Synthesis of 'thianthrene dimer' by the coupling reaction of stannylthianthrenes in the presence of copper catalysts

Article abstract of DOI:10.1016/j.tet.2011.04.057

The coupling reaction of 1-tributylstannylthianthrene (5) and 2-tributylstannylthianthrene (7) in the presence of copper catalysts at rt afforded the thianthrene dimer 1,1′-bithianthrene (3), 2,2′-bithianthrene (8), and 1,2′-dithianthrene (9) in high yields. Also we obtained thianthrene oxide dimer (R,R) (S,S)-1-(10-S-monoxythianthrene- 1-yl)thianthrene-10-S-monoxide (12) and (R,S) (S,R)-1-(10-S-monoxythianthrene-1- yl)thianthrene-10-S-monoxide (13) from 1-tributylstannyl-10-S-monoxythianthrene (10) under the same reaction condition. The final structural conformation of 3, 8, 9, and 12 was performed by X-ray crystallographic analysis. Further, the solvent effects in the coupling reactions were also examined.

Full text of DOI:10.1016/j.tet.2011.04.057

Tetrahedron 67 (2011) 4672e4679
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Tetrahedron
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Synthesis of ‘thianthrene dimer’ by the coupling reaction of stannylthianthrenes
in the presence of copper catalysts
*
*
Hiroyuki Morita , Yasutaka Oida, Takamine Ariga, Satoru Fukumoto, Md. Chanmiya Sheikh ,
*
Takayoshi Fujii, Toshiaki Yoshimura
Department of Applied Chemistry, Faculty of Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
The coupling reaction of 1-tributylstannylthianthrene (5) and 2-tributylstannylthianthrene (7) in the
presence of copper catalysts at rt afforded the thianthrene dimer 1,10-bithianthrene (3), 2,20-bithian-
threne (8), and 1,20-dithianthrene (9) in high yields. Also we obtained thianthrene oxide dimer (R,R) (S,S)-
1-(10-S-monoxythianthrene-1-yl)thianthrene-10-S-monoxide (12) and (R,S) (S,R)-1-(10-S-mon-
oxythianthrene-1-yl)thianthrene-10-S-monoxide (13) from 1-tributylstannyl-10-S-monoxythianthrene
(10) under the same reaction condition. The final structural conformation of 3, 8, 9, and 12 was per-
formed by X-ray crystallographic analysis. Further, the solvent effects in the coupling reactions were also
examined.
Received 25 February 2011
Received in revised form 9 April 2011
Accepted 14 April 2011
Available online 21 April 2011
Keywords:
Thianthrene derivatives
Coupling reaction
Copper catalyst
Ó 2011 Elsevier Ltd. All rights reserved.
Thianthrene dimer
1. Introduction
their sulfur atom under acidic and thermal conditions.8 In the
report, we indicated the inversion of sulfinyl group by sub-
It has been known that thianthrene derivatives are folded
along the SeS axis, and consequently exist as ‘butterfly struc-
tures’, which contain a boat-form similar to a 1,4-dithiin by X-ray
crystallographic analyses for both thianthrene itself and several
oxidized thianthrenes.1e4 To dates, only a limited number of re-
ports in the chemistry of thianthrene, such as its oxidation to
sulfoxides and sulfones, and its imination to derivatives,5 have
appeared in the literatures. Recently, Bonchio et al.6 and Adam
and Golsch7 reported that the importance of steric and electronic
effects on both the rate and the site of further oxidation of
thianthrene or its 5-oxide to their oxides under several oxidation
conditions. From these results, it is envisaged that a direct in-
teraction was operated between the substituents on the two
sulfur atoms both sterically and electronically. Therefore, in the
course of the study of thianthrene derivatives with a regulation
functionality of a new class of functionalized materials, we in-
vestigated cis/trans isomerization of several 5,10-disubstituted
thianthrene derivatives. Recently, we reported the syntheses and
structural analyses of 10-monoxy and dioxy-5-N-substituted
iminothianthrene derivatives and the stereochemical change on
stitution of H2O on the hydroxysulfonium sulfur atom at the 10-
position formed by protonation in the course of hydrolysis in
concentrated H2SO4, which also shows evident that the trans
form seems to be less easily attacked by H2O than the cis form
because of unfavorable steric hindrance by the hydrogen of peri-
position. Hence, we suggested that the interaction between
substituents of peri-position and substituents on sulfur atom
influence the ‘flipeflap’ inversion.
Previously, Lovell and Joule.9a reported on electrophilic aro-
matic substitution of thianthrene under various electrophiles and
the steric effect was found to be important on the reactivity and
regioselectivity in the thianthrene system. To clarify the steric
effects of peri substituents and also neutral interaction of the
conformational change, we have attempted to synthesize thian-
threne derivatives having substituents on peri-position. Recently,
Ogawa et al.9b reported the synthesis of 1,90-disubstituted thian-
threne by Negishi coupling reaction. Meanwhile, on the coupling
reaction of aryl groups,10,11 alkynyl,10 alkenyl,10,12 and vinyl13
groups via stannanes in the presence of Cu(NO3)2$3H2O. It is
well known that the protocols were highly effective and versatile,
another using copper catalysts, such as Cu(NO3)2$3H2O and CuCl,
were used in THF or DMF condition.13,14 In order to reveal the
nature of stannylthianthrene, we have prepared their derivatives,
and studied the coupling reactions in several solvents in the
presence of copper catalyst.
* Corresponding authors. E-mail addresses: moritah@pb.ctt.ne.jp (H. Morita),
chansheikh@yahoo.com (M.C. Sheikh), yosimura@eng.u-toyama.ac.jp (T. Yoshimura).
0040-4020/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2011.04.057

H. Morita et al. / Tetrahedron 67 (2011) 4672e4679
4673
2. Results and discussion
SnBu
1) n-BuLi (1.1 equiv), THF,
3
S
S
S
-78 °C to reflux, 1 h
2.1. Synthesis of stannyl compound 1 and studies the
coupling reaction of 1 in the presence of copper catalysts
2) Bu SnCl (1.3 equiv), THF,
3
S
-78 °C to reflux, 3 h
5 (75%)
2
Dimethylbis(thianthren-1-yl)tin (1) was prepared from thian-
threne (2) where 2 was prepared by the reaction of diphenyl sulfide
with sulfur and AlCl3. Initially, the solution briefly to reflux com-
pleted the lithiation of peri-position nine, which afforded 1 in 82%
yield after successive addition of Me2SnCl2 (Scheme 1).
