Preparation of phthalocyanines with eight benzylchalcogeno substituents from 5,6-dibromo-4,7-diethylbenzo[1,2,3]trichalcogenoles

Article abstract of DOI:10.1021/jo030354j

Benzo[1,2,3]trichalcogenoles with two bromine atoms on the benzene ring, 5,6-dibromo-4,7-diethylbenzo[1,2,3]trichalcogenoles (1a) and (1b) (chalcogen: 1a = S; 1b = Se), were first prepared by treating 2,3,5,6-tetrabromo-1,4- diethylbenzene (TBDEB) with el

Full text of DOI:10.1021/jo030354j

P r ep a r a tion of P h th a locya n in es w ith Eigh t Ben zylch a lcogen o
Su bstitu en ts fr om
5,6-Dibr om o-4,7-d ieth ylben zo[1,2,3]tr ich a lcogen oles
Takeshi Kimura,* Akinori Yomogita, Tomoya Matsutani, Takahiro Suzuki, Ichiro Tanaka,
Yasushi Kawai,† Yutaka Takaguchi,‡ Takatsugu Wakahara,§ and Takeshi Akasaka§
Center for Instrumental Analysis, Iwate University, Morioka, Iwate 020-8551, J apan, Institute for
Chemical Research, Kyoto University, Uji, Kyoto 611-0011, J apan, Department of Environmental
Chemistry and Materials, Okayama University, Okayama, Okayama 700-8530, J apan, and Center for
Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Ibaraki 305-8577, J apan
kimura@iwate-u.ac.jp
Received November 17, 2003
Benzo[1,2,3]trichalcogenoles with two bromine atoms on the benzene ring, 5,6-dibromo-4,7-
diethylbenzo[1,2,3]trichalcogenoles (1a ) and (1b) (chalcogen: 1a ) S; 1b ) Se), were first prepared
by treating 2,3,5,6-tetrabromo-1,4-diethylbenzene (TBDEB) with elemental sulfur or amorphous
selenium in DBU at 140 °C (for 1a ) and 100 °C (for 1b) for 24 h. The structures of 1a and 1b were
verified by NMR spectroscopy, mass spectrometry, and elemental analysis. X-ray crystallographic
analysis ultimately showed that the substitution reactions of TBDEB proceeded at the two adjacent
bromine atoms. To apply 1a and 1b to construction of phthalocyanine derivatives with sulfur or
selenium functional groups, 4,5-bis(benzylchalcogeno)-3,6-diethylphthalonitriles (5a ) and (5b) as
key intermediates were prepared by way of introduction of alkyl groups (2-cyanoethyl or
4-nitrophenethyl groups) on two chalcogen atoms, substitution of two bromine atoms with nitrile
groups, and subsequent exchange of alkyl groups with benzyl groups. Compound 5a was treated
with lithium in n-pentanol at 100 °C for 1 h to produce 2,3,9,10,16,17,23,24-octakis(benzylthio)-
1,4,8,11,15,18,22,25-octaethylphthalocyanine (6a ). A similar treatment of 5b in n-hexanol at 100
1
°C for 2 h gave phthalocyanine 6b. The structures of 6a and 6b were determined by H NMR
spectroscopy and MALDI-TOFMS. X-ray crystallographic analysis of 6a was also performed. The
Q-band absorptions (λmax) for 6a and 6b in UV-vis spectra were observed at 755 nm (log ꢀ ) 5.1)
and 757 nm (log ꢀ ) 5.1), respectively, and their electrochemical properties were verified by cyclic
voltammetry in dichloromethane with Ag/AgNO3 as a reference electrode. Compounds 6a and 6b
were further treated with lithium in THF/NH3 at -78 °C and then with dibutyltin dichloride to
produce phthalocyanine derivatives 8a and 8b with four dichalcogenastannole rings by way of
octachalcogenate phthalocyanines 7a and 7b.
In tr od u ction
in the near-infrared region. An unadorned phthalocya-
nine and its metalated derivatives usually exhibit Q-band
absorption at around 680 nm. Since a redshift of the
Q-band wavelength is a critical element in the application
of phthalocyanines to advanced materials, there have
been many investigations regarding the design and
preparation of functionalized phthalocyanines and their
Phthalocyanines are important materials and continue
to attract considerable attention because the molecules
have a variety of potential applications including use as
photosensitizers, catalysts, optical disks, charge-generat-
ing materials, and photodynamic therapy.1-8 Unlike
porphyrin derivatives, phthalocyanines have the promi-
nent property of exhibiting intense absorption (Q-band)
(4) (a) Kobayashi, N.; Ishizaki, T.; Ishii, K.; Konami, H. J . Am. Chem.
Soc. 1999, 121, 9096-9110. (b) Kobayashi, N.; Higashi, R.; Ishii, K.;
Hatsusaka, K.; Ohta, K. Bull. Chem. Soc. J pn. 1999, 72, 1263-1271.
(c) Kobayashi, N.; Fukuda, T.; Ueno, K.; Ogino, H. J . Am. Chem. Soc.
2001, 123, 10740-10741. (d) Kobayashi, N.; Miwa, H.; Nemykin, V.
N. J . Am. Chem. Soc. 2002, 124, 8007-8020. (e) Kobayashi, N.;
Fukuda, T. J . Am. Chem. Soc. 2002, 124, 8021-8034. (f) Fukuda, T.;
Stork, J . R.; Potucek, R. J .; Olmstead, M. M.; Noll, B. C.; Kobayashi,
N.; Durfee, W. S. Angew. Chem., Int. Ed. 2002, 41, 2561.
(5) (a) Vagin, S. I.; Hanack, M. Eur. J . Org. Chem. 2002, 2859-
2865. (b) Calvete, M.; Hanack, M. Eur. J . Org. Chem. 2003, 2080-
2983.
† Kyoto University.
‡ Okayama University.
§ University of Tsukuba.
(1) (a) Kobayashi, N. Coord. Chem. Rev. 2002, 227, 129-152. (b)
Kobayashi, N. Bull. Chem. Soc. J pn. 2002, 75, 1-19. (c) Phthalo-
cyaninessChemistry and Functions; Shirai, H., Kobayashi, N., Eds.;
IPC: Tokyo, 1997 (in J apanese).
(2) (a) Maya, E. M.; Garc´ıa, C.; Garc´ıa-Frutos, E. M.; Va´zquez, P.;
Torres, T. J . Org. Chem. 2000, 65, 2733-2739. (b) Nicolau, M.;
Cabezo´n, B.; Torres, T. J . Org. Chem. 2001, 667, 89-93.
(3) (a) Kobayashi, N.; Lam, H.; Nevin, W. A.; J anda, P.; Leznoff, C.
C.; Koyama, T.; Monden, A.; Shirai, H. J . Am. Chem. Soc. 1994, 116,
879-890. (b) Terekhov, D. S.; Nolan, K. J . M.; McArthur, C. R.; Leznoff,
C. C. J . Org. Chem. 1996, 61, 3034-3040.
(6) (a) Cook, M. J .; Heeney, M. J . Chem. Commun. 2000, 969-970.
(b) Cook, M. J .; Heeney, M. Chem. Eur. J . 2000, 6, 3958-3967. (c)
Garc´ıa-Frutos, E. M.; Ferna´ndez-La´zaro, F.; Maya, E. M.; Va´zquez,
P.; Torres, T. J . Org. Chem. 2000, 65, 6841-6846.
