Sonogashira coupling with aqueous ammonia directed to the synthesis of azotolane derivatives

Article abstract of DOI:10.1016/j.tet.2004.08.016

Sonogashira coupling with aqueous ammonia is tolerable for the reaction of aryl iodides or terminal alkynes bearing an azobenzene group. The reaction of (4-heptyloxyphenyl)ethyne with (4-heptyloxyphenyl)-(4-iodophenyl)diazene in the presence of 1 mol% of

Full text of DOI:10.1016/j.tet.2004.08.016

Tetrahedron 60 (2004) 9977–9982
Sonogashira coupling with aqueous ammonia directed to the
synthesis of azotolane derivatives
*
Mohamed S. Mohamed Ahmed and Atsunori Mori
Chemical Resources Laboratory, Tokyo Institute of Technology, R1-4 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
Received 29 June 2004; revised 6 August 2004; accepted 9 August 2004
Available online 11 September 2004
Abstract—Sonogashira coupling with aqueous ammonia is tolerable for the reaction of aryl iodides or terminal alkynes bearing an
azobenzene group. The reaction of (4-heptyloxyphenyl)ethyne with (4-heptyloxyphenyl)-(4-iodophenyl)diazene in the presence of 1 mol%
of PdCl2(PPh3)2, 2 mol% of CuI, and 2 equiv of 0.5 M aqueous ammonia gives the corresponding azotolane in 87% isolated yield after
stirring at room temperature for 15 h.
q 2004 Elsevier Ltd. All rights reserved.
1. Introduction
Herein, we report that the Sonogashira coupling with
aqueous ammonia takes place efficiently with several
substrates bearing an azobenzene group.
Organic holographic materials recently attract considerable
interest for storage and reconstruction of three-dimensional
image in the organic compound.1,2 Azotolanes,3 which
contain a carbon–carbon triple bond as well as an
azobenzene group, are potentially important component of
holographic materials since these compounds show liquid
crystalline and highly birefringent characteristics that
enable photo-induced order-disorder change to form holo-
graphic gratings of high diffraction efficiency.1a,4 Hence, the
synthetic methodology for azotolanes that is tolerable to
various functional groups would be the key for flexible and
efficient design of the target molecule.
2. Results and discussion
Prior to the coupling reaction to synthesize azotolanes, we
studied the Sonogashira coupling with a substrate bearing a
protic functional group such as NH2 or OH in aryl halide
with aqueous ammonia.7
The reaction of phenylethyne (1a) with 4-amino-1-iodo-
benzene (2a) was carried out in the presence of 1 mol% of
PdCl2(PPh3)2, 2 mol% of CuI and 2 equiv of 0.5 M aqueous
ammonia. The coupling product 3aa was obtained in 88%
isolated yield after stirring at room temperature for 2 h in
THF. On the other hand, no reaction was found to take place
in the absence of ammonia suggesting that the presence of
We have recently shown that the Sonogashira coupling
takes place with aqueous ammonia to afford a variety of
substituted alkynes highly efficiently.5,6 Our concern has
thus turned to apply the reaction for substrates bearing an
azobenzene moiety leading to azotolane derivatives.3
Scheme 1.
Keywords: Azotolane; Aqueous ammonia; Sonogashira; Palladium; Terminal alkynes.
