The High Stereoselectivity of the Tandem Sequence Diels-Alder Reaction/Ireland­-Claisen Rearrangement Starting from Substituted O-(<i>E</i>)-Buta-1,3-dienyl Ketene Acetals and Cyclic Dienophiles

A new tandem reaction leads to bicyclic cyclohexene derivatives with complete control of the relative configuration of the four chiral centers formed. The high diastereoselectivity is the consequence of an endo-selective Diels-Alder reaction followed by an Ireland-Claisen rearrangement that proceeds via a boat-like transition state.