54752-10-2Relevant articles and documents
A novel bifunctional chelating agent based on bis(hydroxamamide) for 99mTc labeling of polypeptides
Ono, Masahiro,Ohgami, Masatsugu,Haratake, Mamoru,Saji, Hideo,Nakayama, Morio
experimental part, p. 71 - 79 (2012/06/30)
This paper describes the synthesis and biological evaluation of a novel bifunctional chelating agent (BCA) based on bis(hydroxamamide) for 99mTc labeling of polypeptides. We successfully designed and synthesized C3(BHam)2·COOH as a new BCA. C 3(BHam)2·COOH formed a stable 99mTc complex and enabled us to prepare 99mTc-labeled polypeptides by using a 2,3,5,6-tetrafluorophenol (TFP) active ester of C3(BHam) 2·COOH. 99mTc-C3(BHam) 2·HSA prepared with C3(BHam)2·TFP was stable in both murine plasma and an excess of l-cysteine without any dissociation of 99mTc from polypeptides. Furthermore, the blood clearance of 99mTc-C3(BHam)2·HSA in mice was similar to that of 125I-HSA, suggesting that C 3(BHam)2·COOH retained stable binding between 99mTc and the polypeptides in vivo. When 99mTc-C 3(BHam)2·NGA was injected into mice, the radioactivity showed high hepatic uptake early on and a rapid clearance from the liver, indicating that C3(BHam)2·COOH did not affect the pharmacokinetics of polypeptides in vivo and gave radiometabolites, which displayed a rapid elimination from the liver. Such characteristics would render C3(BHam)2·COOH attractive as a new BCA for 99mTc labeling of polypeptides. Copyright
Kinetics of methanolysis of substituted benzamide O-(phenoxycarbonyl)- and O-(alkoxycarbonyl)oximes catalyzed by sodium methanolate
Dusek, Libor,Kavalek, Jaromir,Sterba, Vojeslav
, p. 265 - 287 (2007/10/03)
The kinetics of methanolysis of substituted benzamide O-(phenoxycarbonyl)-and O-(alkoxycarbonyl)oximes catalyzed by sodium methanolate was studied at 25 °C. The reaction proceeds in two steps. In the first, faster step, the substituted phenoxy group is exchanged for a methoxy group giving rise to substituted O-(methoxycarbonyl)oximes. In the second step, a benzamide oxime is eliminated and dimethyl carbonate is formed. The slope of the plot of the rate constant in dependence on the sodium methanolate concentration has an increasing tendency in both steps. In the presence of 18-crown-6, the plots are linear and the rate constants are lower than in the absence of the crown ether. The rate constants of the reaction of the substrate with the methanolate ion and with the MeONa ion pair were determined assuming that the sodium cation-catalyzed reactions constitute the rate-determining step of the reaction of the substrate with the MeONa ion pair. For the elimination of the aryloxy group and of the substituted benzamide oxime, the rate constants of the reaction with the ion pair are roughly twelvefold and twentyfold higher, respectively, than in the uncatalyzed reaction. The slope of the dependence of log k on the pKa of the substituted phenols (β1g) has the value of -0.52 for the uncatalyzed reaction of elimination of the substituted phenoxy group, -0.83 for the elimination of the benzamide oxime group, and -0.53 for the reaction with the ion pair. In the first step and probably also in the second step, the reaction proceeds by the concerted mechanism. The relatively high ρ value of methanolysis of substituted benzamide O-(4-nitrophenoxycarbonyl)oximes, 0.63, suggests that the structure of the transition state approaches that of the tetrahedral intermediate.
Heterocycles from Nitrile Oxides. 3. 1,2,4-Oxadiazol-5(4H)-ones
Hussein, Ahmad Q.
, p. 127 - 128 (2007/10/02)
The reaction of nitrile oxides with potassium cyanate gives 3-aryl-1,2,4-oxadiazol-5(4H)-ones (5).These heterocycles are also obtained by cyclization of the corresponding O-carbethoxyamidoximes (7) with sodium ethoxide.
