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Selective Functionalization (selective + functionalization)
Selected AbstractsTowards a Selective Functionalization of Amino-Terminated DendrimersEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2004Fritz Vögtle Abstract Selective functionalization of the periphery of commercial polypropyleneamine (POPAM) and polyamidoamine (PAMAM) dendrimers has been investigated in preparative scale. The first generation (G1) POPAM dendrimer was for the first time selectively N,N -bis(sulfonylated) with tosyl chloride and the corresponding mono-, di-, tri-, and tetra- N -tosylsulfonamides were isolated and fully characterized. Unexpectedly, similar persulfonylation of G2 POPAM results in splitting of a central C,N bond and only fully and partially sulfonylated halves of the initial dendrimer could be isolated. Higher generations of POPAM are also split during the persulfonylation yielding complex mixtures of persulfonylated dendritic fragments which could hardly be identified. A plausible mechanism of the POPAM decomposition on the basis of the reaction product analysis is proposed. N -Sulfonylation of a peripheral octasulfonamide of G2 POPAM with tosyl chloride also leads to the destruction of the dendrimer, while its N -alkylation with benzyl bromide proved to be not selective yielding a completely alkylated derivative. Unlike POPAM dendrimers, PAMAM dendrimers were shown to be more stable during their sulfonylation and no decomposition of the dendritic backbone was detected. In contrast to the POPAM dendrimers, PAMAM dendrimers were shown to be rather inert with respect to the formation of N -tosylsulfonamides since they could only be N -monosulfonylated at all peripheral amino groups. The combination of MALDI-TOF and ESI-FT-ICR tandem mass spectrometry has been shown to be an effective method for structure assignment and purity check of selectively or fully persulfonylated dendritic oligoamines. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Spatially Selective Functionalization of Conducting Polymers by "Electroclick" ChemistryADVANCED MATERIALS, Issue 44 2009Thomas Steen Hansen Conducting polymer microelectrodes can electrochemically generate the catalyst required for their own functionalization by "click chemistry" with high spatial resolution. Interdigitated microelectrodes prepared from an azide-containing conducting polymer are selectively functionalized in sequence by two alkyne-modified fluorophores by control of the applied potentials. [source] "Plastic Trash goes Biohybrid",Rapid and Selective Functionalization of Inert Plastic Surfaces with Biomolecules,MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 2 2010Stefan M. Schiller Abstract The covalent functionalization of "inert" polymers such as polypropylene with biomolecules for biocompatible or biosensor surfaces is challenging. Here we present a powerful approach to covalently modify "inert" macromolecular surfaces with biomacromolecules reusing old plastic material. A special emphasis was placed on easily accessible materials and a process which is easy, fast, efficient, cheap, and reliable. "Plastic trash" (lids from Eppendorf® pipet tip containers) was used as a polymer substrate to demonstrate the use/reuse of commercial packing material to covalently modify this material with a thin reactive plasma polymerized maleic anhydride nanolayer network, which can be subsequently modified with biomolecules for various applications, e.g., in tissue engineering and as biochips. [source] ChemInform Abstract: A Practical Non-Cryogenic Process for the Selective Functionalization of Bromoaryls.CHEMINFORM, Issue 46 2008Fabrice Gallou Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Selective Functionalization of Hydrocarbons by Nitric Acid and Aerobic Oxidation Catalyzed by N-Hydroxyphthalimide and Iodine under Mild Conditions.CHEMINFORM, Issue 49 2003Francesco Minisci Abstract For Abstract see ChemInform Abstract in Full Text. [source] Successive Iodine,Magnesium or ,Copper Exchange Reactions for the Selective Functionalization of Polyhalogenated Aromatics.CHEMINFORM, Issue 31 2003Xiaoyin Yang Abstract For Abstract see ChemInform Abstract in Full Text. [source] A Simple Method for the Preparation and Selective Functionalization of 4,5-Diaminopyrazoles.CHEMINFORM, Issue 27 2003Benjamin E. Blass Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: The Tellurium,Lithium Exchange Reaction: Selective Functionalization of Electron-Deficient Heteroaromatics.CHEMINFORM, Issue 31 2001Osamu Sugimoto Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Towards a Selective Functionalization of Amino-Terminated DendrimersEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 22 2004Fritz Vögtle Abstract Selective functionalization of the periphery of commercial polypropyleneamine (POPAM) and polyamidoamine (PAMAM) dendrimers has been investigated in preparative scale. The first generation (G1) POPAM dendrimer was for the first time selectively N,N -bis(sulfonylated) with tosyl chloride and the corresponding mono-, di-, tri-, and tetra- N -tosylsulfonamides were isolated and fully characterized. Unexpectedly, similar persulfonylation of G2 POPAM results in splitting of a central C,N bond and only fully and partially sulfonylated halves of the initial dendrimer