Oxygen to carbon rearrangements of anomerically linked alkenols from tetrahydropyran derivatives: an investigation of the reaction mechanism via a double isotopic labelling crossover study

A variety of alkenol tetrahydropyran derivatives were prepared and subjected to a tin tetrachloride promoted anomeric oxygen to carbon rearrangement. Using this methodology many of the corresponding carbon-linked structures were synthesised, including alkenes and bicyclic ethers, in good yields. On the basis of an isotopic labelling study using H-2 incorporated into the side chain and ring system it is proposed that these reactions proceed via an intermolecular pathway.