Mild and efficient chemoselective tetrahydropyranylation of alcohols using bronsted acidic ionic liquid as catalyst under solvent-free conditions

Article abstract of DOI:10.1080/00397911.2010.551286

A straightforward and efficient method for preparation of morpholinium bisulfate ([mroH]HSO₄) as a novel acidic ionic liquid is reported. The application of this efficient and inexpensive acidic ionic liquid catalyst for tetrahydropyranylation of alcohols under mild and solvent-free conditions at room was investigated.

Full text of DOI:10.1080/00397911.2010.551286

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Mild and Efficient Chemoselective
Tetrahydropyranylation of Alcohols Using
Brønsted Acidic Ionic Liquid as Catalyst
Under Solvent-Free Conditions
Abdol R. Hajipour a b & Zahra Nasresfahani b
a Department of Pharmacology, University of Wisconsin, Medical
School, Madison, Wisconsin, USA
b Pharmaceutical Research Laboratory, Department of Chemistry,
Isfahan University of Technology, Isfahan, Iran
Available online: 27 Oct 2011
To cite this article: Abdol R. Hajipour & Zahra Nasresfahani (2012): Mild and Efficient Chemoselective
Tetrahydropyranylation of Alcohols Using Brønsted Acidic Ionic Liquid as Catalyst Under Solvent-Free
Conditions, Synthetic Communications: An International Journal for Rapid Communication of Synthetic
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Synthetic Communications1, 42: 1995–2006, 2012
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2010.551286
MILD AND EFFICIENT CHEMOSELECTIVE
TETRAHYDROPYRANYLATION OF ALCOHOLS USING
BRØNSTED ACIDIC IONIC LIQUID AS CATALYST
UNDER SOLVENT-FREE CONDITIONS
Abdol R. Hajipour1,2 and Zahra Nasresfahani2
1Department of Pharmacology, University of Wisconsin, Medical School,
Madison, Wisconsin, USA
2Pharmaceutical Research Laboratory, Department of Chemistry, Isfahan
University of Technology, Isfahan, Iran
GRAPHICAL ABSTRACT
Abstract A straightforward and efficient method for preparation of morpholinium bisulfate
([mroH]HSO4) as a novel acidic ionic liquid is reported. The application of this efficient
and inexpensive acidic ionic liquid catalyst for tetrahydropyranylation of alcohols under
mild and solvent-free conditions at room was investigated.
Keywords Alcohols; Brønsted acidic; ionic liquid; OTHP; protection
INTRODUCTION
Tetrahydropyranyl (THP) ether is one of the most versatile protecting groups
for alcohols in modern organic syntheses because it is stable under a variety of reac-
tion conditions such as alkaline media and toward Grignard and alkyl lithium
reagents, oxidative reagents, as well as alkylating and acylating reagents.[1] Different
methods have been reported for tetrahydropyranylation of alcohols including
employing Brønsted[2] or Lewis acids,[3] ion-exchange resins,[4] LiOTf,[5] K5CoW12-
O4 ꢀ 3H2O,[6] CuSO4 ꢀ 5H2O,[7] In(OTf)3,[8] PdCl2(CH3CN)2,[9] ZnCl2,[10] I2,[11] silica
chloride,[12] tetrabutylammonium tribromide,[13] zirconium sulfophenyl phospho-
nate,[14] ionic liquids,[15] zeolites,[16] and K-10 clay.[17]
Although these methods are quite useful in many synthetic transformations,
many of the reported methods suffer from drawbacks such as long reaction time
Received November 6, 2010.
Address correspondence to Abdol R. Hajipour, Pharmaceutical Research Laboratory, Department
of Chemisty, Isfahan University of Technology, Isfahan 84156, Iran. E-mail: haji@cc.iut.ac.ir
1995

1996
A. R. HAJIPOUR AND Z. NASRESFAHANI
Scheme 1. Preparation of [morH]HSO4.
and harsh reaction conditions. Therefore, there is still need for a milder, neutral, and
efficient alternative for the protection of hydroxyl groups as THP ethers.
