Although tetrahydropyran is an obscure compound, tetrahydropyranyl ethers are of broad utility in [[organic synthesis]]. Specifically, the 2-tetrahydropyranyl (THP) group is a common [[protecting group]] for [[alcohol]]s.<ref>{{OrgSynth | title = Methyl 4-Hydroxy-2-butynoate | first1 = R. A. | last1 = Earl | first2 = L. B. | last2 = Townsend | collvol = 7 | collvolpages = 334 | year = 1981 | volume = 60 | page = 81 | doi = 10.15227/orgsyn.060.0081 | prep = cv7p0334}}</ref><ref>{{OrgSynth | title =<nowiki>Diethyl [(2-Tetrahydropyranyloxy)methyl]phosphonate</nowiki> | first = Arthur F. | last = Kluge | collvol = 7 | collvolpages = 160 | year = 1986 | volume = 64 | page = 80 | doi = 10.15227/orgsyn.064.0080 | prep = cv7p0160}}</ref> Alcohols react with with [[3,4-Dihydropyran|3,4-dihydropyran]] to give 2-tetrahydropyranyl ethers. These ethers are resilient to a variety of reactions. The alcohol can later be restored by acid-catalyzed [[hydrolysis]]. This hydrolysis reforms the parent alcohol as well as 5-hydroxypentanal.<ref name = Greene />
Although tetrahydropyran is an obscure compound, tetrahydropyranyl ethers are of broad utility in [[organic synthesis]]. Specifically, the 2-tetrahydropyranyl (THP) group is a common [[protecting group]] for [[alcohol]]s.<ref>{{OrgSynth | title = Methyl 4-Hydroxy-2-butynoate | first1 = R. A. | last1 = Earl | first2 = L. B. | last2 = Townsend | collvol = 7 | collvolpages = 334 | year = 1981 | volume = 60 | page = 81 | doi = 10.15227/orgsyn.060.0081 | prep = cv7p0334}}</ref><ref>{{OrgSynth | title =<nowiki>Diethyl [(2-Tetrahydropyranyloxy)methyl]phosphonate</nowiki> | first = Arthur F. | last = Kluge | collvol = 7 | collvolpages = 160 | year = 1986 | volume = 64 | page = 80 | doi = 10.15227/orgsyn.064.0080 | prep = cv7p0160}}</ref> Alcohols react with with [[3,4-Dihydropyran|3,4-dihydropyran]] to give 2-tetrahydropyranyl ethers. These ethers are resilient to a variety of reactions. The alcohol can later be restored by acid-catalyzed [[hydrolysis]]. This hydrolysis reforms the parent alcohol as well as 5-hydroxypentanal.<ref name = Greene />
:[[File:THPmeth.png|thumb|center|320 px|Protection of alcohol as THP ether followed by deprotection.]]]]
In a typical procedure, the alcohol is treated with [[3,4-Dihydropyran|3,4-dihydropyran]] and [[P-Toluenesulfonic acid|''p''-toluenesulfonic acid]] in [[dichloromethane]] at ambient temperature.<ref name = Greene>{{cite book|title = Greene's Protective Groups in Organic Synthesis|chapter = Protection for the Hydroxyl Group, Including 1,2‐ and 1,3‐Diols|pages = 16-366|edition = 4th|last1 = Wuts|first1 = Peter G. M.|last2 = Greene|first2 = Theodora W.|doi = 10.1002/9780470053485.ch2|year = 2006|isbn = 9780470053485}}</ref>
In a typical procedure, the alcohol is treated with [[3,4-Dihydropyran|3,4-dihydropyran]] and [[P-Toluenesulfonic acid|''p''-toluenesulfonic acid]] in [[dichloromethane]] at ambient temperature.<ref name = Greene>{{cite book|title = Greene's Protective Groups in Organic Synthesis|chapter = Protection for the Hydroxyl Group, Including 1,2‐ and 1,3‐Diols|pages = 16-366|edition = 4th|last1 = Wuts|first1 = Peter G. M.|last2 = Greene|first2 = Theodora W.|doi = 10.1002/9780470053485.ch2|year = 2006|isbn = 9780470053485}}</ref>
[[File:THPProtection.png|none|thumb|610x610px|THP protection used in the [[total synthesis]] of solandelactone E<ref>{{Cite journal|last1=Robinson|first1=Anna|last2=Aggarwal|first2=Varinder K.|date=2010|title=Asymmetric Total Synthesis of Solandelactone E: Stereocontrolled Synthesis of the 2-ene-1,4-diol Core through a Lithiation–Borylation–Allylation Sequence|journal=[[Angewandte Chemie International Edition]]|volume=49|issue=37|pages=6673–6675|doi=10.1002/anie.201003236}}</ref>]]
[[File:THPProtection.png|center|thumb|610x610px|THP protection used in the [[total synthesis]] of solandelactone E<ref>{{Cite journal|last1=Robinson|first1=Anna|last2=Aggarwal|first2=Varinder K.|date=2010|title=Asymmetric Total Synthesis of Solandelactone E: Stereocontrolled Synthesis of the 2-ene-1,4-diol Core through a Lithiation–Borylation–Allylation Sequence|journal=[[Angewandte Chemie International Edition]]|volume=49|issue=37|pages=6673–6675|doi=10.1002/anie.201003236}}</ref>]]
Alternatively the THP ether is generated under the conditions akin to those for the [[Mitsunobu reaction]]. Thus the alcohol is treated with 2-hydroxytetrahydropyranyl, [[triphenylphosphine]], [[diethyl azodicarboxylate]] (DEAD) in [[tetrahydrofuran]] (THF).
Alternatively the THP ether is generated under the conditions akin to those for the [[Mitsunobu reaction]]. Thus the alcohol is treated with 2-hydroxytetrahydropyranyl, [[triphenylphosphine]], [[diethyl azodicarboxylate]] (DEAD) in [[tetrahydrofuran]] (THF).
Revision as of 15:07, 17 January 2019
This article is about tetrahydropyran, whose IUPAC name is oxane. For ethylene oxide, which has occasionally been named as oxane, see oxirane.
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. Derivatives of tetrahydropyran are, however, more common. 2-Tetrahydropyranyl (THP-) ethers derived from the reaction of alcohols and 3,4-dihydropyran are commonly used as protecting groups in organic synthesis.[2] Furthermore, a tetrahydropyran ring system, i.e., five carbon atoms and an oxygen, is the core of pyranose sugars, such as glucose.
Structure and preparation
In gas phase, the THP exists in its lowest energy Cs symmetry chair conformation.[3]
Although tetrahydropyran is an obscure compound, tetrahydropyranyl ethers are of broad utility in organic synthesis. Specifically, the 2-tetrahydropyranyl (THP) group is a common protecting group for alcohols.[5][6] Alcohols react with with 3,4-dihydropyran to give 2-tetrahydropyranyl ethers. These ethers are resilient to a variety of reactions. The alcohol can later be restored by acid-catalyzed hydrolysis. This hydrolysis reforms the parent alcohol as well as 5-hydroxypentanal.[2]
Protection of alcohol as THP ether followed by deprotection.]]
^ abcWuts, Peter G. M.; Greene, Theodora W. (2006). "Protection for the Hydroxyl Group, Including 1,2‐ and 1,3‐Diols". Greene's Protective Groups in Organic Synthesis (4th ed.). pp. 16–366. doi:10.1002/9780470053485.ch2. ISBN 9780470053485.
^Robinson, Anna; Aggarwal, Varinder K. (2010). "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. doi:10.1002/anie.201003236.
