Palladium-catalyzed cross-coupling reaction of a chiral ferrocenyl zinc reagent with aromatic bromides: Application to the design of chiral octupoles for second harmonic generation

Article abstract of DOI:10.1055/s-2003-37355

Palladium catalyzed cross coupling reaction of a chiral ferrocenylzinc reagent with aryl bromides allowed the introduction of a planary chiral ferrocenyl subunit on an aryl fragment. Using this method, new C₃ symmetric chiral architecture bearing organometallic donor-acceptor fragments were assembled starting from a common tris aldehyde precursor. The non- linear optical properties were measured using the Harmonic Light Scattering method and the potentiality for the new chromophores to behave as octupoles is also discussed.

Full text of DOI:10.1055/s-2003-37355

FEATURE ARTICLE
455
Palladium-Catalyzed Cross-Coupling Reaction of a Chiral Ferrocenyl Zinc
Reagent with Aromatic Bromides: Application to the Design of Chiral
Octupoles for Second Harmonic Generation
a
c
b
b
a,1
P
V
alladium-Catalyz
i
e
d
Cr
o
c
t
React
o
a
Chir
r
Z
M
inc Reagent
w
ith Aro
a
matic Brom
m
ides ane, Isabelle Ledoux-Rak, Sandrine Deveau, Joseph Zyss, Olivier Riant*
a
Laboratoire de Catalyse Moléculaire, ICMO, Université Paris-Sud, 91405 Orsay Cedex, France
E-mail: riant@chim.ucl.ac.be
b
Laboratoire de Photonique Quantique et Moléculaire , Ecole Normale Supérieure de Cachan (UMR CNRS 8537) Institut d’Alember,
IFR 121) – 61 avenue du Président Wilson 94235 Cachan Cedex, France
(
Received 7 November 2002; revised 8 January 2003
the β tensor. The major advantages of octupolar com-
pounds are (i) an expected higher probability to produce
crystals with noncentrosymmetric packing (polar donor-
acceptor molecules tend to align in an antiparallel fashion
Abstract: Palladium catalyzed cross coupling reaction of a chiral
ferrocenylzinc reagent with aryl bromides allowed the introduction
of a planary chiral ferrocenyl subunit on an aryl fragment. Using
this method, new C symmetric chiral architecture bearing organo-
3
metallic donor-acceptor fragments were assembled starting from a with head-to-tail dipole alignment), (ii) an improved non-
common tris aldehyde precursor. The non- linear optical properties linearity/transparency trade-off (due to an increased sym-
were measured using the Harmonic Light Scattering method and the
potentiality for the new chromophores to behave as octupoles is also
discussed.
9
metry order as compared to corresponding dipoles ) and
iii) an extension of the dimensionality of the NLO re-
(
sponse, opening the way to design materials with in-
creased NLO isotropy. A growing number of two- and
Key words: planar chirality, asymmetric synthesis, ferrocene, pal-
ladium, non linear optics, octupole, hyperpolarisability
8,9
three-dimensional (2D and 3D) octupolar templates have
appeared in the literature with the development of the Hy-
per Rayleigh Scattering measurement technique. Exam-
ples of octupolar organic molecules that have been
examined for their quadratic NLO response include tri-
10
The search for molecular materials with large second-or-
der nonlinear optical properties (NLO) has attracted in-
creasing interest over the past twenty years due to their
11
amino-trinitrobenzene derivatives, crystal violet cat-
2
potential applications in photonic devices. Among oth-
12
13
14
ion,
trisubstitued amines,
cyanines salts,
ers, the effects mostly studied are second- and third-har-
monic generation (SHG and THG), linear and nonlinear
electrooptic effects (Pockels and Kerr effects), and organ-
ic photorefractive effects. In the perspective of maximiz-
ing the optical non-linearity, organic and metallo-organic
materials have received major attention due to their chem-
15
16
phosphonium salts or triphenylbenzene derivatives. In
the late 1980’s, the field of molecular materials for NLO
was extended to organometallic and coordination com-
17
pounds. This increasing interest is due to (i) the wide
range of metals with different oxidation states and ligands
18
which can give rise to tunable electronic properties, (ii)
3
,4
ical flexibility and fast electronic response. In the case
of one-dimensional (1D) dipolar push/pull substituted
chromophores, for second-order nonlinear optical appli-
cations such as SHG or Pockels effect, the underlying re-
lations between molecular structure and microscopic
optical non-linearity, as well as the macroscopic non-lin-
earity of the crystalline or polymeric bulk material, are
low-lying charge transfer states which can be associated
with large nonlinearities and (iii) the possibility to achieve
non-centrosymmetric structures by coordination of differ-
ent ligands to a metal center using tetrahedral or propeller-
19
shape coordination geometries or by using the planar
20
chirality of metallocenes. There has been considerable
interest in using metallocenes, especially ferrocene deriv-
atives, as donor groups since the pioneering work of
Green and co-workers in 1987 who reported a SHG effi-
2
–7
now reasonably well understood. More recently, atten-
tion has been extended to octupolar molecules symmetry,
which exhibit non-zero quadratic hyperpolarizability β in
spite of the absence of any ground-state dipole moment.
This new concept of octupolar nonlinearities has been re-
ciency 62 times that of the urea standard for the compound
21
(
Z)-1-ferrocenyl-2-(4-nitrophenyl)ethene. Some metal-
lo-organic octupolar molecules were also described like
8
cently proposed by Zyss on the basis of an irreducible
19
bipyridine metal complexes, C2v σ-acetylides com-
tensor decomposition where β is composed of a vector
22
23
plexes and T tin complexe.
d
8
part (dipolar part) and an octupolar component. For mol-
The design of the new chiral octupoles incorporating
chiral ferrocenyl units as donors is depicted in Figure 1.
The general structure of the molecules we wish to explore
can be formally schematized in terms of three one-dimen-
sional (1-D) units assembled in the 1,3,5 position of a ben-
ecules belonging to purely octupolar space groups such as
D , D , T , and D , the vector part β of β is cancelled
3
3h
d
2
J=1
out and only the octupolar contribution βJ=3 contributes to
Synthesis 2003, No. 3, Print: 28 02 03.
Art Id.1437-210X,E;2003,0,03,0455,0467,ftx,en;Z14102SS.pdf.
zene ring. In that case, the overall C symmetry of the
octupole requires the use of enantiopure ferrocene groups.
These molecules are two-dimensional octupoles, as the
3
©
Georg Thieme Verlag Stuttgart · New York
ISSN 0039-7881

4
56
V. Mamane et al.
FEATURE ARTICLE
Biographical Sketches
Victor Mamane was born in
Casablanca (Morocco) in 1974.
He studied Chemistry in Univer-
sité Paris-Sud where he received
his DEA with Prof. H. B. Kagan
in 1998 while working on asym-
metric hydrogenation and his
PhD with Prof. O. Riant in 2001
in the chemistry of chiral fer-
rocenes as a bulding block for
new materials. He is presently a
Postdoctoral Fellow in the group
of Prof. A. Fürstner at the Max-
Planck Institute in Mülheim/
Rhur (Germany).
Isabelle Ledoux was born in
Rome (Italy) in 1957. She gradu-
ated from Ecole Normale
Supérieure (1981) and Ecole Na-
tionale Supérieure des Télécom-
tional d’Etudes des Télécommu-
Supérieure de Cachan. Her cur-
rent research interest is focused
on molecular and supramolecu-
lar engineering of molecules and
materials for photonic applica-
tions.
nications
(Bagneux)
and
Université Paris-Sud. She is cur-
rently appointed as Professor in
the Physics Departement and
Laboratoire de Photonique
munications
(1983),
and
received her PhD in 1988 with
Prof. Joseph Zyss in Centre Na-
Quantique
(LPQM) at Ecole Normale
et
Moléculaire
Sandrine Deveau was born in
been involved in the develop-
ment of an IR camera with Tha-
les since 1999. She spent 6
months at LPQM – ENS Cachan
in 2000 where she performed
Harmonic Light Scattering expe-
riments at 1.9 µm on various oc-
tupolar molecules. In 2001 she
joined Intelsys, a company devo-
ted to computer Science and En-
gineering, where she is currently
working as a test Manager.
1973. She graduated from Uni-
versities Pierre et Marie Curie -
Paris VI (Master Degree) and
Denis Diderot - Paris VII (DESS
on Materials for Optics). She has
Joseph Zyss was born in Neuil-
ly-sur-Seine (France) in 1950.
He graduated from Ecole Poly-
technique in Paris (1969–1971),
Université Paris VI (DEA in Ap-
plied Mathematics, 1972), Ecole
Nationale Supérieure des Tele-
communications in Paris (1972–
(Centre National d’Etudes des
Télecommunications) in 1974
and held various research posi-
tions in the Physics Division of
the Optoelectronics branch of
CNET located in Bagneux. He
moved in 1998 to Ecole Normale
Supérieure in Cachan as a Pro-
fessor and Director of Labora-
toire de Photonique Quantique et
Moléculaire (1997) and Institut
d’Alembert (2002). His main
topics of interest are polymer
based optoelectronics and related
device technology, micron scale
to nanoscale coherent optical
manipulation of molecular sys-
tems and advanced linear and
nonlinear optical instrumenta-
tion and characterization meth-
ods.
1974) and Université Paris VI
(Doctorat d’Etat, Physical Sci-
ences, 1982). He joined CNET
Olivier Riant was born in Bou-
logne Billancourt (France) in
After a post-doctoral stay with
Prof. S. Gibson (née Thomas) in
London, he started his scientific
career in Université Paris-Sud as
a CNRS research associate. At
the beginning of 2000, he moved
to the Université catholique de
Louvain (Belgium) where he was
appointed Professor. His current
research interest lies in various
aspects of organometallic stereo-
chemistry, with a focus toward
applications in asymmetric catal-
ysis.
1
964. After graduating from
Ecole Normale Supérieure de
Saint Cloud-Lyon, he received
his PhD with Prof. H. B. Kagan
in Université Paris-Sud (1992).
Synthesis 2003, No. 3, 455–467 ISSN 0039-7881 © Thieme Stuttgart · New York

