Bremen, Germany
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Sevenard D.V.,Hansa Fine Chemicals GmbH | Didenko A.V.,Hansa Fine Chemicals GmbH | Lorenz D.,Hansa Fine Chemicals GmbH | Vorobiev M.,Hansa Fine Chemicals GmbH | And 3 more authors.
Tetrahedron | Year: 2017

A simple and reliable method for the preparation of 2,2-dimethyl-5-(trifluoroacetyl)-1,3-dioxane-4,6-dione and 2,2-dimethyl-6-(trifluoromethyl)-4H-1,3-dioxin-4-one on a multigram scale was developed. These (trifluoroacetyl)ketene precursors were used in the hetero-Diels-Alder reaction with dialkylcyanamides and 1-ethoxyprop-1-yne, as well as in some reactions with nucleophiles. © 2017 Elsevier Ltd


Rindzevicius T.,Technical University of Denmark | Barten J.,Hansa Fine Chemicals GmbH | Vorobiev M.,Hansa Fine Chemicals GmbH | Schmidt M.S.,Technical University of Denmark | And 2 more authors.
Vibrational Spectroscopy | Year: 2017

We present an improved procedure for analytical detection of toxic polychlorinated biphenyls (PCB) using surface-enhanced Raman scattering (SERS) spectroscopy. A gold-capped silicon nanopillar substrate was utilized to concentrate PCB molecules within an area of high electromagnetic fields through formation of microsized nanopillar clusters, and consequently, so-called “hot spots” can be formed. In order to improve PCB detection limit, 3,3′,4,4′-tetrachlorobiphenyl (PCB77) compounds were chemically modified with a [sbnd]SCH3 (PCB77-SCH3) group. Experimental and numerical analysis of vibrational modes showed only minor differences between standard PCB77 and PCB77-SCH3. Consequently, we observe significantly increased SERS signals for [sbnd]SCH3 modified PCB77 while retaining most vibrational modes that characterize standard PCB77. Results point towards more efficient path for detecting different PCB congeners from real-life samples. We interpret the result as PCB77[sbnd]SCH3 link to gold surface via sulfur atoms that facilitates accumulation of the modified PCB molecules on the metal surface. For similar SERS experimental conditions most spectral characteristics of PCB77 are identifiable down to concentrations of ∼10−5 M while PCB77[sbnd]SCH3 spectral fingerprint is retained in ∼10−8 M range. © 2017 Elsevier B.V.


Sevenard D.V.,Hansa Fine Chemicals GmbH | Kazakova O.,University of Bremen | Schoth R.-M.,University of Bremen | Lork E.,University of Bremen | Roschenthaler G.-V.,University of Bremen
Journal of Chemical Crystallography | Year: 2011

The crystal structures of 2,5-bis(trifluoroacetyl) cyclohexane-1,4-dione (1) and o,o′-bis(trifluoroacetyl)-p-cresol (2) is reported. The first compound crystallizes in monoclinic space group P2 1/n with a = 6.5040(10), b = 10.1610(10), c = 8.2420(10) Å, β = 91.690(10)° and V = 0.54445(12) nm 3. Double enolization (U-structure) with a considerable electron density delocalization in the enolone backbone was established in this case. Phenol 2 crystallizes in triclinic space group P-1 with a = 7.0690(10), b = 9.4890(10), c = 9.8190(10) Å, α = 103.720(10), β = 110.760(10), γ = 102.150(10)° and V = 0.56598(12) nm 3. In contrast to CDCl 3 solution, a "bifurcate" structure of 2 with jumping OH proton is quenched: only one of both trifluoroacetyl moieties is bonded by intramolecular hydrogen bond. © Springer Science+Business Media, LLC 2011.


Iaroshenko V.O.,University of Rostock | Iaroshenko V.O.,Taras Shevchenko National University | Bunescu A.,University of Rostock | Bunescu A.,Leibniz Institute for Catalysis at the University of Rostock | And 7 more authors.
Journal of Fluorine Chemistry | Year: 2011

A formal [3+3] cyclocondensation of 1,3-bis(silyl enol ethers) with the little-known 4,4-dimethylthio-1,1,1-trifluorobut-3-en-2-one was studied. In contrast to 4,4-dimethoxy-1,1,1-trifluorobut-3-en-2-one, this α-oxoketene dithioacetal reacts with 1,3-bis(trimethylsilyloxy)-1,3-butadienes in the presence of TiCl4 to give mainly 6-methylthio-4-(trifluoromethyl) salicylates via 1,2-addition. The scope and limitations of the reaction are discussed. © 2011 Elsevier B.V. All rights reserved.


