-
[show abstract]
[hide abstract]
ABSTRACT: Substituted aminotroponimines, {R-ATI(iPr)2}H (R = Br, I, PhN2, NO2, PhS, PhSe, PhTe, 3,5-(CF3)2C6H3S, PhS(O)), bearing different functional groups in the 5-position were prepared. Reaction of these compounds with ZnMe2 in toluene at 0 °C delivered the corresponding methyl zinc complexes [{R-ATI(iPr)2}ZnMe] in high yields. The solid state structures of four selected examples were established via single-crystal X-ray diffraction analysis. In all compounds the zinc atoms are coordinated in a trigonal-planar fashion. All complexes were investigated as catalysts in the intramolecular hydroamination of non-activated alkenes. The attachment of electron-withdrawing groups in the 5-position such as nitro-or sulfoxide decreased the activity of the corresponding zinc catalysts. In contrast, donor substituents such as a thioether moiety at the backbone of the ligand increased the stability of the chelate and also rendered the zinc atom more reactive. On the other hand, the 5-brominated compound is very labile under the catalytic conditions used. In order to study the potential of an additional beneficial effect from the steric environment around the zinc atom on both reactivity and stability of the corresponding complexes, a prototypic ligand bearing a 5-phenylsulfanyl substituent at the backbone and two cyclohexyl substituents at the nitrogen atoms, {PhS-ATI(Cy)2}H, and its corresponding zinc complex, [{PhS-ATI(Cy)2}ZnMe], were synthesized.
05/2010;
-
Berichte der deutschen chemischen Gesellschaft 01/2010; 2010(7):1070 - 1081. · 2.94 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The appropriate choice of chiral catalyst and starting materials leads to the synthesis of 1,2-oxazetidin-3-ones by cycloadditions of ketenes with nitroso compounds with very good regioselectivity and enantioselectivity. In addition to serving as potentially bioactive target molecules, the products can be transformed into other important classes of compounds, such as alpha-hydroxycarboxylic acid derivatives.
Angewandte Chemie International Edition 03/2009; 48(13):2391-3. · 13.45 Impact Factor
-
Berichte der deutschen chemischen Gesellschaft 02/2009; 2009(10):1369 - 1375. · 2.94 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The electronically modified zinc complex 5-phenylsulfanyl-N-isopropyl-2-(isopropylamino)troponiminate zinc methyl, [(PhS-ATI(iPr)2)ZnMe], was synthesized. It showed an increased reactivity in the intramolecular hydroamination reaction of non-activated alkenes compared to a previously-reported, non-substituted complex.
Dalton Transactions 07/2008; · 3.84 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A series of symmetrical and unsymmetrical N,N'-disubstituted aminotroponimines (ATIHs) have been prepared. Substituents ranging from linear to cyclic alkyl groups, chelating ethers, and aryl groups were employed. The corresponding aminotroponiminate zinc complexes were then synthesized and characterized by a number of techniques, including by X-ray crystallography. Herein we report on the investigations into their activity in the intramolecular hydroamination of nonactivated alkenes. We also demonstrate that complexes bearing ligands with cyclic alkyl groups show superior activity in a number of selected reactions with functionalized aminoalkenes.
Chemistry 02/2007; 13(23):6654-66. · 5.93 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The new zinc compound N-cyclohexyl-2-(cyclohexylamino)troponiminate zinc methyl, [(Cy)2ATI]ZnMe, was synthesized and showed a superior reactivity in the intramolecular hydroamination reaction of non-activated alkenes compared to previously reported homogeneous zinc complexes.
Chemical Communications 09/2006; · 6.17 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: The dimeric complexes 2-(isopropylamino)troponate zinc methyl and ethyl [(iPrAT)Zn-R]2 (R = Me (2a), Et (2b)) were synthesized by reaction of (iPrAT)H with dimethyl and diethyl zinc, respectively, in toluene at low temperature. Reacting (iPrAT)H with dimethyl zinc at elevated temperature resulted in the double-substituted complex [(iPrAT)2Zn] (3). Compounds 2a,b, which were investigated by single-crystal X-ray diffraction, are dimeric in the solid state. The metal centers are bridged asymmetrically by two (μ)-oxygen atoms; thus a flat Zn−O−Zn‘−O‘ plane is observed. Compounds 2a,b were used as the catalyst in the intramolecular hydroamination reaction of nonactivated terminal aminoolefins and one aminoalkyne. Good catalytic activities at elevated temperature were observed.
06/2006;
-
[show abstract]
[hide abstract]
ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
ChemInform 03/2006; 37(13).
-
Angewandte Chemie International Edition 01/2006; 44(47):7794-8. · 13.45 Impact Factor
-
Angewandte Chemie International Edition 03/2004; 43(8):1017-21. · 13.45 Impact Factor
