Search results for "Aminolysis"
showing 10 items of 24 documents
Untersuchungen zur Reaktionsfähigkeit statistisch verteilter Estergruppierungen in Copolymeren aus Styrol und Acrylsäureestern
1974
Die Aminolyse der ortho- und para-Nitrophenylester von Propionsaure, Isobuttersaure, 4-Phenylbuttersaure und 4-Phenylvaleriansaure sowie von Copolymeren aus Styrol und geringen Mengen Acrylsaure wurde mit Butylamin in Dioxan untersucht. Bei grosem Aminuberschus reagieren die niedermolekularen Ester streng nach erster Ordnung, wobei die Reaktionsgeschwindigkeit durch Zugabe von Polystyrol nicht beeinflust wird. Fur Copolymere, deren Reaktionsgeschwindigkeit deutlich geringer ist, erhalt man dagegen keine Beziehung erster Ordnung, obwohl die Anfangsgeschwindigkeit der Gesamtkonzentration der Estergruppen direkt proportional ist. Bei den Copolymeren erhalt man annahernd die gleichen Aktivierun…
Aminolysis of monoacetyl derivatives of 2,2′ -dihydroxydiphenylmethanes
1974
A neighboring group effect was found for the aminolysis of the second acetyl group in acetates of 2,2′-dihydroxydiphenylmethane derivatives containing a nitrophenol and a methylphenol unit. Kinetic measurements with an excess of n-butylamine in dioxane were done with 2-(2-hydroxy-3, 5-dinitrobenzyl)-4-methylphenyl acetate (1), 2-(2-hydroxy-5-nitro-benzyl)-4-methylphenyl acetate (2), and 2-(2-hydroxy-3-nitro-5-methylbenzyl)-4-methyl-phenyl acetate (3). The maximum rate was found for compound 2. When the concentration of n-butylamine was varied over a large range, the results obtained for compound 2 could be explained best, by assuming that the acetyl group in the methylphenol unit is aminoli…
The Crosstalk Between Signaling Pathways and Cancer Metabolism in Colorectal Cancer.
2021
Colorectal cancer (CRC) is one of the most frequently diagnosed cancers worldwide. Metabolic reprogramming represents an important cancer hallmark in CRC. Reprogramming core metabolic pathways in cancer cells, such as glycolysis, glutaminolysis, oxidative phosphorylation, and lipid metabolism, is essential to increase energy production and biosynthesis of precursors required to support tumor initiation and progression. Accumulating evidence demonstrates that activation of oncogenes and loss of tumor suppressor genes regulate metabolic reprogramming through the downstream signaling pathways. Protein kinases, such as AKT and c-MYC, are the integral components that facilitate the crosstalk bet…
Blends of polyamide 6 and bisphenol-A polycarbonate. Effects of interchange reactions on morphology and mechanical properties
1992
Blends of polyamide 6 (PA6) and polycarbonate (PC) were prepared in a Brabender mixer, at 240°C, applying long mixing time, for 45 min. It was observed that the morphology and the mechanical properties tend to resemble those of a homogeneous material as the mixing time and PA6 concentration increase. This is attributed to chemical reactions taking place between the two homopolymers. Acidolysis, amidolysis, and aminolysis, catalyzed by the terminals and the amide groups of the polyamide, should in principle be possible. Our results indicate that the aminolysis is the main process, inducing simultaneously scission of PC chains and formation of PC-PA6 copolymer chains. The latter act as interf…
Pentafluorophenyl Ester-based Polymersomes as Nanosized Drug-Delivery Vehicles
2015
In this work, activated ester chemistry is employed to synthesize biocompatible and readily functionalizable polymersomes. Via aminolysis of pentafluorophenyl methacrylate-based precursor polymers, an N-(2-hydroxypropyl) methacrylamide (HPMA)-analog hydrophilic block is obtained. The precursor polymers can be versatile functionalized by simple addition of suitable primary amines during aminolysis as demonstrated using a fluorescent dye. Vesicle formation is proven by cryoTEM and light scattering. High encapsulation efficiencies for hydrophilic cargo like siRNA are achieved using dual centrifugation and safe encapsulation is demonstrated by gel electrophoresis. In vitro studies reveal low cy…