10.1021/jo030354j CCC: $27.50 © 2004 American Chemical Society
Published on Web 06/12/2004
4716
J . Org. Chem. 2004, 69, 4716-4723

Preparation of Phthalocyanines
SCHEME 1
related molecules. For instance, a variety of character-
istics have been added to the molecules (1) by introducing
several heteroatoms to the periphery of the molecules,8
(2) by distorting the molecular plane with steric con-
gestion,4c,e,f and (3) by expanding the π-conjugation
system (i) with the fusion of several aromatic rings,4d,5a,7c
(ii) with the conjunction of phthalocyanines with alkynyl
groups,6,7a and (iii) with the construction of binuclear
phthalocyanines.3a,5b
Conversely, we have reported on the preparation,
structure, reactivity, and electrochemical properties of
several benzoannelated oligosulfides, benzo[1,2,3,4,5]-
pentathiepins, and benzo[1,2,3]trithioles.9-12 In these
reports, the preparation of 4,8-diethylbenzo[1,2-d:4,5-d′]-
bis[1,2,3]trithiole (DEBBT) represents one of the most
vital results. DEBBT was prepared in good yield in a
one-step reaction by treating 2,3,5,6-tetrabromo-1,4-
diethylbenzene (TBDEB) with elemental sulfur in liquid
ammonia at 120 °C (eq 1).9 From our continuing study
1a and 1b to synthesize phthalocyanines with several
sulfur or selenium functional groups. In this paper, we
report on (1) the preparation of 4,5-bis(benzylchalcogeno)-
3,6-diethylphthalonitriles 5a and 5b from 1a and 1b by
three-step reactions; (2) their application to the syn-
thesis of new phthalocyanines, 2,3,9,10,16,17,23,24-
octakis(benzylchalcogeno)-1,4,8,11,15,18,22,25-octaalkyl-
phthalocyanines with eight peripheral sulfur or selenium
atoms; and (3) debenzylation of 6a and 6b and stan-
nylation of octachalcogenate phthalocyanines 7a and 7b
giving phthalocyanines 8a and 8b with four dichalcoge-
nastannole rings. In addition, the results of measuring
6a and 6b by cyclic voltammetry and UV-vis spectra for
6a , 6b, 8a , and 8b are also described.
of several cyclic oligosulfides, we serendipitously found
that treatment of TBDEB with elemental sulfur in DBU
at 140 °C, produced 5,6-dibromo-4,7-diethylbenzo[1,2,3]-
trithiole (1a ), a benzo[1,2,3]trithiole derivative with two
adjacent bromine atoms, in moderate yield.13 By a similar
treatment, 5,6-dibromo-4,7-diethylbenzo[1,2,3]triselenole
(1b), a selenium derivative, was obtained in good yield.
Since these molecules have two bromine atoms, substi-
tuting the bromine atoms with two nitrile groups or with
a diiminoisoindoline structure enables the application of
Resu lts a n d Discu ssion
P r ep a r a t ion of 5,6-Dib r om o-4,7-d iet h ylb en zo-
[1,2,3]tr ich a lcogen oles (1a ) a n d (1b). As a typical
procedure for introducing sulfur atoms at adjacent posi-
tions on the benzene ring, TBDEB was treated with
elemental sulfur in DBU at 140 °C for 24 h. We initially
expected the production of DEBBT by this reaction, in
a manner similar to the reaction of TBDE B with
elemental sulfur in liquid ammonia (eq 1).9 After the
usual workup and purification by column chromatogra-
phy and recrystallization, to our surprise, 1a was ob-
tained as orange crystals in 59% yield (Scheme 1), while
no DEBBT was obtained at all. The result is different
from the reaction shown in eq 1, and the reaction seems
to depend on the solvent. The selenium derivative 1b was
also obtained in 54% yield by the reaction of TBDEB
with amorphous selenium in DBU at 100 °C for 24 h.
This is the first instance of the direct preparation of a
benzo[1,2,3]triselenole derivative by a one-step reaction
of 1,2-dibromobenzene with selenium reagents. The
structures of 1a and 1b were verified by NMR spectros-
copy, mass spectrometry, and elemental analysis. Since
recrystallization of 1a and 1b gave orange and dark red
crystals, respectively, which are suitable for crystal-
lography, their structures were finally determined by
X-ray crystallographic analysis. The crystal data, bond
length, and bond angles of 1a are shown in the Support-
ing Information. As shown in Figure 1, 1a apparently
has one trithiole ring and two bromine atoms on the
benzene ring, clearly suggesting that the substitution
reaction of TBDEB with the sulfur atoms proceeds at
the two adjacent bromine atoms. The structure of the
(7) (a) Miller, M. A.; Lammi, R. K.; Prathapan, S.; Holten, D.;
Lindsey, J . S. J . Org. Chem. 2000, 65, 6634-6649. (b) Li, J .; Gryko,
D.; Dabke, R. B.; Diers, J . R.; Bocian, D. F.; Kuhr, W. G.; Lindsey, J .
S. J . Org. Chem. 2000, 65, 7379-7390. (c) Mitzel, F.; FitzGerald, S.;
Beeby, A.; Faust, R. Chem. Eur. J . 2003, 9, 1233-1241.
(8) (a) Stuzhin, P. A.; Bauer, E. M., Ercolani, C. Inorg. Chem. 1998,
38, 1533-1539. (b) Pullen, A. E.; Faulmann, C.; Cassoux, P. Eur. J .
Inorg. Chem. 1999, 269-276. (c) Bauer, E. M.; Ercolani, C.; Galli, P.;
Popkova, I. A.; Stuzhin, P. A. J . Porphyrins Phthalocyanines 1999, 3,
371-379. (d) Baum, S. M.; Trabanco, A. A.; Montalban, A. G.; Micallef,
A. S.; Zhong, C.; Meunier, H. G.; Suhling, K.; Phillips, D.; White, A. J .
P.; Williams, D. J .; Barrett, A. G. M.; Hoffman, B. M. J . Org. Chem.
2003, 68, 1665-1670.
(9) Sato, R.; Kimura, T.; Goto, T.; Saito, M.; Kabuto, C. Tetrahedron
Lett. 1989, 30, 3453-3456.
(10) (a) Kimura,T.; Hanzawa, M.; Horn, E.; Kawai, Y.; Ogawa, S.;
Sato, R. Tetrahedron Lett. 1997, 38, 1607-1610. (b) Kimura, T.; Kawai,
Y.; Ogawa, S.; Sato, R. Chem. Lett. 1999, 1305-1306. (c) Kimura, T.;
Hanzawa, M.; Tsujimura, K.; Takahashi, T.; Kawai, Y.; Horn, E.; Fujii,
T.; Ogawa, S.; Sato, R. Bull. Chem. Soc. J pn. 2002, 75, 817-824. (d)
Kimura, T.; Hanzawa, M.; Ogawa, S.; Sato, R.; Fujii, T.; Kawai, Y.
Heteroatom Chem. 2003, 14, 88-94.
(11) (a) Kimura, T.; Tsujimura, K.; Mizusawa, S.; Ito, S.; Kawai,
Y.; Ogawa, S.; Sato, R. Tetrahedron Lett. 2000, 41, 1801-1805. (b)
Kimura, T.; Mizusawa, S.; Yoneshima, A.; Ito, S.; Tsujimura, K.;
Yamashita, T.; Kawai, Y.; Ogawa, S.; Sato, R. Bull. Chem. Soc. J pn.
2002, 75, 2647-2653.
