Microwave irradiation assisted synthesis, alkylation reaction, and configuration analysis of aryl pyrogallol[4]arenes

Article abstract of DOI:10.1016/j.tet.2007.07.043

A series of aryl pyrogallol[4]arenes were efficiently synthesized in excellent yields by cyclocondensation of pyrogallol with aromatic aldehydes under microwave irradiation. The structures of aryl pyrogallol[4]arenes were confirmed by characterization of

Full text of DOI:10.1016/j.tet.2007.07.043

Tetrahedron 63 (2007) 9614–9620
Microwave irradiation assisted synthesis, alkylation reaction, and
configuration analysis of aryl pyrogallol[4]arenes
*
Chaoguo Yan, Weifeng Chen, Jiao Chen, Tiantian Jiang and Yong Yao
College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002, China
Received 28 February 2007; revised 9 July 2007; accepted 13 July 2007
Available online 19 July 2007
Abstract—A series of aryl pyrogallol[4]arenes were efficiently synthesized in excellent yields by cyclocondensation of pyrogallol with
aromatic aldehydes under microwave irradiation. The structures of aryl pyrogallol[4]arenes were confirmed by characterization of their ac-
ylated derivatives. Under microwave irradiation, alkylation reactions of aryl pyrogallol[4]arenes with some alkylating reagents such as n-butyl
iodide, benzyl chloride, and ethyl a-chloroacetate were also finished quickly to yield fully O-alkylated products. The 1H NMR spectra and
crystal structures showed that the acylated and alkylated aryl pyrogallol[4]arenes existed mainly in rctt (cis–trans–trans) configuration.
Ó 2007 Elsevier Ltd. All rights reserved.
1. Introduction
chemistry has been witnessed with much great progress.
Lewis acid such as ytterbium triflate has been utilized to pro-
vide an atom economic synthesis of resorcinarenes.21,22
Scott23 and Raston24 reported solvent-free synthesis of aryl
calix[4]resorcinarenes and C-methylcalix[4]resorcinarene
by simply grinding together resorcinol with aldehydes in
the presence of a catalytic amount of p-toluenesulfonic
acid. The boron trifluoride catalyzed reaction of 3-alkoxy-
phenol with aldehydes provides an efficient method for
preparing tetraalkyloxyresorcinarenes.25 Hamdi26 initiated
microwave-assisted synthesis of calix[4]resorcinarenes by
cyclocondensation of various aldehydes with resorcinol
catalyzed with 12-tungstophosphoric acid. Viswanathan
also reported efficient synthesis of chiral calixasalens, which
displayed calixarene-like crystal structures with microwave
irradiation.27 These green routes provide fast, simple, high-
yielding, and non-polluting synthetic methodology of resor-
cinarenes and these efficient processes should be potentially
applicable to the preparation of other calixarene systems. In
continuation of our effects to develop more efficient proce-
dure for new synthetic methods and functional modification
of calixarenes, herein we wish to report microwave irradia-
tion assisted synthesis of aryl pyrogallol[4]arenes and their
O-alkylation reactions.
Pyrogallol[4]arene,1 also called as hydroxyresorci[4]arene,2
is a subgroup of calixarenes. Because of their favorable
cyclic shape, 12 hydroxyl groups, and high polarity,
pyrogallol[4]arenes have been used extensively as starting
material for carcerand synthesis,3,4 self-assembly to molecu-
lar vesicle, capsules, and other supramolecular architec-
tures5–7 as well as in liquid-crystal material,8 and in
complexation studies.9,10 Pyrogallol[4]arene can be easily
prepared similar to resorcinarenes in fairly high yields by
acid condensation of pyrogallol with aldehydes.11 The first
synthesis of pyrogallol[4]arenewas reported in 1980.12 Since
then a series of pyrogallol[4]arenes have been synthesized
with emphasis of using aliphatic aldehydes to give alkyl py-
rogallol[4]arenes.8,9,13–17 While the study of aryl pyrogallo-
l[4]arenes derived from the reaction of aromatic aldehydes
has attracted very little attention because aryl pyrogallo-
l[4]arenes usually have very poor solubility in common sol-
vents and thus are difficult for chemical modification and
to be used as building blocks.18 Iwanek19 developed a Lewis
acid-catalyzed template synthesis of methylene bridged me-
thoxypyrogallol[4]arene in crown conformer from reaction
of 1,2,3-trimethoxybenzene with trioxane. A larger cyclic
ethyl pyrogallol[6]arene is also separated as a minor product
in acid condensation process of pyrogallol with proponalde-
hyde.20
2. Results and discussion
Recently preparation of calixarenes by using benign
procedures effectively embracing the principles of green
The synthesis of aryl pyrogallol[4]arenes was conducted by
heating a mixture of equal molar amounts of pyrogallol with
aromatic aldehydes in 2-ethoxyethanol in the presence of
concentrated HCl under microwave irradiation for 3–
5 min. The general procedure of the synthetic reactions is
outlined in Scheme 1. All aromatic aldehydes reacted very
Keywords: Calixarene; Pyrogallol[4]arene; Pyrogallol; Microwave; Alkyl-
ation; Crystal structure.
