Search results for "imide"

Heterotelechelic Ring-Opening Metathesis Polymers

2009

By combining sacrificial synthesis with the vinyl lactone termination technique, heterotelechelic polymers were synthesized. The nonterminating nature of sacrificial synthesis was utilized to introduce a hydroxyl group at the start of the polymer chain. Lactone termination was used to functionalize the chain ends with aldehydes or carboxylic acids. The synthesis of well-defined heterotelechelic polymers was thus accomplished employing the Grubbs’ first generation catalyst as the initiator. The living nature of this polymerization allowed for precise control over the molecular weight and guaranteed full functionalization of both polymer chain ends. The presence of the functional groups is sh…

Sacrificial Synthesis of Hydroxy-Telechelic Metathesis Polymers via Multiblock-Copolymers

2009

The synthesis of well-defined telechelic ring-opening metathesis polymers has been achieved by Sacrificial Synthesis. With the formation of cleavable triblock-copolymers, precise control over the molecular weight and the degree of functionalization was achieved. Introducing cleavable monomers that can be addressed separately, sequential deprotection was accomplished which opened the path to more sophisticated polymeric materials bearing different substituents at their respective chain ends. Sacrificial penta- and heptablock-copolymers are also presented which allow the synthesis of well-defined telechelic polymers in good yields and significantly improved initiator efficiency.

1978

Synthesis and characterization of polymeric derivatives of the folic acid antagonist, Methotrexate, N-[4-(N-methyl-2,4-diamino-6-pteridinylmethylamino)benzoyl] glutamic acid (1a), a widely used antitumor agent, are described. Derivatives of poly(L-lysine), poly(iminoethylene), poly(vinyl alcohol), and carboxymethylcellulose with various contents (3–15 mole-%) of substituted repeating units were prepared by polymer-analogous amidation and transesterification of the dimethyl ester of 1a and with N-[2-(N-methylmorpholinio)ethyl]carbodiimide p-toluenesulfonate as coupling reagent. By nucleophilic addition reactions of the pteridinyl amino groups under mild conditions, 1a was bound without cross…

Umwandlung von 2-Bromäthoxycarbonyl-Schutzgruppen in 2-Phosphonioäthoxycarbonyl-Schutzgruppen für Aminosäuren1)

1976

Die Bromide 2 von 2-Phosphonioathoxycarbonylaminosauren (Peoc-Aminosauren) werden durch Umsetzung von 2-Bromathoxycarbonylaminosauren (Beoc-Aminosauren) mit tertiaren Phosphinen erhalten. Hierbei entstehen durch Reaktion mit Methyl(diphenyl)phosphin die mit der modifizierten Peoc-Gruppe geschutzten Verbindungen 2e - h in besonders guten Ausbeuten. Diese eignen sich zur Peptidsynthese nach dem Carbodiimid-Verfahren und sind besser in Wasser loslich als die entsprechenden Triphenylphosphonium-Derivate. Die Abspaltung der Me(Ph2)Peoc-Gruppe gelingt mit 0.01 N NaOH in Methanol/Wasser. Modification of 2-Brornoethoxycarbonyl Protective Groups to 2-Phosphonioethoxycarbonyl Protective Functions of …

Measurement of Protein Synthesis: In Vitro Comparison of 68Ga-DOTA-Puromycin, [3H]Tyrosine, and 2-Fluoro-[3H]tyrosine

2012

Aim: Puromycin has played an important role in our understanding of the eukaryotic ribosome and protein synthesis. It has been known for more than 40 years that this antibiotic is a universal protein synthesis inhibitor that acts as a structural analog of an aminoacyl-transfer RNA (aa-tRNA) in eukaryotic ribosomes. Due to the role of enzymes and their synthesis in situations of need (DNA damage, e.g., after chemo- or radiation therapy), determination of protein synthesis is important for control of antitumor therapy, to enhance long-term survival of tumor patients, and to minimize side-effects of therapy. Multiple attempts to reach this goal have been made through the last decades, mostly u…

A new access to 2′-amino-substituted vinylindoles as donor-activated heterocyclic dienes and their first diels-alder reactions

1992

Abstract Reactions of the 3-acylindoles 5, 10 , and 15 with α-amino-α′-diphenylphosphinoyl-substituted carbanions gave rise to the 2′-amino-substituted 3− and 2-vinylindoles 7, 12 , and 17 by way of the isolable carbinols 6 , 11 , and 16 . The heterocyclic dienes 7 , 12 , and 17 readily underwent Diels-Alder reactions with N -phenylmaleimide.

Untersuchungen zu einem modell der herstellung von oligopeptiden mittels einer synthetischen matrizenreaktion

1970

Aktivierte Ester von Carbobenzoxyaminosauren mit drei phenolischen Zweikernverbindungen wurden dargestellt. Die anhydridmethode unter Verwendung von Chlorameisensaureathylester stellte sich dabei als gunstiger heraus als die Carbodiimidmethode unter Verwendung von Dicyclohexylcarbodiimid. Dies mag durch sterische Grunde bedingt sein. Uber gemischte Anhydride gelang auch die Verlangerung von Aminosaureestern zu Dipeptidestern. Die Ester von phenolischen Mehrkernverbindungen mit Aminosauren oder Peptiden konnen zur Darstellung von Oligopeptiden benutzt werden. Diese Reaktionsfolge, die als Modell einer Matrizenreaktion betrachtet werden kann, wurde an ihrem einfachsten Beispiel untersucht. Ac…

Synthesis of 1H-imidazo[3′,4′:4,5]thieno[2,3-b]pyridines. A new ring system

1984

A facile and convenient synthesis of the title compounds is described, using as starting materials the 2-nitro-3-aminothieno[2,3-b]pyridines. Mass spectral data of the above mentioned compounds are briefly discussed.

Struktur-Wirkungs-Beziehungen bei Analeptica vom Typ des Nicethamids, 3. Mitt. Synthese von Analogen des 6-Methyl-nicethamids

1975

Als potentiell analeptisch wirksame Substanzen mit partiell fixierter funktioneller Gruppe werden strukturanaloge Amide, Imide und Lactame des 2-Methyl-nicethamids synthetisiert. Synthesis of 2-Methyl-Nicethamide Analogues. As potentially analeptically active substances with partially fixed functional groups, structural analogues of 2-methyl-nicethamide, in the form of amides, imides and lactams, are synthesized.

Cation-induced self-assembly of an amphiphilic perylene diimide derivative in solution and Langmuir–Blodgett films

2015

Abstract A novel amphiphilic perylenetetracarboxylic diimide (PDI) derivative, N-(4′-benzo-15-crown-5-ether)-N-hexyl-1,7-di(4-tert-butyl-phenoxy)perylen-3,4,9,10-tetracarboxylic diimide (15C5PDI), has been synthesized and characterized. Dimerization of 15C5PDI is induced in CHCl 3 solution with the present of K + , resulting in the formation of the slipped co-facial J -aggregates, as revealed by absorption and fluorescence spectroscopies. Analysis of the surface pressure–area ( π – A ) isotherms and spectral change for the monolayer formed at the air/water interface, disclosed that 15C5PDI molecules adopted the H -type aggregation mode with a face-to-face configuration and edge-on orientati…