Reagent-controlled stereoselective iodolactonizations.

[reaction: see text] Iodocyclizations are important transformations and among stereocontrolled iodocyclizations mostly substrate-controlled versions using a chiral auxiliary have been successfully investigated. This work reports on stereoselective reagent-controlled iodolactonizations applying a new method using a combination of ICl and a primary amine leading to the highest selectivities known so far.