Synthesis of alkoxynitrostilbenes as chromophores for nonlinear optical materials

Article abstract of DOI:10.1055/s-2007-990808

The synthesis of different unsymmetrical new alkoxy-nitrostilbenes bearing one or two monomers groups, as optimized nonlinear optical (NLO) chromophores, are described herein. The considered functions were acrylate and triethoxysilyl groups. The goal is t

Full text of DOI:10.1055/s-2007-990808

PAPER
3333
Synthesis of Alkoxynitrostilbenes as Chromophores for Nonlinear Optical
Materials
Synthesis of
A
lkox
i
ynitros
n
tilbenes
a
s
C
c
hromophor
e
es for
N
L
O
n
M
aterials t Diemer,a Hélène Chaumeil,*a Albert Defoin,a Christiane Carréb
a
Laboratoire de Chimie Organique et Bioorganique, CNRS UMR 7015, Ecole Nationale Supérieure de Chimie de Mulhouse,
Université de Haute Alsace, 3 rue Alfred Werner, 68093 Mulhouse Cedex, France
Fax +33(3)89336875; E-mail: helene.chaumeil@uha.fr
FOTON, CNRS UMR 6082, GET-ENST Bretagne, Département Optique, Technopôle Brest Iroise, CS 83818,
29238 Brest Cedex, France
b
Received 4 May 2007; revised 24 July 2007
synthesis of co-condensable or co-polymerizable com-
pounds bearing monomeric groups at the end of spacer
chains has been undertaken. Two kinds of monomers have
been studied containing a triethoxysilyl and/or an acrylate
Abstract: The synthesis of different unsymmetrical new alkoxy-
nitrostilbenes bearing one or two monomers groups, as optimized
nonlinear optical (NLO) chromophores, are described herein. The
considered functions were acrylate and triethoxysilyl groups. The
goal is to synthesize molecules with a large quadratic NLO polariz- group. In the first approach, two chains of same the type
ability and relative high solubility in photopolymerizable media that
were dissymmetrically anchored on the stilbene core
could also be permanently frozen by orientation in an electric field
and photopolymerization.
(Figure 1), so as to increase the chromophore solubility in
the host matrix. Moreover, the presence of two co-con-
densable or co-polymerizable functions would potentially
allow a covalent, rigid linkage to the host matrix. The in-
Key words: chromophores, stilbene, monomers, crossed mono-
mers, nonlinear optics
troduction of both acrylate and triethoxysilyl moieties on
the same molecule was also considered. Then, in order to
The microstructuration of photopolymerizable systems
doped with chromophores possessing a large quadratic
nonlinear optic (NLO) polarizability is well established
for the formation of new performing, rapid, and perma-
nent wave-guide devices.1 However, to improve the effi-
ciency of electro-optic organic materials, some
characteristics of the chromophores used at present must
be enhanced, such as their solubilities or their orientated
life times after applying an electric field. Thus, it is neces-
sary to synthesize new molecules. In addition, the use of
photopolymerizable hybrid sol-gel (HSG) would be ad-
vantageous for appreciable future improvements. Their ri-
gidity is quite similar to those of glasses and it is given by
the inorganic part of the sol, thus NLO chromophores are
easily incorporated. Using non-uniform illumination, it is
possible to induce spatially controlled photopolymeriza-
tion of the organic part, leading so to microstructuration
and photo-patterning of the optical properties.2 The pres-
ence of the organic part allows the dissipation of the me-
chanical constraints that appear during polymerization.
Here, the choice of the type of chromophore is critical.
These molecules must be soluble in the HSG matrix, pos-
sess high NLO properties, and should not absorb at the ac-
avoid a possible twist and/or folding back of the stilbene
core during polymerization, the synthesis of two stilbenes
bearing only a single side chain terminated by a trieth-
oxysilyl ether group was considered. The side chain of
stilbene 4 includes, in addition to a triethoxysilyl group, a
carbamate function, while the side chain of 5 includes
only the triethoxysilyl group. The aim was to study the in-
fluence of the nature of the chain on the optical properties
of the reactive medium, after incorporation of these two
specific stilbene compounds in the sol-gel matrix.
R2
O2N
R1
1 R1 = CH2OR2; R2 = OCONH(CH2)3Si(OEt)3
2 R1 = CH2OR2; R2 = O(CH2)3OCOCH=CH2
3 R1 = CH2OCONH(CH2)3Si(OEt)3; R2 = O(CH2)3OCOCH=CH2
4 R1 = H; R2 = OCONH(CH2)3Si(OEt)3
5 R1 = H; R2 = O(CH2)3Si(OEt)3
Figure 1
tinic wavelength. Chromophores with an azobenzene unit Customization of an organic optical material based on the
have been widely studied in the past but they have the dis- incorporation of new stilbenes compounds in a polymer
advantages of being largely absorbent until 700 nm.3 On matrix requires large amounts of materials for its chemical
the other hand, alkoxynitrostilbene derivatives with a and optical characterization, as well as the development of
more restricted spectra have emerged as molecules of
new applications. As a consequence, from the many re-
great interest. Taking into account all this information, the ported synthetic methodologies for the synthesis of stil-
benes we used those published by Cullinane.4 In our case,
this condensation between 2-(carboxymethyl)-5-nitroben-
SYNTHESIS 2007, No. 21, pp 3333–3338
Advanced online publication: 21.09.2007
DOI: 10.1055/s-2007-990808; Art ID: T07907SS
© Georg Thieme Verlag Stuttgart · New York
x
x.
x
x
.
2
0
0
7
zoic acid (6) and 4-hydroxybenzaldehyde gave 7
(Scheme 1) and allowed for the use of large quantities of
inexpensive starting materials in spite of the moderate

3334
V. Diemer et al.
PAPER
COOH
HNO3
COOH
COOH
O
NH (CH2)3Si(OEt)3
O
OCN(CH2)3Si(OEt)3
Et3N, r.t., 36 h, 56%
COOH
O2N
10
6
O
O
O2N
6, piperidine
140 °C, 3 h, 30%
OH
H
O
NH (CH2)3Si(OEt)3
OH
1
Scheme 2
7
NO2
O2N
COOH
Br
OH
piperidine
140 °C, 3 h, 75%
CH2Cl2, P2O5
CH2(OCH3)2
64%
1) Et3N, ClCO2Et
–20 °C, 30 min
COOH
O
2) NaBH4
(CH2)3OMOM
0 °C, 2 h, 69%
NO2
Br
O
O
11
O
O
NaOH, Bu4NBr
10
O
O
(CH2)3OMOM
12
O2N
45 °C, 64 h, 55%
8
HO
OH
HCl, MeOH
45 °C, 18 h, 64%
9
O2N
O
(CH2)3OH
K2CO3
~100%
O
OH
(CH2)3OH
O2N
13
O
73%
Et3N
18 h, r.t.
