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Fluorinated N, N -dialkylaminostilbenes for wnt pathway inhibition and colon cancer repression
Colorectal cancer (CRC) is the second leading cause of cancer-related mortality in the USA. CRC is initiated by mutations of the tumor suppressor gene, adenomatous polyposis coli (APC), or β-catenin gene. These mutations stabilize β-catenin and constitutively activate Wnt/β-catenin target genes, such as c-Myc and cyclin D1, ultimately leading to cancer. Naturally occurring stilbene derivatives, resveratrol and pterostilbene, inhibit Wnt signaling and repress CRC cell proliferation but are ineffective at concentrations less than 10 μM. To understand the structure-activity relationship within these stilbene derivatives and to develop more efficacious Wnt inhibitors than these natural products, we synthesized and evaluated a panel of fluorinated N,N-dialkylaminostilbenes. Among this panel, (E)-4-(2,6-difluorostyryl)-N,N-dimethylaniline (4r) inhibits Wnt signaling at nanomolar levels and inhibits the growth of human CRC cell xenografts in athymic nude mice at a dosage of 20 mg/kg. These fluorinated N,N-dialkylaminostilbenes appear to inhibit Wnt signaling downstream of β-catenin, probably at the transcriptional level.
Zhang, Wen,Sviripa, Vitaliy,Kril, Liliia M.,Chen, Xi,Yu, Tianxin,Shi, Jiandang,Rychahou, Piotr,Evers, B. Mark,Watt, David S.,Liu, Chunming
p. 1288 - 1297
(2011)
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Bimetallic Ni–Pd Synergism—Mixed Metal Catalysis of the Mizoroki-Heck Reaction and the Suzuki–Miyaura Coupling of Aryl Bromides
Abstract: A combination of Pd and Ni complexes activated aryl bromides for the thermal Mizoroki-Heck reaction and Suzuki coupling giving high yields in short reaction times. A thermal redox mechanism probably occurs whereby Ni complex transfers electron and reduces the Pd (II) to Pd (0) which then takes the reactants through the standard protocol of oxidative-addition, migratory insertion and reductive elimination, typical for the Mizoroki-Heck reaction and the Suzuki coupling. Graphic Abstract: [Figure not available: see fulltext.]
Kashid, Abhijit A.,Patil, Dharmaraj J.,Mali, Ramling D.,Patil, Vijay P.,Neethu,Meroliya, Heena K.,Waghmode, Shobha A.,Iyer, Suresh
p. 353 - 358
(2020/08/05)

Chemoselective acid-catalyzed [4 + 2]-cycloaddition reactions of: Ortho -quinone methides and styrenes/stilbenes/cinnamates
ortho-Quinone methides (o-QMs) generated from the corresponding benzyl acetate precursors chemoselectively underwent the formal [4 + 2]-cycloadditions with the olefin of styrene, stilbene, or cinnamate derivatives by using different transition metal salts or Br?nsted acids. Such selectivity was obtained when these olefins either separately acted as the dienophiles or were simultaneously present on the same dienophiles. Complete selectivity was also achieved between the stilbene olefin and acetylene to furnish the key chroman intermediate for the subsequent ring-closing metathesis (RCM), affording the corresponding tetracyclic 5H-dihydronaphtho[1,2-c]chromene. This journal is
Akkarasereenon, Kornkamon,Ploypradith, Poonsakdi,Ruchirawat, Somsak,Tangdenpaisal, Kassrin
supporting information
p. 8854 - 8866
(2020/11/23)

Self-Assembled Multilayer Iron(0) Nanoparticle Catalyst for Ligand-Free Carbon-Carbon/Carbon-Nitrogen Bond-Forming Reactions
Self-assembled multilayer iron(0) nanoparticles (NPs, 6-10 nm), namely, sulfur-modified Au-supported Fe(0) [SAFe(0)], were developed for ligand-free one-pot carbon-carbon/carbon-nitrogen bond-forming reactions. SAFe(0) was successfully prepared using a well-established metal-nanoparticle catalyst preparative protocol by simultaneous in situ metal NP and nanospace organization (PSSO) with 1,4-bis(trimethylsilyl)-1,4-dihydropyrazine (Si-DHP) as a strong reducing agent. SAFe(0) was easy to handle in air and could be recycled with a low iron-leaching rate in reaction cycles.
Akiyama, Toshiki,Arisawa, Mitsuhiro,Haneoka, Hitoshi,Harada, Kazuo,Hasegawa, Jun-Ya,Honma, Tetsuo,Mashima, Kazushi,Sato, Yoshihiro,Shimoda, Shuhei,Shio, Yasunori,Suzuki, Takeyuki,Tamenori, Yusuke,Tsurugi, Hayato,Tsuruta, Kazuki,Wada, Yuki,Yamada, Makito
supporting information
p. 7244 - 7249
(2020/10/12)

A Simple Nickel Catalyst Enabling an E-Selective Alkyne Semihydrogenation
Stereoselective alkyne semihydrogenations are attractive approaches to alkenes, which are key building blocks for synthesis. With regards to the most atom-economic reducing agent dihydrogen (H2), only few catalysts for the challenging E-selective alkyne semihydrogenation have been disclosed, each with a unique substrate scope profile. Here, we show that a commercially available nickel catalyst facilitates the E-selective alkyne semihydrogenation of a wide variety of substituted internal alkynes. This results in a simple and broadly applicable overall protocol to stereoselectively access E-alkenes employing H2, which could serve as a general method for synthesis.
Thiel, Niklas O.,Kaewmee, Benyapa,Tran Ngoc, Trung,Teichert, Johannes F.
p. 1597 - 1603
(2020/02/05)

Palladium-Based Catalysts Supported by Unsymmetrical XYC–1 Type Pincer Ligands: C5 Arylation of Imidazoles and Synthesis of Octinoxate Utilizing the Mizoroki–Heck Reaction
A series of new unsymmetrical (XYC–1 type) palladacycles (C1–C4) were designed and synthesized with simple anchoring ligands L1–4H (L1H = 2-((2-(4-methoxybenzylidene)-1-phenylhydrazinyl)methyl)pyridine, L2H = N,N-dimethyl-4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazono)methyl)aniline, L3H = N,N-diethyl-4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazono)methyl) aniline and L4H = 4-(4-((2-phenyl-2-(pyridin-2-ylmethyl)hydrazono) methyl)phenyl)morpholine H = dissociable proton). Molecular structure of catalysts (C1–C4) were further established by single X-ray crystallographic studies. The catalytic performance of palladacycles (C1–C4) was explored with the direct Csp2–H arylation of imidazoles with aryl halide derivatives. These palladacycles were also applied for investigating of Mizoroki–Heck reactions with aryl halides and acrylate derivatives. During catalytic cycle in situ generated Pd(0) nanoparticles were characterized by XPS, SEM and TEM analysis and possible reaction pathways were proposed. The catalyst was employed as a pre-catalyst for the gram-scale synthesis of octinoxate, which is utilized as a UV-B sunscreen agent.
Maji, Ankur,Singh, Ovender,Singh, Sain,Mohanty, Aurobinda,Maji, Pradip K.,Ghosh, Kaushik
p. 1596 - 1611
(2020/04/29)