Scheme 2. Synthesis of stannylthianthrene 5 via the lithiation of 2.
Then, the reactions of 5 were carried out in the presence of
copper catalysts, such as Cu(NO3)2$3H2O, Cu(OTf)2 or CuOTf in THF
at rt under ambient atmosphere. Herein CuOTf was used as a cata-
lyst to compare copper of the monovalent and divalent. The results
are summarized in Table 2.
S
1) n-BuLi (1.1 equiv), THF,
S
S
S
S
S
-78 °C to reflux, 0.5 h
Table 2
SnMe
2
The coupling reaction of 5 in the presence of copper(I) or (II) catalyst
2) Me SnCl (0.6 equiv), THF,
2
2
S
-78 °C to reflux, 0.5 h
SnBu3
S
S
CuX (2.2 equiv)
THF, rt, 0.5 h
S
S
2
+
2
1 (82%)
Scheme 1. Synthesis of stannyl compound 1 via the lithiation of 2.
S
3
5
Subsequently, the coupling reactions of 1 were carried out in the
presence of Cu(NO3)2$3H2O or Cu(OTf)2 in THF at rt under nitrogen
or ambient atmosphere to give 1,10-bithianthrene 3. The results are
shown in Table 1.
Entry
CuX
Yielda (%)
3
2
1
2
3
Cu(NO3)2$3H2O
Cu(OTf)2
CuOTf
54
76
47
41
14
50
Table 1
The coupling reaction of 1 in the presence of copper catalysts
a
Isolated yields (not optimized).
S
S
S
CuX2 (2.2 equiv)
S
THF, rt, 20 h
As shown in Table 2, the coupling reaction in the presence of
Cu(NO3)2$3H2O afforded thianthrene coupling compound 3 in 54%
yield, and also gave destannylated product 2 in 41% yield (entry 1).
The coupling reaction of 5 resulted a better yield and shorter re-
action time in comparison with the case of Table 1. We then ex-
amined the reaction in the presence of Cu(OTf)2 under similar
conditions and the best result was obtained in shorter time (entry
2). The reaction in the presence of CuOTf afforded 2 and 3 in 50%
and 47% yields, respectively (entry 3). The results clearly indicate
that in the case of CuOTf only gave half yield of 3 in comparison
with the case of Cu(OTf)2 (entries 2 and 3). Hence, we compre-
hended that the coupling reaction prefers to copper(II) catalysts to
copper(I) catalysts and it is seems that 5 was easily attacked by
copper catalysts than 1. Using the compound 5 also extremely
shortens the reaction time.
+
+
O
2
1
S
S
S
3
S
4
Entry
CuX2
Atmosphere
Producta (yield%)
3
4
2
1
2
3
Cu(NO3)2$3H2O
Cu(OTf)2
Cu(OTf)2
Ambient
Ambient
Nitrogen
12
23
21
3
47
26
72
15
53
a
Isolated yields (not optimized).
As shown in Table 1, the coupling reaction of 1 in the presence of
Cu(NO3)2$3H2O gave thianthrene dimer 1,10-dithianthrene (3) as
a coupling target compound in 12% yield with 1,10-dithianthrenyl
ether (4) in 3% and destannylated product 2 in 72% yield (entry 1).
The similar reaction in the presence of Cu(OTf)2 gave 2 and 3 in 15%
and 23% yields, respectively. In this case 4 was obtained as a main
product in 47% yield (entry 2). Further, the reaction was also carried
out under nitrogen to give 4 in 26% yield (entry 3). Hence, it is
considered that the oxygen in 4 did not derive from ambient at-
mosphere and 4 is the characteristic product by this reaction in the
presence of Cu(OTf)2. These three reactions gave the target com-
pound 3 in low yields. It is probably due to the difficulty of attacking
to stannyl compound 1 by copper catalysts because of unfavorable
steric hindrance by both side’s thianthrene structures. Therefore, it
is suggested that the stannyl compound, 1-tributylstannylthian-
threne (5)9a seemed to be easily attacked by copper catalysts.
Furthermore, we attempted to synthesize 2,20-dithianthrene (8)
using stepwise route. Initially, we have prepared 2-bromothian-
threne (6)9 by the reaction of 2 with Br2/AcOH in 60% yield, and 6
was lithiated with t-BuLi, and followed by the reaction with
Bu3SnCl to afford 2-tributylstannylthianthrene (7)9a in 56% yield.
Finally, the stannyl compound 7 was employed to synthesize the
compound 8 (Scheme 3). The coupling reaction in the presence of
Cu(NO3)2$3H2O or Cu(OTf)2 gave the target coupling compound 8
in 47% and 74% yields, respectively.
In the Stille coupling reaction, only 1,20-dithianthrene (9) is
expected as a cross-coupling product, therefore we carried out the
reaction of 5 with 6 using Pd(PPh3)4 as a catalyst (Scheme 4). Only
the cross-coupling product 9 was obtained expectedly in 50% yield.
In addition, the cross-coupling reaction between 5 and 7 was
also carried out in the presence of Cu(OTf)2 in THF at rt under
ambient atmosphere (Scheme 5). The ratio of the three products
was estimated by 1H NMR to be found 3: 8: 9¼1.0: 1.8: 1.3. This ratio
also seems to indicate the steric factor on the coupling reaction of
the formed radical. As a result, the steric repulsion at 1-positon of
thianthrene seems to be larger than 2-position.
2.2. Synthesis of stannylthianthrene derivatives (5, 7) and
studied their coupling reaction in the presence of various
copper catalysts
We have prepared stannylthianthrene 5 by the reaction of
lithiated thianthren and Bu3SnCl in 75% yield (Scheme 2).

4674
H. Morita et al. / Tetrahedron 67 (2011) 4672e4679
Table 3
S
Br
S
Br2 (2.0 equiv)
Effect of the solvent on reaction time and yield of the coupling reaction
AcOH, 80 °C, 4 h
S
SnBu
S
3
S
2
S
S
Cu(OTf) (2.2 equiv)
2
6 (60%)
S
S
+ 2
solvent, rt
1) t-BuLi (3.0 equiv), THF,
-78 °C to reflux, 0.5 h
S
3
S
S
SnBu
3
5
6
7
2) Bu3SnCl (1.5 equiv), THF,
-78 °C to reflux, 0.5 h
Entry
Solvent (Z value)
Time (h)
Producta (yield%)
7 (56%)
3
2
1
2
3
4
5
6
7
DMF (68.5)
DMSO (68.4)
Acetone (65.5)
MeOH (83.6)
EtOH (79.6)
CHCl3 (63.2)
H2O (94.6)
0.5
0.5
0.5
0.5
0.5
0.5
0.5
78
78
74
32
59
0
11
10
14
29
33
d
S
S
S
S
CuX2 (2.2 equiv)
THF, rt, 0.5 h
0
d
8
a
Isolated yields (not optimized).