Recently ionic liquid (IL) technology has offered new and environmentally
benign approach to green chemistry[18] and has been successfully employed in organic
chemistry synthesis.[19] ILs have some advantages such as low vapor pressure, thermal
stability, reusability, and the ability to dissolve many organic and inorganic
substrates.[20] Also, ILs have successfully been employed as dual reagents (solvents þ
catalytic) in various reactions, but their application as catalyst under solvent-free
conditions need more attention.[21] Ionic liquids with acidic counterions such as
1-hexyl-3-methyl-imidazolium bisulfate ([hmim][HSO4]),[22] 1-butyl-3-methyl-imida-
zolium dihydogen phosphate ([bmim][H2PO4]),[5] 1-[2-(2-hydroxy-ethoxy)ethyl]-
3-methyl-imidazolium bisulfate ([heemim][HSO4]),[23] 1-butyl-3-methyl-imidazolium
chloroaluminate ([bmim]Cl ꢀ 2AlCl3),[24] and 1-butyl-3-methyl-imidazolium bisulphate
([bmim][HSO4])[25] have been used as acid catalysts.
In continuation of our effort to develop new methods in organic transforma-
tions,[26–28] here we report a new, mild, and efficient method for tetrahydropyranyla-
tion of alcohols using dihydro-4H-pyran (DHP) in the presence of a catalytic amount
of ionic liquid [morH]HSO4 at room temperature. As demonstrated in Scheme 1, the
acidic ionic liquid was prepared by adding a stoichiometric amount of concentrated
sulfuric acid to morpholine at 0 ꢁC.
RESULTS AND DISCUSSION
To optimize the reaction conditions, initially we tried the protection of benzyl
alcohol with 3,4-dihydropyran using different amounts of [morH]HSO4 in various
solvents and also under solvent-free conditions. The best results for tetrahydropyr-
anylation of benzyl alcohol were found using 10 mol% of catalyst. As shown in
Table 1, in comparison to conventional methods the yields of the reaction under
solvent-free conditions were greater in less time.
The optimized conditions were employed for protection of various alcohols to
the corresponding pyranyl ethers (Scheme 2, Table 2).
As shown in Table 2, a wide range of alcohols including primary, secondary,
=
allylic, and benzylic alcohols with different functional groups such as C C, Cl,
OMe and NO2 were converted to the corresponding tetrahydropyranyl ether
(OTHP) in good to excellent yields in the presence of a catalytic amount of
[morH]HSO4. It is noteworthy that all of the reactions were completed in short times
at room temperature. Primary benzylic alcohols with electron-donating and

PROTECTION OF ALCOHOLS
1997
Table 1. Conversion of benzyl alcohol to its corresponding tetrahydropyranyl ethers in different solvents
and under solvent-free conditions in the presence of [morH] HSO4
Entry
Solventa
Yieldb (%)
Time (min)
1
2
3
4
5
Dichloromethane
Cyclohexane
Ethyl acetate
Acetonitrile
50
60
30
80
90
60
60
60
60
3
Solvent-free
aThe reaction was carried out in 3 mL of solvent.
bThe yield refer to isolated pure product or GC analysis.
electron-withdrawing groups were tetrahydropyranylated, and the corresponding
tetrahydropyranyl ethers were obtained in good to excellent yields (Table 2, entries
2–9). However, the secondary benzylic alcohols were tetrahydropyranylation with
lower yields (Table 2, entries 10–12). Allylic alcohols were also converted to their
corresponding tetrahydropyranyl ethers in good yields without any elimination pro-
=
duct by isomerization of C C bonds (entry 13). Tetrahydropyranylation of linear
and cyclic saturated primary and secondary alcohols were also investigated
(Table 2, entries 14–17). Phenol did not undergo pyranylation under these conditions
(Table 2, entry 18).
