Solvent-free synthesis of ferrocenylethene derivatives

Article abstract of DOI:10.1016/S0022-328X(00)00927-X

Herein, we report a fast, mild, efficient and simple Wittig reaction in a dry state to get ferrocenylethene derivatives. The Z and E isomers can be separated by chromatography and many isomers are characterized for the first time.

Full text of DOI:10.1016/S0022-328X(00)00927-X

Journal of Organometallic Chemistry 625 (2001) 128–131
www.elsevier.nl/locate/jorganchem
Solvent-free synthesis of ferrocenylethene derivatives
Wan-yi Liu, Qi-hai Xu, Yong-xiang Ma *, Yong-min Liang, Ning-li Dong,
De-peng Guan
National Laboratory of Applied Organic Chemistry, Lanzhou Uni6ersity, Lanzhou 730000, People’s Republic of China
Received 19 October 2000; received in revised form 27 November 2000; accepted 29 November 2000
Abstract
Herein, we report a fast, mild, efficient and simple Wittig reaction in a dry state to get ferrocenylethene derivatives. The Z and
E isomers can be separated by chromatography and many isomers are characterized for the first time. © 2001 Elsevier Science
B.V. All rights reserved.
Keywords: Wittig reaction; Ferrocenylethene derivative; Solvent-free reaction; Z,E-separation
ferrocenylethene with various halides [2,10]; the third is
McMurry coupling of formylferrocene with other alde-
hydes [11]. But all those methods bear some disadvan-
tages, such as long reaction time, high temperature,
onerous operation, expensive reagents and low yield.
The solvent-free reaction has drawn great attention in
recent years [12], and has been proved to have many
advantages: reduced pollution, low costs, and simplicity
in process and handling. This prompted us to apply this
method to the synthesis of vinylferrocene derivatives by
the Wittig reaction. It should be pointed out that the
Wittig reaction has not been applied in dry state syn-
theses so far. Our work shows that the vinylferrocene
derivatives can be synthesized efficiently by the Wittig
reaction in solvent-free conditions
1
. Introduction
Considerable work has been done to synthesize new
materials with large second-order non-linear optical
features because of their potential use in optical devices
for information processing [1,2]. It is now well known
that molecules possessing extensively conjugated p-elec-
tron systems exhibit large non-linear optical properties.
Organometallic structures are an interesting class of
potentially nonlinear molecular blocks [3,4]. Molecules
with
p
donor-acceptor interactions, like ferro-
cenylethene derivatives, are examples of those struc-
tures, and may serve as monomers for ferrocene
containing polymers, which may offer a variety of
potential applications such as photoactivate semicon-
ductors [5]. Many synthetic methods for ferro-
cenylethene derivatives have been developed. They can
be summarized to three kinds: the first is based on
Wittig reaction of formylferrocene with ylides or (ferro-
cenylmethyl) triphenylphosphonium iodide with alde-
hydes [6–9]; the second is based on Heck reaction of
2
. Results and discussion
The vinylferrocene derivatives could be obtained
from aldehyde and phosphonium salt as shown in
Scheme 1.
1
All products were characterized with H-NMR, MS,
IR and melting points. The results are listed in Table 1
and in the experimental part.
W.M. Horspool reported that triphenylbenzylphos-
phonium halide reacts with formylferrocene in
dimethylsulfoxide catalyzed by sodium hydride under
nitrogen to get 1-ferrocenyl-2-phenylethylene in 70%
yield [8], but according to our operation method in the
Scheme 1.
*
Corresponding author. Fax: 86-931-8611688.
E-mail address: mayx@lzu.edu.cn (Y.-x. Ma).
0
022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00927-X

