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430 results on '"Groth, Ulrich"'

12. Enantiomeric degradation of 2-(4-sulfophenyl)butyrate via 4-sulfocatechol in Delftia acidovorans SPB1

Author

Schulz, Saskia, Dong, Wenbo, Groth, Ulrich, and Cook, Alasdair M.

Subjects
Microbiological research -- Analysis, Enantiomers -- Research, Bacteria -- Research, Biodegradation -- Analysis, Carbon -- Analysis, Biological sciences
Abstract

Research has been conducted on the degradative bacterium Delftia acidovorans SPB1. Experiments have demonstrated that this bacterium utilizes enantiomers sequentially.

Published
2000

13. Tuning of chemo- and regioselectivities in multicomponent condensations of 5-aminopyrazoles, dimedone, and aldehydes

Author

Chebanov, Valentin A., Saraev, Vyacheslav E., Desenko, Sergey M., Chernenko, Vitaliy N., Knyazeva, Irina V., Groth, Ulrich, and Glasnov, Toma N.

Subjects
Aldehydes -- Chemical properties, Condensation -- Analysis, Ketones -- Chemical properties, Pyrazoles -- Chemical properties, Quinoline -- Chemical properties, Biological sciences, Chemistry
Abstract

The three-component condensation of 5-aminopyrazoles, aromatic aldehydes, and cyclic 1,3-diketones to selectively obtain three distinct reaction products, pyrazolo[3,4-b]quinolin-5-ones, pyrazolo[5,1-b]quinazolin-8-ones, and pyrazolo[4,3-c]quinolizin-9-ones is presented. The tricyclic heterocycles could give moderate to good isolated yields.

Published
2008

14. Single-molecule magnets: a new approach to investigate the electronic structure of [Mn.sub.12] molecules by scanning tunneling spectroscopy

Author

Burgert, Michael, Voss, Sonke, Herr, Simon, Fonin, Mikhail, Groth, Ulrich, and Rudiger, Ulrich

Subjects
Organometallic compounds -- Atomic properties, Scanning tunneling microscopy -- Technology application, Monomolecular films -- Properties, Tunneling spectroscopy -- Technology application, Technology application, Chemistry
Abstract

A new approach for the deposition of [Mn.sub.12] single-molecule magnet monolayers on different surfaces is discussed. The study also explains the electronic structure and magnetic properties of the compounds.

Published
2007

19. Electronic transport properties and orientation of individual Mn12 single-molecule magnets

Author

Voss, Sönke, Burgert, Michael, Zander, Ole, Fonin, Mikhail, Rüdiger, Ulrich, and Groth, Ulrich

Subjects
ddc:530, Condensed Matter::Mesoscopic Systems and Quantum Hall Effect
Abstract

Individual Mn12 single-molecule magnets have been investigated by means of scanning tunneling spectroscopy at room temperature. Current-voltage characteristics of a Mn12 derivative are studied in detail and compared with simulations. A few-parameter scalar model for ballistic current flow through a single energy level is sufficient to describe the main features observed in scanning tunneling spectra of individual Mn12 molecules and offers a deeper insight into the electronic transport properties of this class of single-molecule magnets. In addition, distance-voltage spectroscopy performed on individual Mn12 molecules reveals a possibility to identify the orientation of the molecular easy axis. The results indicate a preferential orientation of the easy axis of the molecules nearly perpendicular to the surface.

Published
2008

20. The unsubstituted ortho-amidino benzoic acid: crystal structure, characterization and p K determination.

Author

Hordiyenko, Olga, Biitseva, Angelina, Kostina, Yuliya, Zubatyuk, Roman, Shishkin, Oleg, Groth, Ulrich, and Kornilov, Mikhail

Subjects
BENZOIC acid, CRYSTAL structure, BENZENEDICARBONITRILE, NUCLEAR magnetic resonance, HYDROGEN bonding
Abstract

The simplest o-amidino benzoic acid-2-(amino(imino)methyl)benzoic acid-has been isolated in 23 % yield as a side product of the reaction of phthalonitrile and ammonia along with desired 1-imino-1 H-isoindol-3-amine. This amidino acid was fully characterized by nuclear magnetic resonance, IR spectroscopy, mass spectrometry; pK values were also determined. X-ray diffraction study and quantum chemical calculations revealed that in the solid state it exists as a zwitterion that is stabilized by intermolecular hydrogen bonds. [ABSTRACT FROM AUTHOR]

