Model studies of the overall 5-endo-trig iodocyclization of homoallylic alcohols

Overall 5-endo-trig iodocyclizations of homoallylic alcohols, with a range of substitution patterns, leading to beta-iodotetrahydrofurans are usually highly efficient and stereoselective when carried out in anhydrous acetonit rile in the presence of sodium hydrogen carbonate. Such cyclizations, which are not exceptions to Baldwin's rules as they are electrophile-driven, app ear to proceed via a well-ordered chair-like transition state. The iodine c an be replaced by hydroxy, acetoxy and azide groups.