* Corresponding author. E-mail: cgyan@yzu.edu.cn
0040–4020/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2007.07.043

C. Yan et al. / Tetrahedron 63 (2007) 9614–9620
9615
OAc
OH
OH
R
AcO
HO
OH
OAc
HO
OH
+
Ac2O
MW
HCl, MW
EtOCH2CH2OH
4
4
CHO
R
R
1
2a-2f
3a-3f
4a-f
Scheme 1. Synthesis and acylation of aryl pyrogallol[4]arenes.
smoothly under irradiation for about 3 min and gave good
yields of aryl pyrogallol[4]arenes 3a–3e (66–89%). Salicyl-
aldehyde and p-hydroxybenzaldehyde, which have not
previously been used in the preparation of pyrogallol[4]-
arenes, also gave high yields of pyrogallol[4]arenes with
four additional hydroxyl groups. Comparing with conven-
tional heating, microwave heating gives nearly same yields
and the reaction can be finished invery short time, which dem-
onstrates that aryl pyrogallol[4]arenes can be prepared simply
and efficiently under microwave irradiation condition.
anhydride. The formed acyl derivatives 4a–4e have very
good solubility in organic solvents and therefore all neces-
1
sary analytical data such as IR, H and 13C NMR spectra
as well as elemental analysis were achieved for them. In their
IR spectra, the acetyl C]O groups show a very strong ab-
sorption band at 1780 cmꢀ1 with the disappearance of hy-
droxyl absorption at 3200–3500 cmꢀ1, which indicated
that all hydroxyl groups in 3a–3e have been transformed
1
into ester groups. The H NMR spectra of 4a–4f in CDCl3
usually show one singlet peak for bridging methyne protons
at about 5.4 ppm and two singlet signs in 1:1 ratio for proton
of pyrogallol ring at about 6.0 and 6.3 ppm, which clearly in-
dicates two kinds of pyrogallol rings existed in the molecule
and 4a–4f should be in thermodynamically stable rctt (cis–
trans–trans) isomer. The proton of acyl groups usually shows
a group of peaks at 1.90–2.20 ppm, which is concordance
with the fact that the 12 acyl groups existed in slightly differ-
ent environments (Figs. 1 and 2).
Because of having at least 12 hydroxyl groups these aryl
pyrogallol[4]arenes 3a–3e have very poor solubility in
common organic solvents. It is very difficult for us to get ac-
cepted characterization data for them. For confirming their
structures, it is better to convert the hydrophilic hydroxyl
groups into ester groups, which can be done conveniently
by refluxing aryl pyrogallol[4]arenes 3a–3e in acetic
Figure 1. 1H NMR spectrum of compound 4b.
Figure 2. 1H NMR spectrum of compound 4c.

9616
C. Yan et al. / Tetrahedron 63 (2007) 9614–9620
Figure 3. Crystal structure of acylated p-methylphenyl pyrogallol[4]-
arene 4b.
Figure 4. Crystal structure of acylated p-methoxyphenyl pyrogallol[4]-
arene 4c.
The X-ray single crystal analysis of two representative com-
pounds 4b and 4c confirms the structures of the aryl pyrogal-
lol[4]arenes. The crystal structures are shown in Figures 3
and 4 and the crystal data are listed in Table 1. It is interest-
ing to find that p-methylphenyl and p-methoxyphenyl
pyrogallol[4]arenes 4b and 4c are both in rctt (cis–trans–
trans) configuration isomer, which supports the results of
the 1H NMR analysis. The four pyrogallol units in the calix-
arene ring were divided into two groups with two pyrogallol
rings at almost perpendicular direction and other two pyro-
gallol rings nearly in horizontal position. The stretching
direction of two perpendicular pyrogallol rings is opposite.
One pyrogallol ring is upper standing and the other is upside
down. The four side p-methylphenyl or p-methoxyphenyl
groups are also divided into two groups with two neighbor-
ing phenyl groups at C1 and C20 locating in upper direction,
while other two phenyl groups at C13 and C32 stretching to
down direction.