FEATURE ARTICLE
Design of Chiral Octupoles for Second Harmonic Generation
457
2
4
conformation depicted in Figure 1 shows cancellation of ferrocenylbenzenes. Although this method usually lead
the vector properties while maintaining a non centrosym- to the regioselective formation of the unsymmetrical 1,2,4
metric arrangement. Due to the free rotation between each isomer, we decided first to check this method, the precur-
Ar–Fc bond, the presence of a true octupole will require sors being easily accessible through known methods. The
some electronic communication between the three 1-D enantiopure α-iodoferrocene aldehyde 2 was accessible
units. This hypothesis implies that for each octupole, the on a large scale from ferrocene aldehyde by the method of
measurement of the SGH efficiency will have to be com- Kagan, the introduction of an alkynyl group was carried
pared to the corresponding 1-D arm. Thus, in our design, out in a two step procedure. Sonogashira coupling of 2
ferrocene was chosen as a donor group and a convergent with TMS acetylene followed by deprotection of the ter-
synthesis was designed starting from a common precur- minal alkyne gave α-ethynyl ferrocene aldehyde 3 as a
sor. The conjugated spacer was chosen as a compromise stable red crystalline solid. Cyclotrimerization was car-
between the ease of introduction of the ferrocenyl group ried out in refluxing dioxane with 10mol% of Co (CO) as
2
8
and the efficiency of the electronic communication be- a catalyst. We found out that reproducible results were ob-
tween the donor and acceptor group inside each 1-D arm. tained when the reaction was stopped at partial conver-
The thermal and photochemical stability had also to be sion. In that case, some degradation in the reaction
considered and the best compromise between those vari- mixture could be avoided and the purification step was fa-
ous parameters was fixed on the choice of a thiophenylvi- cilitated using this procedure. Purification by chromatog-
nyl spacer. Due to the convergent synthetic scheme raphy on silica gel of the crude reaction mixture allows the
devised, a choice of three efficient acceptor groups was recovery of the unreacted starting aldehyde and the isola-
also fixed for diversity on the octupolar structure.
tion of two new products in 14% and 36% yields respec-
tively, which were fully characterized by spectroscopic
methods. As is well known for the cyclotrimerization of
terminal alkynes, the major product formed was the un-
symmetrical 1,2,4 cyclotrimer 4. We were also pleased to
see that the desired symmetric 1,3,5 isomer was also
formed, albeit in a modest yield. It should also be noted
that other catalytic methods known to favor the formation
of the 1,3,5 isomer were also tested with the alkynyl alde-
hyde 2 without success. In our hands, the use of the
As depicted in Scheme 1, the construction of the chiral
ferrocenyl octupoles I start from a common precursor 1 on
which, the conjugated spacers and the acceptor groups
will be sequentially introduced. We then had first to de-
vise a straightforward and efficient synthesis of this chiral
tris-aldehyde 1 on a multigram scale. Different strategies
for the construction of 1,3,5 tris-arylbenzene derivatives
were first checked. Pioneering work in this area per-
formed by Schlögl et al. had been applied to ferrocene.
Acid catalyzed trimerization of acetylferrocene was first
described by this group for the preparation of 1,3,5-tris-
2
6
CpNbCl /Mg catalyst only led to the formation of deg-
4
radation products with alkyne 2. Although the cyclotrim-
erization of alkyne 2 proved to be a straightforward and
elegant method for the preparation of the target tris-alde-
hyde 1, the low regioselectivity of this reaction led us to
look for an alternative method. Among the known meth-
ods for the construction or aryl-aryl bonds, palladium cat-
2
4
ferrocenyl benzene but we discarded this approach as it
was later shown to be non-reproducible by Sasaki and
2
5
Pittman. An elegant alternative also described by Sou-
kup and Schlögl relies on the cobalt(0) catalyzed [2+2+2]
cyclotrimerisation of terminal ferrocenyl alkynes to tris-
ACpFe
CpFe
CHO
A
OHC
FeCp
FeCp
FeCp
OHC
FeCp
1
I
A
conjugated spacer
S
CN
O
N
S
CN
CN
A
Acceptor group
CN
CN
N
Ph
O
CN
CN
Figure 1
Synthesis 2003, No. 3, 455–467 ISSN 0039-7881 © Thieme Stuttgart · New York

4
58
V. Mamane et al.
FEATURE ARTICLE
Scheme 1
Table 1 Palladium- and Nickel-Catalyzed Cross-Coupling of Fer-
rocenyl Zinc Reagent 6 with 1,3,5-Tribromobenzene
alyzed cross-coupling methods are among the most
powerful and best described and should be applicable to
our problem. In particular, the Negishi coupling of aryl-
zinc halides with aromatic electrophiles could easily be
adapted to the method chosen for the asymmetric func-
tionalization of ferrocenyl aldehydes. Furthermore, the
coupling of ferrocenyl zinc chloride with various aromatic
bromide was already described by the group of Iyoda27
and gave satisfactory yields of 1,3,5-tris-ferrocenyl ben-
zene when 1,3,5-tribromobenzene was used as the elec-
trophilic counterpart. Diastereoselective ortholithiation of
the chiral acetal 5 by t-BuLi in diethyl ether was carried
out using the classical procedure and gave the ferroce-
nylzinc intermediate 6 after transmetallation with zinc
chloride (Scheme 2). In optimized conditions, an excess
of 1.2–1.5 equivalents of the zinc reagent 6 was used per
bromide unit along with a 5% molar ratio of a palladium
or nickel catalyst (with respect to the ferrocenyl zinc re-
agent) (Table 1).
Catalysta
Yieldb
Entry
1
2
3
4
PdCl (PPh )
59
54
21
34
46
2
3 2
PdCl (P(o-Tol) )
2
3 2
PdCl
(dppf)
2
Pd(PPh3)4
5
NiCl (PPh )
2
3 2
a
Reactions were carried out using a 5 mol% amount of the indicated
catalyst.
2
8
b
Isolated yield of tris-acetal 7.
An optimum yield of 59% was reached when
PdCl (PPh ) was used as a catalyst and this procedure
2
3 2
was easily scaled up for the multigram preparation of the
tris-acetal 7. Final acid catalyzed deprotection of the ace-
tal group was also carried out with PTSA in di-
Br
CpFe
MeO
O
OMe
O
O
H
H
H
H
O
OMe
OMe
O
1
2
. t-BuLi, Et2O
O
O
O
Br
Br
ZnCl
FeCp
Fe
Fe
. ZnCl2, THF
5 mol % cat.
see text
O
(2S,4S)-5
(2S,4S,SFc)-6
FeCp
O
(RFc,RFc,RFc)-7
CpFe
OHC
MeO
CHO
PTSA
FeCp
CH2Cl2, H2O
95 %
>
OHC
FeCp
(RFc,RFc,RFc)-1
Scheme 2
Synthesis 2003, No. 3, 455–467 ISSN 0039-7881 © Thieme Stuttgart · New York

FEATURE ARTICLE
Design of Chiral Octupoles for Second Harmonic Generation
459
31
chloromethane–water and yielded quantitatively the duced onto the ferrocene ring via a Emmons–Horner re-
target tris-aldehyde 1. We recently showed that this meth- action between ferrocene carboxaldehyde 11 and the
3
2
od was highly efficient for the preparation of various phosphonate 12, the later being synthesized in a two step
enantiopure α-aryl ferrocene carboxaldehyde and provid- procedure starting from commercially available 2-bro-
ed an useful alternate methods to the Suzuki coupling of mothiophene (Scheme 3). When sodium hydride was
2
9
α-iodoferrocene aldehyde with boronic acids. The gen- used in THF in the presence of a catalytic amount of 15-
erality of this methodology was also checked by coupling crown-5, the desired alkene was quantitatively isolated as
the chiral ferrocenylzinc reagent with aromatic electro- a single trans isomer. The presence of the bromine atom
philes bearing up to four bromide units (Figure 2). After on the thiophene ring also allowed various transforma-
final deprotection, three new polyferrocene aldehydes 8– tions, leading to the installation of the acceptor groups.
1
0 bearing C , C , and C symmetry were isolated in fair Bromine–lithium exchange was carried out in THF using
2 3 4
to good overall yield starting from the corresponding po- n-BuLi to give the corresponding thiophenyllithium de-
lybromides. It should be noted at this point that due to the rivative, which could be in turn trapped with various elec-
large variety of transformations available for the formyl trophiles. When the electrophile was DMF, the thiophenyl
group, such symmetrical molecules could be easily used aldehyde 14 was isolated in a 70% yield and further trans-
for the design and synthesis of new chiral ferrocene based formed into the dipole 15 by Knoevenagel condensation
materials and polymers. The C symmetric bis-aldehyde 8 with diethylthio barbituric acid. Another strong electron-
2
was recently used by us for the synthesis of a C symmet- withdrawing group could also be introduced in a straight-
6
ric hexaarylbenzene molecule bearing six chiral electroac- forward manner by reaction of the thiophenyl lithium in-
3
0
33
tive ferrocenyl units.
termediate with tetracyanoethylene (TCNE) in THF.
After chromatographic purification, the second dipole
bearing a tricyanovinylene pendant was isolated in a 66%
yield. A two step procedure was also used for the intro-
The synthesis of the chiral octupoles required also a pre-
liminary study on the non-chiral dipolar ferrocenyl com-
plexes. This study was carried out first for two main
reasons. First, it was necessary to optimize the reactions
conditions for the various steps on a model aldehyde con-
sidering the fact that each reaction should be adapted to
building the corresponding octupole. High yielding reac-
tions had then to be chosen as they would have to be re-
peated three times during the construction of the final
target octupoles. In addition, the physico-chemical mea-
surements will have to be performed not only on the octu-
poles, but also on the corresponding dipoles for
comparison of the efficiency of the design.
duction
of
the
thermally
stable
2-phenyl
3
5
tetracyanobutadiene onto the thiophene ring. The Sono-
gashira coupling with phenyl acetylene was first carried
out using the modified conditions described by Thorand
34
and Krause and the corresponding alkyne was isolated in
5% yield. The last steps leading to the dipole 18 involves
8
the reaction of the alkyne with TCNE in chloroform. All
new dipoles were isolated as strongly colored powders
(
dark green to purple) and fully characterized by standard
spectroscopic methods.
The optimized methods were then adapted to the case of
the tris-aldehyde 1 for the final construction of the target
octupoles 22–24. It turned out that some of the reaction
As already stated, we selected a thiophenylvinyl group as
a conjugated spacer between the ferrocene donor group
and the acceptor groups. This spacer was easily intro-
Figure 2
Synthesis 2003, No. 3, 455–467 ISSN 0039-7881 © Thieme Stuttgart · New York