OH
Cl
10
O2N
Scheme 1
O
(CH2)3
O
O
yields (the initial diacid 6 was obtained according to
Borsche’s, or preferably according to Bihel’s, proce-
dure).5
O
Stilbene 8 was also obtained in 75% yield, by condensa-
tion of (4-nitrophenyl)acetic acid with 4-hydroxybenzal-
dehyde according to Cullinane’s procedure.4
O2N
(CH2)3 O
O
2
Two simultaneous reactions on 7 were achieved with eth-
yl chloroformate: the acylation of the phenol and the for-
mation of the mixed anhydride of the acid function.
Subsequently, the reduction of the mixed anhydride led to
acylated alcohol 9,6 which was deprotected to give the
free phenol 10. The synthesis of 10 allowed us to consider
the synthesis of derivatives bearing chains terminating in
co-condensable or co-polymerizable groups.
Scheme 3
The synthesis of the diacrylate 2 was easily achieved by a
three-step procedure from phenol 10 in 25% overall yield
(Scheme 3). Initially, both the alcohol and the phenol
functions were alkylated by reaction with the protected
alkyl bromide 11 in basic medium to give 12 in 55% yield.
The hydrolysis of the two methoxymethyl protecting
groups by treatment with 1 M hydrochloric acid overnight
afforded diol 13, which was diacylated with acryloyl chlo-
ride to provide diacrylate 2 in 73% yield.
The bis-silylated derivative 1 was readily obtained by ad-
dition of phenol 10 to excess 3-(triethoxysilyl)propyl iso-
cyanate in 56% yield (Scheme 2).
Synthesis 2007, No. 21, 3333–3338 © Thieme Stuttgart · New York

PAPER
Synthesis of Alkoxynitrostilbenes as Chromophores for NLO Materials
3335
As for compound 3 (Scheme 4), initially 10 was converted The alkylation of 8 with allyl bromide readily occurred in
into the monoacrylate 15 by reaction with 3-bromopropyl the presence of potassium carbonate to give 16 in excel-
acrylate (14), which was obtained according to literature lent yield. Then, according to a published procedure,8 the
procedures.7 The addition of 1.5 equivalents of 3-(tri- addition of triethoxysilane to the double bond of 16 af-
ethoxysilyl)propyl isocyanate gave the desired product 3. forded derivative 5. This reaction proceeded in 36% yield,
while the byproduct of reduction was obtained in 20%
O
yield.
Br(H2C)3
In summary, five new trans-alkoxynitrostilbenes 1–5
O
(CH2)3 O
O
O
have been readily synthesized. Note that during our exper-
iments, we have not isolated cis-stilbenes. The simulta-
neous photopolymerization of the organic part of the sol-
gel matrix and orientation of these new chromophores fol-
lowed by the final freeze of the material is presently being
studied in detail. Initial experiment have demonstrated the
feasibility of the process.9 However, the material that al-
lows photopatterning both in refractive index and in NLO
properties must be improved to reach the application re-
quirements of exploitable optical devices.
14
10
K2CO3, 60 °C
24 h, 65%
15
OH
O2N
OCN(CH2)3Si(OEt)3
Et3N, r.t., 40 h, 83%
O
(CH2)3
O
O
Reagents were purchased from commercial suppliers and used
without further purification. Solvents were of technical quality and
were distilled prior to use. Anhyd toluene was obtained freshly dis-
tilled from Na. Column chromatography was performed on silica
gel (particle size 63–200 mm, Macherey-Nagel GmBH, Düren, Ger-
many). TLC was performed on silica gel F254 aluminum sheets
(Merck, Darmstadt, Germany). All melting points were determined
with a Kofler hotplate apparatus. IR spectra were recorded with a
O
O
O2N
HN
(CH2)3Si(OEt)3
3
Scheme 4
Nicolet 205 FTIR spectrophotometer. 1H NMR (400 MHz) and 13
C
NMR (100.6 MHz) spectra were measured with a Bruker Avance
series 400 spectrometer with TMS as reference. Microanalyses
were performed by the Service de Microanalyse du CNRS at Ver-
naison, France. HRMS were measured with a Waters Micromass Q-
ToF Ultima API spectrometer at Basilea Pharmaceuticals in Basel,
Switzerland.
In order to obtain the carbamate 4 (Scheme 5), phenol 8
was allowed to react with 3-(triethoxysilyl)propyl isocy-
anate under basic conditions.
8
2-(Carboxymethyl)-5-nitrobenzoic acid (6)5 and 3-bromopropyl
acrylate (14)7 were prepared by literature procedures.
OCN(CH2)3Si(OEt)3
Et3N, r.t., 18 h, 76%
2-[(E)-2-(4-Hydroxyphenyl)vinyl]-5-nitrobenzoic Acid (7)
A mixture of 2-(carboxymethyl)-5-nitrobenzoic acid (6, 1.7 g, 7.5
mmol), 4-hydroxybenzaldehyde (737 mg, 6.0 mmol), and piperi-
dine (0.747 mL, 7.5 mmol) was stirred at 140 °C for 3 h. The crude
product was crystallized by dissolution in MeOH and evaporation.
These crystals were washed with EtOAc (25 mL), and then sus-
pended in H2O–s-BuOH (3.8:6.2, 8 mL) and AcOH (1.5 equiv) was
added. (A molar excess of AcOH was needed otherwise the only pi-
peridine salt of 7 was recovered.) This mixture was refluxed with
stirring and then stirring was maintained at r.t. for 3 h. The resultant
orange solid was filtered and rinsed with s-BuOH (10 mL) to give 7
(642 mg, 38%) as orange crystals; mp 270 °C.
