Chiral, flexible binaphthol-substituted tetrathiafulvalenes

Article abstract of DOI:10.1016/j.tet.2011.03.103

Novel chiral tetrathiafulvalene derivatives incorporating one or two binapthol moieties are described where two flexible (Ar-O)-CH ₂-CH₂-S-(TTF) links generate a large 14-membered ring on one or both sides of the TTF core. The symmet

Full text of DOI:10.1016/j.tet.2011.03.103

Tetrahedron 67 (2011) 3820e3829
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Chiral, flexible binaphthol-substituted tetrathiafulvalenes
*
ꢀ
Ali Saad, Oliver Jeannin, Marc Fourmigue
ꢀ
Sciences Chimiques de Rennes, Universite Rennes 1, UMR CNRS 6226, Campus de Beaulieu, 35042 Rennes, France
a r t i c l e i n f o
a b s t r a c t
Article history:
Novel chiral tetrathiafulvalene derivatives incorporating one or two binapthol moieties are described
where two flexible (AreO)eCH2eCH2eSe(TTF) links generate a large 14-membered ring on one or both
sides of the TTF core. The symmetric donor molecule with two chiral binaphthol moieties has been
prepared as enantiopure (RR) or (SS) isomer, as well as diastereomeric mixture containing the (RR), (SS),
and meso (RS)](SR) forms. Other unsymmetrically substituted derivatives bearing one single chiral bi-
naphthol substituent on one side were also prepared in their enantiopure (R) and (S) forms and as ra-
cemic mixture. X-ray crystal structure determinations of different donor molecules show that the TTF
tend to associate into face-to-face dyads with a strong folding of the dithiole rings along the S/S hinge
while the binaphthol moieties adopt a cisoid conformation with a dihedral angle between naphthyl rings
in the range 80e85ꢀ. The racemic EDT/TTF derivative allowed for the isolation of two crystalline charge-
transfer compounds with the electron acceptors TCNQ and TCNQF4. The donor and acceptor molecules
are organized into homo-dyads in the TCNQ neutral complex, insulating and diamagnetic. On the other
hand, a full charge transfer occurs in the TCNQF4 salt, with weakly interacting chiral TTF cation and
TCNQF4 anion radicals.
Received 3 March 2011
Accepted 29 March 2011
Available online 8 April 2011
Keywords:
Chirality
Atropoisomerism
Tetrathiafulvalene
Binaphthol
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
to the eventual presence of disorder in the racemic salts. As another
source of chirality, atropo-isomers as found in binaphthol de-
Following the early days of molecular conductors based on
partially oxidized donor molecules, such as perylene or tetrathia-
fulvalene,1 different recent strategies have been developed to
combine into multifunctional materials metallic conductivity with
other interesting properties,2 such as, for example, ferromagne-
tism,3 or chirality. Chiral conductors are particularly appealing for
the observation of a new phenomenon, referred to as the electrical
magneto-chiral anisotropy effect.4 As recently reviewed by Avarvari
and Wallis,5 two main strategies have emerged in the last years for
the elaboration of organic conductors derived from the prototypical
tetrathiafulvalene (TTF) donor molecule. The first one is based on
the synthesis of chiral TTF donor molecules, for further electro-
crystallization with a variety of anions; the second one takes ad-
vantage of the availability of various chiral anions, such as
antimony tartrate6 or camphorsulfonate7 to be used as electrolytes
in electrocrystallization experiments with achiral TTFs.
rivatives, are available with very high enantiomeric purity,13 and
their introduction on a tetrathiafulvalene core would favor chiral
solid state organizations through a combination of
pep in-
teractions and overlap interactions of open-shell molecules.
(a)
(b)
R
R
S
S
S
S
S
S
Ar
Me
S
S
S
S
S
S
N
O
(d)
(c)
S
S
S
S
S
S
N
R
R
S
S
O
O
S
S
Scheme 1. Examples of chiral TTF derivatives based on point chirality (aec) and axial
chirality (d).
Based on the TTF approach (Scheme 1), the very first chiral
tetrathiafulvalene described to date, was reported by Wallis and
Dunitz in a tetramethyl derivative of BEDT/TTF,8 and was followed
by a large number of other chiral TTF derivatives.9 More recently,
TTF oxazoline derivatives10 afforded a complete series of chiral
organic metals with (R)-, (S)- and racemic salts,11,12 highly sensitive
Actually, only a few TTF derivatives incorporating a binaphthyl
moiety have been described to date. Most of them are based on
a single binaphthol platform bearing a TTF moiety coupled to each
naphthalene ring, through either conjugated14 or non-conjugated
linkers,15,16 affording in all cases highly flexible molecules with
two TTF moieties per binaphthol unit. On the other hand, mono-
meric TTFs bearing one or two binaphthol moieties were only
* Corresponding author. Tel.: þ(33) 2 23 23 52 43; e-mail address: marc.four-
ꢀ
migue@univ-rennes1.fr (M. Fourmigue).
0040-4020/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2011.03.103

A. Saad et al. / Tetrahedron 67 (2011) 3820e3829
3821
reported very recently.17 These molecules, described in Scheme 1d,
Br
adopt a rigid structure with a constrained 10-membered ring in-
corporating the binaphthol moiety and limiting the possibility for
intermolecular interactions in the solid state. Looking for a less
constrained, extended link between the TTF and binaphthol moi-
eties, we envisioned the novel tetrathiafulvalene derivatives 1e5
(Scheme 2), where the binaphthol moiety is now anchored to the
TTF core through two flexible eCH2eCH2eSe links generating
a larger 14-membered ring. Accordingly, molecule 1 incorporating
two chiral binaphthol moieties has been prepared as enantiopure
(RR) and (SS) isomers, as well as diastereomeric mixture containing
the (RR), (SS), and meso (RS)](SR) forms. Other unsymmetrically
substituted derivatives 2e5 with one single chiral binaphthol
substituent were prepared in their enantiopure (R) and (S) forms
and as racemic mixture. The geometry adopted by the different
donor molecules in their crystalline state will be analyzed in details,
as well as their electrochemical properties. The favorable redox
potential and extended geometry of racemic EDT/TTF derivative
(R,S)-5 allowed for the isolation of two charge-transfer compounds
with the electron acceptors TCNQ and TCNQF4, whose structure and
properties will be analyzed in details.
(Et4N)2[Zn(dmit)2]
CH3CN/ reflux
PPh3/THF
OH
OH
O
O
Br(CH2)2OH
Br
(R)-8, (S)-8, (R,S)-8
S
S
S
S
O
O
Hg(OAc)2
CHCl3/AcOH
S
S
S
S
S
O
O
(R)-6, (S)-6, (R,S)-6
O
(R)-7, (S)-7, (R,S)-7
(RR)-1 (SS)-1
1
[(RR), (SS)
and (meso)]
S
S
S
S
S
S
O
O
O
O
S
S
S
S
S
S
S
S
O
O
O
O
S
S
1 (diastereomeric mixture)
(RR)-1, (SS)-1
Scheme 3. Synthesis of the chiral intermediates 6 and
substituted TTF 1.
7
and the symmetrically
as racemic mixture, were prepared by phosphite-mediated cross
coupling reaction of trithiocarbonate 6 with an excess of 4,5-bis-
(carboxymethyl)-1,3-dithiole-2-one (9) (Scheme 4), affording the
diesters 2 in 55% yield after recrystallization. TTF ortho-diesters
derivatives have been reported to react cleanly to the
2
3
4
R
R = CO2Me
R = CONH2
R = H
S
S
S
S
S
O
O
R
S
RR = S(CH2)2S 5
(R), (S) enantiomers
(R,S) racemic mixture
Scheme 2.
S
S
CO2Me
CO2Me
S
S
S
S
O
O
+
S
O
2. Results and discussion
2.1. Syntheses
9
(R)-6, (S)-6, (R,S)-6
The preparation of all TTFs described here (Scheme 3) is based on
phosphite-mediated cross coupling reactions involving the chiral
trithiocarbonate 6 or the dithiocarbonate 7. The key chiral in-
termediate 6 has been prepared in two steps from 1,10-bi-2-naphthol
(abbreviatedasbinaphtholinthefollowing). AsdescribedbyZhuetal.
with the (R) isomer of binaphthol,15 the Mitsunobu reaction between
binaphthol and 2-bromoethanol afforded the dibromo derivative 8 in
z60% yield. Alkylationof (Et4N)2[Zn(dmit)2] with (R)-8, (S)-8 or(R,S)-
8 was conducted in high dilution conditions to favor the formation of
cyclic trithiocarbonate (R)-6, (S)-6 and racemic (R,S)-6, affording the
three compounds in 80e85% yield. Oxymercuration with Hg(OAc)2
afforded the corresponding dithiocarbonates 7 in excellent yields.
Coupling of the latter in the presence of P(OMe)3 afforded the sym-
metrically substituted TTF 1 in 70e75% yield, either as a pure enan-
tiomer (RR)-1 and (SS)-1 when starting from (R)-6 and (S)-6,
respectively, while the coupling reaction of the racemic (R,S)-6
afforded the diastereoisomeric mixture which could not be separated
by silica gel chromatography.
