Chiroptical properties of 1,3-diphenylallene-anchored tetrathiafulvalene and its polymer synthesis

Article abstract of DOI:10.3762/bjoc.11.109

A novel tetrathiafulvalene dimer, bridged by a chiral 1,3-diphenylallene framework, has been prepared as an optically active compound having strong chiroptical properties. Although a chiral allene bearing strong electron-donating group(s) often undergoes slow photoracemization even in daylight, the present allene is totally configurationally stable under ordinary conditions. Each isomer possesses pronounced chiroptical properties in its ECD spectra reflecting the chiral allene framework. Moreover, the elongation of the chiral main chain was also carried out by direct C-H activation of the TTF unit, and the chiroptical properties of the resulting polymer were also investigated.

Full text of DOI:10.3762/bjoc.11.109

Chiroptical properties of 1,3-diphenylallene-anchored
tetrathiafulvalene and its polymer synthesis
Masashi Hasegawa*1, Junta Endo1, Seiya Iwata1, Toshiaki Shimasaki2
and Yasuhiro Mazaki*1
Full Research Paper
Open Access
Address:
Department of Chemistry, School of Science, Kitasato University,
-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa 252-0373, Japan
and 2Graduate School of Engineering, Chiba Institute of Technology,
-17-1 Tsudanuma, Narashino, Chiba 275-0016, Japan
Beilstein J. Org. Chem. 2015, 11, 972–979.
1
doi:10.3762/bjoc.11.109
1
Received: 23 February 2015
Accepted: 13 May 2015
Published: 08 June 2015
2
Email:
Masashi Hasegawa* - masasi.h@kitastato-u.ac.jp; Yasuhiro Mazaki* -
mazaki@kitasato-u.ac.jp
This article is part of the Thematic Series "Tetrathiafulvalene chemistry".
Guest Editor: P. J. Skabara
*
Corresponding author
©
2015 Hasegawa et al; licensee Beilstein-Institut.
Keywords:
License and terms: see end of document.
allene; axial chirality; chiroptical properties; redox; tetrathiafulvalene
Abstract
A novel tetrathiafulvalene dimer, bridged by a chiral 1,3-diphenylallene framework, has been prepared as an optically active com-
pound having strong chiroptical properties. Although a chiral allene bearing strong electron-donating group(s) often undergoes slow
photoracemization even in daylight, the present allene is totally configurationally stable under ordinary conditions. Each isomer
possesses pronounced chiroptical properties in its ECD spectra reflecting the chiral allene framework. Moreover, the elongation of
the chiral main chain was also carried out by direct C–H activation of the TTF unit, and the chiroptical properties of the resulting
polymer were also investigated.
Introduction
Recently, there has been a growing interest in chiral π-conju- A symmetric allene framework is one of the most reliable chiral
gated systems having strong chiroptical properties because they resources that can preserve a consistent orientation of the chro-
have great potential for use in optical devices involving polar- mophores [8,9]. We recently introduced 1,3-bis(tetrathiaful-
ized light [1-3]. Chiral response, in electronic circular dichroism valenyl)allene derivatives 1, as a new class of chiral elec-
(
ECD) based on an exciton coupling between two adequate trochromic (EC) materials consisting of redox-active chro-
π-chromophores, can express a pronounced chiroptical effect mophores and a non-centrochiral framework (Figure 1) [10].
over various optical energy regions. Therefore, embedding the The intensive Cotton effect on the ECD spectra is switchable by
chromophores into a chiral rigid framework can be a practical tuning the electronic structure of the tetrathiafulvalene (TTF)
molecular design for ascertaining chiroptical materials [4-7].
moieties. However, compound 1 exhibited slow racemization in
972

Beilstein J. Org. Chem. 2015, 11, 972–979.
dissymmetric allene having a TTF and a pyrenyl group at 1,3-
position, suggests that the direct connection of the TTF units
may strongly affect the fast racemization [14]. From this point
of view, we decided to employ a 1,3-diphenylallene derivative
(
3) as a stable chiral framework. We conceive that the insertion
of the phenylene units between the central chiral allene and
TTFs would overcome the vulnerability toward the photoracem-
ization under ambient conditions. Previsously, Krause and
co-workers reported the first synthesis of a cyclic allenophane
involving a racemic 1,3-diphenyl allene unit [15]. In addition,
Fallis and co-workers synthesized a cyclic oligoallene based on
a chiral 1,3-diphenylallene [16]. More recently, Kijima and
co-workers reported the use of a racemic 1,3-diphenylallene
framework as a new building block for a π-conjugated polymer
[
17]. However, there have been few investigations regarding the
use of 1,3-diphenylallene as a chiral source and involving the
detailed investigations of the chiroptical property. In this paper,
we report the synthesis of chiral 1,3-bis(4-(tetrathiafulvale-
nenyl)phenyl)allene derivative 3 and its chiroptical properties.