W.-y. Liu et al. / Journal of Organometallic Chemistry 625 (2001) 128–131
129
5

1
30
W.-y. Liu et al. / Journal of Organometallic Chemistry 625 (2001) 128–131
dry state 95% (Entry 1) and 87% (Entry 2) yields have
been obtained easily. P.L. Pauson obtained trans-1,2-
diferrocenylethylene in 73% yield by the reaction of
formylferrocene with sodium diphenylphosphinite [7],
which we obtained in 91% yield as compared with their
result.
3.2. General procedure for preparation of
ferrocenylethene deri6ati6es
3.2.1. Method A ( for reactions at room temperature)
In a typical experiment, a mixture of formylferrocene
(
la) (1 mmol, 0.214 g), triphenylbenzylphosphonium
chloride (2a) (1.1 mmol, 0.427 g) and NaOH (1.5 mmol,
.06 g) was throughly ground with a pestle in an open
1
From the H-NMR spectra of all the products, the
coupling constants of the two protons on the double
bond manifested the configuration. The characteristic
coupling constant of the Z-isomer is about 12 Hz, and
that of the E-isomer is about 16 Hz. It can be seen
from our results that the main products are E-isomers,
which is in accordance with theoretical calculation [15].
It is notable that 3a and 3b are the same compound,
0
mortar at room temperature (r.t.) under atmosphere.
The reaction mixture was ground for 5 min until the
reaction was complete by TLC monitoring, then ex-
tracted in dichloromethane (20 ml×3). The extracts
were combined and dried with anhydrous NaSO . After
4
filtration, the solvent was removed under vacuum to
give crude product. The residue was chromatographed
on silica gel using petroleum ether as eluent. The
product from the first band was a yellow oily liquid
but their ratio of Z/E is different due to the diversity of
+
the materials used. When FcCHO and PhCH P
2
−
Ph Cl are used as materials, the conversion is in-
3
creased from 87% to 95% and the selectivity forming
E-isomer is also increased (the ratio of Z/E changes
from 1/2 to 1/4) as compared with those obtained from
(
0.055 g), which is Z-ferrocenyl-2-phenylethylene and
that from the second band was yellow crystals (0.219 g),
which is E-ferrocenyl-2-phenylethylene, m.p. 122–
+
−
PhCHO and FcCH P Ph I . It is also found that
2
3
1
24°C (120–122°C in the literature, [13]).
reactions forming 3f and 3g were slower than other
analogs and the yields are rather lower than obtained
from aldol condensation that we had performed before
3.2.2. Method B ( for reactions at 65°C)
[
16]. Maybe, the methylene is stabilized by the carbonyl
In case of heating, aldehyde ylide and NaOH were
mixed and thoroughly ground in an open mortar at r.t.
After keeping the mixture at 65°C in an oven for about
40–50 min., it was ground again for 1–2 min. These
operations were repeated until the reaction was com-
plete by TLC monitoring. The mixture was cooled to
r.t., then extracted and isolated as in method A.
adjacent to it and then has a lower reactivity.
It is obvious, that the solvent-free Wittig reaction not
only is a fast, mild, efficient and simple method to
prepare vinylferrocene derivatives, but also is an effec-
tive way to obtain the E-products.
3
.2.3. 3a, 3b: 1-ferrocenyl-2-phenylethylene
3. Experimental
1
(
Z)-isomer, H-NMR (l, ppm): 4.07 (s, 5H, Cp-ring),
4
.26 (s, 2H, Cp-ring), 4.41 (s, 2H, Cp-ring), 6.22–6.58
1
H-NMR spectra were obtained on a FC-80 spec-
(
(
dd, 2H, CꢁC, J=12.5 Hz), 7.31 (s, 5H, Ar); MS m/z
−1
trometer using CDCl as solvent and TMS as an inter-
nal standard. Mass spectra were obtained on a
ZAB-HS mass spectrometer by fast atom bombardment
3
%): 288 (87); IR (KBr, cm ): wCꢁCꢀH=3001, wCꢁC
=
1
620, ꢀCꢁCꢀH=670.
1
(
E)-isomer, H-NMR (l, ppm): 4.17 (s, 5H, Cp-ring),
(
FAB, MASPECII data base). IR spectra were
4
.31 (s, 2H, Cp-ring), 4.78 (s, 2H, Cp-ring), 6.58–7.03
recorded in KBr on a Nicolet 1795X FT-IR spec-
trophotometer. The melting points reported here were
uncorrected.
(
(
1
dd, 2H, CꢁC, J=16.3 Hz), 7.42 (s, 5H, Ar); MS m/z
−1
%): 288 (90); IR (KBr, cm ): wCꢁCꢀH=3005, wCꢁC
627, ꢀCꢁCꢀH=960.
=
FcCHO and p-Fc-C H CHO were prepared by litera-
6
4
ture methods [6,17]. Other aldehydes were commercially
available chemicals.
3.2.4. 3c: 1-ferrocenyl-2-(4-chloro-phenyl)ethylene
1
(
Z)-isomer, H-NMR (l, ppm): 4.16 (s, 5H, Cp-ring),
.32 (s, 2H, Cp-ring), 4.53 (s, 2H, Cp-ring), 6.34–6.70
(dd, 2H, CꢁC, J=12.1 Hz), 7.38 (s, 4H, Ar); MS m/z
4
3.1. Preparation of phosphonium salts
−
1
(
%): 324 (24), 322 (73); IR (KBr, cm ): wCꢁCꢀH=3024,
(
Ferrocenylmethyl)triphenylphosphonium iodide was
w
CꢁC=1620, ꢀCꢁCꢀH=705.
(E)-isomer, H-NMR (l, ppm): 4.24 (s, 5H, Cp-ring),
1
prepared according to reported method [7]. Methyl-
triphenylphosphonium bromide was obtained from
methyl bromide bubbling through a solution of
triphenylphosphine in benzene. Other phosphonium
salts were prepared by K. Friedrich’s method [18].
4.42 (s, 2H, Cp-ring), 4.58 (s, 2H, Cp-ring), 6.46–6.97
(dd, 2H, CꢁC, J=16.4 Hz), 7.32 (s, 4H, Ar); MS m/z
(%): 324 (31), 322 (90); IR (KBr, cm ): wCꢁCꢀH=3020,
−
1
wCꢁC=1625, ꢀCꢁCꢀH=963.

