Search results for "None"
showing 10 items of 1921 documents
Enzymatic Resolution of 3-oxodicyclopentadiene on a Decagram Scale
2018
The chiral building block 3-oxodicyclopentadiene (1) can be readily resolved on a decagram scale by a short sequence consisting of (1) reduction to the corresponding endo-alcohol, (2) enzymatic oxidative resolution with a ketoreductase enzyme to give (+)-1 and the (+)-form of the endo-alcohol, and (3) reoxidation of the (+)-endo-alcohol with another ketoreductase to give (–)-1. With a selectivity factor of 310, the enantiomeric ratios of the resolved (+)-endo-alcohol and (+)-ketone are both >99:1. Both enzymatic oxidations could be performed with a at least 300:1 substrate/catalyst ratio (w/w).
Photocrosslinkable dextran hydrogel films as substrates for osteoblast and endothelial cell growth
2012
Functional hydrogel films on solid supports are versatile materials with large potential for cell growth and tissue engineering. Here, we report on a modular approach to generate functional hydrogel composite films for endothelial and osteoblast cell co-culture. The polymer network of the parent hydrogel was formed by a dextran derivative (BP-CMD), which contained carboxymethyl (CM) groups for further chemical functionalization and benzophenone (BP) moieties as a photocrosslinkable unit. BP-CMD could be synthesized by three different routes, first with the benzophenone unit attached via an amide bond, or second by an ether bond, or third as an ion pair between the benzophenone ammonium salt…
Studien zum Vorgang der Wasserstoffübertragung, 47.Elektroreduktion von 1,4-Benzoldicarbonitril, 1,4-Diacetylbenzol und Terephthalaldehyd
1978
Die Elektroreduktion von 1,4-Benzoldicarbonitril in Gegenwart von Essigsaure fuhrt bei einem Stromdurchgang von 4.5 Faraday-aquivalenten/mol in 80proz. Ausbeute zu 4-Amino-methylbenzonitril (1). Bei Anwendung von 6 Faraday-aquivalenten/mol konnen geringe Mengen an 4-Methylbenzonitril (2) nachgewiesen werden. Bei der praparativen Elektroreduktion von 1,4-Diacetylbenzol in Gegenwart unterschiedlicher Mengen an Essigsaure entstehen 4-(1-Hydroxyethyl)acetophenon (3), 1,1′-(1,4-Phenylen)diethanol (4) sowie polymere Pinakole 5 in den in Tabelle 1 angegebenen Mengen. Terephthalaldehyd wird in Gegenwart von Essigsaure zu 4-Hydroxymethylbenzaldehyd (6), Terephthalalkohol (7) und einem polymeren Pina…
Über die Synthese von o-Acylamino-ß-dimethylamino-propiophenonen 1. Mitt.: Verhalten von o-Nitro- und o-Carbäthoxyamino-acetophenon bei der Mannich-R…
1970
Das bei der Mannich-Reaktion von o-Carbathoxyamino-acetophenon mit Paraformaldehyd und Dimethylamin-hydrochlorid erhaltene Kondensationsprodukt wurde als ein Gemisch von o-Carbathoxyamino-β-dimethylamino-propiophenon und o-Carbathoxyamino-α-dimethylaminomethyl-acrylophenon identifiziert. Durch Variation der Versuchsbedingungen konnte das Acrylophenonderivat als Hauptprodukt erhalten werden. Es war durch Saurekatalyse in 1-N-Carbathoxy-3-dimethylaminomethyl-4-oxo-1,2,3,4-tetrahydrochinolin uberfuhrbar. Synthesis of o-Acylamino-β-dimethylamino-propiophenones The aminomethylation product of o-carbethoxyamino-acetophenone, paraformaldehyde and dimethylamine-hydrochloride was identified as a mix…
Proton Acid-induced Rearrangements of α-Alkynylestradiol Methyl Ethers
1993
When subjected to proton catalysis, the α-alkynylestradiol methyl ethers 1a and 1b furnish the Rupe or Meyer-Schuster rearrangement products 2, 4, and 5a. In the presence of sulfuric acid, α-ethynylestradiol 3-methyl ether (1a) is converted into the D-homosteroid 3a. The use of deuterated acids gives rise to the formation of the corresponding deuterated steroids 2b, 2c, 3b, and 5b. Some mechanistic implications of these results are also discussed.
Über die Synthese von o-Acylamino-β-dimethylamino-propiophenonen 2. Mitt.: Aminomethylierung von o-Carbäthoxyamino- und o-Nitro-acetophenon1)
1970
Die bei der Mannich-Reaktion mit o-Carbathoxyamino- und o-Nitro-acetophenon zu Acrylophenonderivaten fuhrende Sekundarreaktion zwischen den Aminomethylierungsprodukten und Formaldehyd konnte auf folgende Weise nahezu vollstandig vermieden werden: durch Verhindern des Zerfalls von intermediar entstehendem Dimethylaminomethylol in seine Komponenten wird die Bildung des Carbonium-Imonium-Kations derart beschleunigt, das fur die Nebenreaktion erforderlicher freier Formaldehyd rasch aus dem Reaktionsmedium verschwindet. — Die Synthese von o-Carbathoxyamino-, o-Nitro- und o-Amino-β-dimethylamino-propiophenon sowie seines Formyl- und Acetylderivates wird beschrieben. Synthesis of o-Acylamino-β-dim…
Cyclic esters of aliphatic diacids with pyrocatechol and hydroquinone
1985
Cyclic esters of adipic acid, suberic acid and sebacic acid were prepared by reaction of the acid dichlorides and pyrocatechol or hydroquinone in benzene under high dilution conditions. While only the cyclic dimers could be obtained from hydroquinone, pyrocatechol formed cyclic monomers as well as cyclic dimers (and also a cyclic dimer with succinic acid). The structure of all compounds was confirmed by1H-NMR- and mass spectra. The crystal structures of the pyrocatechol esters were determined by single crystal X-ray analysis.
Zearalenone presence in wheat field samples from Romania
2016
Comparative cytotoxicity effect of zearalenone and its metabolites on the CHO-K1 cells
2009
ChemInform Abstract: Light Induced C-C Coupling of 2-Chlorobenzazoles with Carbamates, Alcohols, and Ethers.
2016
A light induced, transition-metal-free C-C coupling reaction of 2-chlorobenzazoles with aliphatic carbamates, alcohols, and ethers is presented. Inexpensive reagents, namely sodium acetate, benzophenone, water, and acetonitrile, are employed in a simple reaction protocol using a cheap and widely available 25 W energy saving UV-A lamp at ambient temperature.