Furthermore, the first synthesis of a chiral copolymer
containing TTFs based on a chiral allenic framework (poly-3:
PTDPA is also demonstrated.
Figure 1: TTF-substituted allenes 1–3.
Results and Discussion
To anchor the TTF groups into the allene framework, we chose
solution under daylight. The chirality of an allene is configura- a cross-coupling reaction of unknown 1,3-bis(4-iodophenyl)-
tionally firm in general, because the barrier of the rotation of the 1,3-diisopropylallene (9) with a TTF-zinc intermediate
allenic double bonds is quite high (ΔG‡ = 180 kJ mol−1 for (Scheme 1). Previously, 1,3-bis(2-bromophenyl)allene deriva-
CH3CH=C=CHCH3) [11]. In contrast, several allenes directly tives were reported by Ready et al. as a precursor of an asym-
connected with electron-donating groups occasionally under- metric catalyst [18]. To obtain the chiral 1,3-bis(4-bromo-
went photoracemization [12,13]. Although the mechanism of phenyl)allene (8) in a larger scale, we modified the synthesis
the photoracemization is not clear, a comparative examination and the chiral separation process as shown in Scheme 1. Thus,
of the racemization rate in 1 and 2, the latter of which is a starting with 1-(4-bromophenyl)-2-methylpropanone (4), which
Scheme 1: Synthesis of 3.
973

Beilstein J. Org. Chem. 2015, 11, 972–979.
was prepared from bromobenzaldehyde (see Supporting Infor-
mation File 1), which upon treatment with lithium acetylide at
low temperature gave racemic propargyl alcohol 5 in 94% yield.
Sonogashira coupling reaction of 5 with 4-bromoiodobenzene
gave compound 6 quantitatively. The treatment of 6 with Ac2O
and a catalytic amount of N,N-dimethyl-4-aminopyridine
(
DMAP) gave the acetyl ester 7 in 93% yield. The formation of
,3-bis(4-bromophenyl)-1,3-diisopropylallene (8) was achieved
1
by an SN2’-type reaction of 7 with iPrMgCl–CuI–LiBr at low
temperature in 90% yield. This allene was easily transformed
into the precursor 9 by halogen exchange with t-BuLi followed
by the addition of C6F13I in 92% yield. Subsequently, the reac-
tion of the diiodo precursor 9 with 2 equiv of an organozinc
species derived from 4,5-bis(methylthio)TTF [19] in the pres-
ence of Pd(PPh3)4 gave racemic compound 3 in good yield
(
89%). In the 13C NMR spectrum, the allenic =C= carbon was
found to be at 204 ppm, which is a typical value of the linear
allene framework. In addition, the FTIR spectrum also exhib-
ited a reasonable vibrational stretching of the C=C=C unit at
1
914 cm−1.
Because new symmetrical allenes were subject to optical resolu-
tion, the separation of (rac)-3 was carried out by using a recy-
cling HPLC method on a chiral stationary phase (DAICEL
Chiralpak IA-3) with hexane/CHCl3/EtOH (v/v = 20:10:0.2)
elution. Thus, equimolecular amounts of the optically pure
allenes (+)-3 and (−)-3, whose optical rotations ([α]D25) are
Figure 2: (a) ECD spectra of (R)-(−)-3 (3.5 × 10−5 M), (S)-(+)-3
(3.8 × 10−5 M), (R)-(−)-9 (3.0 × 10−5 M), and (S)-(+)-9 (2.9 × 10−5 M) in
CH2Cl2 together with the simulated ECD spectra of 3 and 9 in (R)-con-
figuration. (b) UV spectra of 3 (3.5 × 10−5 M) and 9 (3.8 × 10−5 M) in
CH2Cl2.