4
60
V. Mamane et al.
FEATURE ARTICLE
S
O
N
O
S
N
N
N
CHO
O
O
S
S
S
S
Fe
Fe
Fe
Fe
KF, alumina
CH3CN, ∆
7
1
4
15
7 %
1
2
. n-BuLi, THF
. DMF
7
0 %
CN
CN
Br 1. n-BuLi, THF
. TCNE
6 %
CHO
NaH, cat 15-Crown-5
S
P(O)(OEt)2
CN
Fe
Fe
+
Br
2
S
THF, ∆
6
1
2
> 95 %
13
16
1
1
cat PdCl2(PPh3)2
PPh3, CuI
Et3N, THF, rt
8
5 %
Ph
CN
TCNE
S
CN
CN
Ph
NC
Fe
CHCl3, rt
5
3 %
1
8
1
7
Scheme 3
had to be re-optimized when applied to the tris-aldehyde unfortunately unable to grow single crystals for X-ray
and the corresponding tris-bromide 19. When the tris-al- studies.
1
dehyde was condensed with the phosphonate reagent 12,
using two equivalent of the phosphonate per formyl
group, H NMR examination of the crude reaction mix-
Linear and Nonlinear Optical Properties
1
ture indicated the presence of minor geometrical isomers. The quadratic second-order hyperpolarizabilities β of
However, the all trans isomer 19 was isolated in 76% molecules 22–24 and of their corresponding 1-D arms 15,
yield by performing an isomerization step (cat. iodine, 16, and 18 are reported in Table 2. HRS measurements
CH Cl , reflux) prior to the chromatographic purification. had to be performed at 1.91 µm, the corresponding second
2
2
1
In that case, the H NMR of the purified triene displayed harmonic wavelength at 955 nm being safely removed far
sharp peaks indicating the presence of a single isomer. from the visible charge transfer absorption band of the
The preparation of the two octupoles 22 and 23 could be molecules, so as to avoid systematic experimental errors
carried out under similar conditions used for the corre- that would otherwise arise from linear absorption of har-
sponding dipoles and were isolated in fair to good yields. monic photons or from two-photon fluorescence phenom-
In the case of 23, the procedure used for the dipole had to ena.
be adapted for complete conversion of the reacting groups
of 19 and 21. In the first step, a 79% yield was reached for
Linear UV-visible absorption spectra display two main
transitions. One is located in the blue-green spectral
the Sonogashira coupling when 3 equivalent of phenyl
range, and depends only weakly on the nature of the ac-
acetylene and 20 mol% of palladium were used per bro-
ceptor group; moreover, its λmax value is exactly the same
mide unit. Optimum yield was also obtained for the con-
for the octupolar molecules and their respective 1-D arms.
version of 21 into the octupole 24 by using a very large
This band can be ascribed to the ferrocenyl moiety, the
corresponding electronic transition remaining located on
the ferrocene site. The second band, located in the red part
excess of TCNE and carrying out the reaction in refluxing
chloroform (Scheme 4). The three octupoles 22–24 could
then be isolated in reasonable overall yield from the start-
of the visible range, strongly depends on the acceptor
ing tris-aldehyde 1 and were fully characterized. They
group and corresponds to an intramolecular charge trans-
fer (ICT) between the ferrocenyl donor part and the accep-
tor groups, involving all delocalized π-electrons of the
conjugated path. As expected, ICT λmax values of octupo-
were isolated as strongly colored microcrystalline powder
and could be stored in air for prolonged time without no-
ticeable decomposition. They also proved to be fairly sol-
uble in most common polar organic solvents but we were
lar molecules are slightly shifted to the blue region with
9
respect to their 1-D equivalent subunits. This may be ex-
Synthesis 2003, No. 3, 455–467 ISSN 0039-7881 © Thieme Stuttgart · New York

FEATURE ARTICLE
Design of Chiral Octupoles for Second Harmonic Generation
461
Scheme 4 A: i 12 (6 equiv), NaH, 10 mol% 15-crown-5, 25 °C, 4 h; ii cat I , CH Cl , 50 °C, hν, 15 h (76%). B i n-BuLi (3 equiv), THF, –
2
2
2
7
8 °C→> 25 °C; ii DMF, –78 °C→>25 °C then 1 N HCl (96%). C: Diethylthio barbituric acid (15 equiv), KF-alumina, CH CN, reflux, 1.5 h
3
(79%). D: i n-BuLi (3 equiv), THF, –78 °C→> 25 °C ii TCNE (10 equiv), –78 °C→> r.t. (82%). E: phenylacetylene (9 equiv), cat
PdCl (CH CN) (20 mol% per Br), Ph P (40 mol% per Br), CuI (20 mol% per Br), i-Pr NH, 70 °C, 3 h (79%). E: TCNE (9 equiv), CHCl ,
2
3
2
3
2
3
60 °C, 1.5 h (61%).
plained by the higher symmetry degree of octupolar enti- quency-independent static β(0) values of the molecules
ties, restricting the number of allowed electronic reported in Table 2.
transitions between the ground state and higher energy
levels.
As λmax values differ from each other for molecules re-
ported in Table 2, the comparison of β values is relevant
only after corrections of wavelength dispersion factors.
Equation 1
As the transition around 490 nm is strongly localized on
According to a preliminary, naive analysis of these NLO
data, experimental β(0) values of octupoles 22–24 are at
least 3 times higher than those of their dipolar 15, 16, and
the centrosymmetric ferrocenyl unit, resonances with the
corresponding level do not contribute to the β value. Only
the ICT level in the red spectral domain has then to be
considered, so that all β values reported here can be de-
scribed in terms of a 2-level frequency dispersion model
1
8 counterparts, respectively. Clearly the octupolar orga-
nization of the three 1-D arms as grafted on the 1,3,5 sub-
stitution sites of the benzene ring is not detrimental, in
terms of the β/V ratio (V being the molecular volume) rel-
3
6
(
1
Equation 1), where ω is the incident IR frequency at
.91 m, ω is the frequency of the transition towards the
0
3
7
evant for material applications, as compared to a perfect
dipolar parallel arrangement of these subunits. In that re-
ICT state. In the following, we will discuss only the fre-
Table 2 Maximum Absorption Wavelengths λmax, and Quadratic Hyperpolarizabilities β of Octupolar Species 22–24 and of their 1-D Coun-
terparts 15, 16, and 18a
Molecule
λmax (nm)
β(1.91 m)
β(0)
15
16
18
22
23
24
488, 616
504, 724
478, 663
488, 608
350
508,712
500
478, 658
500
120
63
–
140
51
–
180
82
–
187
190
231
β(0)add
189
153
246
a
β Values are given in 10–30 esu. ICT λmax values are indicated in bold.
Synthesis 2003, No. 3, 455–467 ISSN 0039-7881 © Thieme Stuttgart · New York