(12) (a) Kimura,T.; Ito, S.; Sasaki, T.; Niizuma, S.; Ogawa, S.; Sato,
R.; Kawai, Y. Chem. Lett. 2002, 540-541. (b) Kimura, T.; Sasaki, T.;
Yamaki, H.; Suzuki, E.; Niizuma, S. Eur. J . Org. Chem. 2003, 4902-
4908.
(13) Activation of elemental sulfur and amorphous selenium with
DBU was previously reported: (a) Tokitoh, N.; Hayakawa, H.; Goto,
M.; Ando, W. Tetrahedron Lett. 1988, 29, 1935-1938. (b) Ishii, A.;
Furusawa, K.; Omata, T.; Nakayama, J . Heteroatom Chem. 2002, 13,
351-356.
J . Org. Chem, Vol. 69, No. 14, 2004 4717

Kimura et al.
SCHEME 2
F IGURE 1. ORTEP drawing of 1a .
benzotrithiole moiety is similar to that of DEBBT. The
crystal data, ORTEP drawing, bond length, and bond
angles of 1b are also shown in Supporting Information.
In contrast to 1a , compound 1b is shown to have one
triselenole ring and two bromine atoms on the benzene
ring. In the 77Se NMR spectrum of 1b, two signals were
observed at δ ) 457.5 and 576.8 ppm, and the Se-Se
spin coupling constant of the two selenium atoms is
J Se-Se)260 Hz. To our knowledge, the benzo[1,2,3]-
trithiole and benzo[1,2,3]triselenole derivatives with two
bromine atoms on the benzene ring were obtained for the
first time by these procedures.
In contrast, 1-(2-cyanoethylthio)-2,5-diethyl-3,4,6-tri-
bromobenzene gave 1a in 38% yield by treatment with
elemental sulfur in DBU at 130 °C for 24 h.14 The
reaction is expected to proceed via 2,5-diethyl-3,4,6-
tribromobenzenethiolate as an intermediate. On the basis
of this reaction, we predicted a reaction mechanism of
TBDEB with sulfur or selenium in DBU as follows. (1)
The production of 1a and 1b is initiated by the aromatic
nucleophilic substitution reaction of one bromine atom
of TBDEB with activated sulfur or selenium atoms. (2)
Subsequent intramolecular substitution and cyclization
reactions give benzochalcogeniiren as an intermediate.15
(3) Benzochalcogeniiren is further chalcogenized to pro-
duce 1a and 1b. However, the details of the mechanism
of this substitution reaction are not clear.
phthalonitriles, as the key intermediates, was examined
using following procedure. Compound 1a was initially
treated with copper(I) cyanide in DMF at 120 °C under
an argon atmosphere.16 Because of the instability of the
trithiole ring under the reaction conditions, a complex
mixture was obtained together with a trace amount of
5,6-dicyano-4,7-diethylbenzo[1,2,3]trithiole (2a ).17
Because the trithiole ring was unstable under the
reaction conditions and we were unable to improve the
yield of 2a , we tried to introduce two 2-cyanoethyl groups
onto the sulfur atoms as a protecting group for the thiols
(Scheme 2).18 Compound 1a was first treated with sodium
borohydride and potassium carbonate and then 2-cyano-
ethyl bromide in THF/methanol at room temperature.
After the usual workup and purification by column
chromatography, 1,2-bis(2-cyanoethylthio)-3,6-diethyl-
4,5-dibromobenzene (3a ) was obtained in 48% yield. The
substitution of the bromine atoms with the nitrile groups
was then examined by a method similar to the one
described above. The reaction of 3a with copper(I) cyanide
in DMF at 130 °C for 6 h under an argon atmosphere
gave 4,5-bis(2-cyanoethylthio)-3,6-diethylphthalonitrile
(4a ) in 53% yield.
P r ep a r a tion of P h th a locya n in es w ith Eigh t Ben -
zylth io Gr ou p s. If it is possible to substitute the
bromine atoms with the nitrile groups and get the
corresponding phthalonitriles, 1a and 1b could be applied
to the preparation of phthalocyanines with sulfur or
selenium functional groups. To construct phthalocyanines
with eight peripherally substituted chalcogeno substit-
uents, transformation of 1a and 1b to the corresponding
There are many procedures for preparing phthalocya-
nines. As preliminary experiments, according to the
method for preparing phthalocyanines under the mild
conditions reported by Kobayashi et al., 2a and 4a were
(16) (a) Ellis, G. P.; Romney-Alexander, T. M. Chem. Rev. 1987, 87,
779-794. (b) Rehahn, M.; Schlu¨ter, A.-D.; Feast, W. J . Synthesis 1988,
386-388.
(14) 1-(2-Cyanoethylthio)-2,5-diethyl-3,4,6-tribromobenzene was ob-
tained as a minor product together with 3a when the crude product of
1a was treated with sodium borohydride, potassium carbonate, and
then 2-cyanoethyl bromide in THF/methanol.
(15) (a) Cadogan, J . I. G.; Sharp, J . T.; Trattles, M. J . J . Chem. Soc.,
Chem. Commun. 1974, 900-901. (b) Wooldridge, T.; Roberts, T. D.
Tetrahedron Lett. 1977, 2643-2646. (c) White, R. C.; Scoby, J .; Roberts,
T. D. Tetrahedron Lett. 1979, 2785-2788. (d) Nakayama, J . Sulfur
Lett. 1989, 9, 83-86. (e) Campbell, C. D.; Rees, C. W. J . Chem. Soc. C
1969, 752-756; Nakayama, J .; Kashiwagi, M.; Yomoda, R.; Hoshino,
M. Nipponkagakukaishi 1987, 1424-1429 (in J apanese).
(17) Compound 2a is the first instance of benzo[1,2,3]trithiole
derivatives with two nitrile groups. The structure of 2a was determined
by NMR spectroscopy, IR spectroscopy, mass spectrometry, elemental
analysis, and finally by X-ray crystallographic analysis (see the
Experimental section and the Supporting Information). The structure
of 2a clearly has one trithiole ring and two nitrile groups on the
benzene ring. The oxidation potentials of 2a are listed in Table 2.
(18) Simonsen, K. B.; Svenstrup, N.; Lau, J .; Thorup, N.; Becher, J .
Angew. Chem., Int. Ed. 1999, 38, 1417-1419. Spanggaard, H.; Prehn,
J .; Nielsen, M. B.; Levillain, E.; Allain, M.; Becher, J . J . Am. Chem.
Soc. 2000, 122, 9486-9494.
4718 J . Org. Chem., Vol. 69, No. 14, 2004

Preparation of Phthalocyanines
then treated by sodium methoxide in THF solution.19
These reactions, however, gave complex mixtures and no
phthalocyanines with the trithiole ring or 2-cyanoeth-
ylthio groups. We then chose the benzyl group as a
protecting group for the thiols instead of the 2-cyano-
ethylthio groups, and 4,5-bis(benzylthio)-3,6-diethyl-
phthalonitrile (5a ) was prepared in 45% yield by treating
4a with cesium hydroxide and then benzyl bromide in
THF/methanol at room temperature.
SCHEME 3
In contrast, to prepare 5a , 1,2-bis(benzylthio)-3,6-
diethyl-4,5-dibromobenzene was prepared from 1a by
treatment with sodium borohydride, potassium carbon-
ate, and then benzyl bromide in THF/methanol and was
subsequently reacted with copper(I) cyanide in DMF. In
this reaction, however, elimination of the benzyl group
seemed to proceed readily together under the reaction
conditions with the substitution of the bromine atoms
with the nitrile groups. The reaction resulted in complex
products. Although 5a was obtained in 10% yield after
repeated column chromatography, the purification of 5a
prepared by this procedure was more difficult than that
of 5a obtained by the alkyl exchange reaction of 4a .
