Synthesis and spectral properties of novel fluorescent diethoxycarbonyl glycoluril derivatives

Article abstract of DOI:10.1055/s-2007-986671

A novel class of fluorescent diethoxycarbonyl glycoluril derivatives with aryl alkyne side chains was synthesized via alkylation and subsequent Sonogashira cross-coupling reactions. The fluorescence spectra showed that these compounds exhibited good blue fluorescence with the maximum wavelengths ranging from 368 nm to 403 nm. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2007-986671

LETTER
2533
Synthesis and Spectral Properties of Novel Fluorescent Diethoxycarbonyl
Glycoluril Derivatives
S
ynthesis and Spec
e
tral
P
roper
n
ties of
D
ietho
g
xycarbonyl
f
G
lycolu
a
ril
D
erivativ
n
es g She, Meng Gao, Liping Cao, Guodong Yin, Anxin Wu*
Key Laboratory of Pesticide and Chemical Biology, Ministry of Education, Central China Normal University,
Wuhan 430079, P. R. of China
E-mail: chwuax@mail.ccnu.edu.cn
Received 19 June 2007
two ureidyl N–H that can act as the binding sites. We
believe that complexation will take place between these
fluorescent derivatives containing two ureidyl N–H
groups and the corresponding anion through hydrogen-
Abstract: A novel class of fluorescent diethoxycarbonyl glycoluril
derivatives with aryl alkyne side chains was synthesized via alkyla-
tion and subsequent Sonogashira cross-coupling reactions. The
fluorescence spectra showed that these compounds exhibited good
blue fluorescence with the maximum wavelengths ranging from bonding interactions.
368 nm to 403 nm.
The synthetic route used to obtain fluorescent derivatives
Key words: diethoxycarbonyl glycoluril, aryl alkyne, Sonogashira
5a–h is shown in Scheme 1. Most glycolurils have poor
solubility in common organic solvents. In order to solve
the solubility problem, the more organic soluble diethoxy-
carbonyl glycoluril 3 was synthesized according to the
literature procedure15 and used for these studies. Com-
pound 3 was alkylated with 1,2-bis(bromomethyl)-4,5-di-
bromobenzene using t-BuOK as base in anhydrous
DMSO to give 4 in 59% yield. The coupling reaction
between 4 and a number of terminal alkynes was readily
accomplished using Pd(PPh3Cl2)2 and CuI as catalysts in
the presence of Et3N in DMF at 100 °C, and the expected
compounds 5a–h, a novel class of fluorescent diethoxy-
carbonyl glycoluril derivatives, were obtained.
cross-coupling, fluorescence
The development of fluorescent sensors capable of selec-
tively detecting chemical species including cations1 and
anions2 has always been of particular interest due to high
sensitivity and selectivity,3 ‘on–off’ switchability and
hence their use as logic gates,4 and convenient monitoring
of molecular-level events through light signals. A fluores-
cent sensor typically consists of three components, which
are a recognition part that binds the target analyte, a read-
out part that signals binding, and a linker that connects the
recognition part and the readout part. In the case of anion
sensors, hydrogen-bonding groups have been widely used
in binding sites for anion recognition. Hydrogen-bonding
sites typically used in fluorogenic chemosensors are
ureas,5 thioureas,6 calyx[4]pyrroles,7 sapphyrins,8 por-
phyrins,9 and amides.10
O
HN NH
O
HO
O
O
COOEt
COOEt
OH
OH
(i)
(iii)
EtOOC
COOEt
HO
(ii)
HN
NH
O
O
Glycolurils, due to their special precaved structure, were
widely used as platforms or building blocks to construct a
series of compounds with more sophisticated structures in
the past decades.11 On the other hand, glycoluril deriva-
tives have been used in a variety of applications including
polymer cross-linking, psychotropic agents, explosives,
in the stabilization of organic compounds against photo-
degradation, textile waste stream purification, and combi-
natorial chemistry.12 However, one area of glycoluril
derivatives that has been less well explored is their utili-
zation as fluorescent chemosensors for anions.13
1
2
3
O
O
O
R1
HN
HN
N
Br
Br
HN
N
R
N
(iv)
(v)
R
R
R
N
HN
R1
O
R = COOEt
R = COOEt
4
5
Scheme 1 Reagents and conditions: (i) AcOH, Br2, H2O; (ii) EtOH,
HCl (g), 0 °C; (iii) PhH, H2NCONH2, TFA, reflux; (iv) 1,2-bis(bro-
momethyl)-4,5-dibromobenzene, t-BuOK, DMSO; (v) R1C≡CH,
Pd(PPh3)2Cl2, CuI, Et3N, DMF.