+
726 (c 0.853 in CH2Cl2) and −721(c 0.853 in CH2Cl2), res-
pectively, were collected. Similarly, optical resolution of (rac)-
also provided (+)/(−)-9 with optical rotations ([α]D25) of +338 by TD-DFT (B3LYP/6-31G(d,p)), has moderate resemblance to
9
(
c 0.83 in CH2Cl2) and −341 (c 0.83 in CH2Cl2), respectively.
the spectrum obtained from (−)-3. This result is also consistent
with the hypothesis from the chiral exciton coupling method. To
Figure 2 depicted the electronic circular dichroism (ECD) solidify the absolute configuration, the synthesis of (R)-3 from
spectra of the enantiomers of (+)/(−)-3 and (+)/(−)-9, and their (R)-9 was carried out separately, and the ECD spectrum of the
UV–vis absorption spectra. The ECD spectrum of the (−)-9 product from (R)-3 was in complete accord with that of (−)-9.
enantiomer exhibited a clear bisignate CD curve with a nega- Therefore, the absolute configuration of (+)-3 and (−)-3 should
tive peak at 274 nm and a positive peak at 248 nm. According be (+)-(S)-3 and (−)-(R)-3, respectively. In the spectra, the
to the chiral exciton coupling method [20], the spectrum trend intensive Cotton effect was observed at 270 and 316 nm as a
of (−)-9 suggests that the isomer should have the (R)-configur- bisignate couple, together with broad shoulder tails to ca.
ation. This assignment was also validated by spectral simula- 500 nm. The Cotton effect associated with the HOMO–LUMO
tion, obtained from the electronic transition energies and the transition was relatively weak, presumably due to the long-
rotational strengths using TD-DFT calculations [21]. Thus, the range coupling between two TTF units in the chiral situation.
intensive Cotton effect is associated with the exciton coupling Although allenes 1 and 2, reported previously, underwent quick
of the two chromophores of the iodobenzene units. In the ECD photoracemization, the present allenes, 3 and 9, exhibit photo-
spectrum of (+)-9, the mirror image of the trend lines of (−)-9 chemical stability without racemization in common organic
was found.
solvents. It clearly suggests that the insertion of the phenylene
units effectively prevents racemization.
The UV–vis absorption spectrum of 3 exhibits absorption
maxima at 314 and 405 nm. In the ECD spectra of (+)/(−)-3, the To examine the potential of the 1,3-diphenylallene frameworks
Cotton effect was observed over the entire absorption range. A as a stable chiral resource, a chiral alternate copolymer
simulated spectrum of 3 with the (R)-configuration, calculated consisting of TTF and chiral diphenylallene (PTDPA) was
974

Beilstein J. Org. Chem. 2015, 11, 972–979.
prepared, and its chiroptical properties were investigated. Previ- there is not any amplification owing to a higher order structure
ously, a racemic conjugated polymer in the literature was in the polymer. Moreover, the ECD intensities of both enan-
prepared by a Suzuki–Miyaura or Yamamoto coupling reaction tiomers did not change under ambient light, at least over several
from (rac)-8 [17]. In contrast, to the best of our knowledge, days. Therefore, 1,3-diphenylallene is a reliable chiral source
there is no example of a chiral polymer based on the 1,3-di- for a chiral polymer having electron-donating units.
phenylallene frameworks that can be a unit of copolymer with
various types of aryl groups. At this point, we have chosen the
direct arylation of TTF in the presence of a palladium catalyst
as a key reaction for the chiral polymer synthesis (Scheme 2)
[
22]. Thus, the chiral allenes, (R)-9 or (S)-9, react with an active
palladium species, prepared in situ from Pd(OAc)2 and
P(t-Bu)3·HBF4 salt in the presence of CsCO3, to give the chiral
copolymer of (R)-PTDPA and (S)-PTDPA, respectively, after
purification by column chromatography on polystyrene Bio-
beads. By using gel permeation chromatography (GPC), the
number-average molecular weights (Mn) of the collected
PTDPA were in the range of 2800–5600 g mol−1 with polydis-
persity index (PDI) values between 1.01–1.54. These polymers
solubilized well in common organic solvents, and they were
characterized by their NMR spectra.
Figure 3 depicts normalized UV–vis absorption and ECD
spectra of (R)-PTDPA and (S)-PTDPA, together with (R)-3 and
(
S)-3. The polymer exhibited absorption maxima at 310 nm and
shoulder absorption at ca. 415 nm, extending up to 600 nm. The
shape of the spectrum is quite similar to that of the monomer 3.
The ECD spectra of both enantiomeric polymers exhibited the
mirror image. There are two intensive Cotton effects at 318 nm
(
λfirst) and 254 nm (λsecond), together with a weak ellipticity in
the range of ca. 360–450 nm. The shape of the trend line of
PTDPA is similar to that of 3 with the same absolute configur-
ation at the allenic moiety except for the small blue shift of the
λsecond value of PTDPA (254 nm). Consequently, the chiral
situation of the chromophores is preserved in the polymeric
structure. However, the Cotton effect associated with the TTF
moieties was observed as a relatively weak band, and hence
Figure 3: (a) UV–vis absorption spectra of 3 and PTDTA in CH2Cl2.
