A straightforward double intramolecular cyclization of dibenzyl dichalcogenols into a triple bond

Article abstract of DOI:10.1016/j.tet.2010.04.101

The intramolecular cyclizations of four types of dibenzyl chalcogenols, which contained one or two ethynyl groups, were carried out. Either the double 5-exo or 6-endo-dig mode ring closure reaction regio- and stereoselectively proceeded to give the corres

Full text of DOI:10.1016/j.tet.2010.04.101

Tetrahedron 66 (2010) 5149e5157
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A straightforward double intramolecular cyclization of dibenzyl dichalcogenols
into a triple bondq
,
a
a
a
b
Haruki Sashida a , Mamoru Kaname , Akemi Nakayama , Hirokazu Suzuki , Mao Minoura
*
a Faculty of Pharmaceutical Sciences, Hokuriku University, Kanagawa-machi, Kanazawa 920-1181, Japan
b Department of Chemistry, School of Science, Kitasato University, 1-15-1 Kitasato, minami-ku, Sagamihara, Kanagawa 252-0373, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
The intramolecular cyclizations of four types of dibenzyl chalcogenols, which contained one or two
ethynyl groups, were carried out. Either the double 5-exo or 6-endo-dig mode ring closure reaction
regio- and stereoselectively proceeded to give the corresponding symmetrical bis(benzo[c]chalcogeno-
phene) or bis(isochromene) derivatives from the dibenzyl chalcogenols having a diyne moiety. In con-
trast, the regioselective tandem 5-exo-dig mode intramolecular ring closure reactions of dibenzyl thiol
and selenol having a mono-yne into a triple bond gave the trans-biisobenzothiophene and selenophene
as the sole product. However, the similar cyclization of dibenzyl tellurol proceeded in both tandem 5-exo
and 6-endo-dig modes to afford the trans-biisobenzotellurophene and ditellurachrysene in good yields
with the ratio of 1:1. The X-ray structural analysis of these novel compounds is also presented.
Ó 2010 Elsevier Ltd. All rights reserved.
Received 15 January 2010
Received in revised form 23 April 2010
Accepted 26 April 2010
Available online 29 April 2010
Keywords:
Intramolecular cyclization
6-endo-dig Mode
5-exo-dig Mode
Triple bond
Benzyl chalcogenol
1. Introduction
tellurols 2B into a triple bond. The 6-endo-dig mode cyclization
was the preferential reaction during the intramolecular trans-
Styrylthiophenes (phenylthienylethenes)2 having a donor or an
acceptor substituent on the benzene and thiophene ring are known
to behave as good nonlininear optical (NLO) chromophores. Sym-
metrical and unsymmetrical bridged diarylethenes3 with hetero-
cyclic aryl groups, such as thiophene and benzothiophene, display
attractive chemical properties for use in molecular switches and
molecular motors.
addition of the selenols or tellurols to an acetylenic moiety
having an alkyl group, while the 5-exo-dig mode benzo[c]chal-
cogenophenes 4 were the main product in the case of the
existence of a phenyl group at the triple bond. Moreover, the
lithiation of 2,20-dibromodiphenylacetylene 5 followed by chal-
cogen insertion resulted in tandem intramolecular ring closure
to give the [1]benzochalcogeno[3,2-b][1]benzochalcogenophenes
6 (Scheme 1).7
Tobe and co-workers4 recently determined that the flash vac-
uum pyrolysis of 1,6-diphenyl-1,5-hexadien-3-ynes yielded the
chrysene4a through the tandem 6-endo cyclization, and the bridged
phenylthienylethenes and dithienylethenenes4b were regio- and
stereoselectively produced by the Pd-catalyzed 5-exo cyclization of
the 1,5-hexadien-3-ynes.5 To the best of our knowledge, there is no
report on the preparation of the bridged heteroarylethene de-
rivatives containing a chalcogen element except for sulfur and the
heterochrysenes.
R
R
R
+
M
M
6-endo-dig
3
X
5-exp-dig
1: X = Br
4
NaMH
2: X = MH
A: M = Se
B: M = Te
On the other hand, we have also reported the general
method for the preparation6 of the isoselenochromenes 3A and
isotellurochromenes 3B together with the (Z)-1-methylidene-2-
Br
1) t-BuLi
2) M
M
indanes
4 containing selenium and tellurium atoms via an
intramolecular cyclization reaction of the benzyl selenols 2A and
M = S, Se, Te
M
Br
q
See Ref. 1.
5
6
* Corresponding author. Tel.: þ81 76 229 6211; fax: þ81 76 229 2781; e-mail
Scheme 1.
address:h-sashida@hokuriku-u.ac.jp (H. Sashida).
0040-4020/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2010.04.101

5150
H. Sashida et al. / Tetrahedron 66 (2010) 5149e5157
As an extension of our ongoing work8 in which we succeeded in
of 7 and 1,5-hexadiyne 11 in 83% yield using the Sonogashira pro-
tocol, followed by bromination to give 13. After several un-
successful attempts10 at the coupling reactions of the o-iodobenzyl
alcohol 7 with the 1,3-butadiyne derivatives11 for the synthesis of
15, we were successful by employing the self-coupling reaction of
the o-trimethylsilyl(TMS)ethynylbenzyl alcohol 14. Compound 14,
when subjected to a reaction with Cu(OAc)2 monohydrate in pyri-
dine/MeOH12 as a solvent at 100 ꢀC, directly led to the diyne 15
along with removal of the TMS group in 78% yield. The reaction of
the o-iodobenzyl alcohol 7 with o-ethynylbenzyl alcohol 17, which
was easily prepared by treatment of the TMS-ethynyl derivative 146
with K2CO3 in MeOH, gave the desired dibenzyl alcohol 18 under
the Sonogashira coupling reaction conditions in 84% yield. 15 and
18 were then readily brominated to give the corresponding bro-
mides 16 and 19 in 64% and 58% yields, respectively.
preparing the various types of five- to nine-membered heterocycles
containing a chalcogen element using the intramolecular cycliza-
tion reaction of the chalcogenols into a triple bond, we decided to
develop a procedure for the double or tandem intramolecular cy-
clizations of dibenzyl chalcogenols into an ethynyl moiety. In this
cyclization reaction, there are three possible types of ring-closure
modes: (i) double 6-endo mode; (ii) double 5-exo mode; and (iii) 6-
endo and 5-exo mode. This finding led us to examine the possible
intramolecular ring closure of the dibenzyl chalcogenols into a tri-
ple bond for synthesizing the novel heterocyclic systems.
