1,721,302 research outputs found
Bis-calix[4]arenes with imine linkages: synthesis and binding study of thiopheno bis-calix[4]arene with viologens
No full textWe have developed an efficient synthetic pathway for various bis-calix[4]arenes with imine linkages by using a simple condensation procedure and carried out the binding study of thiopheno bis-calix[4]arene with biologically interesting viologen guests. (C) 2000 Elsevier Science Ltd. All rights reserved.X1128sciescopu
pi-conjugated dendrimers based on bis(enediynyl) benzene units
No full textWe have synthesized a new family of pi-conjugated dendrimers that are based on bis(enediynyl)benzene units by using both divergent and convergent approaches. The compounds at all three generations have strong bluish-green fluorescence, especially the third-generation dendrimer, which has the highest extinction coefficient and quantum efficiency in this series.X11233sciescopu
Synthesis and binding studies of multiple calix[4]arenes
No full textAs novel host molecules, various double and quadruple calix[4]arenes have been, synthesized by using quadruple cycloadditive macrocyclization, Schiff-base formation, and acylation. The interesting features of 'head-to-head' type multiple calix[4]arenes, such as the conformational aspects and cooperative binding, have been studied. (C) 2002 Elsevier Science Ltd. All rights reserved.X1132sciescopu
A NOVEL METHOD FOR THE CONVERSION OF THE ALCOHOL TO THE ALDEHYDE VIA 1,5-SILICON REARRANGEMENT
No full textA conceptually novel method for the conversion of alcohols to aldehydes is reported. The 1,5 - silicon rearrangement is involved as the key element of the reaction.X111sciescopu
ENANTIOSELECTIVE SYNTHESES OF (+)-METHYL NONACTATE AND (-)-METHYL 8-EPI-NONACTATE VIA ASYMMETRIC CYCLOADDITIVE ROUTE
No full textEnantioselective routes to (+)-methyl nonactate (2) and (-)-methyl 8-epi-nonactate (3) are described. The cornerstone of this synthetic strategy is a combination of asymmetric silyl nitronate cycloaddition and asymmetric reduction, which provides the key syn-1.3-diol intermediate 4.X1129sciescopu
Synthesis and enzyme inhibitory activities of novel peptide isosteres
No full textDesign and synthesis of metabolically stable peptide analogs that can either mimic or block the bioactivity of natural peptides or enzymes is an important constituent of bioorganic and medicinal chemistry research. Isosteric replacement of a scissile peptide bond represents a viable and popular approach in the rational design of peptidomimetics. Peptidomimetics find applications as drugs, in protein engineering and so on. This is evident from the wealth of therapeutically useful peptidomimetic leads incorporating any of the peptide isosteres that are currently available. In this review, we have given a brief account of the types of peptide isosteres widely known till date. With this background, we have described some of the recent developments in synthetic approaches. This includes methods involving a common intermediate to synthesize different possible isosteres and their peptide analogs, solid phase synthesis and combinatorial approach. One such method involving stereoselective nitrile oxide cycloaddition as the key step has been studied extensively in our research laboratory. Finally, we have also discussed about some of the recent reports on the design and inhibitory activities of peptidic or non-peptidic analogs against aspartic proteases (HIV-1, renin, ACE and pepsin) and peptide analogs of an immunomodulating hexapeptide.X1144sciescopu
Design and synthesis of calix[4]arene-nucleoside hybrids
No full textSynthesis of calixnucleosides (hybrid molecules between calix[4]arenes and nucleosides) has been achieved by amide bond formation between amine functional groups of para-1,3-diaminocalix[4]arene and carboxylic acid groups of thymidine nucleosides. Three types of calixnucleosides were efficiently prepared and X-ray crystallography of a homocoupled calixnucleoside revealed an interesting hydrogen-bonding pattern between thymine bases and the amide linkages. (C) 2002 Elsevier Science Ltd. All rights reserved.X1123sciescopu
A Fluorescent Probe for 3-Overhang of Telomeric DNA Based on Competition Between Two Interstrand G-Quadruplexes
No full textA 6-mer oligonucleotide containing a fluorescent U-Bod moiety has been used as a novel fluorescent probe for the 3'-overhang of telomeric DNA based on competition between non-fluorescent tetramolecular and fluorescent (3+1) intermolecular G-quadruplexes.open111815sciescopu
Syntheses and structural studies of calix[4]arene-nucleoside and calix[4]arene-oligonucleotide hybrids
No full textWe have synthesized three types of calix[4]arene- nucleoside hybrid efficiently by amide bond formation between the amine functional groups of 1,3-diaminocalix[4]arene and the carboxyl groups of thymidine nucleoside derivatives. X-ray crystallography of a homocoupled calix[4]arene-nucleoside hybrid revealed an interesting hydrogen bonding pattern between thymine bases and the amide linkages. We designed the calix[4]arene-oligonucleotide hybrids (5'-AAAAGATATCAAXTTGATATCTTTT-3', 5'-T-12-X-T-12-3', and 5'-A(12)-X-T-12-3') to be V-shaped oligodeoxyribonucleotides and synthesized them by using a calix[4]arene-nucleoside hybrid (X) as a key building block. Thermal denaturation experiments, monitored by UV spectroscopy at 260 and 284 nm, and circular dichroism spectra of the calix[4]arene-oligonucleotide hybrids suggest that the modified oligonucleotides indeed adopt V-shaped conformations, making them suitable for use as building blocks in the construction of programmed oligonucleotide nanostructures.open113534sciescopu
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