Sequencing pericyclic reactions: The ester dienolate [2,3]-Wittig/oxy-Coperearrangement/carbonyl ene reaction, a new access to substituted carbocycles

The sequential ester dienolate [2,3]-Wittig/oxy-Cope rearrangement/carbonyl ene reaction has been investigated. Acyclic alpha,beta -unsaturated alpha -allyloxy-substitutcd esters 1a-j were transformed into cyclopentane- or cy clohexanecarboxylates 6a-i and 7a-7d. This study presents a domino ester di enolate [2,3]-Wittig/oxy-Cope rearrangement or a domino oxy-Cope rearrangem ent/carbonyl ene reaction, depending on the substrate structure. The therma l intramolecular type-I carbonyl ene reaction as the terminating ring-closi ng reaction proceeds with high simple diastereoselectivity, but low induced diastereoselectivity. The corresponding type-II ene reaction afforded the cyclohexanecarboxylates 7a-d in high yield with complete simple and induced diastereoselectivity. Unfortunately, an attempted auxiliary-controlled ena ntioselective sequence was inefficient.