Cobalt catalyzed stereodivergent semi-hydrogenation of alkynes using H2O as the hydrogen source
Cobalt-catalyzed stereodivergent semi-hydrogenation of internal alkynes to alkenes is developed. The reaction proceeded through transfer hydrogenation under mild conditions using a base metal CoI2 as the catalyst, and H2O/MeOH as the hydrogen source with Zn as the reductant. The E/Z-selectivity of the product could be switched by changing the solvent and by inclusion/exclusion of a bidentate phosphine ligand (dppe). This method provides a simple and cost effective pathway for the synthesis of 1,2-dideuterioalkenes.
Li, Kangkui,Khan, Ruhima,Zhang, Xuexin,Gao, Yang,Zhou, Yongyun,Tan, Heng,Chen, Jingchao,Fan, Baomin
p. 5663 - 5666
(2019/05/21)

Galloyl esters of trans-stilbenes are inhibitors of FASN with anticancer activity on non-small cell lung cancer cells
Fatty acid synthase (FASN) is a lipogenic enzyme that is selectively upregulated in malignant cells. There is growing consensus on the oncogenicity of FASN-driven lipogenesis and the potential of FASN as a druggable target in cancer. Here, we report the synthesis and FASN inhibitory activities of two novel galloyl esters of trans-stilbene EC1 and EC5. Inhibition of FASN was accompanied by a loss in AKT activation and profound apoptosis in several non-small cell lung cancer (NSCLC) cells at the growth inhibitory concentrations of EC1 and EC5. Both FASN and phospho-AKT levels were concurrently downregulated. However, addition of a lipid concentrate to the treated cells reinstated cell viability and reversed the loss of FASN and AKT protein levels, thus recapitulating the causal relationship between FASN inhibition and the loss in cell viability.
Tan, Yu-Jia,Ali,Tee, Sheng-Yang,Teo, Jun-Ting,Xi, Yu,Go, Mei-Lin,Lam
(2019/08/20)

Iron-Catalyzed Nitrene Transfer Reaction of 4-Hydroxystilbenes with Aryl Azides: Synthesis of Imines via C=C Bond Cleavage
C=C bond breaking to access the C=N bond remains an underdeveloped area. A new protocol for C=C bond cleavage of alkenes under nonoxidative conditions to produce imines via an iron-catalyzed nitrene transfer reaction of 4-hydroxystilbenes with aryl azides is reported. The success of various sequential one-pot reactions reveals that the good compatibility of this method makes it very attractive for synthetic applications. On the basis of experimental observations, a plausible reaction mechanism is also proposed.
Peng, Yi,Fan, Yan-Hui,Li, Si-Yuan,Li, Bin,Xue, Jing,Deng, Qing-Hai
supporting information
p. 8389 - 8394
(2019/10/16)

Convenient and efficient Suzuki–Miyaura and Heck–Mizoroki cross-coupling reactions catalyzed by 1,3,4-trisubstituted-1,2,3-triazolium iodide and palladium salt systems
A series of 1,3,4-trisubstituted-1,2,3-triazolium iodide salts (4a–c) were synthesized via a three-step reaction sequence. Corresponding anilines (1a–c) were converted to azides (2a–c) which were then treated with phenylacetylene with “Click” chemistry to access 1,4-disubstituted-1,2,3-triazoles (3a–c). Subsequent methylation of 1,4-disubstituted-1,2,3-triazoles (3a–c) yielded 1,3,4-trisubstituted-1,2,3-triazoliumiodide salts (4a–c) in appreciable yields. All the synthesized compounds were characterized by 1H and 13C NMR, ATR–IR spectroscopic techniques and elemental analyses. Additionally, the structure of 1-(4-chlorophenyl)-4-phenyl-1,2,3-triazole (3b) was confirmed by single crystal X-ray diffraction analysis. The catalytic activity of 4a–c in a catalytic system consisting of 1,3,4-trisubstituted-1,2,3-triazoliumiodide salt/palladium(II) acetate/base were investigated toward Suzuki–Miyaura and Heck–Mizoroki cross-coupling reactions. The Suzuki–Miyaura cross-coupling reactions were carried out under mild reaction conditions with good to excellent yields, whereas Heck–Mizoroki cross-coupling reactions were performed at elevated temperature with moderate yields. Further, in situ method skips the synthetic procedure of preparing the palladium(II) complexes and hence is more economical and less tedious. (Figure presented.).
Shahini,Achar, Gautam,Budagumpi, Srinivasa,Dateer, Ramesh B.,Müller-Bunz, Helge,Tacke, Matthias,Patil, Siddappa A.
p. 528 - 549
(2019/02/26)

Novel Hybrid Conjugates with Dual Suppression of Estrogenic and Inflammatory Activities Display Significantly Improved Potency against Breast Cancer
In this work, we developed a small library of novel OBHS-RES hybrid compounds with dual inhibition activities targeting both the estrogen receptor α (ERα) and NF-?B by incorporating resveratrol (RES), a known inhibitor of NF-?B, into a privileged indirect antagonism structural motif (OBHS, oxabicycloheptene sulfonate) of estrogen receptor (ER). The OBHS-RES conjugates could bind well to ER and showed remarkable ERα antagonistic activity, and they also exhibited excellent NO inhibition in macrophage RAW 264.7 cells. Compared with 4-hydroxytamoxifen, some of them showed better antiproliferative efficacy in MCF-7 cell lines with IC50 up to 3.7 μM. In vivo experiments in a MCF-7 breast cancer model in Balb/c nude mice indicated that compound 26a was more potent than tamoxifen. Exploration of the compliancy of the structure against ER specificity utilizing these types of isomeric three-dimensional ligands indicated that one enantiomer had much better biological activity than the other.
Ning, Wentao,Hu, Zhiye,Tang, Chu,Yang, Lu,Zhang, Silong,Dong, Chune,Huang, Jian,Zhou, Hai-Bing
supporting information
p. 8155 - 8173
(2018/08/09)

