Stereoselective Access to Fully Substituted Aldehyde-Derived Silyl Enol Ethers by Iridium-Catalyzed Alkene Isomerization.

An in situ generated cationic Ir-catalyst isomerizes simple allylic silyl ethers into valuable, fully substituted aldehyde-derived silyl enol ethers. Importantly, by judicious choice of substrate, either of the two possible stereoisomers of a given enolate derivative is accessible with complete stereoselectivity. One-pot isomerization-aldol and isomerization-allylation processes illustrate the synthetic utility of this method.