4
62
V. Mamane et al.
FEATURE ARTICLE
spect, the availability of octupolar units offers some spe- NH
Cl (50 mL) and extracted with Et
O (2 × 100 mL). The organic
4
2
phase was dried over MgSO , the solvent evaporated, and the resi-
cific additional advantages in terms of an extended
dimensionality of the β tensor as compared to dipolar
structures, resulting in an improved molecular and mate-
rial isotropy, a highly desired property in devices for opti-
cal communications.
4
due was purified by column chromatography on silica gel (toluene–
Et O, 2:1). The product was isolated as a light orange solid (3 g,
2
2
3
2
.94 mmol, 59%); mp 70 °C; [α]D –137 (c 1, CHCl3).
1
H NMR (CDCl , 250 MHz): δ = 1.53 (m, 3 H, CH ), 1.82 (m, 3 H,
3
2
CH ), 3.24 (s, 9 H, CH ), 3.38 (m, 6 H, 3 × CH O), 3.99 (m, 6 H, 3
2
3
2
However, this crude approach cannot be considered as a × CH O), 4.16 (m, 21 H, Cp, Cpsubst, CHO), 4.48 (m, 3 H, Cpsubst.),
2
rigorous additive model. As experimental β values of oc- 4.61 (m, 3 H, Cpsubst.), 5.57 (s, 3 H, 3 × OCHO), 7.70 (s, 3 H, aro-
2
matics).
tupoles refer to <square root (β )>, they cannot be inter-
2
13
preted as a simple addition of the <square root (β )> of
their 1-D counterparts. In fact, as developed earlier, di-
polar and octupolar contributions to the β tensor must be Electrospray MS: m/z (%) = 1043.0 (100) [M + Na ], 1021.0 (3)
C NMR (CDCl , 63 MHz): δ = 28.2, 59.25, 67.05, 67.3, 67.85,
3
3
8
6
9.35, 70.35, 75.25, 76.1, 84.6, 87.4 99.65, 128.5, 137.35.
+
+
separately added, i.e.
[M ], 653.0 (12), 465.1 (19).
βJ=1total = Σ β′J=1 and βJ=3total = Σ β′J=3 where Σ refers to the
tensorial sum, over the three 1-D arms, of the β′J=1 (resp.
β′J=3) dipolar (resp. octupolar) parts of their β′ tensor. H O (30 mL) and PTSA (29.4 mmol, 5.6 g) were added and the mix-
1
,3,5-Tri[(R)- -formylferrocenyl]benzene (1)
Trisacetal 7 (2.94 mmol, 3 g) was dissolved in CH Cl (70 mL).
2
2
2
Therefore, if we assume an additive model and a purely ture was stirred vigorously for 2 h at r.t. A sat. solution of NaHCO
3
(
70 mL) was added and the organic phase was separated, dried over
octupolar geometry for molecules 22–24, their β values
would be the sum of β′J=3 contributions only. As a signif-
icant, if not dominant β′J=1 term contributes to the β′ ten-
sor of each arm, β′J=3 is necessarily smaller than β′.
Therefore, a purely additive model would mean that
β(0)add < 3β′(0) for any octupolar molecule reported in
Table 2. As experimental β(0) values of compounds 22–
MgSO4 and concentrated. After filtration on silica gel (Et O–
2
CH Cl , 1:1) and recrystallization from Et O, the product was iso-
2
2
2
lated as an orange powder (2.1 g, 2.94 mmol, 100%); mp decomp at
23
2
50 °C; [α]D +180 (c 0.05, CHCl3).
–
1
IR (KBr, CHCl ): 1672 cm (CO).
3
1
H NMR (CDCl , 250 MHz): δ = 4.33 (s, 15 H, Cp), 4.74 (m, 3 H,
3
Cpsubst.), 4.86 (m, 3 H, Cpsubst.), 5.00 (m, 3 H, Cpsubst.), 7.64 (s, 3 H,
aromatics), 10.27 (s, 3 H, 3 × CHO).
2
4 are at least equal, if not higher than 3β′, this result is a
clear signature of a significant electronic constructive in-
teraction between the three 1-D arms through the benzene
ring.
1
3
C NMR (CDCl , 63 MHz): δ = 69.75, 71.2, 72.25, 75.65, 91.5,
3
1
29.95, 136.35, 192.5.
HRMS: m/z calcd for C H Fe O , 714.0243; found, 714.0245.
3
9
30
3
3
Mps were determined on a Reichert apparatus. IR spectra were re-
corded using a Perkin-Elmer FTIR 1600 spectrometer and are re-
(
(
R ,RFc′)-1,2-Bis[4′( -formylferrocenyl)-1′-phenyl]acetylene
8)
Fc
–
1
ported in wave numbers (cm ). UV-VIS spectra were recorded on
a Kontron spectrometer. Optical rotations were measured on a Per-
A solution of acetal 5 (10 mmol, 3.16 g) in dry degassed Et O (40
mL) was treated with a pentane solution of t-BuLi (1.6 M, 20 mmol,
1
stirred for 1 h. To the orange suspension at –78 °C was added a
freshly prepared solution of anhyd ZnCl (0.5 M in THF, 11 mmol,
2
2
1
13
kin-Elmer 241 polarimeter. H and C NMR spectra were recorded
on Brucker AC 200 (200 MHz and 50 MHz) and AC 250 (250 MHz
and 63 MHz) machines. Chemical shifts (δ) are reported in ppm and
coupling constants (J) in Hz. As the internal reference, the solvent
4 mL) at –78 °C for 10 min. The reaction was warmed to r.t. and
2
2 mL). The solution was warmed to r.t. and stirred for 1 h. To the
1
13
signal [ H: δ (CDCl ) = 7.27, C: δ (CDCl ) = 77.0] was used. EI
3
3
mixture was added PdCl (PPh ) (0.5 mmol, 351 mg, 5%) followed
2
3 2
mass spectra (70 eV) were measured on a Riberg Mag R10-10.
HRMS and Electrospray mass spectra were determined using a
Finnigan MAT-95-S apparatus.
by bis(4-bromophenyl)acetylene (4.5 mmol, 1.512 g). After stirring
at r.t. overnight the mixture was treated with a sat. solution of
NH Cl (30 mL) and extracted with Et O (2 × 60 mL). The organic
4
2
phase was dried over MgSO , the solvent evaporated, and the resi-
THF and Et O were distilled from Na/benzophenone, DMF and
4
2
due was purified by column chromatography on silica gel (Et O–cy-
CH CN from CaH and CH Cl from P O . All air or moisture sen-
2
3
2,
2
2
2
5
clohexane, 2:1). The diacetal product was isolated as a light orange
sitive reactions were carried out under Ar using standard Schleck
tube/vacuum line apparatus. Flash column chromatography was
performed employing 60 A C C 35–70 µm silica gel.
2
3
s
o
l
i
d
(
2
.
6
g
,
3
.
2
2
m
m
o
l
,
5
9
%
)
;
m
p
8
8
°
C
;
[
α
]
–
4
7
1
(
c
1
,
C
H
C
l
)
.
D
3
1
H NMR (CDCl , 250 MHz): δ = 1.47 (2 H, m, CH ), 1.81 (2 H, m,
3
2
CH ), 3.36 (6 H, s, 2 × CH ), 3.46 (4 H, m, 2 × CH O), 3.96 (2 H,
Chiral acetal 1 was prepared from commercially available ferrocene
2
3
2
2
8
m, CH O), 4.09 (10 H, s, Cp), 4.29 (2 H, m, Cpsubst.), 4.56 (2 H, m,
aldehyde using the literature procedure. (R)-2-ethynylferrocene
2
2
9
Cpsubst.), 4.58 (2 H, m, Cpsubst.), 5.46 (2 H, s, OCHO), 7.46 (4 H, d,
J = 8.1 Hz, aromatics), 7.65 (4 H, d, J = 8.1 Hz, aromatics).
carboxaldehyde 3 was prepared according to a known procedure.
1
,3,5-Tri [(2′S,4′S,S )-4′-methoxymethyl-2′-ferrocen- -yl-1′,3′-
13
Fc
C NMR (CDCl , 63 MHz): δ = 26.9, 27.8, 59.3, 67.0, 67.75, 67.9,
3
dioxane]benzene (7)
A solution of acetal 5 (17.5 mmol, 5.53 g) in dry degassed Et O (50
mL) was treated with a pentane solution of t-BuLi (1.6 M, 20 mmol,
1
7
0.55, 71.05, 75.45, 76.1, 83.0, 85.95, 89.75, 99.9, 120.9, 129.0,
2
131.1, 139.0.
HRMS: m/z calcd for C H Fe O , 806.1993; found, 806.2003.
4
6
46
2
6
4 mL) at –78 °C for 10 min. The reaction was warmed to r.t. and
stirred for 1 h. To the orange suspension at –78 °C, was added a
Diacetal (3.22 mmol, 2.6 g) was dissolved in CH Cl (70 mL). H O
2 2 2
freshly prepared solution of anhyd ZnCl (0.5 M in THF, 20 mmol,
(30 mL) and PTSA (32.2 mmol, 6.2 g) were added and the mixture
2
4
0 mL). The orange solution was warmed to r.t. and stirred for 1 h.
was stirred vigorously for 2 h at r.t. A sat. solution of NaHCO (50
3
To the mixture was added PdCl (PPh ) (0.875 mmol, 614 mg, 5%)
mL) was added and the organic phase was separated, dried over
2
3 2
followed by 1,3,5 tribromobenzene (5 mmol, 1.575 g). After stirring
at r.t. overnight the mixture was treated with a sat. solution of
MgSO4 and concentrated. After filtration on silica gel (Et O–
2
CH Cl , 1:1) and recrystallization from Et O, the product 8 was iso-
2
2
2
Synthesis 2003, No. 3, 455–467 ISSN 0039-7881 © Thieme Stuttgart · New York