Synthesis, characterization and evaluation of gemfibrozil-stilbene hybrid as antioxidant agent
Background: Oxidative stress and inflammation are important processes involved in cardiovascular disease. Antioxidant agents, like drugs or natural products from plants or plant-based food, represent a promising approach to treat these pathologies. Methods: In light of this, a gemfibrozil-stilbene hybrid (GEM-STIL) was synthesized as a strategy to combine the well-known antioxidant activity of stilbenes with the reported antioxidant and anti-inflammatory actions of fibrates such as gemfibrozil. The physicochemical properties, including aqueous solubility, partition coefficient, chemical stability and enzymatic hydrolysis of GEM-STIL have been studied and indicated that it is stable and has a good lipophilicity. The biological activity was also evaluated for its effect on C2C12 cell line viability and antioxidant activities. Results: The results indicated that GEM-STIL was well tolerated and induced a reduction of cell viability only at higher concentration (100 μg/ml). On the other hand, also at lower nontoxic concentrations (5, 25 and 50 μg/ml) exhibited a significant reduction of ROS production as well as a protective effect against the induced oxidative stimulus. Conclusion: These findings suggest that GEM-STIL is a potential new antioxidant agent useful in oxidative stress-related pathologies.
Amoroso, Rosa,Leporini, Lidia,Cacciatore, Ivana,Marinelli, Lisa,Ammazzalorso, Alessandra,Bruno, Isabella,De Filippis, Barbara,Fantacuzzi, Marialuigia,Maccallini, Cristina,Menghini, Luigi,Di Stefano, Antonio,Giampietro, Letizia
p. 1230 - 1238
(2018/11/01)

Transition-Metal-Free Highly Chemoselective and Stereoselective Reduction with Se/DMF/H2O System
A novel metal-free reduction system, in which H2Se (or HSe-) produced in situ from Se/DMF/H2O acts as the active reducing species, has been developed. By using water as an inexpensive, safe, and environmentally friendly surrogate as the hydrogen donor, this new reduction system incorporating Se/DMF/H2O displayed high selectivity and good activity in the reduction of α,β-unsaturated ketones and alkynes. Therefore, this reduction system has great potential to be a general and practical reduction methodology in organic transformation.
Li, Hong-Chen,An, Cui,Wu, Ge,Li, Guo-Xing,Huang, Xiao-Bo,Gao, Wen-Xia,Ding, Jin-Chang,Zhou, Yun-Bing,Liu, Miao-Chang,Wu, Hua-Yue
supporting information
p. 5573 - 5577
(2018/09/12)

Selective synthesis of the resveratrol analogue 4,4′-dihydroxy-: Trans -stilbene and stilbenoids modification by fungal peroxygenases
This work gives first evidence that the unspecific peroxygenases (UPOs) from the basidiomycetes Agrocybe aegerita (AaeUPO), Coprinopsis cinerea (rCciUPO) and Marasmius rotula (MroUPO) are able to catalyze the regioselective hydroxylation of trans-stilbene to 4,4′-dihydroxy-trans-stilbene (DHS), a resveratrol (RSV) analogue whose preventive effects on cancer invasion and metastasis have very recently been shown. Nearly complete transformation of substrate (yielding DHS) was achieved with the three enzymes tested, using H2O2 as the only co-substrate, with AaeUPO showing exceptionally higher total turnover number (200000) than MroUPO (26000) and rCciUPO (1400). Kinetic studies demonstrated that AaeUPO was the most efficient enzyme catalyzing stilbene dihydroxylation with catalytic efficiencies (kcat/Km) one and two orders of magnitude higher than those of MroUPO and rCciUPO, so that 4-hydroxystilbene appears to be the best UPO substrate reported to date. In contrast, the peroxygenase from the ascomycete Chaetomium globosum (CglUPO) failed to hydroxylate trans-stilbene at the aromatic ring and instead produced the trans-epoxide in the alkenyl moiety. In addition, stilbenoids such as pinosylvin (Pin) and RSV were tested as substrates for the enzymatic synthesis of RSV from Pin and oxyresveratrol (oxyRSV) from both RSV and Pin. Overall, lower conversion rates and regioselectivities compared with trans-stilbene were accomplished by three of the UPOs, and no conversion was observed with CglUPO. The highest amount of RSV (63% of products) and oxyRSV (78%) were again attained with AaeUPO. True peroxygenase activity was demonstrated by incorporation of 18O from H218O2 into the stilbene hydroxylation products. Differences in the number of phenylalanine residues at the heme access channels seems related to differences in aromatic hydroxylation activity, since they would facilitate substrate positioning by aromatic-aromatic interactions. The only ascomycete UPO tested (that of C. globosum) turned out to have the most differing active site (distal side of heme cavity) and reactivity with stilbenes resulting in ethenyl epoxidation instead of aromatic hydroxylation. The above oxyfunctionalizations by fungal UPOs represent a novel and simple alternative to chemical synthesis for the production of DHS, RSV and oxyRSV.
Aranda, Carmen,Ullrich, René,Kiebist, Jan,Scheibner, Katrin,Del Río, José C.,Hofrichter, Martin,Martínez, Angel T.,Gutiérrez, Ana
p. 2394 - 2401
(2018/05/23)

Palladium-Catalyzed Reductive Coupling Reaction of Terminal Alkynes with Aryl Iodides Utilizing Hafnocene Difluoride as a Hafnium Hydride Precursor Leading to trans-Alkenes
Herein, we describe a reductive cross-coupling of alkynes and aryl iodides by using a novel catalytic system composed of a catalytic amount of palladium dichloride and a promoter precursor, hafnocene difluoride (Cp2HfF2, Cp=cyclopentadienyl anion), in the presence of a mild reducing reagent, a hydrosilane, leading to a one-pot preparation of trans-alkenes. In this process, a series of coupling reactions efficiently proceeds through the following three steps: (i) an initial formation of hafnocene hydride from hafnocene difluoride and the hydrosilane, (ii) a subsequent hydrohafnation toward alkynes, and (iii) a final transmetalation of the alkenyl hafnium species to a palladium complex. This reductive coupling could be chemoselectively applied to the preparation of trans-alkenes with various functional groups, such as an alkyl group, a halogen, an ester, a nitro group, a heterocycle, a boronic ester, and an internal alkyne.
Takahashi, Keita,Ogiwara, Yohei,Sakai, Norio
supporting information
p. 809 - 814
(2018/03/13)

Pd(OAc)2 immobilized on imine-functionalized microporous covalent triazine polymer as efficient heterogeneous catalyst for Mizoroki–Heck cross-coupling reaction
A template consisting of Pd(OAc)2 immobilized on imine-functionalized microporous covalent triazine polymer network (Pd/TATAE) was synthesized and found to be an efficient and recyclable heterogeneous solid catalyst for Mizoroki–Heck C–C coupling of styrene with substituted aryl halides under mild reaction conditions and without addition of any ligand or additives. Furthermore, Pd/TATAE could be recycled for nine consecutive cycles with minor loss of catalytic activity. Finally, the Pd/TATAE catalyst showed good catalytic activity with excellent yield of 96?% and high turnover number of 3349.
Sadhasivam, Velu,Mathappan, Mariyappan,Harikrishnan, Muniyasamy,Chithiraikumar, Chinnadurai,Murugesan, Sepperumal,Siva, Ayyanar
p. 2853 - 2866
(2018/02/16)

