- Paracyclophanes: Extending the bridges. Synthesis
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Preparatively satisfactory routes to [3.2]paracyclophane (10), [4.2]paracyclophane (14), [4.3]paracyclophane (19) as well as several derivatives of these compounds - among others the bromides 25, the ester 31, the diesters 40-43 - are described using well-established methods of cyclophane chemistry (ring-closure reactions leading to thiacyclophanes, ring contraction by sulfone pyrolysis). The parent systems and their derivatives are now available in gram quantities allowing a study of their chemical properties. Wiley-VCH Verlag GmbH & Co. KGaA, 2009.
- Pechlivanidis, Zissis,Hopf, Henning,Ernst, Ludger
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experimental part
p. 223 - 237
(2009/06/21)
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- Laser flash photolysis of [3,n]paracyclophan-2-ones. Direct observation and chemical behavior of 4,4′-(1,n-alkanediyl)bisbenzyl biradicals
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The 4,4′-(1,n-alkanediyl)bisbenzyl biradicals (2b-d) have been generated from the Norrish type-I reaction of [3,n]paracyclophan-2-ones (1b-d) giving the paracyclophanes 3b-d as the only reaction products. The behavior of biradicals 2b-d has been studied in detail and compared with the previously reported biradical 2a. The lifetimes increase as the chain length decreases and are affected by the solvent viscosity, thus showing the effect of the length of the chain on the conformations of the biradicals. Quenching with persistent radicals such as TEMPO resulted in length-dependent rate constants. Finally, the study of the magnetic field effects on the biradical lifetimes suggest that ISC control determines biradical lifetimes for long-chain systems.
- Font-Sanchis, Enrique,Miranda, Miguel A.,Perez-Prieto, Julia,Scaiano
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p. 6131 - 6135
(2007/10/03)
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