Tetrahydrofuran is a heterocyclic organic compound with the molecular formula C4H8O. Tetrahydrofuran belongs to ethers and is the complete hydrogenation product of furan. It is a colorless, water-miscible organic liquid with small viscosity at normal temperature and pressure. Because of its long liquid range, it is a commonly used medium polar aprotic solvent. Its main use is as a precursor of high molecular polymers.
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.
Cyclanes are secondary metabolites that can be found in plants, and are also biochemicals that can be used in medicine. Cyclanes are found in pine trees, and are used in the making of plastics. Cyclenes are found in cinnamon, and have antifungal properties.