NO2
allyl bromide, K2CO3
acetone reflux, 24 h, 92%
NO2
O
4
O
HN (CH2)3Si(OEt)3
O
IR (KBr): 3248, 3093, 3001, 1700, 1604, 1589, 1512, 1341, 1276,
1249, 1193, 1171, 964, 840, 811 cm–1.
16
1H NMR (400 MHz, CD3OD): d = 6.82 (d, J = 8.5 Hz, 2 H, H3¢, H5¢),
7.31 (d, J = 16.4 Hz, 1 Hvinyl), 7.48 (d, J = 8.5 Hz, 2 H, H2¢, H6¢), 7.95
(d, J = 16.4 Hz, 1 Hvinyl), 8.05 (d, J = 8.8 Hz, 1 H, H3), 8.32 (dd,
J = 8.8, 2.5 Hz, 1 H, H4), 8.7 (d, J = 2.5 Hz, 1 H, H6).
HSi(OEt)3, H2PtCl6
100 °C, 1.5 h, 36%
NO2
NO2
13C NMR (100.6 MHz, CD3OD): d = 116.6 (2 C), 123.2, 126.9,
127.0, 128.3, 129.3, 129.9 (2 C), 131.2, 136.4, 146.7, 147.0, 159.7,
169.1.
+ 20%
O
(CH2)3Si(OEt)3
O
5
Anal. Calcd for C15H11NO5 (285.25): C, 63.16; H, 3.89; N, 4.91.
Found: C, 62.85; H, 4.30; N, 4.97.
Scheme 5
Synthesis 2007, No. 21, 3333–3338 © Thieme Stuttgart · New York

3336
V. Diemer et al.
PAPER
2-[(E)-2-(4-Hydroxyphenyl)vinyl]-5-nitrobenzoic Acid, Piperi-
dine Salt
the mixture was stirred for 2 h. 1 M HCl was then added until neu-
tralization. This soln was extracted with EtOAc (3 × 50 mL), dried
(MgSO4), and concentrated under vacuum. The crude product was
refluxed in EtOAc (13.5 mL) and then allowed to warm to r.t. The
solid was filtered and rinsed with Et2O and then refluxed in toluene
(13.5 mL) and cooled to 0 °C. Filtration gave 10 (852 mg, ~100%)
as red crystals; mp 179–180 °C.
1H NMR (400 MHz, CD3OD): d = 1.62–1.74 (m, 2 H), 1.74–1.83
(m, 4 H), 3.02–3.18 (m, 4 H), 6.78 (d, J = 8.4 Hz, 2 H, H3¢, H5¢), 7.27
(d, J = 16.5 Hz, 1 Hvinyl), 7.45 (d, J = 8.4 Hz, 2 H, H2¢, H6¢), 7.64 (d,
J = 16.5 Hz, 1 Hvinyl), 7.92 (d, J = 8.5 Hz, 1 H, H3), 8.12 (d, J = 8.5
Hz, 1 H, H4), 8.3 (s, 1 H, H6).
13C NMR (100.6 MHz, CDCl3): d = 22.0, 22.8, 44.7, 115.6, 122.6,
122.8, 123.0, 125.5, 128.7, 129.0, 133.6, 141.0, 141.8, 146.0, 158.3,
174.4.
IR (KBr): 3499, 3210, 1599, 1577, 1511, 1501, 1322, 1307, 1268,
1244, 1226, 1206, 1169, 1085, 989 cm–1.
1H NMR (400 MHz, CD3OD): d = 4.84 (s, 2 H, CH2OH), 6.81 (d,
J = 8.6 Hz, 2 H, H2, H6), 7.26 (s, 2 H, Hvinyl), 7.48 (d, J = 8.6 Hz, 2
H, H3, H5), 7.87 (d, J = 8.5 Hz, 1 H, H6¢), 8.13 (dd, J = 8.5 Hz,
J = 2.3 Hz, 1 H, H5¢), 8.33 (d, J = 2.3 Hz, 1 H, H3¢).
Anal. Calcd for C20H22N2O5 (370.4): C, 64.85; H, 5.99; N, 7.56.
Found: C, 64.97; H, 5.75; N, 7.38.
4-[(E)-2-(4-Nitrophenyl)vinyl]phenol (8)
13C NMR (100.6 MHz, CD3OD): d = 62.4, 116.7 (2 C), 121.0,
123.4, 123.6, 126.8, 129.7 (2 C), 129.8, 135.9, 141.0, 144.1, 147.7,
159.6.
A mixture of (4-nitrophenyl)acetic acid (4 g, 22 mmol), 4-hydroxy-
benzaldehyde (2 g, 16.4 mmol), and piperidine (1 mL) was stirred
at 140 °C for 1 h under argon. The thus-obtained black solid was
crushed and then heated at reflux in EtOH–H2O (3:1, 20 mL) with
AcOH (0.1 mL). The mixture was then allowed to reach r.t. The ob-
tained suspended brown solid was filtered and recrystallized (i-
PrOH) to give 8 (2.97 g, 75%) as brown crystals; mp 206 °C (i-
PrOH) [Lit.10 204 °C].
1H NMR (400 MHz, CD3OD): d = 6.86 (d, J = 8.6 Hz, 2 H, H2, H6),
7.00 (d, J = 16.3 Hz, 1 H, Hvinyl), 7.21 (d, J = 16.3 Hz, 1 H, Hvinyl),
7.45 (d, J = 8.6 Hz, 2 H, H3, H5), 7.59 (d, J = 8.8 Hz, 2 H, H2¢, H6¢),
8.20 (d, J = 8.8 Hz, 2 H, H3¢, H5¢).
