<unk>  is the organic compound with the formula C5H8O.  This cyclic ether is used to protect alcohols in organic synthesis.<unk>  is prepared by the dehydration of tetrahydrofurfuryl alcohol over alumina at<unk> 00-400 °C.<unk>  reacts with alcohols to form tetrahydropyranyl ethers.  These ethers resist a variety of reactions, and the THP group can be removed with aqueous acid.
2,3-Dihydropyran
Tetrahydropyran
Aristolochic acid
Cyanic acid
Triethanolamine
Cholesteryl ester
Tetrahydrozoline
Dimethylethanolamine