Chemo-enzymatic synthesis of (: E)-2,3-diaryl-5-styryl- trans -2,3-dihydrobenzofuran-based scaffolds and their in vitro and in silico evaluation as a novel sub-family of potential allosteric modulators of the 90 kDa heat shock protein (Hsp90)
Herein we propose a facile, versatile and selective chemo-enzymatic synthesis of substituted (E)-2,3-diaryl-5-styryl-trans-2,3-dihydrobenzofurans based on the exploitation of the laccase-mediated oxidative (homo)coupling of (E)-4-styrylphenols. Thanks to this novel synthetic strategy, a library of benzofuran-based potential allosteric activators of the Heat shock protein 90 (Hsp90) was easily prepared. Moreover, considering their structural analogies to previously reported allosteric modulators, the sixteen new compounds synthesized in this work were tested in vitro for their potential stimulatory action on the ATPase activity of the molecular chaperone Hsp90. Combining experimental and computational results, we propose a mechanism of action for these compounds, and expand the structure-activity relationship (SAR) information available for benzofuran-based Hsp90 activators.
Bassanini, Ivan,D'Annessa, Ilda,Costa, Massimo,Monti, Daniela,Colombo, Giorgio,Riva, Sergio
p. 3741 - 3753
(2018/05/31)

Enhanced photocatalytic activity of gold nanoparticles driven by supramolecular host-guest chemistry
Functionalization of gold nanoparticles with supramolecular hosts allows their plasmon-based photocatalytic activity to be enhanced. This is mainly ascribed to the formation of labile host-guest complexes with the reagent molecules on the metal surface, thus promoting nanoparticle-substrate approximation without interfering with the light-induced catalytic process.
Padilla, Marc,Peccati, Francesca,Bourdelande, José Luis,Solans-Monfort, Xavier,Guirado, Gonzalo,Sodupe, Mariona,Hernando, Jordi
supporting information
p. 2126 - 2129
(2017/02/19)

Regioselective Hydroxylation of Stilbenes by Engineered Cytochrome P450 from Thermobifida fusca YX
Since the past decades, the plant stilbenoid resveratrol has gained significant attention of the general public as well as the research community due to its versatile medicinal properties. Apart from resveratrol, there is also an increasing interest in other plant stilbenoids because of their different potential biological activities. In order to meet the increasing demand for stilbenoids, alternative and sustainable approaches for their production are needed. We identified the cytochrome P450 monooxygenase 154E1 from Thermobifida fusca YX (CYP154E1) which enables the synthesis of (E)-4,4′-dihydroxystilbene via direct double hydroxylation of (E)-stilbene. The construction of a triple mutant led to a more than six-fold increased catalytic efficiency compared to the wild type enzyme. CYP154E1 and variants thereof accepted not only (E)-stilbene but also possessed remarkable activity towards ortho- and meta-substituted hydroxystilbenes leading to resveratrol, (E)-2,4′-dihydroxystilbene, (E)-2,4′,5-trihydroxystilbene and (E)-3,4′-dihydroxystilbene. The combination of protein engineering and the use of methyl-β-cyclodextrin as substrate solubilizing agent resulted in product titers of up to 4.2 g L?1 and enzyme total turnover numbers (TTN) of up to 20,000. (Figure presented.).
Rühlmann, Ansgar,Antovic, Dragutin,Müller, Thomas J. J.,Urlacher, Vlada B.
p. 984 - 994
(2017/03/27)

Pd/Indanone-Based Ligands: An Efficient Catalyst System for Ullmann-Type, Suzuki-Miyaura, and Mizoroki-Heck Cross-Coupling Reactions with Aryl Tosylates and Aryl Halides
2-Hydroxyindan-1-ones have been efficiently synthesized and successfully applied as ligands in Pd-catalyzed Ullmann type, Suzuki-Miyaura, and Mizoroki-Heck cross-coupling reactions with aryl tosylates and aryl halides. The ligands are air- and moisture-stable and have shown high catalytic activity with Pd(OAc) 2 in these cross-coupling reactions. The system tolerates a variety of functional groups in the product and can be re-used at least three times with maximum efficiency..
Waheed, Mohammed,Ahmed, Naseem
p. 4372 - 4382
(2017/09/12)

MizorokiHeck cross-coupling reaction of haloarenes mediated by a well-controlled modified polyacrylamide brush grafted silica/pd nanoparticle system
Modified polyacrylamide brushes including phosphinite functionality grafted onto silica supported Pd nanoparticles were synthesized via RAFT polymerization technique in a controlled manner with elucidated graft density and chain length. Proper activity of the catalyst was indicated in the MizorokiHeck coupling reaction of various haloarenes with olefins. Different aryl iodides with electron rich and electron deficient substituent and also ortho and heterocyclic substrate showed good reactivity to generate the corresponding coupled products in good to excellent yields using low Pd loading. The turnover number (TON) for this catalyst can be reduced up to 9.5×103. Simple filtration, appropriate reusability and negligible palladium leaching of this catalyst are among other advantages.
Ghasemi, Soheila,Karim, Saiede
p. 485 - 490
(2017/06/19)

A genomic DNA reporter screen identifies squalene synthase inhibitors that act cooperatively with statins to upregulate the low-density lipoprotein receptor
Hypercholesterolemia remains one of the leading risk factors for the development of cardiovascular disease. Many large double-blind studies have demonstrated that lowering low-density lipoprotein (LDL) cholesterol using a statin can reduce the risk of having a cardiovascular event by approximately 30%. However, despite the success of statins, some patient populations are unable to lower their LDL cholesterol to meet the targeted lipid levels, due to compliance or potency issues. This is especially true for patients with heterozygous familial hypercholesterolemia who may require additional upregulation of the low-density lipoprotein receptor (LDLR) to reduce LDL cholesterol levels below those achievable with maximal dosing of statins. Here we identify a series of small molecules from a genomic DNA reporter screen that upregulate the LDLR in mouse and human liver cell lines at nanomolar potencies (EC50 = 39 nM). Structure-activity relationship studies carried out on the lead compound, OX03771 [(E)-N,N-dimethyl-3-(4-styrylphenoxy)propan-1-amine], led to the identification of compound OX03050 [(E)-3-(4-styrylphenoxy)propan-1-ol], which had similar potency (EC50 = 26 nM) but a much-improved pharmacokinetic profile and showed in vivo efficacy. Compounds OX03050 and OX03771 were found to inhibit squalene synthase, the first committed step in cholesterol biosynthesis. These squalene synthase inhibitors were shown to act cooperatively with statins to increase LDLR expression in vitro. Overall, we demonstrated here a novel series of small molecules with the potential to be further developed to treat patients either alone or in combination with statins.
Kerr, Alastair G.,Tam, Lawrence C.S.,Hale, Ashley B.,Cioroch, Milena,Douglas, Gillian,Agkatsev, Sarina,Hibbitt, Olivia,Mason, Joseph,Holt-Martyn, James,Bataille, Carole J.R.,Wynne, Graham M.,Channon, Keith M.,Russell, Angela J.,Wade-Martins, Richard
supporting information
p. 417 - 428
(2017/05/25)

