Synthesis of alkyloxy stilbenes by one-pot O-alkylation-Wittig and O-alkylation-Wittig-Heck reaction sequence

Article abstract of DOI:10.1016/j.tetlet.2012.10.102

A new route for the synthesis of alkyloxy stilbenes from hydroxy benzaldehydes is developed by a combination of one-pot reactions. Tandem one-pot O-alkylation-Wittig and O-alkylation-Wittig-Heck reactions offer a simple access to conjugated alkyloxy stilbenes. A highly conjugated tetra(p-alkyloxystyryl)benzene was synthesized from 1,2,4,5-tetrabromobenzene involving a series of one-pot operations following the O-alkylation-Wittig-Heck scheme.

Full text of DOI:10.1016/j.tetlet.2012.10.102

Tetrahedron Letters 54 (2013) 80–84
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Tetrahedron Letters
journal homepage: www.elsevier.com/locate/tetlet
Synthesis of alkyloxy stilbenes by one-pot O-alkylation-Wittig
and O-alkylation-Wittig–Heck reaction sequence
⇑
Krupa N. Patel, Bola V. Kamath, Ashutosh V. Bedekar
Department of Chemistry, Faculty of Science, M.S. University of Baroda, Vadodara 390 002, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A new route for the synthesis of alkyloxy stilbenes from hydroxy benzaldehydes is developed by a
combination of one-pot reactions. Tandem one-pot O-alkylation-Wittig and O-alkylation-Wittig–Heck
reactions offer a simple access to conjugated alkyloxy stilbenes. A highly conjugated tetra(p-alkyloxystyryl)
benzene was synthesized from 1,2,4,5-tetrabromobenzene involving a series of one-pot operations
following the O-alkylation-Wittig–Heck scheme.
Received 27 September 2012
Revised 20 October 2012
Accepted 23 October 2012
Available online 1 November 2012
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
One-pot reactions
O-Alkylation
Wittig reaction
Mizoroki–Heck reaction
Coupling reactions
Homogeneous catalysis
Conjugated molecules are important class of compounds due to
their applications in the area of material chemistry. Molecules with
Recently many attempts have been made to develop efficient pro-
tocols to achieve the one-pot synthesis of useful molecules.3 As
part of our interest in the synthesis of conjugated molecules from
simple starting material we have developed one-pot dehydrohalo-
genation–Heck or Wittig–Heck,4 Wittig–Suzuki,5 and oxidation-
Wittig–Heck6 reaction schemes. In continuation of these efforts,
in this communication we present a one-pot procedure for O-alkyl-
ation-Wittig and O-alkylation-Wittig–Heck reactions for the syn-
thesis of alkyloxy conjugated molecules. The two different
approaches developed for the synthesis of O-alkyloxystilbenes
are outlined in Scheme 1.
In Path A, 4-hydroxybenzaldehyde 2 was subjected to two
chemical transformations; firstly the aldehyde will undergo the
Wittig reaction with a ylide generated from the phosphonium salt
1 of benzylhalide and secondly the O-alkylation of hydroxyl group
with an appropriate alkylhalide. Since both the steps are taking
place in the basic medium one can conduct them simultaneously.
The availability of benzylhalide for the Wittig reaction can be a
limiting factor of this approach. This may be addressed by adopting
Path B, where the 4-hydroxybenzaldehyde may be converted into
4-alkyloxystyrene by the Wittig reaction with one carbon phos-
phonium salt 3 (CH3PPh3I) and alkylation of hydroxyl group. The
in situ generated 4-alkyloxystyrene can undergo the Pd catalyzed
Mizoroki–Heck reaction with an appropriate aryl halide. This ap-
proach may have wider applications due to easy availability of
functionalized aryl halides.
p-conjugation are capable of allowing the mobility of electrons
through continuous delocalization due to structural and orbital
arrangements. Several such molecules are utilized as photovoltaic
materials for solar cells, organic light emitting diodes, conducting
materials, liquid crystals, optical brighteners, gels, pharmaceutical
agents, DNA binding agents, sensors etc.1 The nature of substitu-
tion and the length of conjugation of these molecules mainly influ-
ence their properties. Typically the mobility of electrons is
controlled by choosing electron releasing or electron withdrawing
groups placed at the appropriate positions of the organic molecule.