To show the merit of the present work in comparison with recently reported
protocols, we compared the results of the tetrahydropyranylation of benzyl alcohol
with the best of the well-known data from the literature (Table 3). As demonstrated
in Table 3, our method is superior to the previously reported procedure from the
point of view of using inexpensive reagent, straightforward isolation of products,
and reaction under solvent-free and green conditions at room temperature.
To examine the chemoselectivity of the present method, one equimolar ratio of
symmetrical diols and 3,4-dihydro-2H-pyran were allowed to react in the presence of
[morH]HSO4. As shown in Table 4, (entries 1 and 2), this method showed chemos-
electivity for the monotetrahydropyranylation of diols.
The possible mechanism for the tetrahydropyranylation of alcohols with
3,4-dihydropyran is illustrated in Scheme 3. Bisulfate anion initiates the tetrahydro-
pyranylation of alcohol by protonation of 3,4-dihydropyran, the hydroxyl group
attacks to the protonated 3,4-dihydropyran, and finally the bisulfate counteranion
regenerates.
Scheme 2. Pyranylation of alcohols under solvent-free conditions at room temperature.

1998
A. R. HAJIPOUR AND Z. NASRESFAHANI
Table 2. Tetrahydropyranylation of alcohols using DHP in the presence of [morH]HSO4 under
solvent-free conditions at room temperature
Entry
1
Substrate
Product
Time (min)
3
Yield[ref] (%)a,b
90[30]
2
3
91[31]
3
4
2
3
93[31]
95[29]
5
6
4
3
87[31]
85[31]
7
8
4
3
90[29]
85[29]
9
3
4
94[31]
10
93
11
5
70[29]
12
13
5
3
65
91[30]
(Continued )

PROTECTION OF ALCOHOLS
1999
Table 2. Continued
Entry
14
Substrate
Product
Time (min)
4
Yield[ref] (%)a,b
85[31]
15
3
87
16
17
4
3
90[31]
83[31]
18
18
10
85[29]
45
0
aThe yields refer to the isolated pure products or GC analysis.
bProducts were characterized by spectroscopic data (FTIR, 1H NMR, and 13C NMR).
Table 3. Comparison of the activity of various catalysts for tetrahydropyranylation of benzyl alcohol
Entry
Catalyst
Conditions
DHP=Cat.
Time
Yield (%)
Ref.
1
2
3
4
5
6
7
[morH]HSO4
K5CoW12O40
Ps–AlCl3
Solvent-free, rt
Aceton, rt
1.2:0.09
2:0.01
3 min
5 min
0.7 h
1 h
90
97
This work
[13]
[22]
CH2Cl2, rt
CH2Cl2, rt
Solvent-free, 30 ꢁc
Et2O, rt
1.2–1.5:0.15
1:0.02
97
85
TBATB
[14]
[10]
AlCl3,6H2O
Fe(ClO4)3
PdCl2(CH3PCN)2
1.1:0.03
1:0.02
1.1:0.1
5 min
1.5 h
1 h
100
98
[26]
[27]
THF, rt
72
Table 4. Competitive tetrahydropyranylation of alcohols by using [morH] HSO4
under solvent-free conditionsa
½morHꢃHSO4
Near;rt
1
2
HOCH2CH2OH þ DHP ꢂ! HOCH2CH2OTHP þ THPOCH2CH2OTHP
2 mmol
85% 15%
2 mmol
½morHꢃHSO4
Near;rt
HOðCH2Þ4OH þ DHP ꢂ! HOðCH2Þ4OTHP þ THPOðCH2Þ4OTHP
2 mmol
2 mmol
90%
10%
aThe progress of the reaction was determined by GC and TLC analysis.

2000
A. R. HAJIPOUR AND Z. NASRESFAHANI
Scheme 3. Mechanism of protection of alcohols using [morH]HSO4.
