نتایج جستجو برای: heck cross
تعداد نتایج: 491365 فیلتر نتایج به سال:
Nannocystin A is a 21-membered cyclodepsipeptide showing remarkable anticancer properties. Described is the total synthesis of nannocystin A, which features an asymmetric vinylogous Mukaiyama aldol reaction for efficient assembly of the penultimate open-chain precursor and a pivotal intramolecular Heck cross-coupling for the final macrocyclization.
A conjugated alternating copolymer containing norbornadiene and bis(ethynylene)phenylene units was prepared by the Cassar-Heck-Sonogashira cross-coupling reaction. Its electroluminescence was tested in a device, and its fluorescence colour could be tuned by light-induced norbornadiene-quadricyclane isomerization.
Palladium nano-crystals increase in size during the initial recycling in Heck cross coupling reactions. We demonstrate that oxygen adsorbed on the surface of palladium nano-crystals plays a pivotal role in driving the ripening. This in turn is associated with a loss in catalytic activity.
Cinnamic acid derivatives bearing a nitroxyl moiety (2,2,6,6-tetramethyl-1-oxyl-4-piperidyl 3-E-aryl acrylates) were synthesized in 30-100% yield using a Mizoroki-Heck cross-coupling reaction between 4-acryloyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl and iodobenzene derivatives in the presence of palladium(II) acetate coordinated with a tri(o-tolyl)phosphine ligand immobilized in a polyurea mat...
the application of the [pd{c6h3(ch2ch2nh2)-4-ome-5-κ2-c,n}(μ-br)]2 complex of 2-methoxyphenethylamine in the heck coupling reaction was considered under both conventional and microwave irradiation conditions, and their results were compared. this complex is an efficient, stable and non-sensitive to air and moisture catalyst for the vinylation of substituted aryl halides with different electroni...
Pd(II)-chitosan composite nanofibres of 62 ± 9 nm diameter are efficient catalysts for Heck cross-coupling reactions. Using a model reaction of iodo-benzene and n-butyl acrylate, we demonstrate that this material can be used as a recyclable catalytic support with a very low loading of palladium (0.17 mol% Pd).
A flexible and divergent synthesis of cryptophycin unit A analogues is described. This method relies on iridium-catalysed stereo- and enantioselective crotylation and chemoselective one-pot oxidative olefination to access common intermediate . Heck, cross metathesis, and Suzuki-Miyaura reactions are illustrated for the generation of methyl ester unit A analogues .
We report an effective synthetic protocol to access [6,6]-bicyclic lactone moieties through a regio- and stereoselective intramolecular Mizoroki-Heck cross-coupling reaction followed by a 6π-electrocyclization. This method enabled the first synthesis of the elusive CD fragment of the Erythrina alkaloid DHβE. Preliminary pharmacological evaluations support the notion that the key pharmacophores ...
a new dimeric orthopalladated complex was synthesized via reaction of 2,3-dimethoxy benzaldehyde oxime with palladium chloride and lithium chloride in methanol as solvent and sodium acetate as base at room temperature. the catalytic activity of this dimeric [pd{c6h2(-ch=noh)-(ome)2-2,3}(µ-cl)]2 complex as an efficient, air, and moisture tolerant catalyst was investigated in mizoroki–heck cross ...
Considerable efforts have been undertaken by numerous groups in academia and industry over the past decade to expand the repertoire of coupling reagents in palladium(0)-catalyzed cross-coupling reactions. In particular, alkenyl phosphates and tosylates have proven their worth in various cross-coupling reactions, such as the Stille, Suzuki, 3] Negishi, Kumada, Sonogashira, b,e,f,5] Buchwald–Hart...
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