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Metal Fragment (metal + fragment)
Selected Abstracts[2+2+2]-Cycloaddition of 4-Hydroxy-Substituted Enediynes to 2-Hydroxy-Substituted DecahydrophenanthrenesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2003Ulrich Groth Abstract Enediynes rac - 4 were prepared in seven steps with an overall yield of 31% starting from 4-pentyn-1-ol (5). A cobalt mediated [2+2+2]-cycloaddition of these enediynes and subsequent removal of the metal fragment afforded the decahydrophenanthrenes rac - 3/13 in 37,56% yield. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] A Straightforward Synthesis of N -Functionalized ,-DiiminesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 2 2003Alexandrine Maraval Abstract Reaction of Schwartz's reagent [Cp2ZrHCl]n (1) (one or two equivalents) with gem -dinitrile compounds of the type X(CN)2 [X = CMe2, CBenz2, P(NiPr2)2] gives the corresponding mono- and di- N -zirconated imino complexes selectively. Substitution reactions of the zirconocene metal fragment with electrophiles such as, for example, chlorophosphanes of the type R2PCl, acid chlorides RC(O)Cl or the iminium salt [CH2NMe2]Cl allowed the preparation of a large variety of stable N -functionalized mono- and ,-diimine derivatives. The nature of the X group is of particular importance for the success of the substitution reaction step. The X-ray crystal structures obtained for the N -functionalized gem -aldimino-nitrile compounds 9, 10b, the N -phosphorylated ,-diimine 32, and the gem -formyl nitrile derivative 12b are presented. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] The [Tc(N)(PNP)]2+ metal fragment labeled cholecystokinin-8 (CCK8) peptide for CCK-2 receptors imaging: in vitro and in vivo studiesJOURNAL OF PEPTIDE SCIENCE, Issue 4 2007Stefania Agostini Abstract The radiolabeling of the natural octapeptide CCK8, derivatized with a cysteine residue (Cys-Gly-CCK8), by using the metal fragment [99mTc(N)(PNP3)]2+ (PNP3 = N,N -bis(dimethoxypropylphosphinoethyl)methoxyethylamine) is reported. The [99mTc(N)(NS-Cys-Gly-CCK8)(PNP3)]+ complex was obtained according to two methods (one-step or two-step procedure) that gave the desired compound in high yield. The complex is stable in aqueous solution and in phosphate buffer. In vitro challenge experiments with an excess of cysteine and glutathione indicate that no transchelation reactions occur, confirming the high thermodynamic stability and kinetic inertness of this compound. Stability studies carried out in human and mouse serum, as well as in mouse liver homogenates, show that the radiolabeled compound remains intact for prolonged incubation at 37 °C. Binding properties give Kd (19.0 ± 4.6 nmol/l) and Bmax (,106 sites/cell) values in A431 cells overexpressing the CCK2-R. In vivo evaluation of the compound shows rapid and specific targeting to CCK2-R, a fourfold higher accumulation compared to nonreceptor expressing tumors. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd. [source] Utilization of Self-Sorting Processes To Generate Dynamic Combinatorial Libraries with New Network TopologiesCHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2006Isabelle Saur Dr. Abstract The synthesis of water-soluble, organometallic macrocycles is described. They were obtained by self-assembly in reactions of the half-sandwich complexes [{Ru(C6H5Me)Cl2}2], [{Ru(p -cymene)Cl2}2], [{Rh(Cp)Cl2}2], and [{Ir(Cp*)Cl2}2] with the ligand 5-dimethylaminomethyl-3-hydroxy-2-methyl-4-(1H)-pyridone in buffered aqueous solution at pH 8. The structure of the Ru,(p -cymene) complex was determined by single-crystal X-ray crystallography. Upon mixing, these complexes undergo scrambling reactions to give dynamic combinatorial libraries. In combination with structurally related complexes based on amino-methylated 3-hydroxy-2-(1H)-pyridone ligands, an exchange of metal fragments but no mixing of ligands was observed. This self-sorting behavior was used to construct dynamic combinatorial libraries of macrocycles, in which two four-component sub-libraries are connected by two common building blocks. This type of network topology influences the adaptive behavior of the library as demonstrated in selection experiments with lithium ions as the target. [source] | ||||||||||