Efficient method for tetrahydropyranylation of alcohols and phenols and deprotection of THP ethers using H14[NaP5W 30O110] as a Green Catalyst

Article abstract of DOI:10.1080/00397910600907274

A simple and effective method for tetrahydropyranylation of alcohols and phenols and the regeneration of THP ethers using a catalytic amount of H ₁₄[NaP₅W₃₀O₁₁₀] is reported. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/00397910600907274

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Efficient Method for Tetrahydropyranylation
of Alcohols and Phenols and Deprotection
of THP Ethers using H14[NaP5W30O110] as a
Green Catalyst
Majid M. Heravi a , Masoumeh Haghighi a , Fatemeh Derikvand a & Fatemeh
F. Bamoharram b
a Department of Chemistry, School of Science , Azzahra University , Vanak,
Tehran, Iran
b Department of Chemistry, School of Sciences , Azad University, Khorasan
Branch , Mashhad, Iran
Published online: 24 Nov 2006.
To cite this article: Majid M. Heravi , Masoumeh Haghighi , Fatemeh Derikvand & Fatemeh F. Bamoharram
(2006) Efficient Method for Tetrahydropyranylation of Alcohols and Phenols and Deprotection of THP Ethers
using H14[NaP5W30O110] as a Green Catalyst, Synthetic Communications: An International Journal for Rapid
Communication of Synthetic Organic Chemistry, 36:21, 3103-3107, DOI: 10.1080/00397910600907274
To link to this article: http://dx.doi.org/10.1080/00397910600907274
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Synthetic Communicationsw, 36: 3103–3107, 2006
Copyright # Taylor & Francis Group, LLC
ISSN 0039-7911 print/1532-2432 online
DOI: 10.1080/00397910600907274
Efficient Method for
Tetrahydropyranylation of Alcohols and
Phenols and Deprotection of THP Ethers
using H14[NaP5W30O110] as a
Green Catalyst
Majid M. Heravi, Masoumeh Haghighi, and
Fatemeh Derikvand
Department of Chemistry, School of Science, Azzahra University, Vanak,
Tehran, Iran
Fatemeh F. Bamoharram
Department of Chemistry, School of Sciences, Azad University,
Khorasan Branch, Mashhad, Iran
Abstract: A simple and effective method for tetrahydropyranylation of alcohols
and phenols and the regeneration of THP ethers using a catalytic amount of
H14[NaP5W30O110] is reported.
Keywords: Deprotection, depyranylation, heteropolyacids, protection, tetrahydro-
pyranylation
The protection and deprotection of alcohols and phenols is a common event in
multistep organic synthesis, and tetrahydropyranylation is one of the most fre-
quently employed methods.[1] The tetrahydropyranyl (THP) ethers are attrac-
tive because they are less expensive, easy to deprotect, and stable enough in
strong basic media, oxidative conditions, reduction with hydrides, reactions
involving Grignard reagents, lithium alkyls, and alkylating and acylating
reagents. Consequently, a variety of reagents have been developed for the
Received in Poland March 8, 2006
Address correspondence to Majid M. Heravi, Department of Chemistry, School of
Science, Azzahra University, Vanak, Tehran, Iran. E-mail: mmh1331@yahoo.com
3103

3104
M. M. Heravi et al.
tetrahydropyranylation of alcohols and phenols, which include mainly protic
acids,[2] Lewis acids,[3] solid acids,[4] solid-support reagents,[5] catalyst
immobilized in ionic liquids,[6] heteropolyoxometallats,[7] heteropolyacids,[8]
and many others.[9–11] The problems associated with the handling and
disposal of the inorganic acids, and their environmental and potential
hazards, have raised our interest in the development of alternative procedures
using solid acid catalysts.[12–17]
Because of their super acidic properties, heteropolyacids can be used in
reactions requiring electrophilic catalysis. They have a great capability for
practical use, because their redox and acidic properties can be controlled at
the atomic/molecular levels by changing the constituent. They are
promising solid acids and can replace environmentally harmful liquid acid
catalysts such as H2SO4.
To the best of our knowledge, there are no examples of the use of
preyssler-type heteropolyacids as catalyst for protection of alcohols and
phenols and deprotection of THP ethers. In continuation of our interest in
the catalytic activities of heteropolyacids,[18–21] we herein describe the use
of preyssler heteropolyacid as an effective catalyst for the tetrahydropyranyla-
tion of alcohols/deprotection of THP ethers (Scheme 1).
In the present method, alcohols, 3,4-dihydro-2H-pyran (DHP), and
catalytic amounts of H14[NaP5W30O110] are refluxed in CH2Cl2 to yield the
corresponding THP ethers. After completion of the reaction, the product is
purified by filtration and concentration of filtrate, followed by evaporation
of solvent and flash column chromatography on silica (hexane–toluene). A
wide variety of alcohols are converted to the corresponding THP ethers via
this procedure, and the results are shown in Table 1.
Note that phenols did not react in this condition, so in a competition
between a phenolic and alcoholic hydroxyl, alcohol protected but phenols
remained unchanged. Regioselective protection of hydroxyl group of
alcohols in the presence of the hydroxyl group of phenols is possible using
this method. However, surprisingly, the protection of phenols could be
achieved by using toluene as solvent in the presence of hetropolyacid
(Table 1).
The catalyst could be separated by simple filtration, washed with
diethylether, and reused in the same reaction. Results of the first experiment
and subsequent ones were the same in the course of the reaction of benzyl
alcohol and DHP.
The capability of H14[NaP5W30O110] to cleave the THP protective group
is also investigated to establish the regenerative potential of catalyst. To this
Scheme 1.

