Tetrahydropyran is an organic compound consisting of a saturated six-membered ring containing five carbon atoms and one oxygen atom. Tetrahydropyrans are common structural motifs in natural products and synthetic therapeutic molecules. In nature, these six-membered oxygen heterocycles are usually assembled by intramolecular reactions, including oxygen Michael addition or ring opening of epoxy alcohols. In fact, polyether natural products have been particularly extensively studied for their fascinating structures and important biological properties; these are often formed through endoselective epoxy open cascades.
Pyrans are an important class of six-membered heterocyclic compounds, non-aromatic rings, composed of five carbon atoms and one oxygen atom, and contain two double bonds. The molecular formula of pyran is C5H6O, and there are two isomers. Pyrans, together with benzo derivatives, form scaffolds for a variety of drug applications, many of which are approved and promising candidates in clinical trials and recently isolated bioactive natural products.