Unprecedented alkene stereocontrol in the Claisen rearrangement of cyclic bis-allylic esters. 
The Ireland and ester enolate Claisen rearrangements of tertiary substituted bis-allylic esters derived from cyclohexenones afford pentenoic acids that possess tri- and tetrasubstituted alkylidenes with unprecedented levels of stereoselectivity.  In some cases the higher energy exocyclic alkene is the major product. [ reaction: see text]