We then tried to construct the target molecule by the
method reported by Kobayashi et al., which is known as
a good procedure for synthesizing sterically congested
phthalocyanines.4c Compound 5a was reacted with lithium
in n-pentanol at 140 °C under an argon atmosphere. The
solution immediately changed color to dark green. After
being stirred for 1 h, the reaction mixture was cooled to
room temperature and poured into methanol containing
hydrochloric acid. A blue-green solid precipitated out of
the solution. The precipitate was filtered, washed with
methanol, and dried under vacuum. Through this treat-
ment, a trace amount of 6a was obtained as dark green
crystals after purification by column chromatography. It
seemed that the higher temperature and longer reaction
time produced a lower yield. After several examinations
of the reaction conditions, 5a was treated with lithium
in n-pentanol at 100 °C for 1 h under an argon atmo-
sphere, giving the best result; 6a was obtained in 39%
yield (Scheme 3). Compound 6a is a soluble molecule in
several organic solvents (dichloromethane, chloroform,
and THF), although it is insoluble in acetonitrile and
methanol. The structure of 6a was determined by 1H
NMR spectroscopy, UV-vis spectroscopy, and MALDI-
TOFMS. As a conspicuous property of the 1H NMR
spectra measured in chloroform-d, the chemical shift for
methylene protons of the two ethyl groups shows a large
downfield shift (δ ) 4.60 ppm), suggesting that the two
neighboring ethyl groups are in close proximity and that
the methylene protons are affected by the steric conges-
tion between them. The protons on the nitrogen atoms
of the pyrrole rings could not be observed in the spectra.
To determine the optical properties of 6a , the absorption
wavelength (λmax) and molar-extinction coefficient (ꢀ) were
determined by UV-vis spectroscopy. The λmax value of
6a was observed at 755 nm (log ꢀ ) 5.1) in the spectrum,
showing a large redshift of the λmax value compared to
that of unsubstituted phthalocyanines.
precedent reports with respect to phthalocyanine deriva-
tives with selenium substituents, although porphyrazine
derivatives with the selenadiazole ring were reported by
Ercolani et al. and Barrett et al.8 We then attempted to
prepare phthalocyanines with selenium functional groups.
In the process, the 4-nitrophenethyl group was used as
an alkyl group instead of the 2-cyanoethyl group used in
preparing the sulfur derivative. We did this because it
is well-known that the bond energy of the Se-C bond is
lower than that of the S-C bond, and the S-C bond of
the 4-nitrophenethylthio group is known to be able to
better bear the reaction conditions than that of the
2-cyanoethylthio group.18 Therefore, 1,2-bis(4-nitrophen-
ethylseleno)-3,6-diethyl-4,5-dibromobenzene (3b) was pre-
pared by treating 1b with sodium borohydride and
potassium carbonate. Then, 4-nitrophenethylbromide was
added to THF/methanol at 60 °C under an argon atmo-
sphere. With this procedure, 3b was produced in 61%
yield. Preparation of phthalonitrile was subsequently
attempted by reacting 3b with copper(I) cyanide in DMF
at 100 °C for 6 h under an argon atmosphere. After
purification by column chromatography, 4,5-bis(4-nitro-
phenethylseleno)-3,6-diethylphthalonitrile (4b) was ob-
tained in 37% yield. The higher reaction temperature
gave a lower yield of 4b. Since we can obtain 4b, we
attempted to prepare phthalocyanine with the 4-nitro-
phenethylseleno groups by the reaction of 4b with lithium
in n-pentanol at 100 °C under an argon atmosphere.
However, we were unable to obtain the product.
Consequently, we tried to exchange the 4-nitrophen-
ethylseleno groups with the benzylseleno groups. Thus,
4b was treated with sodium methoxide in methanol/THF
and then benzyl bromide at room temperature. This
treatment produced 4,5-bis(benzylseleno)-3,6-diethylphth-
alonitrile (5b) in 57% yield.20 When 5b was treated with
lithium in n-hexanol at 100 °C under an argon atmo-
sphere, the solution immediately changed color to dark
green. After being stirred for 2 h, the reaction mixture
was treated by a procedure similar to that described
above, and a dark green product 6b was obtained in 25%
P r ep a r a tion of P h th a locya n in es w ith Eigh t Ben -
zylselen o Gr ou p s. To our knowledge, there are no
1
yield. The structure of 6b was determined by H NMR
spectroscopy, UV-vis spectroscopy, and MALDI-TOFMS.
(19) Nemykin, V. N.; Kobayashi, N.; Mytsyk, V. M.; Volkov, S. V.
Chem. Lett. 2000, 546-547.
1
The solubility and H NMR spectrum of 6b are similar
J . Org. Chem, Vol. 69, No. 14, 2004 4719

Kimura et al.
TABLE 1. Cr ysta l Da ta of 6a
6a
crystal system
space group
crystal color
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
triclinic
P1h
dark green
15.301(7)
16.10(1)
21.64(1)
77.42(4)
89.92(4)
70.89(4)
4903.3(4)
2
Z
D
calc (g/cm3)
1.357
4.00
11.44
µ (cm-1
)
refl/param ratio
R
0.046
Rw
GOF
0.065
1.12
F IGURE 2. ORTEP drawing of 6a (two CHCl3 molecules and
all hydrogen atoms are omitted).
to those of the sulfur derivative 6a . Compound 6b has
eight selenium atoms arranged peripherally and, hence,
we can characterize the molecule by the 77Se NMR
spectrum. In the spectrum, the signal of 6b was observed
at δ ) 356.0 ppm, which is a value shifted upfield from
those of 5b (δ ) 389.6 ppm) and 1,2-bis(benzylseleno)-
4,5-dibromo-3,6-diethylbenzene (δ ) 390.8 ppm). In the
UV-vis spectrum, the λmax value of 6b is 757 nm (logꢀ )
5.1), which is only 2 nm longer than that of 6a . The
HOMO-LUMO gaps of 6a and 6b, estimated from
Q-band absorption, are both 1.64 eV.
X-r ay Cr ystallogr aph y an d Electr och em ical P r op-
er ties. Recrystallization of 6a from chloroform/methanol
gave dark green rhombic crystals, and they are suitable
for single-crystal X-ray crystallography. We then per-
formed X-ray crystallographic analysis and found that
6a crystallizes in triclinic form and that the space group
is P1h (#2). The unit cell consists of two molecules of 6a
in the crystal, and four molecules of chloroform are
further contained in the unit cell. The crystal data is
shown in Table 1. Meanwhile, the ORTEP drawing
reveals that the form of the phthalocyanine skeleton is
nearly planar. In the structure, two benzylthio groups
on the same benzene ring are directed in opposite
directions and are perpendicular to the plane of the
phthalocyanine, while the two ethyl groups in close
proximity are also oriented in alternate directions (Figure
2). It seems that the two sterically congested ethyl groups
cause a slight distortion in the phthalocyanine skeleton.