W.-y. Liu et al. / Journal of Organometallic Chemistry 625 (2001) 128–131
131
−
1
3
.2.5. 3d: 1-ferrocenyl-2-(4-bromo-phenyl)ethylene
m/z (%): 364 (87); IR (KBr, cm ) wCꢁCꢀH=2922,
1
(
Z)-isomer, H-NMR (l, ppm): 4.14 (s, 5H, Cp-ring),
w
CꢁC=1650, ꢀCꢁCꢀH=702.
1
4
.20 (s, 2H, Cp-ring), 4.43 (s, 2H, Cp-ring), 6.28–6.54
(E)-isomer, H-NMR (l, ppm): 4.09 (s, 5H, Cp-ring),
(
dd, 2H, CꢁC, J=12.0 Hz), 7.17–7.49 (q, 4H, Ar); MS
4.38 (s, 2H, Cp-ring), 4.71 (s, 2H, Cp-ring), 7.13 (s, 2H,
−
1
m/z (%): 368 (81), 366 (83); IR (KBr, cm ): wCꢁCꢀH
3
=
CꢁC), 7.32–7.59 (m, 5H, Ar); MS m/z (%): 364 (73); IR
−
1
017, wCꢁC=1622, ꢀCꢁCꢀH=711.
(KBr, cm ) wCꢁCꢀH=2922, wCꢁC=1650, ꢀCꢁCꢀH=965.
1
(
E)-isomer, H-NMR (l, ppm): 4.17 (s, 5H, Cp-ring),
4
.34 (s, 2H, Cp-ring), 4.49 (s, 2H, Cp-ring), 6.51–7.02
3.2.11. 3j: 1-ferrocenyl-2-(4-methoxyphenyl)ethylene
(Z)-isomer, H-NMR (l, ppm): 3.64 (s, 3H, OCH )
4.14 (s, 5H, Cp-ring), 4.36 (s, 2H, Cp-ring), 4.53 (s, 2H,
1
(dd, 2H, CꢁC, J=16.4 Hz), 7.23–7.42 (q, 4H, Ar); MS
3
−
1
m/z (%): 368 (87), 366 (84); IR (KBr, cm ): wCꢁCꢀH
=
3
3
4
022, wCꢁC=1625, ꢀCꢁCꢀH=965.
Cp-ring), 6.16–6.51 (dd, 2H, CꢁC, J=11.9 Hz), 6.68–
7
.43 (m, 4H, Ar); MS m/z (%): 318 (100); IR (KBr,
−
1
.2.6. 3e: 1-ferrocenyl-2-(3-nitro-phenyl)ethylene
cm ): wCꢁCꢀH=3019, wCꢁC=1621, ꢀCꢁCꢀH=682.
1
1
(
Z)-isomer, H-NMR (l, ppm): 4.15 (s, 5H, Cp-ring),
(E)-isomer, H-NMR (l, ppm): 3.57 (s, 3H, OCH )
3
.33 (s, 2H, Cp-ring), 4.50 (s, 2H, Cp-ring), 6.44–6.80
4.17 (s, 5H, Cp-ring), 4.32 (s, 2H, Cp-ring), 4.55 (s, 2H,
Cp-ring), 6.60–6.92 (dd, 2H, CꢁC, J=16.0 Hz), 7.13–
7.50 (m, 4H, Ar); MS m/z (%): 318 (31); IR (KBr,
(
dd, 2H, CꢁC, J=11.8 Hz), 7.33–8.08 (m, 4H, Ar); MS
−1
m/z (%): 333 (98); IR (KBr, cm ) wCꢁCꢀH=3079,
−
1
wCꢁC=1629, ꢀCꢁCꢀH=732.
cm ): wCꢁCꢀH=3020, wCꢁC=1617, ꢀCꢁCꢀH=965.
