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  • 1
    ISSN: 0899-0042
    Keywords: optically active aminodiols ; chiral ligands ; enantioselective reaction ; enantiomeric excess ; chiral separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Some 3-t-butyldimethylsilyloxy derivatives, synthesized from the cheap commercially available (1S,2S)-2-amino-1-phenyl-1,3-propanediol [(1S,2S)-1], have been successfully employed as new chiral ligands in the asymmetric Reformatsky reaction on aldehydic substrates. The influence both of the substrate and of the ligand on the stereochemical pathway has been investigated by varying the structure of the carbonyl substrate and of the optically active aminodiols. © 1995 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Polymerisation von optisch aktiven α-Olefinen, wie (R)-4-Phenyl-1-hexen (1) und (S)-5-Phenyl-1-hepten (2), mit ZIEGLER-NATTA-Katalysatoren wie TiCl3/(„ARA“) oder VCl4/Al[CH2CH(CH3)2] wird untersucht. 2 liefert Polymere, die bei Raumtemperatur amorph sind; kein Beweis sterischer Ordnung wird durch IR-Untersuchung erhalten, aber 1H-NMR-Spektren zeigen die Anwesenheit einer partiellen Stereoregularität an. Im Gegensatz dazu liefert 1 Polymere, die in siedenden Lösungsmitteln vorwiegend unlöslich sind und die nach den Röntgendiagrammen kristallin sind, was auf das Vorhandensein von isotaktischen Strukturen hinweist. Durch die Copolymerisation von 1 mit 4-Methyl-1-penten werden kristalline Polymere erhalten, die wahrscheinlich statistische coisotaktische Struktur besitzen, wie mit Hilfe der Röntgendiagramme der IR-Spektren und des Drehungsvermögens gezeigt wird.
    Notes: The polymerization of optically active phenyl-α-olefins, such as (R)-4-phenyl-1-hexene (1) and (S)-5-phenyl-1-heptene (2), has been performed by TiCl3/(“ARA”) or VCl4/Al[CH2CH(CH3)2]3 catalyst. 2 gives polymers which are amorphous at room temperature; no evidence of stereoregularity is obtained by IR investigation, whereas 1H-NMR spectra seem to give some indication of steric order. By contrast, the polymers from 1, which are largely insoluble in boiling solvents, are crystalline at X-ray examination according to an isotactic structure. The copolymerization of 1 with 4-methyl-1-pentene (3) gives statistical copolymers which appear to be coisotactic. This is confirmed by crystallinity at X-ray examination, IR and optical activity data.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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