Electrophilic Cyclization of Phenylalkynediols to Naphthyl(aryl)iodonium Triflates with Chelating Hydroxyls: Preparation and X-ray Analyses.

Alkynediols containing one propargylic alcohol as well as a second alcohol, which is propargylic or homopropargylic, react with PhI+CN-OTf (Stang's reagent) or 3,5-(CF3)2C6H3I+CN-OTf to afford naphthyl(aryl)iodonium triflates. The reaction occurs at room temperature over the course of 6-12 h and provides 36-82% yields of microcrystalline solids. Slow diffusion of Et2O into CH3CN solutions of the salts afforded X-ray quality crystals of five compounds with hydroxyl groups forming five- and six-membered chelation complexes with the iodine atom. Crystallizations from larger scale reactions (≥∼0.25 mmol) were generally facile from CH2Cl2.