ZfN: Search Results

1	Author	Henri Brunner, A.F M Mokhlesur Rahman	Requires cookie*
	Title	Asymmetrische Katalysen, 13 [1] Chelat-Liganden und ihre Rhodium-Komplexe mit seitlichen Asymmetriezentren und ihre Anwendung in der enantioselektiven Katalyse Asymmetric Catalyses. 13 [1] Chelate Ligands and their Rhodium Complexes with Lateral Asymmetrie Centers and their Use in Enantioselective Catalysis
	Abstract	The chelate ligands 1-3 with lateral asymmetric centers at the nitrogen atoms were prepared and characterized. In the Rh complexes 4 and 5 the asymmetric centers directly interact with those coordination positions where during enantioselective catalysis pro-chiral substrates are converted into optically active products. The compounds 4 and 5, as well as the in situ catalysts [Rh(COD)Cl]2/2 were used in the asymmetric hydrogenation of a-N[acetamino]cinnamic acid and in the asymmetric hydrosilylation of acetophenone with diphenylsilane. The low optical inductions obtained result from the catalyst loosing its chiral information during catalysis due to racemization or fragmentation.
	Reference	Z. Naturforsch. 38b, 1332—1338 (1983); eingegangen am 16. Mai 1983
	Published	1983
	Keywords	Optical Activity, Asymmetrie Induction, Enantioselective Catalysis
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	TEI-XML for	default:Reihe_B/38/ZNB-1983-38b-1332.pdf
	Identifier	ZNB-1983-38b-1332
	Volume	38

2	Author	Enantioselective Catalysis, New Expanded, Chiral Bipyridines, Henri Brunner, Ingo Poleschak	Requires cookie*
	Title	Enantioselektive Katalyse, 109 [1] Neue erweiterte chirale Bipyridine
	Abstract	Optically active two and three layer nitrogen ligands were synthesized by reacting the N-BOC-protected aminoalcohols (lS,2S)-2-am ino-l -phenyl-1,3-propanediol and (S)-2-amino-1,4-butanediol with chloromethyl-benzoic acid chlorides. Expansion was carried out at the chlo-romethyl substituents via nucleophilic substitution with N-methylated (R)-l-phenylethylamine. The deprotected substances were N-benzylated and reacted with 6,6'-bis(bromomethyl)-2,2'-bipyridine to give the new optically active expanded bipyridine ligands.
	Reference	Z. Naturforsch. 52b, 839—846 (1997); eingegangen am 27. März 1997
	Published	1997
	Keywords	Optically Active Ligands, Enantioselective Catalysis, Expanded Bipyridine Ligands
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	TEI-XML for	default:Reihe_B/52/ZNB-1997-52b-0839.pdf
	Identifier	ZNB-1997-52b-0839
	Volume	52

3	Author	Andreas Ketter, R. Udolf, Herrmann, GarchingF R G	Requires cookie*
	Title	Chiral Lewis Acids as Enantioselective Catalysts in the Diels-Alder Reaction and the Allylic Addition to Aldehydes
	Abstract	The efficiency o f chiral Lewis acids derived from TiCl4 or A1(Bu/)2C1 with chiral chelating ligands as catalysts for som e enantioselective reactions was evaluated. The Diels-Alder reac tion between isoprene and methyl acrylate gave the cyclohexene derivative with up to 32% enantiomeric excess (e.e.). The reaction o f 3-methylbutanal with allyltrimethylsilane led to 6-m ethylhept-l-en-4-ol with up to 36% e.e.
	Reference	Z. Naturforsch. 45b, 1684—4 (1990); received June 11 1990
	Published	1990
	Keywords	Chiral Lewis Acids, Allylic A ddition, Enantioselective Catalysis, Diels-Alder Reaction
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	TEI-XML for	default:Reihe_B/45/ZNB-1990-45b-1684.pdf
	Identifier	ZNB-1990-45b-1684
	Volume	45