Studies on chalcogen-containing heterocycles. Part 37: M-CPBA oxidation of isotellurochromenes and isoselenochromenes

Article abstract of DOI:10.1016/j.tet.2012.07.023

The oxidation of the 1-unsubstituted isotellurochromenes and isoselenochromenes with m-CPBA resulted in a novel ring-opening reaction to give the o-formyl distyryl ditellurides and diselenides as the sole products in good yields, respectively. The o-benzoyl distyryl ditelluride and diselenide were also produced from the corresponding 1-phenylisochromenes. In contrast, the 1-benzyl and 1-n-butylisochromenes were oxidized to afford the (Z)-1-benzylideneisochromenes and (Z)-1-butylideneisochromenes under similar conditions; no distyryl compounds were obtained. The distyryl compounds were also obtained by the hydrolysis of the corresponding 2-benzochalcogenopyrylium salts, which were easily converted from the 2-benzoisochromenes by treatment with triphenylcarbenium tetrafluoroborate (Ph₃C+BF₄-).

Full text of DOI:10.1016/j.tet.2012.07.023

Tetrahedron 68 (2012) 10502e10509
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Studies on chalcogen-containing heterocycles. Part 37: m-CPBA oxidation
of isotellurochromenes and isoselenochromenesq
,
a
b
c
Haruki Sashida a , Mamoru Kaname , Kazuo Ohyanagi , Mao Minoura
*
a Faculty of Pharmaceutical Sciences, Hokuriku University, Kanagawa-machi, Kanazawa, Ishikawa 920-1181, Japan
b Faculty of Pharmacy, Institute of Medical, Pharmaceutical and Health Sciences, Kanazawa University, Kakuma-machi, Kanazawa 920-1192, Japan
c 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 oxidation of the 1-unsubstituted isotellurochromenes and isoselenochromenes with m-CPBA
resulted in a novel ring-opening reaction to give the o-formyl distyryl ditellurides and diselenides as
the sole products in good yields, respectively. The o-benzoyl distyryl ditelluride and diselenide
were also produced from the corresponding 1-phenylisochromenes. In contrast, the 1-benzyl and 1-n-
butylisochromenes were oxidized to afford the (Z)-1-benzylideneisochromenes and (Z)-1-
butylideneisochromenes under similar conditions; no distyryl compounds were obtained. The distyryl
compounds were also obtained by the hydrolysis of the corresponding 2-benzochalcogenopyrylium salts,
which were easily converted from the 2-benzoisochromenes by treatment with triphenylcarbenium
tetrafluoroborate ðPh3CþBF4ꢀÞ.
Received 22 May 2012
Received in revised form 3 July 2012
Accepted 9 July 2012
Available online 15 July 2012
Keywords:
Isotellurochromene
Isoselenochromene
m-CPBA
Distyryl ditelluride
Distyryl diselenide
Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction
several reports concerning the oxidation of the mono and benzene
ring fused six-membered heterocycles containing a chalcogen atom
The breakthrough of the synthesis, structure, physical properties,
and reactions of the heterocycles containing of chalcogen (sulfur,
selenium and tellurium) elements has lately been attracted in-
creasing interest in both the fields of heterocyclic1 and organo-
sulfur, -selenium, and -tellurium chemistry,2 but more in-
vestigations remain. We have studied the syntheses and reactions of
the novel tellurium- and selenium-containing heterocyclic com-
pounds3 over the past 20 years. Our synthetic strategy4 for the
preparation of these compounds is based on the intramolecular
cyclization of the tellurol or selenol moieties and related compounds
to a triple bond. As part of our continuing studies, we have pre-
viously focused on the synthesis of the isotellurochromenes5a and
isoselenochromenes5b as the precursors for the preparation of the
corresponding novel 2-benzopyrylium salts.6 In addition, several
reactivities of these isochromenes have been investigated: (1) the
transformation of the isotellurochromenes into the 1,2-dihydro-2-
metalanaphthalenes via a telluriumelithium exchange reaction;7
(2) the alkylation (phenylation) and halogenations;3b (3) the oxi-
dation of the isotellurochromenes.8
(Scheme 1). The selenium dioxide oxidation of 4H-thiopyrans and
4H-selenopyrans undergoes a ring contraction to give the 2-
aroylthiophenes and selenophenes, respectively (Eq. 1).10 The oxi-
dation of the 3,6-dihydro-2H-selenopyrans having an electron-
withdrawing group at the 2-position with sodium periodate is
also known to produce selenophenes (Eq. 2).11 Furthermore, the
oxidation of thiochromenes,12 selenochromenes,12 and tellur-
ochromenes13,14 with selenium dioxide, trityl perchlorate or K2CrO7
produced the corresponding 2-formylbenzo[b]-thiophenes, -sele-
nophenes, and -tellurophenes, respectively (Eq. 3). Whereas the
normal isothiochromene S-oxide15 is easily isolated as the ther-
mally stable m-CPBA oxidation products (Eq. 4), a similar oxidation
of the highly substituted isoselenochromenes16 gives the benzo[b]
selenophene derivatives as the main product (Eq. 5). These facts
prompted us to examine the oxidation of the simple iso-
tellurochromenes and isoselenochromenes. In this report, we de-
scribe the oxidative one-pot conversion of the isotellurochromenes
and isoselenochromenes to the corresponding distyryl dichalco-
genides and others as additional reactivities for these isochromenes
involving an X-ray crystallographic analysis of the oxidation
product.
The synthetic utility of the m-CPBA of acylic alkyl phenyl sele-
nides and tellurides has been reviewed by Uemura,9 and there are
Vinylic tellurides17 and selenides18 involving styryl compounds
have been widely studied and used in organic syntheses. Most of
the vinyl derivatives have been synthesized by the addition of the
q
Part 36: Ref. 3i.
* Corresponding author. E-mail address: h-sashida@hokuriku-u.ac.jp (H. Sashida).
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.tet.2012.07.023