2. Results and discussion
2.1. Synthesis of o-ethynyldibenzyl dibromides
The preparation of the starting key o-ethynyldibenzyl bromides
10, 13, 16, 19 is shown in Scheme 2. The Sonogashira Pd-catalyzed
2.2. Cyclization of dibenzyl dichalcogenols
coupling reaction9 of o-iodobenzyl alcohol
7
and 1,4-dieth-
First, in order to prepare the dibenzyl chalcogenols 20, pre-
cursors for the cyclization reaction, we examined the reaction of
the dibenzyl bromide 10, having a benzene ring between two triple
bonds, with the sodium hydrogen chalcogenides (NaHM). The
treatment of the dibromide 10 with 1.5 equiv of the commercially
ynylbenzene 810 with the appropriate modification gave the
desired dibenzyl alcohol 9 in 72% yield. The benzyl alcohol 9 was
readily brominated with PBr3/pyridine to give the key compound
10 in 94% yield. Compound 12 was also synthesized by the reaction
H
X
H
8
PdCl2(Ph3P), CuI
benzene-piperidine
72%
X
9
: X = OH
I
PBr3, pyridine
94%
10: X = Br
OH
H
7
X
H
11
PdCl2(Ph3P), CuI
benzene-piperidine
83%
X
12
: X = OH
PBr3, pyridine
76%
13: X = Br
X
TMS
Cu(OAc)2
OH
pyridine-MeOH
78%
14
X
15
: X = OH
PBr3, pyridine
64%
K2CO3, MeOH
93%
16: X = Br
I
X
H
OH
7
X
OH
PdCl2(Ph3P), CuI
17
benzene-piperidine
84%
18
: X = OH
PBr3, pyridine
58%
19: X = Br
Scheme 2.

H. Sashida et al. / Tetrahedron 66 (2010) 5149e5157
5151
Next, the reactions of the bis-benzyl bromide 13, in which two
ethynyl groups are linked by the ethylene moiety, with NaHS,
NaHSe, and NaHTe were carried out. Compound 13 regioselectively
reacted with NaHS in DMF to afford the bis(isothiochromenyl)
ethane 26a, which was the 6-endo, 6-endo mode cyclization prod-
uct, in 66% yield as the sole product. The treatment of 13 with
NaHSe under similar conditions at room temperature gave the
fourteen-membered diselenide 27b in 70% yield. When we simi-
larly examined the reaction of compound 13 with NaHTe, this re-
action directly led to the thirteen-membered telluride 28c in 82%
yield. The formation of 27b and 28c may proceed via the dibenzyl
chalcogenol intermediates 25, which might undergo intra-
molecular oxidative coupling to produce the diselenide 27b, and
then 28c is generated by eliminating one tellurium atom from the
ditelluride 27c (path a). Alternatively, compound 28c was directly
obtained by the intramolecular coupling of the initial mono-tellurol
24c via path b. When the reaction of 13 with NaHSe was carried out
at 110e115 ꢀC, the 6-endo, 6-endo mode cyclization reaction was
found to proceed giving the isoselenochromene derivative 26b in
61% yield. However, the similar reaction of 13 with NaHTe produced
a complex mixture without affording the corresponding 6-endo
mode ring closure product 26c, probably because of its thermal
instability.
The behavior of these cyclization reactions of the benzyl chal-
cogenols shown in Schemes 3 and 4 were found to be dependent
upon substitution on the triple bond, and is essentially similar to
that of the mono benzyl chalcogenols Scheme 5.6
The 5-exo mode ring closure reaction is predominant in the
intramolecular addition of the dibenzyl chalcogenols to an acety-
lenic moiety having a phenyl ring. On the contrary, the 6-exo mode
cyclization compounds were the main product for the case of an
ethylene moiety present at the triple bond.
Moreover, the dibenzyl bromide 16 having a conjugated diyne
reacted with NaHS and NaHSe under the conditions described above
to give the 5-exo mode cyclization products, the benzo[c]thiophene
31a and benzo[c]selenophene 31b, via the certain chalcogenol in-
termediates 30 in 73 and 89% yields, respectively. The desired tellur-
ophene 31c was obtained in this cyclization reaction in only 15% yield
together with the mono 5-exo cyclized product 32 in 83% yield, while
the 6-endo mode cyclization reaction did not proceed. The un-
expected formation of 32, in which one benzyl tellurol (or bromide)
may be reduced to a methyl group without cyclization, cannot be
clearly explained in detail, while 31c was not converted to 32 under
the cyclization conditions. The (Z)-regiochemistry of the olefin
moiety of 31 was determined by X-ray single crystallography using
HM
Br
NaHM
MH
20
Br
10
5-exo, 6-endo
5-exo, 5-exo
6-endo, 6-endo
M
M
M
21
M
M
a M = S (80%)
b M = Se (88%)
c M = Te (81%)
M
22
23
Scheme 3.
available NaHS hydrate in DMF at room temperature resulted in the
direct ring closure to give the benzo[c]thiophene derivative 21a in
80% yield without any characterized products. Compound 21a can
be produced by the tandem 5-exo mode cyclization of the specific
benzyl thiol intermediate 20a at the sp. carbon atom of the triple
bond with excellent regio- and stereoselectivity. However, the re-
action of 10 with 1.5 equiv of NaHSe,13 which was freshly prepared
from selenium dust and NaBH4 in dry DMF, gave a complex mixture
including the desired benzo[c]selenophene 21b in poor yield.
When the dibromide 10 was treated with NaHSe, followed by ad-
dition of ethanol as a proton source after the disappearance of the
starting dibromide, 21b was formed in 88% yield as the sole prod-
uct. In the case of the formation of the benzo[c]thiophene 21a, the
commercially available NaHS was hydrate. Thus, this cyclization
reaction requires the addition of a proton source, such as water or
ethanol. When we performed the reaction of compound 10 with
NaHTe13 under similar conditions, this reaction also directly led to
the benzo[c]tellurophenes 21c in 81% yield. In these cases, neither
the 6-endo, 6-endo mode 22 nor 5-exo, 6-endo mode compound 23
was obtained. Thus, the benzo[c]chalcogenophene derivatives
containing two chalcogenophene rings linked by a 1,4-distyryl
moiety were conveniently obtained.
HM
HM
Br
NaHM
NaHM
Br
MH
Br
24
13
25
5-exo, 5-exo
path b
6-endo, 6-endo
M
M
path a
Te
26
M
M
Te
28c (
a M = S (66%)
b M = Se (61%)
M
27b
M = Se (70%)
82%)
M
29
Scheme 4.

5152
H. Sashida et al. / Tetrahedron 66 (2010) 5149e5157
In all cases of the reaction of 19 with NaHS, NaHSe or NaHTe, the
6-endo and 5- exo-mode cyclizations did not proceed to give the
corresponding products 39.
