Oxepanes have been obtained in good yields (40-95%) by iodoetherification of unsaturated alcohols using bis (sym-collidine) iodine (I) hexafluorophosphate (1) as electrophile, either by 7-exo-mode or 7-endo-mode cyclizations. 4-Oxepenes could also be formed from 4, 6- heptadien-1-ols; the presence of a substituent on the carbon 6 appeared necessary, while for steric reasons the presence of a substituent on the carbon 7 was unfavorable. ...