Anal. Calcd for C15H13NO4·0.5 H2O (280.28): C, 64.28; H, 5.03; N,
4.99. Found: C, 64.67; H, 5.02; N, 4.97.
4-[(E)-2-{4-Nitro-2-[({[3-(triethoxysilyl)propyl]carbam-
oyl}oxy)methyl]phenyl}vinyl]phenyl 3-(Triethoxysilyl)propyl-
carbamate (1)
To a suspension of phenol alcohol 10 (574 mg, 2.12 mmol) in
EtOAc (6 mL) were added, dropwise under argon, Et3N (0.294 mL,
2.12 mmol) then 3-(triethoxysilyl)propyl isocyanate (1.57 mL, 6.36
mmol). The mixture was stirred at r.t. for 36 h and then the solvent
was concentrated under vacuum. The crude product was washed
with i-Pr2O (3 × 4 mL), and then recrystallized (s-BuOH) to give
pure 1 (902 mg, 56%) as pale yellow crystals; mp 132–133 °C (s-
BuOH).
13C NMR (100.6 MHz, CD3OD): d = 116.6 (2 C), 124.2, 124.9 (2
C), 127.6 (2 C), 129.4, 129.6 (2 C), 134.5, 146.2, 147.5, 159.5.
Ethyl4-{(E)-2-[2-(Hydroxymethyl)-4-nitrophenyl]vinyl}phenyl
Carbonate (9)
IR (KBr): 3324, 2974, 2928, 2884, 1713, 1705, 1541, 1520, 1504,
1345, 1283, 1258, 1234, 1216, 1196, 1168, 1124, 1104, 1081, 1053,
959, 937, 793, 780 cm–1.
Compound 7 (3.2 g, 11.3 mmol) was suspended under ultrasonics in
THF (90 mL), Et3N (4.9 mL, 33.7 mmol) was added, and the mix-
ture was cooled to –20 °C and ethyl chloroformate (3.21 mL, 33.7
mmol) was added dropwise; the mixture was allowed to stir for 30
min. The salts were then filtered and rinsed with THF (10 mL).
NaBH4 (1.27 g, 33.7 mmol) in H2O (13 mL) was then added at 0 °C
to the filtrate. This mixture was stirred at 0 °C for 2 h and then 2 M
NH4Cl soln (8.4 mL) was added. The soln was extracted with
EtOAc (3 × 50 mL). The combined extracts were washed with aq 1
M HCl (50 mL) and brine (50 mL), dried (MgSO4), and concentrat-
ed under vacuum. The crude product was purified by chromatogra-
phy (cyclohexane–EtOAc, 1:1), and the solid product thus obtained
was washed (i-Pr2O, 5 mL) to yield 9 (2.67 g, 69%) as yellow crys-
tals; mp 108–109 °C (MeOH); Rf = 0.49 (cyclohexane–EtOAc,
1:1).
1H NMR (400 MHz, CD3OD): d = 0.59 (t, J = 8 Hz, 2 H,
CH2CH2CH2), 0.65 (t, J = 8 Hz, 2 Hchain), 1.18 (t, J = 7 Hz, 9 H,
CH3), 1.23 (t, J = 7 Hz, 9 H, CH3), 1.58 (quint, J = 8 Hz, 2 Hchain),
1.67 (quint, J = 8 Hz, 2 Hchain), 3.11 (t, J = 7.0 Hz, 2 Hchain), 3.18 (t,
J = 7.0 Hz, 2 Hchain), 3.79 (q, J = 7 Hz, 6 H, CH2), 3.84 (q, J = 7 Hz,
6 H, CH2), 5.34 (s, 2 H, CH2O), 7.15 (d, J = 8.5 Hz, 2 H, H2, H6),
7.33 (d, J = 16.1 Hz, 1 Hvinyl), 7.45 (d, J = 16.1 Hz, 1 Hvinyl), 7.65 (d,
J = 8.5 Hz, 2 H, H3, H5), 7.94 (d, J = 8.8 Hz, 1 H, H6¢), 8.19 (dd,
J = 8.8, 2.0 Hz, 1 H, H5¢), 8.29 (d, J = 2.0 Hz, 1 H, H3¢).
13C NMR (100.6 MHz, CD3OD): d = 8.5, 8.6, 18.8 (2 C), 24.4, 24.5,
44.8, 48.5, 59.6, 59.7, 64.7, 123.3, 124.1, 124.4, 125.3, 127.7,
129.4, 135.3, 135.5, 137.3, 144.4, 148.1, 153.3, 158.5.
IR (KBr): 3387, 2941, 2935, 2912, 1757, 1582, 1516, 1372, 1343,
1324, 1279, 1266, 1236, 1218, 1176, 1066, 1032, 1015, 996, 961,
952, 896, 828, 776, 750 cm–1.
Anal. Calcd for C35H55N3O12Si2 (766.01): C, 54.88; H, 7.24; N,
5.49. Found: C, 54.58; H, 7.28; N, 5.36.
1H NMR (400 MHz, CD3OD): d = 1.37 (t, J = 7.2 Hz, 3 H, CH3),
4.30 (q, J = 7.2 Hz, 2 H, CH2CH3), 4.87 (s, 2 H, CH2OH), 7.22 (d,
J = 8.8 Hz, 2 H, H2, H6), 7.34 (d, J = 16.2 Hz, 1 H, Hvinyl), 7.48 (d,
J = 16.2 Hz, 1 Hvinyl), 7.69 (d, J = 8.8 Hz, 2 H, H3, H5), 7.93 (d,
J = 8.8 Hz, 1 H, H6¢), 8.17 (dd, J = 8.8, 2.2 Hz, 1 H, H5¢), 8.35 (d,
J = 2.2 Hz, 1 H, H3¢).
13C NMR (100.6 MHz, CD3OD): d = 14.9, 62.3, 65.9, 122.6 (2 C),
123.4, 123.6, 124.7, 127.4, 129.3 (2 C), 131.1, 134.6, 141.7, 143.4,
148.2, 152.8, 155.0.
1-Bromo-3-(methoxymethoxy)propane (11)
To a vigorously stirred suspension of P2O5 (25 g, 175 mmol) and
formaldehyde dimethyl acetal (44.5 mL, 500 mmol) in anhyd
CH2Cl2 (45 mL) was added a soln of 3-bromopropan-1-ol (7 g, 50
mmol) in anhyd CH2Cl2 (45 mL) and the mixture was stirred at r.t
for 50 min. The soln was then added dropwise to Na2CO3 (5 g). The
organic layer was washed with 1 M HCl (10 mL) and H2O (10 mL).
After drying (MgSO4), the solvent was evaporated under vacuum.