CONCLUSION
In conclusion, we have developed a straightforward, efficient, and mild process
for tetrahydropyranylation of alcohols using [morH]HSO4 as an efficient catalyst.
Alcohols were chemoselectively tetrahydropyranylated in the presence of phenols
at room temperature. The mild reaction conditions, reaction under solvent
free-conditions without using volatile solvents, short reaction times, good to excel-
lent yields, low cost, easy preparation and handling, and relatively nontoxic acidic
catalyst are other advantages of this method.
EXPERIMENTAL
All reagents were purchased from Merck and Aldrich and used without further
purification. All yields refer to isolated products after purification. Products were
characterized by comparison with authentic samples and by spectroscopic data
1
1
[Fourier transform–infrared (FTIR), H NMR, and 13C NMR]. H NMR spectra
were recorded at 300 MHz in CDCl3 relative to tetramethylsilane (TMS) as an
internal standard.
Preparation of Morpholinium Bisulfate [morH]HSO4
A 25-mL, round-bottom flask was charged with morpholine (0.87 mL,
10 mmol) and cooled to 0 ꢁC. Then, a stoichiometric amount of concentrated sulfuric
acid (97%, 0.53 mL, 10 mmol) was added dropwise to the reaction mixture at 0 ꢁC,
and the mixture was stirred for 10 min at 0 ꢁC and then stirred for 20 min at room
temperature. The acidic IL was washed repeatedly with cyclohexane (3 ꢄ 3 mL) to
remove non-IL residue and dried under reduced pressure to produce the pure acidic
IL in 80% yields (1.12 g, 8 mmol). FT-IR (KBr): 3275–2150 (br), 1560, 1450, 1420,

PROTECTION OF ALCOHOLS
2001
1300, 1170, 1100, 1070, 1009, 870, 576. 1H NMR (DMSO, TMS) d 3.0 (m, 4H), 3.8.
(s, 4H), 7.2 (s, 2H), 8.8 (s, 1H) ppm. 13C NMR (DMSO, TMS) d: 43 (2 C), 63 (2C).
EMS [M þ Hþ], calcd. 186.0558. Found 186.1841.
Typical Procedure for Preparation of Benzyltetrahydropyranyleter in
the Presence of a Catalytic Amount of [morH]HSO4
To a stirred solution of benzyl alcohol (0.1 ml, 1 mmol) and 3,4-dihydropyran
(0.1 g, 1.2 mmol) was added [morH]HSO4 (0.018 g, 0.1 mmol, 10 mol%). The reaction
mixture was stirred at room temperature, and the progress of the reaction was mon-
itored by thin-layer chromatography (TLC) (n-hexane=EtOAc, 75:25). After com-
pletion of the reaction, the mixture was diluted with dichloromethane, and the
solid was filtered off. The organic layer was washed with water and dried over anhy-
drous Na2SO4. The solvent was evaporated under reduced pressure, and the residue
was purified by column chromatography (silica gel, cyclohexane=ethyl acetate,
75=25) to afford the tetrahydropyranyl ether of benzyl alcohol in 90% yield
1
(0.16 g, 0.9 mmol). H NMR (CDCl3, TMS) d 1.4–3.0 (m, 6H, 3CH2), 3.4–4.0 (m,
2H, CH2O), 4.4–4.8 (dd, 2H, PhCH2O), 4.7 (t, 1H, O–CH–O), 7.5 (s, 5H, C6H4);
FT-IR (KBr): 3028, 2940, 2870, 1500, 1450, 1350, 1260, 1200, 1120, 1070, 1026,
970, 870, 730, 700 cmꢂ1
.
