نتایج جستجو برای: quaternary phosphonium
تعداد نتایج: 15248 فیلتر نتایج به سال:
Certain (Z)-1,5-syn-diols 2 may be converted into 2,6-trans-5,6-dihydropyrans by using phosphonium salt 4 or phosphorane 5 as dehydrating agents. A more general four step procedure converts the (Z)-1,5-syn-endiols into enantiomeric dihydropyrans ent-3 via regioselective silylation of the allylic alcohol unit followed by mesylate formation and base-promoted nucleophilic displacement.
We report a simple and rapid microwave-assisted method for the preparation of oligosaccharide-glycosylamines, followed by labelling with tris(2,4,6-trimethoxyphenyl)phosphonium acetic acid N-hydroxysuccinimide ester. The facile strategy introduced a permanent charge at the reducing end of the oligosaccharide. In combination of MALDI-MS, the detection limit for maltoheptaose was as low as 2 fmol...
the wittig reaction rate can be dramatically enhanced by irradiation of the reaction mixture containing an aldehyde or ketone; methoxymethyl(triphenyl)phosphonium chloride, potassium t-butoxide, and t buoh with a commercial microwave oven. carbonyl compound are converted to witting products within three min. in good yields.
A new non-fluorinated malonamide-based ionic liquid extractant was synthesized and investigated for the extraction behavior of europium(III) and other trivalent rare-earth ions from nitric acid medium. The extractant was the functionalized ionic liquid trihexyl(tetradecyl)phosphonium N,N,N',N'-tetra(2-ethylhexyl)malonate, [P66614][MA], and it was used in combination with the non-fluorinated ion...
UNLABELLED Mitochondrial membrane potential (DeltaPsim)-dependent enhanced uptake of phosphonium salts, including (3)H-tetraphenylphosphonium ((3)H-TPP), in tumor cells, suggests the potential use of phosphonium salts as tracers for tumor imaging. In this study, we characterize the tumor accumulation of (3)H-TPP and compare it with (18)F-FDG in cell culture and in xenograft, metastatic, and inf...
The first examples of arylphosphonium salts containing a dicarba-closo-dodecaborane(12) (closo-carborane) are reported; in contrast to the 1,12-carborane derivative, the 1,2- and 1,7-isomers undergo a facile deboronation reaction in polar solvents to afford the corresponding nido-carborane phosphonium zwitterions.
The phosphonium borane [p-Mes(2)B(C(6)H(4))PMePh(2)](+) complexes fluoride in water containing 10% methanol with a binding constant of 1.0(+/-0.1) x 10(3) M(-1) to afford the zwitterion p-Mes(2)FB(C(6)H(4))PMePh(2).
Herein we report the chemotactic behaviour of self-propelled droplets composed solely of the ionic liquid trihexyl(tetradecyl)phosphonium chloride ([P(6,6,6,14)][Cl]). These droplets spontaneously move along an aqueous-air boundary in the direction of chloride gradients to specific destinations due to asymmetric release of [P(6,6,6,14)](+) cationic surfactant from the droplet into the aqueous p...
P-Hydroxytetraorganophosphorane, the long-postulated intermediate in phosphonium salt and ylide hydrolysis, has been observed and characterised by low temperature NMR, finally definitively establishing its involvement in these reactions. The results require modification of the previously accepted mechanism for ylide hydrolysis: P-hydroxytetraorganophosphorane is generated directly by 4-centre r...
Di- and tetraphosphines with rigid phenyl-, biphenyl-, and tetraphenylstannane, -silane, and -methane scaffolds, and various substituents R, have been synthesized and immobilized via triethoxysilane-propagated formation of one or two surface-bound phosphonium moieties. The remaining phosphine groups can be coordinated to metal complexes. All the detective work and proof is done by solid-state N...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید