cristina,Borzecka, Wioleta,Sattler, Johann H.,Kroutil, Wolfgang,Lavandera, Ivan,Gotor, Vicente
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supporting information
p. 673 - 681
(2014/01/06)
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- Studies on the chemoenzymatic synthesis of (R)- and (S)-methyl 3-aryl-3-hydroxypropionates: The influence of toluene-pretreatment of lipase preparations on enantioselective transesterifications
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Two series (para- and meta-substituted) of racemic methyl esters of 3-aryl-3-hydroxypropionic acid were prepared after which the enantiomers were separated by an enzyme-catalyzed transesterification. Several lipases were investigated as the catalyst. The influence of the enzyme pretreatment, as well as substrate concentration, reaction temperature, stirring manner, and substrate conversion on the stereochemical outcome of the biotransformation process were investigated in detail. The best results were achieved by using solvent-pretreated lipase from Pseudomonas fluorescens or Burkholderia cepacia suspended in toluene, and vinyl acetate as the acetyl group donor.
- Borowiecki, Pawel,Bretner, Maria
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p. 925 - 936
(2013/09/23)
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