1
(
E)-isomer, H-NMR (l, ppm): 4.18 (s, 5H, Cp-ring),
4
.36 (s, 2H, Cp-ring), 4.52 (s, 2H, Cp-ring), 6.60–7.18
3.2.12. 3k: 1,2-diferrocenylethylene
(E)-isomer, H-NMR (l, ppm): 4.12 (s, 5H, Cp-ring),
4.17 (s, 5H, Cp-ring), 4.31–4.55 (br, 8H, Cp-ring),
1
(dd, 2H, CꢁC, J=16.2 Hz), 7.37–8.29 (m, 4H, Ar); MS
−
1
m/z (%): 333 (29); IR (KBr, cm ) wCꢁCꢀH=3088,
CꢁC=1632, ꢀCꢁCꢀH=961.
w
6.23–6.51 (dd, 2H, CꢁC, J=16.0 Hz); MS m/z (%):
−
1
3
96 (45); IR (KBr, cm ): wCꢁCꢀH=3028, wCꢁC=1629,
3
.2.7. 3f: 1-phenyl-3-ferrocenylprop-2-en-1-one
ꢀCꢁCꢀH=960.
1
H-NMR (l, ppm): 4.20 (s, 5H, Cp-ring), 4.39 (s, 2H,
Cp-ring), 4.60 (s, 2H, Cp-ring), 7.02–7.25 (br, 2H,
CꢁC), 7.81–7.97 (br, 5H, Ar); MS m/z (%): 316 (61);
References
−
1
IR (KBr, cm ): wCꢁO=1656, wCꢁC=1597.
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1] D.F. Eaton, Science 253 (1991) 281.
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[
[
1
H-NMR (l, ppm): 4.12 (s, 5H, Cp-ring), 4.40 (s, 2H,
(
Cp-ring), 4.55 (s, 2H, Cp-ring), 7.25–8.05 (m, 6H, CꢁC
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3
.2.9. 3h: Vinylferrocene
H-NMR (l, ppm): 4.13 (s, 5H, Cp-ring), 4.23 (s, 2H,
1
Cp-ring), 4.38 (s, 2H, Cp-ring), 4.97–5.12 (q, 1H, (Z)-
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3
2
FcCꢁCH, J =10.6 Hz, J=1.6 Hz), 5.23–5.47 (q,
Z
3
3
1
6
H, (E)-FcCꢁCH, J =17.5 Hz, J=1.6 Hz), 6.31–
E
[
3 3
.66 (q, 1H, FcCHꢁC, J =17.5 Hz, J =10.6 Hz),
E
Z
−
1
MS m/z (%): 212 (100); IR (KBr, cm ): wCꢁCꢀH
=
3
3
4
080, wCꢁC=1650.
[
[
[
[
.2.10. 3i: 1-(4-ferrocenylphenyl)-2-phenylethylene
1
(
Z)-isomer, H-NMR (l, ppm): 4.11 (s, 5H, Cp-ring),
.40 (s, 2H, Cp-ring), 4.72 (s, 2H, Cp-ring), 6.34–6.69
(
q, 2H, CꢁC, J=12.3 Hz), 7.11–7.39 (m, 5H, Ar); MS
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