13734-34-4Relevant articles and documents
Synthesis of cyclic peptides through ring-closing metathesis of photolabile protecting groups
Hoffmann, Judith,Kazmaier, Uli
, p. 411 - 420 (2015)
The new photolabile protecting groups 4-allyl-5-methoxy-3-nitrobenzyl (AMNB) and 4-allyl-5-methoxy-3-nitrobenzyloxycarbonyl (AMNBOC) with an allylic side chain can easily be obtained from vanillin. These protecting groups can be introduced on the C- as well as on the N-terminus of peptides, and subsequent ring-closing metatheses provides a straightforward protocol for the synthesis of cyclic peptides. The protecting groups can be removed under UVA irradiation (365 nm).
Efficacious anticancer drug delivery mediated by a pH-sensitive self-assembly of a conserved tripeptide derived from tyrosine kinase NGF receptor
Moitra, Parikshit,Kumar, Krishan,Kondaiah, Paturu,Bhattacharya, Santanu
, p. 1113 - 1117 (2014)
We present herein a short tripeptide sequence (Lys-Phe-Gly or KFG) that is situated in the juxtamembrane region of the tyrosine kinase nerve growth factor (Trk NGF) receptors. KFG self-assembles in water and shows a reversible and concentration-dependent switching of nanostructures from nanospheres (vesicles) to nanotubes, as evidenced by dynamic light scattering, transmission electron microscopy, and atomic force microscopy. The morphology change was associated with a transition in the secondary structure. The tripeptide vesicles have inner aqueous compartments and are stable at pH 7.4 but rupture rapidly at pH≈6. The pH-sensitive response of the vesicles was exploited for the delivery of a chemotherapeutic anticancer drug, doxorubicin, which resulted in enhanced cytotoxicity for both drug-sensitive and drug-resistant cells. Efficient intracellular release of the drug was confirmed by fluorescence-activated cell sorting analysis, fluorescence microscopy, and confocal microscopy. Package for special delivery: A biologically active tripeptide self-assembles to produce nanovesicles at lower concentrations and nanotubes at higher concentrations (see scheme). The nanovesicles rupture at pH≈6 and are highly efficient in doxorubicin delivery to both drug-sensitive and drug-resistant cancer cells. This system is highly promising as a stimulus-responsive biocompatible nanovehicle. Copyright
Reusable resin plug-bound palladium catalysts for organic synthesis
Atrash, Butrus,Reader, John,Bradley, Mark
, p. 4779 - 4782 (2003)
Resin plugs, a unique and conveniently handled form of resin, prepared by sintering high-density polyethylene (HDPE) with pre-functionalised resins, were derivatised and loaded with palladium(0). These 'plugs' were used in the preparation of a Suzuki reaction based library and the removal of allyl ester protecting groups. The 'plugs of catalyst' were easily separated from the reaction mixture and were re-used multiple times with minimal loss of activity.
Synthesis and Reversible Hydration of a Pseudoprotein, a Fully Organic Polymeric Desiccant by Multiple Single-Crystal-to-Single-Crystal Transformations
Mohanrao, Raja,Sureshan, Kana M.
, p. 12435 - 12439 (2018)
A diphenylalanine derivative, N3-Phe-Phe-NHCH2CCH, was designed for topochemical azide–alkyne cycloaddition (TAAC) polymerization. This dipeptide adopted β-sheet arrangement as designed, in its crystals, but the azide and alkyne were not fitly aligned for
β-Sheet to Helical-Sheet Evolution Induced by Topochemical Polymerization: Cross-α-Amyloid-like Packing in a Pseudoprotein with Gly-Phe-Gly Repeats
Hema, Kuntrapakam,Sureshan, Kana M.
, p. 8854 - 8859 (2020)
Protein-mimics are of great interest for their structure, stability, and properties. We are interested in the synthesis of protein-mimics containing triazole linkages as peptide-bond surrogate by topochemical azide-alkyne cycloaddition (TAAC) polymerization of azide- and alkyne-modified peptides. The rationally designed dipeptide N3-CH2CO-Phe-NHCH2CCH (1) crystallized in a parallel β-sheet arrangement and are head-to-tail aligned in a direction perpendicular to the β-sheet-direction. Upon heating, crystals of 1 underwent single-crystal-to-single-crystal polymerization forming a triazole-linked pseudoprotein with Gly-Phe-Gly repeats. During TAAC polymerization, the pseudoprotein evolved as helical chains. These helical chains are laterally assembled by backbone hydrogen bonding in a direction perpendicular to the helical axis to form helical sheets. This interesting helical-sheet orientation in the crystal resembles the cross-α-amyloids, where α-helices are arranged laterally as sheets.