Tetrahydropyranylation of Alcohols and Phenols
3105
Table 1. Protection and deprotection of THP ethers using H14[NaP5W30O110
]
Protection
Deprotection
Entry
R
Time (h) Yield (%)a
Time (h)
Yield (%)a
1
2
PhCH22
2
90
90
92
94
93
92
90
94
75
75
2
99
98
97
99
98
98
97
97
98
99
2-Me-PhCH22
4-MeO-PhCH22
4-Br-PhCH22
4-NO2-PhCH22
Octyl-
1.5
1
2
3
2
4
2
2
5
2
2
6
2
2
7
Cyclohexyl-
2-Me-cyclohexyl-
Ph-b
4-Br-Ph-b
2.25
1
2
8
2
9
10
2
0.75
0.75
2
aYields are based on GC analysis.
bThe protection was carried out in refluxing toluene.
end, the THP ethers, heteropolyacid, and methanol are refluxed together,
affording the deprotected products. The results are summarized in Table 1.
In conclusion, this procedure provides a useful and clean alternative for
the preparation of THP ethers, as well as for their cleavage to the correspond-
ing alcohols. The main advantages of this methodology are the use of a hetero-
geneous, reusable, and environmentally benign catalyst, operational
simplicity, and high selectivity.
EXPERIMENTAL
Preparative Procedure for THP Ethers
A mixture of an alcohol or phenol (10 mmol), DHP (11 mmol), and
H14[NaP5W30O110] (0.1 mol%) were refluxed in dichloromethane or toluene
respectively. The progress of the reaction was monitored by thin-layer chrom-
atography (TLC) and gas chromatography (GC) (Table 1). After completion
of the reaction, the product was purified by filtering the reaction mixture, eva-
porating the solvent, and column chromatography on silica gel (hexane–
toluene). The products were identified by comparison of physical and spectro-
scopic data with those of authentic samples.
Deprotection of THP Ethers
THP ethers (10 mmol), H14[NaP5W30O110] (0.1 mol%), and methanol (10 ml)
were refluxed to afford the corresponding alcohols and phenols. The cleavage