CO2Me
CO2Me
S
S
S
S
S
P(OMe)3/ 130°C/4h
O
O
S
(R)-2, (S)-2, (R,S)-2
aq. NH3/THF
24h
CONH2
CONH2
S
S
S
S
S
O
O
S
(R)-3, (S)-3, (R,S)-3
LiBr/HMPA
145°C/20 mn
S
S
S
S
S
O
O
The unsymmetrically substituted TTFs ortho-diesters 2 in-
corporating one single binaphthol moiety are useful starting units
toward the corresponding primary amides 3, while their de-
carboxylation gives access to the simplest TTF derivatives of the
series, compounds 4. Compounds 2, either as pure enantiomers or
S
(R)-4, (S)-4, (R,S)-4
Scheme 4.

3822
A. Saad et al. / Tetrahedron 67 (2011) 3820e3829
corresponding ortho-diamides upon reaction with an excess of
ammonia or primary amines.18,19 Indeed, reaction of (R)-2, (S)-2 and
racemic (R,S)-2 with aqueous ammonia afforded the corresponding
primary diamides (R)-3, (S)-3 and racemic (R,S)-3 in excellent yields
(90%) as microcrystalline orange powders. Decarboxylation of the
diesters in the presence of LiBr at elevated temperatures,20 was also
successfully attempted and provided unsubstituted (R)-4, (S)-4, and
racemic (R,S)-4 compounds as orange crystals.
matches those reported for BEDT/TTF, demonstrating that our
substitution pattern incorporating the binaphthol moiety does not
modify significantly the redox ability of the TTF core. A similar
trend is observed for the other substituted TTFs 2e5 whose redox
potentials closely match those of the corresponding derivatives
with a simple ethylenedithio substituent.
2.2. Molecular and solid state structures of 1, 2, and 4
The preparation of the ethylenedithio (EDT) derivatives 5 is
based on similar cross coupling reactions, involving the trithiocar-
bonates 6 with an excess of dithiocarbonate 10. The cross coupling
product 5 is isolated after separation from the symmetrical prod-
ucts 1 and BEDT/TTF in 85% yield. Note that the alternative coupling
with the dithiocarbonate 7 and the trithiocarbonate analog of 10
afforded the desired product in significantly lower yields (45e60%)
(Scheme 5).
Good quality crystals could be obtained for the enantiopure
bis(binaphthol) compounds (RR)-1 and (SS)-1 upon recrystallization
from CH2Cl2/pentane. They both crystallize in the monoclinic sys-
tem, space group C2, with the molecule and the pentane located on
the twofold axis (Fig. 1). The TTF core exhibits strong distortions
from planarity with a folding of the central dithiole ring along the
S/S hinge, which amounts to 23.6 (1)ꢀ. The twist angle between the
two naphthyl moieties is found at 83.95 (3), that is, a cisoid confor-
mation, close however to the perpendicular orientation (90ꢀ).
S
S
S
S
S
S
S
S
O
O
+
S
O
10
(R)-6, (S)-6, (R,S)-6
S
S
S
S
S
S
S
S
P(OMe)3/ 130°C/4h
O
O
Fig. 1. View of (RR)-1.
(R)-5, (S)-5, (R,S)-5
This behavior contrasts with that observed on other binaphthol
derivatives where the two oxygen atoms are included in a cycle. 10-
membered derivatives, such as the TTF derivatives described ear-
lier17 (Scheme 1d) or the butylene derivative (Scheme 6a) exhibit
a systematic cisoid conformation with a dihedral angle between the
two naphthyl ring around 65e75ꢀ. The only structurally charac-
terized derivative with a 14-membered ring (Scheme 6b) adopts
a transoid conformation with a dihedral angle of 112.13ꢀ,23 dem-
onstrating the flexibility of these molecules even when constrained
in cycles.
Scheme 5.
Cyclic voltammetry experiments were performed on all newly
prepared TTF derivatives, in order to determine the donor capa-
bility, by comparison with known compounds. All TTF exhibit two
characteristic reversible oxidation waves (Table 1 and Figs. S1e5).
No differences are observed between the isomers of the same
compounds. As seen from Table 1, the redox potentials for 1 closely
Table 1
Cyclic voltammetry data for TTFs 1e5 and reference compounds (in V vs SCE)
(b)
(a)
CO2Me
S
S
S
S
S
S
S
S
S
S
S
S
Ph
P
O
O
O
S
S
CO2Me
S
S
O
BEDT-TTF
EDT-TTF(CO2Me)2
P
Ph
CONH2
CONH2
S
S
S
S
S
S
Scheme 6.
S
S
S
S
EDT-TTF
EDT-TTF(CONH2)2
Crystals of the racemic diester (R,S)-2 were obtained by
recrystallisation from CH2Cl2/petrol ether. (R,S)-2 crystallizes in the
triclinic system, space group Pꢁ1, with one molecule in the asym-
metric unit (Fig. 2a). The (R) and (S) isomers are associated into
inversion-centered dyads, with again a strong folding of the
dithiole rings along the S/S hinge, 19.01 (8)ꢀ along S1/S2, 20.01
(8)ꢀ along S3/S4, while the shortest intermolecular S/S distances
Compound
Solvent
E11=2
E12=2
Ref.
1
5
CH2Cl2
CH2Cl2
Cl(CH2)2Cl
0.56
0.52
0.56
0.95
0.92
0.96
This work
This work
21
BEDT/TTF
2
CH2Cl2
CH3CN
0.68
1.09
This work
22
ꢁ
amount to 3.64 A, at van der Waals contact. As observed in (RR)-
EDT/TTF(CO2Me)2
0.64a
0.95a
and (SS)-1, an almost perpendicular orientation between the two
naphthyl rings was found, with a dihedral angle of 86.20 (3)ꢀ.
The simpler TTF derivative 4 was also obtained in a crystalline
form in its racemic mixture (R,S)-4. It crystallizes in the triclinic
system, space group Pꢁ1, with one molecule in general position.
The outer unsubstituted dithiole ring of the TTF core is disordered
on two positions. As in (R,S)-2, the dithiole ring are folded, 20.66
3
CH2Cl2
THF
0.68
0.73
0.88
0.96
This work
19
EDT/TTF(CONH2)2
4
CH2Cl2
CH3CN
0.45
0.44
0.92
0.75
This work
20
EDT/TTF
a
Versus Ag/AgCl.

A. Saad et al. / Tetrahedron 67 (2011) 3820e3829
3823
Fig. 3. Organization within dyads in neutral (R)-5.
acetonitrile
and
formulated,
respectively
as
[(R,S)-5]
[TCNQ]$(CH3CN) and [(R,S)-5][TCNQF4]$(CH3CN)2.
The TCNQ compound crystallizes in the triclinic system, space
group Pꢁ1, with donor and acceptor molecules in general position
in the unit cell. As shown in Fig. 4, both donor (D) and acceptor (A)
are organized into inversion-centered dyads, alternating along the
b stacking axis into DDAADDAA mixed chains. Geometrical features
collected in Table 2 show a strong planarization of the TTF core (q1
and q2 close to 0ꢀ) while the Ci]Ci (a) and CieS (b) intramolecular
bond distances are slightly modified, when compared with the
neutral (R)- or (S)-5, indicating some degree of charge transfer.
Based on the large number of reported TCNQ salts, different cor-
relations24 between the charge of the molecule and the bond
lengths within the TCNQ molecule have been reported. Applying
those correlations to the TCNQ bond lengths in [(R,S)-5]
[TCNQ]$(CH3CN), averaged in D2h symmetry, gives calculated
charges of zꢁ0.25, thus indicating the possibility for a partial
charge transfer in this TCNQ compound. The TTF and TCNQ homo-
dyads interact only sideways as shown in Fig. 5. These unusual
overlaps are associated with long inter-atomic distances; all S/S
Fig. 2. Organization within centrosymmetric dyads in (a) racemic diester (R,S)-2, (b)
racemic TTF (R,S)-4.
(9), 22 (1), and 16 (1)ꢀ along the S3/S6, S1/S2, and S1A/S2A
hinges, respectively while the binaphthyl rings adopt a cisoid con-
formation with a dihedral angle of 79.91 (3). Intermolecular S/S
ꢁ
distances within the inversion-centered dyads exceed 4 A.
2.3. The EDT/TTF derivatives 5 and their salts
Chemical oxidation of the different donor molecules 1e5 with
TCNQ or TCNQF4 afforded crystals only with the racemic EDT/TTF
derivative (R,S)-5. In the following, we will first describe the X-ray
crystal structures obtained for the neutral enantiopure (R)-5 and
(S)-5, which will provide us with reference data for the intra-
molecular bond distances within the TTF core in 5. In a second
part, we will discuss the structures of the TCNQ and TCNQF4 salts,
in order to determine the degree of charge transfer within the
two compounds, and its correlation with the electronic
properties.
