Restricted Rotation Involving the Tetrahedral Carbon. XXXIV. Stable Rotamers of 9-Arylfluorenes Carrying Oxygen-substituents in the Ortho Position of the Aryl Group

Article abstract of DOI:10.1246/bcsj.53.3248

9-(2-Hydroxy-1-naphthyl)fluorene, 9-(2-hydroxy-4,6-dimethylphenyl)fluorene, and their methyl ethers have been prepared.They give stable rotamers, sp and ap, at room temperature. ap forms of the hydroxylic compounds are favored over the sp and contrary is true for the methyl ethers.These results are attributed to the stabilization of the ap form of the hydroxylic compounds due to intramolecular OH...? interaction.Barriers to rotation are ca. 105 kJ mol^-1.