FEATURE ARTICLE
Design of Chiral Octupoles for Second Harmonic Generation
463
lated as an orange solid (1.85 g., 3.2 mmol, 95%); mp 108 °C;
α] +341 (c 0.088, CHCl ).
This product was dissolved in CH Cl (14 mL). H O (6 mL), PTSA
2
2
2
[
(4.7 mmol, 893 mg) were added and the mixture was stirred at r.t.
for 2 h. A sat. solution of NaHCO (30 mL) was added and the or-
D
3
–
1
3
IR (KBr, CHCl ): 1662 cm (CO).
3
ganic phase was recovered, dried over MgSO and concentrated.
4
1
H NMR (CDCl , 200 MHz): δ = 4.24 (10 H, s, Cp); 4.73 (2 H, m,
3
After filtration over silica (Et O–CH Cl , 1:1) and recrystallization
2
2
2
Cpsubst.); 4.86 (2 H, m, Cpsubst.); 5.00 (2 H, m, Cpsubst.); 7.50 (8 H, s,
aromatics); 10.18 (2 H, s, 2 × CHO).
from Et O, the desired product was isolated as a red solid (505 mg,
2
23
0
.437 mmol, 100%); mp 110 °C; [α]D –722 (c 0.018, CHCl3).
1
3
C NMR (CDCl , 63 MHz): δ = 69.2, 71.25, 72.3, 89.95, 91.4,
–1
3
IR (KBr, CHCl ): 1661 cm (CO).
3
1
22.0, 129.5, 131.45, 136.55, 192.7.
1
H NMR (CDCl , 250 MHz): δ = 2.41 (s, 9 H, CH ), 4.30 (s, 5 H,
3
3
HRMS: m/z calcd for C H Fe O , 602.0632; found, 602.0631.
3
6
26
2
2
Cp), 4.73 (t, 3 H, J = 2.5 Hz, Cpsubst.), 4.89 (br s, 3 H, Cpsubst.), 5.00
br s, 3 H, Cpsubst.), 6.60 (d, 3 H, J = 16.3 Hz, alkene), 6.87 (d, 3 H,
J = 3.6 Hz, thiophene), 6.97 (d, 3 H, J = 16.3 Hz, alkene), 7.03 (d,
(
1
,3,5-Trimethyl-2,4,6-tri(methylenetriphenylphosphoniumbro-
mide)benzene
3
H, J = 3.6 Hz, thiophene), 10.34 (s, 3 H, 3 × CHO).
A mixture of 1,3,5-trisbromomethyl-2,4,6-trimethylbenzene (Ald-
rich, 7.5 mmol, 3 g) and PPh (25 mmol, 6.55 g) in CH CN (10 mL)
1
3
C NMR (CDCl , 63 MHz): δ = 19.2, 69.3, 71.55, 72.3, 74.3, 84.1,
3
3
3
1
26.1, 127.3, 127.4, 127.55, 133.3, 135.35, 138.15, 142.3, 192.7.
was heated at reflux under argon for 24 h. CH CN was evaporated
3
and the residue was disolved in CH Cl (50 mL). Addition of Et O
FABMS: m/z (%) = 1080.1 (75) [M+].
2
2
2
(300 ml) resulted in the formation of a gum which was stirred for 1
h to give a white solid which was filtered and washed with Et O (8.9
5,10,15,20-Tetrakis(4-bromophenyl)porphyrin
2
g, 7.5 mmol, 100%); mp > 230 °C.
A 500 mL flask was charged with a solution of pyrrole (1.4 mL, 20
mmol) and p-bromobenzaldehyde (3.7 g, 20 mmol) in nitrobenzene
1
H NMR (CDCl , 200 MHz): δ = 2.09 (s, 9 H, CH ), 4.93 (d, 6 H,
3
3
(100 mL) and HOAc (150 mL). The dark solution was placed in a
JH-P = 13 Hz, CH ), 7.35–7.55 (m, 18 H, phenyl), 7.60–7.80 (m, 27
2
preheated bath at 120 °C and stirred at this temperature for 1 h. Af-
ter cooling to r.t., the precipitate was filtered and washed with
MeOH (3 × 50 mL) . The product was isolated as light violet crys-
tals (1.5 g, 32%); mp 170 °C.
H, phenyl).
1
3
C NMR (CDCl , 63 MHz): δ = 19.95, 28.5 (J = 46.2 Hz),
3
C-P
1
16.65, 118.0, 126.85.
3
1
P NMR (CDCl , 101 MHz): δ = 18.7.
1
3
H NMR (CDCl , 250 MHz): δ = –2.90 (2 H, s, NH), 7.87 (8 H, d,
3
J = 8.3 Hz, aromatics), 8.04 (8 H, d, J = 8.3 Hz, aromatics), 8.82 (8
H, s, Hpyrrol).
HRMS Electrospray: m/z calcd for C H P , 944.3830; found,
6
6
59 3
9
44.3830.
1
3
C NMR (CDCl , 63 MHz): δ = 118.95, 122.6, 123.45, 129.25,
3
1
,3,5-Trimethyl-2,4,6-tri(2′-bromo-5′-trans-vinylthiophene)-
1
29.95, 134.55, 135.8, 140.8.
benzene
HRMS: m/z calcd for C H Br N , 925.8891; found, 925.8891.
4
4
26
4
4
Trisphosphonium salt (3 mmol, 3.55 g) and t-BuOK (10 mmol, 1.12
g) were placed in a dry Schlenk tube under argon. Anhyd DMF (20
mL) was added and the mixture was stirred vigorously for 15 min
to give a red solution (exothermic). 5-Bromo-2-formylthiophene (9
mmol, 1.06 mL) was added and the solution was heated at 120 °C
for 24 h. The mixture was hydrolyzed and extracted with CH Cl
5
,10,15,20-Tetrakis(4-bromophenyl)porphyrin Nickel (II)
To a solution of porphyrin (465 mg, 0.5 mmol), CHCl (25 mL), and
3
HOAc (25 mL) was added Ni(OAc) ⋅4H O (200 mg, 0.8 mmol). Af-
2
2
ter stirring the solution at 120 °C for 1 h, the precipitate was filtered
and washed with MeOH (3 × 10 mL). The product was isolated as a
purple solid (460 mg, 93%); mp 230 °C.
1
2
2
(60 mL). After a standard work-up, the product was purified by
flash chromatography on silica gel (CH Cl ) and recrystallized from
2
2
Et O–pentane. The product was isolated as yellow crystals (650 mg,
H NMR (CDCl , 250 MHz): δ = 7.80 and 7.85 (16 H, AB system,
2
3
0
.956 mmol, 32%); mp 78 °C.
J = 8.4 Hz, aromatics), 8.71 (8 H, s, Hpyrrol).
1
13
H NMR (CDCl , 200 MHz): δ = 2.28 (s, 9 H, CH ), 6.47 (d, 3 H,
C NMR (CDCl , 63 MHz): δ = 120.1, 122.6, 130.2, 132.25, 135.0,
3
3
3
J = 16.4 Hz, alkene), 6.72 (d, 3 H, J = 3.8 Hz, thiophene), 6.83 (d,
139.6, 142.55.
3
H, J = 16.4 Hz, alkene), 6.94 (d, 3 H, J = 3.8 Hz, thiophene).
FABMS: m/z (%) = 983.8 (100) [M+].
1
3
C NMR (CDCl , 63 MHz): δ = 19.05, 111.0, 125.85, 127.1,
3
1
27.85, 130.3, 133.3, 135.05, 144.2.
5,10,15,20-Tetrakis[4-(2′S,4′S,R )-4′-methoxymethyl-2′-ferro-
Fc
+
+
cen- -yl-1′,3′-dioxane]porphyrin Nickel(II) and 5,10,15,20-Tet-
rakis[4- -formylferrocenyl)]porphyrin Nickel(II) (10)
MS (70 eV): m/z (%) = 682 (100) [M ], 602 (8) [M – Br].
A solution of acetal 5 (1.52 mmol, 480 mg) in dry degassed Et O
2
(
SFc,SFc′,SFc′′)-1,3,5-Trimethyl-2,4,6-tri[ -(5′-trans-vinylthio-
(10 mL) was treated with a pentane solution of t-BuLi (1.6 M, 1.67
phenyl)-2′-formylferrocenyl]benzene (9)
A solution of acetal 5 (4.5 mmol, 1.43 g) in dry degassed Et O (50
mL) was treated with a pentane solution of t-BuLi (1.6 M, 7 mmol,
5
stirred for 1 h. To the orange suspension at –78 °C was added a
freshly prepared solution of anhyd ZnCl (0.5 M in THF, 7 mmol,
1
mmol, 1.1 mL) at –78 °C for 10 min. The reaction was warmed to
r.t. and stirred for 1 h. To the orange suspension at –78 °C was add-
2
ed a freshly prepared solution of anhyd ZnCl (0.5 M in THF, 1.67
2
mL) at –78 °C for 10 min. The reaction was warmed to r.t. and
mmol, 3.34 mL). The solution was warmed to r.t. and stirred for 1
h. To the mixture was added PdCl (PPh ) (0.076 mmol, 53 mg,
2
3 2
2
5
%) followed by 5,10,15,20-tetrakis-(4-bromophenyl)-porphyrine
4 mL). The solution was warmed to r.t. and stirred for 1 h. To the
nickel(II) (0.253 mmol, 250 mg). After stirrring at r.t. overnight the
mixture was added PdCl (PPh ) (0.225 mmol, 106 mg, 5%) fol-
2
3 2
mixture was treated with a sat. solution of NH Cl (10 mL) and ex-
4
lowed by trisbromothiophene (1 mmol, 681 mg). After being stirred
at r.t. overnight the mixture was treated with a sat. solution of
NH Cl (20 mL) and extracted with Et O (2 × 50 mL). The organic
phase was dried over MgSO , the solvent evaporated, and the resi-
due was purified by column chromatography on silica gel (toluene–
tracted with Et O (2 × 50 mL). The organic phase was dried over
2
MgSO , the solvent evaporated, and the residue was purified by col-
4
4
2
umn chromatography on silica gel (CH Cl –cyclohexane–Et O,
2
2
2
4
2
:1:1). The product was isolated as a purple powder (360 mg, 0.187
2
3
mmol, 74%); mp 188 °C; [α]D –113 (c 0.106, CHCl3).
Et O, 3:1). The product was isolated as a red powder (650 mg, 0.437
2
mmol, 47%).
Synthesis 2003, No. 3, 455–467 ISSN 0039-7881 © Thieme Stuttgart · New York