3106
M. M. Heravi et al.
of THP ethers and regeneration of alcohols and phenols were monitored by
TLC and GC. After completion of the reaction, the reaction mixture was
filtered. Concentration of filterate followed by column chromatography
afforded pure products.
REFERENCES
1. Greene, T. W.; Wuts, P. G. Protective Groups in Organic Synthesis, 2nd ed.; John
Wiley & Sons: New York, 1999, and references cited therein.
2. Bernady, K. F.; Wiess, M. J. Prostaglandins and congeners, 20: Synthesis of
prostaglandins via conjugate addition of lithium trans-1-alkenyltrialkylalanate
reagents: A novel reagent for conjugate 1,4-additions. J. Org. Chem. 1979, 44,
1438.
3. Namboodiri, V. V.; Varma, R. S. Solvent-free tetrahydropyranylation (THP) of
alcohols and phenols and their regeneration by catalytic aluminum chloride hexa-
hydrate. Tetrahedron Lett. 2002, 43, 1143.
4. Ballini, R.; Bigi, F.; Carloni, S.; Magg, R.; Sartori, G. Solvent free tetrahydropyr-
anylation of phenols and alcohols over zeolites HSZ as reusable catalysts. Tetra-
hedron Lett. 1997, 38, 4169.
5. Ranu, B. C.; Saha, M. A. Simple, efficient, and selective method for tetrahydropyr-
anylation of alcohols on a solid phase of alumina impregnated with zinc chloride.
J. Org. Chem. 1994, 59, 8269.
6. Namboodiri, V. V.; Varma, R. S. Microwave-assisted preparation of dialkylimida-
zolium tetrachloroaluminates and their use as catalysts in the solvent-free tetrahy-
dropyranylation of alcohols and phenols. Chem. Commun. 2002, 342.
7. Habibi, M. H.; Tangestaninejad, S.; Mohammadpoor-Baltork, I.; Mirkhani, V.;
Yadollahi, B. Potassium dodecatangestocobaltate trihydrate (K5CoW12
.
O40 3H2O): A mild and efficient catalyst for the tetrahydropyranylation of
alcohols and their detetrahydropyranylation. Tetrahedron Lett. 2001, 42, 2851.
8. Molnar, A.; Berogszaszi, T. Mild and efficient tetrahydropyranylation and deprotec-
tion of alcohols catalyzed by heteropoly acids. Tetrahedron Lett. 1996, 37, 8597.
9. Dachamuthu, K.; Vankar, Y. D. Ceric ammonium nitrate-catalyzed tetrahydropyr-
anylation of alcohols and synthesis of 2-deoxy-o-glycosides. J. Org. Chem. 2001,
66, 7511.
10. Heravi, M. M.; Behbahani, F. K.; Oskooiee, H. A.; Hekmatshoar, R. Mild and
efficient tetrahydropyranylation of alcohols and dehydropyranylation of ethers
catalyzed by ferric perchlorate. Tetrahedron Lett. 2005, 46, 2543.
11. Heravi, M. M.; Ajami, D.; Ghassemzadeh, M. Solvent free tetrahydropyranylation
of alcohols and phenols with sulfuric acid absorbed on silica gel. Synth. Commun.
1999, 29, 1013.
12. Niaki, T. T.; Oskooiee, H. A.; Heravi, M. M.; Miralaee, B. Oxidative deoximation
by supported bismuth(III) nitrate mediated by DABCO under microwave
irradiation. J. Chem. Res., Synop. 2004, 7, 488.
13. Heravi, M. M.; Taheri, S.; Bakhtiari, K.; Oskooie, H. A. Cupric sulfate Pentahy-
drate: A mild and efficient catalyst for the chemoselective synthesis of 1,1-
diacetate from aldehydes in solvent-free system. Monatsh. Chem. 2006, 137, 1075.
14. Heravi, M. M.; Tagbakhsh, M.; Ahmadi, A. N.; Mohagerani, B. Efficient and eco-
friendly catalyst for the synthesis of benzimidazoles. Manats 2006, 137, 175.

Tetrahydropyranylation of Alcohols and Phenols
3107
15. Heravi, M. M.; Bakhtiari, K.; Taheri, S.; Oskooie, H. A. KHSO4: A catalyst for
chemoselective preparation of 1,1-diacetate from aldehydes under solvent-free
condition. Green. Chem. 2005, 7, 667.
16. Heravi, M. M.; Derikvand, F.; Haghighi, M.; Bakhtiari, K. “On water”:
Rapid Knoevenagel condensation using sodium pyruvate. Lett. Org. Chem.
2006, 3, 297.
17. Heravi, M. M.; Derikvand, F.; Oskooie, H. A.; Hekmat Shoar, R. Silica gel–
supported bis(trimethylsilyl) Chromate: Oxidation of 1,4-dihydropyridines to
pyridines. Synth. Comm. 2006, 36, 77.
18. Heravi, M. M.; Derikvand, F.; Bamoharram, F. F. A catalytic method for synthesis
of Biginelli-type 3,4-dihydropyrimidin-2(1H)-one using 12-tungstophosphoric
acid. Mol. Catal. A: Chem. 2005, 242, 173.
19. Heravi, M. M.; Bakhtiari, K.; Bamoharram, F. F. 12-Molybdophosphoric acid: A
recyclable catalyst for the synthesis of Biginelli-type 3,4-dihydropyrimidine-
2(1H)-ones. Catal. Commun. 2006, 7, 373.
20. Bamoharram, F. F.; Heravi, M. M.; Roshani, M.; Jahangir, M.; Gharib, A.
Preyssler catalyst, [NaP5W30O110]
142: A green, efficient and reusable catalyst for
esterification of salicylic acid with aliphatic and benzylic alcohols. Appl. Catal.
2006, 302, 42.
21. Heravi, M. M.; Motamedi, R.; Seifi, N.; Bamoharram, F. F. Catalytic synthesis of
6-aryl-1H-pyrazolo[3,4-d]pyrimidin-4[5H]-ones by heteropolyacid: H14[NaP5
W30O110] and H3PW12O40. Mol. Catal. A: Chem. 2006, 249, 1.