Published
2017
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25. On alkylideneamidosulfenyl chlorides and 1-Thia-2-azoniaallene salts

Author

Wirschun, Wolfgang G., Hitzler, Martin G., Jochims, Johannes, and Groth, Ulrich

Subjects
ddc:540
Abstract

X-Ray-diffraction analysis of tBu2CNSCl (4b) revealed an almost linear CNS unit with an SN bond order of ca. 1.9 (Fig. 1), in agreement with the structure of a 1-thia-2-azoniaallene chloride. With SCl2 and SbCl5, compound 4b was transformed into the imidosulfurous dichloride 6 (Scheme 2). With morpholine, compounds 4b and 6 afforded the sulfenamide 7and the aminosulfonium salt 8, respectively. The (diarylmethylene)amidosulfenyl chlorides 4g,h,i reacted with SbCl5 to give SbCl salts of the 1,2-benzisothiazoles 9a,b,d, most likely via 1-thia-2-azoniaallene intermediates 2 (Scheme 3).

Published
2002

45. Alpha-Thioalkylation of Zinc Dienolates to 4-Substituted 1-tert-Butoxy-7a-methyl-hexahydroinden-5-ones

Author

Groth, Ulrich, Köhler, Thomas, and Taapken, Thomas

Subjects
thioalkylation of / Indenes / Steroids, ddc:540, Zinc dienolates
Abstract

α-Alkylation of the α,β-unsaturated ketone 1 at C-4 has been achieved by thioalkylation of the corresponding zinc dienolate with α-chlorosulfides of type 2. The desulfurization of the β-(phenylthio) ketones 4 leads directly to the 4-substituted hexahydroinden-5-ones 5.

Published
1994

46. Synthesis of (±)-Chokol A by a Tandem Michael-Addition/Dieckmann Cyclization

Author

Groth, Ulrich, Halfbrodt, Wolfgang, Köhler, Thomas, and Kreye, Paul

Subjects
Chokol A, Terpenes, ddc:540, Tandem reactions, Cyclopentanes, Organometallic reagents, Antifungal agents
Abstract

A total synthesis of (±)-chokol A (rac-12) was accomplished in five steps by starting from the α,β-unsaturated ester (E)-2 in an overall yield of 24%. The key step of this synthesis is the tandem conjugate addition/Dieckmann cyclization of the cuprate derived from vinyl bromide 9 with the α,β-unsaturated ester (E)-2.

Published
1994

47. Addition of Cerium Reagents Derived from (Trimethylsilyl)propargyl Bromide to Aldehydes

Author

Eckenberg, Peter, Köhler, Thomas, and Groth, Ulrich

Subjects
1,7-Octadiynes, ddc:540, substituted, Cerium Compounds, Allenes, Stereoids
Abstract

The addition of (trimethylsilyl)propargylmagnesium bromide (9) to aldehydes afforded predominantly the allenylic alcohols rac-10. The regioselectivity of this addition changes dramatically when organocerium reagents were used for the addition. In this case nearly exclusive formation of the homopropargylic alcohols rac-8 was observed. Highest selectivity for this process was obtained when cerium(III) isopropoxide (13) was used as a precursor for the formation of the organocerium reagent.

Published
1994

48. Alpha-Alkylidenecyclopentanones by Alpha-Alkylidation of Methyl 2-Oxocyclopentanecarboxylate

Author

Arnecke, Ralf, Köhler, Thomas, and Groth, Ulrich

Subjects
ddc:540, thioalkylation of / Cyclopentanones, Zinc enolates, Alpha-alkylidene
Abstract

An α-alkylidation of cyclopentanone was achieved in two reaction steps in an overall yield of 20 to 79% via a zinc chloride-catalyzed thioalkylation of the zinc enolate of methyl 2-oxocyclopentanecarboxylate (3) and subsequent saponification/desulfurization of the β-(phenylthio) ketone intermediates 5. For the saponificatioddesuiurization step DABCO proved to be the reagent of choice and superior to the use of alkali or magnesium halides.

Published
1994

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