Reactivities of Stable Rotamers. XVIII. Reactions of 9-[2-(1-Hydroxyethyl)-1-naphthyl]fluorene Rotamers with Sulfuric Acid and Thionyl Chloride

Treatment of the title compound with 70% sulfuric acid in 1,2-dimethoxyethane caused cyclization for the ap isomer, whereas it did dehydration to produce a vinyl compound smoothly for the sp. The same treatment with 10% sulfuric acid in 1,2-dimethoxyethane afforded the corresponding vinyl compounds from both rotamers. Treatment of the alcohol with thionyl chloride afforded the corresponding chloride in the case of the sp-alcohol, while it gave the sp-vinyl compound in addition to the ap-chloride in the case of the ap-alcohol. The change in solvents in the reaction of the ap form caused the change in the ratio of the olefin vs. the chloride: The polar solvents enhance the rates of formation of the chloride. Introduction of three deuteriums to the methyl group of the ap-form of the title compound suppressed the formation of the olefin to some extent. The results are explained on the grounds of steric effects in the ion-pair formation from the chlorosulfites and the contribution of the C–H stretching in the ...