(b) Normalized ECD spectra of (R)-PTDPA, (S)-PTDPA, (R)-3, and
(S)-3 in CH2Cl2.
Scheme 2: Synthesis of chiral (R)-PTDPA and (S)-PTDPA.
975

Beilstein J. Org. Chem. 2015, 11, 972–979.
The electrochemical properties of 3 and PTDPA were investi-
gated by cyclic voltammetry (CV) analyses (Figure 4 and
Table 1). In CVs, there are two sets of reversible redox waves in
the conventional potential range. Compound 3 exhibits
two two-electron transfer waves at E11/2 = −0.01 V and
E21/2 = 0.31 V, whereas PTDPA exhibits in a similar manner at
E11/2 = 0.03 V and E21/2 = 0.30 V. These results suggest that
the TTF units in both compounds are oxidized independently to
form TTF/TTF•+ and, subsequently, TTF•+/TTF2+. A small
positive shift of E11/2 in PTDPA is presumably due to the
substituent effects of the two phenylene groups in the TTF unit.
Figure 4: CV of 3 (7.8 × 10−4 M) and PTDPA in PhCN.
Table 1: Redox potentials of 3 and PTDPA.a
Figure 5: Electronic spectra of (a) 3 and its cationic species, and
Compound
E11/2
E21/2
(b) PTDPA and its cationic states of PTDPA-(+1) and PTDPA-(+2).
3
−0.01
0.31
0.30
PTDPA
0.03
the SOMO in the TTF•+ moieties. The value was slightly red-
shifted compared with that of 10•+ (775 nm). This small
bathochromic shift can be ascribed to the conjugation to the
central allene moiety. As for the spectrum of 34+, the absorp-
tion maximum at 667 nm, assigned to the HOMO–LUMO tran-
aIn PhCN containing 0.1 M n-Bu4ClO4 at 25 °C. Potentials were
measured against an Ag/Ag+ electrode and adjusted to the Fc/Fc+
potential under identical conditions.
To investigate the electronic structures of 3 in various redox sition in the TTF2+ moieties, was also red-shifted compared
states, cationic species of 32+ and 34+ were prepared by their with the corresponding absorption maximum (637 nm) of 102+.
reaction with an adequate amount of Fe(ClO4)3, as the oxidant,
in a MeCN/CH2Cl2 (v/v = 1:4) solution (Figure 5a). During the Similarly, cationic species of PTDPA were also produced by the
sequential addition of between 0 to 2 equivalents of the oxidant, sequential addition of Fe(ClO4)3 (Figure 5b). During the oxi-
no isosbestic point was seen other than that of 3/32+. Therefore, dation, three phases of PTDPA-(0), PTDPA-(+1), and PTDPA-
3
2+ was formed first other than 3•+, suggesting that there is few (+2), corresponding to the oxidation stages involving TTF,
intramolecular interactions between two TTF units through the TTF•+, and TTF2+, respectively, were observed during the oxi-
central 1,3-diphenylallene moiety. The obtained spectrum of dation. The spectrum of the intermediate phase of PTDPA-(+1)
3
2+ is quite similar to those of 4,5-bis(methylthio)tetrathiaful- having absorption maxima at 459 and 816 nm are almost coinci-
valenylbenzene radical cation 10•+, which was reported previ- dent with that of 32+ (Table 2). With excess addition of the
ously [7] (Table 2). In the spectrum of 32+, the absorption oxidant, the third phase of PTDPA-(+2) appeared, and the spec-
maximum at 810 nm is assigned to an electronic transition to trum was almost identical to 34+. The spectral resemblance
976

Beilstein J. Org. Chem. 2015, 11, 972–979.
Although the observed Cotton effect associated with TTF
moieties is relatively weak, each chiral allene is stable towards
the racemization under ambient light. A chiral copolymer based
on TTF and a chiral 1,3-diphenylallene as the main chain scaf-
fold (PTDPA) was also prepared using a direct C–H activation
of the TTF framework. The resultant chiral polymers exhibited
the characteristic Cotton effect associated with the central chiral
Table 2: Absorption maxima of 3, 10 and PTDPA.a
Compound
λmax
3
313 (66600), 405 (11900)
3
13 (41100), 412 (17500), 466
32+
(22300), 810 (19700)
3
1
1
1
4+
313 (43900), 667 (34600)
332 (14800), 393 (3900)
256 (18300), 449 (11200), 775 (8100)
259 (21500), 646 (17900)
309, 410
0b
1
,3-diphenylallene moieties. The polymer also did not undergo
0•+ b
02+ b
racemization under daylight. Moreover, electrochemical prop-
erties were also investigated by the CV method. Cationic
species were prepared by the addition of Fe(ClO4)3 as the
oxidant, and their UV and ECD spectra were also recorded.
