191867-92-2Relevant articles and documents
Palladium Complexes with Phenoxy- And Amidate-Functionalized N-Heterocyclic Carbene Ligands Based on 3-Phenylimidazo[1,5- a]pyridine: Synthesis and Catalytic Application in Mizoroki-Heck Coupling Reactions with Ortho-Substituted Aryl Chlorides
Hung, Cheng-Hau,Zheng, Wei-Yuan,Lee, Hon Man
, p. 702 - 713 (2021/04/02)
Mononuclear and tetranuclear palladium complexes with functionalized "abnormal"N-heterocyclic carbene (aNHC) ligands based on 3-phenylimidazo[1,5-a]pyridine were synthesized. All of the new complexes were structurally characterized by single-crystal X-ray diffraction studies. The new complexes were applied in the Mizoroki-Heck coupling reaction of aryl chlorides with alkenes in neat n-tetrabutylammonium bromide (TBAB). The mononuclear palladium complex with a tridentate phenoxy- and amidate-functionalized aNHC ligand displayed activity superior to that of the palladium complex with a bidentate amidate-functionalized aNHC ligand. The new tetranuclear complex with the tridentate ligand displayed the best activities, capable of the activation of deactivated aryl chlorides as substrates with a low Pd atom loading. Even challenging sterically demanding ortho-substituted aryl chlorides were successfully utilized as substrates. The studies revealed that the robustness of the catalyst precursor is crucial in delivering high catalytic activities. Also, the promising use of tetranuclear palladium complexes with functionalized aNHC ligands as the catalyst precursors in the Mizoroki-Heck coupling reaction in neat TBAB was demonstrated.
Mizoroki-Heck Cross-Coupling of Bromobenzenes with Styrenes: Another Example of Pd-Catalyzed Cross-Coupling with Potential Safety Hazards
Yang, Qiang,Sane, Neeraj,Klosowski, Daniel,Lee, Melissa,Rosenthal, Tay,Wang, Nick X.,Wiensch, Eric
, p. 2148 - 2156 (2019/11/02)
The potential safety hazards associated with the Mizoroki-Heck cross-coupling of bromobenzenes with styrenes were evaluated. The heat output from the reaction in various solvents was comparable in a variety of solvents; however, the rate of reaction was significantly faster in the presence of water. Thermal stability evaluation of the postreaction mixtures in DMSO and 3:1 DMSO/water by differential scanning calorimetry indicated that the onset temperatures of thermal decomposition were significantly lower than that of neat DMSO. Evaluation of the substrate scope revealed that the substitution pattern on the bromobenzene did not affect the heat output. The reaction rate of electron-deficient bromobenzenes was slower than that of the electron-rich bromobenzenes. In general, substituted styrenes afforded similar magnitudes of exotherms; however, the reaction rate of bromobenzene with 2-methylstyrene was significantly slower than the other studied styrenes. The predicted heat of reaction using the density functional theory method, B3LYP, was in good agreement with the experimental data. Such excellent agreement suggests that this calculation method can be used as a preliminary tool to predict heat of reaction and avoid exothermic reaction conditions. In many of the studied cases, the maximum temperature of a synthesis reaction was considerably higher than the solvent boiling point and thermal decomposition onset temperatures when the reaction was performed in DMSO or 3:1 DMSO/water. It is crucial to understand the thermal stability of the reaction mixture to design the process accordingly and ensure the reaction temperature is maintained below the onset temperature of decomposition to avoid potential runaway reactions.
Synthesis of 1,2-diarylethylenes by Pd-catalyzed one-pot reaction of benzyl halides, tosylhydrazide, and aryl aldehydes
Shen, Xu,Liu, Ping,Liu, Yan,Dai, Bin
, p. 709 - 715 (2018/07/14)
Background: Substituted olefins are versatile functional groups and intermediates in chemistry, medicine, electronics, and optics and materials science fields because of their unique properties. One important class of substituted olefins 1,2-diarylethylenes have attracted considerable attention due to their presence in both natural products and pharmacologically active substances. Methods: In this paper, we developed a one-pot two-step coupling reaction of aryl aldehydes, tosylhydrazide with benzyl halides by using inexpensive Pd(PPh3)4 as catalyst, leading to a variety of 1,2- diphenylethenes derivatives with moderate to good yields. Results: The desired 1,2-diarylethylenes were obtained in 46-96% yields via Pd(0)-catalyzed one-pot reaction of benzyl halides, tosylhydrazide, and aryl aldehydes. Conclusion: The catalytic system presented here enables the use of easily accessible starting materials and good functional group tolerance.
THERAPEUTIC AGENTS FOR SKIN DISEASES AND CONDITIONS
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Page/Page column 36; 48-49, (2015/06/18)
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.
