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  • Electronic Resource  (3)
  • Organic Chemistry  (2)
  • reactivity  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 362-376 
    ISSN: 0894-3230
    Keywords: highly strained cyclophanes ; reactivity ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An essential feature of the concept of aromaticity has been the stability and lack of reactivity of aromatics relative to that of other unsaturated compounds. Contrary to this general experience, high and unusual reactivity is encountered when simple, monocyclic benzene rings are bent by short bridges into a boat-shaped conformation, as is the case in small [n] paracyclophanes (n ≤ 8) and [n]metacyclophanes (n ≤ 7). This is illustrated, mostly with examples taken from the authors' own work, for thermal and photochemical behavior and reactions with electrophiles, nucleophiles and dienophiles. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The difference in reactivity of small [n]cyclophanes towards CF3CO2H is discussed in terms of charge densities, strain energies and proton affinities. These data are calculated with MNDO and MINDO/3 for para-, meta- and ortho-cyclophanes and for their ipso-protonation products; an attempt is made to transform gas phase ΔHf0 values into liquid phase ΔH0f values. Experimental evidence is presented that the acid catalyzed rearrangement of [5]paracyclophane to its ortho-isomer proceeds via two consecutive 1,2-carbon shifts without deprotonation; intermediate adducts were identified by NMR-spectroscopy. Thus, a gradual shift in reaction pattern in the series [4]-, [5]- and [6]paracyclophane is observed experimentally, in line with the calculational results.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 3 (1990), S. 295-300 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The molecular structure of [4]paracyclophane was optimized at the semiempirical MNDO and the ab initio STO-3G level. A comparison of the results showed that the benzene ring is much less bent at the STO-3G level. Although some bond alternation is predicted at both levels of theory, the aromatic carbon-carbon bond lengths are still in the range typical of highly delocalized compounds. The calculated strain energy [SE(tot.)] of [4]paracyclophane is larger for the STO-3G structure. Nevertheless, the distributions of SE(tot.) over the bent benzene ring [SE(bb.)] and the oligomethylene bridge [SE(br.)] are the same for the MNDO and STO-3G structures.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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