The crude product was distilled under vacuum to give 11 (5.83 g,
64%); bp 69 °C/12 mbar [Lit.11 85 °C/32 mbar].
Anal. Calcd for C18H17NO6 (343.33): C, 62.97; H, 4.99; N, 4.08.
Found: C, 62.83; H, 5.09; N, 4.04.
2-{[3-(Methoxymethoxy)propoxy]methyl}-1-[(E)-2-{4-[3-meth-
oxymethoxy)propoxy]phenyl}vinyl]-4-nitrobenzene (12)
4-{(E)-2-[2-(Hydroxymethyl)-4-nitrophenyl]vinyl}phenol (10)
To a soln of ester 9 (1.044 g, 3.04 mmol) in MeOH (45 mL per 7.7
mmol) was added, under argon, K2CO3 (420 mg, 3.04 mmol) and
To 10 (1 g, 3.69 mmol) in toluene (33 mL) was added 11 (2.69 g,
14.7 mmol), 12.5 M NaOH (23.7 mL) and Bu4NBr (4.76 g, 14.7
mmol). The mixture was stirred at 45 °C for 64 h under argon in the
Synthesis 2007, No. 21, 3333–3338 © Thieme Stuttgart · New York

PAPER
Synthesis of Alkoxynitrostilbenes as Chromophores for NLO Materials
3337
dark. The solvent was then evaporated under vacuum. The residue
was dissolved in EtOAc (20 mL) and washed with H2O (5 mL). The
organic layer was separated and dried (MgSO4). EtOAc was re-
moved under vacuum. The crude product was purified by chroma-
tography (cyclohexane–EtOAc, 7:3) to give pure 12 (974 mg, 55%)
as a pale yellow oil; Rf = 0.33 (cyclohexane–EtOAc, 7:3).
1H NMR (400 MHz, CDCl3): d = 2.02 (quint, J = 6.3 Hz, 2 Hchain),
2.18 (quint, J = 6.3 Hz, 2 Hchain), 3.66 (t, J = 6.3 Hz, 2 H,
PhCH2OCH2), 4.09 (t, J = 6.3 Hz, 2 H, PhOCH2), 4.28 (t, J = 6.3
Hz, 2 H, CH2OCO), 4.37 (t, J = 6.3 Hz, 2 H, CH2OCO), 4.66 (s, 2
H, PhCH2O), 5.83 (dd, J = 10.3, 1.5 Hz, 1 H, CH2=CH), 5.79 (dd,
J = 10.3, 1.5 Hz, 1 H, CH2=CH), 6.10 (dd, J = 10.3, 17 Hz, 1 H,
CH=CH2), 6.11 (dd, J = 10.3, 17 Hz, 1 H, CH=CH2), 6.37 (dd,
J = 17, 1.5 Hz, 1 H, CH2=CH), 6.67 (dd, J = 17, 1.5 Hz, 1 H,
CH2=CH), 6.90 (d, J = 8.8 Hz, 2 H, H2, H6), 7.11, 7.19 (d, J = 16
Hz, 2 Hvinyl), 7.47 (d, J = 8.5 Hz, 2 H, H3, H5), 7.72 (d, J = 8.5 Hz,
1 H, H6¢), 8.11 (dd, J = 8.5, 2.2 Hz, 1 H, H5¢), 8.23 (d, J = 2.2 Hz, 1
H, H3¢).
IR (KBr): 3326, 2929, 2881, 1601, 1582, 1511, 1473, 1468, 1341,
1305, 1253, 1175, 1153, 1110, 1074, 1045, 919 cm–1.
1H NMR (400 MHz, CD3OD): d = 1.91, 2.06 (quint, J = 6.3 Hz, 4
Hchain), 3.28 (s, 3 H, CH3), 3.32 (s, 3 H, CH3), 3.63 (t, J = 6.3 Hz, 2
H, PhCH2OCH2), 3.70 (2 t, J = 6.3 Hz, 2 H, CH2OCH2O), 3.71 (2 t,
J = 6.3 Hz, 2 H, CH2OCH2O), 4.12 (t, J = 6.3 Hz, 2 H, PhOCH2),
4.53 (2 s, 2 H, OCH2O), 4.61 (2 s, 2 H, OCH2O), 4.72 (s, 2 H,
PhCH2O), 6.95 (d, J = 8.8 Hz, 2 H, H3¢, H5¢), 7.30 (d, J = 4.5 Hz, 2
13C NMR (100.6 MHz, CDCl3): d = 29.0, 29.4, 61.7, 62.0, 64.9,
67.7, 70.9, 115.3 (2 C), 121.5, 123.4, 124.3, 126.3, 128.7 (2 C),
128.8 (2 C), 129.8, 131.1, 131.3, 134.8, 136.8, 143.6, 146.7, 159.9,
166.5, 166.5.
Hvinyl), 7.56 (d, J = 8.8 Hz, 2 H, H2¢, H6¢), 7.91 (d, J = 8.5 Hz, 1 H,
H6), 8.15 (dd, J = 8.5, 2.2 Hz, 1 H, H5), 8.26 (d, J = 2.2 Hz, 1 H, H3).
Anal. Calcd for C27H29NO8 (495.52): C, 65.44; H, 5.90; N, 2.83.
Found: C, 65.41; H, 6.09; N, 2.66.
13C NMR (100.6 MHz, CD3OD): d = 30.7, 31.1, 55.4, 65.2, 65.7,
65.9, 68.7, 68.7, 71.2, 97.45, 97.4, 115.8 (2 C), 121.9, 123.8, 124.6,
126.9, 129.7 (2 C), 130.7, 135.4, 138.1, 144.5, 147.5, 161.1.
HRMS (ESI-Q-TOF): m/z [M]+ calcd for C25H33NO8: 475.221;
found: 475.217.
