The preparation of the perisubstituted naphthalene derivatives 1-8 is described for the first time, and possible axial or axial and planar chirality of these compounds is investigated by means of dynamic 1H NMR spectroscopy. Molecular chirality, caused by hindered rotation, can be proven for compounds 1 and 3 at room temperature and for 2 at 193 K by the observation of magnetic inequivalence of isochronous protons in a diastereotopic environment. Temperature-dependent 1H NMR spectra indicate that for 2 the coalescence temperature lies between 193 K and 213 K, and above 320 K for 3. By assuming Tcoal- = 200 K for 2 and Tcoal. > 320 K for 3 the following ⊿G≠-values were estimated with the aid of known approximations from the 1H NMR spectral parameters Δν = νA-νB and JAB for the methylene and methyl groups of the oxazoline system present in these species: ⊿G≠ (2) = 10.1 kcal/mole (at 200 K), ⊿G≠ (3) = 17.3 (16.2) kcal/mole (at 320 K). These ⊿G≠-values represent the energy barriers of a dynamic intramolecular process, presumably according to a more or less hindered rotation in the purely axially chiral molecules 2 and 3. With the aid of these ⊿G≠-values and model considerations a description of the energy profile diagram of the hindered rotation in compounds 2 and 8 is attempted.
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