19310-29-3Relevant articles and documents
Operation of the boomerang mechanism in olefin metathesis reactions promoted by the second-generation Hoveyda catalyst
Bates, Jennifer M.,Lummiss, Justin A. M.,Bailey, Gwendolyn A.,Fogg, Deryn E.
, p. 2387 - 2394 (2014)
A long-standing question in olefin metathesis centers on whether the release-return (boomerang) mechanism contributes to the productivity of Hoveyda-class catalysts. According to this mechanism, a molecule of o-isopropoxystyrene (A) is liberated during catalyst initiation, but recaptures the active catalyst following metathesis. The relevance of this pathway for the second-generation Hoveyda catalyst HII was assessed in metathesis of 1,1-and 1,2-disubstituted olefins. Crossover studies with 13C-labeled A*, as well as competition experiments involving ring-closing or cross metathesis (RCM, CM) in the presence of A (equimolar with HII) indicated rapid reuptake of styrenyl ether. The crossover studies indicated highly efficient catalyst initiation, with the entire catalyst charge being activated before metathesis was complete. In a comparative study involving CM of anethole with methyl acrylate, sustained activity was shown for HII, whereas the second-generation Grubbs catalyst GII was rapidly deactivated. These data demonstrate that the release-return mechanism is indeed operative for HII in these demanding metathesis reactions, and that facile shuttling from a protected recapture cycle into the productive metathesis cycle contributes to the superior performance of HII relative to GII.
E-senegasaponins a and b, Z-senegasaponins a and b, Z-senegins II and III, new type inhibitors of ethanol absorption in rats from Senegae Radix, the roots of Polygala senega L. Var latifolia Torrey et Gray
Yoshikawa,Murakami,Ueno,Kadoya,Matsuda,Yamahara,Murakami
, p. 350 - 352 (1995)
New inhibitors of ethanol absorption, E-senegasaponins a and b, Z-senegasaponins a and b, Z-senegins II and III, were isolated from Senegae Radix, the roots of Polygala senega L. var latifolia TORREY et GRAY, together with senegins II and III. Their chemical structures have been elucidated on the basis of chemical and physicochemical evidence, and the geometrical isomeric structures of methoxycinnamoyl moiety in each saponin were found to show tautomer-like behavior. The inhibitory effects of senegasaponins, senegins, and their related compounds have been examined, and some structure-activity relationships have been found.
Benzimidazol-2-ylidene ligated palladacyclic complexes of N,N-dimethylbenzylamine - Synthesis and application to C-C coupling reactions
Green, Kerry-Ann,Maragh, Paul T.,Abdur-Rashid, Kamaluddin,Lough, Alan J.,Dasgupta, Tara P.
, p. 38 - 43 (2016)
Palladacyclic complexes derived from N,N-dimethylbenzylamine (dmba) and the benzimidazol-2-ylidene ligands: 1,3-di(cyclohexyl)benzimidazol-2-ylidene (BzImCy), 1,3-di(tert-butyl)benzimidazol-2-ylidene (BzImtBu) and 1,3-di(1-adamantyl)benzimidazol-2-ylidene (BzImAd) were prepared. The yield for (BzImCy)Pd(Cl)dmba (2a) was 72% but yields for the more sterically encumbering analogues: (BzImAd)Pd(Cl)dmba (2b) and (BzImtBu)Pd(Cl)dmba (2c) were 34% and 38%, respectively. The complexes were obtained as off-white, moisture- and air-stable crystalline solids and were characterized by 1H NMR and 13C NMR spectroscopy, CHN analysis and IR spectroscopy. Complex 2c was further characterized by X-ray diffraction studies. The catalytic activity of all three complexes was explored for the Suzuki-Miyaura and Heck-Mizoroki coupling reactions of simple aryl bromides.
Synthesis of novel 1-phenyl-benzopyrrolizidin-3-one derivatives and evaluation of their cytoneuroprotective effects against NMDA-induced injury in PC12 cells
Cao, Jiafu,Li, Qiji,Liao, Xiu,Wang, Enhua,Wang, Li,Yang, Juan,Yang, Lishou,Yang, Qian,Yang, Xiaosheng,Yang, Yan
supporting information, (2022/02/23)
A range of novel 1-phenyl-benzopyrrolizidin-3-one derivatives were synthesized and evaluated for neuroprotective effects against N-methyl-?-aspartate (NMDA)-induced injury in PC12 cells. Interestingly, derivatives that 1-phenyl moiety bearing electron-donating group, especially benzyloxy, and the trans-forms exhibited better protective activity against NMDA-induced neurotoxicity. Compound 11 m demonstrated the best neuroprotective potency and shown a dose-dependent prevention. The increased intracellular calcium (Ca2+) influx caused by NMDA in PC12 cells was reversed in the case of compound 11 m pretreatment at 15 μM. These results suggested that the synthesized 1-phenyl-benzopyrrolizidin-3-one derivatives exerted neuroprotective effect on NMDA-induced excitotoxicity in PC12 cells associated with inhibition of Ca2+ overload and can be further optimized for the development of neuroprotective agents.
Aryl Diazonium Salts: Powerful Arylating Agents for Catellani-Typeortho-Arylation
Fu, Ying,Guo, Liang-Liang,Zhang, Yu-Xia
, p. 17437 - 17444 (2021/12/02)
The Catellani reaction provides an efficient synthetic approach to polyfunctionalized arenes. However, the selectiveortho-arylating reagents employed in these reactions have been strictly limited to activated bromoarenes. As demonstrated in this work, aryl diazonium salts bearing both electron-donating and electron-withdrawing substituents, after in situ transformations with KI into the corresponding iodoarenes, were efficient arylating reagents for Catellani typeortho-arylation approaches.