3-(4-{(E)-2-[2-(Hydroxymethyl)-4-nitrophenyl]vinyl}phen-
oxy)propyl Acrylate (15)
To 10 (565 mg, 2 mmol) in acetone (30 mL) were added, under ar-
gon, 3-bromopropyl acrylate (14, 530 mg, 2.7 mmol) and K2CO3
(287 mg, 2 mmol). The mixture was stirred at 60 °C for 24 h. Ace-
tone was evaporated under vacuum and the residue was then dis-
solved in Et2O (30 mL) and the salts were filtered off. After
removing the solvent under vacuum, the crude product was purified
by chromatography (cyclohexane–EtOAc–Et3N, 6:4:0.001) to give
pure 15 (643 mg, 84%) as orange crystals; mp 95–98 °C; Rf = 0.46
(cyclohexane–EtOAc–Et3N, 6:4:0.001).
3-{4-[(E)-2-{2-[(3-Hydroxypropoxy)methyl]-4-nitrophenyl}vi-
nyl]phenoxy}propan-1-ol (13)
Compound 12 (956 mg, 2.01 mmol) in 2 M HCl (3 mL) and MeOH
(36 mL) was heated under stirring at 45 °C under argon for 18 h. Af-
ter neutralization with Na2CO3, the mixture was extracted with
EtOAc (3 × 50 mL). The organic layers were dried (MgSO4) and
evaporated under vacuum. The crude product was purified by crys-
tallization in EtOAc–cyclohexane [or by chromatography (cyclo-
hexane–EtOAc, 8:2)] to give pure 13 (498 mg, 64%) as yellow-
orange crystals; mp 95 °C; Rf = 0.4 (cyclohexane–EtOAc, 8:2).
IR (KBr): 3547, 3539, 3532, 3369, 2925, 2905, 2881, 2362, 1721,
1598, 1577, 1515, 1503, 1407, 1338, 1323, 1295, 1256, 1200, 1176,
1086, 1051, 1014, 983, 812 cm–1.
IR (KBr): 3276, 2950, 2875, 1602, 1581, 1510, 1338, 1269, 1173,
1047 cm–1.
1H NMR (400 MHz, CDCl3): d = 2.19 (t, J = 6.3 Hz, 2 Hchain), 4.10
(t, J = 6.3 Hz, 2 H, PhOCH2), 4.34 (t, J = 6.3 Hz, 2 H, CH2OCO),
4.92 (s, 2 H, CH2OH), 5.85 (dd, J = 10.5, 1.5 Hz, 1 H, CH2=CH),
6.13 (dd, J = 10.5, 17.3 Hz, 1 H, CH=CH2), 6.42 (dd, J = 17.3, 1.5
Hz, 1 H, CH2=CH), 6.92 (d, J = 8.8 Hz, 2 H, H2, H6), 7.15 (dd,
J = 16 Hz, 2 H, Hvinyl), 7.49 (d, J = 8.8 Hz, 2 H, H3, H5), 7.76 (d,
J = 8.6 Hz, 1 H, H6¢), 8.16 (dd, J = 8.6, 2.3 Hz, 1 H, H5¢), 8.33 (d,
J = 2.3 Hz, 1 H, H3¢).
13C NMR (100.6 MHz, CDCl3): d = 28.5, 61.3, 62.5, 64.4, 114.8 (2
C), 120.8, 122.8, 123.0, 125.8, 128.2 (2 C), 128.5, 129.2, 131.0,
134.4, 138.8, 142.7, 146.4, 159.4, 166.2.
HRMS (ESI-Q-TOF): m/z [M]+ calcd for C21H21NO6: 383.1369;
found: 383.1374.
1H NMR (400 MHz, CD3OD): d = 1.88 (quint, J = 6.3 Hz, 2 Hchain),
2.0 (quint, J = 6.3 Hz, 2 Hchain), 3.68 (2t, J = 6.3 Hz, 2 H, CH2OH),
3.71 (2t, J = 6.3 Hz, 2 H, CH2OH), 3.75 (t, J = 6.3 Hz, 2 H,
PhCH2OCH2), 4.12 (t, J = 6.3 Hz, 2 H, PhOCH2), 4.74 (s, 2 H,
PhCH2O), 6.96 (d, J = 8.8 Hz, 2 H, H2, H6), 7.3 (d, J = 3.8 Hz, 2 Hvi-
nyl), 7.56 (d, J = 8.8 Hz, 2 H, H3, H5), 7.9 (d, J = 8.6 Hz, 1 H, H6¢),
8.16 (dd, J = 8.6 Hz, J = 2.2 Hz, 1 H, H5¢), 8.27 (d, J = 2.2 Hz, 1 H,
H3¢).
13C NMR (100.6 MHz, CD3OD): d = 33.3, 33.8, 59.5, 60.0, 65.8,
68.7, 71.2, 115.8 (2 C), 121.9, 123.8, 124.6 (2 C), 126.9, 129.7,
130.8, 135.5, 138.2, 144.6, 147.6, 161.2.
Anal. Calcd for C21H25NO6 (387.43): C, 65.10; H, 6.5; N, 3.62.
Found: C, 64.76; H, 6.63; N, 3.49.
3-{4-[(E)-2-{4-Nitro-2-[({[3-(triethoxysilyl)propyl]carbam-
oyl}oxy)methyl]phenyl}vinyl]phenoxy}propyl Acrylate (3)
To 15 (643 mg, 1.67 mmol) in EtOAc (8 mL) were added, under ar-
gon, Et3N (0.242 mL, 1.67 mmol) and 3-(triethoxysilyl)propyl iso-
cyanate (0.620 mL, 2.51 mmol) and the mixture was stirred at r.t.
for 40 h. The solvent was removed under vacuum and crude 3 was
3-{4-[(E)-2-(2-{[3-(Acryloyloxy)propoxy]methyl}-4-nitrophe-
nyl)vinyl]phenoxy}propyl Acrylate (2)
To a soln of 13 (556 mg, 1.42 mmol) in CH2Cl2 (52 mL) were add-
ed, under argon, Et3N (1.04 mL, 7.1 mmol) and at 0 °C acryloyl
chloride (350 mL, 4.31 mmol) and the mixture was stirred at r.t. for
18 h. This organic layer was then washed successively with aq 1 M
HCl (10 mL), H2O (10 mL), and sat. aq NaHCO3 (10 mL). The or-
ganic layer was dried (MgSO4) and the solvent was removed under
vacuum. The crude product was purified by chromatography (cy-
clohexane–EtOAc–Et3N, 7:3:0.001). The obtained crystals were af-
terwards washed with cyclohexane (3 × 2 mL) to afford pure 2 (514
mg, 73%) as yellow crystals; mp 68–69 °C; Rf = 0.5 (cyclohexane–
EtOAc–Et3N, 7:3:0.001).
purified
by
chromatography
(cyclohexane–EtOAc–Et3N,
7:3:0.001) to give pure 3 (871 mg, 83%) as yellow crystals;
mp 74–76 °C (cyclohexane); Rf = 0.46 (cyclohexane–EtOAc–Et3N,
7:3:0.001).