Selected Data
2-(Benzyloxy)tetrahydro-2H-pyran. IR (KBr): 2942, 2903, 2877, 1592,
1
1490, 1399, 1131, 1025, 1038 cmꢂ1. H NMR (400 MHz, CDCl3): d 7.25 (b, 5 H),
4.80 (d, J ¼ 12.4 Hz, 1 H, ArCH), 4.70 (br s, 1 H, OCHO), 4.42 (d, J ¼ 11.6 Hz, 1
H, ArCH), 3.89 (t, J ¼ 8.4 Hz, 1 H, OCH2), 3.52 (d, J ¼ 11.2 Hz, 1 H, OCH2),
1.90–1.44 (m, 6 H, CH2). 13C NMR (100 MHz, CDCl3): d 138.50, 128.50, 128.04,
127.71, 97.90, 69.10, 62.40, 31.00, 25.90, 19.80.
2-(2-Methoxybenzyloxy)tetrahydro-2H-pyran. IR (KBr) 2940, 2893, 1591,
1423, 1395, 13.52, 1271, 1209, 1131, 1127 cmꢂ1. 1H NMR (400 MHz, CDCl3): d 7.28
(m, 4 H), 4.69 (d, J ¼ 12.4 Hz, 1 H, ArCH), 4.69 (br s, 1 H, OCHO), 4.42 (d,
J ¼ 12.0 Hz, 1 H, ArCH), 3.90 t, J ¼ 8.4 Hz, 1 H, OCH2), 3.76 (s, 3 H), 3.30 (d,
J ¼ 11.2 Hz, 1 H, OCH2), 1.89–1.49 (m, 6 H, CH2). 13C NMR (100 MHz, CDCl3):
d 159.21, 130.81, 128.80, 129.27, 97.73, 68.80, 62.40, 53.60, 30.70, 25.41, 19.80.
2-(3-Methoxybenzyloxy)tetrahydro-2H-pyran. IR (KBr) 2940, 2893, 1591,
1423, 1395, 13.52, 1271, 1209, 1131, 1127 cmꢂ1. 1H NMR (400 MHz, CDCl3): d 7.28
(m, 4 H), 4.69 (d, J ¼ 12.4 Hz, 1 H, ArCH), 4.69 (br s, 1 H, OCHO), 4.42 (d,
J ¼ 12.0 Hz, 1 H, ArCH), 3.90 t, J ¼ 8.4 Hz, 1 H, OCH2), 3.76 (s, 3 H), 3.30 (d,
J ¼ 11.2 Hz, 1 H, OCH2), 1.91–1.46 (m, 6 H, CH2). 13C NMR (100 MHz, CDCl3):
d 159.21, 130.81, 128.80, 129.27, 97.73, 68.80, 62.40, 53.60, 30.70, 25.41, 19.80.
2-(4-Methoxybenzyloxy)tetrahydro-2H-pyran. IR (KBr) 2940, 2893, 1591,
1423, 1395, 13.52, 1271, 1209, 1131, 1127 cmꢂ1. 1H NMR (400 MHz, CDCl3): d 7.28
(d, J ¼ 8.8 Hz, 2 H), 6.87 7.28 (d, J ¼ 8.8 Hz, 2 H), 4.76 (d, J ¼ 12.4 Hz, 1 H, ArCH),
4.65 (br s, 1 H, OCHO), 4.46 (d, J ¼ 12.0 Hz, 1 H, ArCH), 3.98 (s, 3H), 3.89 (t,

2002
A. R. HAJIPOUR AND Z. NASRESFAHANI
J ¼ 8.4 Hz, 1 H, OCH2), 3.51 (d, J ¼ 11.2 Hz, 1 H, OCH2), 1.89–1.54 (m, 6 H, CH2).
13C NMR (100 MHz, CDCl3): d 159.2, 136.81, 133.44, 128.80, 128.27, 97.73, 67.80,
61.90, 52.70, 30.70, 25.41, 19.40.
2-(2-Chlorobenzyloxy)tetrahydro-2H-pyran. IR (KBr) 2940, 2893, 1591,
1423, 1395, 13.52, 1271, 1209, 1131, 1127, 1025, 977, 916 cmꢂ1 1H NMR
.