ꢁ
contacts in the TTF dyads exceed 3.68 A, all C/C contacts in the
ꢁ
TCNQ dyads exceed 3.54 A. These geometrical features and the
mixed-stack character are not in favor of a sizeable charge transfer,
by contrast with other known BEDT/TTF salts with TCNQ itself.25
(R)-5 and (S)-5 are isostructural, they crystallize both in the
orthorhombic system, space group P212121, with two crystallo-
graphically independent molecules in the asymmetric unit, to-
gether with two CH2Cl2 molecules. Geometrical characteristics are
collected in Table 2. Note again the strong distortion from planarity
of the TTF core. In the solid state, the molecules are associated two-
by-two (Fig. 3) with the shortest S/S intermolecular distance
ꢁ
(3.74 A) close the sum of van der Waals radii.
Reactions of the enantiopure (R)-5 or (S)-5 molecules with TCNQ
or TCNQF4 afforded only very soluble material, which could not be
properly crystallized. On the other hand, slow cooling of warm
CH3CN solutions of racemic (R,S)-5 with equimolar amount of TCNQ
or TCNQF4 afforded in both cases 1:1 compounds incorporating
Fig. 4. Projection view along a of the unit cell of [(R,S)-5][TCNQ],(CH3CN).
Table 2
Structural characteristics of the EDT/TTF derivatives 5. The a distance refers to the
central Ci]Ci and b to the averaged CieS intramolecular distances. q1 and q2 are the
folding angles of the dithiole ring, on the EDT and binaphthol side, respectively. q3 is
the dihedral angle between naphthyl moieties
The magnetic susceptibility of this TCNQ compound was de-
termined in the 5e300 K temperature range and exhibits a tem-
perature-independent diamagnetic behavior with c0¼ꢁ7.6
10ꢁ4 cm3 molꢁ1 with a Curie-type contribution of magnetic de-
faults accounting for less than 1% spin ½, demonstrating un-
ambiguously the absence of charge transfer in this neutral complex.
Conductivity measurements performed on this salt confirmed this
ꢁ
ꢁ
Compound
a (A)
b (A)
q1 (ꢀ)
q2 (ꢀ)
q3 (ꢀ)
(R)-5 mol A
mol B
(S)-5 mol A
mol B
1.339 (5) 1.762 (3) 31.8 (2) 23.2 (2) 76.00 (6)
1.342 (5) 1.762 (3) 30.3 (2) 13.9 (2) 73.98 (6)
1.341 (4) 1.762 (3) 31.3 (1) 22.8 (2) 76.26 (4)
1.344 (4) 1.761 (3) 30.1 (1) 13.6 (1) 74.24 (4)
1.37 (1) 1.748 (9) 3.9 (6) 2.3 (6) 74.1 (1)
zero charge transfer with a conductivity less than 10ꢁ6 S cmꢁ1
.
[(R,S)-5](TCNQ),CH3CN
The TCNQF4 salt crystallizes in the triclinic system, space group
Pꢁ1, with donor and acceptor molecules in general position in the
[(R,S)-5],(TCNQF4),(CH3CN)2 1.401 (5) 1.727 (5) 0.4 (2) 6.6 (2) 74.43 (7)

3824
A. Saad et al. / Tetrahedron 67 (2011) 3820e3829
The temperature dependence of the magnetic susceptibility of
ꢂ
ꢁ
the TCNQF4 salt (Fig. 7) confirms its biradical nature with a
c$T
value close to 0.6. The T decrease at lower temperatures indicates
c
the presence of antiferromagnetic interactions between the radicals.
We have identified two different interactions within each chain,
either built on the EDT/TTF 5 or TCNQF4 molecules, highlighted in
Fig. 6b with thick and thin lines, respectively (see also Fig. SII). The
evolution of
c
$T versus T can be fitted as the sum of two contribu-
tions originating from each of the EDT/TTFþꢂ and TCNQF4
ꢁ
radical
ꢂ
species, both associated into inversion-centered dyads with a sin-
glet-triplet behavior, that is, according to the following equation:
Ng2b2
kT
c
¼
c0 þ x$cCurie þ ð1 ꢁ xÞ
ꢀ
ꢁ
1
1
ꢃ
þ
3 þ expð ꢁ J1=kTÞ 3 þ expð ꢁ J2=kTÞ
Fig. 5. View of the chains of dyads running along the
[TCNQ],(CH3CN).
a axis in [(R,S)-5]
where x is a fraction of paramagnetic defaults and J1 and J2 the two
antiferromagnetic interactions associated with the radical dyads,
which are found at ꢁ40 and ꢁ180 cmꢁ1, respectively. The shorter
S/S intermolecular contacts observed within the TTF chains let us
infer that the strongest interactions are due here to the TTF chains.
unit cell. Comparison of the bond distances within the TTF core
with neutral (R)- or (S)-5 (Table 2) shows a marked lengthening of
the central Ci]Ci bond (a) with concomitant shortening of the CieS
bonds (b), indicating clearly that the EDT/TTF 5 is here oxidized into
the radical cation. This is further confirmed by the bond distances
within the TCNQF4 moiety as well as by the CN stretching vibration
(2191, 2165 cmꢁ1).26,27 The compound is thus formulated as [(R,S)-
5]þꢂ[TCNQF4]ꢁꢂ(CH3CN)2. As shown in Fig. 6, the donor molecule is
now fully planar and intercalated between TCNQF4 molecules to
form an alternated DADADA mixed-stack running along a. These
chains are connected to each other along the b direction within (ab)
layers (Fig. 6b) with the radical molecules interacting sideway
along b.
Fig. 7. Temperature dependence of the
c,T product for [(R,S)-5][TCNQF4].(CH3CN)2.
The red solid line is a fit to the sum of two singlet-triplet systems, together with a Curie
tail attributable to paramagnetic defaults.
3. Conclusions
In conclusion, we have described here a complete series of chiral
binaphthol-based tetrathiafulvalene donor molecules where longer
and flexible eSe(CH2)2e arms offer the possibility for direct in-
termolecular
pep interactions, as illustrated in the structures of
the neutral derivatives 2, 4, and 5, where molecules systematically
associate into dyads with the TTF moieties facing each other
through S/S van der Waals interactions. Furthermore, we have
also demonstrated that such chiral donor molecules can be effec-
tively oxidized into cation radical species, and are able to interact in
the solid state, as illustrated here within two compounds of the
racemic EDT/TTF derivative 5 with TCNQ and TCNQF4. Electro-
crystallization experiments aimed at isolating cation radical salts of
these promising donor molecules, particularly in its enantiopure
form, with various closed-shell counter ions are now in progress.
4. Experimental section
4.1. General
Fig. 6. (a) Projection view of the unit cell of [(R,S)-5][TCNQF4]$(CH3CN)2 along a. Hy-
drogen atoms were omitted for clarity. (b) Solid state organization of the radical
species. The thick and thin lines are associated with stronger and weaker overlap in-
teractions between TTF in red, between TCNQF4 LUMO in blue. The binaphthol moi-
eties have been omitted for clarity.
Enantiopure (R)-, (S)-, and racemic (R,S)-binaphthol were
obtained from Aldrich and used as received. The zinc salt
(Et4N)2[Zn(dmit)2]28 and the dithiocarbonate 1029 were prepared

A. Saad et al. / Tetrahedron 67 (2011) 3820e3829
3825
following published procedures. NMR spectra (1H, 13C) were
recorded on a Bruker Avance 300 spectrometer, chemical shifts are
reported in parts per million referenced to TMS for 1H and 13C NMR.
Cyclic voltammetry was carried out on a 1.5ꢃ10ꢁ3 M solution of TTF
derivative in CH2Cl2 (anhydrous grade) containing 0.2 M n-Bu4NPF6
as supporting electrolyte. Voltammograms were recorded at
0.1 V sꢁ1 on a platinum disk electrode (1 mm2). Potentials were
measured versus Saturated Calomel Electrode (SCE). Optical rota-
tion was determined on a PerkineElmer 341 polarimeter with c
given in g/100 mL. Circular dichroism spectra (Fig. S6e10) were
recorded on a JASCO J-815 spectropolarimeter with 5 10ꢁ5 M so-
lutions. Elemental analyses were performed at the CNRS Service de
Microanalyse, Gif sur Yvette, France.
CDCl3, ppm):
d
211.98, 153.66, 140.64, 134.25, 129.50, 129.35, 127.98,
126.47, 125.31, 123.73, 119.66, 114.90, 66.26, 37.84. Elem. Anal. Calcd
for C27H20O2S5 (536.01): C, 60.41; H, 3.76. Found: C, 59.99; H, 3.81.
4.3.2. Synthesis of (R)-6. As above for (R,S)-6 starting from enan-
tiopure (R)-8 (2.65 g, 5.3 mmol). (R)-6 is isolated as yellow crystals
20
(2.45 g, 86%). Mp 135e137 ꢀC. ½
a
ꢄ
þ964 (c 0.05, CH2Cl2). 1H NMR
Na
(300 MHz, CDCl3, ppm):
d
7.99 (d, J¼9.0 Hz, 2H), 7.89 (d, J¼8.0 Hz,
2H), 7.37 (d, J¼9.0 Hz, 2H), 7.34 (ddd, J¼8.1, 6.4, 1.4 Hz, 2H), 7.24
(ddd, J¼8.1, 6.4, 1.4 Hz, 2H), 7.15 (d, J¼8.4 Hz, 2H), 4.31 (dt, J¼10.1,
4.0 Hz, 2H), 4.18 (td, J¼9.9, 3.2 Hz, 2H), 3.03 (dt, J¼14.4, 3.5 Hz, 2H),
2.84 (ddd, J¼14.2, 9.8, 4.2 Hz, 2H). 13C NMR (75 MHz, CDCl3, ppm):
d
211.97, 153.65, 140.61, 134.25, 129.50, 129.35, 127.98, 126.47,
125.30, 123.73, 119.67, 114.90, 66.26, 37.83. Elem. Anal. Calcd for
C27H20O2S5 (536.01): C, 60.41; H, 3.76. Found: C, 60.18; H, 3.71.