An effective Pd nanocatalyst in aqueous media: Stilbene synthesis by Mizoroki-Heck coupling reaction under microwave irradiation
Aqueous Mizoroki-Heck coupling reactions under microwave irradiation (MW) were carried out with a colloidal Pd nanocatalyst stabilized with poly(N-vinylpyrrolidone) (PVP). Many stilbenes and novel heterostilbenes were achieved in good to excellent yields starting from aryl bromides and different olefins. The reaction was carried out in a short reaction time and with low catalyst loading, leading to high turnover frequency (TOFs of the order of 100 h-1). The advantages like operational simplicity, high robustness, efficiency and turnover frequency, the utilization of aqueous media and simple product work-up make this protocol a great option for stilbene syntheses by Mizoroki-Heck reaction.
García, Carolina S.,Uberman, Paula M.,Martín, Sandra E.
p. 1717 - 1727
(2017/09/27)

An efficient Pd-NHC catalyst system in situ generated from Na2PdCl4 and PEG-functionalized imidazolium salts for Mizoroki-Heck reactions in water
Three PEG-functionalized imidazolium salts L1-L3 were designed and prepared from commercially available materials via a simple method. Their corresponding water soluble Pd-NHC catalysts, in situ generated from the imidazolium salts L1-L3 and Na2PdCl4 in water, showed impressive catalytic activity for aqueous Mizoroki-Heck reactions. The kinetic study revealed that the Pd catalyst derived from the imidazolium salt L1, bearing a pyridine-2-methyl substituent at the N3 atom of the imidazole ring, showed the best catalytic activity. Under the optimal conditions, a wide range of substituted alkenes were achieved in good to excellent yields from various aryl bromides and alkenes with the catalyst TON of up to 10,000.
Sun, Nan,Chen, Meng,Jin, Liqun,Zhao, Wei,Hu, Baoxiang,Shen, Zhenlu,Hu, Xinquan
supporting information
p. 1735 - 1744
(2017/09/27)

Tetrahydropyrrolization of Resveratrol and Other Stilbenes Improves Inhibitory Effects on DNA Oxidation
The inhibitory effect of resveratrol on DNA oxidation caused by 2,2′-azobis(2-amidinopropane hydrochloride) (AAPH) was found to be enhanced if the C=C bond in resveratrol was converted into tetrahydropyrrole by reaction with azomethine ylide (CH2=N+(CH3)CH2?). This encouraged us to explore whether the inhibitory activities of other stilbenes could also be increased by the same method. We found that the inhibitory effects of the tetrahydropyrrole derivatives on AAPH-induced oxidation of DNA were higher than those of the corresponding stilbenes, because the tetrahydropyrrole motif can provide hydrogen atoms to be abstracted by radicals. Therefore, the tetrahydropyrrolization offered an advantage for enhancing the antioxidant effects of stilbenes. Notably, (CH3)3SiCH2N(CH3)CH2OCH3(in the presence of CF3COOH) and (CH3)3NO (in the presence of LiN(iPr)2) can be used to generate azomethine ylide for the tetrahydropyrrolization of stilbenes containing electron-withdrawing and -donating groups, respectively.
Bao, Liang-Liang,Liu, Zai-Qun
p. 1617 - 1625
(2016/08/28)

Synthesis and tyrosinase inhibition activity of trans-stilbene derivatives
Synthesis of a focussed library of trans-stilbene compounds through Wittig and other base catalysed condensation reactions is presented. The synthesized stilbenes were screened for their inhibitory potential against murine tyrosinase activity to explore the structure activity relationship (SAR). Presence of electron withdrawing group (-CN) at the double bond and hydroxyl group or halogen atom especially at para-position on the aromatic rings was found to significantly elevate the inhibitory activity. Among all the compounds screened, compounds 2, 6, 8, 10, 11, 15 and 21 were found to exhibit appreciable inhibitory activity. Compound 21 ((E)-2,3-bis(4-Hydroxyphenyl)acryonitrile) was found to be the most active with an IC50 value of 5.06 μM which is less than half of the value 10.78 μM observed for resveratrol (common standard used in murine tyrosinase activity studies) under similar conditions. The results obtained from the present study reveal structural/functional group sensitivity for the tyrosinase inhibitory activity of stilbenoid moieties and are expected to be very helpful for the design and synthesis of novel, selective and effective tyrosinase inhibitors.
Ismail, Tabasum,Shafi, Syed,Srinivas, Jada,Sarkar, Dhiman,Qurishi, Yasrib,Khazir, Jabeena,Alam, Mohammad Sarwar,Kumar, Halmuthur Mahabalarao Sampath
p. 97 - 102
(2016/01/25)

Direct trans-Selective Ruthenium-Catalyzed Reduction of Alkynes in Two-Chamber Reactors and Continuous Flow
An efficient trans-selective hydrogenation of alkynes under low hydrogen pressure and low reaction temperatures is reported, applying a commercially available ruthenium hydride complex. The developed reaction conditions, which tolerate a variety of functional groups, are carried out in a two-chamber setup with ex situ generated hydrogen. The reaction setup is highly suitable for deuterium labeling. The trans-selective hydrogenation was extrapolated to a transfer hydrogenation protocol, employing a packed bed immobilized ruthenium hydride catalyst in continuous flow with a retention time of only 10 min.
Neumann, Karoline T.,Klimczyk, Sebastian,Burhardt, Mia N.,Bang-Andersen, Benny,Skrydstrup, Troels,Lindhardt, Anders T.
p. 4710 - 4714
(2016/07/12)

Coumarin based novel ligands in the Suzuki–Miyaura and Mizoroki–Heck cross-couplings under aqueous medium
Coumarin-based novel ligands (benzylidine-bis-(4-hydroxycoumarin)-diethylamines) were easily synthesized using 4-hydroxycoumarin, aromatic aldehydes, and diethylamine. The ionic ligand structure was established by X-ray study. They are air and moisture stable ligands and have shown highly efficient catalytic activity with Pd(OAc)2(0.1 mol % loading) in the Suzuki–Miyaura and (0.3 mol % loading) in the Mizoroki–Heck cross-coupling reactions in water or water/ethanol mixture. Pd-catalyst was reused efficiently without affecting variety of functional groups in the reaction.
Waheed, Mohammed,Ahmed, Naseem
supporting information
p. 3785 - 3789
(2016/07/26)

SQUALENE COMPOUNDS AS MODULATORS OF LDL-RECEPTOR EXPRESSION
The present invention relates to compounds that modify low density lipoprotein receptor (LDLR) expression. The compounds have the structural formula I shown below: wherein m, R1, n, R2 and R3 are each as defined herein. The present invention also relates to processes for the preparation of these compounds, to pharmaceutical compositions comprising them, and to their use in the treatment of diseases or disorders associated with elevated levels of low density lipoprotein cholesterol (LDL-C).
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Paragraph 0003; 0038

