3,4-Dihydro-2H-pyran

colorless to light yellow liqui

Widely used hydroxyl-protecting reagent3,4-Dihydro-2H-pyran is used as a hydroxyl-protecting reagent in organic synthesis. It acts as an intermediate in synthetic chemistry. It is used to protect various reactive functional groups. It is involved in the polymerization reaction either alone or with unsaturated compound and finds application in polymer industries. Further, it is employed in the preparation of bicyclic compounds of epoxide-fused, halo compounds and allenic alcohols.

3,4-Dihydro-2H-pyran can be used as a reactant to synthesize:

• Tetrahydropyranylated product from alcohols in the presence of phenolsulfonic acid-formaldehyde resin catalyst.
• Tetrahydropyran derivatives by reacting pyrazoles in the presence of trifluoroacetic acid.
• 1,2,3,4-Tetrahydroquinoline derivatives by cation-exchange resin catalyzed Domino reaction with aromatic amines.
• Tetrahydroquinolines from aryl azides in the presence of FeCl3-NaI.

Flammable

A flammable and very dangerous fire hazard when exposed to heat or flame; can react vigorously with oxidzing materials. Keep away from heat and open flame. To fight fire, use alcohol foam, CO2, or dry chemical. When heated to decomposition it emits acrid smoke and irritating

Partially dry dihydropyran with Na2CO3, then fractionally distil it. The fraction b 84-85o is refluxed with Na until hydrogen no longer evolves when fresh Na is added. It is then dried, and distilled again through a 60 x 1.2cm column packed with glass rings [Brandon et al. J Am Chem Soc 72 2120 1950, UV: Elington et al. J Chem Soc 2873 1952, NMR: Bushweller & O'Neil Tetrahedron Lett 4713 1969]. It has been characterised as the 3,5-dinitrobenzoyloxy-tetrahydrofuran derivative, m 103o which forms pale yellow crystals from dihydropyran/Et2O [Woods & Kramer J Am Chem Soc 69 2246 1947]. [Beilstein 17/1 V 181.]