Search results for "Taut"
showing 10 items of 916 documents
N-Heterocyclic carbenes from ylides of indolyl-imidazolium, azaindolyl-imidazolium, and indolyl-triazolium salts, and their borane adducts
2014
Abstract Indol-2-yl-imidazolium salts were deprotonated at N1 of the indole ring to give ylides. Their tautomeric N-heterocyclic carbenes (NHCs) were trapped by sulfur to give imidazole-2-thiones. Treatment of the ylides with triethylborane resulted in the formation of zwitterionic borane adducts. An analogous sequence of reactions was performed with 8-azaindol-2-yl-imidazolium salts, which served as precursor to prepare first representatives of a new heterocyclic ring system on reaction of their NHC-tautomers with triethylborane. Similarly, an indol-2-yl-1,2,4-triazolium salt was examined with respect to ylide–NHC tautomerism and trapping reactions. A nucleophilic ring transformation of in…
Der Zukunftsstaat: Wirtschaftstechnisches Ideal und Volkswirtschaftliche Wirklichkeit
1927
Vierte, vollständig neu bearbeitete Auflage
Latvijas rūpniecības attīstības tendences un perspektīvas
2005
Advisor: Deniņš, Andris
6-Thiopurine complexes of organotin(IV) moieties. Synthesis and structural characterization by infrared and Mössbauer spectroscopy
1982
Abstract The novel complexes Me3Sn(6-TP−1) and Bun2Sn(6-TP−1)2, where 6-TP−1 is the mono-anion of 6-thiopurine, have been synthesized. The sites of stannylation of 6-TP have been inferred from the known directions of electrophilic substitution reactions of 6-TP itself. The compounds have been characterized by infrared and Mossbauer spectroscopy. A solid state polymeric structure has been proposed for Me3Sn(6-TP−1), where planar SnC3 skeletons are bridged by 6-TP−1 (thione tautomer) axially bound to Sn through N(3) and N(1) atoms. For Bun2Sn(6-TP−1)2, a molecular structure has been advanced, with the ‘aromatic’ ligand anions chelating Sn by S-N(7) atoms.
Molecular switching complexes with iron and tin as central atom
2009
Abstract The precursor [Fe III (L)Cl] (LH 2 = N , N ′-bis(2′-hydroxy-benzyliden)-1,6-diamino-3-N-hexane is a high-spin ( S = 5/2) complex. This precursor is combined with the bridging units [Sn IV (X) 4 ] (X = CN − , NCS − ) to yield star-shaped pentanuclear clusters, [(LFe III –X) 4 Sn]Cl 4 . For X = CN − the 57 Fe-Mossbauer data show a multiple spin transition between iron(III) in the high-spin and low-spin state, while the 119m Sn-Mossbauer data indicate a valence tautomerism between Sn(IV) and Sn(II). Changing the bridging unit from X = CN − to X = NCS − turns the switchability off.
Antidiabetische wirkstoffe, IV [1] trifluormethylsubstituierte 2-(4-toluidino)pyrimidine
1985
Zusammenfassung Durch Umsetzung von 4-Tolylguanidin mit den entsprechenden fluorierten β-Diketonen in Gegenwart von Natriumcarbonat im Schmelzfluβ sind die folgenden 4-Trifluormethyl-2-(4-toluidino) pyrimidine zuganglich gemacht worden: die 6-Methyl-, 6-Ethyl-, 6-Isopropyl-, 6-tert. Butyl- und 6-Isopentyl-Abkommlinge. Zur Charakterisierung der dargestellten Verbindungen sind IR-, 1H-NMR- und MS-Daten herangezogen worden. In dem neuen Strukturtyp sind besonders antidiabetische, antimykotische, trichomonazide und herbizide Wirksamkeit ausgepragt.
GIAO/DFT 13C NMR Chemical Shifts of 1,3,4-Thiadiazoles
2007
1 H, 13 C and 15 N NMR spectra of 2-acetylamino-1,3,4-thiadiazole and its 5-substituted derivatives have been measured and assigned based on reference data, as well as homo- and heteronuclear 2 D NMR experiments. In addition, the GIAO/DFT approach at the B3LYP level of theory using the 6-311G basis set was used to calculate the 13 C NMR chemical shifts. Although this method gives reliable results for 2-arylhydrazones of 1,3-diphenylpropanetrione, 2-phenacylpyridines, (Z)-2-(2-hydroxy-2-phenylvinyl)pyridines, 4-fluoroanilines, (1Z,3Z)-1,4-di(pyridin-2-yl)buta-1,3-dienediols and their tautomeric forms, the calculated chemical shifts for the 1,3,4-thiadiazoles studied are less satisfactory. Pr…
Antineoplastika XVI [1]. 4-Alkyl-6-trifluormethyl-2-ureidopyrimidine
1985
Zusammenfassung Bei der Umsetzung von Dicyandiamid mit Trifluormethyl- gruppen tragenden β-Diketonen entstehen die korrespondierenden 4-Alkyl-6-trifluormethyl-2-ureidopyrimidine. So wird mit 1,1,1-Trifluor-2,4-pentandion das 4-Methyl-6-trifluormethyl- 2-ureidopyrimidin, mit 1,1,1-Trifluor-2,4-hexandion das 4- Ethyl-6-trifluormethyl-2-ureidopyrimidin, erhalten. Die Struktur der Endprodukte wird dutch die IR-, 1 H-NMR-, 13 C-NMR- und Massenspektren charakterisiert.
Analyse und Optimierung von Gasphasen‐Reaktionen, 18 1,2) Die Pyrolyse von Methylazid
1981
Die PE-spektroskopisch analysierte Pyrolyse von Methylazid verlauft bei 850 K und liefert als Hauptprodukt Methanimin, welches nach einer MNDO-Singulett-Hyperflache betrachtlich stabiler sein sollte als das tautomere Methylnitren. Analysis and Optimization of Gasphase Reactions, 181,2) The Pyrolysis of Methyl Azide The PE spectroscopically analyzed pyrolysis of methyl azide occurs at 850 K and yields as main product methanimine, which according to a MNDO singlet hypersurface should be considerably stabilized relative to the tautomeric methyl nitrene.
Supramolecular hydrogen-bonding tautomeric sulfonamido-phosphinamides: a perfect P-chirogenic memory
2011
P-chirogenic, supramolecular hydrogen-bonding C1-symmetrical sulfonamido–phosphinamides (METAMORPhos) have been successfully prepared. They were all found to possess a characteristic prototropic equilibrium between the PIII and the PV tautomers that is slow on the NMR spectroscopic timescale. Despite the dynamic and reversible protonation of the P centre, the P-chirogenic information was found to be retained in the tautomerization process, even in a protic solvent environment. Several strategies to access the corresponding enantiopure compounds were investigated, such as diastereoselective crystallization, or enantioselective synthesis. It was possible to resolve such a class of chiral liga…