(2016/04/20)

Cyclodextrin-Grafted Silica-Supported Pd Nanoparticles: An Efficient and Versatile Catalyst for Ligand-Free C-C Coupling and Hydrogenation
Silica is an extremely versatile support, which is capable of hosting metal nanoparticles (NPs) and enhancing their stability and reactivity. In this study, a novel cyclodextrin/silica support for Pd NPs, which we have denoted Pd/Si-CD, has been prepared. The highly efficient and homogeneous impregnation of small palladium nanoparticles on this support has been carried out under conventional conditions, and ultrasound irradiation has been shown to have a beneficial effect on catalyst preparation. The catalyst exhibited excellent activity in ligand-free C-C Suzuki and Heck couplings with a large number of aryl iodide and bromides, in which microwave irradiation use cuts down reaction time. Pd/Si-CD have shown high activity and selectivity in the hydrogenation reaction, and the semihydrogenation of phenyl acetylene was also studied with excellent results.
Martina, Katia,Baricco, Francesca,Caporaso, Marina,Berlier, Gloria,Cravotto, Giancarlo
p. 1176 - 1184
(2016/04/05)

Ligand Control of E/Z Selectivity in Nickel-Catalyzed Transfer Hydrogenative Alkyne Semireduction
A nickel-catalyzed transfer hydrogenative alkyne semireduction protocol that can be applied to both internal and terminal alkynes using formic acid and Zn as the terminal reductants has been developed. In the case of internal alkynes, the (E)- or (Z)-olefin isomer can be accessed selectively under the same reaction conditions by judicious inclusion of a triphos ligand.
Richmond, Edward,Moran, Joseph
p. 6922 - 6929
(2015/10/05)

THERAPEUTIC AGENTS FOR SKIN DISEASES AND CONDITIONS
The present invention relates to method(s) of treating a subject afflicted with a skin disease or condition, the method comprising administering to the subject or patient in need a composition comprising a therapeutically effective amount of a substituted cis or trans- stilbene or a stilbene hybrid. A method of treating or reducing the likelihood of a skin disease or condition in a patient is an additional embodiment of the present invention. Preferred pharmaceutical compositions of the invention include nanoemulsions comprising a therapeutically effective amount of a substituted cis or trans-stilbene or stilbene hybrid and at least one antibiotic.
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(2015/06/18)

Heck Reactions Catalyzed by Ultrasmall and Uniform Pd Nanoparticles Supported on Polyaniline
Using air as the oxidant instead of the traditionally employed persulfates, the smaller and more uniform Pd nanoparticles (around 2 nm) supported on polyaniline (Pd@PANI) can be easily fabricated by the oxidation-polymerization of aniline with PdCl2. This material is an efficient and environmentally friendly catalyst for Heck reactions due to its recyclability, low loading, and ligand-free and mild reaction conditions. It was even tolerant to sulfur-containing substrates. This work reports the Pd@PANI-catalyzed Heck reactions with very wide substrate scopes, and discloses the catalytic mechanisms based on experimental findings and results of catalyst analysis and characterization.
Yu, Lei,Huang, Yaping,Wei, Zheng,Ding, Yuanhua,Su, Chenliang,Xu, Qing
p. 8677 - 8683
(2015/09/15)

Polystyrene resin supported palladium(0) (Pd@PR) nanocomposite catalyzed synthesis of β-aryl and β,β-diaryl unsaturated scaffolds following tandem approaches
A one pot general tandem procedure is described for β-aryl and β,β-diaryl alkenes synthesis following an alternative to the classical approaches by using aryl aldehyde as one of the starting materials. The developed polystyrene resin supported palladium(0) (Pd@PR) nanocomposite has been applied in an unprecedented sequential condensation-decarboxylation-Heck (CDH) and condensation-Heck (CH) strategies to generate the substituted alkenes (C6(C6)CC-C, C6-CC-C6, and C6(C6)CC-CO-C6 units) under ligand, and additive free milder basic reaction conditions. The added momentous benefit over the classical methodologies is in terms of its multi-component approach to achieve the desired products without tedious step wise purifications. This journal is
Shil, Arun K.,Das, Pralay
p. 24859 - 24863
(2015/03/30)

Novel glycosyl pyridyl-triazole@palladium nanoparticles: Efficient and recoverable catalysts for C-C cross-coupling reactions
We report the development of a series of glycosyl pyridyl-triazole@palladium nanoparticles (GPT-Pd) which were synthesized by the reaction of azidoglycosides with 2-ethynylpyridine via click chemistry. These palladium nanoparticles were obtained in high yields and were fully characterized by 1H and 13C NMR, elemental analysis, transmission electron microscopy, and thermogravimetric analysis. The single crystal structure of GPT-Pd catalyst 5c was determined to show that the glycosyl pyridyl-triazole coordinated with palladium in a bidentate (N,N) coordination mode. Their use in palladium-catalyzed C-C coupling reactions such as Suzuki-Miyaura coupling, Heck reaction and Sonogashira reaction achieved quantitative production under mild conditions. Furthermore, the catalysts can be easily separated from the reaction mixture and the catalytic activity remained unchanged even after 8 successive catalytic cycles. This journal is
Shen, Hongyun,Shen, Chao,Chen, Chao,Wang, Anming,Zhang, Pengfei
p. 2065 - 2071
(2015/04/14)

A novel D-glucosamine-derived pyridyltriazole@ palladium catalyst for solvent-free Mizoroki-Heck reactions and its application in the synthesis of Axitinib
A green method for the synthesis of a D-glucosamine-derived triazole@ palladium catalyst is described. The synthesized catalyst containing a 2-pyridyl-1,2,3-triazole ligand was prepared via a click route in high yields and was explored in Heck cross-coupling reactions between different aryl halides and olefins under solventfree conditions. The catalyst can be separated from the reaction mixture and reused at least six times with superior activity. In addition, using this protocol, the marketed drug Axitinib (antitumor) could be synthesized easily.
Shen, Chao,Shen, Hongyun,Yang, Ming,Xia, Chengcai,Zhang, Pengfei
supporting information
p. 225 - 230
(2018/04/16)

Copper-catalyzed Z-selective semihydrogenation of alkynes with hydrosilane: A convenient approach to cis-alkenes
A copper catalyst generated in situ from widely available copper salt and imidazolium salt in the presence of t-BuOK showed high efficiency for the semihydrogenation of a wide range of internal and terminal alkynes to their corresponding alkenes without obvious over-reduction. Functional groups, such as hydroxyl, nitro, halides, and amino, etc. were tolerated. The Z/E ratios of the obtained alkenes were generally >99%. Finally, semireduction of bulky alkynes also went smoothly.
Wang, Guang-Hui,Bin, Huai-Yu,Sun, Miao,Chen, Shu-Wei,Liu, Ji-Hong,Zhong, Chong-Min
supporting information
p. 2175 - 2179
(2014/03/21)