Table 1. Crystal data and structure refinement details of pyrogallol[4]arenes
4b
4c
5a
5c
5d
Empirical formula
Formula weight
Temperature (K)
Wavelength (A)
Crystal system, space group
Unit cell dimensions
C84H76Cl12O24
1894.84
273(2)
C82H74Cl6O28
1720.12
273(2)
C138H114Cl6O12
2177.00
273(2)
C140H120O16
2058.36
293(2)
C100H134O12
1528.07
273(2)
˚
0.71073
0.71073
0.71073
0.71073
0.71073
Triclinic, P-1
11.9764(16)
14.792(2)
15.545(2)
61.992(2)
74.241(2)
78.256(2)
3890.4
2
1.350
0.093
976
Triclinic, P-1
12.403(2)
12.6998(19)
15.774(2)
66.691(2)
78.585(2)
68.983(2)
2125.5(6)
2
Monoclinic, P2(1)/n
12.9584(11)
27.628(2)
16.5237(14)
90.00
92.2270(10)
90.00
5911.3(9)
4
1.223
Triclinic, P-1
14.113(2)
26.291(4)
20.786(2)
90
131.635(6)
90
5764.3(13)
2
1.186
Triclinic, P-1
13.300(2)
18.758(4)
21.464(4)
67.617(3)
77.221(3)
82.474(4)
4822.1(15)
1
3
Volume (A )
˚
Z
Calculated density (g cmꢀ3
)
1.344
0.281
892
1.052
0.067
1660
Absorption coefficient (mmꢀ1
F(000)
)
0.207
2280
0.077
2176
Crystal size (mm)
q range for data collection
hkl ranges
0.40ꢁ0.30ꢁ0.30
2.05–25.00
ꢀ12 to14, ꢀ17
to 17, ꢀ18 to 16
0.20ꢁ0.20ꢁ0.10
2.07–25.00
ꢀ9 to14, ꢀ14
to 15, ꢀ17 to 18
0.30ꢁ0.30ꢁ0.25
2.09–25.00
ꢀ15 to14, ꢀ32
to 30, ꢀ19 to 19
0.30ꢁ0.10ꢁ0.10
1.97–25.00
ꢀ16 to 15, ꢀ31
to 31, ꢀ11 to 24
0.30ꢁ0.20ꢁ0.20
1.99–25.00
ꢀ15ꢂhꢂ11,
ꢀ22ꢂkꢂ15,
ꢀ25ꢂlꢂ23
25,237/16,703
[R(int)¼0.0601]
98.4
Reflections collected/unique
8070/4789
[R(int)¼0.0202]
7365/3267
[R(int)¼0.0104]
10,395/6487
[R(int)¼0.0272]
99.7
10,137/3883
[R(int)¼0.0995]
99.7
Completeness to theta¼27.50 (%)
Absorption correction
Refinement method
98.2
None
98.4
None
None
None
None
Full-matrix least-
squares on F2
8070/0/550
1.046
R1¼0.1197,
wR2¼0.2732
R1¼0.0760,
wR2¼0.2310
0.491 and ꢀ0.533
Full-matrix least-
squares on F2
7365/6/532
1.228
R1¼0.2126,
wR2¼0.4223
R1¼0.1276,
wR2¼0.3555
1.003 and ꢀ0.557
Full-matrix least-
squares on F2
10,392/99/692
1.004
R1¼0.1254,
wR2¼0.2988
R1¼0.0861,
wR2¼0.2574
0.939 and ꢀ0.645
Full-matrix least-
squares on F2
16,858/9/665
0.930
R1¼0.2056,
wR2¼0.2234
R1¼0.0780,
wR2¼0.1782
0.415 and ꢀ0.256
Full-matrix
least-squares on F2
16,703/68/1018
0.917
R1¼0.1110,
wR2¼0.2909
R1¼0.3339,
wR2¼0.4413
0.340 and ꢀ0.388
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I>2s(I)]
R indices (all data)
ꢀ3
˚
Largest diff. peak and hole (eA
)

C. Yan et al. / Tetrahedron 63 (2007) 9614–9620
9617
Figure 5. 1H NMR spectrum of compound 5h.
OH
OR'
The O-alkylation of phenolic hydroxyl groups is the most
popular modification procedure for p-tert-butylcalixarenes
and resorcinarenes. It should be also suitable for the prepa-
ration of functional derivatives of pyrogallol[4]arene.28
Aryl resorcinarenes and pyrogallol[4]arenes have been suc-
cessfully alkylated by reaction with ethyl a-bromoacetate in
the refluxing system of K2CO3/acetone for relatively longer
time (5–7 days) to give the fully O-alkylated products in
lower yield (11–27%).29 The rapid heating induced by mi-
crowave irradiation leads to the formation of products under
mild reaction conditions with short reaction times, thus
avoiding decomposing or side reactions and, in many cases,
increasing the yields. Now there have been a lot of examples
about alkylation reactions under microwave irradiation.30 So
we try to carry microwave irradiation assisted O-alkylation
of aryl pyrogallol[4]arenes with some typical alkylating re-
agents. The reaction was carried out by heating a mixture of
aryl pyrogallol[4]arenes (3a–3c), potassium carbonate, and
alkylating reagents in DMF in the presence of polyethylene
glycol under microwave irradiation for about 3 min. After
workup the fully O-alkylation products (5a–5i) were sepa-
rated in moderate yields. All testing alkylating reagents
such as n-butyl iodide, benzyl chloride, and ethyl a-
chloroacetate gave the expected fully alkylation products
with high purity in very short time compared with the results
of conventional heating reactions. Thus this method is very
suitable for rapid preparation of some functional
pyrogallol[4]arenes. The structure of all products was char-
HO
R'O
OH
OR'
R'X, K2CO3
PEG-400, DMF, MW
4
4
R
R
Scheme 2. Alkylation reactions of pyrogallol[4]arenes.
in Table 1. It is clearly seen from Figures 6 and 7 that there
are 12 benzyl groups in the outer spherical positions of 5a
and 5c, which confirmed the correct structure of the O-alkyl-
ated products. Compounds 5a and 5c both exist in rctt isomer
or in chair form. The four pyrogallol units in the ring were
divided into two groups with two pyrogallol rings at
almost perpendicular direction and other two being nearly
in horizontal. The stretching direction of two perpendicular
pyrogallol rings is opposite. One is upper standing and the
other is upside down. The four phenyl groups in 5a and
four p-methoxyphenyl groups in 5c are also divided in two
groups with two phenyl groups at C1 and C20 locating in
upper direction, while other two phenyl groups at C13 and
C32 stretching to down direction. The fully n-butylated 5d
also exists in rctt configuration with 12 n-butyl groups
stretching to all directions.