4
64
V. Mamane et al.
FEATURE ARTICLE
1
13
H NMR (CDCl , 250 MHz): δ = 1.50 (m, 4 H, CH ), 1.89 (m, 4 H,
C NMR (CDCl , 63 MHz): δ = 69.25, 82.45, 109.5, 118.6, 124.35,
3
2
3
CH ), 3.32 (s, 9 H, CH ), 3.48 (m, 2 H, CH O), 4.12 (m, 8 H, 4 ×
127.55, 130.35, 145.2.
2
3
2
CH O), 4.25 (s, 20 H, Cp), 4.38 (t, 4 H, J = 2.4 Hz, Cpsubst.), 4.40 (m,
HRMS: m/z calcd for C H 79BrFeS, 371.9271; found, 371.9274.
2
1
6
13
4
H, 4 × CHO), 4.68 and 4.69 (2 s, 8 H, Cpsubst.), 5.76 (s, 4 H, 4 ×
OCHO), 7.97 (s, 16 H, aromatics), 8.90 (s, 8 H, pyrrole).
5
-(trans)-Ferrocenylvinylthiophen-2-yl-carbaldehyde (14)
1
3
C NMR (CDCl , 63 MHz): δ = 27.85, 59.25, 67.1, 67.8, 70.65,
To a solution of bromothiophene 13 (0.67 mmol, 250 mg) in THF
(10 mL) at –78 °C was added slowly a solution of BuLi (1.6 M in
hexane, 1.2 equiv, 0.8 mmol, 500 µL) and the mixture was stirred at
–78 °C for 15 min. DMF (3.35 mmol, 240 µL) was added at –78 °C
and the reaction was warmed to r.t. and stirred for 1 h. After hydrol-
ysis, the mixture was extracted with CH Cl (30 mL), dried over
MgSO and concentrated. The residue was purified by flash chro-
matography on silica gel (toluene–Et O, 8:1) to give the aldehyde as
a red powder (150 mg, 0.466 mmol, 70%); mp 136 °C.
3
7
1
1.25, 75.5, 76.05, 83.2, 86.2, 100.1, 119.05, 127.4, 132.25, 133.55,
38.2, 138.6, 142.7.
FABMS: m/z (%) = 1927.9 (50) [M+].
The tetraacetal (0.083 mmol, 160 mg) was dissolved in CH Cl (20
2
2
2
2
mL). H O (7 mL) and PTSA (3.32 mmol, 630 mg) were added and
2
4
the mixture was stirred at r.t. for 2 h. A sat. solution of NaHCO (10
mL) was added and the organic phase was separated, dried over
3
2
MgSO and concentrated. After filtration over silica gel (Et O–
4
2
–1
IR (KBr, CCl ): 1670 cm (CO).
4
CH Cl , 1:1) and recrystallization from MeOH, the desired porphy-
2
2
1
rin was isolated as a violet solid (120 mg, 0.79 mmol, 95%);
H NMR (CDCl , 200 MHz): δ = 4.16 (s, 5 H, Cp), 4.36 (m, 2 H,
3
mp 227 °C; [α]D23 +118 (c 0.128, CHCl3).
Cpsubst.), 4.47 (m, 2 H, Cpsubst.), 6.78 (d, 1 H, J = 15.9 Hz, alkene),
6.97 (d, 1 H, J = 15.9 Hz, alkene), 7.01 (d, 1 H, J = 3.9 Hz,
thiophene), 7.61 (d, 1 H, J = 3.9 Hz, thiophene).
13
–
1
IR (KBr, CHCl ): 1666 cm (CO).
3
1
H NMR (CDCl , 250 MHz): δ = 4.39 (s, 20 H, Cp), 4.84 (t, 4 H,
3
C NMR (CDCl , 63 MHz): δ = 67.4, 69.45, 70.05, 81.35, 118.0,
3
J = 2.4 Hz, Cpsubst.), 5.08 (br s, 4 H, Cpsubst.), 5.11 (d, 4 H, J = 2.2
Hz, Cpsubst.), 7.84 (d, 8 H, J = 8 Hz, aromatics), 8.02 (d, 8 H, J = 8
Hz, aromatics), 8.87 (s, 8 H, pyrrole), 10.45 (s, 4 H, 4 × CHO).
1
24.85, 132.85, 137.55, 140.35, 153.45, 182.4.
HRMS: m/z calcd for C H FeSO, 322.0115; found, 322.0115.
1
7
14
1
3
C NMR (CDCl , 63 MHz): δ = 69.15, 71.4, 72.4, 75.5, 76.5, 92.0,
3
5
-[5′-(trans)-Ferrocenylvinyl-thiophen-2′-yl-methylene]-1,3-di-
1
18.6, 128.2, 132.35, 133.8, 135.85, 139.5, 142.6, 193.2.
ethyl-2-thioxo-dihydro-pyrimidine-4,6-dione (15)
The aldehyde 14 (0.31 mmol, 100 mg), diethyl thiobarbituric acid
FABMS: m/z (%) = 1519.0 (100) [M+].
(
0.4 mmol, 80 mg) and KF on alumina (155 mg) were placed in a
Diethyl [(5-Bromothiophe-2-yl)methyl]phosphonate (12)
A 250 mL flask fitted with a reflux condenser was charged with 2-
bromothiophene (9.7 mL, 100 mmol), paraformaldehyde (3.3 g, 110
mmol) and HOAc (50 mL). HBr in HOAc (20 mL, 37%) was added
and the solution was heated in a well ventilated fume cupboard at
dry Schlenk tube. CH CN (10 mL) was added and the mixture was
heated at 80 °C for 1 h. After evaporation of the solvent in vacuo,
the residue was dissolved in CH Cl (10 mL) and filtered on celite.
Filtration on silica gel (Et O) and recrystallization from MeOH
gave a black powder (120 mg, 0.238 mmol, 77%); mp 245 °C.
3
2
2
2
5
0 °C for 3 h. After cooling the solution, the reaction mixture was
–
1
IR (KBr, CCl ): 1691 cm (CO).
4
extracted with CH Cl (200 mL) and washed with cold H O (50
2
2
2
1
mL). After standard work up, 20 g of a brown oil were isolated and
mixed with triethylphosphite (14 mL, 80 mmol). The viscous solu-
tion was stirred at 150 °C overnight. Evaporation of the excess of
triethylphosphite yielded 25 g of a dark oil. Chromatographic sepa-
H NMR (CDCl , 250 MHz): δ = 1.33 (2 t, 6 H, J = 7 Hz, 2 × CH ),
3
3
4.17 (s, 5 H, Cp), 4.45 (AA′XX′ system, 2 H, J = 1.8 Hz, Cpsubst.),
4.52 (AA′XX′ system, 2 H, J = 1.8 Hz, Cpsubst), 4.58 (m, 4 H, 2 ×
CH ), 6.83 (d, 1 H, J = 15.9 Hz, alkene), 7.13 (d, 1 H, J = 4.2 Hz,
2
ration on silica gel was achieved using 5 g portions of the oil (Et O
thiophene), 7.28 (d, 1 H, J = 15.9 Hz, alkene), 7.75 (d, 1 H, J = 4.2
2
→
Et O–MeOH, 99:1). The product was isolated as a red oil (15 g,
Hz, thiophene), 8.60 (s, 1 H, CH).
2
4
8% overall).
13
C NMR (CDCl , 63 MHz): δ = 12.4, 12.55, 43.1, 43.95, 67.85,
3
1
H NMR (CDCl , 250 MHz) : δ = 1.19 (6 H, t, J = 7.1 Hz, 2 × CH ),
69.7, 70.8, 81.15, 109.9, 118.3, 126.05, 135.35, 136.2, 147.9, 149.1,
161.35.
3
3
3
.17 (2 H, d, JH-P = 20.8 Hz, CH ), 3.98 (4 H, dq, J = 7.1, 7.4 Hz, 2
2
×
CH O), 6.62 (1 H, dd, J = 3.8 Hz, Hthiophene), 6.78 (1 H, d, J = 3.8
2
HRMS: m/z calcd for C H FeN O S , 504.0629; found, 504.0627.
2
5
24
2
2 2
Hz, Hthiophene).
6
6
UV-VIS: λmax (CHCl ) = 488 (5.2 × 10 ), 616 (5.4 × 10 ).
3
1
3
P NMR (CDCl , 101 MHz): δ = 23.9
3
2
-Cyano-3-[(5′-ferrocenylvinyl)-thiophen-2′-yl]-but-2-enedi-
trans-Ferrocenyl-2-(5-bromothiophen-2-yl)ethylene (13)
nitrile (16)
To NaH (60% in oil, 12 mmol, 480 mg) washed twice with hexane
was added THF (10 mL) and 15-crown-5 (0.3 mmol, 66 mg, 10%).
A mixture of ferrocene carboxaldehyde 11 (3 mmol, 640 mg) and
phosphonate 12 (3 mmol, 1g) in THF (10 mL) was added slowly
and the suspension was stirred at r.t. overnight. The reaction was
To a solution of bromothiophene 13 (0.54 mmol, 200 mg) in THF
(
10 mL) at –78 °C was added slowly a solution of BuLi (1.6 M in
hexane, 1.2 equiv, 0.6 mmol, 375 µL) and the mixture was stirred at
78 °C 15 min. TCNE (0.7 mmol, 90 mg) was added at –78 °C and
–
the reaction was warmed to r.t. and stirred for 1 h. After hydrolysis,
the mixture was extracted with CH Cl (20 mL) , dried over MgSO ,
and concentrated. The residue was purified by flash chromatogra-
phy on silica gel and recrystallized from MeOH to give a green
powder (140 mg, 0.354 mmol, 66%); mp 178 °C.
quenched by adding H O (10 mL) at 0 °C, and the product was ex-
2
2
2
4
tracted with Et O (30 mL). The organic phase was dried (MgSO ),
2
4
the solvent evaporated, and the residue was purified by column
chromatography on silica gel (Et O–cyclohexane, 1:1). The product
2
was isolated as an orange powder (1.2 g, 3.22 mmol, 100%); mp
–
1
IR (KBr, CCl ): 2200 cm (CN).
1
29 °C.
4
1
1
H NMR (CDCl , 250 MHz): δ = 4.19 (s, 5 H, Cp), 4.55 (s, 4 H,
H NMR (250 MHz, CDCl ): δ = 4.12 (s, 5 H, Cp), 4.27 (AA′XX′
3
3
Cpsubst.), 6.80 (d, 1 H, J = 15.7 Hz, alkene), 7.10 (d, 1 H, J = 4.3 Hz,
thiophene), 7.21 (d, 1 H, J = 15.7 Hz, alkene), 7.90 (d, 1 H, J = 4.3
Hz, thiophene).
system, 2 H, J = 1.8 Hz, Cpsubst.), 4.39 (AA′XX′ system, 2 H, J = 1.8
Hz, Cpsubst.), 6.61 (d, 1 H, J = 15.9 Hz, alkene), 6.65 (d, 1 H, J = 3.8
Hz, thiophene), 6.68 (d, 1 H, J = 15.9 Hz, alkene), 6.88 (d, 1 H,
J = 3.8 Hz, thiophene).
Synthesis 2003, No. 3, 455–467 ISSN 0039-7881 © Thieme Stuttgart · New York