(400 MHz, CDCl3): d 7.55–7.25 (b, 4 H), 4.78 (d, J ¼ 12.4 Hz, 1 H, ArCH), 4.65
(br s, 1 H, OCHO), 4.42 (d, J ¼ 12.0 Hz, 1 H, ArCH), 3.98 (s, 3H), 3.89 (t, J ¼ 8.4 Hz,
1 H, OCH2), 3.51 (d, J ¼ 11.2 Hz, 1 H, OCH2), 1.89–1.49 (m, 6 H, CH2). 13C NMR
(100 MHz, CDCl3): d 136.81, 133.44, 128.80, 128.27, 97.73, 67.80, 61.90, 30.70,
25.41, 19.40.
2-(3-Chlorobenzyloxy)tetrahydro-2H-pyran. IR (KBr) 2940, 2893, 1591,
1423, 1395, 13.52, 1271, 1209, 1131, 1127, 1025, 977, 916 cmꢂ1 1H NMR
.
(400 MHz, CDCl3): d 7.55–7.25 (b, 4 H), 4.78 (d, J ¼ 12.4 Hz, 1 H, ArCH), 4.65
(br s, 1 H, OCHO), 4.42 (d, J ¼ 12.0 Hz, 1 H, ArCH), 3.98 (s, 3H), 3.89 (t, J ¼ 8.4 Hz,
1 H, OCH2), 3.51 (d, J ¼ 11.2 Hz, 1 H, OCH2), 1.89–1.54 (m, 6 H, CH2). 13C NMR
(100 MHz, CDCl3): d 136.81, 133.44, 128.80, 128.27, 97.73, 67.80, 61.90, 30.70,
25.41, 19.40.
2-(4-Chlorobenzyloxy)tetrahydro-2H-pyran. IR (KBr) 2940, 2893, 1591,
1423, 1395, 13.52, 1271, 1209, 1131, 1127, 1025, 977, 916 cmꢂ1 1H NMR
.
(400 MHz, CDCl3): d 7.55–7.25 (b, 4 H), 4.78 (d, J ¼ 12.4 Hz, 1 H, ArCH), 4.65
(br s, 1 H, OCHO), 4.42 (d, J ¼ 12.0 Hz, 1 H, ArCH), 3.98 (s, 3H), 3.89 (t, J ¼ 8.4 Hz,
1 H, OCH2), 3.51 (d, J ¼ 11.2 Hz, 1 H, OCH2), 1.89–1.54 (m, 6 H, CH2). 13C NMR
(100 MHz, CDCl3): d 136.81, 133.44, 128.80, 128.27, 97.73, 67.80, 61.90, 30.70,
25.41, 19.40.
2-(4-Nitrobenzyloxy)tetrahydro-2H-pyran. IR (KBr) 2940, 2893, 1591,
1423, 1395, 13.52, 1271, 1209, 1131, 1127, 1025, 977, 814 cmꢂ1 1H NMR
.
(400 MHz, CDCl3): d 8.8 (d, J ¼ 8.8 Hz, 2 H), 6.15 (d, J ¼ 8.8 Hz, 2 H), 7.25 (d, 2
H), 4.78 (d, J ¼ 12.4 Hz, 1 H, ArCH), 4.65 (br s, 1 H, OCHO), 4.42 (d, J ¼ 12.0 Hz,
1 H, ArCH), 3.98 (s, 3H), 3.89 (t, J ¼ 8.4 Hz, 1 H, OCH2), 3.51 (d, J ¼ 11.2 Hz, 1 H,
OCH2), 1.85–1.50 (m, 6 H, CH2). 13C NMR (100 MHz, CDCl3): d 156.7. 130.80,
131.50, 128.80, 128.27, 112.98, 97.7368.80, 53.60, 30.70, 25.41, 19.80.