In conclusion, we have provided microwave irradiation
assisted preparation of aryl pyrogallol[4]arenes and their
functional O-alkylating derivatives in moderate yields. The
procedure is simple, efficient and time saving, and the
1
acterized with IR, H and 13C NMR spectroscopy, and ele-
1
mental analysis. As for example in H NMR spectroscopy
of 5h (Fig. 5), the –OCH2CO– groups show a mixed peak
at about 4.30–4.80 ppm and methylene of OCH2CH3 groups
displays a broad peak at about 4.10 ppm. The sign of bridg-
ing methyne appears at about 6.8 ppm, which is much down
shifted with the data of acylated derivatives (4b). The four
protons of pyrogallol ring show two single peaks in 1:1 ratio
at about 6.0 and 5.7 ppm, which also indicates two kinds of
pyrogallol rings existed in the molecule and 5h occurs in
1
cis–trans–trans (rctt) configuration isomer. The H NMR
spectra of O-benzylated and O-butylated derivatives all
gave two singlets in 1:1 ratio for protons of pyrogallol
ring, which suggest that they all exist in cis–trans–trans
(rctt) configuration isomer (Scheme 2).
The X-ray single crystal structure of 5a, 5c, and 5d are
shown in Figures 6–8 and their crystal data are also listed
Figure 6. Crystal structure of benzylated phenylpyrogallol[4]arene 5a.

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C. Yan et al. / Tetrahedron 63 (2007) 9614–9620
dimethyl sulfoxide, alcohol, and ethyl ether) were com-
mercial reagents with analytical grade and used as received.
Further purification and drying by standard method were
employed and distilled prior to use when necessary.
3.2. General procedure for the synthesis of acylated aryl
pyrogallol[4]arenes
The mixture of pyrogallol (1.26 g, 10.0 mmol), aldehydes
2a–2f (10.0 mmol), 2-ethoxyethanol (2.0 mL), and concen-
trated HCl (2.0 mL) was heated by microwave irradiation
for about 2 min with a fixed power of 130 W. After cooling
to room temperature, 50 mL of H2O was added to the mix-
ture, the precipitate was filtered, and washed with water
and ethanol to give pink solid products 3a–3f. Then a mixture
of aryl pyrogallol[4]arenes 3a–3f (1.0 mmol) in acetic anhy-
dride (15.0 mL) and pyridine (0.5 mL) was refluxed for 8 h.
After cooling, the mixture was poured into 100 mL of water,
the organic residue extracted with chloroform (30 mL), and
dried with Na2SO4. Evaporation of the solvent gives color-
less or yellow solid, which was purified by recrystallization
with chloroform and ethyl alcohol.
Figure 7. Crystal structure of benzylated p-methoxyphenyl pyrogallol[4]-
arene 5c.
3.2.1. Compound 4a. R¼H, 83.2%, mp>250 ꢃC; 1H NMR
(CDCl3, 600 MHz) d 6.99–7.04 (m, 12H, ArH), 6.77 (s, 8H,
ArH), 6.29 (s, 2H, ArH), 5.96 (s, 2H, ArH), 5.45 (s, 4H, CH),
2.28 (s, 6H, COCH3), 2.13–2.15 (br, 18H, COCH3), 1.98 (s,
12H, COCH3); 13C NMR (CDCl3, 600 MHz) d 167.5, 166.8,
166.2, 140.5, 140.2, 138.1, 136.3, 135.9, 133.4, 133.3, 129.1,
128.8, 128.4, 126.7, 126.5, 45.1, 20.2, 20.0, 19.8; IR (KBr) n
2937 (w), 1780 (vs), 1428 (m), 1372 (s), 1203 (vs), 1041 (s),
900 (w), 872 (w), 696 (m) cmꢀ1. Anal. Calcd for C76H64O24:
C, 67.06; H, 4.74; Found: C, 66.85; H, 4.67.
1
3.2.2. Compound 4b. R¼p-CH3, 88.7%, mp>250 ꢃC; H
NMR (CDCl3, 600 MHz) d 6.86 (s, 8H, ArH), 6.66 (s, 8H,
ArH), 6.26 (s, 2H, ArH), 6.06 (s, 2H, ArH), 5.42 (s, 4H,
CH), 2.13–2.27 (m, 36H, COCH3), 1.99 (s, 12H, ArCH3);
13C NMR (CDCl3, 600 MHz) d 167.5, 166.9, 166.4, 140.4,
140.1, 136.2, 135.8, 135.7, 135.2, 133.5, 129.1, 128.9,
126.4, 44.7, 21.1, 20.2, 20.2, 20.0, 19.9; IR (KBr) n 2927
(w), 1783 (vs), 1635 (s), 1442 (s), 1376 (m), 1280 (s),
1210 (s), 1198 (vs), 1083 (s), 721 (m) cmꢀ1. Anal. Calcd
for C80H72O24: C, 67.79; H, 5.12; Found: C, 67.71; H, 4.73.