4.2. Synthesis of 2,20-bis(2-bromoethoxy)-1,10-binaphthyl 8
4.2.1. Synthesis of racemic (R,S)-8. To a solution of binaphthol
(3.46 g, 12 mmol) and PPh3 (9.5 g, 36.22 mmol) in THF (75 mL) at
room temperature (rt) and under Ar is added dropwise during 2 h
a mixture of 2-bromoethanol (2.56 mL, 36.04 mmol) and DEAD
(azodicarboxylic acid diethyl ester, 40% solution in toluene, 16.5 mL,
36.3 mmol). After stirring overnight and solvent removal, the pale
yellow oil is purified by chromatography on silica gel (CH2Cl2/petrol
ether, 1:3). Recrystallisation from CH2Cl2/hexane at 5 ꢀC gives (R,S)-
8 as white needles (3.3 g, 57%). Mp 106 ꢀC. 1H NMR (300 MHz,
4.3.3. Synthesis of (S)-6. As above for (R,S)-6 starting from enan-
tiopure (S)-8 (4.5 g, 8.99 mmol). (S)-6 is isolated as yellow crystals
20
(4 g, 85%). Mp 130e132 ꢀC. ½
a
ꢄ
ꢁ970 (c 0.05, CH2Cl2). 1H NMR
Na
(300 MHz, CD2Cl2, ppm):
d
8.05 (d, J¼9.0 Hz, 1H), 7.95 (d, J¼8.1 Hz,
2H), 7.45 (d, J¼9.0 Hz, 2H), 7.39 (ddd, J¼8.1, 6.7, 1.2 Hz, 2H), 7.27
(ddd, J¼8.0, 6.7, 1.2 Hz, 2H), 7.16 (d, J¼8.4 Hz, 2H), 4.33 (dt, J¼10.0,
3.9 Hz, 2H), 4.24 (td, J¼10.1, 3.0 Hz, 2H), 3.06 (dt, J¼14.4, 3.2 Hz, 2H),
2.84 (ddd, J¼14.3,10.0, 4.2 Hz, 2H). 13C NMR (75 MHz, CD2Cl2, ppm):
d
212.84, 154.28, 141.69, 134.65, 129.89, 129.73, 128.49, 126.84,
CDCl3, ppm):
d
7.99 (d, J¼9.0 Hz, 2H), 7.91 (d, J¼8.1 Hz, 2H), 7.45 (d,
125.56, 124.10, 119.74, 115.26, 66.56, 38.44. Elem. Anal. Calcd for
C27H20O2S5 (536.01): C, 60.41; H, 3.76. Found C, 59.94; H, 3.68.
J¼9.0 Hz, 2H), 7.42e7.32 (m, 2H), 7.32e7.22 (m, 2H), 7.17 (d,
J¼8.4 Hz, 2H), 4.35e4.14 (m, 4H), 3.25 (t, J¼6.7 Hz, 4H). 13C NMR
(75 MHz, CDCl3, ppm):
d
153.57, 134.05, 129.83, 129.73, 128.01,
4.4. Synthesis of the dithiocarbonates 7
126.57, 125.44, 124.19, 121.08, 116.38, 69.94, 29.23.
4.4.1. Synthesis of (R,S)-7. To a solution of the racemic 1,3-dithiole-
2-thione (R,S)-6 (1 g, 1.86 mmol) in a mixture CHCl3/AcOH (50 mL,
3/2 v/v) is added Hg(OAc)2 (1.8 g, 2.5 equiv, 5.65 mmol) at rt. After
stirring for 4 h, the white insoluble is filtered on Celite and washed
with CH2Cl2. The organic filtrate is washed with H2O, satd NaHCO3,
H2O, dried over MgSO4, and concentrated. Chromatography on
silica gel (CH2Cl2/petrol ether, 2:1) and recrystallisation from
CH2Cl2/petrol ether afforded (R,S)-7 as white needles (0.97 g, 95%).
4.2.2. Synthesis of (R)-8. As described above for (R,S)-8, starting
from (R)-binaphthol, one obtains (R)-8 as white crystals (3.86 g,
64%). Mp 99 ꢀC (lit.15 97.5e98.9 ꢀC). 1H NMR (300 MHz, CDCl3,
ppm):
d
7.97 (d, J¼8.9 Hz, 2H), 7.89 (d, J¼8.1 Hz, 2H), 7.43 (d,
J¼9.0 Hz, 2H), 7.37 (ddd, J¼8.1, 6.7, 1.3 Hz, 2H), 7.25 (ddd, J¼8.1, 5.6,
1.3 Hz, 2H), 7.17e7.10 (m, 2H), 4.32e4.12 (m, 4H), 3.23 (t, J¼6.8 Hz,
4H). 13C NMR (75 MHz, CDCl3, ppm):
d 153.55, 134.03, 129.82,
129.71, 127.99, 126.55, 125.42, 124.17, 121.07, 116.37, 69.93, 29.18.
Mp 195 ꢀC. 1H NMR (300 MHz, CDCl3, ppm):
d
7.98 (d, J¼9.0 Hz, 2H),
7.89 (d, J¼8.1 Hz, 2H), 7.37 (d, J¼9.0 Hz, 2H), 7.37e7.32 (m, 2H),
7.27e7.21 (m, 2H), 7.16 (d, J¼8.4 Hz, 2H), 4.29 (dt, J¼9.9, 4.0 Hz, 2H),
4.18 (td, J¼9.9, 3.2 Hz, 2H), 3.00 (dt, J¼14.3, 3.4 Hz, 2H), 2.80 (ddd,
4.2.3. Synthesis of (S)-8. As described above for (R,S)-8, starting
from (S)-binaphthol (5 g, 17.4 mmol), PPh3 (12.2 g, 46.5 mmol) in
THF (100 mL) with 2-bromoethanol (3.7 mL, 52.1 mmol) and DEAD
(40% solution in toluene) (23.85 mL, 52.47 mmol), one obtains (S)-8
as white crystals (5.7 g, 65%). Mp 98 ꢀC. 1H NMR (300 MHz, CDCl3,
J¼14.2, 9.7, 4.2 Hz, 2H). 13C NMR (75 MHz, CDCl3, ppm):
d 189.49,
153.78,134.28,131.54,129.46, 129.33,127.96,126.44,125.32,123.69,
119.68, 114.98, 66.22, 37.53. Elem. Anal. Calcd for C27H20O3S4
(520.71): C, 62.28; H, 3.87. Found: C, 62.08; H, 3.92.
ppm):
d
8.01 (d, J¼8.9 Hz, 2H), 7.93 (d, J¼8.1 Hz, 2H), 7.47 (d,
J¼9.0 Hz, 2H), 7.41 (ddd, J¼8.1, 6.6, 1.4 Hz, 2H), 7.29 (ddd, J¼7.9, 6.6,
1.3 Hz, 2H), 7.24e7.18 (m, 2H), 4.36e4.17 (m, 4H), 3.27 (t, J¼6.7 Hz,
4.4.2. Synthesis of (R)-7. As above for (R,S)-7, starting from the
enantiopure 1,3-dithiole-2-thione (R)-6 (1.9 g, 3.7 mmol) and
4H). 13C NMR (75 MHz, CDCl3, ppm):
d 153.62, 134.10, 129.86,
129.78, 128.07, 126.62, 125.49, 124.23, 121.09, 116.40, 69.96, 29.33.
Hg(OAc)2 (2.85 g, 2.5 equiv, 8.94 mmol), one obtains (R)-7 as
20
a white powder (1.84 g, 100%). Mp 127e130 ꢀC. ½
a
ꢄ
þ564 (c 0.05,
Na
4.3. Synthesis of the trithiocarbonates 6
CH2Cl2). 1H NMR (300 MHz, CD2Cl2, ppm):
d
8.03 (d, J¼8.9 Hz, 2H),
7.94 (d, J¼8.1 Hz, 2H), 7.45 (d, J¼9.0 Hz, 2H), 7.37 (ddd, J¼8.1, 6.7,
1.3 Hz, 2H), 7.25 (ddd, J¼8.1, 6.7, 1.3 Hz, 2H), 7.16e7.09 (m, 2H), 4.36
(dt, J¼10.1, 4.0 Hz, 2H), 4.26 (td, J¼10.0, 3.1 Hz, 2H), 3.08 (dt, J¼14.4,
3.3 Hz, 2H), 2.85 (ddd, J¼14.3, 9.9, 4.2 Hz, 2H). 13C NMR (300 MHz,
4.3.1. Synthesis of racemic (R,S)-6. To a solution of (Et4N)2[Zn(d-
mit)2] (2.5 g, 3.6 mmol) in CH3CN (3 L) is added (R,S)-8 (3.35 g,
6.7 mmol) at rt. After stirring for five days under reflux, the cooled
solution is evaporated, the residue taken in H2O (500 mL) and
extracted with CH2Cl2 (3ꢃ350 mL). The organic phase is washed
with H2O (3ꢃ350 mL), dried over MgSO4, and the residue purified
by chromatography on silica gel (CH2Cl2/petrol ether, 1:1) to afford
the racemic (R,S)-6 as a yellow powder (2.9 g, 81%). Mp 215e217 ꢀC.
