نتایج جستجو برای: ring substitution
تعداد نتایج: 177743 فیلتر نتایج به سال:
Cyclopentadienide (Cp) groups are among the most popular ligands in organometallic chemistry. Sterically demanding substitution patterns on Cp ring can have an important effect ligand properties and there many examples of metal complex which only stable isolatable with sterically ligands, carrying alkyl or aryl groups. Among these pentaisopropylcyclopentadienide is bulkiest pentaalkyl derivativ...
Mechanical methods for single-molecule control have potential for wide application in nanodevices and machines. Here we demonstrate the operation of a single-molecule switch made functional by the motion of a phenyl ring, analogous to the lever in a conventional toggle switch. The switch can be actuated by dual triggers, either by a voltage pulse or by displacement of the electrode, and electro...
We compare the duplex stabilizing properties of 2'-fluorinated nucleic acid analogues with furanose and non-furanose ring systems and dissect the relative contributions of hydration, sugar conformation, and fluorine configuration toward the overall T(m) value. We find that the stabilization imparted by fluorine substitution is additive over that obtained by restricting the conformation of the s...
Electrophilic aromatic substitution reactions of pyridines are extraordinarily challenging. Instead of C-substitution at the pyridine ring, the electrophile typically forms an adduct with the pyridine nitrogen, which even further deactivates the already electron deficient pyridine ring toward electrophilic substitution. For example, the direct nitration of pyridine may require a reaction temper...
A number of N-arylmethyl substituted indole derivatives have been synthesized and their effectiveness against ADP and arachidonic acid induced platelet aggregation in human plasma was determined. The desired compounds were synthesized by reacting the appropriate aniline derivative with isatin (or substituted isatin) to form the corresponding imine structures. The so formed compound was then act...
Four known flavonoids: quercetin 3-O-β-D-rutinoside (Q3Rut), myricetin 3-O-β-D-galactopyranoside (M3Gal), quercetin 3-O-β-D-galactopyranoside (Q3Gal) and quercetin 3-O-β-D-glucopyranoside (Q3Glc), for the first time were isolated from aerial parts of Euphorbia microsciadia. The chemical structure of them was elucidated on the basis of 1 and 2 D-NMR spectra and different spectroscopic techniques...
A number of N-arylmethyl substituted indole derivatives have been synthesized and their effectiveness against ADP and arachidonic acid induced platelet aggregation in human plasma was determined. The desired compounds were synthesized by reacting the appropriate aniline derivative with isatin (or substituted isatin) to form the corresponding imine structures. The so formed compound was then act...
Various monoand disubstituted cinnamic acid derivatives and aromatic carboxylic acids with saturated side chains were incubated mainly with Bacillus, Candida, Hansenula, and Saccharo m yces strains. The cinnamic acids carrying a hydroxyand/or a methoxy group at the 3and/or 4-position of the benzene ring were decarboxylated with high yields. Most of the reactions were terminated within 24 to 48...
The reaction between Ph2PH and C6F5CNS leads to the formation of the polyfluorinated benzothiazolephosphine ligand Ph2P(CNS)(C6F4) 1. The mechanism of the reaction involves the addition of the phosphine to the isothiocyanate and subsequent intramolecular nucleophilic aromatic substitution. This new ligand reacts with gold(I) substrates producing complexes [AuCl{Ph2P(CNS)(C6F4)}] 2 and [Au(C6F5)...
(2)] The first examples of uncharged aryl substituted fluorinated hydridophosphazenes, N3P3F4(Ar)H [Ar — C6H5 (1), pwere obtained in an unprecedented manner upon fluorination of diaryloctachlorobi(cyclophosphazenes) ðN6P6Cl8ðArÞ2Þ [Ar — C6H5, p-ClC6H4] using KF in acetonitrile. The compounds (1) and (2) were stable to air and moisture, and were characterized by spectral and analytical methods. ...
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