Figure 8. Crystal structure of n-butylated phenylpyrogallol[4]arene 5d.
isolation of products is simple and dispenses with extensive
recrystallization or chromatographic purification steps. The
larger quantity of functional pyrogallol[4]arenes can be
conveniently obtained in short time and it would offer great
potentials in the study of aryl pyrogallol[4]arenes. The
single crystal structure analysis of five representative
compounds indicates that aryl pyrogallol[4]arenes usually
exist in cis–trans–trans configuration isomer.
3.2.3. Compound 4c. R¼p-OCH3, 87.9%, mp>250 ꢃC; 1H
NMR (CDCl3, 600 MHz) d 6.60–6.80 (m, 16H, ArH), 6.23
(s, 2H, ArH), 5.95 (s, 2H, ArH), 5.40 (s, 4H, CH), 3.76 (s,
12H, OCH3), 1.99–2.27 (m, 36H, COCH3); 13C NMR
(CDCl3, 600 MHz) d 167.6, 166.9, 166.3, 166.2, 158.1,
140.3, 140.1, 136.1, 135.8, 133.8, 133.5, 130.3, 130.1, 128.9,
126.4, 113.7, 54.8, 44.6, 20.2, 20.2, 20.0, 19.9; IR (KBr) n
2935 (w), 1780 (vs), 1485 (w), 1435 (m), 1365 (m), 1196
(vs), 1168 (s), 1153 (s), 1027 (m), 821 (m) cmꢀ1. Anal. Calcd
for C80H72O28: C, 64.86; H, 4.90; Found: C, 65.12; H, 4.83.
3. Experimental
3.1. Materials and apparatus
Melting points were obtained on a hot-plate microscope
1
apparatus and were uncorrected. H and 13C NMR spectra
were recorded with a Bruker AV-600 spectrophotometer. IR
spectra were obtained on a Nicolet FT-IR 740 spectrometer
(KBr disc). Elemental analysis was obtained on Perkin Elmer
1102b Instrument. X-ray data were collected on a Bruker
Smart APEX-2 diffractometer. Microwave heating is con-
ducted with Lingjiang LMMC-201 Microwave reactor
(Nanjing, China). Allreagents(pyrogallol, aromaticaldehydes,
benzyl chloride, n-butyl iodide, and ethyl a-chloroacetate)
and solvents (acetone, chloroform, dichloromethane,
3.2.4. Compound 4d. R¼p-Cl, 81.5%, mp>250 ꢃC; 1H
NMR (CDCl3, 600 MHz) d 7.08–7.19 (m, 16H, ArH), 6.21
(s, 2H, ArH), 5.90 (s, 2H, ArH), 5.43 (s, 4H, CH), 2.01–2.27
(m, 36H, COCH3); 13C NMR (CDCl3, 600 MHz) d 167.5,
166.7, 166.3, 140.7, 140.5, 136.6, 136.0, 133.0, 132.8, 130.4,
128.4, 126.5, 44.3, 20.2, 20.1, 20.0, 19.9; IR (KBr) n 2936
(w), 1780 (vs), 1485 (w), 1435 (m), 1365 (m), 1196 (vs),

C. Yan et al. / Tetrahedron 63 (2007) 9614–9620
9619
1168 (s), 1153 (s), 1027 (m), 721 (m) cmꢀ1. Anal. Calcd for
C76H60Cl4O24: C, 60.89; H, 4.04; Found: C, 60.67; H, 4.35.
600 MHz) d 149.3, 149.1, 146.2, 146.0, 139.4, 138.2,
137.9, 137.7, 137.5, 134.9, 133.9, 133.2, 128.7, 128.4,
128.3, 128.2, 128.1, 128.0, 127.8, 127.6, 127.3, 75.8, 75.0,
74.3, 74.1, 44.1, 21.0; IR (KBr) n 2924 (w), 2856 (w), 1635
(s), 1498 (m), 1383 (vs), 1311 (w) cmꢀ1. Anal. Calcd for
C140H120O12: C, 84.31; H, 6.06; Found: C, 84.56; H, 6.34.
3.2.5. Compound 4e. R¼o-OCOCH3, 88.9%, mp>250 ꢃC;
1H NMR (CDCl3, 600 MHz) d 6.76–7.02 (m, 12H, ArH),
6.46–6.50 (m, 4H, ArH), 6.12–6.20 (m, 2H, ArH), 5.76 (s,
2H, ArH), 5.54 (s, 4H, CH), 2.04–2.27 (m, 48H, COCH3);
13C NMR (CDCl3, 600 MHz) d 169.4, 169.3, 167.4, 167.3,
166.4, 148.6, 148.1, 140.7, 140.6, 136.2, 132.5, 131.9,
130.9, 130.5, 127.7, 126.0, 122.4, 121.6, 39.1, 20.6, 20.5,
20.1, 20.1, 19.9, 19.8; IR (KBr) n 2931 (w), 1783 (vs),
1635 (vs), 1481 (m), 1442 (s), 1376 (m), 1319 (m), 1207
(m), 1076 (m), 1040 (m), 870 (m) cmꢀ1. Anal. Calcd for
C84H72O32: C, 63.32; H, 4.55; Found: C, 63.54; H, 4.69.
