2,3-二氢吡喃，分子式 C₅H₈O。

无色易燃液体，有类似醚的气味。溶于水和乙醇、乙醚等有机溶剂。

在少量酸催化下，与醇、酚类起加成反应，生成稳定的α-四氢吡喃醚类化合物。

该加成物是羟基的保护基，对氧化剂、碱、烃基锂、格氏试剂、催化加氢均较稳定，但遇无机酸会缓慢水解，生成原来的醇和5-羟基戊醛。

Dihydropyran is a heterocyclic compound with the formula C₅H₈O. The six-membered, not aromatic, ring has five carbon atoms and one oxygen atom. It contains one double bond. There are two isomers of dihydropyran that differ by the location of the double bond. 3,4-Dihydro-2H-pyran has a double bond at position 5; 3,6-dihydro-2H-pyran has the double bond at position 4.