One of our research interests is to develop a new genera-
tion of potential fluorescent anion sensors based on the
diethoxycarbonyl glycoluril. We used Sonogashira
coupling14 to attach terminal aryl alkynes covalently to
aromatic sidewalls of glycoluril derivative 4 and build p-
systems that can be used as the signaling subunit and used
A variety of substrates were used in this reaction
(Table 1). Taking into consideration that the nature of the
substituents in phenylacetylene could affect the fluores-
cence intensity and emission wavelength, we have synthe-
sized five different para-substituted phenylacetylenes,16
4-ethynylpyridine17 and 3-ethynylpyridine.17 The experi-
mental results showed that the yields were not affected
drastically in the presence of either electron-donating or
SYNLETT 2007, No. 16, pp 2533–2536
0
1
.1
0
.2
0
0
7
Advanced online publication: 12.09.2007
DOI: 10.1055/s-2007-986671; Art ID: W11507ST
© Georg Thieme Verlag Stuttgart · New York

2534
N. She et al.
LETTER
electron-withdrawing groups on phenylacetylene. All re-
action products gave satisfactory 1H NMR, 13C NMR, MS
and IR data.18 In addition, the structure and conformation
of compound 5a, was further elucidated by single-crystal
X-ray diffraction,19 as shown in Figure 1. The compound
has a well-defined geometry due to the rigidity that the
fused rings confer on the molecule. The angle between the
mean planes defined by the five-membered rings is
116.9°. The distance between two carbonyl oxygen atoms
(O1–O2) of the glycoluril moiety is 5.70 Å. Interestingly,
one of the ethynyl is tortuose with a torsion angle of
170.1°. The phenyl ring C (C1–C6) of the sidewall and
phenyl ring D (C9–C14) of the side chain are essentially
coplanar with a dihedral angle of 3.7°. The phenyl ring C
(C1–C6) is twisted with respect to ring E (C17–C22)
making a dihedral angle of 13.5°.
Table 1 Synthesis of Fluorescent Derivatives 5a–h from Terminal
Aryl Alkynes
R1
Entry
1
Product Yield (%)a
5a
5b
75
70
Figure 1 X-ray crystal structure of compound 5a; hydrogen atoms
and solvent molecules are omitted for clarity
2
Table 2 Absorption and Fluorescence Data of 5a–h
3
4
5
6
5c
5d
5e
5f
78
80
69
65
Compound labsmax (nm)a
lemmax (nm)a
370
Relative fluorescence
OH
5a
5b
5c
5d
5e
5f
278
316
292
292
275
275
290
300
2.4
4.6
4.2
4.7
1.4
1.0
2.6
6.6
OMe
402
394
N
392
368
N
370
7
5g
5h
73
70
CONH2
5g
5h
385
8
403
NHCOMe
a Measured in acetonitrile.
a Isolated yield.
Similarly, red shifts of 5c, 5d and 5h with respect to 5a
were presumably attributed to the more electron-donating
nature of the substituent groups.
The photophysical properties of compounds 5a–h were
examined in dilute acetonitrile solution (10–5 M) and are
summarized in Table 2. The emission spectra of 5a–h in
acetonitrile solution (1 × 10–5 M) are presented in
Figure 2. It was found that 5a, 5e and 5f exhibited a simi-
lar lmax of emission (368–370 nm). Fluorescence maxi-
mum wavelengths of other derivatives differed from each
other. Compared to 5a with an emission maximum at 370
nm, the emission spectrum of 5b exhibited a 32 nm batho-
chromic shift due to the larger p-conjugation of the naph-
thyl group as compared to that of the phenyl groups of 5a.
In summary, we have synthesized a novel class of fluores-
cent diethoxycarbonyl glycoluril derivatives with aryl
alkyne side chains via alkylation and subsequent Sono-
gashira cross-coupling reactions. Moreover, their absorp-
tion and fluorescence in acetonitrile solution were studied.
They exhibited different emitting fluorescence wave-
lengths ranging from 368 nm to 403 nm. Further studies
on the chemosensor behavior of the new generation of
fluorescent derivatives toward various anions are under-
way in our laboratory.