Br
HM
NaHM
2.3. Structure of 5-exo and 6-endo mode cyclization products
Br
MH
30
16
All the obtained compounds are new except for trans-biiso-
thiophene 34a were mainly characterized on the basis of the
spectral analyses. The trans-3,30-bibenzo[c]thienylidene 34a was
already synthesized by the NaBH4 reduction of the trans-3,30-
bibenzo[c]thienylidene-1,10-dione.15 The structure of 37 and
regiochemistry of 34c were finally determined by X-ray single
crystallography. Figures 1 and 2 show the structures of 34c and 37,
respectively. Tables 1 and 2 list the selected interatomic distances,
angles, and torsional angles of 34c and 37.
5-exo, 5-exo
5-exo
M
CH3
31
a M = S (73%)
b M = Se (89%)
c M =Te (15%)
M
Te
32
(83%)
Scheme 5.
the selenium derivative 31b.14 A convenient preparation of the
bimethylidenebenzo[c]chalcogenophenes, directly linked to the 2,20
positions by a single carbonecarbon bond, was achieved.
Finally, the cyclization reactions of the dibenzyl chalcogenols 33
having one triple bond were examined. The bromide 19 was simi-
larly treated with NaHS hydrate to afford the trans-biisobenzo[c]
thiophene 34a in 80% yield without any characterized products.
Compound 34a will be produced by the dehydrogenation of the
essential cyclization product 35a, which is generated by the tandem
5-exo mode cyclization of the benzyl thiol intermediate 33a into the
triple bond with excellent regio- and stereoselectivity. The treat-
ment of 19 with freshly prepared NaHSe, and then the addition of
ethanol gave the 5-exo mode trans-biisobenzo[c]selenophene 34b
in 91% yield as the sole product. In contrast, the reaction of the
dibenzyl bromide 19 with NaHTe followed by the addition of eth-
anol resulted in both the tandem 5-exo and 6-endo mode ring
closures to yield the trans-biisobenzo[c]tellurophene 34c and the
5,11-dihydrotellurachrysene 37 in 46 and 48% yields, respectively.
The pure trans-34a and 37 could be isolated by fractional re-
crystallization from CHCl3. The formation of the tellurachrysene 37
would also be accomplised by the dehydrogenation from the es-
sential 6-endo mode cyclization product 38. The formation of trans-
34 by the dehydrogenation of 35 is more favored than that of cis-36
due to the steric hindrance between the two inner peri hydrogens
of the benzene rings. In these reactions, neither the essential cy-
clization products 35, 38, 39 nor alternative dehydrogenated cis-
products 36 were obtained Scheme 6.
Figure 1. ORTEP drawing of 34c with atomic numbering scheme for selected atoms
(50% probability thermal level).
Br
M
HM
M
-H2
1) NaHM / DMF
2) EtOH
5-exo, 5-exo
M
M
Br
19
MH
a
: M = S
34 a M = S (80%)
b M = Se (91%)
c M = Te (46%)
35
b: M = Se
c: M = Te
33
6-endo, 5-exo
6-endo, 6-endo
7
6
5
8
9
Te
4
1
Te
M
H
H
3
2
-H2
10
Te
M
M
11
Te
M
12
37(48%)
39
38
36
Scheme 6.

H. Sashida et al. / Tetrahedron 66 (2010) 5149e5157
5153
the self-resolution of the two enantiomers of 37, which may be
caused by the axial chirality on the twisted central double bond,
where the sign of the chirality is Sa for the single crystal. The tel-
lurium-containing six-membered rings assume the twisted con-
formation of a two-fold axis of symmetry on the central double
bond with the axial chirality. For the crystallographic structure of
37, the tellurium-containing six-membered ring is a novel ring
system not only as isotellurochromene, but also as saturated iso-
tellurochroman skeletons. The bond lengths (CeTe, 2.141 and
2.168 Å) and angle (87.6ꢀ) around the tellurium are comparable to
those observed in the telluracyclohexane skeletons in which the
corresponding averaged bond length and angle are 2.157 Å and
89.3ꢀ, respectively.17
Both the 5-exo and 6-endo mode cyclizations are favored in
Baldwin’s rules,18 which may be helpful to expect the selectivity for
ring-forming by the closure of the acyclic precursors. However,
a heteroatom or anion, which attacks a tetrahedral, trigonal or di-
agonal carbon atom to make a new ring, must be the second pe-
riodic row one; i.e., C, N, O, etc. based on the rules. There are no
systematic studies on the selectivity and stereochemical nature of
the third period and behavior elements, especially the chalcogen
elements, toward a triple bond.
Three chalcogenols 33, the precursors for the intramolecular
cyclizations are symmetrical compounds, which have no localized
electrovalencies. Therefore, the ring-closure mode of 33 may be
controlled by the distances between the chalcogen elements and
the reactant sp. carbons in the triple bond. In order to explain the
significant differences in the cyclization mode of the essential in-
termediates dithiol 33a, diselenol 33b, and ditellurol 33c, the 3D-
structures of 33 have been calculated by a density functional theory
method (PCM/B3LYP/DZ, DZ¼Lanl2DZdp for S, Se, and Te; 6-31G
*
Figure 2. ORTEP drawing of 37 with atomic numbering scheme for selected atoms
(50% probability thermal level).
for C and H; PCM solvent¼ethenol) using the Gaussian 03 program.
Table 3 lists the distances between the chalcogen atoms (M1, M2) of
the benzyl chalcogenol moieties and the C1 or C2 sp. carbons in the
triple bond for the optimized structures of 33.
Table 1
Selected bond lengths (Å) and bond angles (deg) of 34c
Te1eC1
Te1eC4
C1eC2
C2eC3
C3eC4
C1eC5
C1eTe1eC4
C2eC1eTe1
C5eC1eC2
C1eC5eC6
2.130(3)
2.143(4)
1.475(5)
1.408(5)
1.385(6)
1.347(5)
83.4(1)
C2eC1eTe1
126.7(3)
126.5(3)
Te2eC5
Te2eC8
C5eC6
C6eC7
C7eC8
2.134(4)
2.146(6)
1.468(5)
1.407(6)
1.509(7)
Table 3
Distances (Å) of between chalcogen atoms and sp. carbons for 33aec
HM2
C1
C2
C5e Te2eC8
C6eC5eTe2
C5eC1eTe1
C1eC5eTe2
83.0(2)
108.4(3)
124.9(3)
124.6(3)
M1H
Compd.
