3,4-Dihydro-2H-pyran is widely used in organic synthesis as a versatile intermediate. It is particularly valuable in the preparation of various heterocyclic compounds, which are essential in the development of pharmaceuticals and agrochemicals. The compound is often employed as a protecting group for alcohols, where it forms tetrahydropyranyl ethers, which are stable under a range of reaction conditions but can be easily removed when needed. Additionally, it serves as a key building block in the synthesis of natural products and complex organic molecules, including those with potential biological activity. Its reactivity in cycloaddition reactions also makes it useful in the construction of complex ring systems, which are common in many drugs and bioactive compounds.