Synlett 2007, No. 16, 2533–2536 © Thieme Stuttgart · New York

LETTER
Synthesis and Spectral Properties of Diethoxycarbonyl Glycoluril Derivatives
2535
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1961.
Figure 2 The fluorescence emission spectra of 5a–h in acetonitrile
solution (1 × 10–5 M)
(16) (a) Takahashi, S.; Kuroyama, Y.; Sonogashira, K.; Hagihara,
N. Synthesis 1980, 627. (b) Yashima, E.; Huang, S.;
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Acknowledgment
This work was supported by Central China Normal University, the
National Natural Science Foundation of China (Grant No.20472022
and No. 20672042), and the Scientific Research Foundation for the
Returned Overseas Chinese Scholars, State Education Ministry
(No. [2005]383).
(17) Ciana, L. D.; Haim, A. J. Heterocycl. Chem. 1984, 21, 607.
(18) General Procedure for the Synthesis of Compounds 5: To
a solution of Pd(PPh3)2Cl2 (36 mg, 0.05 mmol), CuI (19 mg,
0.10 mmol) and compound 4 (273 mg, 0.50 mmol) in freshly
distilled Et3N (15 mL) and DMF (25 mL) under Ar
atmosphere at r.t., were added phenylethynylene (204 mg,
2 mmol). The mixture was warmed to 100 °C for 14 h
(monitored by TLC), and then the solvent was removed
under reduced pressure. The solid residue was purified by
flash chromatography (SiO2, CH2Cl2–MeOH, 50:1) to give
5a (221 mg, 0.375 mmol, 75%) as a white solid. Compound
5a: IR (KBr): 3405 (w), 3213 (w), 3066 (w), 2981 (w), 1758
(s), 1724 (s), 1709 (s), 1468 (m), 1282 (s), 1091 (m), 1032
(m), 758 (s), 689 (m) cm–1. 1H NMR (400 MHz, CDCl3): d =
7.34–7.56 (m, 12 H), 5.99 (s, 2 H), 4.85 (d, J = 16.0 Hz, 2
H), 4.43 (d, J = 16.0 Hz, 2 H), 4.33 (q, J = 6.8 Hz, 2 H), 4.26
(q, J = 6.8 Hz, 2 H), 1.34 (t, J = 6.8 Hz, 3 H), 1.31 (t, J = 6.8
Hz, 3 H). 13C NMR (100 MHz, CDCl3): d = 165.77, 165.46,
156.89, 135.97, 132.75, 131.70, 128.55, 128.36, 125.66,
123.00, 94.95, 87.53, 82.88, 73.47, 63.72, 63.40, 44.29,
13.98, 13.82. ESI–MS: m/z = 588.9 [M + H]+, 611.0 [M +
Na]+. Compound 5b: IR (KBr): 3418 (w), 3059 (w), 2981
(w), 2822 (w), 1759 (s), 1733 (s), 1702 (s), 1466 (s), 1426
(m), 1274 (m), 1136 (w), 804 (w), 774 (s) cm–1. 1H NMR
(400 MHz, DMSO-d6): d = 8.61 (s, 2 H), 8.40 (d, J = 8.4 Hz,
2 H), 8.05 (d, J = 8.4 Hz, 2 H), 7.99 (d, J = 8.4 Hz, 2 H), 7.88
(d, J = 7.2 Hz, 2 H), 7.81 (s, 2 H), 7.57 (q, J = 8.0 Hz, 2 H),
7.50 (d, J = 7.2 Hz, 2 H), 7.12 (q, J = 8.0 Hz, 2 H), 4.79 (d,
J = 16.0 Hz, 2 H), 4.58 (d, J = 16.0 Hz, 2 H), 4.28 (q, J = 7.2
Hz, 2 H), 4.17 (q, J = 7.2 Hz, 2 H), 1.28 (t, J = 7.2 Hz, 3 H),
1.23 (t, J = 7.2 Hz, 3 H). 13C NMR (100 MHz, DMSO-d6):
d = 166.45, 166.00, 157.10, 138.50, 132.89, 132.82, 132.43,
131.01, 129.66, 128.53, 127.19, 126.77, 125.65, 125.52,
123.73, 119.39, 92.46, 91.85, 82.37, 74.19, 62.96, 62.72,
43.37, 13.84, 13.78. ESI–MS: m/z = 689.1 [M + H]+, 711.1
[M + Na]+. Compound 5c: IR (KBr): 3363 (s), 3261 (s), 3039
(w), 2984 (w), 2209 (w), 1769 (s), 1710 (s), 1691 (s), 1605
(s), 1514 (s), 1481 (s), 1267 (s), 1226 (m), 1144 (w), 1038
(w), 838 (w), 754 (w) cm–1. 1H NMR (400 MHz, DMSO-d6):
d = 10.01 (s, 2 H), 8.55 (s, 2 H), 7.49 (s, 2 H), 7.39 (d, J = 8.4
Hz, 4 H), 6.82 (d, J = 8.4 Hz, 4 H), 4.65 (d, J = 16.0 Hz, 2
H), 4.48 (d, J = 16.0 Hz, 2 H), 4.25 (q, J = 7.2 Hz, 2 H), 4.15
(q, J = 7.2 Hz, 2 H), 1.25 (t, J = 7.2 Hz, 3 H), 1.21 (t, J = 7.2
Hz, 3 H). 13C NMR (100 MHz, DMSO-d6): d = 158.41,
157.03, 137.44, 133.09, 132.09, 123.89, 120.56, 115.93,
References and Notes
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N. She et al.