CD2Cl2, ppm):
d 189.84, 154.35, 134.63, 132.33, 129.81, 129.69,
128.41, 126.75, 125.51, 124.02, 119.74, 115.30, 66.52, 38.07. MS
(MALDI-TOF) m/z 519.4 (Mþ). Elem. Anal. Calcd for C27H20O3S4
(520.71): C, 62.28; H, 3.87. Found: C, 62.65; H, 4.46.
1H NMR (300 MHz, CDCl3, ppm):
d
7.89 (d, J¼8.9 Hz, 2H), 7.80 (d,
4.4.3. Synthesis of (S)-7. As above for (R)-7, starting from 1,3-
dithiole-2-thione (S)-6 (1 g, 1.86 mmol) and Hg(OAc)2 (1.8 g,
J¼8.0 Hz, 2H), 7.37 (d, J¼9.0 Hz, 2H), 7.34 (ddd, J¼8.1, 6.4, 1.4 Hz,
2H), 7.25 (ddd, J¼8.1, 6.4, 1.4 Hz, 2H), 7.19e7.11 (m, 2H), 4.22 (dt,
J¼10.1, 4.0 Hz, 2H), 4.08 (td, J¼9.9, 3.2 Hz, 2H), 2.93 (dt, J¼14.4,
3.4 Hz, 2H), 2.74 (ddd, J¼14.2, 9.8, 4.2 Hz, 2H). 13C NMR (75 MHz,
2.5 equiv, 4.65 mmol), one obtains (S)-7 as a white powder (0.97 g,
20
100%). Mp 125 ꢀC. ½
a
ꢄ
ꢁ560 (c 0.05, CH2Cl2). 1H NMR (300 MHz,
Na
CD2Cl2, ppm):
d
8.04 (d, J¼8.9 Hz, 2H), 7.95 (d, J¼8.1 Hz, 2H), 7.45 (d,

3826
A. Saad et al. / Tetrahedron 67 (2011) 3820e3829
J¼9.0 Hz, 2H), 7.38 (ddd, J¼8.1, 6.7, 1.3 Hz, 2H), 7.26 (ddd, J¼8.1, 6.7,
1.3 Hz, 2H), 7.18e7.12 (m, 2H), 4.34 (dt, J¼10.0, 4.0 Hz, 2H), 4.26 (td,
J¼10.0, 3.0 Hz, 2H), 3.06 (dt, J¼14.4, 3.3 Hz, 2H), 2.83 (ddd, J¼14.3,
(d, J¼8.5 Hz, 2H), 4.24 (dt, J¼10.1, 4.1 Hz, 2H), 4.04 (td, J¼9.7,
3.1 Hz, 2H), 3.85 (s, 6H), 3.01 (dt, J¼7.3, 3.2 Hz, 2H), 2.80e2.67 (m,
2H). 13C NMR (75 MHz, CDCl3, ppm):
d 159.94, 153.93, 134.24,
9.9, 4.3 Hz, 2H). 13C NMR (75 MHz, CD2Cl2, ppm):
d
189.90, 154.39,
132.00, 131.16, 129.42, 129.37, 127.92, 126.37, 125.28, 123.67,
119.77, 115.62, 112.53, 107.88, 66.91, 53.43, 37.08. MS (MALDI-
TOF) m/z 721.9 (Mþ). Elem. Anal. Calcd for C34H26O6S6 (722.96): C,
56.49; H, 3.62. Found: C, 55.99; H, 3.46.
134.65,132.48, 129.85,129.69,128.46,126.81,125.54,124.06,119.70,
115.30, 66.47, 38.10. Elem. Anal. Calcd for C27H20O3S4 (520.71): C,
62.28; H, 3.87. Found: C, 62.03; H, 3.94.
4.5. Synthesis of the symmetrically substituted TTFs (1)
4.6.2. Synthesis of (R)-2. As described above for (R,S)-2, starting
from the enantiopure 1,3-dithiole-2-thione (R)-6 (1 g, 1.86 mmol),
20
4.5.1. Synthesis of 1 (diastereoisomeric mixture). A solution of the
racemic 1,3-dithiole-2-one (R,S)-7 (0.5 g, 0.96 mmol) in P(OMe)3
(10 mL) is warmed to 130 ꢀC during 5 h under Ar. After cooling to
rt, the phosphite is evaporated and the residue purified by chro-
matography on silica gel (CH2Cl2/petrol ether 2:1). Recrystallisa-
tion from CH2Cl2/pentane afforded the diastereoisomeric mixture
1 [(RR) (SS) and meso form (RS)](SR)] as a yellow powder
one obtains (R)-2 as a red powder (740 mg, 55%). Mp 147 ꢀC. ½
ꢄ
a
Na
þ678 (c 0.05, CH2Cl2). 1H (300 MHz, CDCl3, ppm):
d 7.95 (d,
J¼8.9 Hz, 2H), 7.87 (d, J¼8.0 Hz, 2H), 7.37 (d, J¼9.0 Hz, 2H), 7.32
(ddd, J¼8.0, 6.7, 1.3 Hz, 2H), 7.22 (ddd, J¼8.0, 6.7, 1.3 Hz, 2H), 7.13 (d,
J¼8.5 Hz, 2H), 4.23 (dt, J¼10.0, 4.1 Hz, 2H), 4.04 (td, J¼9.7, 3.1 Hz,
2H), 3.85 (s, 6H), 3.00 (dt, J¼7.2, 3.3 Hz, 2H), 2.80e2.67 (m, 2H). 13C
NMR (75 MHz, CDCl3, ppm): d 160.04,154.03, 134.34, 132.09, 131.25,
(340 mg, 70%). Mp 260 ꢀC. 1H NMR (300 MHz, CD2Cl2, ppm):
d
7.9
129.52, 129.47, 128.02, 126.47, 125.37, 123.76, 119.87, 115.71, 112.62,
107.99, 67.00, 53.52, 37.17. MS (MALDI-TOF) m/z 722 (Mþ). Elem.
Anal. Calcd for C34H26O6S6 (722.96): C, 56.49; H, 3.62. Found: C,
56.19; H, 3.42.
(d, J¼9.0 Hz, 4H), 7.80 (d, J¼8.0 Hz, 4H), 7.32 (d, J¼9.0 Hz, 4H), 7.24
(t, J¼7.3 Hz, 4H), 7.12 (t, J¼7.4 Hz, 4H), 6.98 (d, J¼8.4 Hz, 4H),
4.21e4.18 (m, 4H), 4.01e3.96 (m, 4H), 2.98e2.93 (m, 4H),
2.72e2.60 (m, 4H). 13C NMR (75 MHz, CD2Cl2, ppm):
d 154.45,
134.60, 131.70, 129.75, 129.69, 128.36, 126.70, 125.47, 124.01,
119.82, 115.73, 110.10, 67.15, 67.06, 37.48. MS (MALDI-TOF) m/z
1008.1 (Mþ). Elem. Anal. Calcd for C54H40O4S8 (1009.41): C, 64.25;
H, 3.99. Found: C, 64.02; H, 4.09.
4.6.3. Synthesis of (S)-2. As described above for (R,S)-2 starting from
the enantiopure 1,3-dithiole-2-thione (S)-6 (1 g, 1.86 mmol), one
20
obtains (S)-2 as a red powder (740 mg, 55%). Mp 150 ꢀC. ½
a
ꢄ
ꢁ678
Na
(c 0.05, CH2Cl2). 1H NMR (300 MHz, CD2Cl2, ppm):
d
8.01 (d, J¼8.9 Hz,
2H), 7.92 (d, J¼8.0 Hz, 2H), 7.44 (d, J¼9.0 Hz, 2H), 7.36 (ddd, J¼8.1, 6.7,
1.3 Hz, 2H), 7.24 (ddd, J¼8.1, 6.7, 1.3 Hz, 2H), 7.11 (d, J¼8.5 Hz, 2H),
4.29 (dt, J¼10.1, 3.9 Hz, 2H), 4.13 (td, J¼9.9, 3.0 Hz, 2H), 3.86 (s, 6H),
3.07 (dt, J¼6.9, 3.2 Hz, 2H), 2.84e2.70 (m, 2H). 13C NMR (75 MHz,
4.5.2. Synthesis of (RR)-1. As described above, starting from the
enantiopure 1,3-dithiole-2-one (R)-6 (0.5 g, 0.96 mmol) in P(OMe)3
(5 mL), one obtains (RR)-1 as orange crystals (360 mg, 75%). Mp
20
220e222 ꢀC. ½
a
d
ꢄ
þ1020 (c 0.05, CH2Cl2). 1H NMR (300 MHz,
CD2Cl2, ppm): d 160.31, 154.47, 134.59, 132.28, 131.95, 129.80, 129.72,
Na
CD2Cl2, ppm):
7.88 (d, J¼8.9 Hz, 4H), 7.79 (d, J¼8.0 Hz, 4H), 7.31 (d,
128.41, 126.73, 125.47, 124.03, 119.83, 115.85, 112.88, 108.04, 67.21,
53.85, 37.60. MS (MALDI-TOF) m/z 721.6 (Mþ). Elem. Anal. Calcd for
C34H26O6S6 (722.96): C, 56.49; H, 3.62. Found: C, 56.29; H, 3.59.