In many studies the alkyloxy groups are selected as electron releas-
ing groups due to the simplicity of their synthesis from corre-
sponding phenols and the reasonable solubility of the resultant
materials in routine solvents.2 Generally the conjugation in the
molecule is built by condensation reactions namely Wittig, Knoe-
venagel, Perkin etc., or by metal mediated coupling reactions such
as Mizoroki–Heck or Sonogashira reactions.
Performing several chemical operations simultaneously in a sin-
gle vessel, also referred as the one-pot or domino or tandem reac-
tions has several distinct advantages. The compatible and
complimentary synthetic procedures can reduce the purifications
of the intermediate compounds, particularly important with unsta-
ble intermediates and may eventually save valuable resources.
Synthesis of alkyloxystilbenes by Path A was investigated and
the results are summarized in Table 1.
⇑
Corresponding author. Tel.: +91 0265 2795552.
E-mail address: avbedekar@yahoo.co.in (A.V. Bedekar).
0040-4039/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tetlet.2012.10.102

K. N. Patel et al. / Tetrahedron Letters 54 (2013) 80–84
81
Path A: O-Alkylation-Wittig
In the second approach the styrenes were synthesized by the
in situ reaction with appropriate aldehyde and one carbon Wittig
salt 3 and then subjected to the palladium catalyzed Mizoroki–
Heck reaction.8 This Path B was screened for a number of
aldehydes and aryl halides under the homogeneous Pd(OAc)2ꢀdppp
catalyst system with good overall yields, see Table 2. In this proto-
col the Mizoroki–Heck step determines the stereochemistry of
alkene and as expected the product was predominantly formed
as E isomer.9
The development of tandem reactions involving Mizoroki–Heck
reaction as one of the steps has also been investigated by others10
and by us.4,6 In Path B the in situ generated styrene by the reaction
of ylide from one carbon phosphonium salt 3 and a variety of alde-
hydes, were trapped to build stilbenes by the catalytic coupling
reaction. The approach involved an additional step in the one-pot
sequence but still the conversions were comparable with the first
process.
+
-
PPh3Br
K2CO3 (4 eq.)
1
OR
TBABr (0.1 eq.)
RX
+
OHC
DMA
140 oC, 40 h
2
OH
Path B: O-Alkylation-Wittig-Heck
X
Pd(OAc)2 (0.5 %)
-
dppp (1.0 %)
+
+
CH3PPh3I
K2CO3 (6 eq.)
TBABr (0.1 eq.)
3
+
OR
RX'
OHC
DMA
140 oC, 40 h
2
OH
Scheme 1. Two one-pot paths for the synthesis of O-alkyloxystilbene.
Certain small conjugated molecules also have significant appli-
cations in material chemistry due to their ability to transport
electrons from one part to the other within their framework.2,11
Some of the distyrylbenzenes with suitably placed alkyloxy substi-
tutions have useful optical properties.2d The present method was
As expected for a typical Wittig reaction,7 the stilbenes were
formed in a mixture of isomers with E olefin formed in excess.
The reaction conditions were not optimized and the products were
isolated in moderate to good yields.