To determine the electrochemical properties, the redox
potentials of 6a and 6b were then measured by cyclic
voltammetry with silver nitrate used as the reference
electrode (Table 2). As shown in Figure 3 and Table 2,
two reversible oxidation potentials (E1/2 ) 0.49 and 0.72
V) and two reversible reduction potentials (E1/2 ) -1.02
and -1.31 V) were observed for 6a , while one reversible
oxidation potential (E1/2 ) 0.46 V), one irreversible
TABLE 2. Red ox P oten tia ls (vs Ag/AgNO3)
E1/2 (V)
second
first
first
reduction
second
reduction
compd
oxidation
oxidation
1a a
1ba
2a b
2bb
5a b
5bb
6a c
6bc
0.99
0.77
1.09
0.87
1.40e
0.95e
0.49
0.46
-1.04e
-0.68
-1.16d
-1.15d
-1.02
-1.03
0.72
-1.31
-1.32
0.74e
a
b
Measured in CH2Cl2/CH3CN ) 1:1. Measured in CH3CN.
c Measured in CH2Cl2. Quasi reversible. e Irreversible (Ep/V).
d
F IGURE 3. Cyclic voltammogram of 6a (1.1 mmol/L).
oxidation potential (Ep ) 0.74 V), and two reversible
reduction potentials (E1/2 ) -1.03 and -1.32 V) were
observed for 6b. It appears that the oxidation potentials
of 6b are slightly lower than those of 6a , while the
reduction potentials of 6b are similar to those of 6a . The
differences in potential (∆E) between the first oxidation
potential and the first reduction potential were calculated
to estimate the HOMO-LUMO gap of 6a and 6b. The
calculation reveals that the gaps of 6a and 6b are ∆E )
1.51 and 1.49 V, respectively.
(20) 5,6-Dicyano-4,7-diethylbenzo[1,2,3]triselenole (2b) was prepared
by treating 4b with CsOH‚H2O and then amorphous selenium in THF
and MeOH. The structure of 2b was determined by NMR spectroscopy,
mass spectrometry, and elemental analysis (see the Experimental
Section). In the 77Se NMR spectrum of 2b, two signals were observed
at δ 463.5 and 563.5 ppm, and the Se-Se spin coupling constant of
two selenium atoms is J Se-Se ) 271 Hz. X-ray crystallographic analysis
shows that the structure of 2b has one triselenole ring and two nitrile
groups on the benzene ring (see the Supporting Information). The
oxidation potentials of 2b are listed in Table 2.
In contrast, benzotrichalcogenoles 1a , 1b, 2a , and 2b
show reversible oxidation potentials at E1/2 ) 0.99, 0.77,
1.10, and 0.87 V, respectively, which are higher than
those of the benzotrichalcogenoles without the two bro-
4720 J . Org. Chem., Vol. 69, No. 14, 2004

Preparation of Phthalocyanines
mine atoms and two nitrile groups.21 Interestingly, while
the reduction potential of 2a is observed at Ep ) -1.02
V as an irreversible wave, 2b shows a reversible reduc-
tion potential at E1/2 ) -0.68 V, revealing that 2b acts
as both an electron donor and acceptor.
SCHEME 4
Deben zyla tion of 6a a n d 6b a n d Cycliza tion of
Lith iu m Octa ch a lcogen a te w ith Bu 2Sn Cl2. To pre-
pare phthalocyanines modified peripherally, debenzyla-
tion and functionalization reactions of 6a and 6b were
attempted by Birch reduction using lithium metal in
THF/liquid ammonia.22 First, 6b was treated with lithium
metal in THF/liquid ammonia and then elemental sele-
nium. However, no soluble product was obtained by this
reaction, suggesting that debenzylated phthalocyanine
derivatives have low solubility. We then selected dibu-
tyltin dichloride as an electrophile in a method similar
to that reported by Hoffman.23,24 The benzyl groups of
6b were removed by using lithium metal in THF/liquid
ammonia (Scheme 4). The octaselenolate 7b generated
was very air sensitive. After removal of the ammonia,
dibutyltin dichloride in THF/methanol was added to the
THF solution of 7b, and the solution was stirred for 1 h
at room temperature. Then the solvent was evaporated,
and the product was separated by silica gel column
chromatography to produce phthalocyanine with four
diselenastannole rings in 23% yield. Similar treatment
of 6a with lithium/ammonia/THF and resulting octathi-
olate 7a with dibutyltin dichloride yielded 8a in 18%
yield. The structures of 8a and 8b were determined by
1H, 77Se, and 119Sn NMR spectroscopy and MALDI-
TOFMS. In the 77Se NMR spectrum, the signal of 8b was
observed at δ ) 82.4 ppm, while 119Sn NMR signals
appeared at 177.6 for 8a and 88.2 for 8b. These chemical
shifts are similar to those of benzodichalcogenastan-
noles.21 Under UV-vis spectroscopy, the λmax value of 8b
is 766 nm (logꢀ ) 5.14) while that of 8a is 763 nm (logꢀ
) 5.14) revealing that the construction of the dichalco-
genastannole ring affects the UV-vis spectra of phtha-
locyanine.
were prepared as key intermediates in a three-step
process. The phthalonitrile derivatives 5a and 5b were
then treated with lithium in alcohol to produce corre-
sponding phthalocyanines 6a and 6b, respectively, in
moderate yields as dark green solids. X-ray crystal-
lographic analysis showed that the structure of 6a is
somewhat distorted. The absorptions of the Q-band of 6a
and 6b were observed at 755 and 757 nm, respectively,
suggesting that the redshift of the Q-band is more
strongly affected by the substitution of the ethyl group
at the R-positions than that of the chalcogene atoms at
the â-positions. The electrochemical properties of the
phthalocyanines and benzotrichalcogenoles were deter-
mined by cyclic voltammetry with Ag/AgNO3 used as the
reference electrode. The cyclic voltammogram of 6a shows
two reversible oxidation potentials and two reversible
reduction potentials, while the differences in potential
between the first oxidation potential and the first reduc-
tion potential of 6a and 6b are similar in value. Phtha-
locyanine derivatives with four dichalcogenastannole
rings were obtained by the removal of the benzyl group
of 6a and 6b and the stannylation of 7a and 7b. Studies
of further functionalization of 7a and 7b are currently
in progress in our laboratory.
Con clu sion
Compounds 1a and 1b with two adjacent bromine
atoms were first prepared by the reaction of TBDEB with
elemental sulfur or selenium in DBU. To apply 1a and
1b to the construction of phthalocyanine derivatives with
several sulfur or selenium functional groups, 5a and 5b
(21) Ogawa, S.; Ohmiya, T.; Kikuchi, T.; Kawaguchi, A.; Saito, S.;
Sai, A.; Ohyama, N.; Kawai, Y.; Niizuma, S.; Nakajo, S.; Kimura, T.;
Sato, R. J . Organomet. Chem. 2000, 611, 136-145.
(22) Block, E.; Birringer, M.; He, C. Angew. Chem., Int. Ed. 1999,
38, 1604-1606.
(23) (a) Vela´zquez, C. S.; Broderick, W. E.; Sabat, M.; Barrett, A.
G. M.; Hoffman, B. M. J . Am. Chem. Soc. 1990, 112, 7408-7410. (b)
Vela´zquez, C. S.; Fox, G. A.; Broderick, W. E.; Anderson, K. A.;
Anderson, O. P.; Barrett, A. G. M.; Hoffman, B. M. J . Am. Chem. Soc.
1992, 114, 7416-7424. (c) Vela´zquez, C. S.; Baumann, T. F.; Olmstead,
M. M.; Hope, H.; Barrett, A. G. M.; Hoffman, B. M. J . Am. Chem. Soc.
1993, 115, 9997-10003. (d) Baumann, T. F.; Nasir, M. S.; Sibert, J .