X : (NO ) · 3H O, 47%
3 2
2
(SO CF ) , 74%
3
3 2
reaction time was prolonged the yield of thianthrene dimer 3 was
not good.
Scheme 3. Synthetic path of 2,20-bithianthrene (8) from 2.
We propose that the solvent effects of the reactions were in-
volved in Z value of solvent polarity parameter.15 The lower the Z
value is the better yield of the thianthrene dimer 3 and the shorter
the reaction time. Therefore, the coupling reaction in ethanol (entry
5) gave thianthrene dimer 3 in a better yield and shorter reaction
time in comparison with that in methanol (entry 4). No reaction was
detected using chloroform or water (entries 6 and 7). Based on the
results, we propose that in this coupling reaction, inorganic catalyst
(copper catalyst) and organic compound (5) were required; there-
fore, solubility of both copper catalysts and 5 is necessary to obtain
thianthrene dimer 3 in better yield. In order to obtain the clue, fur-
ther the coupling reaction was carried out in the mixed solvent. The
results are summarized in Table 4. As shown in Table 4, the coupling
reaction in mixed solvent, DMSO/CHCl3 (1:1) gave the thianthrene
dimer 3 in 75% yield (entry 1). Successively, we studied the reaction
in H2O/acetone (1:5) as a mixed solvent to give 3 and 2 in 55% and
30% yield, respectively (entry 2). The compound 3 was obtained in
worse yield than the reaction in only acetone. Increasing the ratio of
water in mixed solvent, H2O/acetone (1:3) gave 3 and 2 in 30% and
41% yields, respectively(entry 3). Thus, we suggest that Zvalue of the
mixed solvent increased when H2O was contained, which decrease
the yield of 3. From these results, it is considered that the coupling
reactions proceeded when both 5 and Cu(OTf)2 were dissolved into
the solvent. Hence, the coupling reaction did not proceed in only
H2O or only chloroform as a solvent (Table 3).
S
S
Pd(PPh ) (10 mol %)
3 4
6
5
+
THF, reflux, 3 h
S
S
9 (50%)
Scheme 4. The coupling reaction of 5 and 6 in the presence of Pd(PPh3)4.
SnBu
3
S
SnBu
+
3
S
Cu(OTf) (4.4 equiv)
2
S
THF, rt, 0.5 h
S
5
7
S
S
S
S
S
S
S
S
S
S
+
+
2.4. Synthesis of thianthrene oxide dimer 12 and 13 from 5
S
S
9
In our initial experiment, we attempted to synthesize the
thianthrene oxide dimers, (R,S) (S,R)-1-(10-S-monoxythianthrene-
1-yl)thianthrene-10-S-monoxide (12) or (R,R) (S,S)-1-(10-S-mon-
oxythianthrene-1-yl)thianthrene-10-S-monoxide (13) from thian-
8
3
1
Product ratio by H NMR analysis (3 : 8 : 9)
= 1.0 : 1.8 : 1.3
Scheme 5. The coupling reaction of 5 and 7 in the presence of Cu(OTf)2.
threne dimer 3. When
3 was allowed to react with 3-
chloroperbenzoic acid (m-CPBA) at 0 ꢀC in CH2Cl2, the reaction
proceed smoothly and crude 1H NMR spectrum showed that the
crude product of their oxide dimers contain an inseparable by-
product. Seeking more convenient and shorter synthetic route we
have finally used the stepwise route. The diastereomeric mixture of
thianthrene oxide dimers, meso 12, and racemic 13 were synthe-
sized by the one step reaction of 1-tributylstannyl-10-S-mon-
oxythianthrene (10) with Cu(OTf)2 in DMF where 10 was prepared
by the oxidation reaction of 5 with m-CPBA at 0 ꢀC temperature
(Scheme 6). The stereomeric assignment was performed as follows:
the compound 12 showed 14 different proton NMR signals while
2.3. Solvent effect in the coupling reaction of 5 in the
presence of copper(II) catalyst
Under the optimized reaction conditions, several solvents were
examined. Table 3 shows the effect of solvent on the Cu(OTf)2e
catalyzed coupling reaction. Inspection of Table 3 clearly shows the
yields of thianthrene dimer, 3 are high and in cases of DMF (entry
1), DMSO (entry 2), and acetone (entry 3) the reaction times were
very short within 30 min. In the case of alcohol solvents, such as
methanol or ethanol was used, the reaction rates were slow and the
starting material 5 remained after 30 min (entry 4). Although the

H. Morita et al. / Tetrahedron 67 (2011) 4672e4679
4675
Table 4
Effect of the mixed solvents on reaction time and yield of the coupling reaction
S
SnBu3
Cu(OTf)2 (2.2 equiv)
solvent, rt
S
S
S
S
+ 2
S
3
5
Entry
Solvent
Producta (yield%)
3
2
1
2
3
DMSO/CHCl3 (1:1)
H2O/acetone (1:5)
H2O/acetone (1:3)
75
55
30
12
30
41
a
Isolated yields (not optimized).
O
S
SnBu
SnBu
3
SnBu
3
3
S
S
a
+
ꢀ
Fig. 1. An ORTEP drawing of 3 (50% probability ellipsoids). Selected bond lengths [A]
S
and angles [ꢀ]: S(1)eC(1), 1.774 (5); S(1)eC(12), 1.764 (4); S(2)eC(6), 1.765 (5); S(2)e
C(7), 1.766 (5); S(3)eC(13), 1.772 (5); S(3)eC(24), 1.768 (5); S(4)eC(18), 1.771 (5); S(4)e
C(19), 1.771 (5); C(11)eC(23), 1.501 (7); C(12)eS(1)eC(1), 101.91 (2); C(6)eS(2)eC(7),
102.37 (2); C(24)eS(3)eC(13), 101.77 (2); C(18)eS(4)eC(19), 101.68 (2).
S
5
S
O
10 (39%)
11 (54%)
S
S
S
S
O
O
S
S
O
S
b
10
+
O
S
12 (41%)
13 (43%)
Scheme 6. Synthesis of thianthrene oxide dimer 12 and 13. Reagents: (a) m-CPBA
(1.0 equiv) in CH2Cl2, 0 ꢀC, 1 h; (b) Cu(OTf)2 (2.2 equiv) in DMF, rt, 30 min.
the compound 13 showed only seven different proton signals to
show C2 symmetry and these R,R or S,S isomer of 13. HRMS of both
compounds showed the same molecular ion. The structure of 12
was confirmed also by X-ray crystallographic analysis.
