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.