Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Side-chain modifications  (1)
  • regio-selectivity  (1)
  • 1
    ISSN: 0947-6539
    Keywords: clusters ; fullerenes ; nitrenes ; regio-selectivity ; valence isomerization ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis, isolation, and spectroscopic characterization of the bisimino[60]fullerenes C60(NCOOR)2 (1a: R = Et, 1b. R = tBu) with a cis-1 addition pattern as well as of their regioisomeric analogues 2-7 with different addition patterns are described. Whereas compounds 2-7 are typical fulleroaziridines and obey the rule of the minimization of [5,6] double bonds, the cis-1 isomers 1a and 1b represent the first examples of fullerene derivatives with open transannular [6,6] bonds. Characteristic features within the fullerene framework of these valence isomers VI are the presence of a doubly bridged open 14-membered ring with a phenanthrene perimeter as well as of an 8-membered 1,4-diazocine heterocycle. Moreover, it is shown that, by transforming cis-1-C60(NCOOtBu)2 (1b) into cis-1-C60(NH)2 (1c), the fullerene cage can be closed in an intraring 2π→2s̰ isomerization to valence isomer V. These are the first chemical modifications of the fullerene core that allow the synthesis of both open and closed valence isomers with the same addition pattern. Density-functional as well as AM1 calculations corroborate the experimental findings that it depends on the addition pattern as well as on the nature of the addends whether or not the transannular [6,6] bonds are closed. Only in the cis-1 adducts C60(NR)2 that prefer planar imino bridges (e.g., carbamates or amides) are the open forms VI more stable than the closed isomers V.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0947-3440
    Keywords: Fullerenes ; Active ester ; Coupling reactions ; Side-chain modifications ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Side-chain modifications of fullerenes can be achieved starting from the malonic acid 2, which is easily accessible by saponification of the corresponding diethyl malonate adduct 1 and is therefore an ideal building block for side chain chemistry on fullerenes. Coupling reactions are carried out via the synthesis of the fullerene active ester 4, which is formed by the reaction of the malonic acid 2 with N-hydroxysuccinimide. During this reaction the malonic acid undergoes decarboxylation, yielding an acetic acid derivative instead of a malonic system. The active ester 4 is isolable and represents an ideal building block for fullerene chemistry. Sidechain modifications can also be carried out as one-step reactions by preparing 4 in situ. We have performed coupling reactions with various compounds containing primary or secondary amino groups.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...