نتایج جستجو برای: Diels–Alder reaction
تعداد نتایج: 412405 فیلتر نتایج به سال:
During the last two decades, organic reactions in aqueous media have been attracting increasing attention. Furthermore, It has been established that some DielsAlder reaction dramatically accelerated in aqueous media. These have been alternatively ascribed to hydrophobic association of the reacting partners, micellar catalysis, solvophobicity, high internal solvent pressure, cohesive energy dens...
New L-serine derivative ligands were prepared and tested as co-catalyst in the DielsAlder reactions between cyclopentadiene (CPD) and methyl acrylate in the presence of several Lewis acids. The catalytic potential of the in situ formed complexes was evaluated based on the reaction yield. Bidentate serine ligands showed good ability to coordinate medium strength Lewis acids, thus boosting their ...
Substituted 1,4-phenanthrenequinones such as 1 are useful building blocks for the preparation of novel materials. Katz and others have shown that compounds such as 1 can be transformed into helicenes by DielsAlder reactions.1 Certain 1,4-phenanthrenequinones also have potential as synthetic intermediates for natural products synthesis. Additionally, some naturally occurring 1,4-phenanthrenequin...
The developing history of polymer materials tells that the invention of novel polymers with excellent performance is generally originated from the synthesis of new polymerizable monomers. Among kinds of monomers, benzocyclobutene (BCB) has attracted much interest because of its unique molecular structure and polymer properties (1-2). The structure of BCB is shown as following with the numbering...
One potential Lewis acid that has received negligible attention as a catalyst is the carbocation. Here we show the potential of triaryl methylium ions as highly powerful Lewis acid catalysts for organic reactions. The Lewis acidity of the triaryl methylium ion can be easily tuned by variation of the electronic properties of the aromatic rings and the catalytic activity of the carbocation is sho...
abstract in aggregate, active forms of reactive silica with mineral names are sometimes associated with sand and gravel in concrete mixture. alkali hydroxides originated from alkalis in the cement or other resources form an alkaline silica gel with this reactive silica which becomes swallowed and expanded during time causing damage to concrete. there have been growing researches on alkaline r...
in this thesis, a better reaction conditions for the synthesis of spirobarbiturates catalyzed by task-specific ionic liquid (2-hydroxy-n-(2-hydroxyethyl)-n,n-dimethylethanaminium formate), calcium hypochlorite ca(ocl)2 or n-bromosuccinimide (nbs) in the presence of water at room temperature by ultrasonic technique is provided. the design and synthesis of spirocycles is a challenging task becaus...
Kinetics of parallel reactions contribute to the elucidation of poly-step mechanisms. Competing pathways in the reaction of benzenediazonium ion with azide anion helped to establish the occurrence of phenylpentazole. Steady state kinetics clarified the competition between the interception of an intermediate and its return to the starting material. The DielsAlder reactions of cyclooctatetraene a...
we describe here a suitable approach for the synthesis of n-unsubstituted monocyclic b-lactams under mild reaction conditions by the annelation of imines with substituted acetylchlorides. in this method the reaily available phtalimidoacetyl chloride were allowed to react with - dibenzylideneiminotoluene (hydrobenzamide) in the presence of an equimolar amount of triethylamine in refluxing toluen...
1- in a search directed to the reaction of compound)23(the cycloaddition reaction of 1,3- diphenylisobenzofurane)14(with p-benzoquinone)19(,followed by addition of cyclopentadiene was carried out.the specific spacial stracture of its ir,nmr,mass spectra. 2- in another attempt the kinetic stability and behavior of compounds)20(and)23(was studied.the main subject of this study was the highly reve...
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