Table 1
Synthesis of alkyloxystilbenes by Path Aa
OH
+
-
PPh3Br
R''' Br
R'
OHC
R''
6, R''' = C5H11
1, R' = H
4, R' = Br
2, R'' = H
5, R'' = OMe
7, R''' = CH2C6H5
8, R''' = CH2CH=CH2
No
1
Phosphonium salt
Aldehyde/Alkyl halide
Alkyloxystilbene
Yieldb (%) [E/Z]c
OC5H11
OCH2Ph
OCH2Ph
1
2/6
83 [69:31]
9
2
3
1
1
2/7
5/7
72 [76:24]
80 [57:43]
10
11
12
OMe
OC5H11
4
5
6
7
1
5
5
1
5/6
2/6
2/7
2/8
63 [72:28]
56 [65:35]
55 [57:43]
74 [71:29]
OMe
OC5H11
Br
Br
13
14
OCH2Ph
OCH2CH=CH2
15
8
1
Salisaldehyde/6
84 [84:16]
16
C5H11
O
a
b
c
Conditions: phosphonium salt (1.2 equiv), aldehyde (1.0 equiv), alkyl halide (1.2 equiv), K2CO3 (4 equiv), tetrabutylammonium bromide (TBAB) (10%), DMA, 140 °C, 40 h.
Isolated yield.
E/Z Ratio was determined by H NMR.

82
K. N. Patel et al. / Tetrahedron Letters 54 (2013) 80–84
Table 2
Synthesis of alkyloxystilbenes by Path Ba
OH
+
-
R''' Br
ArY
CH3PPh3I
3
OHC
R''
6, R''' = C5H11
7, R''' = CH2C6H5
17, R''' = C7H15
2, R'' = H
5, R'' = OMe
No
1
Aldehyde/Alkyl halide
ArY
Alkyloxystilbene
Yieldb/%
76
I
OC7H15
2/17
9
18
OCH2Ph
OC5H11
2
3
2/7
5/6
18
78
75
10
18
12
OMe
I
OC5H11
4
5
6
2/6
79
71
59
MeO
20
MeO
19
I
OC7H15
2/17
2/6
Me
22
Me
21
Br
OC5H11
Cl
24
Cl
23
Br
OC5H11
7
8
9
2/6
2/7
2/6
61
77
75
O2N
O2N
O2N
26
25
OCH2Ph
25
27
Br
OC5H11
C5H11
O
HO
29
28
a
Conditions: phosphonium salt 3 (1.2 equiv), aldehyde (1.2 equiv), alkyl halide (1.2 equiv), Aryl halide (1.0 equiv), K2CO3 (6 equiv), Pd(OAc)2 (0.5%), dppp (1.0%), TBAB
(10%), DMA, 140 °C, 40 h, alkyl halide (2.4 equiv).
b
Isolated yield; Mostly E isomer was formed.
then extended for the preparation of distyrylbenzenes having a
C6–C2–C6–C2–C6 framework. The reaction of 2,5-dimethoxy-1,
4-diiodobenzene 30 with aldehyde 2 or 5, phosphonium salt 3,
and appropriate alkyl halide primarily gave the E,E isomers of
distyrylbenzenes 31–34 by Path B, O-alkylation-Wittig–Heck one-
pot sequence, in good isolated yield. This process involved simulta-
neous two sets of such operations in one reaction setup, see Table 3.
Encouraged by the above result a set of polybrominated
aromatic compounds were subjected to the similar O-alkylation-
Wittig–Heck reaction sequence and the results are outlined in
Schemes 2 and 3. As representative examples, the dibromo arenes
36, 38, and 40 were converted into the corresponding bis-alkyloxy
alkene derivatives 37, 39,12 and 41, respectively. Several UV active
spots were detected in the reaction mixture but only the desired
E,E-isomer was isolated by column chromatography.
Table 3
Synthesis of distyrylbenzenea
OR'''
R''
OMe
I
OMe
OMe
R''
I
OMe
30
31 to 34
R'''O
No
Aldehyde/alkyl halide
Distyrylbenzene 31–34
Yieldb (%)
1
2
3
4
2/6
2/35
2/7
5/6
31, R00 = H, R000 = C5H11
32, R00 = H, R000 = C12H25
33, R00 = H, R000 = CH2Ph
34, R00 = OMe, R000 = C5H11
62
53
71
62
Similarly 1,3,5-tribromobenzene 42 and 1,2,4,5-tetrabromo-
benzene 44 were converted into the corresponding tri- and tetra-
a
Conditions: 30 (1.0 equiv), aldehyde (2.4 equiv), phosphonium salt
3
2c,13
stilbene derivatives 43 and 45, respectively.