Other molecular designs, including a copolymer based on the
1,3-diphenylallene units, are currently underway to create valu-
able chiral molecules.
PTDPA-(0)
PTDPA-(+1)
PTDPA-(+2)
459, 816
667
aConditions: in CH2Cl2-MeCN (v/v = 4:1) solution at 25 °C. The molec-
ular structure of 10 is depicted as follow:
Experimental
4
,5-Bis(methylthio)TTF was prepared according to literature
bData from [7].
procedures [19]. Dehydrated THF and Et2O were purchased
from Wako Pure Chemical Industries, LTd. (Super Dehydrated,
implies that the influence of the central 1,3-diphenylallene on Stabilizer Free, H2O < 10ppm). Anhydrous ZnCl2 (99%) was
the electronic structure of the TTF units in PTDPA is quite purchased from Wako Pure Chemical Industries, and dried in
small.
vacuo for 4 h with heating over 220 °C. Other commercially
available materials were used as received. Column chromatog-
Finally, the ECD spectra of these cation species of 3 and raphy was carried out using Kanto chemical silica gel 60N,
PTDPA were measured (Supporting Information File 1, Figure 60–210 μm meshes. 1H and 13C NMR spectra were recorded on
S15). Contrary to the absorption spectra, there is no distinctive Bruker AVANCE-III-400 (400 MHz for 1H, 100 MHz for 13C)
ellipticity based on the cationic species of TTF in any cationic or on Bruker AVANCE-III-600 (600 MHz for 1H, 150 MHz for
species derived from 3 or PTDPA. Only small changes of λfirst 13C). Spectra are reported (in δ) referenced to internal Me4Si.
and λsecond peaks, mainly associated with the 1,3-diphenyl- Mass spectra were recorded on Thermo Scientific, Exactive
allene framework, were observed during the oxidation reac- Plus Orbitrap Mass Spectrometer with atmospheric pressure
tions. In the present chiral system, the chiroptical effects chemical ionization (APCI) probe. IR spectra were recorded on
between two TTF units are small due to the long-range exciton JASCO FT/IR-610 spectrometer. Melting points were deter-
coupling, and hence the Cotton effect derived from the elec- mined with Yanaco melting point apparatus. Elemental analyses
tronic transition of the TTF moiety was not clearly seen. were performed on Perkin Elmer PE 2400-II CHNA/O
However, both chiral compounds of 3 and PTDPA did not analyzer. Optical resolution was carried out with recyclable
undergo the racemization in daylight. Therefore, the chirality preparative HPLC (JAI Model LC-9204) equipped with Daicel
was also preserved in the cationic species.
CHIRALPAK-IA3 column (20 Ø × 250 mm). The optical rota-
tions were measured with JASCO P-1300 spectropolarimeter in
1 dm quartz cell at 24 °C. Electronic circular dichroism (ECD)
Conclusion
In this paper, we have shown the synthesis and chiroptical prop- spectra were recorded on JASCO J-725 spectrodichrometer.
erties of a novel chiral TTF dimer linked by a 1,3-diphenyl- The spectra were combined after the baseline correction of each
allene framework for the purpose of the development of a stable measurement. cyclic voltammetry (CV) measurements were
chiral source without racemization under ambient conditions. performed on Hokuto Denko HZ-5000 electrochemical
The title compound was synthesized from 1,3-bis(4- analyzer. GPC analysis for the polymer products was carried
iodophenyl)-1,3-diisopropylallene (9) and organozinc species out at 40 °C on a Shodex GPC apparatus equipped with two
derived from 4,5-bis(methylthio)TTF. Optical resolution of the SB-806M HQ GPC columns (Showa Denko K. K.) and a UV
enantiomer 3 and its precursor 9 was achieved by a recyclable detector. DMF was used as the eluent at a flow rate of
HPLC on a chiral stationary phase. The ECD spectra were 0.5 mL/min. Polystyrene standards with a narrow distribution of
measured, and the obtained spectra allowed for the validation of molecular weight (Mw: 580–377, 400) were used for molecular
the absolute configurations based on the TD-DFT method. weight calibration.