Iaroshenko V.O.,University of Rostock | Iaroshenko V.O.,Taras Shevchenko National University | Mkrtchyan S.,University of Rostock | Mkrtchyan S.,Yerevan State University | And 10 more authors.
Tetrahedron | Year: 2012

3-Nitrochromone reacts with electron-rich aminoheterocycles (in glacial acetic acid at reflux) and anilines (in a mixture of DMF and TMSCl at 100-140 °C) to give a variety of hetero(carbo)annulated 3-nitropyridines. The reaction, involving a formal [3+3] cyclocondensation, proceeds in high yields and appears not to be influences greatly by the nature of the 1,3-C,N-dinucleophile as seen from the thorough scope study. The synthetic utility of the products was demonstrated by their conversion into the corresponding 3-aminopyridine derivatives. An NMR study and X-ray crystallographic analysis are reported. © 2012 Elsevier Ltd. All rights reserved.


Sosnovskikh V.Y.,Ural Federal University | Sevenard D.V.,Hansa Fine Chemicals GmbH | Moshkin V.S.,Ural Federal University | Iaroshenko V.O.,University of Rostock | Langer P.,University of Rostock
Tetrahedron | Year: 2010

The reactions of 3-formylthiochromone with o-phenylenediamines, o-aminobenzenethiol, and indoles proceeded at the aldehyde group to give 3-(benzimidazol-2-yl)thiochromone, 3-(benzothiazol-2-yl)thiochromone, and 3-di(indol-3-yl)methylthiochromones, respectively. 3-Formyl- and 3-cyanothiochromones react with primary aromatic amines and phenylhydrazine to give the corresponding anils and phenylhydrazones of 3-formyl- and 2-amino-3-formylthiochromones. The reaction of 3-cyanochromones with o-phenylenediamines gave 2-amino-3-[(2-aminophenyl)iminomethyl]-4H-chromen-4- ones. © 2010 Elsevier Ltd. All rights reserved.


Didenko A.V.,Hansa Fine Chemicals GmbH | Vorobiev M.V.,Hansa Fine Chemicals GmbH | Sevenard D.V.,Hansa Fine Chemicals GmbH | Sosnovskikh V.Ya.,Ural Federal University
Chemistry of Heterocyclic Compounds | Year: 2015

[Figure not available: see fulltext.] Starting from 3-(trifluoromethyl)quinoxalin-2(1H)-one, a wide range of new 2-substituted 3-(trifluoromethyl)quinoxalines were obtained, including amino, bromo, chloro, hydrazino, phenyl, α-furyl, formyl, methylsulfanyl, and methylsulfonyl derivatives. 3-(Tri(di)-fluoromethyl)quinoxaline-2-carboxylic acids were obtained for the first time and used for the synthesis of 2-amino-3-(tri(di)-fluoromethyl)quinoxalines and 2-(2-aminothiazol-4-yl)-3-(trifluoromethyl)quinoxaline. © 2015 Springer Science+Business Media New York.


Barabanov M.A.,Ural Federal University | Sevenard D.V.,Hansa Fine Chemicals GmbH | Sosnovskikh V.Ya.,Ural Federal University
Russian Chemical Bulletin | Year: 2012

Reactions of 1,1,1-trifluoro-4,4-bis(methylthio)but-3-en-2-one with cyanoacetamide, malonamide, acetoacetamide, amidines, hydrazines, and hydroxylamine gave a number of novel trifluoromethylated heterocyclic compounds containing the methylthio group. © 2012 Springer Science+Business Media New York.


Barabanov M.A.,Ural Federal University | Sevenard D.V.,Hansa Fine Chemicals GmbH | Sosnovskikh V.Ya.,Ural Federal University
Russian Chemical Bulletin | Year: 2012

1,4-Nucleophilic addition reactions of 3-nitrothiochromone with indoles gave a number of novel trans-2-(indol-3-yl)-3-nitrothiochroman-4-ones in 36-89% yields. During the reactions, the thiopyrone ring underwent no opening. © 2012 Springer Science+Business Media New York.


Filyakova V.I.,Russian Academy of Sciences | Boltacheva N.S.,Russian Academy of Sciences | Sevenard D.V.,Hansa Fine Chemicals GmbH | Charushina V.N.,Russian Academy of Sciences
Russian Chemical Bulletin | Year: 2010

1,5-Benzo[b]- and 1,5-naphtho[2,3-b]diazepines were synthesized by the reaction of lithium 1,3-diketonates with 1,2-diaminobenzene and 2,3-diaminonaphthalene in an MeOH-AcOH-HCl mixture at 0°C. The reactions of fluoroalkyl-containing lithium 1,3-diketonates with 1,2-diaminobenzene and 1,2-diamino-4,5-difluorobenzene under reflux in acetic acid afford 2-fluoroalkyl-containing benzimidazoles as the major products, whereas the reaction with 2-aminothiophenol gives 2-phenylbenzothiazole. The reactions of lithium diketonate containing the cyclohexane and cyclopentane moieties with 1,2-diaminoarenes and 2-aminobenzenethiol are accompanied by the opening of the carbocycle to form 2-(6-oxo-7,7,7-trifluoroheptyl)benzimidazole and 2-(5-oxo-6,6,6-trifluorohexyl)benzothiazole hydrates, respectively. © 2010 Springer Science+Business Media, Inc.

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