W.; White, A. J . P.; Olmstead, M. M.; Williams, D. J .; Barrett, A. G.
M.; Hoffman, B. M. J . Am. Chem. Soc. 1996, 118, 10479-10486. (e)
Michel, S. L. J .; Goldberg, D. P.; Stern, C.; Barrett, A. G. M.; Hoffman,
B. M. J . Am. Chem. Soc. 2001, 123, 4741-4748.
(24) Crystallographic data have been deposited at the Cambridge
Crystallographic Data Centre: the deposition numbers are CCDC
237554 for 6a , 237555 for 1a , 237556 for 1b, 237557 for 2a , and 237558
for 2b.
J . Org. Chem, Vol. 69, No. 14, 2004 4721

Kimura et al.
4,5-Bis(2-cyan oeth ylth io)-3,6-dieth ylph th alon itr ile (4a).
Compound 3a (3.22 g, 6.96 mmol) and CuCN (6.30 g, 70.3
mmol) were placed in a glass reactor, DMF (10 mL) was added
under Ar, and the solution was stirred at 120 °C for 5 h. After
the reactor was cooled, FeCl3‚6H2O (19.2 g, 71.0 mmol) and
trace amounts of aqueous HCl were added, and the solution
was stirred at 70 °C for 15 min. After the reactor was cooled
by the addition of ice-water, the product was extracted with
CHCl3 and the solvent was evaporated. The residue was
purified by column chromatography (Wakogel C-300HG, CHCl3)
to produce 4a in 53% yield (3.75 g): yellow crystals; mp 65-
Exp er im en ta l Section
Oxid a tion P oten tia ls. All measurements were performed
by cyclic voltammetry, using Ag/0.01 M AgNO3 as a reference
electrode, Pt wire as a counter electrode, and glassy carbon
as a working electrode. n-Bu4ClO4 (0.1 M) was used as an
electrolyte, and CH2Cl2, CH3CN and CH3CN/CH2Cl2)1:1 were
used as solvents. The scan rate was 200 mV s-1 for all
measurements.
5,6-Dib r om o-4,7-d iet h ylb en zo[1,2,3]t r it h iole
(1a ).
TBDEB (6.76 g, 15 mmol) and elemental sulfur (4.84 g, 151
mmol) were placed in a glass reactor, and DBU (90 mL) was
added. The solution was stirred for 24 h at 140 °C and then
for 24 h at room temperature. The solution was treated with
an aqueous H2SO4 solution and extracted with CHCl3. After
distillation of the solvent and purification by column chroma-
tography (Wakogel C-300HG, n-hexane) and recrystallization
from Et2O, 1a was obtained in 59% yield (3.44 g); orange
1
67 °C; H NMR (400 MHz, CDCl3) δ 1.29 (t, J ) 7.5 Hz, 6H),
2.68 (t, J ) 6.8 Hz, 4H), 3.28 (q, J ) 7.5 Hz, 4H), 3.32 (t, J )
6.8 Hz, 4H); 13C NMR (101 MHz, CDCl3) δ 15.3, 18.4, 29.0,
32.9, 114.5, 117.2, 117.4, 146.0, 152.8; MS (m/z) 354 (M+); IR
(KBr) 2255, 2230 cm-1 (CN). Anal. Calcd for C18H18N4S2: C,
60.99; H, 5.12; N, 15.80. Found: C, 60.96; H, 5.51; N, 15.53.
4,5-Bis(4-n it r op h en et h ylselen o)-3,6-d iet h ylp t h a lon i-
tr ile (4b). Compound 4b was obtained in 37% yield (1.20 g)
by treatment of 3a (3.75 g, 5.0 mmol) with CuCN (1.82 g, 20
mmol) in DMF (12 mL) at 120 °C for 6 h under Ar: orange
1
crystals; mp 87-87.5 °C; H NMR (400 MHz, CDCl3) δ 1.18
(t, J ) 7.5 Hz, 6H), 2.95 (q, J ) 7.5 Hz, 4H); 13C NMR (101
MHz, CDCl3) δ 12.7, 34.5, 126.6, 138.6, 141.3; MS (m/z) 386
(M+); UV (CHCl3) λmax nm (log ꢀ) 330 (3.1), 282 (4.0), 241 (4.1).
Anal. Calcd for C10H10Br2S3: C, 31.10; H, 2.61. Found: C,
31.43; H, 2.64.
1
crystals; mp 90 °C; H NMR (400 MHz, CDCl3) δ 1.24 (t, J )
7.5 Hz, 6H), 3.10 (t, J ) 7.6 Hz, 4H), 3.24 (q, J ) 7.5 Hz, 4H),
3.28 (t, J ) 7.6 Hz, 4H), 7.35 (d, J ) 8.6 Hz, 4H), 8 12 (d, J )
8.6 Hz, 4H); 13C NMR (101 MHz, CDCl3) δ 15.4, 31.9, 32.7,
36.0, 114.9, 116.0, 123.8, 129.1, 146.5, 146.9, 147.4, 152.1;
77Se NMR (76 MHz, CDCl3) δ 309.9, MS (m/z) 642 (M+); IR
(KBr) 2225 cm-1 (CN). Anal. Calcd for C28H26N4O4Se2: C,
52.51; H, 4.09; N, 8.75. Found: C, 52.18; H, 4.33; N, 8.55.
5,6-Dib r om o-4,7-d iet h ylb en zo[1,2,3]t r iselen ole (1b ).
TBDEB (9.04 g, 20 mmol) was reacted with elemental
selenium (11.1 g, 141 mmol) in DBU (80 mL) at 100 °C for 24
h. The solution was treated with an aqueous H2SO4 solution
under O2 bubbling and extracted with CHCl3. After distillation
of the solvent and purification by column chromatography
(Wakogel C-300HG, n-hexane/CHCl3 ) 1:1), 1b was obtained
4,5-Bis(ben zylth io)-3,6-dieth ylph th a lon itr ile (5a ). Com-
pound 4a (0.495 g, 1.39 mmol) in THF (80 mL)/MeOH (20 mL)
was treated with CsOH‚H2O (0.937 g, 5.58 mmol) at room
temperature. Benzyl bromide (0.5 mL, 4.2 mmol) was then
added, and the solution was stirred for 24 h. After the usual
workup, the product was extracted with CHCl3 and the solvent
was evaporated. The residue was purified by column chroma-
tography (Wakogel C-300HG, CHCl3) to produce 5a in 60%
yield (0.838 g): yellow crystals; mp 142-145 °C; 1H NMR (400
MHz, CDCl3) δ 1.12 (t, J ) 7.5 Hz, 6H), 2.99 (q, J ) 7.5 Hz,
4H), 4.23 (s, 4H), 7.04-7.09 (m, 4H), 7.19-7.23 (m, 6H); 13C
NMR (101 MHz, CDCl3) δ 15.0, 28.6, 42.1, 114.9, 115.8, 127.7,
128.5, 128.8, 136.4, 147.5, 152.7; MS (m/z) 428 (M+); IR (KBr)
2226 cm-1 (CN). Anal. Calcd for C26H24N2S2: C, 72.86; H, 5.64;
N, 6.54. Found: C, 74.74; H, 6.06; N, 6.62.
4,5-Bis(b en zylselen o)-3,6-d iet h ylp h t h a lon it r ile (5b ).
