- Cobalt catalyzed stereodivergent semi-hydrogenation of alkynes using H2O as the hydrogen source
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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
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supporting information
p. 5663 - 5666
(2019/05/21)
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- Enhanced photocatalytic activity of gold nanoparticles driven by supramolecular host-guest chemistry
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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
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supporting information
p. 2126 - 2129
(2017/02/19)
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- Ligand Control of E/Z Selectivity in Nickel-Catalyzed Transfer Hydrogenative Alkyne Semireduction
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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
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p. 6922 - 6929
(2015/10/05)
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- Heck Reactions Catalyzed by Ultrasmall and Uniform Pd Nanoparticles Supported on Polyaniline
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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
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p. 8677 - 8683
(2015/09/15)
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- Copper-catalyzed Z-selective semihydrogenation of alkynes with hydrosilane: A convenient approach to cis-alkenes
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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
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supporting information
p. 2175 - 2179
(2014/03/21)
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- Chemically-induced geometrical isomerization of stilbenes during peroxyoxalate chemiluminescence reaction: Revisit to 'photochemistry without light'
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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
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p. 619 - 622
(2014/01/23)
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- Synthesis and insect antifeedant activity of stilbene derivatives against Brontispa longissima Larvae
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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
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p. 2196 - 2206
(2013/07/26)
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- Iron-catalyzed chemo- and stereoselective hydromagnesiation of diarylalkynes and diynes
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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
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supporting information
p. 16951 - 16954,4
(2020/09/02)
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- Syntheses of polyfunctionalized resveratrol derivatives using Wittig and Heck protocols
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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
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p. 3899 - 3907
(2012/07/14)
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- Stereodivergent ruthenium-catalyzed transfer semihydrogenation of diaryl alkynes
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[Ru3(CO)12]-catalyzed transfer semihydrogenation of various functionalized diaryl alkynes with N,N-dimethylformamide (DMF) and water as hydrogen source affords cis- and trans-stilbenes. The stereodivergent approach can be switched by the use of acetic (HOAc) or trifluoroacetic (TFA) acid as additives. The catalytic processes can be applied to the synthesis of analogues of natural products such as cis-combretastatin A-4 and trans-resveratrol. Copyright
- Li, Jie,Hua, Ruimao
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supporting information; experimental part
p. 8462 - 8465
(2011/08/07)
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- Highly selective semihydrogenation of phenylalkynes to (Z)-styrenes using hantzsch ester 1,4-dihydropyridine catalyzed by Pd/C
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Various alkynes have been selectively reduced to the corresponding Z-alkenes catalyzed by Pd/C using Hantzsch ester 1,4-dihydropyridine as the hydrogen source. Georg Thieme Verlag Stuttgart.
- Zhao, Yankai,Liu, Qiang,Li, Jing,Liu, Zhongquan,Zhou, Bo
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supporting information; experimental part
p. 1870 - 1872
(2010/10/04)
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- Reduction of solid-supported olefins and alkynes
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(Chemical Equation Presented) The reduction of carbon-carbonmultiple bonds in alkynes and olefins supported on a polystyrene resin has been investigated. Homogeneous catalysis by titanocene reagents is effective for the stereoselective preparation of cis-
- Dickson, David P.,Toh, Christine,Lunda, Menaka,Yermolina, Maria V.,Wardrop, Duncan J.,Landrie, Chad L.
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supporting information; experimental part
p. 9535 - 9538
(2010/03/04)
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- Design, synthesis, and structure - Activity relationships of alkylcarbamic acid aryl esters, a new class of fatty acid amide hydrolase inhibitors
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Fatty acid amide hydrolase (FAAH), an intracellular serine hydrolase enzyme, participates in the deactivation of fatty acid ethanolamides such as the endogenous cannabinoid anandamide, the intestinal satiety factor oleoylethanolamide, and the peripheral analgesic and anti-inflammatory factor palmitoylethanolamide. In the present study, we report on the design, synthesis, and structure-activity relationships (SAR) of a novel class of potent, selective, and systemically active inhibitors of FAAH activity, which we have recently shown to exert potent anxiolytic-like effects in rats. These compounds are characterized by a carbamic template substituted with alkyl or aryl groups at their O- and N-termini. Most compounds inhibit FAAH, but not several other serine hydrolases, with potencies that depend on the size and shape of the substituents. Initial SAR investigations suggested that the requirements for optimal potency are a lipophilic N-alkyl substituent (such as n-butyl or cyclohexyl) and a bent O-aryl substituent. Furthermore, the carbamic group is essential for activity. A 3D-QSAR analysis on the alkylcarbamic acid aryl esters showed that the size and shape of the O-aryl moiety are correlated with FAAH inhibitory potency. A CoMSIA model was constructed, indicating that whereas the steric occupation of an area corresponding to the meta position of an O-phenyl ring improves potency, a region of low steric tolerance on the enzyme active site exists corresponding to the para position of the same ring. The bent shape of the O-aryl moieties that best fit the enzyme surface closely resembles the folded conformations observed in the complexes of unsaturated fatty acids with different proteins. URB524 (N-cyclohexylcarbamic acid biphenyl-3-yl ester, 9g) is the most potent compound of the series (IC50 = 63 nM) and was therefore selected for further optimization.
- Tarzia, Giorgio,Duranti, Andrea,Tontini, Andrea,Piersanti, Giovanni,Mor, Marco,Rivara, Silvia,Plazzi, Pier Vincenzo,Park, Chris,Kathuria, Satish,Piomelli, Daniele
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p. 2352 - 2360
(2007/10/03)
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