LETTER
112.25, 94.54, 85.89, 82.28, 74.10, 62.88, 43.30, 13.75.
ESI–MS: m/z = 621.2 [M + H]+, 643.2 [M + Na]+.
1466 (m), 1408 (m), 1391 (m), 1279 (m), 1031 (w), 856 (w),
773 (w) cm–1. 1H NMR (400 MHz, DMSO-d6): d = 8.60 (s,
2 H), 8.09 (s, 2 H), 7.94 (d, J = 8.0 Hz, 4 H), 7.67 (d, J = 8.0
Hz, 4 H), 7.65 (s, 2 H), 7.51 (s, 2 H), 4.71 (d, J = 16.0 Hz, 2
H), 4.53 (d, J = 16.0 Hz, 2 H), 4.26 (q, J = 7.2 Hz, 2 H), 4.15
(q, J = 7.2 Hz, 2 H), 1.26 (t, J = 7.2 Hz, 3 H), 1.21 (t, J = 7.2
Hz, 3 H). 13C NMR (100 MHz, DMSO-d6): d =167.02,
166.39, 165.94, 157.01, 138.62, 134.49, 132.62, 131.24,
128.01, 124.61, 123.48, 93.43, 89.14, 82.24, 74.12, 62.90,
62.67, 43.28, 13.75. ESI–MS: m/z = 675.2 [M + H]+, 697.2
[M + Na]+. Compound 5h: IR (KBr): 3321 (m), 3103 (w),
3042 (w), 2983 (w), 2210 (w), 1707 (s), 1594 (m), 1525 (s),
1465 (m), 1404 (w), 1371 (w), 1313 (s), 1257 (m), 1033 (w),
836 (w), 764 (w) cm–1. 1H NMR (400 MHz, DMSO-d6): d =
10.18 (s, 2 H), 8.56 (s, 2 H), 7.66 (d, J = 8.4 Hz, 4 H), 7.53
(d, J = 8.4 Hz, 4 H), 7.50 (s, 2 H), 4.68 (d, J = 16.0 Hz, 2 H),
4.49 (d, J = 16.0 Hz, 2 H), 4.25 (q, J = 7.2 Hz, 2 H), 4.15 (q,
J = 7.2 Hz, 2 H), 2.07 (s, 6 H), 1.25 (t, J = 7.2 Hz, 3 H), 1.21
(t, J = 7.2 Hz, 3 H). 13C NMR (100 MHz, DMSO-d6): d =
168.62, 165.91, 156.97, 140.05, 137.77, 132.21, 132.06,
123.76, 118.92, 116.07, 94.15, 86.79, 82.27, 74.07, 62.84,
62.61, 43.28, 24.06, 13.75. ESI–MS: m/z = 703.2 [M + H]+,
725.2 [M + Na]+.
