نتایج جستجو برای: 13 dipolar cycloaddition
تعداد نتایج: 343672 فیلتر نتایج به سال:
The cycloaddition of azomethine ylides to [60]fullerene (C60) has been studied in ortho-dichlorobenzene (o-DCB) by evaluating the impact an ionic liquid (IL) additive. solvent effect addressed activation parameters and boosting microwave (MW) induced dielectric heating. IL additive plays a twofold role stabilizing dipolar ylide intermediate favoring retro-cycloaddition at high temperature regim...
Simple haloaldehydes, including enolisable aldehydes, were found to be suitable for the formation of cyclic products by cascade (domino) condensation, cyclisation, dipolar cycloaddition chemistry. This multi-component reaction approach to heterocyclic compounds was explored by using hydroxylamine, a selection of aldehydes, and a selection of activated dipolarophiles. Initial condensation gives ...
Common cases of cycloaddition include concerted (2 + 4) and stepwise (2 + 2) reactions which latter are usually easily recognizable as involving biradicals or dipolar ions. The addition in situ of dichioroketene to 2,4-hexadiene and 2butene is stereospecific, as required by the (2 + 2a) mechanism, but is followed by rapid base-catalysed rearrangement of the resulting 2,2-dichiorocyclobutanones ...
1-Sulfonyl-1,2,3-triazoles, which are readily available through copper-catalyzed azide-alkyne cycloaddition, are stable precursors to Rh–azavinyl carbenes, as well as carbene complexes of other metals. Among other transformations, these reactive intermediates can be used for the introduction of a nitrogen atom into various heterocycles that are important in both synthetic and medicinal chemistr...
Chiral pyrrolidines and pyrrolizidines with spirooxindole ring systems are the central skeletons for numerous alkaloids and pharmacologically important compounds. Gelesmine, pseudotabersonine, formosanine, isoformosanine, morroniside and mitraphylline are some of the alkaloids containing spirooxindole ring systems. Derivatives of spirooxindole find very wide biological applications as anti micr...
An efficient one-pot three-component procedure for the synthesis of new chiral spiro oxindolopyrrolidines/pyrrolizidines with highly regio- and diastereo-enantio, selective from 1,3-dipolar cycloaddition of azomethine ylides and chiral menthol-drived trans-cinnamic are described. The mechanism of the reaction is discussed on basis of the assignment of the absolute configuration of one of the cy...
The 1,3-dipolar cycloaddition of 3-nitro-2(1H)-quinolones with ester-stabilized azomethine ylides derived from sarcosine ester and various aromatic aldehydes has been investigated. structure stereochemistry cycloadducts were studied in detail by X-ray NMR spectroscopy methods.
an efficient one-pot three-component procedure for the synthesis of new chiral spiro oxindolopyrrolidines/pyrrolizidines with highly regio- and diastereo-enantio, selective from 1,3-dipolar cycloaddition of azomethine ylides and chiral menthol-drived trans-cinnamic are described. the mechanism of the reaction is discussed on basis of the assignment of the absolute configuration of one of the cy...
1,3-Dipolar cycloaddition of pyridynes and organic azides was investigated. Thus, 3,4-pyridynes and 2,3-pyridynes were reacted with various organic azides under mild conditions to afford the corresponding [1,2,3]triazolo[4,5-c]pyridines and [1,2,3]triazolo[4,5-b]pyridines, respectively. In the case of the reaction of 3,4-pyridyne, it was also found that a substituent on pyridine ring affected t...
A synthetic approach to the modification of drug Riluzole with pharmacologically active fragments (adamantane, carbazole, tetrahydrocarbazole, γ-carboline, and phenothiazine) was proposed, which is based on copper-catalyzed alkyne-azide 1,3-dipolar cycloaddition azide-containing pharmacophores alkyne-containing derivatives Riluzole.
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