2.5. X-ray crystallographic analysis of 3, 4, 8, 9, and 12
ꢀ
Since X-ray crystal structures of 3, 4, 8, 9, and 12 are new com-
pounds, hence, the structure of 3, 4, 8, 9, and 12 were confirmed by
single crystal X-ray crystallographic analysis. An ORTEP drawing and
some selected bond lengths and angles are listed in Figs. 1e5.
Fig. 2. An ORTEP drawing of 4 (50% probability ellipsoids). Selected bond lengths [A]
and angles [ꢀ]: S(1)eC(1), 1.768 (3); S(1)eC(12), 1.770 (3); S(2)eC(6), 1.769 (3); S(2)e
C(7), 1.772 (3); S(3)eC(13), 1.777 (3); S(3)eC(24), 1.771 (3); S(4)eC(18), 1.770 (3); S(4)e
C(19), 1.773 (3); O(1)eC(11), 1.393 (3); O(1)eC(23), 1.393 (3); C(1)eS(1)eC(12), 101.0
(1); C(6)eS(2)eC(7), 101.2 (1); C(13)eS(3)eC(24), 100.3 (1); C(18)eS(4)eC(19), 100.4
(1); O(1)eC(11)eC(10), 118.5 (3); O(1)eC(11)eC(12), 120.4 (1); O(1)eC(23)eC(22),
121.6 (3); O(1)eC(23)eC(24), 116.9 (2); C(11)eO(1)eC(23), 117.4 (2).
3. Conclusion
In conclusion, we have prepared thianthrene dimer 3, 8, and 9
from the stannyl compound 5 and 7 by the coupling reaction in the
presence of copper catalysts and thianthrene oxide dimer 12 and 13
were obtained from stannyl oxide compound 10 under the same
condition. Further, the solvent effect in coupling reactions of 5 was
also examined and it was observed that when Z value is lower
the thianthrene dimer 3 was formed in better yield and a short
reaction time. Now we are succeedingly studying the synthesis and
reactivity of thianthrene dimer including heteroatom.
1H NMR (400 MHz) and 13C NMR (100 MHz) spectra were
recorded with a JMN-A400 spectrometer in CDCl3 using TMS as
the internal standard. All the reactions were monitored by TLC,
and the products were separated by column chromatography us-
ing Silica Gel 60 and by preparative-layer chromatography using
Silica Gel 60 PF254 with UV or PMA and DNP detection. Also, silica
gel used for preparative thin layer chromatography (PLC) was
Merck Kieselgel 60 PF254
. Mass spectra were obtained on
a JEOL-JMS-D300 mass spectrometer. Elemental analyses were
performed by using a Yanaco CHN-coder MT-5. The X-ray crys-
tallographic analyses were performed on Rigaku AF7R four-circle
4. Experimental section
4.1. General
difractometer using graphite monochromate Mo K
a radiation.
All reagents were obtained from Wako Pure Chemical Industries
Ltd., Tokyo Kasei Co. Ltd., and Aldrich Chemical Co. All the reagents
were the highest quality and were further purified by distillation,
or re-crystallization.
All melting points were uncorrected using a micro melting
point apparatus. IR spectra were recorded on a HORIBA FT-71
spectrometer.

4676
H. Morita et al. / Tetrahedron 67 (2011) 4672e4679
ꢀ
ꢀ
Fig. 3. An ORTEP drawing of 8 (50% probability ellipsoids). Selected bond lengths [A] and angles [ ]: S(1)eC(1), 1.712 (2); S(1)eC(12), 1.767 (2); S(2)eC(6), 1.755 (2); S(2)eS(7), 1.771
(2); C(3)eC(3 ), 1.485 (4); C(1)eS(1)eC(12), 103.31 (9); C(6)eS(2)eC(7), 103.23 (10); C(2)eC(3)eC(3 ), 121.1 (2); C(3 )eC(3)eC(4), 121.9 (2).
*
*
*
4.2. Lithiation of thianthrene; 1-lithiothianthrene
To a stirred solution of thianthrene 2 (1.00 g, 4.62 mmol) in THF
(35 mL) was added 1.6 M n-BuLi (3.2 mL, 5.09 mmol) at ꢁ78 ꢀC
under N2. After heating to reflux for 30 min, the reaction mixture
was re-cooled to ꢁ78 ꢀC, which was used for the reaction of elec-
trophiles successively.
4.3. Preparation of dimethylbis(thianthren-1-yl)tin (1)
To a stirred solution of thianthren-1-yllithium (4.62 mmol) in
THF (6 mL) was added Bu2SnCl2 (609 mg, 2.77 mmol) at ꢁ78 ꢀC
under N2. After heating at reflux for 30 min, the solvent was
evaporated, and CHCl3 was added. Then, the organic layer was
washed with H2O and aqueous saturated NH4Cl, and dried over
anhydrous MgSO4. After removal of the solvent, the residue was
chromatographed by the column on silica gel with hexane/AcOH
(10:1) to give dimethylbis(thianthren-1-yl)tin 1 (1.10 g, 82%) as
ꢀ
Fig. 4. An ORTEP drawing of 9 (50% probability ellipsoids). Selected bond lengths [A]
and angles [ꢀ]: S(1)eC(1), 1.768 (2); S(1)eC(12), 1.774 (2); S(2)eC(6), 1.774 (2); S(2)e
C(13), 1.765 (2); S(3)eC(13), 1.766 (2); S(3)eC(24), 1.772 (2); S(4)eC(18), 1.773 (2);
S(4)eC(19), 1.767 (2); C(5)eC(16), 1.496 (2); C(1)eS(1)eC(12), 101.59 (8); C(6)eS(2)e
C(7), 101.86 (8); C(13)eS(3)eC(24), 101.05 (8); C(18)eS(4)eC(19), 100.95 (8); C(4)e
C(5)eC(16), 118.6 (2); C(5)eC(16)eC(15), 119.7 (2); C(5)eC(16)eC(17), 121.1 (2); C(6)e
C(5)eC(16), 122.5 (1).
a
colorless solid; mp 129e130 ꢀC (from hexane); 1H NMR
(400 MHz, CDCl3) 0.80 (s, 6H), 7.14e7.25 (m, 8H), 7.33e7.35 (m,
2H), 7.48e7.53 (m, 4H); 13C NMR (100 MHz, CDCl3)
ꢁ5.9, 127.3,
127.6, 127.7, 128.6, 128.7, 129.5, 136.1; IR (KBr) 1373, 748 cmꢁ1
d
d
.