The Pd-catalyzed
(2.4 equiv), alkyl halide (2.4 equiv), K2CO3 (12 equiv), Pd(OAc)2 (1.0%), dppp (2.0%),
Mizoroki–Heck reaction predominantly produces the E isomers of
43 and 45 which were isolated in low yield from the complex
TBAB (20%), DMA, 140 °C, 40 h.
b
Isolated yield; mostly E isomer was formed. 35 = C12H25Br.

K. N. Patel et al. / Tetrahedron Letters 54 (2013) 80–84
83
OC5H11
reaction mixture by careful column chromatography. The synthesis
was achieved by simultaneously performing several one-pot chem-
ical operations for 43 or 45, where the low yield could be compen-
sated by the simplicity and the practicability of the entire one-pot
process.
Me
Me
Br
37 %
The present study offers simple and efficient procedures for the
preparation of highly conjugated alkyloxystilbene derivatives by
one-pot O-alkylation-Wittig and O-alkylation-Wittig–Heck reac-
tion sequences.14
Br
36
37
OC5H11
Acknowledgment
OC5H11
We thank the University Grants Commission (UGC), New Delhi
for the award of Research Fellowship in Science for Meritorious
Students (RFSMS) to KNP.
Br
Br
References and notes
40 %
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Chem. Rev. 1996, 96, 115; (c) Muller, T. J. J In Metal Catalyzed Cascade Reactions;
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Int. Ed. 2005, 44, 1602; (e) Wasilke, J. O.; Obrey, S. J.; Baker, R. T.; Bazan, G. C.
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Nicolaou, K. C. Chem. Soc. Rev. 2009, 38, 2993; (h) Nicolaou, K. C.; Edmonds, D.
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38
39
OC5H11
Br
Br
31 %
40
OC5H11
C5H11
O
41
Scheme 2. Synthesis of conjugated compounds from dibromo arenes by Path B:
Conditions: Ar(Br)2 (1.0 equiv), aldehyde 2 (2.4 equiv), alkyl halide 6 (2.4 equiv),
phosphonium salt 3 (2.4 equiv), K2CO3 (12.0 equiv), TBAB (20.0%), Pd(OAc)2 (1.0%),
dppp (2.0%), DMA, 140 °C, 40 h. Isolated yield of E isomer.
C5H11
O
OC5H11
Br
Br
a
5. Chaudhary, A. R.; Bedekar, A. V. Appl. Organomet. Chem. 2012, 26, 430.
6. Saiyed, A. S.; Patel, K. N.; Kamath, B. V.; Bedekar, A. V. Tetrahedron Lett. 2012, 53,
4692.
7. Kolodiazhnyi, O. I. In Phosphorous Ylides—Chemistry and Applications in Organic
Synthesis; Wiley-VCH: Weinheim, 1999.
Br
42
8. (a) Mizoroki, T.; Mori, K.; Ozaki, A. Bull. Chem. Soc. Jpn. 1971, 44. 581-581; (b)
Heck, R. F.; Nolly, J. P. J. Org. Chem. 1972, 37, 2320–2322.
43
9. (a) de Meijere, A.; Meyer, F. E. Angew. Chem., Int. Ed. Engl. 1994, 33, 2379; (b)
Beletskaya, I. P.; Cheprakov, A. V. Chem. Rev. 2000, 100, 3009; (c) Jutand, A. In
The Mizoroki–Heck reaction; Oestreich, M., Ed.; John Wiley & Sons: Chichester,
United Kingdom, 2009; pp 1–50; (d) Amatore, C.; Jutand, A. Acc. Chem. Res.
2000, 33, 314.
OC5H11
C5H11O
10. (a) Salgado, A.; Mann, E.; Sanchez-Sancho, F.; Herradón, B. Heterocycles 2003,
60, 57; (b) Nandakumar, M. V.; Verkade, J. G. Tetrahedron 2005, 61, 9775; (c)
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Zhang, X.; Liu, A.; Chen, W. Org. Lett. 2008, 10, 3849; (f) Tu, S.; Xu, L.-H.; Yu, C.-
R. Synth. Commun. 2008, 38, 2662; (g) Burmester, C.; Mataka, S.; Thiemann, T.
Synth. Commun. 2010, 40, 3196.
