Tetrahydropyran

Tetrahydropyran

Names
IUPAC name Oxane
Other names Tetrahydropyran, Oxacyclohexane
Identifiers
CAS Number	142-68-7 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:46941 Y
ChemSpider	8554 Y
DrugBank	DB02412 Y
ECHA InfoCard	100.005.048
KEGG	C15345 Y
PubChem CID	8894
UNII	V06I3ILG6B Y
InChI InChI=1S/C5H10O/c1-2-4-6-5-3-1/h1-5H2 Y Key: DHXVGJBLRPWPCS-UHFFFAOYSA-N Y InChI=1/C5H10O/c1-2-4-6-5-3-1/h1-5H2 Key: DHXVGJBLRPWPCS-UHFFFAOYAV
SMILES O1CCCCC1
Properties
Chemical formula	C5H10O
Molar mass	86.13 g/mol
Density	0.880 g/cm3
Melting point	−45 °C (−49 °F; 228 K)
Boiling point	88 °C (190 °F; 361 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Tetrahydropyran (THP) is the organic compound consisting of a saturated six-membered ring containing five carbon atoms and one oxygen atom. It is named by reference to pyran, which contains two double bonds, and may be produced from it by adding four hydrogens. In 2013, its preferred IUPAC name was established as oxane.^[1] The compound is a colourless volatile liquid, but is obscure. Derivatives of tetrahydropyran are, however, more common. Tetrahydropyranyl (THP-) ethers derived from the reaction of alcohols and dihydropyran are common intermediates in organic synthesis. Furthermore, a tetrahydropyran ring system, i.e., five carbon atoms and an oxygen, is the core of pyranose sugars, such as glucose. In gas phase, the THP exists in its lowest energy Cs symmetry chair conformation.^[2]

Preparation

One classic procedure for the organic synthesis of tetrahydropyran is by hydrogenation of dihydropyran with Raney nickel.^[3]

Reactions

In organic synthesis, the 2-tetrahydropyranyl group is used as a protecting group for alcohols.^[4][5] Reaction of the alcohol with dihydropyran forms a tetrahydropyranyl ether, protecting the alcohol from a variety of reactions. The alcohol can later be restored readily by acidic hydrolysis with formation of 5-hydroxypentanal.

Alcohol protection

In organic synthesis, 2-tetrahydropyranyl group (THP) is used as a protecting group for alcohols.

Most common protection methods

• Treatment of alcohol with dihydropyran and p-toluenesulfonic acid in dichloromethane at ambient temperature^[6]

^[7]

• 2-hydroxytetrahydropyranyl, triphenylphosphine, diethyl azodicarboxylate (DEAD) in THF

Most common deprotection methods

• Acetic acid (AcOH) in THF/water solution or p-toluenesulfonic acid in water
• Pyridinium p-toluenesulfonate (PPTS) in ethanol

See also

• Tetrahydrofuran (THF)
• Pyran
• Dioxane and Trioxane, which have two and three oxygen atoms as part of their six-membered rings respectively

References

1. ↑ "New IUPAC Organic Nomenclature - Chemical Information BULLETIN" (PDF). 
2. ↑ Builth-Williams, J. D.; Bellm, S. M.; Chiari, L.; Thorn, P. A.; Jones, D. B.; Chaluvadi, H.; Madison, D. H.; Ning, C. G.; Lohmann, B. (2013-07-21). "A dynamical (e,2e) investigation of the structurally related cyclic ethers tetrahydrofuran, tetrahydropyran, and 1,4-dioxane". The Journal of Chemical Physics. 139 (3): 034306. ISSN 0021-9606. doi:10.1063/1.4813237. 
3. ↑ D. W. Andrus; John R. Johnson (1955). "Tetrahydropyran". Org. Synth. ; Coll. Vol., 3, p. 794 
4. ↑ R. A. Earl L. B. Townsend (1990). "Methyl 4-Hydroxy-2-butynoate". Org. Synth. ; Coll. Vol., 7, p. 334 
5. ↑ Arthur F. Kluge (1990). "Diethyl [(2-Tetrahydropyranyloxy)methyl]phosphonate". Org. Synth. ; Coll. Vol., 7, p. 160 
6. ↑ Wuts, Peter G. M.; Greene, Theodora W. Greene's Protective Groups in Organic Synthesis, Fourth Edition - Wuts - Wiley Online Library. doi:10.1002/0470053488. 
7. ↑ Robinson, Anna; Aggarwal, Varinder K. (2010-09-03). "Asymmetric Total Synthesis of Solandelactone E: Stereocontrolled Synthesis of the 2-ene-1,4-diol Core through a Lithiation–Borylation–Allylation Sequence". Angewandte Chemie International Edition. 49 (37): 6673–6675. ISSN 1521-3773. doi:10.1002/anie.201003236.