* Corresponding author. Tel.: C81-459245231; fax: C81-459245224; e-mail: amori@res.titech.ac.jp
0040–4020/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2004.08.016

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M. S. Mohamed Ahmed, A. Mori / Tetrahedron 60 (2004) 9977–9982
Table 1. Cross coupling of terminal alkynes, R-C^CH, with aryl halides bearing a protic functional groupa
Alkyne (R)
Aryl halide
Time, h
3, %Yield
1a (Ph)
I–C6H4-2-NH2 (2b)
I–C6H4-2-OH (2c)
3.5
4
3ab, 87
3ac, 97
I–C6H4-4-OH (2d)
Br–C6H4-4-NH2 (2a0)
Br–C6H4-2-NH2 (2b0)
Br–C6H4-3-NH2 (2e0)
Br–C6H4-4-OH (2d0)
Br–C6H4-3-OH (2f0)
2
3ad, 96
3aa, 86b
3ab, 72b
3ae, 83b
3ad, 80b
3af, 77b
12
19
30
17
24
1b (Me3Si)
2a
2b
2c
2d
2
3.5
16
3
3ba, 86
3bb, 77
3bc, 63
3bd, 92
a
Unless noted, the reaction was carried out with 0.5 mmol aryl halide, 0.6 mmol alkyne, and 1 mL of 0.5 M aq NH3 in the presence of 1 mol% of PdCl2(PPh3)2,
2 mol% of CuI in THF at room temperature.
The reaction was performed at 60 8C with 3 mol% of PdCl2(PPh3)2 and 2 mol% of CuI. Instead of aq. NH3, 0.5 M of aq. 2-ethanolamine (2 equiv) was
employed.
b
the amino group in the aryl halide could not be a surrogate
promoter for ammonia as shown in Scheme 1.
trimethylsilylethyne (1b) and (4-cyanophenyl)ethyne (1d)
afforded the corresponding azotolanes 5ba and 5da in 87
and 79% yields, respectively. Worthy of note is that aryl
iodide 4b, which possesses a phenolic hydroxy group as
well as an azo group, also undergoes the coupling reaction.
Azotolanes bearing a hydroxy group 5bb, 5eb, and 5fb can
be converted into various ethers.10 Subsequently, introduc-
tion of an alkyl group of different chain length would be
applicable for the library of tail groups.
Table 1 summarizes the results of the cross-coupling
reaction of terminal alkynes with various aryl halides
bearing an amino or hydroxy group at room temperature in
the presence of 2 equiv of 0.5 M aqueous ammonia. The
reaction of 1a with 2-amino-1-iodobenzene (2b) similarly
proceeded to give 3ab in 87%. Use of aryl iodides bearing a
hydroxy group, 2-hydroxy-1-iodobenzene (2c)8 and
4-hydroxy-1-iodobenzene (2d) also resulted in giving the
coupling products 3ac and 3ad in 97 and 96% yields,
respectively. Aryl bromides bearing an amino (2a0, 2b0 and
2e0) or hydroxy group (2d0 and 2f0) effected the reaction,
which was carried out at 60 8C using an aqueous solution of
2-ethanolamine instead of ammonia.9 In addition, the
reaction of trimethylsilylethyne (1b) with several aryl
iodides took place to afford the coupling products in
excellent yields.
Scheme 3 represents that azotolanes can be synthesized with
different pathways. Treatment of 4a with 1g with the
palladium/copper catalyst system in the presence of aqueous
ammonia afforded azotolane 5ga in 87% yield after stirring
at room temperature for 14 h. On the other hand, azo alkyne
1h and aryl iodide 2h also effected the reaction to furnish the
identical product with that of the former reaction in 79%
yield. These results show that the reaction with aqueous
ammonia proceeds by employing terminal alkynes bearing
an azo group as well as aryl halides.
Studies on the reaction bearing an amino group on the
aromatic group of aryl alkynes were then carried out. As
summarized in Scheme 2, the reaction of (4-aminopheny-
l)ethyne (1c) with 4-methoxy-1-iodobenzene (2g) was
found to proceed to give 3cg in 74% yield after stirring at
room temperature for 4 h. The coupling reaction of terminal
alkyne 1c and aryl halide 2a, both of which possessed an
amino group on the aromatic group, proceeded to afford
3ca.
It is also remarkable that sila-Sonogashira coupling,11
which is the reaction of trimethylsilylalkyne with aryl
triflate was found to take place. The reaction of 5ba with
4-cyanobenzene triflate afforded 5da in 81% yield with the
Pd(0)/CuCl catalyst system in DMF at 80 8C (Scheme 4).