Compound 4b (652 mg, 1.0 mmol) in THF (20 mL)/MeOH (10
mL) was treated with MeONa (227 mg, 4.2 mmol) at 60 °C for
1 h under Ar. Benzyl bromide (0.5 mL, 4.2 mmol) was then
added, and the solution was stirred at 60 °C for 6 h. After the
usual workup, the product was extracted with CHCl3 and the
solvent was evaporated. The residue was purified by column
chromatography (Wakogel C-300HG, CHCl3) to produce 5b in
69% yield (365 mg): orange crystals; mp 150 °C; 1H NMR (400
MHz, CDCl3) δ 1.11 (t, J ) 7.5 Hz, 6H), 3.04 (q, J ) 7.5 Hz,
4H), 4.22 (s, 4H), 6.99-7.04 (m, 4H), 7.14-7.19 (m, 6H); 13C
NMR (101 MHz, CDCl3) δ 15.2, 31.6, 36.5, 115.1, 115.6, 127.4,
128.5, 128.7, 137.2, 147.1, 152.4; 77Se NMR (76 MHz, CDCl3)
δ 389.6; MS (m/z) 524 (M+); IR (KBr) 2224 cm-1 (CN). Anal.
Calcd for C26H24N2Se2: C, 59.78; H, 4.63; N, 5.36. Found: C,
59.45; H, 4.73; N, 5.25.
1
in 54% yield (5.76 g): dark-red crystals; mp 141-142 °C; H
NMR (400 MHz, CDCl3) δ 1.20 (t, J ) 7.5 Hz, 6H), 3.05 (q, J
) 7.5 Hz, 4H); 13C NMR (101 MHz, CDCl3) δ 12.9, 37.9, 127.1,
141.8, 142.4; 77Se NMR (76 MHz, CDCl3) δ 457.5, 576.8 (J Se-Se
) 260 Hz); MS (m/z) 528 (M+). Anal. Calcd for C10H10Br2Se3:
C, 22.80; H, 1.91. Found: C, 22.80; H, 2.10.
1,2-Bis(2-cya n oeth ylth io)-3,6-d ieth yl-4,5-d ibr om oben -
zen e (3a ). To a solution of 1a (2.67 g, 6.91 mmol) in THF (90
mL)/methanol (30 mL) was slowly added NaBH4 (0.567 g, 15
mmol), and the solution was stirred for 30 min. After addition
of K2CO3 (2.06 g, 15 mmol), 3-bromopropionitrile (1.5 mL, 18
mmol) was added, and the solution was stirred at room
temperature for 12 h. After the usual workup, the solution
was extracted with CHCl3 and the solvent was evaporated.
The residue was purified by column chromatography (Wakogel
C-300HG, n-hexane/CHCl3 ) 1:1) to produce 3a in 48% yield
(1.55 g): colorless crystals; mp 95 °C; 1H NMR (400 MHz,
CDCl3) δ 1.19 (t, J ) 7.4 Hz, 6H), 2.63 (t, J ) 7.1 Hz, 4H),
3.23 (t, J ) 7.1 Hz, 4H), 3.37 (q, J ) 7.4 Hz, 4H); 13C NMR
(101 MHz, CDCl3) δ 14.1, 18.1, 32.9, 33.4, 117.9, 130.8, 138.8,
149.6; MS (m/z) 462 (M+); IR (KBr) 2249 cm-1 (CN). Anal.
Calcd for C14H18Br2N2S3: C, 41.57; H, 3.92; N, 6.06. Found:
C, 41.77; H, 3.91; N, 6.11.
1,2-Bis(4-n itr op h en eth ylselen o)-3,6-d ieth yl-4,5-d ibr o-
m oben zen e (3b). Compound 1b (1.72 g, 3.3 mmol), 4-nitro-
phenethyl bromide (3.04 g, 13 mmol), and K2CO3 (1.30 g, 9.4
mmol) were placed in a glass reactor, and THF (20 mL) and
methanol (10 mL) were added. NaBH4 (0.462 g, 12 mmol) was
added slowly, and the solution was stirred at 60 °C for 6 h.
After the usual workup, the solution was extracted with CHCl3
and the solvent was evaporated. The residue was purified by
column chromatography (Wakogel C-400, n-hexane/CHCl3 )
1:1) to produce 3b in 61% yield (1.50 g): colorless crystals;
1,4,8,11,15,18,22,25-Octa eth yl-2,3,9,10,16,17,23,24-(ben -
zylt h io)p h t h a locya n in e (6a ). Lithium (36 mg, 5.2 mmol)
was placed in a glass reactor, n-pentanol (2 mL) was added
under Ar, and the solution was stirred at 100 °C for several
minutes. Compound 5a (215 mg, 0.5 mmol) was added to the
solution, which was then stirred at 100 °C for 1 h. After the
reactor was cooled, aqueous HCl and MeOH were added, and
a green precipitate was filtered out. The residue was purified
by column chromatography (Wakogel C-300HG, n-hexane/
CHCl3 ) 1:1) to produce 6a in 39% yield (84 mg): green
1
mp 95-97 °C; H NMR (400 MHz, CDCl3) δ 1.14 (t, J ) 7.4
Hz, 6H), 3.05 (t, J ) 7.6 Hz, 4H), 3.24 (t, J ) 7.6 Hz, 4H), 3.34
(q, J ) 7.4 Hz, 4H), 7.28 (d, J ) 8.6 Hz, 4H), 8 11 (d, J ) 8.6
Hz, 4H); 13C NMR (101 MHz, CDCl3) δ 14.3, 32.2, 36.2, 36.2,
123.7, 129.1, 129.2, 139.1, 146.7, 148.1, 148.7; 77Se NMR (76
MHz, CDCl3) δ 317.7, MS (m/z) 748 (M+). Anal. Calcd for
1
C
26H26Br2N2O4Se2: C, 41.74; H, 3.50; N, 3.74. Found: C, 41.89;
crystals; mp 82-84 °C; H NMR (400 MHz, CDCl3) δ 1.48 (t,
H, 3.71; N, 3.80.
J ) 7.3 Hz, 24H), 4.45 (s, 16H), 4,60 (q, J ) 7.3 Hz, 16H),
4722 J . Org. Chem., Vol. 69, No. 14, 2004

Preparation of Phthalocyanines
7.11-7.17 (m, 8H), 7.17-7.23 (m, 16H), 7.29-7.33 (m, 16H);
UV (CHCl3) λmax nm (log ꢀ) 755 (5.1); MALDI-TOFMS (m/z)
1714.71 (M+).
to produce 2a in 13% yield (31 mg): orange crystals; mp 169-
170 °C; 1H NMR (400 MHz, CDCl3) δ 1.28 (t, J ) 7.6 Hz, 6H),
2.93 (q, J ) 7.6 Hz, 4H); 13C NMR (101 MHz, CDCl3) δ 13.6,
30.2, 114.2, 114.9, 141.9, 148.0; MS (m/z) 278 (M+); IR (KBr)
2227 cm-1 (CN); UV (CHCl3) λmax nm (log ꢀ) 448 (2.5), 341 (3.5),
299 (4.3), 269 (3.9). Anal. Calcd for C12H10N2S3: C, 51.77; H,
3.62; N, 10.06. Found: C, 51.99; H, 3.75; N, 9.80.