could be isolated. Higher generations of POPAM are also split during the persulfonylation yielding complex mixtures of persulfonylated dendritic fragments which could hardly be identified. A plausible mechanism of the POPAM decomposition on the basis of the reaction product analysis is proposed. N -Sulfonylation of a peripheral octasulfonamide of G2 POPAM with tosyl chloride also leads to the destruction of the dendrimer, while its N -alkylation with benzyl bromide proved to be not selective yielding a completely alkylated derivative. Unlike POPAM dendrimers, PAMAM dendrimers were shown to be more stable during their sulfonylation and no decomposition of the dendritic backbone was detected. In contrast to the POPAM dendrimers, PAMAM dendrimers were shown to be rather inert with respect to the formation of N -tosylsulfonamides since they could only be N -monosulfonylated at all peripheral amino groups. The combination of MALDI-TOF and ESI-FT-ICR tandem mass spectrometry has been shown to be an effective method for structure assignment and purity check of selectively or fully persulfonylated dendritic oligoamines. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Aromatic and Benzylic C,H Bond Functionalization Upon Reaction between Nitriles and Perfluoroalkyl SulfoxidesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 31 2009Yohan Macé Abstract We studied the thermal behavior of some intermediates formed by reaction of nitriles with perfluoroalkyl sulfoxides upon trifluoromethanesulfonic anhydride activation. Bistriflate ketal 3, precursor of sulfilimine 1, may undergo a rearrangement to sulfanyl nitrile 5 after triflic acid elimination under thermal conditions. With p -tolyl trifluoromethyl sulfoxide, remote triflic acid elimination from intermediate 4 leads to benzamide 8 formation. These reactions involve, respectively, selective functionalization of the aromatic ortho C,H bond or the benzylic C,H bond para to the sulfoxide group. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Synthesis and In Vitro Evaluation of 2-Aminoquinazolin-4(3H)-one-Based Inhibitors for tRNA-Guanine Transglycosylase (TGT)HELVETICA CHIMICA ACTA, Issue 6 2004Emmanuel tRNA-Guanine transglycosylase (TGT) plays a key role in the post-transcriptional modification of tRNA. It has been linked with the pathogenicity of shigellae, the causative agents of bacillary dysentery (shigellosis). Here, we report structureactivity relationships (SARs) for a new series of 2-aminoquinazolin-4(3H)-one-based inhibitors of TGT, resulting from structure-based design (Fig.,2). Versatile synthetic protocols allow selective functionalization of the 2-aminoquinazolin-4(3H)-one core (Schemes,1,6) with H-bond-donor groups in position 6 (for H-bonding to the C=O group of Leu231) and lipophilic residues in position 8 for reaching into a shallow, newly discovered lipophilic pocket lined by Val282, Val45, and Leu68. The binding mode of several of these ligands in the active site of TGT was established by crystal structure analyses (Figs.,4 and 6). A dramatic S effect was observed, with the replacement of the S-atom in the (phenylsulfanyl)methyl residue in position 8 of inhibitor 1c (Ki=100,nM) by the O-atom (in 1h, Ki=5.6,,M) or CH2 (in 1i, Ki=3.6,,M), resulting in a massive loss of activity (Fig.,3). Crystal structure analysis showed that the lipophilic Me group points into a highly polar region of the active site encompassed by the side chains of Asp280 and Asp102 and collides directly (d(C,,,O)=3.1,Å) with one of the O-atoms of the carboxylate of Asp102. Similarly, lipophilic linkers departing from position 8 and orienting residues in the shallow hydrophobic pocket presumably encounter analogous unfavorable contacts, accounting for the modest contribution to the binding free enthalpy upon introduction of these residues. These findings provide a valuable starting point for future structure-based lead optimization cycles leading to TGT inhibitors with increased in vitro potency. [source] Stereoselective Functionalization of 2-(1-Aminoalkyl)aziridines via Lithiation of Aziridine,Borane ComplexesCHEMISTRY - A EUROPEAN JOURNAL, Issue 15 2005José M. Concellón Prof. Dr. Abstract Highly selective functionalization of the aziridine ring of (2S,1,S)-2-(1,-aminoalkyl)aziridines 1, through successive formation of aziridine,borane complexes, lithiation, treatment with a variety of electrophiles and final decomplexation is described. The influence of the structure of the starting complexes 2 and of the electrophiles in the stereoselectivity of this process has been studied. Finally, successive double lithiation,electrophile reactions were carried out affording enantiopure 1,2,3,3-tetrasubstituted aziridine,borane complexes with high selectivity. Se describe la funcionalización altamente selectiva de (2S,1,S)-2-(1,-aminoalquil)aziridinas 1 a través de un proceso de formación de complejos borano,aziridina, litiación, tratamiento con electrófilos y descomplejación. También ha sido objeto de estudio la influencia de la estructura de los complejos 2 y de los electrófilos en el proceso. Finalmente, se ha llevado a cabo una doble reacción litiación y reacción con electrófilos dando lugar a complejos borano,aziridina 1,2,3,3-tetrasustituidas de forma enantiopura y con alta selectividad. [source] | |||||||||||||||||||||||||