2-(3,4-Dimethoxybenzyloxy)tetrahydro-2H-pyran. IR (KBr) 2940, 2893,
1
1591, 1423, 1395, 13.52, 1271, 1209, 1131, 1127 cmꢂ1. H NMR (400 MHz, CDCl3):
d 7.28–6.55 (m, 3 H), 4.76 (d, J ¼ 12.4 Hz, 1 H, ArCH), 4.65 (br s, 1 H, OCHO), 4.46
(d, J ¼ 12.0 Hz, 1 H, ArCH), 3.86 (s, 6H), 3.89 (t, J ¼ 8.4 Hz, 1 H, OCH2), 3.51 (d,
J ¼ 11.2 Hz, 1 H, OCH2), 1.89–1.54 (m, 6 H, CH2). 13C NMR (100 MHz, CDCl3): d
149.2, 136.81, 133.44, 128.80, 128.27, 97.73, 67.80, 61.90, 52.70, 30.70, 25.41, 19.40.
2-(1-(4-Chlorophenyl)ethoxy)tetrahydro-2H-pyran. IR (KBr) 2940, 2893,
1
1591, 1423, 1395, 13.52, 1271, 1209, 1131, 1127 cmꢂ1. H NMR (400 MHz, CDCl3):
d7.42 (d, J ¼ 8.8, 2 H), 7.30 (d, J ¼ 8.8, 2 H), 4.90 (m, 1H), 4.40 (m, 1 H), 3.98 (m, 1
H), 3.50 (m, 1 H), 1.98–1.40 (m, 9 H). 13C NMR (100 MHz, CDCl3): d 152.20,
143.80, 128.31, 127.12, 126.60, 96.32, 73.55, 63.04, 31.24, 25.98, 24.80, 20.23. Anal.
calcd. for C13H17ClO2: C, 64.86; H, 7.12. Found: C, 64.33; H, 7.32%.

PROTECTION OF ALCOHOLS
2003
2-(Benzhydryloxy)tetrahydro-2H-pyran. IR (KBr) 2942, 2963, 2877,1491,
1
1199, 1121, 1025, 977, 916 cmꢂ1. H NMR (400 MHz, CDCl3): d736–7.17 (m, 10
H), 5.79 (s, 1 H), 4.66 (t, J ¼ 3.6, 1 H), 3.91–3.85 (m, 1 H), 3.52–3.47 (m, 1 H),
1.97–152 (m, 6 H). 13C NMR (100 MHz, CDCl3): d 128.29, 128.03, 127.52, 127.43,
126.88, 126.96, 95.37, 78.5, 61.94, 30.64, 25.65, 19.27.
2-((4-Chlorophenyl)(phenyl)methoxy)tetrahydro-2H-pyran. IR
.
(KBr)
2943, 2968, 2871, 1493, 1189, 1124, 1015, 977, 916 cmꢂ1 1H NMR (400 MHz,
CDCl3): d 7.36–7.17 (m, 9 H), 5.79 (s, 1 H), 4.66 (t, J ¼ 3.6, 1 H), 3.91–3.85 (m, 1
H), 3.52–3.47 (m, 1 H), 1.97–152 (m, 6 H). 13C NMR (100 MHz, CDCl3): d
128.29, 128.03, 127.52, 127.43, 126.88, 126.96, 95.37, 78.5, 61.94, 30.64, 25.65,
19.27. Anal. calcd. for C18H19ClO2: C, 71.40; H, 3.32%. Found: C, 71.26; H, 6.35%.
2-(Cinnamyloxy)tetrahydro-2H-pyran. IR (KBr) 3020, 2940, 2893, 1591,
1423, 1395, 13.52, 1271, 1209, 1131, 1127, 1025, 977, 916 cmꢂ1 1H NMR
.
(400 MHz, CDCl3): d 7.40–7.25 (m, 5 H), 6.25 (d, J ¼ 11.24, 1 H), 6.25 (m, 1 H),
4.88 (d, J ¼ 12.4 Hz), 4.65 (m, 2 H), 3.68 (m, 2H), 3.89 (t, J ¼ 8.4 Hz, 1 H, OCH2),
1.88–1.49 (m, 6 H). 13C NMR (100 MHz, CDCl3): d 136.60, 132.21, 128.30,
127.40, 126.30, 125.80, 97.62, 67.45, 62.08, 30.40, 25.33, 19.43.