HRMS (EI) calcd for C26H20S4Sn: 577.9470; found: m/z 577.9468.
4.4. Preparation of thianthrene (2)
The suspension of diphenyl sulfide (30.0 g, 0.16 mol) and alu-
minum chloride (21.0 g, 0.16 mol) in ligroin (100 mL) was heated at
80 ꢀC for 5 h. This reaction mixture was quenched with H2O and
extract was dried up in vacuum after removal of the solvent. The
residue was dissolve in CHCl3 and this suspension was filtered with
Celite. Then, the solvent was evaporated and dried under vacuum
and re-crystallization from CH2Cl2/hexane to give thianthrene 2
(15.0 g, 44%) as colorless crystals; mp 153e155 ꢀC (from CH2Cl2/
hexane); 1H NMR (400 MHz, CDCl3)
d 7.20e7.25 (m, 4H), 7.45e7.50
(m, 4H); 13C NMR (100 MHz, CDCl3)
d 127.6, 128.7, 135.5; IR (KBr)
1558, 1540, 1433, 761 cmꢁ1. HRMS (EI) calcd for C12H8S2: 216.0067;
found: m/z 216.0061.
4.5. Preparation of 1,10-dithianthrene (3)
To
a stirred solution of dimethylbis(thianthren-1-yl)tin 1
(100 mg, 0.17 mmol) in THF (0.2 mL) was added Cu(OTf)2 (137 mg,
0.38 mmol) under ambient atmosphere for 30 min at rt. The solvent
was evaporated, and CHCl3 was added. The organic layer was
washed with H2O and dried over anhydrous MgSO4. After removal
of the solvent, the residue was chromatographed on silica gel
preparative plate using hexane/CH2Cl2 (3:1) to give 1,10-dithian-
threne 3 as colorless crystals (15 mg, 21%); mp 249e251 ꢀC (from
ꢀ
Fig. 5. An ORTEP drawing of 12 (50% probability ellipsoids). Selected bond lengths [A]
and angles [ꢀ]: S(1)eC(1), 1.788 (2); S(1)eC(12), 1.786 (3); S(1)eO(1), 1.475 (2); S(2)e
C(6), 1.762 (3); S(2)eC(7), 1.768 (3); C(2)eC(14), 1.499 (3); S(3)eO(2), 1.490 (2); S(3)e
C(13), 1.782 (2); C(24)eS(3) 1.784 (3); S(4)eC(19), 1.753 (3); S(4)eC(18), 1.756 (2);
C(1)eS(1)eO(1), 106.9 (1); C(12)eS(1)eO(1), 108.1 (1); C(1)eS(1)eC(12), 97.3 (1);
C(6)eS(2)eC(7), 101.4 (1); C(13)eS(3)eO(2), 106.4 (1); C(13)eS(3)eC(24), 98.6 (1);
C(24)e S(3)eO(2), 106.7 (1); C(19)eS(4)eC(18), 102.7 (1).
CH2Cl2/diethylether); 1H NMR (400 MHz, CDCl3)
4H), 7.22e7.26 (m, 4H), 7.32 (t, J¼7.6 Hz, 2H), 7.50e7.52 (m, 2H),
d 7.13e7.17 (m,

H. Morita et al. / Tetrahedron 67 (2011) 4672e4679
4677
7.59 (dd, J1¼7.8 Hz, J2¼1.4 Hz, 2H); 13C NMR (100 MHz, CDCl3)
residue was chromatographed on silica gel using hexane to give
d
127.2, 127.5, 127.7, 128.4, 128.5, 129.2, 129.3, 135.6, 135.7, 135.9,
2-tributylstannylthianthrene 7 as a colorless oil (515 mg 56%); 1H
136.0, 140.1; IR (KBr) 1553, 1449, 1429, 1394, 786, 749, 725,
455 cmꢁ1. Anal. Calcd for C24H14S4: C, 66.94; H, 3.28. Found: C,
67.13; H, 3.29.
NMR (400 MHz, CDCl3) d 0.86e0.90 (m, 9H), 1.03e1.07 (m, 6H),
1.26e1.37 (m, 6H), 1.48e1.55 (m, 6H), 7.20e7.24 (m, 2H), 7.30 (dd,
J1¼7.6 Hz, J2¼0.8 Hz, 1H), 7.41e7.50 (m, 3H), 7.55 (s, 1H); 13C NMR
(100 MHz, CDCl3)
d 9.7, 13.6, 27.3, 29.0, 127.5, 128.1, 128.6, 128.7,
4.6. Preparation of 1,10-dithianthrenyl ether (4)
134.9, 135.1, 135.5, 135.7, 135.8, 136.0, 141.8. HRMS (EI) calcd for
C24H34S2Sn: 506.1124; found: m/z 506.1120.
To
a stirred solution of dimethylbis(thianthren-1-yl)tin 1
(100 mg, 0.17 mmol) in THF (0.2 mL) was added Cu(OTf)2 (137 mg,
0.38 mmol) under ambient atmosphere for 30 min at rt. The solvent
was evaporated, and CHCl3 was added. Then, the organic layer was
washed with H2O and dried over anhydrous MgSO4. After removal
of the solvent the residue was chromatographed on silica gel pre-
parative plate using hexane/CH2Cl2 (3:1) to give 1,10-dithianthrenyl
ether 4 as colorless crystals (36.1 mg, 47%); mp 180e181 ꢀC (from
4.10. Preparation of 2,20-dithianthrene (8)
To a stirred solution of 2-tributylstannylthianthrene 7 (79.0 mg,
0.16 mmol) in THF (0.2 mL) was added Cu(OTf)2 (122.9 mg,
0.34 mmol) under ambient atmosphere for 30 min at rt. The solvent
was evaporated, and CHCl3 was added. The organic layer was
washed with H2O, and dried over anhydrous MgSO4. After removal
of the solvent, the residue was chromatographed on silica gel
preparative plate using hexane/CH2Cl2 (3:1) to give 2,20-dithian-
threne 8 as colorless crystals (25.1 mg, 74%); mp 232e234 ꢀC; 1H
CH2Cl2/diethylether); 1H NMR (400 MHz, CDCl3)
J1¼8.0 Hz, J2¼0.8 Hz, 2H), 7.05 (t, J¼7.8 Hz, 2H), 7.12e7.19 (m, 6H),
7.36e7.41 (m, 4H); 13C NMR (100 MHz, CDCl3)
117.2, 124.2, 127.2,
d 6.65 (dd,
d
127.7, 127.8, 128.2, 128.6, 129.1, 134.7, 135.5, 137.4, 153.9; IR (KBr)
1550,1434,1414,1245,1037, 942, 781, 749 cmꢁ1. HRMS (EI) calcd for
C24H14OS4: 445.9927; found: m/z 445.9927.
