Highly Efficient Transfer of Chirality from Macrocyclic Conformation in the Tandem Oxy-Cope/Claisen/Ene Reaction

We report three highly stereoselective pericyclic reactions occurring in cascade leading to the
synthesis of Decalins skeletons possessing two contiguous quaternary centers. The tandem reaction is
triggered by an oxy-Cope rearrangement to create in situ a 10-membered ring enol ether macrocyle 6,
which immediately rearranges via a Claisen [3,3] shift to the corresponding E-cyclodec-6-en-1-one 7. The
latter spontaneously cyclizes via a transannular ene reaction to produce Decalin 5. Analysis of the
mechanism with respect to the origin of the high diastereoselectivity of the tandem oxy-Cope/Claisen/ene
reaction is presented.