FEATURE ARTICLE
Design of Chiral Octupoles for Second Harmonic Generation
465
1
3
1
C NMR (CDCl , 63 MHz); δ = 68.45, 70.05, 71.9, 80.4, 112.8,
H NMR (CDCl , 250 MHz): δ = 4.17 (s, 15 H, Cp), 4.42 (t, 3 H,
3
3
1
12.95, 113.2, 126.4, 131.0, 131.5, 139.7, 141.85, 159.1.
J = 2.4 Hz, Cpsubst.), 4.61 (m, 3 H, Cpsubst.), 4.66 (m, 3 H, Cpsubst.),
6
.67 (d, 3 H, J = 3.8 Hz, thiophene), 6.78 (d, 3 H, J = 15.8 Hz,
HRMS: m/z calcd for C H N FeS, 395.0180; found, 395.0181.
2
1
13
3
alkene), 6.85 (d, 3 H, J = 3.8 Hz, thiophene), 6.93 (d, 3 H, J = 15.8
Hz, alkene), 7.65 (s, 3 H, aromatics).
6
6
UV-VIS: λmax (CHCl ) = 504 (9.2 × 10 ), 724 (9.5 × 10 ).
3
1
3
C NMR (CDCl , 63 MHz): δ = 65.7, 68.9, 71.2, 71.65, 82.2,
3
(
trans)-Ferrocenyl-(5-phenylethynylthiophen-2-yl)ethylene (17)
8
8.22, 110.15, 120.2, 124.9, 126.45, 128.85, 130.3, 137.7, 144.9.
Bromothiophene 13 (1.2 mmol, 450 mg), PdCl (PPh ) (0.06 mmol,
4
2
3 2
2 mg, 5%), PPh (0.03 mmol, 7.9 mg, 2.5%) and phenylacetylene
FABMS: m/z (%) = 1189.8 (100) [M+].
3
(1.8 mmol, 200 µL) were placed in a dry Schlenk tube under argon.
Et N (250 µL) in THF (10 mL) was added and the solution was
stirred at r.t. for 20 min. CuI (0.03 mmol, 6 mg, 2.5%) was then add-
ed and the solution stirred overnight. THF was removed in vacuo
1,3,5-Tri-{5′-[(trans)-(S)-ferrocen- -yl-vinyl]thiophen-2′-ylcar-
boxaldehydebenzene (20)
3
A solution of trisbromothiophene 19 (0.252 mmol, 300 mg) in an-
hyd THF (20 mL) was treated with BuLi (1.6 m in hexane, 0.832
mmol, 520 µL) at –78 °C. The reaction was warmed to r.t. and
stirred for 10 min. To this solution was added DMF (3.78 mmol,
220 µL) at –78 °C. The solution was warmed to r.t. and stirred for 2
h. A solution of HCl (1 M, 5 mL) was added and the product was
extracted with CH Cl (40 mL), dried over MgSO , concentrated
and the residue was dissolved in Et O and filtered on celite. The
2
product was purified by flash chromatography on silica gel (Et O–
2
cyclohexane, 1:2) and recrystallized from MeOH to give an orange
powder (400 mg, 1.015 mmol, 85%); mp 140 °C.
–
1
IR (KBr, CCl ): 2201 cm (C≡C).
4
2
2
4
1
H NMR (CDCl , 200 MHz): δ = 4.13 (s, 5 H, Cp), 4.29 (AA′XX′
3
and purified by flash chromatography (cyclohexane–EtOAc, 1:1).
system, 2 H, J = 1.8 Hz, Cpsubst.), 4.42 (AA′XX′ system, 2 H, J = 1.8
Hz, Cpsubst.), 6.71 (AB system, 2 H, J = 3.7 Hz, alkene), 6.81 (d, 1
H, J = 3.9 Hz, thiophene), 7.11 (d, 1 H, J = 3.9 Hz, thiophene), 7.32
The product was isolated as a red powder (262 mg, 0.252 mmol,
23
96%); mp 142 °C; [α]D
+975 (c 0.2, CHCl3).
–
1
IR (KBr, CHCl ): 1659 cm (CO).
3
(m, 3 H, phenyl), 7.5 (m, 2 H, phenyl).
1H NMR (CDCl
J = 2.5 Hz, Cpsubst.), 4.67 (m, 3 H, Cpsubst.), 4.73 (m, 3 H, Cpsubst.),
.89 (d, 3 H, J = 15.8 Hz, alkene), 7.02 (d, 3 H, J = 3.9 Hz,
, 200 MHz): δ = 4.19 (s, 15 H, Cp), 4.51 (t, 3 H,
1
3
3
C NMR (CDCl , 63 MHz): δ = 66.9, 69.3, 69.35, 82.4, 83.35,
3
9
3.65, 118.95, 120.4, 123.0, 124.35, 128.35, 131.3, 132.6, 140.25.
6
HRMS: m/z calcd for C H FeS, 394.0479; found, 394.0478.
2
4
18
thiophene), 7.29 (d, 3 H, J = 15.8 Hz, alkene), 7.55 (d, 3 H, J = 3.9
Hz, thiophene), 7.63 (s, 3 H, aromatics), 9.76 (s, 3 H, CHO).
2
,5-Dicyano-3-(5′-trans-ferrocenylvinyl-thiophen-2′-yl)-4-phe-
1
3
C NMR (CDCl , 63 MHz): δ = 65.85, 69.25, 70.8, 72.3, 79.8,
3
nyl-hexa-2,4-dienedinitrile (18)
In a dry Schlenk tube under argon were placed the alkyne 17 (0.51
mmol, 200 mg) and TCNE (0.51 mmol, 65 mg). CHCl (10 mL) was
8
1
9.05, 119.1, 125.1, 129.55, 131.65, 137.5, 137.6, 140.55, 153.1,
82.4.
3
added and the mixture was stirred for 2 h at 60 °C. CHCl was re-
HRMS Electrospray: m/z calcd for C H Fe O S Na, 1061.0246;
57 42 3 3 3
3
moved in vacuo and the product was purified by flash chromatogra-
found, 1061.0247.
phy on silica gel (cyclohexane–Et O, 3:1) and recrystallized from
2
MeOH to give a green powder (140 mg, 0.268 mmol, 53%), mp
1,3,5-Tri-{5′-{5′′-[(trans)-(S)-ferrocen- -yl-vinyl] thiophen-2′′-
ylmethylene}1′,3′-diethyl-2′-thioxo-dihydro-pyrimidine-4′,6′-
dione}benzene (22)
In a dry Schlenk tube were placed tris-thiophenealdehyde 20 (0.1
mmol, 100 mg), diethylthiobarbituric acid (1.5 mmol, 300 mg) and
1
92 °C.
–
1
IR (KBr, CCl ): 2222 cm (CN).
4
1
H NMR (CDCl , 200 MHz): δ = 4.19 (s, 5 H, Cp), 4.50 (m, 2 H,
3
Cpsubst.), 4.52 (m, 2 H, Cpsubst.), 6.79 (d, 1 H, J = 16 Hz, alkene), 7.08
KF on alumina (500 mg/mmol, 50 mg). CH CN (10 mL) was added
3
(
d, 1 H, J = 4.3 Hz, thiophene), 7.16 (d, 1 H, J = 16 Hz, alkene),
and the mixture was heated at 80 °C for 90 min. The solution was
7
.51–7.77 (m, 6 H, thiophene and phenyl).
cooled to r.t. and CH CN was removed in vacuo. The product was
3
1
3
dissolved in CH Cl (5 mL), filtered over celite, concentrated and
C NMR (CDCl , 63 MHz): δ = 68.2, 69.9, 71.45, 80.45, 111.1,
2
2
3
washed with MeOH (5 × 5 mL) to remove diethylthiobarbituric ac-
1
1
11.7, 113.45, 116.7, 126.6, 129.40, 129.95, 130.95, 131.15, 134.7,
38.5, 139.45, 150.8, 158.25, 167.7.
id. The product was isolated as a black powder (120 mg, 0.076
2
3
mmol, 79%); mp 225 °C; [α]D +2900 (c 0.01, CHCl3).
HRMS: m/z calcd for C H BrFeS, 522.0602; found, 522.0602.
3
0
13
–
1
IR (KBr, CHCl ): 1654 cm (CO).
6
6
3
UV-VIS: λmax (CHCl ) = 478 (8.3 × 10 ), 663 (8.2 × 10 ).
3
1
H NMR (CDCl , 250 MHz): δ = 1.26 (m, 18 H, CH ), 4.19 (s, 15
3
3
H, Cp), 4.53 (m, 15 H, Cpsubst.), 4.74 (m, 3 H, Cpsubst.), 4.77 (m, 3 H,
Cpsubst.), 6.97 (d, 3 H, J = 15.8 Hz, alkene), 7.21 (d, 3 H, J = 4.2 Hz,
thiophene), 7.55 (d, 3 H, J = 15.8 Hz, alkene), 7.64 (s, 3 H, aromat-
ics), 7.67 (d, 3 H, J = 4.2 Hz, thiophene), 8.53 (s, 3 H, CH).
13
1
,3,5-Tri-{[(trans)-(S)-ferrocen- -yl]-(5′-bromothiophen-2′-
yl)ethylene}benzene (19)
To NaH (60% in oil, 24 mmol, 960 mg, washed twice with hexane)
was added THF (30 mL) and 15-crown-5 (0.6 mmol, 132 mg, 10%).
The tris-aldehyde 1 (1.05 mmol, 750 mg) was added followed by a
solution of phosphonate 12 (6 mmol, 1.9 g) in THF (10 mL, slow
addition) and the solution was stirred at r.t. for 4 h. The mixture was
quenched by adding H O (20 mL) at 0 °C and extracted with
CH Cl (60 mL), dried over MgSO and concentrated. The product
was dissolved in CH Cl (100 mL), a few crystals of iodine were
C NMR (CDCl , 63 MHz) : δ = 12.35, 12.55, 42.95, 43.9, 66.05,
3
6
1
9.85, 71.05, 73.25, 79.75, 89.75, 109.15, 119.35, 125.9, 129.85,
34.15, 135.7, 137.8, 147.55, 149.1, 156.0, 160.5, 161.1, 178.6.
2
+
FABMS: m/z (%) = 1584.2 (100) [M – H].
2
2
4
3
3
UV-VIS: λmax (CHCl ) = 488 (65 × 10 ), 608 (40 × 10 ).
2
2
3
added and the mixture was stirred overnight at 50 °C under irradia-
tion (200 Watts). After washing the mixture with sodium thiosul-
1,3,5-Tri-{2′-cyano-3′-{5′′-[(S)-(trans)-ferrocen- -yl-vinyl]-
thiophen-2′′-yl}but-2-enedinitrile}benzene (23)
fate, the organic phases were collected, dried over MgSO and
4
concentrated. The product was purified by flash chromatography on
silica gel (cyclohexane–EtOAc, 8:2) to give a red-orange powder
(
A solution of tris-bromothiophene 19 (0.084 mmol, 100 mg) in an-
hyd THF (10 mL) was treated with BuLi (1.6 M in hexane, 0.277
mmol, 175 µL) at –78 °C. The reaction was warmed to r.t. and
stirred for 10 min. To this solution was added TCNE (0.84 mmol,
945 mg, 0.793 mmol, 76%); mp 125 °C; [α]D23 +520 (c 0.2,
CHCl3).
Synthesis 2003, No. 3, 455–467 ISSN 0039-7881 © Thieme Stuttgart · New York