NMR (400 MHz, CDCl3)
d
7.23e7.27 (m, 4H), 7.41 (dd, J1¼8.2 Hz,
J2¼1.8 Hz, 2H), 7.47e7.53 (m, 6H), 7.66 (d, J¼2.0 Hz, 2H); 13C NMR
(100 MHz, CDCl3)
d 126.2, 127.0, 127.8, 127.8, 128.7, 128.8, 129.0,
135.1, 135.2, 135.4, 136.4, 139.4; IR (KBr) 1529, 1442, 1353, 806, 756,
407 cmꢁ1. Anal. Calcd for C24H14S4: C, 66.94; H, 3.29. Found: C,
65.65; H, 3.56.
4.7. Preparation of 1-tributylstannylthianthrene (5)
To a stirred solution of thianthren-1-yllithium (4.62 mmol) in
THF (6 mL) was added Bu3SnCl (1.5 mL, 5.54 mmol) at ꢁ78 ꢀC under
N2. After heating at reflux for 3 h, the solvent was evaporated and
CHCl3 was added. Then, the organic layer was washed with H2O and
aqueous saturated NH4Cl, and dried over anhydrous MgSO4. After
removal of the solvent, the residue was chromatographed on silica
gel using hexane to give 1-tributylstannylthianthrene 5 as a color-
4.11. Preparation of 1,20-dithianthrene (9)
To a stirred solution of 1-tributylstannylthianthrene 5 (30.0 mg,
0.06 mmol) and 2-bromothianthrene 6 (24.0 mg, 0.08 mmol) in
THF (10 mL) was added Pd(PPh3)4 (6.9 mg, 0.01 mmol) at reflux
under N2 for 3 h. The reaction mixture was filtered and CHCl3 was
added. The organic layer was washed with H2O, and dried over
anhydrous MgSO4. After removal of the solvent, the residue was
chromatographed on silica gel preparative plate using hexane/
CH2Cl2 (3:1) to give 1,20-dithianthrene 9 as colorless crystals
(12.8 mg, 50%); mp 163 ꢀC (from CH2Cl2/diethylether); 1H NMR
less oil (1.75 g, 75%); 1H NMR (400 MHz, CDCl3)
d
0.88 (t, J¼7.4 Hz,
9H), 1.17e1.24 (m, 6H), 1.29e1.39 (m, 6H), 1.53e1.61 (m, 6H),
7.16e7.25 (m, 3H), 7.33e7.35 (m, 1H), 7.45e7.53 (m, 3H); 13C NMR
(100 MHz, CDCl3)
d 11.1, 13.6, 27.3, 29.1, 126.9, 127.5, 127.6, 128.4,
128.5, 128.9, 135.2, 135.7, 136.2, 136.5, 143.3, 144.2; IR (KBr) 2956,
2925, 1449 cmꢁ1. HRMS (EI) calcd for C24H34S2Sn: 506.1124; found:
m/z 506.1095.
(400 MHz, CDCl3)
d
7.18e7.30 (m, 7H), 7.36 (dd, J1¼7.6 Hz, J2¼1.6 Hz,
1H), 7.48e7.54 (m, 5H), 7.57 (d, J¼8.0 Hz, 1H); 13C NMR (100 MHz,
CDCl3)
d 127.2, 127.6, 127.8, 127.9, 128.2, 128.5, 128.6, 128.7, 128.8,
4.8. Preparation of 2-bromothianthrene (6)
128.9, 129.1, 129.4, 134.9, 135.1, 135.4, 135.5, 135.6, 135.7, 136.2,
139.8,140.9; IR (KBr) 3047,1438, 751 cmꢁ1. Anal. Calcd for C24H14S4:
C, 66.94; H, 3.28. Found: C, 65.62; H, 3.90.
Br2 (0.3 mL, 4.85 mmol) was added dropwise to a stirred sus-
pension of thianthrene 2 (509 mg, 2.35 mmol) in AcOH (10 mL) at rt
under N2. After the addition was completed the mixture was
allowed to warm to 80 ꢀC, and the resulted brown solution was
stirred for 4 h. Then, the solvent was evaporated and dried in vacuo,
the residue was chromatographed on silica gel using hexane and
re-crystallized from hexane to give 2-bromothianthrene 6 as a col-
orless solid (416 mg, 60%); mp 87e89 ꢀC (from hexane); 1H NMR
4.12. Oxidation of 1-tributylstannylthianthrene (5) with 3-
chloroperbenzoic acid (m-CPBA)
To a stirred solution of 1-tributylstannylthianthrene 5 (214 mg,
0.42 mmol) in CHCl3 (6 mL) was added m-CPBA (73.0 mg,
0.42 mmol) and the reaction mixture was stirred for 1 h at 0 ꢀC and
quenched with water. Then, CHCl3 was added and the organic layer
was washed with H2O, and dried over anhydrous MgSO4. After
removal of the solvent, the residue was purified by column chro-
matography on silica gel using hexane/AcOEt (10:1) to give
1-tributylstannyl-10-S-monoxythianthrene 10 (85.1 mg, 39%) and
1-tributylstannyl-5-S-monoxythianthrene 11 (120 mg, 54%).
(400 MHz, CDCl3) d 7.23e7.26 (m, 2H), 7.30e7.36 (m, 2H), 7.45e7.48
(m, 2H), 7.62 (d, J¼2.0 Hz, 1H); 13C NMR (100 MHz, CDCl3)
d 121.4,
127.9, 127.9, 128.8, 128.8, 129.6, 130.6, 131.2, 134.7, 134.8, 135.2,
137.8; IR (KBr) 1420, 1070 cmꢁ1. HRMS (EI) calcd for C12H7BrS2:
293.9173; found: m/z 293.9171.