M
M1eC1
M1eC2
M2eC1
M2eC2
33a
33b
33c
S
Se
Te
3.71
3.89
3.98
4.22
4.42
4.48
4.35
4.48
4.59
3.78
3.90
4.04
Table 2
Selected bond lengths (Å) and bond angles (deg) of 37
C1eC1
*
1.352(4)
2.168(2)
1.412(3)
87.55(8)
119.3(1)
122.0(2)
108.2(2)
C1eTe1
2.141(2)
1.490(3)
1.498(3)
125.2(2)
115.4(1)
120.0(2)
The S1/C1 and S1/C2 distances for the dithiol 33a are
3.71 and 4.22 Å, respectively. The S2/C2 and S2/C1 have al-
most similar values (3.78 and 4.35 Å). It is presumed that the
5-exo, 5-exo mode ring closure reaction is more favored than
the 6-endo, 6-endo mode one because the S1/C1 (S2/C2)
distance is much shorter than the S1/C2 (S2/C1) one. Thus,
the trans-biisobenzo[c]thiophene 34a was formed through the
dehydrogenation of the essential 5-exo, 5-exo mode cyclization
product 35a. No 6-endo mode heterocycles are detected in this
tandem cyclization of the dithiol 33a. The Se1/C1 distance of
3.89 Å is also clearly shorter than that of the Se1/C2 (4.42 Å)
for 33b. The distances to the C1 and C2 from the Se2 are
similar. Thus, the essentially similar results are also obtained in
this case. In the case of 33c, both of the Te1/C1 (Te2/C2) and
Te2/C1 (Te1/C2) distances were elongated compared with S
and Se analogues. Therefore, both tandem 5-exo and 6-endo
C4
C2
*
eTe1
eC3
C1eTe1eC4
C1
*
eC2
eC4
*
*
*
C3
*
C1eC1
*
eC2
*
C1
C3
C3
*
*
*
eC1eTe1
eC2 eC1
eC4eTe1
C2eC1eTe1
C2 eC3 eC4
*
*
*
*
Although the benzo[c]tellurophenylidene skeleton found in 34c
has never been reported, the benzo[c]telluropene derivatives have
been structurally characterized.16 The tellurium containing rings in
34c have envelope structures. The bond angle of CeTeeC (82.6ꢀ)
and the bond lengths of TeeC (2.130 and 2.143 Å) are normal within
the expected values for the neutral TeII compounds.
Compound 37 crystallies from toluene to yield single crystals. Its
X-ray structure was solved in chiral space group C2 resulting from

5154
H. Sashida et al. / Tetrahedron 66 (2010) 5149e5157
mode ring closure reactions proceeded to afford the corre-
sponding five- and six-membered tellurium heterocycles in the
ratio of 1:1, respectively. Although these cyclization reactions
are obviously multi steps and the exact mechanisms are still
unclear, the experimental fact that compounds 34a,b only are
obtained during the cyclization of 33a,b and both compounds
34c and 37 are produced from 33c in approximately equal
yields could be explained by the calculated values of the dis-
tances between the chalcogen atoms and the sp. carbons of the
triple bond of 33.
purified by silica gel chromatography using n-hexane/CH2Cl2 (10:1)
as eluent to give pure 10. Yield: 4.38 g (94%). Yellow needles, mp
164e166 ꢀC (from CH2Cl2/hexane). 1H NMR (500 MHz, CDCl3): 4.74
(4H, s, PhCH2ꢁ2), 7.29e7.36, 7.46, 7.56 (4H, m, 2H, dd, J¼7.2, 1.9 Hz,
2H, dd, J¼7.0, 2.0 Hz, PheH), 7.59 (4H, s, 1,4-disubstituted PheH).
13C NMR (125 MHz, CDCl3): 32.0 (t), 88.5 (s), 94.9 (s),123.0 (s),123.2
(s), 128.6 (d), 129.0 (d), 129.8 (d), 131.6 (d), 132.6 (d), 139.3 (s). EIMS:
m/z (relative intensity, %) 466, 464, 462 (Mþ, 50, 100, 50), 385, 383
(56, 55), 302 (80). HRMS m/z Mþ calcd for C24H1681Br2: 465.9584.
Found: 465.9569.
3. Conclusion
4.1.3. 1,6-Bis[2-(hydroxymethyl)phenyl]hexa-1,5-diyne 12. o-Iodo-
benzyl alcohol 7 (23.4 g, 100 mol) was treated with hexa-1,5-diyne
11 (50 mol, 50% in hexane solution) instead of 1,4-dieth-
ynylbenzene 8 and worked up as described for the preparation of 9
to give 12. Yield: 12.04 g (83%). Colorless prisms, mp 164e165 ꢀC
(from EtOH/benzene). IR (KBr): 3350 (OH). 1H NMR (500 MHz,
CD3OD): 2.78 (4H, s, C^CCH2ꢁ2), 4.77 (4H, s, PhCH2ꢁ2), 7.20, 7.31,
7.37, 7.47 (2H, ddd, J¼7.6, 7.5, 1.3 Hz, 2H, ddd, J¼7.7, 7.5, 1.4 Hz, 2H,
dd, J¼7.6, 1.4 Hz, 2H, dd, J¼7.7, 1.3 Hz, PheH). 13C NMR (125 MHz,
CD3OD): 20.7 (t), 63.5 (t), 80.0 (s), 94.3 (s), 122.7 (s), 127.6 (d), 128.0
(d), 129.1 (d), 133.0 (d), 144.3 (s). EIMS: m/z (relative intensity, %)
290 (Mþ, 3), 272 (86), 253 (60), 145 (72), 115 (100). HRMS m/z Mþ
calcd for C20H18O2: 290.1307. Found: 290.1301.
In conclusion, we have shown that the dibenzyl dibromides 10,
13, 16, 19 react with NaHM in DMF to give the corresponding
dichalcogenols 20, 25, 30, 33, which fundamentally produce the
bisbenzo[c]chalcogenophene or isochromene derivatives by either
the regioselective double 5-exo or 6-endo mode intramolecular
cyclization into a triple bond in almost good yields. These simple
ring closure reactions offer a convenient access to the symmetrical
five- or six-membered ring assembled heterocycles containing
a chalcogen element and also ditellurachrysene.
4. Experimental section
4.1. General
4.1.4. 1,6-Bis[2-(bromomethyl)phenyl]hexa-1,5-diyne 13. o-Benzyl
alcohol 12 (3.38 g, 10 mmol) was treated with PBr3 and worked up
as described for the preparation of 10 to give 13. Yield: 3.16 g (76%).
Colorless needles, mp 124e126 ꢀC (from CH2Cl2). 1H NMR
(500 MHz, CDCl3): 2.85 (4H, s, C^CCH2ꢁ2), 4.67 (4H, s, PhCH2ꢁ2),
7.22e7.32, 7.39, 7.43 (4H, m, 2H, dd, J¼7.6, 1.4 Hz, 2H, dd, J¼7.4,
1.5 Hz, PheH). 13C NMR (125 MHz, CDCl3): 20.0 (t), 32.2 (t), 78.9 (s),
94.3 (s), 123.5 (s), 128.3 (d), 128.4 (d), 130.0 (d), 132.5 (d), 139.2 (s).
EIMS: m/z (relative intensity, %) 418, 416, 414 (Mþ, 1, 3, 1), 335, 333
(9, 6), 256, 255 (37, 100), 128 (52). HRMS m/z Mþ calcd for
C20H1681Br2: 417.9582. Found: 417.9603.