3. Conclusion
The Sonogashira coupling with aqueous ammonia was
applied for the reaction of aryl alkynes 1 and aryl iodide
bearing an azo group 4. As summarized in Table 2, the
reaction was found to take place smoothly. With 4a bearing
an n-heptyloxy group the coupling reaction of
Coupling reactions of alkynes with aryl halides, in which an
azo group is incorporated in the molecule, produce
azotolanes in good to excellent yields. The reaction was
also found to be applicable for substrates bearing a protic
functional group such as NH2 or OH on the aromatic ring.
Scheme 2.

M. S. Mohamed Ahmed, A. Mori / Tetrahedron 60 (2004) 9977–9982
Table 2. Sonogashira coupling of aryl iodide bearing an azo group 4 with aqueous ammoniaa
9979
Alkyne (R)
Iodide (X)
Time, h
5, %yield
1b (Me3Si)
1d (4-NC–C6H4)
1b
4a (nC7H15
4a
4b (H)
4b
4b
)
5
16
3
18
24
5ba, 87
5da, 79
5bb, 90
5eb, 76
5fb, 77
1e (t-Bu)
1f (nC6H13
)
a
The reaction was carried out with 0.5 mmol aryl halide, 0.6 mmol alkyne, and 1 mL of 0.5 M aq. NH3 in the presence of 1 mol% of PdCl2(PPh3)2, 2 mol%
of CuI in THF at room temperature.
Scheme 3.
Scheme 4.
Since isolation and purification procedures for the reaction
with aqueous ammonia are quite simple compared with
those of conventional Sonogashira conditions, the reaction
provides a practical azotolane synthesis that enables to
design derivatives bearing a wide range of functional groups
and alkyl groups with different chain length directed toward
holographic materials of high performance.
4. Experimental
4.1. General
All reactions were performed under an atmosphere of argon
using standard Schelnk tubes. Melting points were recorded
using an Electrothermal melting point apparatus. Infrared

9980
M. S. Mohamed Ahmed, A. Mori / Tetrahedron 60 (2004) 9977–9982
spectra were recorded on Shimadzu FT/IR-8100 spec-
2H), 6.63 (d, JZ8.1 Hz, 2H), 6.86 (d, JZ8.7 Hz, 2H), 7.32
(d, JZ8.1 Hz, 2H), 7.43 (d, JZ8.7 Hz, 2H). 13C NMR
(CDCl3) 55.24, 87.11, 88.59, 112.96, 113.90, 114.75,
116.02, 132.74 (br), 146.36, 159.17. HRMS (EI) m/z
Calcd for C15H13NO 223.0997, found 223.0978.
1
trometer and presented in cmK1. H and 13C NMR spectra
were recorded on a Varian Mercury 300 NMR spectrometer
1
in CDCl3. The H (300 MHz) and 13C (75 MHz) chemical
shifts were referenced to residual CHCl3 (d 7.26 ppm) for
1H and (77.0 ppm) for 13C. High resolution mass spectra
(HRMS) were recorded using JEOL JMS-700 (70 eV).
Elemental analyses were carried out at the Elemental
Analysis Center of Tokyo Institute of Technology using a
Yanaco MT-5 CHN auto recorder and SX-Elements Micro
Analyzer.
The following coupling product was obtained in a manner
described above: bis-(4-aminophenyl)ethyne (3ca).21
4.4. (4-Heptyloxyphenyl)-(4-iodophenyl)diazene (4a)
To a solution of KOH (2.94 mmol) and 4-iodoazophenol
(1.47 mmol) in 4 mL DMSO was added 1-iodoheptane
(2.2 mmol). The resulting mixture was then stirred for 2.5 h
at room temperature. After the reaction was complete, the
resulting mixture was extracted with chloroform (3!