4.9. Preparation of 2-tributylstannylthianthrene (7)
To
a
stirred solution of 2-bromothianthrene
6
(358 mg,
4.12.1. 1-Tributylstannyl-10-S-monoxythianthrene
(10). Colorless
0.86 (t, J¼7.2 Hz, 9H), 1.14e1.18 (m,
1.82 mmol) in THF (35 mL) at rt under N2 was added 1.7 M t-BuLi
(3.2 mL, 5.45 mmol). After heating at reflux for 30 min, the
reaction mixture was cooled to rt. To thianthren-2-yllithium was
added Bu3SnCl (0.7 mL, 2.72 mmol). After heating at reflux for 3 h,
the solvent was evaporated, and CHCl3 was added. The organic
layer was washed with H2O and aqueous saturated NH4Cl, and
dried over anhydrous MgSO4. After removal of the solvent, the
oil; 1H NMR (100 MHz, CDCl3)
d
6H), 1.27e1.37 (m, 6H), 1.48e1.58 (m, 6H), 7.32e7.37 (m, 1H), 7.41
(td, J1¼7.6 Hz, J2¼0.9 Hz, 1H), 7.52 (td, J1¼7.6 Hz, J2¼0.9 Hz 1H), 7.61
(dd, J1¼7.6 Hz, J2¼1.2 Hz, 1H), 7.63 (dd, J1¼7.8 Hz, J2¼1.0 Hz, 1H),
7.67 (dd, J1¼7.2 Hz, J2¼1.2 Hz, 1H), 7.84 (dd, J1¼8.0 Hz, J2¼1.2 Hz,
1H); 13C NMR (CDCl3, 100 MHz)
d 13.1, 13.7, 27.4, 29.2, 124.1, 128.0,
128.6, 128.9, 129.0, 129.3, 129.4, 129.6, 137.0, 140.4, 141.9, 145.1; IR

4678
H. Morita et al. / Tetrahedron 67 (2011) 4672e4679
(KBr) 2954, 2919, 1443, 1075, 753 cmꢁ1. HRMS (EI) calcd for
C24H34OS2Sn: 522.1073; found: m/z 522.1053.
group P1 (#2); lattice parameters: a¼10.209 (4) A; b¼21.182 (6) A,
ꢀ
ꢀ
¼97.65 (3)ꢀ,
b¼111.03 (2),
g
¼97.17 (3); V¼1995
ꢀ
c¼10.155 (4) A;
a
3
(1) A ; Z¼4;
m (Mo Ka
)¼4.83 cmꢁ1; 12,221 reflections measured,
ꢀ
4.12.2. 1-Tributylstannyl-5-S-monoxythianthrene (11). Colorless oil;
505 unique (Rint¼0.047); final R value 0.058. The maximum and
1H NMR (400 MHz, CDCl3)
d
0.88 (t, J¼7.2 Hz, 9H), 1.19e1.24 (m,
minimum peaks on the final difference Fourier map corresponded
3
ꢁ ꢀ
6H), 1.29e1.38 (m, 6H), 1.51e1.60 (m, 6H), 7.40 (td, J1¼7.6 Hz,
to 0.26 and ꢁ0.27 e /A , Crystallographic data have been deposited
J2¼1.2 Hz, 1H), 7.43e7.59 (m, 4H), 7.85e7.88 (m, 1H), 7.91 (dd,
with the Cambridge Crystallographic Data Centre, CCDC No. 674017.
J1¼7.8 Hz, J2¼1.0 Hz, 1H); 13C NMR (100 MHz, CDCl3)
d 11.0, 13.6,
27.3, 29.0, 124.1, 124.2, 127.6, 128.3, 128.7, 128.9, 129.5, 135.9, 137.5,
141.2,142.3,144.9; IR (KBr) 2955, 2925,1442,1081, 753 cmꢁ1. HRMS
(EI) calcd for C24H34OS2Sn: 522.1073; found: m/z 522.1072.
4.14.2. 1,10-Dithianthrenyl ether (4). X-ray crystal data; empirical
formula: C24H14OS4; formula weight 446.61; crystal system¼
ꢀ
triclinic; space group P1 (#2); lattice parameters: a¼11.290 (3) A;
ꢀ
ꢀ
a
b¼12.198 (2) A, c¼8.240 (2) A;
¼92.70 (2)ꢀ,
b
¼93.33 (2), ¼117.65
g
3
ꢀ
4.13. Coupling reaction of 1-tributylstannyl-10-S-monoxy-
thianthrene (10) using Cu(OTf)2
(3); V¼1000.0 (5) A ; Z¼2;
m (Mo Ka
)¼4.89 cmꢁ1; 6123 reflections
measured, 318 unique (Rint¼0.039); final R value 0.048. The maxi-
mum and minimum peaks on the final difference Fourier map
3
ꢁ ꢀ
To a stirred solution of 1-tributylstannyl-10-S-monoxythianthrene
10 (30 mg, 0.06 mmol) in DMF (0.1 mL) was added Cu(OTf)2 (45.8 mg,
0.13 mmol) and the reaction mixture was stirred for 0.5 h under am-
bient atmosphere and quenched with water. Then, CHCl3 was added
and the organic layer was washed with H2O, and dried over anhydrous
MgSO4. After removal of the solvent, the residue was chromato-
graphed on silica gel preparative plate using AcOEt/CHCl3 (10:1) to
give (R,S) (S,R)-1-(10-S-monoxythianthrene-1-yl)thianthrene-10-S-
monoxide 12 (5.4 mg, 41%) and (R,R) (S,S)-1-(10-S-mon-
oxythianthrene-1-yl)thianthrene-10-S-monoxide 13 (5.6 mg, 43%).
corresponded to 0.26 and ꢁ0.27 e /A , Crystallographic data have
been deposited with the Cambridge Crystallographic Data Centre,
CCDC No. 674016.
4.14.3. 2,20-Bithianthrene (8). X-ray crystal data; empirical formula:
C24H14S4; formulaweight 430.61; crystal system¼monoclinic; space
ꢀ
ꢀ
group P1 (#14); lattice parameters: a¼11.118 (5) A; b¼6.262 (3) A,
3
ꢀ
ꢀ
c¼14.400 (2) A;
b
¼106.65 (2); V¼960.5 (5) A ; Z¼4;
m
(Mo K
a
)¼
10.04 cmꢁ1; 3188 reflections measured, 127 unique (Rint¼0.037);
final R value 0.051. The maximum and minimum peaks on the final
3
ꢁ ꢀ
difference Fourier map corresponded to 0.23 and ꢁ0.16 e /A ,
Crystallographic data have been deposited with the Cambridge
Crystallographic Data Centre, CCDC No. 674019.