IR (KBr): 3305, 2976, 2928, 2882, 1721, 1687, 1602, 1582, 1546,
1515, 1406, 1345, 1332, 1293, 1255, 1195, 1176, 1101, 1078, 1056,
983, 960, 832, 812 cm–1.
1H NMR (400 MHz, CDCl3): d = 0.63 (q, J = 7 Hz, 2 H, SiCH2),
1.19 (t, J = 7 Hz, 9 H, CH3), 1.63 (m, 2 Hchain), 2.19 (t, J = 6.3 Hz, 2
IR (KBr): 3400, 2973, 2932, 2886, 2851, 1723, 1716, 1602, 1581,
1512, 1408, 1339, 1328, 1300, 1275, 1266, 1253, 1198, 1181, 1131,
1122, 1062, 985, 973, 832 cm–1.
Hchain), 3.23 (q, J = 6.3 Hz, 2 H, NHCH2), 3.81 (q, J = 7 Hz, 6 H,
SiCH2), 4.11 (t, J = 6.0 Hz, 2 H, PhOCH2), 4.38 (t, J = 6.3 Hz, 2 H,
Synthesis 2007, No. 21, 3333–3338 © Thieme Stuttgart · New York

3338
V. Diemer et al.
PAPER
CH2OCO), 5.3 (s, 2 H, PhCH2O), 5.84 (dd, J = 10.3, 1.2 Hz, 1 H,
CH2=CH), 6.12 (dd, J = 10.3, 17.3 Hz, 1 H, CH=CH2), 6.42 (dd,
J = 17.3, 1.2 Hz, 1 H, CH2=CH), 6.92 (d, J = 8.8 Hz, 2 H, H2, H6),
7.16 (dd, J = 16 Hz, 2 Hvinyl), 7.49 (d, J = 8.8 Hz, 2 H, H3, H5), 7.76
(d, J = 8.8 Hz, 1 H, H6¢), 8.16 (dd, J = 8.8, 2.2 Hz, 1 H, H5¢), 8.27 (d,
J = 2.2 Hz, 1 H, H3¢).
13C NMR (100.6 MHz, CDCl3): d = 7.6, 18.3 (3 C), 23.2, 28.6, 43.5,
58.5 (3 C), 61.3, 63.3, 64.5, 114.8 (2 C), 120.6, 123.3, 124.0, 125.9,
128.3 (2 C), 128.6, 129.2, 130.9, 134.7, 135.0, 143.0, 146.3, 155.9,
159.5, 166.2.
Triethoxy(3-{4-[(E)-2-(4-nitrophenyl)vinyl]phenoxy}propyl)si-
lane (5)
To compound 16 (564 mg, 2 mmol) dissolved in anhyd toluene (2
mL) was added triethoxysilane (0.440 mL, 2.4 mmol) and a soln of
H2PtCl6 in s-BuOH (10 mg in 10 mL, 0.3 mL), under argon. The
mixture was heated with stirring at 100 °C for 1.5 h. The solvent
was removed under vacuum. The crude product was purified by
chromatography (cyclohexane–EtOAc, 85:15) to give 5 (323 mg,
36%) as yellow crystals together with 4-nitro-4¢-propoxystilbene
(20%); mp 81–84 °C; Rf = 0.41 (cyclohexane–EtOAc 85:15).
IR (KBr): 751, 789, 847, 960, 1050, 1074, 1174, 1194, 1256, 1325,
1339, 1512, 1519, 1588, 1604, 2882, 2927, 2977 cm–1.
Anal. Calcd for C31H42N2O10Si (630.76): C, 59.03; H, 6.71; N, 4.44.
Found: C, 58.71; H, 6.67; N, 4.37.
1H NMR (400 MHz, CDCl3): d = 0.75–0.82 (m, 2 H, CH2Si), 1.23
(t, J = 6.8 Hz, 9 H, CH3), 1.93 (m, 2 Hchain), 3.84 (q, J = 6.8 Hz, 6 H,
SiOCH2), 3.98 (t, J = 6.5 Hz, 2 H, OCH2), 6.91 (d, J = 8.8 Hz, 2 H,
H2, H6), 6.99 (d, J = 16.4 Hz, 1 Hvinyl), 7.22 (d, J = 16.4 Hz, 1 Hvinyl),
7.47 (d, J = 8.8 Hz, 2 H, H3, H5), 7.59 (d, J = 8.8 Hz, 2 H, H3¢, H5¢),
8.20 (d, J = 8.8 Hz, 2 H, H2¢, H6¢).
13C NMR (100.6 MHz, CDCl3): d = 6.6, 18.4 (3 C), 22.9, 58.6 (3 C),
70.1, 115.0 (2 C), 124.0, 124.3 (2 C), 126.6 (2 C), 128.5 (2 C), 128.8
(2 C), 133.1, 144.5; 146.5, 159.9.
4-[(E)-2-(4-Nitrophenyl)vinyl]phenyl [3-(Triethoxysilyl)pro-
pyl]carbamate (4)
Compound 8 (1 g, 4.05 mmol), 3-(triethoxysilyl)propyl isocyanate
(1.1 mL, 4.45 mmol), and Et3N (0.280 mL, 2.02 mmol) were dis-
solved in EtOAc (12 mL). The mixture was allowed to react at r.t.
for 18 h under argon. The solvent was removed under vacuum. The
crude product was recrystallized (s-BuOH) to give pure 4 (1.5 g,
76%) as yellow crystals; mp 105 °C (s-BuOH).
IR (KBr): 2975, 2927, 2884, 1745, 1591, 1527, 1511, 1503, 1339,
1227, 1206, 1168, 1108, 1172, 1072, 996, 978, 956, 850, 814, 791,
767, 751, 533 cm–1.