Melting points were measured on a Yanagimoto micro melting
point hot stage apparatus and are uncorrected. IR spectra were
recorded on a Horiba FT-720 spectrophotometer. MS and HRMS
spectra were recorded on a JEOL JMS-DX300 instrument. 1H NMR
spectra were recorded on a PMX-60SI (60 MHz), JEOL EX-90A
(90 MHz), JEOL ECA-400 (400 MHz) or JEOL ECP-500 (500 MHz)
spectrometer using TMS as internal standard and J values are given
in hertz. 13C NMR spectra were measured on a JEOL ECA-400
(100 MHz) or JEOL ECP-500 (125 MHz) spectrometer.
4.1.1. 1,4-Bis[2-(hydroxymethyl)phenylethynyl]benzene 9. To a mix-
ture of 1,4-diethynylbenzene 810 (3.15 g, 25 mmol) and o-iodo-
benzyl alcohol 7 (11.7 g, 50 mmol) in benzene (100 mL) and
piperidine (50 mL) were added PdCl2(Ph3P)2 (260 mg, 0.37 mmol)
and CuI (145 mg, 0.76 mmol). The mixture was stirred at room
temperature under argon for 16 h. Cold water (100 mL) was added
to the mixture, and the resulting aqueous mixture was extracted
with benzene (100 mLꢁ3). The combined organic extract was
washed with water (150 mLꢁ3), 5% H2SO4 (100 mLꢁ3), satd
NaHCO3 (100 mLꢁ2) and brine (200 mLꢁ2), and then dried
(MgSO4). The benzene was removed in vacuo to give the crude 9.
Yield: 6.08 g (72%). Yellow prisms, mp 195e197 ꢀC (from acetone/
hexane). IR (KBr): 3352 (OH). 1H NMR (500 MHz, CD3OD): 4.86 (4H,
s, PhCH2ꢁ2), 7.29, 7.40, 7.51, 7.54e7.60 (2H, ddd, J¼7.7, 7.5, 1.4 Hz,
2H, ddd, J¼7.7, 7.6, 1.3 Hz, 2H, dd, J¼7.5, 1.4 Hz, 6H, m, PheH). 13C
NMR (125 MHz, CD3OD): 63.4 (t), 89.7 (s), 94.4 (s), 124.6 (s), 127.9
(s), 128.2 (d), 130.0 (d), 132.6 (d), 133.0 (d), 138.8 (d), 144.4 (s). EIMS:
m/z (relative intensity, %) 338 (Mþ, 100), 289 (22), 178 (18). HRMS
m/z Mþ calcd for C24H18O2: 338.1307. Found: 338.1306.
4.1.5. 1,4-Bis[2-(hydroxymethyl)phenyl]buta-1,3-diyne 15. To a stir-
red solution of Cu(OAc)2$H2O (16.0 g, 80 mmol) in pyridine
(150 mL) and MeOH (150 mL) was added at room temperature,
trimethylsilylethynylbenzyl alcohol 146 (8.16 g, 40 mmol). The re-
action mixture was heated for 2 h with stirring, the mixture was
quenched with a saturated NH4Cl solution (200 mL) and extracted
with CH2Cl2 (150 mLꢁ3). The organic extracts were washed with 5%
H2SO4 (100 mLꢁ2), satd NaHCO3 (100 mLꢁ2) and brine
(150 mLꢁ3), and then dried (MgSO4). After removal of the organic
solvent in vacuo, the residual oil was purified by silica gel chro-
matography using n-hexane/CH2Cl2 (10:1) as eluent to give pure 15.
Yield: 7.90 g (78%). Pale yellow prisms, mp 174e176 ꢀC (from EtOH).
Lit.19 mp 176 ꢀC.
4.1.6. 1,4-Bis[2-(bromomethyl)phenyl]buta-1,3-diyne 16. o-Benzyl
alcohol 15 (2.62 g, 10 mmol) was treated with PBr3 and worked up
as described for the preparation of 10 to give 16. Yield: 2.48 g (64%).
Colorless needles, mp 139e140 ꢀC (from CH2Cl2). 1H NMR
(500 MHz, CDCl3): 4.70 (4H, s, PhCH2ꢁ2), 7.30, 7.37, 7.46, 7.57 (2H,
ddd, J¼7.6, 7.5, 1.0 Hz, 2H, ddd, J¼7.7, 7.5, 1.2 Hz, 2H, dd, 7.6, 1.2 Hz,
2H, dd, J¼7.7, 1.0 Hz, PheH). 13C NMR (125 MHz, CDCl3): 31.3 (t),
79.0 (s), 80.0 (s), 121.5 (s), 128.5 (d), 129.8 (d), 130.0 (d), 133.7 (d),
140.7 (s). EIMS: m/z (relative intensity, %) 390, 388, 386 (Mþ, 20, 40,
20), 309, 307 (28, 28), 228, 226 (100, 85). HRMS m/z Mþ calcd for
C18H1281Br2: 389.9268. Found: 389.9276.
4.1.2. 1,4-Bis[2-(bromomethyl)phenylethynyl]benzene 10. To a stir-
red solution of benzyl alcohol 9 (3.38 g, 10 mol) and pyridine
(1.03 g, 13 mol) in dry CHCl3 (10 mL) at 0 ꢀC was slowly added PBr3
(2.98 g, 11 mol). The mixture was stirred at same conditions for
15 h, and then poured into ice-water. The resulting aqueous mix-
ture was extracted with CH2Cl2 (75 mLꢁ3). The combined organic
extract was washed with 5% H2SO4 (50 mLꢁ2), satd NaHCO3
(50 mLꢁ2) and brine (100 mLꢁ3), and then dried (MgSO4). After
removal of the organic solvent in vacuo, the residual oil was
4.1.7. 2-Ethynylbenzyl alcohol 17. To a stirred solution of trime-
thylsilylethynylbenzyl alcohol 146 (14.28 g, 70 mmol) in methanol
(70 mL) at room temperature was added K2CO3 (700 mg). After the

H. Sashida et al. / Tetrahedron 66 (2010) 5149e5157
5155
reaction mixture had been stirred for 1 h, it was poured into ice-
water. The resulting aqueous mixture was extracted with CH2Cl2
(100 mLꢁ3), and the combined organic extract was washed with
brine (100 mLꢁ3), and then dried (MgSO4). The organic solvent was
evaporated in vacuo to give almost pure 17. Yield: 8.59 g (93%).
Colorless prisms, mp 62e64 ꢀC (from EtOAc/n-hexane). Lit.,20 mp
61e62 ꢀC.
