Regarding the structure of [2.2](2,6,2',7')-naphthalenophane-1,11-diene and its conformational mobility |
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Authors: | Magdy N Iskander James A Reiss |
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Institution: | Department of Organic Chemistry, La Trobe University, Bundoora, Victoria 3083, Australia |
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Abstract: | The synthesis of 2.2](2,6,2',7')naphthalenophane -1,11 - diene 4 has been effected by pyrolysis of the bis-sulphoxide 10, in turn prepared by a ring-contraction procedure of the 3.3]dithiacyclophane 7. The diene 4 has been fully characterized by spectroscopic and chemical methods. The variable-temperature 1H NMR spectra of the diene 4 indicated that the compound undergoes conformational flipping in solution and has a conformational energy barrier ΔG≠25°. 14.9 kcal mol-1 and a coalescence temperature Tc 38° for the internal protons Hc and Hc' (at 100 MHz). These results differ from those previously recorded. A complete assignment of the pmr spectrum of the cyclophane diene 4 at 270 MHz is presented together with the spectrum of the corresponding saturated 2.2]cyclophane 3. |
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