Compound 5d: IR (KBr): 3347 (w), 3219 (w), 2981 (w),
2937 (w), 2207 (w), 1760 (s), 1742 (s), 1710 (s), 1604 (m),
1513 (s), 1467 (m), 1289 (m), 1247 (s), 1140 (m), 1028 (s),
832 (m), 753 (w) cm–1. 1H NMR (400 MHz, CDCl3): d =
7.43 (s, 2 H), 7.41 (d, J = 8.8 Hz, 4 H), 6.81 (d, J = 8.8 Hz,
4 H), 6.14 (s, 2 H), 4.75 (d, J = 16.0 Hz, 2 H), 4.33 (d, J =
16.0 Hz, 2 H), 4.24 (q, J = 7.2 Hz, 2 H), 4.18 (q, J = 7.2 Hz,
2 H), 3.76 (s, 6 H), 1.26 (t, J = 7.2 Hz, 3 H), 1.22 (t, J = 7.2
Hz, 3 H). 13C NMR (100 MHz, CDCl3): d = 165.84, 159.82,
156.96, 135.58, 133.16, 132.54, 125.73, 115.24, 114.04,
94.46, 86.55, 76.25, 63.71, 55.31, 44.32, 13.99. ESI–MS:
m/z = 649.2 [M + H]+, 671.3 [M + Na]+. Compound 5e: IR
(KBr): 3375 (w), 3061 (w), 2849 (w), 1754 (s), 1731 (s),
1702 (s), 1595 (s), 1458 (s), 1284 (m), 1136 (w), 1032 (w),
821 (w), 767 (w) cm–1. 1H NMR (400 MHz, CDCl3): d = 8.62
(d, J = 4.8 Hz, 4 H), 7.61 (s, 2 H), 7.37 (d, J = 4.8 Hz, 4 H),
6.08 (s, 2 H), 4.87 (d, J = 16.0 Hz, 2 H), 4.46 (d, J = 16.0 Hz,
2 H), 4.34 (q, J = 7.2 Hz, 2 H), 4.27 (q, J = 7.2 Hz, 2 H), 1.35
(t, J = 7.2 Hz, 3 H), 1.29 (t, J = 7.2 Hz, 3 H). 13C NMR (100
MHz, CDCl3): d = 165.35, 156.68, 149.89, 137.24, 133.25,
130.88, 125.42, 124.90, 91.71, 91.34, 82.78, 82.45, 63.65,
44.24, 14.01. ESI–MS: m/z = 591.1 [M + H]+, 613.0 [M +
Na]+. Compound 5f: IR (KBr): 3576 (w), 3203 (w), 2975
(w), 2938 (w), 2677 (m), 1759 (s), 1703 (s), 1474 (m), 1278
(m), 1033 (m), 807 (w), 768 (w) cm–1. 1H NMR (400 MHz,
CDCl3): d = 8.77 (s, 2 H), 8.59 (s, 2 H), 7.81 (d, J = 8.0 Hz,
2 H), 7.58 (s, 2 H), 7.30 (d, J = 8.0 Hz, 2 H), 6.97 (s, 2 H),
4.85 (d, J = 16.0 Hz, 2 H), 4.43 (d, J = 16.0 Hz, 2 H), 4.32
(q, J = 7.2 Hz, 2 H), 4.22 (q, J = 7.2 Hz, 2 H), 1.33 (t, J = 7.2
Hz, 3 H), 1.26 (t, J = 7.2 Hz, 3 H). 13C NMR (100 MHz,
CDCl3): d = 165.82, 165.50, 157.05, 152.00, 148.83, 138.49,
136.84, 132.96, 124.94, 90.98, 90.47, 82.74, 73.67, 63.64,
63.42, 44.18, 13.99, 13.81. ESI–MS: m/z = 591.1 [M + H]+,
613.0 [M + Na]+. Compound 5g: IR (KBr): 3355 (s), 3200
(s), 2984 (w), 1753 (s), 1703 (s), 1711 (s), 1665 (s), 1609 (s),
(19) Crystal Data for Compound 5a: C35H32N4O7, MW =
620.65, triclinic, a = 10.133(12), b = 11.903(13), c =
14.938(17) Å, a = 68.396(2)°, b = 77.801(2)°, g =
67.511(2)°, V = 1543(3) Å3, T = 292(2) K, space group P1,
Z = 2, m(Mo–Ka) = 0.094 mm–1, 5369 reflections measured,
2915 unique (Rint = 0.1322) which were used in all
calculations. The final wR2 (F2) was 0.1957 (all data).
CCDC-650493 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
at www.ccdc.cam.ac.uk/conts/retrieving.html or from the
Cambridge Crystallographic Data Center, 12, Union Road,
Cambridge CB2 1EZ, UK; fax: +44 (1223)336033; email:
deposit@ccdc.cam.ac.uk.
Synlett 2007, No. 16, 2533–2536 © Thieme Stuttgart · New York