J¼9.0 Hz, 4H), 7.23 (ddd, J¼8.1, 6.8, 1.2 Hz, 4H), 7.12 (ddd, J¼8.1, 6.8,
1.3 Hz, 4H), 7.02e6.94 (m, 4H), 4.18 (dt, J¼10.0, 4.0 Hz, 4H), 4.01 (td,
J¼9.9, 3.0 Hz, 4H), 2.94 (dt, J¼14.3, 3.3 Hz, 4H), 2.70e2.64 (ddd,
J¼14.0, 9.8, 3.8 Hz, 4H). 13C NMR (75 MHz, CD2Cl2, ppm):
d
154.45,
4.7. Synthesis of the TTF diamides (3)
134.62, 131.66, 129.75, 129.71, 128.36, 126.70, 125.49, 124.01, 119.87,
115.74, 110.12, 67.76, 67.07, 37.45. MS (MALDI-TOF) m/z 1008.02
(Mþ). Elem. Anal. Calcd for C54H40O4S8 (1009.41): C, 64.25; H, 3.99.
Found: C, 64.69; H, 4.08.
4.7.1. Synthesis of (R,S)-3. To a solution of the racemic TTF diester
(R,S)-2 (100 mg, 0.138 mmol) in THF(20 mL) is added an aqueous
solution of NH3 (25% solution, 5 mL) at rt. After stirring for 24 h, the
solvents are evaporated, the residue taken in THF, dried over
MgSO4, concentrated, and purified by chromatography on silica gel
(THF/CH2Cl2, 1:3). Recrystallisation from THF/pentane afforded the
racemic ortho diamide (R,S)-3 as a pale orange powder (86 mg,
4.5.3. Synthesis of (SS)-1. As described above for (RR)-1, starting
from the enantiopure 1,3-dithiole-2-one (S)-6 (0.25 g, 0.48 mmol)
in P(OMe)3 (5 mL), one obtains (SS)-1 as yellow crystals (160 mg,
20
75%). Mp 218e220 ꢀC. ½
a
d
ꢄ
ꢁ1014 (c 0.05, CH2Cl2). 1H NMR
90%). Mp 278 ꢀC. 1H NMR (300 MHz, DMSO, ppm):
d 8.31 (s, 2H,
Na
(300 MHz, CD2Cl2, ppm):
7.88 (d, J¼9.0 Hz, 4H), 7.80 (d, J¼8.0 Hz,
NH2), 8.07 (s, 2H, NH2), 8.01 (d, J¼9.1 Hz, 2H), 7.91 (d, J¼8.0 Hz, 2H),
7.55 (d, J¼9.1 Hz, 2H), 7.37e7.24 (m, 2H), 7.25e7.13 (m, 2H), 6.88 (d,
J¼8.4 Hz, 2H), 4.22e4 0.25 (m, 2H), 4.12e4.05 (m, 2H), 3.18e3.01
(m, 2H), 2.88e2.72 (m, 2H). 13C NMR (300 MHz, DMSO, ppm):
4H), 7.31 (d, J¼9.0 Hz, 4H), 7.27e7.19 (m, 4H), 7.15e7.08 (m, 4H),
6.98 (d, J¼8.5 Hz, 4H), 4.18 (dt, J¼9.8, 3.8 Hz, 4H), 4.00 (td, J¼9.9,
2.8 Hz, 4H), 2.93 (dt, J¼14.2, 3.1 Hz, 4H), 2.63 (ddd, J¼14.0, 9.8,
3.8 Hz, 4H). 13C NMR (75 MHz, CD2Cl2, ppm):
d
154.45, 134.60,
d 160.60, 153.76, 133.58, 133.24, 130.74, 129.29, 128.79, 127.97,
131.79, 129.76, 129.67, 128.38, 126.72, 125.48, 124.01, 119.76, 115.69,
110.13, 67.00, 37.50. Elem. Anal. Calcd for C54H40O4S8 (1009.41): C,
64.25; H, 3.99. Found: C, 63.63; H, 4.02.
126.27, 124.55, 123.37, 118.70, 115.71, 108.25, 107.71, 66.50, 36.58.
MS (MALDI-TOF) m/z 691.9 (Mþ). Elem. Anal. Calcd for
C32H24N2O4S6 (692.93): C, 55.47; H, 3.49; N, 4.04. Found: C, 55.41;
H, 3.68; N, 3.66.
4.6. Synthesis of the TTF diesters (2)
4.7.2. Synthesis of (R)-3. As described above for (R,S)-3, starting
from the enantiopure diester (R)-2 (100 mg, 0.138 mmol). Recrys-
tallisation from THF/pentane affordred the enantiopure diamide
4.6.1. Synthesis of (R,S)-2. A solution of the racemic 1,3-dithiole-
2-thione (R,S)-6 (100 mg, 0.186 mmol) and bis(carboxymethyl)-
1,3-dithiole-2-one 9 (233 mg, 5 equiv, 0.93 mmol) in P(OMe)3
(5 mL) is heated to 130 ꢀC for 4 h under Ar. After evaporation of
the phospite under vacuum, the residue is purified by chroma-
tography on silica gel (CH2Cl2/petrol ether, 2:1). Recrystallisation
from CH2Cl2/petrol ether afforded (R,S)-2 as red crystals (70 mg,
20
(R)-3 as orange microcrystals (86 mg, 90%). Mp 267e268 ꢀC. ½
ꢄ
a
Na
þ320 (c 0.05, CH2Cl2). 1H NMR (300 MHz, DMSO, ppm):
d 8.31 (s,
2H, NH2), 8.06 (s, 2H, NH2), 8.01 (d, J¼9.0 Hz, 2H), 7.92 (d, J¼8.0 Hz,
2H), 7.55 (d, J¼9.0 Hz, 2H), 7.30 (t, J¼7.3 Hz, 2H), 7.20 (t, J¼7.5 Hz,
2H), 6.88 (d, J¼8.4 Hz, 2H), 4.39e4.20 (m, 2H), 4.19e3.99 (m, 2H),
3.20e2.99 (m, 2H), 2.91e2.69 (m, 2H). 13C NMR (75 MHz, DMSO,
54%). Mp 235 ꢀC. 1H NMR (300 MHz, CDCl3, ppm):
d 7.95 (d,
J¼8.9 Hz, 2H), 7.87 (d, J¼8.0 Hz, 2H), 7.37 (d, J¼9.0 Hz, 2H), 7.32
ppm):
d 160.60, 153.76, 133.58, 133.24, 130.73, 129.29, 128.79,
(ddd, J¼8.0, 6.7, 1.3 Hz, 2H), 7.22 (ddd, J¼8.0, 6.7, 1.3 Hz, 2H), 7.13
127.97, 126.27, 124.55, 123.37, 118.71, 115.71, 108.24, 107.72, 66.50,

A. Saad et al. / Tetrahedron 67 (2011) 3820e3829
3827
36.57. MS (MALDI-TOF) m/z 691.9 (Mþ). Elem. Anal. Calcd for
4.9. Synthesis of the EDT/TTF derivatives (5)
C32H24N2O4S6 (692.93): C, 55.47; H, 3.49; N, 4.04. Found: C, 55.35;
H, 3.66; N, 3.75.
4.9.1. Synthesis of (R,S)-5. A solution of the racemic 1,3-dithiole-2-
thione (R,S)-6 (0.15 g, 0.279 mmol) and EDT-substituted 1,3-
dithiole-2-one 10 (0.3 g, 5 equiv, 1.44 mmol) in P(OMe)3 (5 mL) is
stirred at 130 ꢀC for 5 h under Ar. After cooling to rt, the precipitated
BEDT/TTF is filtered and the evaporated filtrate purified by chro-
matography on silica gel (CH2Cl2/petrol ether 1:1). Recrystallisation
from CH2Cl2/ethanol afforded (R,S)-5 as a yellow powder (155 mg,
4.7.3. Synthesis of (S)-3. As described above for (R)-3, starting from
(S)-2 (150 mg, 0.207 mmol), one obtains (S)-3 as an orange cotton
20
(132 mg, 92%). Mp 262 ꢀC. ½
a
ꢄ
ꢁ324 (c 0.05, CH2Cl2). 1H NMR
Na
(300 MHz, DMSO, ppm):
d 8.33 (s, 2H, NH2), 8.09 (s, 2H, NH2), 8.01
(d, J¼9.1 Hz, 2H), 7.91 (d, J¼8.1 Hz, 2H), 7.55 (d, J¼9.1 Hz, 2H), 7.30 (t,
J¼7.4 Hz, 2H), 7.19 (t, J¼7.6 Hz, 2H), 6.88 (d, J¼8.4 Hz, 2H), 4.40e4.19
(m, 2H), 4.17e3.96 (m, 2H), 3.15e3.00 (m, 2H), 2.88e2.70 (m, 2H).