15 mL) and the combined organic layer was dried over
anhydrous MgSO4, and concentrated in vacuo. The residue
was purified by flash chromatography using (10:1 hexanes–
ethyl acetate) to afford 551 mg of 4a (93%) as an orange
solid. Mp 112–113 8C. IR (KBr) 2953, 2857, 1605.0, 1584,
4.2. General method for the cross coupling of terminal
alkynes with aryl halides bearing a protic functional
group
To PdCl2(PPh3)2 (3.5 mg, 0.005 mmol), CuI (1.9 mg,
0.01 mmol), and 2 (0.5 mmol) in 3 mL of THF was added
1 (0.6 mmol) at room temperature. A 0.5 M solution of
aqueous ammonia (2 mL, 1 mmol) was then added dropwise
and stirring was continued for the period given in Table 1 at
room temperature. Two phases of the resulting mixture were
separated and the aqueous layer was extracted with diethyl
ether. The combined organic layer was concentrated under
reduced pressure to leave a crude solid, which was purified
by chromatography on silica gel (hexanes–ethyl acetate) to
furnish the corresponding coupling product in good to
excellent yields.
1
1559 cmK1. H NMR (CDCl3) d 0.90 (t, JZ6.9 Hz, 3H),
1.31–1.50 (m, 8H), 1.79–1.85 (m, 2H), 4.04 (t, JZ6.6 Hz,
2H), 7.00 (d, JZ9.0 Hz, 2H), 7.61 (d, JZ9.0 Hz, 2H), 7.84
(d, JZ9.0 Hz, 2H), 7.90 (d, JZ9.0 Hz, 2H). 13C NMR
(CDCl3) 14.09, 22.60, 25.95, 29.04, 29.16, 31.75, 68.38,
96.60, 114.75, 124.20, 124.96, 138.22, 146.60, 152.03,
162.05. HRMS (EI) m/z Calcd for C14H13IN2O 422.0855,
found 422.0846.
4.2.1. 4-(Phenylethynyl)aniline (3aa).12 Purified by
chromatography on silica gel (30:1 hexanes–ethyl acetate)
afforded 3aa in 88% yield (85 mg, 0.44 mmol).
4.5. General procedure for Sonogashira coupling of aryl
iodide bearing an azobenzene moiety with aqueous
ammonia
The following coupling products were obtained in a manner
described above: 2-(phenylethynyl)aniline (3ab),13
2-(phenylethynyl)phenol (3ac),14 4-(phenylethynyl)phenol
(3ad),15 3-(phenylethynyl)aniline (3ae),7b 3-(phenylethynyl)-
phenol (3af),16 4-(trimethylsilylethynyl)aniline (3ba),17
2-(trimethylsilylethynyl)aniline (3bb),18 2-(trimethylsilyl-
ethynyl)phenol (3bc),19 4-(trimethylsilylethynyl)phenol
(3bd).20
To PdCl2(PPh3)2 (3.5 mg, 0.005 mmol), CuI (1.9 mg,
0.01 mmol), and 4 (0.5 mmol) in 3 mL of THF was added
1 (0.6 mmol) at room temperature. A 0.5 M solution of
aqueous ammonia (2 mL, 1 mmol) was then added dropwise
and stirring was continued for the period given in Table 2 at
room temperature. Two phases of the resulting mixture were
separated and the aqueous layer was extracted with diethyl
ether. The combined organic layer was concentrated under
reduced pressure to leave a crude solid, which was purified
by chromatography on silica gel (hexanes–ethyl acetate) to
furnish the corresponding coupling product in good to
excellent yield.
4.3. General procedure for Sonogashira-coupling
reaction of 4-aminophenylethyne with aryl iodides
To PdCl2(PPh3)2 (3.5 mg, 0.005 mmol), CuI (1.9 mg,
0.01 mmol), and 2 (0.5 mmol) in 3 mL of THF was added
4-aminophenylethyne (1c) (63.5 mg, 0.5 mmol) at room
temperature under an argon atmosphere. A 0.5 M solution of
aqueous ammonia (2 mL, 1 mmol) was then added dropwise
and stirring was continued for the period given in Scheme 2 at
room temperature. Two phases of the resulting mixture were
separated and the aqueous layer was extracted with diethyl
ether. The combined organic layer was concentrated under
reduced pressure to leave a crude solid, which was purified by
chromatography on silica gel (hexanes–ethyl acetate) to
furnish the corresponding coupling product in good yield.