Cobalt-catalyzed vinylation of aromatic halides using β-halostyrene: Experimental and DFT studies
Moncomble, Aurelien,Floch, Pascal Le,Lledos, Agusti,Gosmini, Corinne
experimental part, p. 5056 - 5062 (2012/07/14)
A new protocol for the direct cobalt-catalyzed vinylation of aryl halides using β-halostyrene has been developed in order to form functionalized stilbenes. A variety of aromatic halides featuring different reactive group were employed. This method proceeded smoothly with a total retention of the double bond configuration in the presence of triphenylphosphine as ligand. Preliminary DFT calculations rationnalize these results and proposed a reaction pathway in agreement with the experimental conditions. This procedure offers a new route to the stereoselective synthesis of stilbenes.
E-selective isomerization of stilbenes and stilbenoids through reversible hydroboration
Gray, Erin E.,Rabenold, Lake E.,Goess, Brian C.
experimental part, p. 6177 - 6179 (2011/12/01)
Hydroboration of a mixture of E and Z stilbenes and stilbenoids is followed by an elimination reaction to yield the E isomer with high stereoselectivity. The reaction tolerates aromatic substituents with varying stereoelectronic properties, occurs in one pot, and requires only commercially available reagents. An illustration of the isomerization reaction in a synthesis of resveratrol, a biologically active antioxidant, is presented.
Substituted CIS- and trans-stilbenes as therapeutic agents
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Page/Page column 20, (2010/11/28)
The present invention relates to method(s) of treating a subject afflicted with cancer or a precancerous condition, an inflammatory disease or condition, and/or stroke or other ischemic 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.
Low-valent niobium-mediated synthesis of indenes: Intramolecular coupling reaction of CF3 group with alkene C-H bond
Fuchibe, Kohei,Mitomi, Ken,Akiyama, Takahiko
, p. 24 - 25 (2007/10/03)
CF3 group of o-alkenyl-α,α,α-trifluorotoluenes underwent intramolecular coupling reaction with the alkene C-H bond under NbCl5/LiAlH4 system. Substituted indenes were obtained in good yields. Copyright
Substituted trans-stilbenes, including analogues of the natural product resveratrol, inhibit the human tumor necrosis factor alpha-induced activation of transcription factor nuclear factor kappaB
Heynekamp, Justin J.,Weber, Waylon M.,Hunsaker, Lucy A.,Gonzales, Amanda M.,Orlando, Robert A.,Deck, Lorraine M.,Vander Jagt, David L.
, p. 7182 - 7189 (2007/10/03)
The transcription factor nuclear factor kappaB (NF-κB), which regulates expression of numerous antiinflammatory genes as well as genes that promote development of the prosurvival, antiapoptotic state is up-regulated in many cancer cells. The natural product resveratrol, a polyphenolic trans-stilbene, has numerous biological activities and is a known inhibitor of activation of NF-κB, which may account for some of its biological activities. Resveratrol exhibits activity against a wide variety of cancer cells and has demonstrated activity as a cancer chemopreventive against all stages, i.e., initiation, promotion, and progression. The biological activities of resveratrol are often ascribed to its antioxidant activity. Both antioxidant activity and biological activities of analogues of resveratrol depend upon the number and location of the hydroxy groups. In the present study, phenolic analogues of resveratrol and a series of substituted trans-stilbenes without hydroxy groups were compared with resveratrol for their abilities to inhibit the human tumor necrosis factor alpha-induced (TNF-α) activation of NF-κB, using the Panomics NF-κB stable reporter cell line 293/NF-κB-luc. A series of 75 compounds was screened to identify substituted trans-stilbenes that were more active than resveratrol. Dose-response studies of the most active compounds were carried out to obtain IC50 values. Numerous compounds were identified that were more active than resveratrol, including compounds that were devoid of hydroxy groups and were 100-fold more potent than resveratrol. The substituted trans-stilbenes that were potent inhibitors of the activation of NFκB generally did not exhibit antioxidant activity. The results from screening were confirmed using BV-2 microglial cells where resveratrol and analogues were shown to inhibit LPS-induced COX-2 expression.
Functionalized ionic liquid as an efficient and recyclable reaction medium for phosphine-free palladium-catalyzed heck reaction
Zhou, Li,Wang, Lei
, p. 2653 - 2658 (2008/02/05)
A functionalized ionic liquid, 1-(2-hydroxyethyl)-3-methylimidazolium tetrafluoroborate ([HEmim][BF4]), was found to be as an efficient and recyclable reaction medium for palladium-catalyzed Heck reaction. The olefination of iodoarenes and bromoarenes with olefins generated the corresponding products in good to excellent yields under phosphine-free reaction conditions. The reaction involved the use of [HEmim][BF4] as the solvent, potassium phosphate as the base, and palladium acetate as the catalyst. In addition, palladium and ionic liquid could be recovered and recycled for six consecutive trials without significant loss of its reactivity. Georg Thieme Verlag Stuttgart.