Synthese von geschützten Serin-Glycopeptiden durch N-terminale Peptidketten-Verlängerung
1983
O-(2-Acetamido-3,4,6-tri-O-acetyl-2- desoxy-β-D-glucopyranosyl)serin-methylester (4) wird mit den 2-Phosphonioethoxycarbonyl-(Peoc-)Aminosauren 5 zu den voll geschutzten O-Glycodipeptiden 6 umgesetzt. Aus den Verbindungen 6 wird die Peoc-Gruppe mit Morpholin/Methylendichlorid vollstandig und selektiv zu 7 abgespalten, wobei weder β-Eliminierung des Kohlenhydratteils noch Esteraminolyse zu beobachten ist. Die N-deblockierten Glycodipeptide 7 reagieren mit den Peoc-Aminosauren 5 zu den geschutzten O-Glycotripeptiden 8. Mit Z-Asparagin (9) kann der Leucyl-(O-glycosyl)serinester 7a zum geschutzten Glycotripeptid 10 verknupft werden, das die fur N-Glycoproteine typische Sequenz -Asn-X-Ser- entha…
Diastereoselective Michael Addition of (S)-Mandelic Acid Enolate to Nitroalkenes. Enantioselective Synthesis of α-Hydroxy-α,β-diaryl-γ-lactams.
2004
Abstract The reaction of the lithium enolate of the ( S , S )- cis -1,3-dioxolan-4-one derived from optically active ( S )-mandelic acid and pivalaldehyde with several aromatic nitroalkenes in the presence of HMPA proceeds readily to give the corresponding Michael adducts in good yields and diastereoselectivities. Reduction of the nitro group with Zn/HCl/EtOH/H 2 O with concomitant intramolecular aminolysis of the acetal moiety leads directly to enantiomerically pure α-hydroxy-α,β-diaryl-γ-lactams.
ChemInform Abstract: Ring-Opening Aminolysis of Sesquiterpene Lactones: An Easy Entry to Bioactive Sesquiterpene Derivatives. Synthesis of (+)-β-Cype…
2010
Abstract Santonin ( 1 ) and other sesquiterpene lactones ( 2–3 ) react with pyrrolidine and other cyclic secondary amines to afford γ-hydroxyamides, which by elimination with mesyl chloride in pyridine-benzene at 80°C give unsaturated amides 4a-4c, 5a-5c and 6 . Starting from amides 5a-5c a series of bioactive compounds against Locusta migratoria have been prepared, differing in the oxidation states of the C-3 and C-12 carbon atoms. Starting from amides 5a and 6 two conjugated diene eudesmanes (+)-β-cyperone ( 15 ) and (−)eudesma-3,5-diene ( 19 ) have been prepared involving an elaboration of the amide group of the side chain of the eudesmane skeleton.
A non-catalyzed ring-opening aminolysis reaction of sesquiterpene lactones
1994
Abstract Santonin (1) and other sesquiterpene lactones (6–10) react cleanly with pyrrolidine at room temperature to afford γ-hydroxyalkylamides, which by elimination with mesyl chloride in pyridine-benzene at 80°C give unsaturated alkylamides.
Synthesis and biopharmaceutical characterisation of new poly(hydroxyethylaspartamide) copolymers as drug carriers.
2001
Abstract Four new poly(hydroxyethylaspartamide)-based copolymers bearing (a) poly(ethylene glycol) 2000, (b) poly(ethylene glycol) 5000, (c) poly(ethylene glycol) 2000 and hexadecylalkyl, (d) poly(ethylene glycol) 5000 and hexadecylalkyle, as pendant groups were synthesised. The copolymers were obtained by partial aminolysis of polysuccinimide with poly(ethylene glycol) and hexadecylalkyl amino derivatives followed by reaction with ethanolamine. Naked polyhydroxyaspartamide was obtained by polysuccinimide reaction with ethanolamine. The nuclear magnetic resonance, infrared, light scattering and elemental analysis allowed for the extensive physico-chemical characterisation of the carriers. T…