3.3.3. Compound 5c. R¼p-OCH3, R0¼CH2Ph, 31.2%, mp
1
220–221 ꢃC; H NMR (CDCl3, 600 MHz) d 7.06–7.25 (m,
60H, ArH), 6.64 (s, 8H, ArH), 6.40 (s, 8H, ArH), 6.14 (s,
2H, CH), 6.01 (s, 4H, ArH), 5.61 (s, 2H, CH), 5.22 (s, 4H,
OCH2), 4.99 (s, 4H, OCH2), 4.66–4.78 (m, 12H, OCH2),
4.40 (m, 4H, OCH2), 3.50 (s, 12H, OCH3); 13C NMR
(CDCl3, 600 MHz) d 157.6, 149.2, 148.9, 138.2, 137.9,
137.7, 137.3, 134.5, 133.8, 133.5, 128.5, 128.2, 128.2,
128.1, 128.0, 127.9, 127.7, 127.6, 127.3, 76.0, 75.1, 74.2,
54.0, 43.8; IR (KBr) n 2924 (w), 2853 (w), 1635 (s), 1384
(vs), 1084 (w) cmꢀ1. Anal. Calcd for C140H120O16: C
81.69; H, 5.88; Found: C, 81.37; H, 5.59.
3.2.6. Compound 4f. R¼p-OCOCH3, 81.5%, mp>250 ꢃC;
1H NMR (CDCl3, 600 MHz) d 6.90 (d, J¼8.4 Hz, 9H,
ArH), 6.87 (d, J¼7.8 Hz, 3H, ArH), 7.79 (s, 3H, ArH), 7.71
(s, 4H, ArH), 6.25 (s, 1H, ArH), 6.19 (s, 1H, ArH), 6.02 (s,
2H, ArH), 5.48 (s, 4H, CH), 2.13–2.33 (m, 36H, COCH3),
1.96–2.00 (br, 2H, COCH3); 13C NMR (CDCl3, 600 MHz)
d 168.8, 168.7, 167.6, 167.4, 166.8, 166.7, 149.5, 140.8,
140.7, 140.4, 137.2, 136.5, 135.5, 133.2, 133.0, 132.3, 132.2,
130.1, 129.3, 129.2, 129.0, 128.2, 126.4, 125.3, 121.6, 121.3,
44.2, 21.3, 21.3, 20.1, 20.0, 19.9; IR (KBr) n 2931 (w), 1787
(vs), 1506 (m), 1477 (w), 1442 (m), 1372 (s), 1315 (w), 1196
(vs), 1076 (m), 1034 (s), 907 (w), 851 (w) cmꢀ1. Anal. Calcd
for C84H72O32: C, 63.32; H, 4.55; Found: C, 63.27; H, 4.71.
3.3.4. Compound 5d. R¼H, R0¼n-Bu, 45.3%, mp 149–
150 ꢃC; 1H NMR (CDCl3, 600 MHz) d 6.78 (s, 12H, ArH),
6.59 (s, 8H, ArH), 6.06 (s, 2H, CH), 5.83 (s, 4H, ArH),
5.37 (s, 2H, CH), 3.83–3.99 (m, 16H, OCH2), 3.16–3.32
(m, 8H, OCH2), 0.69–1.72 (m, 84H, CH2CH2CH3); 13C
NMR (CDCl3, 600 MHz) d 149.7, 149.6, 145.8, 145.4,
143.2, 132.9, 132.0, 129.0, 127.4, 126.7, 125.4, 123.8,
73.1, 73.0, 72.9, 72.7, 44.0, 32.7, 32.5, 32.5, 32.4, 19.5,
19.2, 19.1, 19.0, 14.2, 14.0, 13.9; IR (KBr) n 2959 (w),
2933 (w), 2873 (w), 1633 (m), 1463 (w), 1384 (vs), 1314
(w), 1093 (w) cmꢀ1. Anal. Calcd for C100H136O12: C,
78.49; H, 8.96; Found: C, 78.22; H, 8.85.
3.3. General procedure for alkylation of aryl pyrogal-
lol[4]arenes
To a 50 mL of flask were added aryl pyrogallol[4]arenes 3a
or 3b or 3c (1.0 mmol), potassium carbonate (12.0 mmol),
N,N-dimethylformamide (2.0 mL), polyethylene glycol
400 (2.0 mL), and alkyl halide (24.0 mmol). The mixture
was heated by microwave irradiation for about 3 min
(130 W). After cooling, the reaction mixture was poured
into 50 mL water and extracted with CHCl3. The organic
layer was dried with MgSO4. After evaporating the solvent
the residue was recrystallized with chloroform–ethanol to
give the white solid sample for analysis.