4.13.1. (R,S) (S,R)-1-(10-S-Monoxythianthrene-1-yl)thianthrene-10-
S-monoxide (12). Colorless crystals; mp 291e293 ꢀC (from CH2Cl2/
hexane); 1H NMR (400 MHz, CDCl3)
d
7.23 (dd, J1¼1.2 Hz, J2¼7.6 Hz,
1H), 7.36e7.40 (m, 2H), 7.48e7.56 (m, 3H), 7.59e7.65 (m, 2H), 7.69
(dd, J1¼1.2 Hz, J2¼7.6 Hz, 1H), 7.75e7.79 (m, 2H), 7.83 (dd, J1¼1.6 Hz,
J2¼7.8 Hz, 1H), 7.75e7.79 (m, 2H); 13C NMR (100 MHz, CDCl3)
4.14.4. 1,20-Dithianthrene (9). X-ray crystal data; empirical for-
mula: C24H14S4; formula weight 430.61; crystal system¼triclinic;
ꢀ
space group P1 (#2); lattice parameters: a¼10.714 (2) A; b¼12.588
¼104.14 (2)ꢀ,
b
¼102.30 (1),
g
¼92.02 (2);
ꢀ
ꢀ
d
127.3, 127.4, 127.5, 128.3, 128.6, 129.1, 129.3, 129.5, 129.7, 130.1,
(3) A, c¼7.775 (1) A;
a
3
)¼4.88 cmꢁ1
; 6053 reflections
ꢀ
130.2, 130.3, 130.4, 130.6, 131.4, 131.6, 131.9, 132.6, 133.2, 134.0,
V¼989.2 (3) A ; Z¼2;
m
(MoK
a
135.8, 136.9, 139.9, 140.1; IR (KBr) 1558, 1540, 1028, 668, 611 cmꢁ1
.
measured, 253 unique (Rint¼0.035); final R value 0.051. The maxi-
HRMS (EI) calcd for C24H14O2S4: 461.9877; found: m/z 461.9874.
mum and minimum peaks on the final difference Fourier map
3
ꢁ ꢀ
corresponded to 0.29 and ꢁ0.18 e /A , Crystallographic data have
been deposited with the Cambridge Crystallographic Data Centre,
CCDC No. 674020.
4.13.2. (R,R) (S,S)-1-(10-S-Monoxythianthrene-1-yl)thianthrene-10-
S-monoxide (13). Colorless crystals; mp 298e300 ꢀC (from CH2Cl2/
hexane); 1H NMR (400 MHz, CDCl3)
d 7.32 (m, 4H), 7.52e7.56 (m,
2H), 7.62e7.63 (m, 4H), 7.80 (d, J¼7.6 Hz, 2H), 7.87e7.91 (m, 2H); 13C
4.14.5. (R,S) (S,R)-1-(10-S-Monoxythianthrene-1-yl)thianthrene-10-
S-monoxide (12). X-ray crystal data; empirical formula:
C24H14O2S4; formula weight 462.61; crystal system¼monoclinic;
NMR (100 MHz, CDCl3) d 127.3,128.6,129.2,130.3,130.6,130.6,131.7,
133.2, 133.3, 136.0, 140.0; IR (KBr) 1551, 1559, 1034, 754, 668 cmꢁ1
.
ꢀ
HRMS (EI) calcd for C24H14O2S4: 461.9877; found: m/z 461.9853.
4.14. X-ray crystal structure analysis of 3, 4, 8, 9, and 12
The single crystals were obtained by re-crystallization from
space group C2/c(#15); lattice parameters: a¼36.36 (2) A; b¼7.682
3
ꢀ
ꢀ
ꢀ
(3) A, c¼15.68 (1) A;
b
¼107.18 (1), V¼4184 (5) A ; Z¼7;
m
(Mo K
a
)¼
4.14 cmꢁ1; 6630 reflections measured, 271 unique (Rint¼0.040);
final R value 0.053. The maximum and minimum peaks on the final
3
ꢁ ꢀ
difference Fourier map corresponded to 0.57 and ꢁ0.25 e /A ,
Crystallographic data have been deposited with the Cambridge
Crystallographic Data Centre, CCDC No. 674018.
hexane/CH2Cl2. Diffraction data were measured with
technique at 296 K on a Rigaku AFC7R diffractometer using graphite
monochromated Mo K radiation (
¼0.7107). The data were cor-
u
ꢁ2
q scan
a
l
rected for Lorentz and polarization effects. The respective structure
were solved by using direct methods (SIR 92)16 and expanded using
Fourier techniques (DIRDIF).17 The non-hydrogen atoms were re-
fined anisotropically. Hydrogen atoms were included but not re-
fined. All calculations were performed using the teXsan
crystallographic software package of Molecular Structure Corpo-
ration (1985) and (1999). Crystallographic data analysis has been
deposited with the Cambridge Crystallographic Data Centre as
supplementary publication no. CCDC No. 674016e674020, for 3, 4,
8, 9, and 12. Copies of the data can be obtained free of charge on
application to CCDC, 12 Union Road, Cambridge CB21EZ, UK (fax:
(þ44) 1223 336 030; e-mail: deposite@ccdc.cam.ac.uk).
Supplementary data
Supplementary data associated with this article can be found in
online version at doi:10.1016/j.tet.2011.04.057.
References and notes
1. Lynton, H.; Cox, E. G. J. Chem. Soc. 1956, 9, 4886.
2. (a) Row, I.; Post, B. Acta Crystallogr. 1956, 9, 827; (b) Row, I.; Post, B. Acta
Crystallogr. 1958, 11, 372.
3. (a) Hosoya, S.; Wood, R. G. Chem. Ind. (London) 1957, 1042; (b) Hosoya, S. Chem.
Ind. (London) 1958, 159; (c) Hosoya, S. Chem. Ind. (London) 1958, 980; (d) Ho-
soya, S. Acta Crystallogr. 1963, 16, 310.
4. Howell, P. A.; Curtis, R. M.; Lipxcomb, W. N. Acta Crystallogr. 1954, 7, 498.
5. (a) Stoss, P.; Satzinger, G. Tetrahedron Lett. 1974, 23, 1973; (b) Tamura, Y.; Su-
moto, K.; Matsushima, H.; Taniguchi, H.; Ikeda, M. J. Org. Chem. 1973, 38, 4324;
(c) Tamura, Y.; Matsushima, H.; Minamikawa, J.; Ikeda, M.; Sumoto, K.
4.14.1. 1,10-Bithianthrene (3). X-ray crystal data; empirical formula:
C24H14S4; formula weight 430.61; crystal system¼triclinic; space

H. Morita et al. / Tetrahedron 67 (2011) 4672e4679
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