CH2CH2), 3.85 (4H, s, PhCH2Sꢁ2), 6.59 (2H, s, olefiniceHꢁ2),
6.97e7.27 (8H, m, PheH). 13C NMR (100 MHz, CDCl3): 31.6 (t), 37.0
(t), 122.3 (d), 124.1 (d), 126.4 (d), 127.1 (s), 127.5 (d), 134.0 (s), 138.4
(s). EIMS: m/z (relative intensity, %) 322 (Mþ, 86), 161 (100), 160
(83), 128 (44). HRMS m/z Mþ calcd for C20H18S2: 322.0850. Found:
322.0853.
4.2.5. Dibenzo[d,l]-1,2-diselenacyclotetradeca-6,10-diyne
27b.
4.1.8. 1,2-Bis[2-(hydroxymethyl)phenyl]ethyne 18. o-Iodobenzyl al-
cohol 7 (14.04 g, 60 mmol) was treated with o-ethynylbenzyl al-
cohol 17 (7.92 g, 60 mmol) instead of hexa-1,5-diyne 2 and worked
up as described for the preparation of 9 to give 18. Yield: 12.00 g
(84%), colorless prisms, mp 130e133 ꢀC (from EtOH/EtOAc). Lit.,21
mp 122e125 ꢀC.
Yield: 291 mg (70%). Yellow prisms, mp 130e134 ꢀC (from CH2Cl2/
hexane). IR (KBr): 2229 (C^C). 1H NMR (400 MHz, CDCl3): 2.78 (4H,
s, C^CCH2CH2C^C), 4.51 (4H, s, PhCH2Seꢁ2), 7.15, 7.23, 7.33, 7.38
(2H, ddd, J¼7.6, 7.4, 1.3 Hz, 2H, ddd, J¼7.7, 7.4, 1.5 Hz, 2H, dd, J¼7.7,
1.3 Hz, 2H, dd, J¼7.7, 1.5 Hz, PheH). 13C NMR (100 MHz, CDCl3): 19.9
(t), 31.5 (t), 80.2 (s), 92.5 (s), 123.0 (s), 126.7 (d), 128.3 (d), 129.7 (d),
131.9 (d),141.3 (s). EIMS: m/z (relative intensity, %) 416 (Mþ, 90), 414
(82), 255 (78), 254 (73), 253 (100), 241 (57), 240 (53), 239 (75), 128
(95). HRMS m/z Mþ calcd for C20H1680Se2: 415.9586. Found:
415.9574. Anal. Calcd for C20H16Se2: C, 57.99; H, 3.89. Found: C,
56.57; H, 3.98.
4.1.9. 1,2-Bis[2-(bromomethyl)phenyl]ethyne 19. o-Benzyl alcohol
18 (2.38 g, 10 mmol) was treated with PBr3 and worked up as de-
scribed for the preparation of 10 to give 19. Yield: 2.11 g (58%).
Colorless needles, mp 122e124 ꢀC (from CH2Cl2/hexane). Lit.,22 mp
127e128 ꢀC.
4.2.6. Dibenzo[c,k]telluracyclotrideca-5,9-diyne 28c. Yield: 317 mg
(82%). Yellow prisms, mp 134e136 ꢀC (from CH2Cl2/hexane). IR
(KBr): 2225 (C^C). 1H NMR (500 MHz, CDCl3): 2.81 (4H, s,
C^CCH2CH2C^C), 4.51 (4H, s, PhCH2Teꢁ2), 7.06, 7.16, 7.23, 7.34
(2H, ddd, J¼7.7, 7.5, 1.4 Hz, 2H, ddd, J¼7.7, 7.5, 1.4 Hz, 2H, dd, J¼7.7,
1.4 Hz, 2H, dd, J¼7.7, 1.4 Hz, PheH). 13C NMR (125 MHz, CDCl3): 6.3
(t), 20.0 (t), 80.6 (s), 93.8 (s), 122.1 (s), 125.8 (d), 128.2 (d), 128.4 (d),
131.9 (d), 143.0 (s). EIMS: m/z (relative intensity, %) 386 (Mþ, 63),
384 (58), 256 (60), 255 (100), 241 (72), 239 (58), 128 (90). HRMS m/
z Mþ calcd for C20H16130Te: 386.0315. Found: 386.0314. Anal. Calcd
for C20H16Te: C, 62.57; H, 4.20. Found: C, 62.93; H, 4.37.
4.2. General procedure for the reaction of dibenzyl dibromide
10, 13, 16, 19 with NaHM
A solution of dibenzyl dibromide (1 mmol) in DMF (2 mL) was
slowly added to a solution of NaHS hydrate (70%, 2.4 mmol) in DMF
(5 mL) at 0 ꢀC under argon atmosphere. The reaction mixture was
stirred at room temperature for 12 h. In the case of NaHSe and NaHTe,
EtOH (1 mL) was added, and the reaction mixture was stirred for 1 h.
After addition of water (30 mL), the aqueous mixture was extracted
with benzene (50 mLꢁ3). The organic extract was washed with water
(30 mLꢁ3), brine (30 mLꢁ3), dried (MgSO4), and concentrated in
vacuo. Theresultingresiduewaspurifiedbysilicagelchromatography
using n-hexane/CH2Cl2 (30:1) as eluent to give pure product.
4.2.7. (Z,Z)-3H,30H-1,10-Bis(benzo[c]thiophenylidene)ethane
31a.
Yield: 215 mg (73%). Brown prisms, mp 171e173 ꢀC (from CH2Cl2).
1H NMR (400 MHz, CDCl3): 4.47 (4H, s, PhCH2Seꢁ2), 6.81 (2H, s,
olefiniceHꢁ2), 7.24e7.33, 7.68 (6H, m, 2H, d, J¼7.7 Hz, PheH). 13C
NMR (100 MHz, CDCl3): 37.5 (t), 112.5 (d), 120.9 (d), 125.3 (d), 127.3
(d), 127.9 (d), 139.3 (s), 141.3 (s), 142.1 (s). EIMS: m/z (relative in-
tensity, %) 294 (Mþ,100), 259 (18). HRMS m/z Mþ calcd for C18H14S2:
294.0537. Found: 294.0538.
4.2.1. (Z,Z)-1,4-Bis(benzo[c]thiophene-1-methylidenyl)benzene 21a.
Yield: 296 mg (80%). Reddish brown prisms, mp 195e197 ꢀC,
decomp., (from CH2Cl2). 1H NMR (500 MHz, CDCl3): 4.53 (4H, s,
PhCH2Sꢁ2), 7.14 (2H, s, olefiniceH), 7.29e7.40, 7.66, 7.75 (6H, m, 4H, s,
2H, d, J¼7.8 Hz, PheH). 13C NMR (125 MHz, CDCl3): 38.3 (t), 114.9 (d),
120.8 (d), 125.3 (d), 127.3 (d), 128.1 (d), 128.4 (d), 135.2 (s), 140.3 (s),
140.4 (s),140.8 (s). EIMS: m/z (relative intensity, %) 370 (Mþ,100), 337
(10). HRMS m/z Mþ calcd for C24H18S2: 370.0850. Found: 370.0851.