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L.; Shieh, S.-J.; Lin, S.-C.; Liu, R.-S. Org. Lett. 2003, 5, 1131–1134; (c) Yan, Y.; Tao,
X.; Xu, G.; Zhao, H.; Sun, Y.; Wang, C.; Yang, J.; Yu, X.; Zhao, X.; Jiang, M. Aust. J.
Chem. 2005, 58, 29; (d) Shimizu, M.; Hiyama, T. Chem. Asian J. 2010, 5, 1516–
1531; (e) Thomas, R.; Varghese, S.; Kulkarni, G. U. J. Mater. Chem. 2009, 19,
4401–4406; (f) Lin, C.-H.; Tsai, C.-M.; Huang, G.-H.; Tao, Y.-T. Macromolecules
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114, 12508.
OC5H11
Br
Br
Br
b
Br
44
C5H11
O
45
OC5H11
Scheme 3. Synthesis of conjugated compounds from polybromo arenes by Path B:
Conditions: (a). Ar(Br)3 (1.0 equiv), aldehyde 2 (3.6 equiv), alkyl halide 6 (3.6 equiv),
phosphonium salt 3 (3.6 equiv), K2CO3 (18.0 equiv), TBAB (30.0 %), Pd(OAc)2 (1.5%),
12. He, J.; Xu, B.; Chen, F.; Xia, H.; Li, K.; Ye, L.; Tian, W. J. Phys. Chem. C 2009, 113,
9892.
13. Coya, C.; de Andrés, A.; Gómez, R.; Seoane, C.; Segura, J. L. J. Lumin. 2008, 128,
761.
dppp (3.0%), DMA, 140 °C, 40 h, [14%]. (b). Ar(Br)4 (1.0 equiv), aldehyde
2
(4.8 equiv), alkyl halide (4.8 equiv), phosphonium salt (4.8 eq.), K2CO3
6
3
(24.0 equiv), TBAB (40.0%), Pd(OAc)2 (2.0%), dppp (4.0%), DMA, 140 °C, 40 h, [17%].
Isolated yield of E isomer.

84
K. N. Patel et al. / Tetrahedron Letters 54 (2013) 80–84
14. Typical Procedure for O-alkylation–Wittig reaction:
MS (EI) (m/z): 296(M+, 100), 226(88), 225(55), 164(38), 152(17), 151(11).
IR (KBr) 2983, 2909, 2831, 1712, 1591, 1468, 1382, 1287, 1227, 1176, 1026,
968, 912, 802, 756, 696, 612, 542 cmꢂ1
Synthesis of 4-benzyloxy stilbene 10 (Table 1, entry 2):
t
A two-neck round bottom flask was charged with p-hydroxy benzaldehyde
(0.20 g, 1.63 mmol), benzyl triphenyl phosphine chloride (0.76 g, 1.96 mmol),
benzyl bromide (0.34 g, 1.96 mmol), dry potassium carbonate (0.91 g, 6.55
.
Characterization data of representative compounds:
1,4-Dimethoxy-2,5-bis(E)-[2-(4-pentyloxyphenyl)vinyl]benzene 31:
1H NMR (CDCl3, 400 MHz) d 0.96 (t, J = 7.2, 3H), 1.40-1.495 (m, 4H), 1.78-1.85
(q, J = 6.8 Hz, 2H), 3.94 (s, 3H), 4.00 (t, J = 6.8 Hz, 2H), 6.90-6.92 (m, 2H), 7.08 (d,
J = 16 Hz, 1H), 7.13 (s, 1H), 7.36 (d, J = 16.4 Hz, 1H), 7.49-7.51 (m, 2H).