Massive Parallel Catalyst Screening: Toward Asymmetric MCRs
Kusebauch, Ulrike,Beck, Barbara,Messer, Kim,Herdtweck, Eberhardt,Doemling, Alexander
, p. 4021 - 4024 (2003)
(Equation presented) Hundreds of Lewis acid/ligand combinations have been screened for stereochemical induction in the Passerini multicomponent reaction. The combination of titan tetraisopropylate and (4S,5S)-4,5- bis(diphenylhydroxymethyl)-2,2-dimethyldioxolane was found to give enantiomeric excesses between 32% and 42% in several examples. The absolute stereo induction of one example was determined chemically and by means of X-ray crystallography. This comprises the first asymmetric Passerini reaction and the first example of a stereochemical induction in an isocyanide based multicomponent reaction by a chiral Lewis acid.
Highly Stable Zr(IV)-Based Metal-Organic Frameworks for Chiral Separation in Reversed-Phase Liquid Chromatography
Jiang, Hong,Yang, Kuiwei,Zhao, Xiangxiang,Zhang, Wenqiang,Liu, Yan,Jiang, Jianwen,Cui, Yong
supporting information, p. 390 - 398 (2021/01/13)
Separation of racemic mixtures is of great importance and interest in chemistry and pharmacology. Porous materials including metal-organic frameworks (MOFs) have been widely explored as chiral stationary phases (CSPs) in chiral resolution. However, it remains a challenge to develop new CSPs for reversed-phase high-performance liquid chromatography (RP-HPLC), which is the most popular chromatographic mode and accounts for over 90% of all separations. Here we demonstrated for the first time that highly stable Zr-based MOFs can be efficient CSPs for RP-HPLC. By elaborately designing and synthesizing three tetracarboxylate ligands of enantiopure 1,1′-biphenyl-20-crown-6, we prepared three chiral porous Zr(IV)-MOFs with the framework formula [Zr6O4(OH)8(H2O)4(L)2]. They share the same flu topological structure but channels of different sizes and display excellent tolerance to water, acid, and base. Chiral crown ether moieties are periodically aligned within the framework channels, allowing for stereoselective recognition of guest molecules via supramolecular interactions. Under acidic aqueous eluent conditions, the Zr-MOF-packed HPLC columns provide high resolution, selectivity, and durability for the separation of a variety of model racemates, including unprotected and protected amino acids and N-containing drugs, which are comparable to or even superior to several commercial chiral columns for HPLC separation. DFT calculations suggest that the Zr-MOF provides a confined microenvironment for chiral crown ethers that dictates the separation selectivity.
Chiral secondary phosphine oxide pre-ligand and application thereof
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Paragraph 0040-0043, (2021/10/20)
The invention discloses a chiral secondary phosphine oxide pre-ligand and application thereof. The structure of the ligand is as shown in Formula I, where R. 1 . R2 , R3 And R4 Hydrogen, benzyl, substituted alkyl, substituted or unsubstituted aryl. The more preferred structural formula comprises 4 structural general formulas shown in the general formula I in the following formula: I-d, and the formula is shown in the general formula. Based on the designed asymmetric catalytic reaction system, the stability and the easy preparation of the comprehensive test ligand under the hydrocarbon activation condition are synthesized, and finally the chiral secondary oxidation phosphorus precursor with the double functional groups in the oxidation and heating environment is selected. The catalyst formed by the front ligand and the active metal compound has high activity and high selectivity in the reaction of constructing a chiral center, and has the stability.
Topochemical Ene–Azide Cycloaddition Reaction
Khazeber, Ravichandran,Sureshan, Kana M.
supporting information, p. 24875 - 24881 (2021/09/22)
Topochemical reactions, high-yielding solid-state reactions arising from the proximal alignment of reacting partners in the crystal lattice, do not require solvents, catalysts, and additives, are of high demand in the context of green processes and enviro
CONJUGATE OF FLUORESCENT DYE FOR THE VISUALIZATION OF PSMA EXPRESSING CELLS
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Page/Page column 10; 15, (2021/01/23)
The invention relates to the field of organic and medicinal chemistry, as well as molecular biology, and concerns a new class of compounds for imaging PSMA expressing cells and tissues, such as prostate cancer cells. New diagnostic conjugates for the visu