1,4,8,11,15,18,22,25-Octa eth yl-2,3,9,10,16,17,23,24-(ben -
zylselen o)p h th a locya n in e (6b). Compound 6b was obtained
in 25% yield (134 mg) by treatment of 5b (528 mg, 1.0 mmol)
with lithium (35 mg, 5.0 mmol) in n-hexanol (2 mL) at 100 °C
for 2 h under Ar: dark-green powder; mp 75-76 °C; 1H NMR
(400 MHz, CDCl3) δ 1.46 (t, J ) 7.3 Hz, 24H), 4.45 (s, 16H),
4,67 (q, J ) 7.3 Hz, 16H), 7.05-7.11 (m, 8H), 7.12-7.18 (m,
16H), 7.23-7.28 (m, 16H); 77Se NMR (76 MHz, CDCl3) δ 356.0;
UV (CHCl3) λmax nm (log ꢀ) 757 (5.1); MALDI-TOFMS (m/z)
2091.56 (M+).
Deb en zyla t ion of 6b a n d Cycliza t ion of Lit h iu m
Octa th iola te w ith Bu 2Sn Cl2. Compound 6b (106 mg, 0.051
mmol) and lithium (29 mg, 4.1 mmol) were placed in a glass
reactor, THF (5 mL) was added under Ar, and the solution
was cooled to -78 °C. NH3 (30 mL) was introduced into the
reactor (15 min) and was condensed. The solution was stirred
for 45 min at this temperature and gradually warmed to room
temperature. NH3 gas was generated, and Ar gas was intro-
duced into the reactor. After the generation of NH3 was
complete, NH4Cl (268 mg, 5 mmol) was added slowly. Bu2SnCl2
(156 mg, 0.5 mmol) in THF (15 mL)/MeOH (25 mL) was added
to the solution, and the solution was stirred for 1 h at room
temperature. The solution was then evaporated and the
product separated by column chromatography (Wakogel
C-300HG, n-hexane/CHCl3 ) 1:1) to produce 8b in 23% yield
(27 mg): green powder; 1H NMR (400 MHz, CDCl3) δ 0.96 (t,
J ) 7.3 Hz, 24H), 1.42-1.51 (m, 16H), 1.67 (t, J ) 7.3 Hz,
24H), 1.82-1.91 (m, 32H), 4.86 (bs, 16H); 77Se NMR (76 MHz,
CDCl3) δ 82.4; 119Sn NMR (149 MHz, CDCl3) δ 88.2; UV
(CHCl3) λmax nm (log ꢀ) 766 (5.13); MALDI-TOFMS (m/z)
2294.38 (M+).
Deb en zyla t ion of 6a a n d Cycliza t ion of Lit h iu m
Octa selen ola te w ith Bu 2Sn Cl2. Compound 6a (63 mg, 0.037
mmol) was similarly treated as described above [lithium (22
mg, 3 mmol) in THF/NH3, NH4Cl (162 mg, 3 mmol) and Bu2-
SnCl2 (113 mg, 0.37 mmol)] to produce 8a in 17% yield (12
mg): green powder; 1H NMR (400 MHz, CDCl3) δ 0.96 (t, J )
7.3 Hz, 24H), 1.42-1.53 (m, 16H), 1.68 (t, J ) 7.3 Hz, 24H),
1.76-1.94 (m, 32H), 4.80 (bs, 16H); 119Sn NMR (76 MHz,
CDCl3) δ 177.6; UV (CHCl3) λmax nm (log ꢀ) 763 (5.13); MALDI-
TOFMS (m/z) 1919.34 (M+).
5,6-Dicya n o-4,7-d ieth ylben zo[1,2,3]tr ith iole (2a ). Com-
pound 4a (296 mg, 0.84 mmol) in THF (20 mL)/MeOH (5 mL)
was treated with CsOH‚H2O (582 mg, 3.46 mmol) at room
temperature for 2 h. Elemental sulfur (90 mg, 2.8 mmol) was
then added, and the solution was stirred for 12 h. After the
usual workup, the product was extracted with CHCl3 and the
solvent was evaporated. The residue was purified by column
chromatography (Wakogel C-400HG, n-hexane/CHCl3 ) 1:1)
5,6-Dicyan o-4,7-dieth ylben zo[1,2,3]tr iselen ole (2b). Com-
pound 4b (692 mg, 1.08 mmol) in THF (20 mL)/MeOH (10 mL)
was treated with MeONa (225 mg, 4.2 mmol) at 60 °C under
Ar. Amorphous selenium (410 mg, 5.0 mmol) was then added,
and the solution was stirred at 60 °C for 6 h. After the usual
workup, the product was extracted with CHCl3 and the solvent
was evaporated. The residue was purified by column chroma-
tography (Wakogel C-300HG, CHCl3) to produce 2b in 28%
1
yield (127 mg): dark-red crystals; mp 151-152 °C; H NMR
(400 MHz, CDCl3) δ 1.29 (t, J ) 7.6 Hz, 6H), 3.01 (q, J ) 7.6
Hz, 4H); 13C NMR (101 MHz, CDCl3) δ 14.0, 33.2, 114.5, 115.2,
145.2, 150.0; 77Se NMR (76 MHz, CDCl3) δ 463.5, 563.5 (J Se-Se
) 271 Hz); Anal. Calcd for C12H10N2Se3: C, 34.39; H, 2.41; N,
6.68. Found: C, 34.66; H, 2.66; N, 6.65.
1,2-Bis(b e n zylse le n o)-4,5-d ib r om o-3,6-d ie t h ylb e n -
zen e. Compound 1b (2.64 g, 5.0 mmol) and K2CO3 (1.39 g, 10
mmol) were placed in a glass reactor, and THF (40 mL) and
methanol (10 mL) were added under Ar. NaBH4 (0.568 g, 15
mmol) was added slowly, and then benzyl bromide (2.38 mL,
20 mmol) was dropped from syringe. The solution was stirred
for 6 h. After the usual workup, the solution was extracted
with CHCl3 and the solvent was evaporated. The residue was
purified by column chromatography (Wakogel C-400, n-hexane/
CHCl3 ) 1:1) to produce 1,2-bis(benzylseleno)-4,5-dibromo-3,6-
diethylbenzene in 68% yield (2.17 g): colorless crystals; mp
1
83-86 °C; H NMR (400 MHz, CDCl3) δ 1.07 (t, J ) 7.4 Hz,
6H), 3.22 (q, J ) 7.4 Hz, 4H), 4.16 (s, 4H), 7.07-7.13 (m, 4H),
7.15-7.23 (m, 6H); 13C NMR (101 MHz, CDCl3) δ 14.1, 35.9,
36.5, 127.0, 128.3, 128.8, 129.0, 138.1, 140.1, 148.9; 77Se NMR
(76 MHz, CDCl3) δ 390.8; MS (m/z) 630 (M+). Anal. Calcd for
C
22H24Br2Se2: C, 45.74; H, 3.84. Found: C, 45.76; H, 3.95.
Ack n ow led gm en t. We thank Prof. N. Kobayashi
and Dr. T. Fukuda (Tohoku University) for their useful
suggestions. This work was supported by a Grant-in-
Aid for Scientific Research (No. 15550024) from the
Ministry of Education, Science, Sports and Culture,
J apan.
Su p p or tin g In for m a tion Ava ila ble: Crystallographic
1
data of 1a ,b, 2a ,b, and 6a ; UV-vis spectra of 6a and 6b; H
NMR spectra of 6a ,b, and 8a ,b. This material is available free
of charge via the Internet at http://pubs.acs.org.
J O030354J
J . Org. Chem, Vol. 69, No. 14, 2004 4723