Chemically-induced geometrical isomerization of stilbenes during peroxyoxalate chemiluminescence reaction: Revisit to 'photochemistry without light'
The chemically-induced isomerization of stilbenes during the peroxyoxalate chemiluminescence (PO-CL) reactions was reinvestigated. The PO-CL reactions using bis(2,4,6-trichlorophenyl) oxalate in the presence of several stilbenes (type A reaction) produced cis-stilbenes in 0-4% yields, which was dependent on the singlet excitation energy of the stilbenes. On the other hand, the PO-CL reactions of the oxalates, containing the stilbene moieties in the molecules (type B reaction), produced cis-stilbenes 0-9.3% yields, some of which were much more effective than the type A reactions considering the amount of the oxalate moiety as the energy supplier.
Motoyoshiya, Jiro,Watanabe, Kanako,Takizawa, Airi,Shimizu, Hikaru,Maruyama, Takayuki
p. 619 - 622
(2014/01/23)

Synthesis and bioactivity of resveratrol analogues
It has been reported that resveratrol enhanced SIRT1 expression and significantly mimicked calorie restriction by stimulating Sir2 which is the most homologic homologue of SIRT1 of mammalian. A series of novel resveratrol derivatives were designed and synthesized as novel SIRT1 activator candidates. These synthesized compounds were characterized by spectral (1H NMR) analysis and examined for their Sir2 activation against yeast parental strain-BY4743 at a concentration of 100 μM/L by Bioscreen C MBR machine. Several compounds showed a promising Sir2 activation activity compared with resveratrol. Meanwhile, the structure-activity relationships with Sirt2 activation activities were also discussed.
Ao, Junli,Chen, Yuanmou,Xu, Xiaoling,Zhang, Xu,Yu, Yue,Yu, Peng,Hua, Erbing
p. 2092 - 2098
(2014/06/09)

Transition-metal-free semihydrogenation of diarylalkynes: Highly stereoselective synthesis of trans -alkenes using Na2S·9H 2O
A highly stereoselective and efficient transition-metal-free semihydrogenation of internal alkynes to E-alkenes using cheap and green water as hydrogen donor is described. The reactions are conducted under convenient conditions and provide products in good to excellent yields, with broad substrate scope, including a variety of diarylalkynes.
Chen, Zhengwang,Luo, Miaoting,Wen, Yuelu,Luo, Guotian,Liu, Liangxian
supporting information
p. 3020 - 3023
(2014/06/23)

Palladium/copper-catalyzed oxidative arylation of terminal alkenes with aroyl hydrazides
An unprecedented oxidative arylation reaction of terminal alkenes with simple aroyl hydrazides has been developed under aerobic conditions for the stereoselective synthesis of 1,2-disubstituted alkenes. A range of aroyl hydrazides underwent palladium/copper-catalyzed oxidative Mizoroki-Heck reaction with terminal alkenes open to air in a 1:1 mixture of dimethyl sulfoxide and acetonitrile to give structurally diverse 1,2-disubstituted alkenes in moderate to excellent yields with excellent regio- and E-selectivity. The reaction tolerated a wide variety of functional groups, such as alkoxy, hydroxy, amino, fluoro, chloro, bromo, cyano, nitro, ester, amide, imide, phosphine oxide, and sulfone groups, and, moreover, molecular oxygen and dimethyl sulfoxide were demonstrated to serve as terminal oxidants. This study provides a useful method for the stereoselective synthesis of 1,2-disubstituted alkenes through direct transformation of the vinylic Ci-H bonds in terminal alkenes. Cross-coupling: An oxidative arylation reaction of terminal alkenes with simple aroyl hydrazides has been developed in the presence of a PdCl2/CuI catalyst under aerobic conditions to give a range of structurally diverse 1,2-disubstituted alkenes in moderate to excellent yields with excellent regio- and E-selectivity (see scheme; r.s.=regioselectivity).
Zhang, Yong-Gang,Liu, Xiang-Lei,He, Zeng-Yang,Li, Xi-Ming,Kang, Hong-Jian,Tian, Shi-Kai
supporting information
p. 2765 - 2769
(2014/03/21)

Immobilized Pd complexes over HMMS as catalysts for Heck cross-coupling and selective hydrogenation reactions
High-performance Pd(0) on the surface of hollow magnetic mesoporous spheres (HMMS), with Fe3O4 nanoparticles embedded in the mesoporous shell was prepared. The catalyst was characterized by TEM, XRD, VSM and ICP. It showed high activity for selective hydrogenation of alkynes to alkenes and the Heck coupling reaction. The catalyst could be recovered in a facile manner from the reaction mixture and recycled six times without loss in activity.
Wang, Peng,Liu, Hengzhi,Liu, Mengmeng,Li, Rong,Ma, Jiantai
p. 1138 - 1143
(2014/03/21)

Synthesis and insect antifeedant activity of stilbene derivatives against Brontispa longissima Larvae
Continuing our search for natural product-based compounds for the control of B. longissima Larvae, 25 stilbene analogs were synthesized and evaluated for insect antifeedant activity against third-instar larvae of B. longissima for the first time. Among all the tested compounds, especially compounds 3a, 3c, and 6 showed pronounced antifeedant activities with AFC50 values of 0.218, 0.327, and 0.226 mg/mL, respectively. The different antifeedant activity ranges of these compounds indicated that variation of chemical structures in the stilbene skeleton markedly affected the activity profiles of this compound class, and some important SAR information has been revealed from it. In addition, to understand the structural requirements for antifeedant activities of the 25 synthesized stilbene analogs, a comparative molecular field analysis (CoMFA) model, which yielded the leave-one-out (LOO) cross-validated correlation coefficient (q 2) of 0.533 and a non-cross-validated correlation coefficient (r 2) of 0.929, was constructed. Together, these preliminary results may be useful in guiding further modification of stilbenes in the development of potential new antifeedants.
Liu, Ying-Qian,Li, Xiao-Jing,Zhao, Chun-Yan,Lu, Yan,Li, Wen-Qun,Liu, Zhen-Ling,Feng, Gang,Yang, Liu
p. 2196 - 2206
(2013/07/26)

The aminocyclodextrin/Pd(OAc)2 complex as an efficient catalyst for the Mizoroki-Heck cross-coupling reaction
An aminocyclodextrin/Pd(OAc)2 complex is used as an efficient, reusable catalyst in the Mizoroki-Heck reaction of aryl halides/triflates with olefins to give carbon-carbon-coupled products in good to excellent yields. This simple, efficient catalytic system is applicable to a wide range of aryl and heteroaryl halides/triflates and olefins. This environmentally benign procedure is less hazardous, milder, uses a catalytic amount of ligand and Pd(OAc) 2, avoids an inert atmosphere, and catalyst recovery and reusability are achieved. Copyright
Kanagaraj, Kuppusamy,Pitchumani, Kasi
supporting information
p. 14425 - 14431
(2013/11/06)

