T. Kamada, O. Yamamoto
Oct 1, 1979
Citations
0
Influential Citations
4
Citations
Journal
Bulletin of the Chemical Society of Japan
Abstract
The conformations of 8-methyl (4) and 8-ethyl-8,9,10,11-tetrahydro-7H-cycloocta[de]naphthalenes (5) have been studied on the basis of the NMR spectra. It was found that both compounds exist as an equilibrium mixture of the axial-boat (ab) and the equatorial-boat (eb) conformers in solution. The 1H spectra revealed that the boat conformations of all these isomers are somewhat in the distorted form due to the steric repulsion between the interior benzyl protons. The free-energy differences (−ΔG°) between the two isomers (ab\ightleftarrowseb) in 4 and 5 were calculated from the 13C spectra and found to be 0.09 and −0.07 kcal/mol, respectively. These results are discussed in terms of the structural and conformational features of the 8-membered pericyclized naphthalene ring and compared with the cyclohexane ring.