Reactivities of Stable Rotamers. XLI. Reactions of 1-(9-Fluorenyl)-2-(1-methylethenyl)naphthalene Rotamers with Chalcogenyl Halides and Observation of Coloration During the Reaction of Methanesulfenyl Chloride and the ap-Rotamer

Abstract

Abstract Reactions of p-toluenesulfenyl chloride with the title olefins in carbon tetrachloride afforded an addition product and sp-1-(9-fluorenyl)-2-[1-(p-tolylthiomethyl)ethenyl]naphthalene in the case of ap, whereas the only product was ap-1-(9-fluorenyl)-2-[1-(p-tolylthiomethyl)ethenyl]naphthalene in the case of sp. No cyclized compounds, which are commonly observed in the reactions of the sp-isomer with halogens or halogen chloride, were detected. Various unsuccessful attempts, including use of methanesulfenyl chloride to take advantage of different sulfur acidity, use of a soft anion to retard deprotonation or a polar solvent to accelerate cyclization by stabilizing the intervening cations, have been made to find conditions for formation of the cyclized compound. Similar unsuccessful results were obtained with benzeneselenenyl halides. Such results are attributed to the effective participation of a chalcogen atom in stabilizing a β-carbocation, which opens momentarily but is less vulnerable to the SN2 type attack of the existing nucleophile. Coloration was observed in the reaction of the sp form with methanesulfenyl chloride.