Scope and limitations of the Heck-Matsuda-coupling of phenol diazonium salts and styrenes: A protecting-group economic synthesis of phenolic stilbenes
4-Phenol diazonium salts undergo Pd-catalyzed Heck reactions with various styrenes to 4′-hydroxy stilbenes. In almost all cases higher yields and fewer side products were observed, compared to the analogous 4-methoxy benzene diazonium salts. In contrast, the reaction fails completely with 2- and 3-phenol diazonium salts. For these substitution patterns the methoxy-substituted derivatives are superior. The Royal Society of Chemistry 2013.
Schmidt, Bernd,Elizarov, Nelli,Berger, René,H?lter, Frank
p. 3674 - 3691
(2013/06/27)

Inhibition of VEGF expression in cancer cells and endothelial cell differentiation by synthetic stilbene derivatives
We here report the synthesis of several stilbene derivatives. They show a measurable inhibitory effect on angiogenesis, some of them to a higher degree than resveratrol. Test methods included cell proliferation and tube formation assays using bovine aorta endothelial cells. In addition, it has been confirmed through the reverse transcriptase/polymerase chain reaction experiment that these stilbene derivatives downregulate the expression of the gene related to the production of the angiogenesis factor VEGF in cancer cells.
Martí-Centelles, Rosa,Cejudo-Marín, Rocío,Falomir, Eva,Murga, Juan,Carda, Miguel,Alberto Marco
p. 3010 - 3015
(2013/07/05)

Mizoroki-Heck reactions catalyzed by palladium dichloro-bis(aminophosphine) complexes under mild reaction conditions. the importance of ligand composition on the catalytic activity
Dichloro-bis(aminophosphine) complexes of palladium with the general formula [(P{(NC5H10)3-n(C6H 11)n})2Pd(Cl)2] (where n = 0-2) are easily accessible, cheap and air stable, highly active and universally applicable C-C cross-coupling catalysts, which exhibit an excellent functional group tolerance. The ligand composition of amine-substituted phosphines (controlled by the number of P-N bonds) was found to effectively determine their catalytic activity in the Heck reaction, for which nanoparticles were demonstrated to be their catalytically active form. While dichloro{bis[1, 1′,1′′-(phosphinetriyl)tripiperidine]}palladium (1), the least stable complex (towards protons) within the series of [(P{(NC5H 10)3-n(C6H11)n}) 2Pd(Cl)2] (where n = 0-3), is a highly active Heck catalyst at 100 °C and, hence, a rare example of an effective and versatile Heck catalyst that efficiently operates under mild reaction conditions (100 °C or below), a significant successive drop in activity was noticed for dichloro-bis(1,1′-(cyclohexylphosphinediyl)dipiperidine)palladium (2, with n = 1), dichloro-bis(1-(dicyclohexylphosphinyl)piperidine)palladium (3, with n = 2) and dichloro-bis(tricyclohexylphosphine)palladium (4, with n = 3), of which the latter is essentially inactive (at least under the reaction conditions applied). This trend was explained by the successively increasing complex stability and its ensuing retarding effect on the (water-induced) generation of palladium nanoparticles thereof. This interpretation was experimentally confirmed (initial reductions of 1-4 into palladium(0) complexes of the type [Pd(P{(NC5H10)3-n(C6H 11)n})2] (where n = 0-3) were excluded to be the reason for the activity difference observed as well as molecular (Pd 0/PdII) mechanisms were excluded to be operative) and thus demonstrates that the catalytic activity of dichloro-bis(aminophosphine) complexes of palladium can-in reactions where nanoparticles are involved-effectively be controlled by the number of P-N bonds in the ligand system.
Oberholzer, Miriam,Frech, Christian M.
supporting information
p. 1678 - 1686
(2013/10/01)

The synthesis and photochromism of a 2,2-diaryl-6-styryl-2H-[1]benzopyran: Unexpected palladium-mediated ring-contraction of a 6-bromo-2,2-diaryl-2H-[1] benzopyran
The ligand-free Pd-mediated reaction between styrene and a 6-bromo-2,2-diaryl-2H-[1]benzopyran proceeded anomalously to give a 2-(diarylmethyl)-5-styrylbenzofuran via a tandem Heck coupling - ring-contraction process; none of the styryl substituted 2,2-diaryl-2H-[1] benzopyran was observed. A 2,2-diaryl-6-styryl-2H-[1]benzopyran resulted from the condensation between 4-hydroxystilbene and a 1,1-diarylpropynol and which exhibited photochromism through the reversible electrocyclisation of the pyran unit; no isomerisation - electrocyclisation of the stilbene moiety was detected.
Gabbutt, Christopher D.,Heron, B. Mark,Kilner, Colin,Kolla, Suresh B.
p. 825 - 830
(2012/07/01)

STILBENE ANALOGS AND METHODS OF TREATING CANCER
Stilbene analogs and pharmaceutical compositions that are useful for the treatment of various cancers, including without limitation, colorectal cancer (CRC) and breast cancer are disclosed. The halogenated stilbene analogs include nitrogen heteroaryl groups and/or amino groups on the stilbene ring.
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(2012/08/08)

Iron-catalyzed chemo- and stereoselective hydromagnesiation of diarylalkynes and diynes
Diarylalkynes are chemo- and stereoselectively hydromagnesiated in high yields at room temperature with an iron species generated in situ from FeCl 2and EtMgBr. Functional groups such as bromide, iodide, amine, phenoxide, and alkene are well tolerated. Under similar conditions, diynes are chemo-, regio-, and stereoselectively hydromagnesiated. The resulting alkenylmagnesium compounds are a platform for further functionalization as a one-pot reaction.
Ilies, Laurean,Yoshida, Takumi,Nakamura, Eiichi
supporting information
p. 16951 - 16954,4
(2020/09/02)

Syntheses of polyfunctionalized resveratrol derivatives using Wittig and Heck protocols
Improved protocols for Wittig reaction and palladium-catalyzed Heck coupling give expedient access to a series of unprecedented polyfunctionalized artificial-resveratrol derivatives. In the modified Wittig protocol, trimethylsilyl was used as a highly valuable protective group of the phenolic functions of starting aromatic materials. A clean O-alkylation of hydroxylated stilbenes with ethylene carbonate was also conducted. Thus, Wittig reaction followed by hydroxyethylation take place one-pot with only carbon dioxide as waste. Additionally, a palladium-catalyzed Heck coupling strategy was developed by using ferrocenyl phosphane ligands, and multi-functionalized hydroxylated stilbenes were obtained without the need of any protection/deprotection sequence. Up to six functional groups are introduced by these procedures, which limit the number of reactions steps, the waste toxicity, and the use of costly reagents.
Chalal, Malik,Vervandier-Fasseur, Dominique,Meunier, Philippe,Cattey, Hélène,Hierso, Jean-Cyrille
p. 3899 - 3907
(2012/07/14)