MS (EI) (m/z): 514 (M+, 84), 513 (61), 129 (45), 97 (29), 95 (28), 83 (40), 81 (41),
73 (38), 71 (55), 68 (81), 57 (79), 56 (46), 55 (100).
mmol),
tetrabutylammonium
bromide
(0.05 g,
0.16 mmol),
and
dimethylacetamide (8 mL) under the nitrogen atmosphere. This reaction
mixture was stirred at 140 °C for 40 h and quenched with water and
extracted with ethyl acetate (3 ꢁ 25 mL). The combined organic phase was
washed with water and dried over anhydrous sodium sulfate. Solvent was
removed in vacuum and the crude product was purified by column
chromatography on silica gel and ethyl acetate petroleum ether (2:98) was
used as eluent to give 4-benzyloxy stilbene 10 (0.34 g, 72%) (The ratio of E:Z
isomers was determined to be 77:23 by 1H NMR).
IR (KBr)
t 3036, 3005, 2939, 2866, 1605, 1572, 1513, 1459, 1408, 1393, 1295,
1250, 1207, 1175, 1044, 1021, 964, 849, 804, 592, 523 cmꢂ1
.
9,10-bis(E)-[2-(4-Pentyloxyphenyl)vinyl]anthracene 39:
1H NMR (CDCl3, 400 MHz) d 0.96 (t, J = 7.2 Hz, 3H), 1.37–1.52 (m, 4H), 1.80–
1.87 (m, 2H), 4.03 (t, J = 6.8 Hz, 2H), 6.84–6.89 (m, 2H), 6.86 (d, 16.4 Hz, 1H),
6.98 (d, J = 8.4 Hz, 2H), 7.44–7.48 (m, 2H), 7.61 (d, J = 8.8 Hz, 2H), 7.78 (d,
J = 16.4 Hz, 1H), 8.38–8.42 (m, 2H).
1H NMR (CDCl3, 400 MHz) d 5.07(s, –CH2 protons of cis isomer), 5.12 (s, –CH2
protons of trans isomer), 6.53–6.60 (m, olefinic protons of cis isomer), 6.86–
6.89 (m, aromatic protons of both the isomers), 7.00–7.05 (m, aromatic protons
of cis and trans isomers and signal of trans olefinic proton with J = 16.4 Hz
merged in it), 7.11(d, olefinic proton of trans isomer), 7.22–7.32 (m, aromatic
protons of cis and trans isomers), 7.37–7.54 (m, aromatic protons of cis and
trans isomers).
MS (EI) (m/z): 555 (M+1,21), 554 (M+,100), 553 (56), 552 (35), 368 (9), 319 (6.6),
264 (6).
IR (KBr)
t 3010, 2932, 2866, 1603, 1573, 1510, 1469, 1246, 1173, 1021, 967,
760,529 cmꢂ1
.
MS (EI) (m/z): 287(M+1, 40), 286 (M+, 36), 285 (61), 196 (16), 195 (40), 194
(100), 164 (72), 151 (58), 91 (75), 90 (52).
4,4’-bis(E)-[2-(4-Pentyloxyphenyl)vinyl]-1,1’-biphenyl 41:
1H NMR (CDCl3, 400 MHz) d 0.96 (t, J = 7.2 Hz, 3H), 1.36–1.51 (m, 4H), 1.78–
1.85 (m, 2H), 3.99 (t, J = 6.8 Hz, 2H), 6.88–6.93 (m, 2H), 6.99–7.04 (m, 1H), 7.13
(d, J = 16.4 Hz, 1H), 7.31–7.38 (m, 1H), 7.43–7.51 (m, 3H), 7.57–7.65 (m,5H).
MS (EI) (m/z): 531 (M+1,22), 530 (M+), 529 (32), 454 (11), 266 (19), 205 (17),
190 (37), 104 (100), 91 (13).
IR (KBr)
t 3028, 2860, 1949, 1879, 1598, 1449, 1381, 1295, 1248, 1012, 964,
812, 689, 538 cmꢂ1
.