4.5.1. (4-Heptyloxyphenyl)-{(4-trimethylsilylethynyl)-
phenyl}diazene (5ba). Purified by chromatography on
silica gel (20:1 hexanes–ethyl acetate) to furnish 170.8 mg
of 5ba (87%) as an orange solid. Mp 93–94 8C. IR (KBr)
2955, 2938, 2924, 2867, 2161, 1605, 1584 cmK1. 1H NMR
(CDCl3) d 0.27 (s, 9H), 0.90 (t, JZ6.6 Hz, 3H), 1.32–1.51
(m, 8H), 1.79–1.86 (m, 2H), 4.04 (t, JZ6.6 Hz, 2H), 7.00
(d, JZ9.0 Hz, 2H), 7.58 (d, JZ9.0 Hz, 2H), 7.81 (d, JZ
9.0 Hz, 2H), 7.90 (d, JZ9.0 Hz, 2H). 13C NMR (CDCl3)
K0.08, 14.07, 22.59, 25.95, 29.03, 29.16, 31.75, 68.32,
96.49, 104.83, 114.69, 122.45, 124.89, 132.33, 132.72,
146.82, 152.07, 161.95. HRMS (EI) m/z Calcd for
C24H32N2OSi 392.2284, found 392.2280.
4.3.1. 4-(4-Methoxyphenylethynyl)aniline (3cg). Purified
by flash chromatography on silica gel (50:1 hexanes–ethyl
acetate) to afford 83 mg of 3cg (74%) as a white solid. Mp
140–141 8C. IR (KBr) 3447, 3359, 3034, 3011, 2211,
1607 cmK1. 1H NMR (CDCl3) d 3.82 (s, 3H), 3.80–3.83 (br,
4.5.2. 4-[4-(4-Heptyloxyphenylazo)phenylethynyl]benzo-
nitrile (5da). Purified by chromatography on silica gel (5:1

M. S. Mohamed Ahmed, A. Mori / Tetrahedron 60 (2004) 9977–9982
9981
hexanes–ethyl acetate) to furnish 110 mg of 5da (79%) as
an orange solid. Mp 171–172 8C. IR (KBr) 2940, 2872,
123.83, 124.94, 132.90, 146.80, 152.36, 162.02. HRMS (EI)
m/z Calcd for C21H24N2O 320.1889, found 320.1892.
1
2855, 2226, 2213, 1601, 1580 cmK1. H NMR (CDCl3) d
0.90 (t, JZ7.2 Hz, 3H), 1.34–1.51 (m, 8H), 1.79–1.86 (m,
2H), 4.05 (t, JZ6.6 Hz, 2H), 7.01 (d, JZ9.0 Hz, 2H), 7.62–
7.68 (m, 6H), 7.90 (d, JZ8.4 Hz, 2H), 7.93 (d, JZ9.0 Hz,
2H). 13C NMR (CDCl3) 14.06, 22.58, 25.94, 29.01, 29.14,
31.74, 68.39, 89.58, 93.59, 111.65, 114.76, 118.45, 122.69,
123.86, 125.00, 127.97, 132.05, 132.08, 132.60, 146.81,
152.48, 162.14. HRMS (EI) m/z Calcd for C28H27N3O
421.2154, found 421.2142.