4.2.8. (Z,Z)-3H,30H-1,10-Bis(benzo[c]selenophenylidene)ethane 31b.
Yield: 347 mg (89%). Red prisms, mp 213e216 ꢀC (from CH2Cl2). 1H
NMR (500 MHz, CDCl3): 4.51 (4H, s, PhCH2Seꢁ2), 6.97 (2H, s,
olefiniceHꢁ2), 7.21e7.25, 7.28e7.33, 7.70 (3H, m, 3H, m, 2H, d,
J¼7.0 Hz, PheH). 13C NMR (125 MHz, CDCl3): 30.3 (t),118.2 (d),121.5
(d), 126.6 (d), 127.0 (d), 127.9 (d), 141.2 (s), 141.7 (s), 142.6 (s). EIMS:
m/z (relative intensity, %) 390 (Mþ, 96), 388 (86), 229 (97), 228
(100). HRMS m/z Mþ calcd for C18H1480Se2: 389.9426. Found:
389.9427.
4.2.2. (Z,Z)-1,4-Bis(benzo[c]selenophene-1-methylidenyl)benzene
21b. Yield: 410 mg (88%). Reddish brown prisms, mp 215e216 ꢀC
(from CHCl3). 1H NMR (500 MHz, CDCl3): 4.53 (4H, s, PhCH2Seꢁ2),
7.26e7.33, 7.36, 7.59, 7.78 (4H, m, 2H, d, J¼5.7 Hz, 4H, s, 2H, d,
J¼7.3 Hz, PheH), 7.52 (2H, s, olefiniceH). 13C NMR (125 MHz,
CDCl3): 30.9 (t), 119.4 (d), 121.3 (d), 126.6 (d), 127.0 (d), 128.0 (d),
128.1 (d), 136.2 (s), 138.7 (s), 141.6 (s), 142.3 (s). EIMS: m/z (relative
intensity, %) 466 (Mþ, 100), 464 (90), 462 (53). HRMS m/z Mþ calcd
for C24H1880Se2: 465.9744. Found: 465.9743.
4.2.9. (Z,Z)-3H,30H-1,10-Bis(benzo[c]tellurophenylidene)ethane 31c.
Yield: 73 mg (15%). Red prisms, mp 136e138 ꢀC (from CHCl3/hex-
ane). 1H NMR (400 MHz, CDCl3): 4.47 (4H, s, PhCH2Teꢁ2), 7.00 (2H,
s, olefiniceHꢁ2), 7.17e7.18, 7.19e7.21, 7.73 (4H, m, 2H, m, 2H, d,
J¼7.9 Hz, PheH). 13C NMR (100 MHz, CDCl3): 11.7 (t), 122.2 (d),
126.8 (d), 128.1 (d), 128.6 (d), 129.0 (d), 131.4 (s), 144.7 (s), 145.4 (s).
EIMS: m/z (relative intensity, %) 490, 488, 486 (Mþ, 40, 73, 78), 360
(45), 229 (99), 228 (100). HRMS m/z Mþ calcd for C18H14130Te2:
489.9222. Found: 489.9229.
4.2.3. (Z,Z)-1,4-Bis(benzo[c]tellurophene-1-methylidenyl)benzene
21c. Yield: 410 mg (81%). Yellow prisms, mp 193e195 ꢀC (from
CHCl3/hexane). 1H NMR (500 MHz, CDCl3): 4.70 (4H, s,
PhCH2Teꢁ2), 7.15e7.24, 7.26, 7.45, 7.80e7.89 (4H, m, 2H, s, 4H, s, 4H,
m, olefinic- and PheH). 13C NMR (125 MHz, CDCl3): 11.9 (t), 122.2
(d), 126.4 (s), 126.8 (d), 127.5 (d), 127.6 (d), 128.0 (d), 128.5 (d), 138.4
(s), 143.7 (s), 146.5 (s). EIMS: m/z (relative intensity, %) 566, 564,
562, 560 (Mþ, 37, 70, 75, 51), 306 (100). HRMS m/z Mþ calcd for
C24H18130Te2: 566.9536. Found: 566.9639.
4.2.10. (Z)-1-(3-o-Tolylprop-2-nylidene)-1,3-dihydrobenzo[c]-tellur-
ophene 32. Yield: 299 mg (83%). Yellow oil. IR (neat) cmꢂ1: 2181
(C^C). 1H NMR (400 MHz, CDCl3): 2.43 (3H, s, Me), 4.03 (2H, s,
PhCH2Te), 7.11e7.28 (8H, m, PheH), 7.37 (1H, s, olefiniceH). 13C
NMR (100 MHz, CDCl3): 6.1 (t), 21.4 (q), 113.9 (s), 125.9 (d), 127.1 (d),
4.2.4. 1,2-Bis(1H-isothiochromen-3-yl)ethane 26a. Yield: 251 mg
(66%). Reddish brown oil. 1H NMR (400 MHz, CDCl3): 2.68 (4H, s,

5156
H. Sashida et al. / Tetrahedron 66 (2010) 5149e5157
127.7 (d), 127.8 (d), 128.0 (d), 130.2 (d), 130.7 (d), 131.7 (s), 132.2 (d),
134.9 (s), 139.2 (s), 139.8 (s), 140.1 (s), 143.6 (d), 146.4 (s). EIMS: m/z
(relative intensity, %) 360, 358, 356 (Mþ, 47, 43, 37), 229 (100), 228
(95). HRMS m/z Mþ calcd for C18H14130Te: 360.0159. Found:
360.0162.
monochromated Mo
K
a
radiation source
(
l
¼0.71073 Å). The
structures were solved by direct methods (SHELXS-97),23 and re-
fined by full-matrix least-square methods on F2 for all reflections
(SHELXL-97)24 with all non-hydrogen atoms anisotropic and all
hydrogen atoms isotropic.
For 34c, the structure analysis is based on 2822 observed re-
flections with I>2.00 s(I) and 163 variable parameters; colorless
4.2.11. trans-3H,30H-1,10-Bi(benzo[c]thiophenylidene)
34a. Yield:
214 mg (80%). Yellow prisms (from CH2Cl2/n-hexane), mp
136e138 ꢀC. 15 (Lit.,15 mp 138e140 ꢀC. This compound was iden-
tical with the authentic sample. 1H NMR (500 MHz, CDCl3): 4.53
(4H, s, PhCH2Sꢁ2), 7.27, 7.35e7.43, 8.24 (2H, dd, J¼7.2, 7.0 Hz, 4H,
m, 2H, d, J¼8.1 Hz, PheH). 13C NMR (125 MHz, CDCl3): 38.1 (t), 125.1
(d), 125.3 (d), 127.0 (d, two carbons), 127.5 (s), 140.5 (s), 141.7 (s).