977

Beilstein J. Org. Chem. 2015, 11, 972–979.
Synthesis of 8: To a solid mixture of dried CuI (5.7 g, at rt, and then poured into saturated aqueous NH4Cl solution.
3
0 mmol) and LiBr (2.6 g, 30 mmol) was added dropwise acetyl The product was extracted by Et2O, and the organic phase was
ester 7 (6.7 g, 15 mmol) in THF (170 mL) during 15 min at rt, washed with saturated brine and dried over MgSO4. The crude
and the mixture was cooled to −78 °C. Then, freshly prepared product was purified by column chromatography on silica gel
iPrMgCl (30 mmol) in THF (15 mL) was added dropwise into with CH2Cl2/hexane (v/v = 1:4). Recrystallization from
the mixture at −78 °C. After stirring for 1 h at −78 °C, the mix- CH2Cl2/MeOH (v/v = 1:1) solution gave 3 (664 mg, 89%):
ture was further stirred for 14 h at rt. The resultant mixture was orange powder; mp: 77.8–79.2 °C; MS (APCI) m/z = 865 (M+ +
poured into saturated aqueous NH4Cl solution, and the prod- H); 1H NMR (400 MHz, CDCl3) δ 7.40 (d, J = 8.6 Hz, 4H),
ucts were extracted by Et2O. The organic phase was washed 7.34 (d, J = 8.6 Hz, 4H), 6.48 (s, 2H), 2.97 (sept, J = 6.8 Hz,
with brine and dried over MgSO4. After evaporation, the crude 2H), 2.44 (s, 6H), 2.43 (s, 6H), 1.19 (t, J = 6.8 Hz, 12H);
products were purified on silica gel column chromatography 13C NMR (100 MHz, CDCl3) δ 204.2, 136.9, 136.0, 130.8,
with the elution of hexane. Removal of the solvent afforded 8 as 127.8, 127.7, 126.7, 126.6, 117.4, 114.8, 112.8, 107.3, 28.7,
colourless oil (5.8 g, 90%): MS (GC) m/z = 432 (50%, M+: 22.8, 22.5, 19.4; IR (KBr): 2958, 2918, 2866, 1914, 1568, 1499,
C21H2279Br2), 434 (100%, M+: C21H2279Br81Br), and 436 1418, 835, 759 cm−1; anal. calcd for C37H36S12: C, 51.35; H,
(
(
50%, M+: C21H2281Br2); 1H NMR (400 MHz, CDCl3) δ 7.42 4.19; found: C, 51.36; H, 4.25.
d, J = 8.6 Hz, 2H), 7.27 (d, J = 8.6 Hz, 2H), 2.91 (septet,
J = 6.8 Hz), 1.17 (d, J = 6.8 Hz, 3H), 1.15 (d, J = 6.8 Hz, 3H); Synthesis of (R)/(S)-PTDPA: A mixture of Pd(OAc)2 (8.9 mg,
3C NMR (100 MHz, CDCl3) δ 203.0, 135.6, 131.7, 128.0, 40 μmol), P(t-Bu)3·HBF4 (35 mg, 120 mmol), Cs2CO3 (290
1
1
1
20.7, 117.1, 28.8, 22.7, 22.4; IR (neat): 2961, 2926, 2870, mg, 2.8 mmol) in degassed NMP (1 mL) was stirred for 20 min
919, 1489, 1464, 1074, 1009, 825 cm−1; HRMS (APCI-orbi- at 100 °C under Ar atmosphere. Then, (R)-3 (80 mg, 151 μmol)
trap) calcd for C21H22Br2 (M+) 432.0088; found, 432.0089.
and 4,5-bis(methylthio)TTF (67 mg, 226 μmol) were added to
the solution, and the reaction mixture was stirred for 3 days at
Synthesis of 9: To a solution of 1,3-bis(4-bromophenyl)allene 100 °C. After cooling to rt, the solvent was removed under
derivative 8 (1.0 g, 2.3 mmol) in Et2O (50 mL) was added drop- reduced pressure, and then the residue and N,N-diethylphenyl-
wise t-C4H9Li (6.0 mL, 9.8 mmol) at −78 °C under Ar atmos- azothioformamide (100 mg, 40 μmol), as a metal scavenger,
phere. After stirring for 30 min at the same temperature, C6F13I were dispersed in THF (2 mL). The resultant suspension was
(
1.3 mL, 5.84 mmol) was added dropwise by syringe. The resul- stirred for 30 min at rt, then further for 1 h at 100 °C. After
tant mixture was stirred for 3 h at −78 °C, and then saturated cooling at rt, the solution was poured into CH3OH (150 mL).