3.3.5. Compound 5e. R¼p-CH3, R0¼n-Bu, 41.5%, mp 118–
119 ꢃC; 1H NMR (CDCl3, 600 MHz) d 6.54–6.66 (m, 16H,
ArH), 6.09 (s, 2H, CH), 5.85 (s, 4H, ArH), 5.53 (s, 2H,
CH), 3.70–4.02 (m, 16H, OCH2), 3.24–3.40 (m, 8H,
OCH2), 2.18 (s, 12H, ArCH3), 0.82–1.78 (m, 84H,
CH2CH2CH3); 13C NMR (CDCl3, 600 MHz) d 149.6,
149.4, 145.4, 140.2, 134.2, 133.1, 132.1, 129.0, 127.9,
73.1, 72.7, 43.7, 32.7, 32.6, 32.5, 21.0, 19.5, 19.3, 19.1,
19.0, 14.2, 14.0, 13.9; IR (KBr) n 2939 (w), 2930 (w), 2871
(w), 1631 (m), 1515 (m), 1463 (w), 1436 (w), 1384 (vs),
1313 (w), 1090 (w) cmꢀ1. Anal. Calcd for C104H144O12: C,
78.75; H, 9.15; Found: C, 78.63; H, 8.97.
3.3.1. Compound 5a. R¼H, R0¼CH2Ph, 32.4%, mp 219–
220 ꢃC; 1H NMR (CDCl3, 600 MHz) d 7.06–7.25 (m, 60H,
ArH), 6.86 (m, 12H, ArH), 6.75 (s, 8H, ArH), 6.47 (s, 2H,
CH), 6.11 (s, 4H, ArH), 5.71 (s, 2H, CH), 5.29 (s, 2H,
OCH2), 5.27 (s, 2H, OCH2), 5.03 (s, 4H, OCH2), 4.70–
4.76 (m, 6H, OCH2), 4.60 (t, J¼9.6 Hz, 6H, OCH2), 4.34
(s, 2H, OCH3), 4.32 (s, 2H, OCH3); 13C NMR (CDCl3,
600 MHz) d 149.4, 149.1, 146.2, 145.9, 142.4, 138.1,
137.8, 133.7, 133.1, 128.8, 128.5, 128.2, 128.1, 128.0,
127.8, 127.5, 127.3, 75.8, 75.1, 74.3, 74.1, 65.1, 44.5,
15.31; IR (KBr) n 2924 (w), 2857 (w), 1633 (s), 1435 (m),
1383 (vs), 1315 (w) cmꢀ1. Anal. Calcd for C136H112O12:
C, 84.27; H, 5.82; Found: C, 84.03; H, 5.87.
3.3.6. Compound 5f. R¼p-OCH3, R0¼n-Bu, 47.3%, mp
1
128–129 ꢃC; H NMR (CDCl3, 600 MHz) d 6.42–6.57 (m,
16H, ArH), 6.08 (s, 2H, CH), 5.84 (s, 4H, ArH), 5.45
(s, 2H, CH), 3.91–4.02 (m, 12H, ArCH3), 3.71–3.78 (m,
16H, OCH2), 3.24–3.43 (m, 8H, OCH2), 0.84–1.79 (m,
84H, CH2CH2CH3); 13C NMR (CDCl3, 600 MHz) d 155.8,
148.1, 144.4, 144.0, 134.0, 131.7, 130.9, 128.5, 125.3,
122.2, 111.3, 71.7, 71.6, 71.5, 71.3, 53.4, 41.8, 31.3, 31.2,
31.1, 18.1, 17.8, 17.7, 17.6, 12.8, 12.6, 12.5; IR (KBr)
n 2954 (w), 2872 (w), 1635 (s), 1514 (w), 1436 (w), 1384
(vs), 1175 (w), 1084 (w) cmꢀ1
. Anal. Calcd for
C104H144O16: C, 75.69; H, 8.80; Found: C, 75.87; H, 9.14.
3.3.2. Compound 5b. R¼p-CH3, R0¼CH2Ph, 35.6%, mp
1
244–245 ꢃC; H NMR (CDCl3, 600 MHz) d 7.22–7.36 (m,
60H, ArH), 6.65–6.69 (m, 16H, ArH), 6.44 (s, 2H, CH),
6.08 (s, 4H, ArH), 5.82 (s, 2H, CH), 5.26 (s, 4H, OCH2),
5.02 (s, 4H, OCH2), 4.55–4.73 (m, 12H, OCH2), 4.34–4.35
(m, 4H, OCH2), 2.13 (s, 12H, ArCH3); 13C NMR (CDCl3,
3.3.7. Compound 5g. R¼H, R0¼CH2CO2Et, 27.9%, mp
1
118–119 ꢃC; H NMR (CDCl3, 600 MHz) d 6.97 (m, 12H,
ArH), 6.66 (s, 8H, ArH), 6.12 (s, 4H, ArH), 5.96 (s, 2H,
CH), 5.56 (s, 2H, CH), 4.28–4.71 (m, 24H, OCH2CO),

9620
C. Yan et al. / Tetrahedron 63 (2007) 9614–9620
5. (a) Atwood, J. L.; Barbour, L. J.; Jerga, A. Chem. Commun.
2001, 2376–2378; (b) McKinlay, R. M.; Thallapally, P. K.;
Atwood, J. L. Chem. Commun. 2006, 2956–2958.
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Atwood, J. L. Angew. Chem., Int. Ed. 2004, 43, 5263–5266.
