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101.
Dr. Koushik Chandra Dr. Tapta Kanchan Roy Dr. Deborah E. Shalev Prof. Abraham Loyter Prof. Chaim Gilon Prof. R. Benny Gerber Prof. Assaf Friedler 《Angewandte Chemie (International ed. in English)》2014,53(36):9450-9455
We present a new approach for peptide cyclization during solid phase synthesis under highly acidic conditions. Our approach involves simultaneous in situ deprotection, cyclization and trifluoroacetic acid (TFA) cleavage of the peptide, which is achieved by forming an amide bond between a lysine side chain and a succinic acid linker at the peptide N‐terminus. The reaction proceeds via a highly active succinimide intermediate, which was isolated and characterized. The structure of a model cyclic peptide was solved by NMR spectroscopy. Theoretical calculations support the proposed mechanism of cyclization. Our new methodology is applicable for the formation of macrocycles in solid‐phase synthesis of peptides and organic molecules. 相似文献
102.
Florent Jasinski Emeline Lobry Abraham Chemtob Céline Croutxe-Barghorn Loïc Vidal Ludovic Josien Jocelyne Brendlé Adrien Criqui 《Colloid and polymer science》2014,292(12):3095-3102
When finally processed to provide the function for which the latex was selected―binding, protecting, finishing―components such as surfactant, costabilizer or initiator become generally useless, not to say detrimental. In this study, we show that miniemulsion photopolymerization provides a suitable method to create latex without the apparent addition of these three compounds. Indeed, UV-driven monomer self-initiation can create initiating radicals without the aid of initiator, the fast in situ photogenerated polymer can hinder Ostwald ripening with the assistance of external costabilizer, and finally, UV-transparent clay can replace conventional surfactant to ensure colloidal stabilization. Each strategy has been developed individually before being combined together to end up with a unique miniemulsion procedure free of initiator, costabilizer and surfactant. Such approach paves the way to a simplified and environmentally improved pathway towards aqueous polymer dispersions. 相似文献
103.
Qualitative and semiquantitative study of the Liesegang rings formed by the reaction of oxalic acid and cadmium chloride in the acidic range of pH in silica hydrogel is made. The behaviour of Jablczynski's space constant and Morce-Pierce's time constant at various temperatures, pH and concentration of outer electrolyte is studied. The possible mechanisms for the above observed behaviour are suggested. The deviations from Isemura's general obserations are interprerted by considering two particular aspects, viz., comparatively larger crystals constituting the rings and the irreversibility of inner and outer electrolytes. 相似文献
104.
105.
Back Cover: Yoctoliter Thermometry for Single‐Molecule Investigations: A Generic Bead‐on‐a‐Tip Temperature‐Control Module (Angew. Chem. Int. Ed. 13/2014)
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106.
The use of bulky ligands in the rhodium-catalyzed reaction of aldehydes 7 (R1 = Ph) and 18 with 1-octyne increased the selectivity for ketones 13 and 20, to the detriment of ketones 12 and 19. Bulky phosphines reduced the hydroacylation reaction rate, leading to competition from the addition of the benzoic acid co-catalyst to the alkynes. This competing reaction can be suppressed by using the clay Montmorillonite K 10 (MK-10) as the co-catalyst instead of benzoic acid. 相似文献
107.
Defant [5] introduced the local Radon–Nikodym property for duals of locally convex spaces. This is a generalization of Asplund
spaces as defined in Banach space theory. In this paper we generalise Dunford"s Theorem [7] to Banach spaces with Schauder
decompositions and apply this result to spaces of holomorphic functions on balanced domains in a Banach space.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
108.
Reaction of N,N'-bis(phosphonomethyl)-1,10-diaza-18-crown-6 (H(4)L) with copper(II) acetate in 1:1 ethanol/water mixed solvents afforded a new crystal-engineered supramolecular metal phosphonate, Cu(H(2)L) (complex 1). By reaction of the same ligand with cadmium(II) nitrate in a 2:1 (M/L) ratio in methanol, a cadmium(II) complex with a 3D network structure was isolated, Cd(2.75)(L)(H(2)O)(7) x 1.5NO(3) x 7H(2)O x MeOH (complex 2). The copper(II) complex crystallized in the monoclinic space group P2(1)/c, with a =10.125(4), b = 14.103(6), and c = 14.537(6) A, beta = 91.049(8) degrees, V = 2075.4(16) A(3), and Z = 2. The Cu(II) ions in complex 1 are 6-coordinated by two phosphonate oxygen atoms, two nitrogen, and two oxygen atoms from the crown ether ring. Their coordination geometry can be described as Jahn-Teller-distorted octahedral, with elongated Cu-O(crown) distances (2.634(4) and 2.671(4) A for Cu(1) and Cu(2), respectively). The other two crown oxygen atoms remain uncoordinated. Neighboring two Cu(H(2)L) units are further interlinked via a pair of strong hydrogen bonds between uncoordinated phosphonate oxygen atoms, resulting in a one-dimensional supramolecular array along the a axis. The cadmium(II) complex is tetragonal, P4(2)/n (No. 86) with a = 20.8150(9) and c = 18.5846(12) A, V = 8052.0(7) A(3), and Z = 8. Among four cadmium(II) atoms in an asymmetric unit, one is 8-coordinated by four chelating phosphonate groups, the second one is 8-coordinated by 6 coordination atoms from a crown ring and two oxygen atoms from two phosphonate groups, the third Cd(II) atom is octahedrally coordinated by three aqua ligands and three phosphonate oxygen atoms from three phosphonate groups, and the fourth one is 6-coordinated by four aqua ligands and two oxygen atoms from two phosphonate groups in a distorted octahedral geometry. These cadmium atoms are interconnected by bridging phosphonate tetrahedra in such a way as to form large channels along the c direction, in which the lattice water molecules, methanol solvent, and nitrate anions reside. The effect of extent of deprotonation of phosphonic acids on the type of complex formed is also discussed. 相似文献
109.
Langlet A Latypov NV Wellmar U Bemm U Goede P Bergman J Romero I 《The Journal of organic chemistry》2002,67(22):7833-7838
Nitration of some 2-substituted pyrimidine-4,6-diones in sulfuric acid was studied, which afforded previously unknown 5,5-gem-dinitropyrimidine-4,6-diones in high yields. The gem-dinitro products were easily attacked by nucleophiles with concomitant formation of gem-dinitroacetyl derivatives, which in turn could be further hydrolyzed to salts of dinitromethane and triureas. 相似文献
110.
A microscopic, driven lattice gas model is proposed for the dynamics and spatiotemporal fluctuations of the precursor film observed in spreading experiments. Matter is transported both by holes and particles, and the distribution of each can be described by driven diffusion with a moving boundary. This picture leads to a stochastic partial differential equation for the shape of the boundary. Explicit analytic results are obtained which agree with the simulations of the lattice gas. 相似文献