2-Phenethoxytetrahydro-2H-pyran. 2940, 2893, 1591, 1423, 1395, 1352,
1271, 1209, 1131, 1127, 1025, 977, 916 cmꢂ1 1H NMR (400 MHz, CDCl3): d
.
7.48–7.29 (m, 5 H), 4.65 (m, 1 H), 3.80 (m, 4 H), 2.79 (t, J ¼ 3.6 Hz, 2 H),
1.84–1.44 (m, 14 H). 13C NMR (100 MHz, CDCl3): d 138.90, 128.15, 126.04,
98.53, 68.10, 62.00, 36.25, 30.50, 25.30, 19.39.
2-(2-Methoxycyclohexyloxy)tetrahydro-2H-pyran. IR (neat) 2940, 2890,
1
1452, 1374, 1352, 1271, 1209, 1131, 1127 cmꢂ1. H NMR (400 MHz, CDCl3): d
4.68 (m, 1 H), 3.65 (m, 2 H), 3.30 (s, 3 H), 1.164–1.49 (m, 6 H). 13C NMR
(100 MHz, CDCl3): d 1.62, 84.93, 78.50, 63.25, 57.40, 31.23, 28.65, 28.50, 24.45,
20.12. Anal. calcd. for C16H22O2: C, 78.01; H%, 9.00. Found: C, 78.34; H, 9.19%.
2-Isopropoxytetrahydro-2H-pyran. IR (neat) 2940, 2890, 1374, 1352, 1271,
1
1209, 1127 cmꢂ1. H NMR (400 MHz, CDCl3): d 4.65 (m, 1 H), 3.60 (m, 4 H), 3.37
(m, 2 H), 1.165–1.49 (m, 6 H), 1.13 (d, J ¼ 3.8, 6 H). 13C NMR (100 MHz, CDCl3): d
104.91, 74.58, 63.17, 30.26, 25.44, 21.70, 10.30.
2-(4-Chlorobutoxy)tetrahydro-2H-pyran. IR (neat) 2940, 2890, 1374, 1352,
1271, 1209, 1127, 780, 624 cmꢂ1. 1H NMR (400 MHz, CDCl3): d 4.59 (m, 1 H), 3.66
(m, 2 H), 3.21 (m, 1 H), 1.65–1.44 (m, 10 H). 13C NMR (100 MHz, CDCl3): d 106.31,
68.20, 62.12, 33.92, 31.20, 28.14, 26.20, 19.70.
2-((1S,2S,5R)-2-Isopropyl-5-methylcyclohexyloxy)tetrahydro-2H-pyran. IR
1
(neat) 2940, 2890, 14.52, 1374, 1352, 1271, 1209, 1127 cmꢂ1. H NMR (400 MHz,
CDCl3): d 4.80–4.58 (m, 1 H), 4.00–3.86 (m, 1 H), 3.50–3.28 (m, 2 H), 2.37–2.05
(m, 2 H), 1.83), 1.10–0.76 (m, 12 H). 13C NMR (100 MHz, CDCl3): d 101.22,
94.40, 79.90, 40.16, 34.65, 34.40, 31.83, 31.45, 31.20, 25.62, 25.50, 25.24, 23.30,
23.10, 22.34, 22.20, 21.27, 21.10, 20.23, 16.30, 15.60.

2004
A. R. HAJIPOUR AND Z. NASRESFAHANI
ACKNOWLEDGMENTS
We gratefully acknowledge the funding support received for this project from
the Isfahan University of Technology (IUT), Iran (A. R. H.). Further financial
support from Center of Excellency in Sensor and Green Chemistry Research
(IUT) is gratefully acknowledged.
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