Modulating the stereochemical outcome of the Ireland-Claisen reaction of (E)- and (Z)-allylic glycolates

The diastereoselectivity of Ireland-Claisen rearrangements of allylic glycolates is dependent on the E:Z ratio of the silyl ketene acetals, the alkene geometry in the allyl unit, and the transition state topography. High yields and excellent diastereoselectivities (>95:5) have been achieved for selected substrates, including those with R2 = ethyl that results in a newly formed quaternary center. A discussion of the scope, selectivities, and transition state models will be presented.