Typical Procedure for O-alkylation-Wittig–Heck reaction:
Synthesis of 3-methoxy-4-pentyloxy stilbene 12 (Table 2, entry 3):
A
two-neck round bottom flask was charged with iodobenzene (0.20 g,
IR (KBr) t 3067, 3037, 2968, 2930, 2823, 1617, 1582, 1534, 1470, 1272, 993,
0.98 mmol), 4-hydroxy 3-methoxy benzaldehyde (0.18 g, 1.176 mmol),
methyl triphenyl phosphine iodide (0.48 g, 1.176 mmol), pentyl bromide
(0.18 g, 1.176 mmol), dry potassium carbonate (0.81 g, 5.88 mmol),
palladium acetate (0.001 g, 0.0049 mmol), dppp (0.004 g, 0.0098 mmol),
tetrabutylammonium bromide (0.032 g, 0.098 mmol), and dimethylacet-
amide (8 mL) under the nitrogen atmosphere. This reaction mixture was
stirred at 140 °C for 40 h and quenched with water and extracted with ethyl
acetate (3 ꢁ 25 mL). The combined organic phase was washed with water and
dried over anhydrous sodium sulfate. Solvent was removed in vacuum and the
crude product was purified by column chromatography on silica gel and ethyl
acetate:petroleum ether (2:98) was used as eluent to give 3-methoxy
4-pentyloxy stilbene (0.22 g, 75 %).
880, 738, 577, 490 cm.-1
1,3,5-tris(E)-[2-(4-Pentyloxyphenyl)vinyl]benzene 43:
1H NMR (CDCl3, 400 MHz) d 0.94 (t, J = 7.2 Hz, 3H), 1.35-1.50 (m, 4H), 1.77–1.84
(m, 2H), 3.98 (t, J = 6.8 Hz, 2H), 6.91 (d, J = 8.8 Hz, 7.01 (d, J = 16 Hz, 1H), 7.14 (d,
J = 16.4 Hz, 1H), 7.47–7.49 (3H, doublet with J = 7.6 Hz (2H) and a singlet of
aromatic proton (1H) merged together).
MS (EI) (m/z): 642 (M+,62), 641 (100), 482 (72), 481 (70), 106 (18), 55 (13).
IR (KBr)
t 3024, 2936, 2866, 1694, 1606, 1583, 1510, 1472, 1250, 1173, 1025,
961, 840, 680, 550, 523 cm.-1
1,2,4,5-tetrakis(E)-[2-(4-Pentyloxyphenyl)vinyl]benzene 45:
1H NMR (CDCl3, 400 MHz) d 0.95 (t, J = 7.2 Hz, 3H), 1.37–1.51 (m, 4H), 1.79–
1.86 (m, 2H), 3.99–4.02 (t, J = 6.8 Hz, 2H), 6.91–6.93 (m, 2H), 7.02 (d, J = 16 Hz,
1H), 7.23 (d, J = 16.4 Hz, 1H), 7.48–7.54 (m, 2H), 7.86 (s, 1H).
MS (EI) (m/z): 846 (M+1), 610 (100), 470 (15), 107 (13).
1H NMR (CDCl3, 400 MHz) d 0.93 (t, J = 7.2 Hz, 3H, –CH3 protons of alkyl chain),
1.33–1.49 (m, 4H, –CH2–CH2 protons of alkyl chain), 1.83–1.90 (m, 2H, –CH2
protons of alkyl chain), 3.93 (s, 3H,–OCH3 protons), 4.03 (t, J = 7.2 Hz, 2H, –
OCH2– protons of alkyl chain), 6.86 (d, J = 8.4 Hz, 1H), 6.97 (d, J = 16 Hz, 1H,
olefinic proton), 7.02–7.08 (m, 3H, aromatic protons and doublet of olefinic
proton with J = 16 Hz merged in it), 7.22–7.26 (m, 1H), 7.33–7.37 (m, 2H),
7.49–7.51 (m, 2H).
IR (KBr)
t 3036, 2945, 2863, 1672, 1603, 1511, 1466, 1253, 1172, 1050, 959,
821, 589, 519 cmꢂ1
.