7. Atwood, J. L.; Barbour, L. J.; Jerga, A. J. Supramol. Chem.
2001, 131–134.
4.02–4.15 (m, 24H, OCH2), 1.38 (t, J¼7.3 Hz, 6H, CH3),
1.19–1.24 (m, 30H, CH3); 13C NMR (CDCl3, 600 MHz)
d 169.1, 168.8, 168.7, 148.6, 148.5, 143.8, 142.7, 141.2,
133.3, 132.6, 128.8, 128.0, 127.1, 126.2, 123.8, 70.2, 69.9,
60.7, 60.7, 43.9, 14.2, 14.1, 14.0; IR (KBr) n 2935 (w),
1766 (vs), 1731 (s), 1604 (w), 1442 (s), 1379 (m), 1287
(m), 1210 (s), 1090 (s), 1055 (m), 703 (m) cmꢀ1. Anal. Calcd
for C100H112O36: C, 63.55; H, 5.97; Found: C, 63.82; H, 6.27.
8. Cometti, G.; Dalcanale, E.; Du Vosel, A.; Levelut, A. J. Chem.
Soc., Chem. Commun. 1990, 163–165.
3.3.8. Compound 5h. R¼p-CH3, R0¼CH2CO2Et, 20.8%,
9. Kobayashi, K.; Asakawa, Y.; Kato, Y.; Yasushi, A. J. Am.
Chem. Soc. 1992, 114, 10307–10313.
1
mp 150–151 ꢃC; H NMR (CDCl3, 600 MHz) d 6.81 (s,
10. (a) Avram, L.; Cohen, Y. J. Am. Chem. Soc. 2003, 125, 16180–
16181; (b) Avram, L.; Cohen, Y. J. Am. Chem. Soc. 2004, 126,
111556–111563.
11. Tanaka, Y.; Miyachi, M.; Kobuke, Y. Angew. Chem., Int. Ed.
1999, 38, 504–506.
8H, ArH), 6.54 (s, 8H, ArH), 6.07 (s, 4H, ArH), 5.96 (s,
2H, CH), 5.69 (s, 2H, CH), 4.27–4.67 (m, 24H, COOCH2),
4.08–4.16 (m, 24H, OCH2), 2.21 (s, 12H, ArCH3), 1.37 (t,
J¼7.2 Hz, 6H, CH3), 1.20–1.24 (br, 30H, CH3); 13C NMR
(CDCl3, 600 MHz) d 169.1, 168.9, 148.5, 148.5, 143.8,
142.8, 138.1, 135.3, 133.7, 132.7, 128.8, 128.6, 127.1,
123.8, 70.2, 69.9, 60.7, 43.5, 21.1, 14.3, 14.18; IR (KBr)
n 2937 (w), 1752 (vs), 1442 (s), 1280 (m), 1210 (s), 1083
(s) cmꢀ1. Anal. Calcd for C104H120O36: C, 64.19; H, 6.21;
Found: C, 64.45; H, 6.48.
€
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3.3.9. Compound 5i. R¼p-OCH3, R0¼CH2CO2Et, 25.3%,
15. Weinelt, F.; Schneider, H. J. J. Org. Chem. 1991, 56, 5527–
5535.
1
mp 178–179 ꢃC; H NMR (CDCl3, 600 MHz) d 6.35 (s,
16. Tunstad, L. M.; Tucker, J. A.; Dalcanale, E.; Weiser, J.; Bryant,
J. A.; Sherman, J. C.; Helgeson, R. C.; Knobler, C. B.; Cram,
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16H, ArH), 5.85 (s, 4H, ArH), 5.71 (s, 2H, CH), 5.36 (s,
2H, CH), 4.05–4.45 (m, 24H, COOCH2), 3.79–3.97 (m,
24H, OCH2), 3.53 (s, 12H, OCH3), 1.14 (t, J¼7.2 Hz, 6H,
CH3), 0.99–1.02 (br, 30H, CH3); 13C NMR (CDCl3,
600 MHz) d 169.1, 168.8, 157.9, 148.5, 148.7, 133.6,
133.3, 133.0, 129.7, 113.4, 70.3, 69.9, 60.8, 60.8, 60.7,
54.8, 43.1, 14.1, 14.0; IR (KBr) n 2931 (w), 1766 (vs),
1611 (m), 1583 (w), 1513 (s), 1470 (s), 1428 (s), 1386
(m), 1252 (s) cmꢀ1. Anal. Calcd for C104H120O40: C,
62.14; H, 6.02; Found: C, 62.39; H, 5.86.
€
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Acknowledgements
This work was financially supported by the National Natural
Science Foundation of China (Grant no. 20672091) and
Jiangsu Provincial Key Program of Physical Chemistry in
Yangzhou University, China. We are also grateful to Ms.
Min Shao for assistance in measuring the single crystal
structures.
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Supplementary data
Crystallographic data (CCDC-646541 for 4b, CCDC-
646542 for 4c, CCDC-646543 for 5a, CCDC-646544 for
5c, CCDC-646545 for 5d) have been deposited at the Cam-
bridge Crystallographic Database Centre. Supplementary
data associated with this article can be found in the online
version, at doi:10.1016/j.tet.2007.07.043.
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