EIMS: m/z (relative intensity, %) 268 (Mþ, 100), 235 (42).
prisms, 196 K, monoclinic, space group P21/c, a¼8.8295(6) Å,
b¼11.1127(8) Å, c¼14.2605(10) Å,
b
¼92.925(1)ꢀ, V¼1397.41(17) Å3,
Z¼4, R¼0.0290, Rw¼0.0701, GOF¼1.067.
For 37, the structure analysis is based on 1520 observed re-
flections with I>2.00
s(I) and 83 variable parameters; colorless
prisms, 196 K, triclinic, space group C2, a¼17.287(2) Å, b¼4.5844
(6) Å, c¼8.6728(11) Å,
b
¼91.121(1)ꢀ, V¼687.18(15) Å3, Z¼2,
R¼0.0116, Rw¼0.0308, Flack Param¼0.04(2), GOF¼1.081.
CCDC-726522 for 34c and CCDC-726523 for 37 contain the
supplementary crystallographic data for this paper. These data can
be obtained free of charge from the Cambridge Crystallographic
Data Centre via www.ccdc.cam.ac.uk/data request/cif.
4.2.12. trans-3H,30H-1,10-Bi(benzo[c]selenophenylidene) 34b. Yield:
331 mg (91%). Yellow prisms (from CH2Cl2/n-hexane), mp
126e127 ꢀC. 1H NMR (500 MHz) 4.48 (4H, s, PhCH2Seꢁ2), 7.23
(2H, dd, J¼7.5, 7.2 Hz), 7.33 (2H, dd, J¼7.3, 7.2 Hz), 7.34 (2H, d,
J¼7.3 Hz), 7.81 (2H, d, J¼7.5 Hz). 13C NMR (125 MHz) 30.7 (t), 124.7
(d), 126.2 (s), 126.5 (d), 126.6 (d), 127.3 (d), 143.0 (s), 143.4 (s).
EIMS: m/z (relative intensity, %) 364, 362 (Mþ, 100, 90), 283 (30),
202 (97). HRMS m/z Mþ calcd for C16H1280Se2: 363.9272. Found:
363.9269.
Acknowledgements
A part of this work was supported by a Grant-in-Aid for Scien-
tific Research from The Ministry of Education, Culture, Sports, Sci-
ence and Technology of Japan (No. 19590022). The authors wish to
thank to Miss Michiko Maki, Miss Hiromi Yoshimoto, and Mr. Hir-
okazu Kodama (Hokuriku University) for their technical
assistances.
4.2.13. trans-3H,30H-1,10-Bi(benzo[c]tellurophenylidene) 34c. Yield:
211 mg (46%). Red prisms (from CHCl3), mp 177e179 ꢀC (dec). 1H
NMR (500 MHz) 4.73 (4H, s, PhCH2Teꢁ2ꢁ2), 7.17e7.25, and 7.34
(6H, m and 2H, d, J¼6.6 Hz, PheH). 13C NMR (125 MHz) 11.9 (t),
118.2 (s), 123.0 (d), 126.6 (d), 128.2 (d), 128.3 (d), 145.2 (s), 150.7 (s).
EIMS m/z (relative intensity): 464, 462, 460, 458 (Mþ, 18, 35, 37, 25),
203 (100). HRMS m/z Mþ calcd for C16H12130Te2: 463.9065. Found:
463.9022.
Supplementary data
Supplementary data associated with this article (calculated 3D-
structures of the chalcogenols 33, and the ORTEP drawing and,
X-ray data of 31b) can be found in the online version. Supple-
mentary data associated with this article can be found in online
version at doi:10.1016/j.tet.2010.04.101. These data include MOL
files and InChiKeys of the most important compounds described in
this article.
4.2.14. 6,12-Dihydro-5,11-ditellurachrysene 37. Yield: 221 mg (48%).
Yellow needles (from CHCl3), mp 192e194 ꢀC (dec). 1H NMR
(500 MHz) 3.98 (4H, s, 6- and 12-H2), PheH [7.13 (2H, ddd, J¼7.8,
7.3, 1.4 Hz), 7.21 (2H, ddd, J¼7.6, 7.3, 1.2 Hz), 7.27 (2H, dd, J¼7.6,
1.4 Hz), 7.30 (2H, dd, J¼7.8, 1.2 Hz)]. 13C NMR (125 MHz) 8.04 (t),
126.18 (d), 127.34 (d), 128.32 (d), 128.41 (d), 133.10 (s), 144.64 (s).
EIMS m/z (relative intensity): 464, 462, 460, 458 (Mþ,15, 26, 30, 20),
203(100). HRMS m/z Mþ calcd for C16H12130Te2: 463.9065. Found:
463.9091.
References and notes
1. Studies on tellurium-containing heterocycles. Part 30. Part 29: Sashida, H.; K.;
Kaname, Ohyanagi, M. Heterocycles, in press, doi:10.3987/COM-10-S(E)15.
2. (a) Zhang, J. X.; Dubois, P.; Jérôme, R. J. Chem. Soc., Perkin Trans. 2 1997,
1209e1216; (b) Wu, X.; Wu, J.; Liu, Y.; Jen, A. K.-Y. J. Am. Chem. Soc. 1999, 121,
472e473.
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4.2.15. 1,2-Bis(1H-isoselenochromen-3-yl)ethane 26b. A solution of
dibenzyl dibromide (1 mmol) in DMF (2 mL) was slowly added to
a solution of freshly prepared NaHSe (2 mmol)13 in DMF (5 mL) at
0 ꢀC under argon atmosphere. The reaction mixture was stirred at
room temperature for 1 h. After addition of EtOH (1 mL), the
mixture was heated at 110e115 ꢀC for 20 h and worked up as
described for the preparation of 21a to give 26b. Yield: 255 mg
(61%). Yellow prisms, mp 155e156 ꢀC (from CHCl3/hexane). 1H
NMR (400 MHz, CDCl3): 2.79 (4H, s, CH2CH2), 3.83 (4H, s,
PhCH2Seꢁ2), 6.72 (2H, s, olefiniceHꢁ2), 7.10e7.24 (8H, m, PheH).
13C NMR (100 MHz, CDCl3): 24.3 (t), 39.0 (t), 125.1 (d), 126.7 (d),
127.4 (d), 127.59 (d), 127.63 (d), 128.2 (s), 135.2 (s), 136.4 (s). EIMS:
m/z (relative intensity, %) 418 (Mþ, 65), 416 (47), 209 (85), 207
(44), 128 (100). HRMS m/z Mþ calcd for C20H1880Se2: 417.9739.
Found: 417.9741.
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4.3. X-ray structure determination
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ꢀ
ꢀ
17. Data of averaged bond length and angle were calculated based on the neutral
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