4.5.7. (4-Heptyloxyphenyl)-[4-(4-heptyloxyphenylethy-
nyl)phenyl]diazene (5ga). Purified by chromatography on
silica gel (20:1 hexanes–ethyl acetate) to furnish 110 mg of
5ga (86%) as an orange solid. Mp 173–174 8C. IR (KBr)
2953, 2936, 2924, 2872, 2861, 2215, 1603, 1584 cmK1. 1H
NMR (CDCl3) d 0.90 (t, JZ6.6 Hz, 6H), 1.25–1.51 (m,
16H), 1.74–1.87 (m, 4H), 3.98 (t, JZ6.6 Hz, 2H), 4.04 (t,
JZ6.6 Hz, 2H), 6.88 (d, JZ9.0 Hz, 2H), 7.0 (d, JZ9.0 Hz,
2H), 7.48 (d, JZ8.4 Hz, 2H), 7.62 (d, JZ8.4 Hz, 2H), 7.86
(d, JZ9.0 Hz, 2H), 7.91 (d, JZ9.0 Hz, 2H). 13C NMR
(CDCl3) 14.06, 22.60, 25.98, 29.04, 29.20, 31.77, 68.13,
68.41, 88.07, 91.84, 114.62, 114.76, 114.90, 122.61, 124.84,
125.67, 132.15, 133.13, 146.96, 151.79, 159.47, 161.91.
Anal. Calcd for C34H42N2O2: C, 79.96; H, 8.29; N, 5.49.
Found: C, 79.56; H, 8.23; N, 5.38.
4.5.3. 4-[(4-Trimethylsilylethynyl)phenylazo]phenol
(5bb). Purified by chromatography on silica gel (10:1
hexanes–ethyl acetate) to furnish 132.4 mg of 5bb (90%) as
an orange solid. Mp 129–130 8C. IR (KBr) 3170 (br), 2957,
1
2155, 1603, 1593 cmK1. H NMR (CDCl3) d 0.27 (s, 9H),
5.27 (brs, 1H), 6.96 (d, JZ9.0 Hz, 2H), 7.59 (d, JZ8.1 Hz,
2H), 7.82 (d, JZ8.1 Hz, 2H), 7.89 (d, JZ9.0 Hz, 2H). 13C
NMR (CDCl3) K0.10, 96.77, 104.77, 115.90, 122.48,
125.16, 132.78, 147.09, 151.91, 158.57. HRMS (EI) m/z
Calcd for C17H18N2OSi 294.1188, found 294.1194.
4.6. Coupling of 5ba with 4-cyanobenzene triflate
To 25 mL Schlenk tube under argon atmosphere were added
PdCl2(PPh3)2 (17.5 mg, 0.025 mmol), CuCl (4.95 mg,
0.05 mmol), 4-cyanobenzene triflate (125.6 mg,
0.5 mmol), and 5ba (196.3 mg, 0.5 mmol) in 3 mL of
DMF at room temperature. The stirring was continued for
24 h in an oil bath at 80 8C. The resulting mixture was then
cooled down and followed the general aqueous workup.
The crude product was then purified by chromatography on
silica gel (hexanes–ethyl acetate) to furnish 113 mg of 5da
(81%).
4.5.4. 4-[4-(3,3-Dimethylbut-1-ynyl)phenylazo]phenol
(5eb). Purified by chromatography on silica gel (10:1
hexanes–ethyl acetate) to furnish 107 mg of 5eb (76%) as an
orange solid. Mp 154–155 8C. IR (KBr) 3235 (br), 2967,
2929, 2865, 2234, 1593 cmK1. 1H NMR (CDCl3) d 1.34 (s,
9H), 5.18 (brs, 1H), 6.94 (d, JZ9.0 Hz, 2H), 7.50 (d, JZ
8.7 Hz, 2H), 7.80 (d, JZ8.7 Hz, 2H), 7.87 (d, JZ9.0 Hz,
2H). 13C NMR (CDCl3) 28.08, 30.94, 79.05, 101.15,
115.91, 122.45, 125.02, 126.37, 132.32, 147.04, 151.32,
158.54. HRMS (EI) m/z Calcd for C18H18N2O 278.1419,
found 278.1411.
Acknowledgements
4.5.5. 4-(4-Oct-1-ynylphenylazo)phenol (5fb). Purified by
chromatography on silica gel (10:1 hexanes–ethyl acetate)
to furnish 118 mg of 5fb (77%) as an orange solid. Mp 103–
104 8C. IR (KBr) 3320 (br), 2957, 2930, 2857, 2226,
We thank Professor Tomiki Ikeda of Tokyo Institute of
Technology for fruitful discussion on holography with
azotolanes. M. S. M. A. thanks Ministry of Education,
Sports, Culture, Science, and Technology, Japan for
fellowship for the doctoral program.