Anal. Calcd for C23H31NO6Si (445.58): C, 62.00; H, 7.01; N, 3.14.
Found: C, 67.71; H, 6.86; N, 3.09.
1H NMR (400 MHz, CDCl3): d = 0.69 (t, J = 8.3 Hz, 2 H, CH2Si),
1.25 (t, J = 7.0 Hz, 9 H, CH3), 1.72 (quint, J = 6.3 Hz, 2 Hchain), 3.29
(dt, J = 6.3 Hz, 2 H, NHCH2), 3.85 (q, J = 7.0 Hz, 6 H, SiOCH2),
5.42 (t, J = 6.3 Hz, 1 H, NH), 7.07 (d, J = 16.3 Hz, 17 Hz, 1 Hvinyl),
7.16 (d, J = 8.5 Hz, 2 H, H2, H6), 7.24 (d, J = 16.3 Hz, 1 Hvinyl), 7.54
(d, J = 8.5 Hz, 2 H, H3, H5), 7.62 (d, J = 8.8 Hz, 2 H, H3¢, H5¢), 8.21
(dd, J = 8.8 Hz, 2 H, H2¢, H6¢).
13C NMR (100.6 MHz, CD3OD): d = 8.6, 18.8 (3 C), 24.4, 44.8,
59.7 (3 C), 123.3 (2 C), 125.1 (2 C), 127.5 (2 C), 128.3 (2 C), 129.2,
133.7, 135.2, 145.7, 148.2, 153.1, 157.1.
Acknowledgement
The Région Alsace, the program Interreg IIIA Rhenaphotonics are
gratefully acknowledged for their financial support. The authors are
indebted to Dr. Mathias Wind for recording mass spectra. The au-
thors would like to thank Dr. Celine Croutxe-Barghorn and Dr. Loïc
Mager for their valuable help in guiding this research work and for
numerous fruitful comments.
References
Anal. Calcd for C24H32N2O7Si (488.61): C, 59.00; H, 6.60; N, 5.73.
Found: C, 58.72; H, 6.73; N, 5.61.
(1) Bombenger, J. P.; Mager, L.; Fort, A.; Carre, C. Appl. Surf.
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1-(Allyloxy)-4-[(E)-2-(4-nitrophenyl)vinyl]benzene (16)
To a soln of 8 (964 mg, 4 mmol) in acetone (4 mL) were added
K2CO3 (552 mg, 4 mmol) and allyl bromide (0.398 mL, 4.6 mmol)
under argon. The mixture was heated at reflux for 24 h. H2O (70
mL) was then added. This aqueous soln was extracted with CH2Cl2
(3 × 70 mL). The organic layers were dried (MgSO4). The soln was
reduce to ca. 20 mL under vacuum and filtered through Celite. The
solvent was then removed under vacuum to give 16 (1.046 mg,
92%) as yellow crystals; mp 113 °C.
(2) (a) Müh, E.; Stieger, M.; Klee, J. E.; Frey, H.; Mülhaupt, R.
J. Polym. Sci., Part A: Polym. Chem. 2001, 39, 4274.
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Solid Films 2002, 417, 95. (b)Harada, K.; Itoh, M.; Yatagai,
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(5) (a) Borsche, V.; Diakont, K.; Hanau, H. Ber. Dtsch. Chem.
Ges. B 1934, 67, 675. (b) Bihel, F.; Quéléver, G.; Lelourd,
H.; Petit, A.; Alvès da Costa, C.; Pourquié, O.; Checler, F.;
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2003, 11, 3141.
(6) Ishizumi, K.; Koga, K.; Yamada, S.-I. Chem. Pharm. Bull.
1968, 16, 192.
(7) Dudosclard-Gottardi, C.; Caubère, P.; Fort, Y. Tetrahedron
1995, 51, 2561.
(8) Belyakova, Z. V.; Pomerantseva, M. G.; Bykovchenko, V.
G.; Chemyshev, E. A. Zh. Obshch. Khim. 1976, 46, 1034; J.
Gen. Chem. USSR 1976, 46, 1030.
(9) Feuillade, M.; Croutxe-Barghorn, C.; Carre, C. OSA Trends
in Optics and Photonics - Photorefractive Effects, Materials,
and Devices 2005, 99, 294.
IR (KBr): 530, 749, 811, 828, 840, 918, 952, 963, 990, 1104, 1110,
1178, 1219, 1255, 1268, 1298, 1305, 1320, 1336, 1502, 1508, 1573,
1589, 1604, 2995, 3037 cm–1.
1H NMR (400 MHz, CDCl3): d = 4.58 (dt, J = 5.3, 1.5 Hz, 2 H,
CH2O), 5.31 (dq, J = 10.6, 1.5 Hz, 1 Hallyloxy), 5.43 (dq, J = 17.1, 1.5
Hz, 1 Hallyloxy), 6.07 (ddt, J = 17.1, 10.6, 5.3 Hz, 1 Hallyloxy), 6.94 (d,
J = 8.8 Hz, 2 H, H2, H6), 7.00 (d, J = 16.2 Hz, 1 Hvinyl), 7.22 (d,
J = 16.2 Hz, 1 Hvinyl), 7.49 (d, J = 8.8 Hz, 2 H, H3, H5), 7.59 (d,
J = 8.8 Hz, 2 H, H3¢, H5¢), 8.20 (d, J = 8.8 Hz, 2 H, H2¢, H6¢).
13C NMR (100.6 MHz, CD3OD): d = 69.0 (2 C), 115.2 (2 C), 118.1,
124.3 (2 C), 126.6 (2 C), 128.5 (2 C), 129.2, 133.0, 133.1, 144.4,
146.5, 159.4.
Anal. Calcd for C17H15NO3 (281.31): C, 72.58; H, 5.37; N, 4.98.
Found: C, 72.47; H, 5.34; N, 4.87.
(10) Güsten, H.; Salzwedel, M. Tetrahedron 1967, 23, 173.
(11) Hu, T. Q.; Weiler, L. Can. J. Chem. 1994, 72, 1512.
Synthesis 2007, No. 21, 3333–3338 © Thieme Stuttgart · New York