aqueous NH4Cl solution was poured into the solution at −78 °C. The resulted precipitates were collected by filtration, washing
After allowing to warming up to rt, the mixture was extracted with CH3OH. The residue on the filter was collected, and then
by Et2O. The organic phase was washed with brine and dried purified by column chromatography on non-polar polystyrene
over Na2SO4. After removal of the solvent, the crude product gel (Bio-beads S-X3 Support) with the elution of toluene. The
was purified by column chromatography on silica gel with crude product was further purified reprecipitation with toluene-
hexane elution to give colourless oil of 9 (1.0 g, 92%): MS hexane, yielding copolymer of (R)-PTDPA as an orange-brown
(
APCI) m/z = 528 (M+); 1H NMR (400 MHz, CDCl3) δ 7.62 (d, powder (24 mg, 26%). The number-average molecular weight
J = 8.6 Hz, 2H), 7.14 (d, J = 8.6 Hz, 2H), 2.94 (septet, (Mn) was estimated to be 5.6 × 103, and its distribution
J = 6.7 Hz, 1H), 1.17 (d, J = 6.8 Hz, 2H), 1.15 (d, J = 6.8 Hz, (Mn/Mw) was estimated to be 1.01: orange-brown powder;
2
1
1
H); 13C NMR (100 MHz, CDCl3) δ 202.9, 137.6, 136.0, 128.1, 1H NMR (400 MHz, CDCl3) δ 7.13–7.36, 6.46, 2.89, 2.40,
17.0, 92.2, 28.6, 22.7, 22.4; IR (neat): 2961, 2926, 2869, 1918, 1.14. In similar manner, (S)-PTDPA was obtained from the
483, 1463, 1383, 1216 cm−1; HRMS (APCI-orbitrap) calcd for reaction of (S)-3 in 31% yield. Its Mn value was estimated to be
C21H22I2 (M+) 527.98108; found, 527.98108.
2.8 × 103 and its distribution was estimated to be 1.54.
Synthesis of 3: To a solution of 4,5-bis(methylthio)TTF
Supporting Information
(
640 mg, 2.2 mmol) [20] in THF (30 mL) was added dropwise
nC4H9Li (1.3 mL, 2.2 mmol) at –78 °C under Ar atmosphere.
Supporting Information File 1
After the mixture was stirred for 90 min, a suspension of ZnCl2
Experimental procedures, characterization data, copies of
(
377 mg, 2.8 mmol) in THF (3 mL) was added at −65 °C. The
1
H and 13C NMR charts, recyclable chiral HPLC chart and
DFT calculation summary.
http://www.beilstein-journals.org/bjoc/content/
supplementary/1860-5397-11-109-S1.pdf]
solution was further stirred for 30 min, then 1,3-bis(4-iodo-
phenyl)allene derivative 9 (458 mg, 0.87 mmol) in THF
[
(
2.5 mL) and Pd(PPh3)4 (100 mg, 0.087 mmol) were added into
the mixture at –20 °C. The resultant mixture was stirred for 14 h
978

Beilstein J. Org. Chem. 2015, 11, 972–979.
1
9.Hasegawa, M.; Daigoku, K.; Hashimoto, K.; Nishikawa, H.; Iyoda, M.
Bull. Chem. Soc. Jpn. 2012, 85, 51–60. doi:10.1246/bcsj.20110224
0.Berova, N.; Nakanishi, K. Exciton Chirality Method: Principles and
Applications. In Circular dichroism: Principles and Applications;
Nakanishi, K.; Berova, N.; Eoody, R. W., Eds.; Wiley: Hoboken, NJ,
U.S.A., 1994; pp 361–398.
Acknowledgements
The authors gratefully acknowledge partial financial aid from
Kitasato University Research Grant for young researchers. We
also thank to Prof. Dr. Takahiro Tsuchiya for helpful discus-
sion. The calculations were performed at the Research Centre
for Computational Science, Okazaki, Japan.
2
21.Gaussian 09, Revision D.01; Gaussian, Inc.: Wallingford, CT, U.S.A.,
010.
2.Mitamura, Y.; Yorimitsu, H.; Oshima, K.; Osuka, A. Chem. Sci. 2011, 2,
017–2021. doi:10.1039/c1sc00372k
2
2
References
2
1.