1
1595 cmK1. H NMR (CDCl3) d 0.92 (t, JZ6.6 Hz, 3H),
1.31–1.66 (m, 8H), 2.44 (t, JZ7.2 Hz, 2H), 5.38 (brs, 1H),
6.94 (d, JZ8.7 Hz, 2H), 7.51 (d, JZ8.7 Hz, 2H), 7.81 (d,
JZ8.7 Hz, 2H), 7.88 (d, JZ8.7 Hz, 2H). 13C NMR (CDCl3)
14.03, 19.54, 22.52, 28.61 (br), 31.32, 80.55, 93.25, 115.91,
122.48, 125.04, 126.40, 132.31, 147.02, 151.33, 158.54.
HRMS (EI) m/z Calcd for C20H22N2O 306.1732, found
306.1729.
References and notes
1. (a) Ikeda, T. J. Mater. Chem. 2003, 13, 2037–2057. (b) Berg,
R. H.; Hvilsted, S.; Ramanujam, P. S. Nature 1996, 383,
505–508. (c) Rasmussen, P. H.; Ramanujam, P. S.; Hvilsted,
S.; Berg, R. H. J. Am. Chem. Soc. 1999, 121, 4738–4743.
(d) Eich, M.; Wendorff, J. H. Makromol. Chem., Rapid
Commun. 1987, 8, 59–63.
4.5.6. (4-Heptyloxyphenylazo)-phenylethyne (1h). To a
solution of 5bb (196 mg, 0.5 mmol) in 3 mL methanol was
added K2CO3 (26.6 mg, 0.19 mmol). The stirring was
continued at room temperature for 40 min. The solvent
was then evaporated under reduce pressure and the resulted
crude sample subjected to aqueous workup and purified
through flash chromatography (hexanes–ethyl acetat 10:1)
afforded 134.5 mg of 1 h (84%) as a red solid. Mp 89 8C. IR
(KBr) 3285, 2961, 2936, 2924, 2872, 2859, 1603,
2. (a) Yamamoto, T.; Hasegawa, M.; Kanazawa, A.; Shiono, T.;
Ikeda, T. J. Phys. Chem. B 1999, 103, 9873–9878.
(b) Hasegawa, M.; Yamamoto, T.; Kanazawa, A.; Shiono,
T.; Ikeda, T. Adv. Mater. 1999, 11, 675–677. (c) Yamamoto,
T.; Yoneyama, S.; Tsutsumi, O.; Kanazawa, A.; Shiono, T.;
Ikeda, T. J. Appl. Phys. 2000, 88, 2215–2220. (d) Yamamoto,
T.; Ohashi, A.; Yoneyama, S.; Hasegawa, M.; Tsutsumi, O.;
Kanazawa, A.; Shiono, T.; Ikeda, T. J. Phys. Chem. B 2001,
105, 2308–2313. (e) Yoneyama, S.; Yamamoto, T.; Tsutsumi,
O.; Kanazawa, A.; Shiono, T.; Ikeda, T. Macromolecules
2002, 35, 8751–8758.
1
1586 cmK1. H NMR (CDCl3): d 0.90 (t, JZ6.9 Hz, 3H),
1.32–1.48 (m, 8H), 1.83 (quent, JZ8.4 Hz, 2H), 3.21 (s,
1H), 4.05 (t, JZ6.6 Hz, 2H), 7.00 (d, JZ9.0 Hz, 2H), 7.61
(d, JZ8.4 Hz, 2H), 7.84 (d, JZ8.4 Hz, 2H), 7.91 (d, JZ
9.0 Hz, 2H). 13C NMR (CDCl3) 14.06, 22.59, 25.95, 29.03,
29.16, 31.75, 68.37, 79.04, 82.96, 114.72, 122.49, 122.61,

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M. S. Mohamed Ahmed, A. Mori / Tetrahedron 60 (2004) 9977–9982
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