The Claisen rearrangement of the allyl vinyl ethers 9 and 19a has been used to explore the possibility that reactions proceeding by six-membered cyclic transition states may exhibit a selectivity for either axial or equatorial attack at a double bond exocylic to a cyclohexane ring. In the two cases studied there was a slight preference for attack to form a new equatorial bond, the product ratios being 52% equatorial and 48% axial for enol ether 9 ...