Mammana, A.; Carroll, G. T.; Feringa, B. L. Circular dichroism of
dynamic systems: switching molecular chirality and supramolecular
chirality. In Comprehensive Chiroptical Spectroscopy; Berova, N.;
Polavarapu, P. L.; Nakanishi, K.; Eoody, R. S., Eds.; Wiley: Hoboken,
NJ, U.S.A., 2012; Vol. 2, pp 289–316.
License and Terms
2
3
4
.
.
.
Feringa, B. L.; van Delden, R. A.; Koumura, N.; Geertsema, E. M.
Chem. Rev. 2000, 100, 1789–1816. doi:10.1021/cr9900228
Canary, J. W. Chem. Soc. Rev. 2009, 38, 747–756.
This is an Open Access article under the terms of the
Creative Commons Attribution License
(http://creativecommons.org/licenses/by/2.0), which
doi:10.1039/b800412a
permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.
Nishida, J.-i.; Suzuki, T.; Ohkita, M.; Tsuji, T. Angew. Chem., Int. Ed.
2
001, 40, 3251–3254.
doi:10.1002/1521-3773(20010903)40:17<3251::AID-ANIE3251>3.0.CO
2-P
;
The license is subject to the Beilstein Journal of Organic
Chemistry terms and conditions:
5
.
.
Deng, J.; Song, N.; Zhou, Q.; Su, Z. Org. Lett. 2007, 9, 5393–5396.
doi:10.1021/ol701822u
(http://www.beilstein-journals.org/bjoc)
6
Pospíšil, L.; Bednárová, L.; Štěpánek, P.; Slavíček, P.; Vávra, J.;
Hromadová, M.; Dlouhá, H.; Tarábek, J.; Teplý, F. J. Am. Chem. Soc.
2
014, 136, 10826–10829. doi:10.1021/ja500220j
The definitive version of this article is the electronic one
which can be found at:
7.
Kobayakawa, K.; Hasegawa, M.; Sasaki, H.; Endo, J.; Matsuzawa, H.;
Sako, K.; Yoshida, J.; Mazaki, Y. Chem. – Asian J. 2014, 9,
doi:10.3762/bjoc.11.109
2
751–2754. doi:10.1002/asia.201402667
Diederich, F.; Rivera-Fuentes, P. Angew. Chem., Int. Ed. 2012, 51,
818–2828. doi:10.1002/anie.201108001
8
9
1
1
1
1
.
2
.
Krause, N.; Hashimi, A. S. K., Eds. Modern Allene Chemistry;
Wiley-VCH: Weinheim, Germany, 2004.
0.Hasegawa, M.; Sone, Y.; Iwata, S.; Matsuzawa, H.; Mazaki, Y.
Org. Lett. 2011, 13, 4688–4691. doi:10.1021/ol201857f
1.Roth, W. R.; Ruf, G.; Ford, P. W. Chem. Ber. 1974, 107, 48–52.
doi:10.1002/cber.19741070106
2.Alonso-Gómez, J. L.; Rivera-Fuentes, P.; Seiler, P.; Diederich, F.
Chem. – Eur. J. 2008, 14, 10564–10568. doi:10.1002/chem.200801456
3.Odermatt, S.; Alonso-Gómez, L.; Seiler, P.; Cid, M. M.; Diederich, F.
Angew. Chem., Int. Ed. 2005, 44, 5074–5078.
doi:10.1002/anie.200501621
1
4.Hasegawa, M.; Iwata, S.; Sone, Y.; Endo, J.; Matsuzawa, H.;
Mazaki, Y. Molecules 2014, 19, 2829–2841.
doi:10.3390/molecules19032829
15.Thorand, S.; Vögtle, F.; Krause, N. Angew. Chem., Int. Ed. 1999, 38,
3
721–3723.
doi:10.1002/(SICI)1521-3773(19991216)38:24<3721::AID-ANIE3721>3
0.CO;2-9
.
1
6.Clay, M. D.; Fallis, A. G. Angew. Chem., Int. Ed. 2005, 44, 4039–4042.
doi:10.1002/anie.200500484
17.Kijima, M.; Hiroki, K.; Shirakawa, H. Macromol. Rapid Commun. 2002,
2
3, 901–904.
doi:10.1002/1521-3927(20021001)23:15<901::AID-MARC901>3.0.CO;
-3
8.Pu, X.; Qi, X.; Ready, J. M. J. Am. Chem. Soc. 2009, 131,
0364–10365. doi:10.1021/ja9041127
2
1
1
979