5- and 6-exocyclic products, cis-2,3,5-trisubstituted tetrahydrofurans, and cis-2,3,6-trisubstituted tetrahydropyrans via prins-type cyclization

A novel Prins-type cyclization method and the stereochemistry of terminally substituted alkynyl alcohols for the synthesis of 6-exocyclization to yield cis-2,3,6-trisubstituted tetrahydropyrans is described. The newly developed method opens pathways to design functionalized heterocyclic frameworks.