80%). Mp 175 ꢀC. 1H NMR (300 MHz, CD2Cl2, ppm):
d 7.87 (d,
J¼8.9 Hz, 2H), 7.79 (d, J¼8.1 Hz, 2H), 7.32 (d, J¼9.0 Hz, 2H), 7.24
(ddd, J¼8.1, 6.7, 1.2 Hz, 2H), 7.11 (ddd, J¼8.2, 6.7, 1.3 Hz, 2H),
7.01e6.94 (m, 2H), 4.18 (dt, J¼10.2, 4.1 Hz, 2H), 4.01 (td, J¼9.8,
3.1 Hz, 2H), 3.23 (s, 4H), 3.01e2.90 (m, 2H), 2.73e2.59 (m, 2H). 13C
13C NMR (75 MHz, DMSO, pm):
d 160.61, 153.75, 133.57, 133.24,
130.83, 129.29, 128.77, 127.98, 126.28, 124.55, 123.37, 118.65, 115.66,
108.28, 107.67, 66.44, 36.58. MS (MALDI-TOF) m/z 692 (Mþ). Elem.
Anal. Calcd for C32H24N2O4S6 (692.93): C, 55.47; H, 3.49; N, 4.04.
Found: C, 55.04; H, 3.41; N, 4.01.
NMR (75 MHz, CD2Cl2, ppm):
d 154.48, 134.58, 131.48, 129.77,
129.76, 128.37, 126.65, 125.44, 123.99, 119.95, 115.98, 114.30, 114.17,
108.64, 67.39, 37.50, 30.75. MS (MALDI-TOF) m/z 697.5 (Mþ). Elem.
Anal. Calcd for C32H24O2S8 (697.05): C, 55.14; H, 3.47. Found: C,
54.59; H, 3.41.
4.8. Synthesis of TTF (4)
4.8.1. Synthesis of (R,S)-4. To a solution of the racemic diester (R,S)-
2 (100 mg, 0.139 mmol) in HMPA (5 mL) is added LiBr (100 mg,
1.15 mmol) and the mixture is warmed to 145 ꢀC during 20 nm,
using a prealably heated oil bath. After rapid cooling, the solvent is
evaporated under vacuum, the residue is taken into H2O and
extracted with CH2Cl2 (3ꢃ). The organic phase is washed with H2O,
dried over MgSO4, and concentrated. Chromatography (silica gel,
CH2Cl2/petrol ether 1:1) and recrystallisation from CH2Cl2/petrol
ether afforded (R,S)-4 as yellow crystals (70 mg, 84%). Mp 191 ꢀC. 1H
4.9.2. Synthesis of (R)-5. As described above for (R,S)-5, using the
1,3-dithiole-2-thione (R)-6 (0.25 g, 0.46 mmol) and the dithiole-2-
one 10 (0.5 g, 5 equiv, 2.4 mmol) afforded (R)-5 as yellow crystals
20
(0.27 g, 85%). Mp 170 ꢀC. ½
a
ꢄ
þ770 (c 0.05, CH2Cl2). 1H NMR
Na
(300 MHz, CD2Cl2, ppm):
d
7.85 (d, J¼9.0 Hz, 2H), 7.77 (d, J¼8.1 Hz,
2H), 7.29 (d, J¼9.0 Hz, 2H), 7.22 (ddd, J¼8.1, 6.8, 1.2 Hz, 2H), 7.10
(ddd, J¼8.1, 6.7, 1.3 Hz, 2H), 6.97 (d, J¼8.0 Hz, 2H), 4.14 (dt, J¼10.1,
4.0 Hz, 2H), 3.99 (td, J¼9.8, 3.1 Hz, 2H), 3.19 (s, 4H), 2.92 (dt, J¼7.1,
3.3 Hz, 2H), 2.70e2.55 (m, 2H). 13C (75 MHz, CD2Cl2, ppm):
d 154.49,
NMR (300 MHz, CD2Cl2, ppm):
d
7.88 (d, J¼9.0 Hz, 2H), 7.79 (d,
134.60, 131.57, 129.80, 129.75, 128.40, 126.68, 125.47, 124.01, 119.93,
115.96, 114.31, 114.21, 108.63, 67.35, 37.52, 30.76. MS (MALDI-TOF)
m/z 697 (Mþ). Elem. Anal. Calcd for C32H24O2S8 (697.05): C, 55.14; H,
3.47. Found: C, 54.73; H, 3.34.
J¼8.1 Hz, 2H), 7.32 (d, J¼9.0 Hz, 2H), 7.23 (ddd, J¼8.1, 6.8,1.2 Hz, 2H),
7.11 (ddd, J¼8.1, 6.7, 1.3 Hz, 2H), 6.98 (d, J¼8.0 Hz, 2H), 6.28 (s, 2H),
4.19 (dt, J¼10.1, 4.1 Hz, 2H), 4.02 (td, J¼9.8, 3.1 Hz, 2H), 3.03e2.86
(m, 2H), 2.74e2.54 (m, 2H). 13C NMR (75 MHz, CD2Cl2, ppm):
d
154.51, 134.60, 131.61, 129.75, 128.35, 126.65, 125.46, 123.98,
4.9.3. Synthesis of (S)-5. As described above for (R,S)-5. Using the
enantiopure 1,3-dithiole-2-thione (S)-6 (0.25 g, 0.46 mmol) and the
dithiole-2-one 10 (0.5 g, 5 equiv, 2.4 mmol) afforded (S)-5 as yellow
119.92, 119.41, 115.95, 114.98, 105.93, 67.31, 37.42. MS (MALDI-TOF)
m/z 605.5 (Mþ). Elem. Anal. Calcd for C30H22O2S6 (606.88): C, 59.37;
H, 3.65. Found: C, 59.24; H, 3.68.
20
crystals (0.27 g, 85%). Mp 171e172 ꢀC. ½
a
ꢄ
ꢁ764 (c 0.05, CH2Cl2). 1H
Na
NMR (300 MHz, CD2Cl2, ppm):
d
7.99 (d, J¼8.9 Hz, 2H), 7.91 (d,
4.8.2. Synthesis of (R)-4. As described above for (R,S)-4, starting
from the enantiopure diester (R)-2 (100 mg, 0.139 mmol), one ob-
J¼8.1 Hz, 2H), 7.43 (d, J¼9.0 Hz, 2H), 7.36 (ddd, J¼8.1, 6.7,1.3 Hz, 2H),
7.24 (ddd, J¼8.1, 6.7, 1.3 Hz, 2H), 7.13e7.07 (m, 2H), 4.28 (dt, J¼10.1,
4.0 Hz, 2H), 4.12 (td, J¼9.9, 3.1 Hz, 2H), 3.34 (s, 4H), 2.92 (dt, J¼7.1,
3.3 Hz, 2H), 2.83e2.70 (m, 2H). 13C NMR (75 MHz, CD2Cl2, ppm):
tains after chromatography (R)-4 as a yellow powder (70 mg, 84%).
20
Mp 148 ꢀC. ½
a
ꢄ
þ790 (c 0.05, CH2Cl2). 1H NMR (300 MHz, CD2Cl2,
Na
ppm):
d
7.88 (d, J¼9.0 Hz, 2H), 7.79 (d, J¼8.1 Hz, 2H), 7.32 (d,
d 154.48, 134.58, 131.62, 129.80, 129.73, 128.41, 126.69, 125.46,
J¼9.0 Hz, 2H), 7.23 (ddd, J¼8.1, 6.8, 1.2 Hz, 2H), 7.12 (ddd, J¼8.1, 6.7,
1.3 Hz, 2H), 6.98 (d, J¼8.1 Hz, 2H), 6.28 (s, 2H), 4.19 (dt, J¼10.1,
4.1 Hz, 2H), 4.02 (td, J¼9.8, 3.1 Hz, 2H), 3.03e2.89 (m, 2H),
124.01, 119.87, 115.94, 114.26, 108.59, 67.31, 37.54, 30.74. MS
(MALDI-TOF) m/z 697.4 (Mþ). Elem. Anal. Calcd for C32H24O2S8
(697.05): C, 55.14; H, 3.47. Found: C, 55.02; H, 3.41.
2.74e2.58 (m, 2H). 13C NMR (75 MHz, CD2Cl2, ppm):
d 154.50,
154.50, 134.60, 131.61, 129.75, 129.73, 128.35, 126.65, 125.46, 123.97,
119.91, 119.41, 115.95, 114.97, 67.31, 37.41. MS (MALDI-TOF) m/z
605.7 (Mþ). Elem. Anal. Calcd for C30H22O2S6 (606.88): C, 59.37; H,
3.65. Found: C, 59.06; H, 3.78.
4.10. The charge-transfer compounds of (R,S)-5 with TCNQ
and TCNQF4
With TCNQ. TCNQ (6 mg, 0.029 mmol) is added to a warm so-
lution of the racemic donor (R,S)-5 (10 mg, 0.0143 mmol) in CH3CN
(10 mL). The cooled solution deposited black crystals after 2 days.
