Preparation of oxepanes, oxepenes, and oxocanes by iodoetherification using bis(sym-collidine)iodine(I) hexafluorophosphate as electrophile

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. Oxocanes could be obtained in moderate yields (18-27%).