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  • 1
    ISSN: 1434-4475
    Keywords: Aminobicyclo[n. 1.0]alkane derivatives ; 2-Cyclopropylidene-1,3-cycloalkanedione intermediates ; Cyclopropanes, nucleophilic substitution at
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Reaction of morpholinobicycloalkyl-dimedone4 C with various CH-acids3 leads to a substitution of theexo-dimedone unit as a consequence of a strong preference of theexo-leaving group in a bicyclic compound of type4 and5, respectively. Dimedone (3 C) as a nucleophile, however, makes theexo substitution unproductive in4 C and allows the displacement of the morpholino moiety leading to12 C. Thus compounds12 C–12 F could be obtained directly from the N,O-acetal1 and the CH-acids3 C–3 F by a twofold substitution, the isolation of the monoalkylated compounds4 not being necessary. Formation of12 C–12 F involves aMichael addition of3 C–3 F to the unstable 2-Cyclopropylidene-1,3-cycloalkanedione intermediates7 C–7 F. Cyclopentanedione3 F as a CH-acid and1 gave the enamine17 F besides12 F. The Hexahydroazepino-N,O-acetal19 in this special case was superior leading exclusively to12 F.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-4475
    Keywords: Aminocyclopropane derivatives ; Diacyclomethylenecyclopropane intermediates ; Cyclopropanes, nucleophilic substitution at
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Reaction of HexahydroazepinobicycloalkylMeldrum's acid7 Ba-7 Bd or PiperidinocyclopropylMeldrum's acid7 Ce withMeldrum's acid (1) generates cyclopropanes possessing two isopropylidene malonate moieties. In the solid state the bicyclic derivatives were found to be dienolic compounds11 a-11 d, whereas the monocyclic system has the tetracarbonyl structure10e. 7a-7d, the starting materials for the synthesis of11 a-11 d, were obtained from1 and O,N-acetal4B or aminal6B.
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  • 3
    ISSN: 1434-4475
    Keywords: Aminocyclopropane derivatives ; Diacylmethylenecyclopropane intermediates ; Cyclopropanes, nucleophilic substitution at
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Piperidinocyclopropyl-dimedone (9 a),Meldrum's acid (9 b), and barbituric acid (9 c) were synthesized by aminoalkylation of CH-acids8 a–8 c with silyl-N,O-acetal7. In9 a–9 c the piperidino moiety was displaced by interaction with weakly basic carbanions derived from CH-acids8 a–8 g leading to compounds11,14,15, and16. A scrambling of the CH-acid being present in9 and the CH-acid8 added as a nucleophile generally did not take place. This allowed the specific preparation of cyclopropanes possessing two different CH-acidic substituents at the C1 atom. In one special case an exchange reaction of the CH-acidic moieties was observed to a minor extent. The nucleophilic substitution at the dimedone compound9 a was more or less strongly limited by a ring opening reaction.
    Type of Medium: Electronic Resource
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