4
66
V. Mamane et al.
FEATURE ARTICLE
+
1
2
07.5 mg) at –78 °C. The solution was warmed to r.t. and stirred for
h. The product was extracted with CH Cl (30 mL), dried over
FAB MS: m/z (%) = 1638.2 (100) [M – H].
2
2
3
3
UV-VIS: λmax (CHCl ) = 478 (53 × 10 ), 658 (39 × 10 ).
3
MgSO , concentrated and purified by flash chromatography (cyclo-
4
hexane–EtOAc, 4:1). The product was isolated as a green powder
NLO measurements
Harmonic Light Scattering Experiment
The approach followed here relies on Harmonic Light Scattering
2
3
(87 mg, 0.069 mmol, 82%); mp 150 °C; [α]D –2800 (c 0.01,
CHCl3).
–
1
10
IR (KBr, CHCl ): 2222 cm (CN).
(HLS) as initially proposed and developed by Terhune and Maker.
3
3
+
1
A transverse single mode Nd :YAG laser is used as the fundamen-
tal source, consisting of 500 MW peak power, 30 ns duration IR
pulses at 1.06 µm (repetition rate 10 Hz). This 1.06 beam pumps a
hydrogen-filled Raman cell (hydrogen pressure 50 bars) so as to
emit mid-infrared photons at 1.91 µm by Stimulated Raman Scat-
tering. The incident intensity of the 1.91 µm beam can be continu-
ously monitored by a half-wave plate rotated between two crossed
Glan polarizers. A small part of the incident beam is removed at a
low reflection angle by a glass plate and sent onto a highly nonlinear
H NMR (CDCl , 200 MHz): δ = 4.27 (s, 15 H, Cp), 4.70 (m, 3 H,
3
Cpsubst.), 4.82 (m, 6 H, Cpsubst.), 6.96 (d, 3 H, J = 15.7 Hz, alkene),
7
.16 (d, 3 H, J = 4.4 Hz, thiophene), 7.50 (d, 3 H, J = 15.7 Hz,
alkene), 7.52 (s, 3 H, aromatics), 7.89 (d, 3 H, J = 4.4 Hz,
thiophene).
1
3
C NMR (CDCl , 63 MHz) : δ = 66.05, 71.35, 71.4, 74.4, 78.75,
3
9
1
0.45, 112.7, 112.9, 113.05, 117.6, 127.0, 129.85, 131.15, 131.6,
37.4, 137.7, 141.6, 158.3.
3
9
FAB MS: m/z (%) = 1257.3 (100) [M+].
3
NPP (N-4-nitrophenyl-prolinol) powder used as a reference fre-
quency doubler. The emitted second harmonic signal is detected by
a photomultplier. The main fundamental beam is focused into the
sample using an 8 cm focal length converging lens. The sample con-
sists of an adequately designed parallelepipedic spectrophotometric
cell presenting four polished windows so as to allow for simulta-
neous longitudinal illumination and transverse collection of the
scattered emission. Solutions of increasing concentrations (ranging
3
UV-VIS: λmax (CHCl ) = 508 (29 × 10 ), 712 (27 × 10 ).
3
1
,3,5-Tri-{[(trans)-(S)-ferrocen- -yl-5′-phenylethynylthio-
phen-2′-yl]ethylene}benzene (21)
In a dry Schlenk tube were placed under argon tris-bromothiophene
1
9 (0.084 mmol, 100 mg), PdCl (MeCN) (0.05 mmol, 13 mg, 20%/
2 2
Br), PPh (0.1 mmol, 26.4 mg, 40%/Br) and CuI (0.05 mmol, 4.9
–2
–2
–1
3
from 10 to 10 ML ) of the molecules to be measured in CHCl
3
mg, 20%/Br). i-Pr NH (14 mL) and phenylacetylene (0.756 mmol,
2
are preliminary cleaned through 0.5 µm Millipore filters in order to
remove most microscopic particles which could otherwise induce
breakdowns in the presence of the focused laser beam. Collection of
the HLS photons at 955 nm is performed in the transverse off-axis
4
1.5 µL) were added and the mixture was stirred at r.t. for 30 min.,
the solution turning from light red to brown red. Temperature main-
tained at 70 °C and stirring was continued for 3 h. The solution was
cooled to r.t. and the product was extracted with CH Cl (30 mL).
2
2
9
0° direction, using a large (diameter 50 mm) and short focal dis-
After drying over MgSO , the product was concentrated and filtered
4
tance (f = 50 mm) spherical lens in order to focus the light onto the
photocathode of a photomultiplier tube. The numerical aperture of
the optical collection system is low so as to avoid the depolarizing
contribution of the off-axis beams. The detected reference and scat-
tered harmonic signals, after spectral selection through an interfer-
ence filter with 5 nm spectral resolution, are then sampled and
averaged using a Stanford Research System Boxcar and processed
by a computer. Variation of the scattered second harmonic intensity
from the solution is recorded on the computer as a function of the
reference second harmonic signal provided by the NPP powder,
which scales like the square of the incoming fundamental intensity.
on silica gel (Et O). Recrystallization from MeOH gave the product
2
2
3
as a red powder (83 mg, 0.066 mmol, 79%); mp 145 °C; [α]D –10
c 0.2, CHCl3).
(
–
1
IR (KBr, CHCl ): 2200 cm (alkyne).
3
1
H NMR (CDCl , 250 MHz): δ = 4.20 (s, 15 H, Cp), 4.45 (m, 3 H,
3
Cpsubst.), 4.66 (m, 3 H, Cpsubst.), 4.69 (m, 3 H, Cpsubst.), 6.84 (d, 3 H,
J = 3.5 Hz, thiophene), 6.86 (d, 3 H, J = 15.6 Hz, alkene), 7.08 (d,
3
H, J = 3.5 Hz, thiophene), 7.09 (d, 3 H, J = 15.6 Hz, alkene), 7.31
m, 9 H, aromatics), 7.45 (m, 6 H, aromatics), 7.70 (s, 3 H, aromat-
ics).
(
2
2
Then <β > and β [defined as square root (β )] values are inferred
from the slopes of the resulting lines. Calibrations are made with re-
1
3
C NMR (CDCl , 63 MHz): δ = 65.86, 68.5, 70.7, 71.4, 81.1, 88.1,
3
1
1
20.05, 120.75, 123.05, 124.6, 127.4, 128.35, 128.35, 129.2, 131.3,
32.75, 137.7, 145.25.
spect to the pure CHCl solvent.
3
FABMS: m/z (%) = 1254.2 (100) [M+].
Acknowledgment
1
,3,5-Tri-{2′,5′-dicyano-3′-{5′′-[(trans)-(S)-ferrocen- -ylvinyl]-
thiophen-2′′-yl}-4′-phenyl-hexa-2′,4′-dienedinitrile}benzene
24)
In a dry Schlenk tube were placed under argon tris-alcyne 21 (0.056
This work was supported by CNRS and Université Paris-Sud. V.M.
Acknowledges MRES for a fellowship.
(
mmol, 70 mg) and TCNE (0.5 mmol, 64.5 mg). CHCl (10 mL) was References
3
added and the solution was heated at 60 °C for 90 min. The reaction
(
1) New address : Laboratoire de Chimie Organique et
was cooled to r.t. and the product was filtered on silica gel (EtOAc),
concentrated and washed with MeOH (5 × 5 mL) to remove TCNE.
The product was isolated as a green powder (56 mg, 0.034 mmol,
Médicinale, Département de Chimie, Place Louis Pasteur 1,
Université catholique de Louvain, 1348 Louvain la neuve,
Belgium. Fax : +32(10)474168.
2
3
6
1%); mp 200 °C; [α]D –900 (c 0.01, CHCl3).
(
2) Chem. Phys. 1999, 245; special issue devoted to molecular
nonlinear optics.
–
1
IR (KBr, CHCl ): 2222 cm (CN).
3
1
H NMR (CDCl , 250 MHz): δ = 4.23 (s, 15 H, Cp), 4.64 (t, 3 H,
(3) (a) Chemla, D. S.; Zyss, J. Nonlinear Optical Properties of
Organic Molecules and Crystals, Vol.1; Academic Press:
New York, 1987. (b) Molecular Nonlinear Optics:
Materials Physics and Devices; Zyss, J., Ed.; Academic
Press: Boston, 1994. (c) Nonlinear Optics of Organic
Molecules and Polymers; Nalwa, H. S.; Miyata, S., Eds.;
CRC Press: Boca Raton, 1994.
3
J = 2.5 Hz, Cpsubst.), 4.78 (m, 6 H, Cpsubst.), 6.92 (d, 3 H, J = 5.7 Hz,
alkene), 7.09 (d, 3 H, J = 4.2 Hz, thiophene), 7.41 (d, 3 H, J = 15.7
Hz, alkene), 7.45–7.65 (m, 21 H, aromatics and thiophene).
1
3
C NMR (CDCl , 63 MHz): δ = 66.15, 70.65, 71.2, 73.95, 78.95,
3
8
1
1
9.65, 111.15, 111.65, 112.4, 117.95, 127.25, 129.1, 129.4, 129.95,
31.0, 131.25, 134.7, 136.3, 138.05, 139.25, 155.85, 157.35,
66.75.
Synthesis 2003, No. 3, 455–467 ISSN 0039-7881 © Thieme Stuttgart · New York

FEATURE ARTICLE
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Synthesis 2003, No. 3, 455–467 ISSN 0039-7881 © Thieme Stuttgart · New York