Highly cis- or trans-selective oxygen to carbon rearrangements of anomerically linked 6-substituted tetrahydropyranly enol ethers

摘要

Low temperature Lewis acid catalysed oxygen to carbon rearrangements of anomerically linked 6-substituted tetrahydropyranyl enol ethers lead to the corresponding trans-ketones in a highly diastereoselective manner, whereas at higher temperatures the cis-ketones are formed with a high degree of selectivity under thermodynamic control.