Filtration and washing with CH3CN afforded the title compound
(12 mg, 89%), a 1:1 complex formulated as [(R,S)-5](TCNQ)$CH3CN
4.8.3. Synthesis of (S)-4. As described above for (R,S)-4, starting
from the enantiopure diester (S)-2 (150 mg, 0.207 mmol), one ob-
tains after chromatography (S)-4 as a yellow powder (107 mg, 85%).
20
Mp 145 ꢀC. ½
a
ꢄ
ꢁ794 (c 0.05, CH2Cl2). 1H NMR (300 MHz, CD2Cl2,
Na
ppm):
d
8.00 (d, J¼9.0 Hz, 2H), 7.91 (d, J¼8.1 Hz, 2H), 7.44 (d,
from single crystal X-ray diffraction. IR: nC^
2202 cmꢁ1. Elem.
N
J¼9.0 Hz, 2H), 7.36 (ddd, J¼8.1, 6.8, 1.2 Hz, 2H), 7.24 (ddd, J¼8.1, 6.8,
1.3 Hz, 2H), 7.11 (d, J¼8.1 Hz, 2H), 6.40 (s, 2H), 4.30 (dt, J¼10.1,
4.0 Hz, 2H), 4.13 (td, J¼9.9, 3.0 Hz, 2H), 3.08 (dt, J¼14.4, 3.5 Hz, 2H),
Anal. Calcd for C46H31N5O2S8 (942.31 g molꢁ1): C, 58.63; H, 3.32; N,
7.43. Found: C, 58.42; H, 3.15; N, 6.96.
With TCNQF4. TCNQF4 (10 mg, 0.036 mmol) is added to a warm
solution of the racemic donor (R,S)-5 (15 mg, 0.0215 mmol) in
CH3CN (15 mL). The cooled solution deposited black crystals after 2
days. Filtration and washing with CH3CN afforded the title com-
2.85e2.68 (m, 2H). 13C NMR (75 MHz, CD2Cl2, ppm):
d 154.51,
134.60, 131.71, 129.77, 129.71, 128.38, 126.68, 125.46, 123.99, 119.85,
119.44, 115.92, 67.26, 37.45. MS (MALDI-TOF) m/z 605.7 (Mþ). Elem.
Anal. Calcd for C30H22O2S6 (606.88): C, 59.37; H, 3.65. Found: C,
59.41; H, 3.58.
pound (18 mg, 79%),
a 1:1 complex formulated as [(R,S)-
5](TCNQF4)$(CH3CN)2 from single crystal X-ray diffraction. IR: nC
^
N

3828
A. Saad et al. / Tetrahedron 67 (2011) 3820e3829
2191, 2165 cmꢁ1
.
Elem. Anal. Calcd for C44H24F4N4O2S8
Crystallographic data (excluding structure factors) for the
structures in this paper have been deposited with the Cambridge
Crystallographic Data Centre as supplementary publication num-
bers CCDC 815024e815031. Copies of the data can be obtained, free
of charge, on application to CCDC, 12 Union Road, Cambridge CB2
1EZ, UK [fax: 44(0) 1223 336033 or email: deposit@ccdc.cam.ac.uk].
(973.20 g molꢁ1): C, 54.30; H, 2.49. Found: C, 52.99; H, 2.41.
4.11. Crystallography
Data were collected on a APEX II Brucker AXS diffractometer
ꢁ
with Mo K
a
radiation (
l
¼0.71073 A). Structures were solved by
direct methods (SHELXS97)30 and refined (SHELXL-97)30 by full-
matrix least-squares methods as implemented in the WinGX soft-
ware package.31 An empirical absorption (multi-scan) correction
was applied. Hydrogen atoms were introduced at calculated posi-
tions (riding model) included in structure factor calculation but not
refined. A pentane molecule included in the structure of (RR)-1 and
(SS)-1 was properly refined in the latter while an SQUEEZE pro-
cedure had to be used in the (RR) isomer. The crystals of the TCNQ
complex [(R,S)-5]TCNQ$CH3CN was twinned. CELLNOW was used
to determine the orientation matrices of both components and
TWINABS for absorption correction (see details in cif file) (Table 3).
Acknowledgements
Financial support from ANR (Paris) under grant number no ANR-
BLAN08-3_317277 is gratefully acknowledged. We also thank T.H.
Roisnel at CDIFX (Rennes) for access to the X-ray diffractometers.
Supplementary data
Cyclic voltamogramm for all newly prepared TTF derivatives
(Figs. S1e5), circular dichroism spectra for pairs of enantiomers,
(RR)-1 and (SS)-1, (R)-2, and (S)-2, (R)-3 and (S)-3, (R)-4, and (S)-4,
Table 3
Crystallographic data
(RR)-1,Pentane
(SS)-1,Pentane
(R,S)-2
(R,S)-4
Formula
C59H52O4S8
1081.49
Monoclinic
C2
100 (2)
39.3170 (11)
8.2662 (2)
8.2330 (2)
90.0
96.7880 (10)
90.0
2656.99 (12)
2
1.352
0.384
12569
4620
0.0227
4515
299
0.0264
C59H52O4S8
1081.57
Monoclinic
C2
150 (2)
39.2936 (17)
8.3191 (3)
8.2604 (4)
90.0
96.4540 (10)
90.0
2683.1 (2)
2
1.339
0.380
10805
5399
0.0312
4763
316
0.0400
0.1178
0.02 (7)
0.70, ꢁ0.35
C34H26O6S6
722.91
Triclinic
Pꢁ1
C30H22O2S6
606.84
Triclinic
Pꢁ1
Formula mass
Crystal system
Space group
T (K)
100 (2)
8.0349 (10)
13.0347 (15)
15.7987 (19)
79.400 (4)
81.871 (4)
82.790 (4)
1601.6 (3)
2
293 (2)
7.9067 (2)
12.8042 (3)
14.8200 (4)
73.164 (2)
79.895 (2)
87.640 (3)
1413.70 (6)
2
ꢁ
a/A
ꢁ
b/A
ꢁ
c/A
a
/degrees
/degrees
b
g
/degrees
3
ꢁ
V/A
Z
dcalc/g cmꢁ3
1.499
0.474
13024
7819
0.0221
6637
417
0.0325
1.426
0.512
30896
6479
0.0302
4961
389
0.0321
1
m
/mmꢁ
Data collected
Ind. data
Rint
Obs data (I>2
Param. refined
R(F)
s
(I))
wR(F2)
0.0756
0.02 (5)
0.45, ꢁ0.31
0.1134
d
0.0876
d
Flack param.
Residual d/e A
ꢁꢁ3
0.49, ꢁ0.45
0.19, ꢁ0.28
(R)-5$CH2Cl2
(S)-5$CH2Cl2
[(R,S)-5)] TCNQ$CH3CN
[(R,S)-5] TCNQF4$(CH3CN)2
Formula
C33H26Cl2O2S8
781.92
C33H26Cl2O2S8
781.92
C46H31N5O2S8
942.24
C48H30F4N6O2S8
1055.26
Triclinic
Pꢁ1
Formula mass
Crystal system
Space group
T (K)
Orthorhombic
P212121
100 (2)
7.5235 (3)
19.4669 (7)
46.2483 (17)
90.0
90.0
90.0
6773.5 (4)
8
1.534
Orthorhombic
P212121
150 (2)
7.5531 (2)
19.5746 (5)
46.2788 (11)
90.0
90.0
90.0
6842.3 (3)
8
1.518
Triclinic
Pꢁ1
150 (2)
150 (2)
9.0865 (10)
11.0459 (13)
23.991 (3)
100.389 (3)
100.027 (3)
93.823 (3)
2320.4 (5)
2
ꢁ
a/A
7.4318 (11)
13.938 (2)
22.315 (4)
73.395 (7)
86.882 (8)
74.699 (7)
2136.0 (6)
2
ꢁ
b/A
ꢁ
c/A
a/degrees
b/degrees
g
/degrees
3
ꢁ
V/A
Z
dcalc/g cmꢁ3
1.465
0.465
1.510
0.450
m
/mmꢁ1
0.717
0.710
Data collected
Ind. data
Rint
73890
15549
0.0520
63687
15587
0.0390
25778
19369
10226
0.0368
11183
a
Obs data (I>2
Param. refined
R(F)
s
(I))
14142
811
0.0386
0.1002
14285
811
0.0295
0.0975
3952
552
0.0717
0.2337
d
6388
615
0.0487
0.1604
d
wR(F2)
Flack param.
Residual d/e A
ꢁ0.02 (4)
ꢁ0.02 (4)
ꢁꢁ3
0.38, ꢁ0.43
0.45, ꢁ0.37
0.55, ꢁ0.59
0.59, ꢁ0.55
a
Twinned crystal. See text and cif file.

A. Saad et al. / Tetrahedron 67 (2011) 3820e3829
3829
ꢀ
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