H. Sashida et al. / Tetrahedron 68 (2012) 10502e10509
10503
Table 1
Ar
M
Ar
(Z)-Bis(o-formylstyryl) ditellurides 3A and diselenides 3B
SeO2
Eq. 110
R1
Product
Yielda (%)
Ar
Entry
M
COAr
M
Ar
Ar
R
M = S, Se
1
2
3
4
5
6
7
8
Te
Te
Te
Te
Te
Te
Te
Te
Se
Se
Se
Se
Se
Se
Se
t-Bu
H
Me
n-Pr
n-Bu
n-Oct
1-Cyclohexenyl
Ph
t-Bu
H
Me
n-Pr
n-Bu
n-Oct
1-Cyclohexenyl
3Aa
3Ab
3Ac
3Ad
3Ae
3Af
3Ag
3Ah
3Ba
3Bb
3Bc
3Bd
3Be
3Bf
83
43
57
60
70
62
83
78
88
77
55
61
76
65
73
Me
Me
Me
NaIO4
Eq. 211
Me
R
Se
Se
SeO2
9
Eq. 312-14
CHO
10
11
12
13
14
15
M
M
M = S, Se, Te
m-CPBA
m-CPBA
Eq. 415
S
S
3Bg
O
a
Isolated yield.
COOMe
COOMe
MeO
MeO
also produced the corresponding ditellurides 3Ab in 43% yield,
and the 3-alkyl 1Acef, 3-alkenyl 1Ag, and the 3-
phenylisotellurochromenes 1Ah were oxidized in moderate to
good yields to give the corresponding ditellurides 3Aceh via the
presumable telluroxide 2A (entries 2e8).
Eq. 516
Se
Ar
Se
Scheme 1.
Based on this isotellurochromene oxidation result, we have
become significantly interested in the similar m-CPBA oxidation of
selenium analogues, i.e., the isoselenochromenes 1B comparing the
highly substituted isoselenochromenes reported by Okuma.16
When the isoselenochromenes 1B bearing a primary, secondary
or tertiary alkyl group at the C-3 position and unsubstituted
derivatives were oxidized by m-CPBA under the same conditions,
the corresponding ring-opening bis(o-formylstyryl) diselenides
3Baeg were obtained in one-pot from 1B in yields ranging from
55% to 88% without any ring contraction products(entries 9e15).
The obtained results are quite similar to the m-CPBA oxidation of
the isotellurochromenes.
tellurols or selenols and related compounds to an acetylene. Thus,
the result described in this paper provides a new practical access
for the preparation of the vinylic tellurides and selenides.
2. Results and discussion
2.1. m-CPBA oxidation of 1-unsubstituted isotellurochromenes
and isoselenochromenes: formation of distyryl ditellurides and
diselenides
The oxidation of the 1-unsubstituted isotellurochromenes with
m-CPBA is shown in Scheme 2 and the results are summarized in
Table 1. When 1.2 equiv of m-CPBA was added to a solution of 3-
tert-butyl-1H-isotellurochromene 1Aa in CHCl3 at 0 ꢁC, the start-
ing material immediately disappeared; the reddish yellow solu-
tion turned colorless. The (Z)-bis(o-formylstyryl) ditelluride 3Aa
was isolated as red prisms in 83% yield as the sole product after
the usual workup. No telluroxide 2Aa was produced (Table 1,
entry 1). The MS spectrum of this compound suggested the
ditelluride molecular formula of C26H30O2Te2 with a molecular
ion at m/z¼634 (130Te) and the expected isotope pattern for Te2.
The HRMS of 3Aa also showed the same exact molecular formula.
The IR spectrum showed the characteristic absorption due to the
formyl carbonyl group at 1690 cmꢀ1. In the NMR spectrum, the
benzyl singlet 2H proton signals disappeared at ca. 3.8 ppm,
and the olefinic 1H proton remains at ca. 6.9 ppm. These spec-
troscopic data were consistent with the 3Aa structure. A similar
m-CPBA oxidation of the unsubstituted isotellurochromene 1Ab
2.2. m-CPBA oxidation of 1-methyl and 1-
phenylisotellurochromenes and isoselenochromenes
Next, a similar m-CPBA oxidation of the 1-substituted 3-tert-
butylisochromenes was carried out (Scheme 3). These compounds
are readily obtained from 3-tert-butyl-1H-isotellurochromene 1Aa
and -1H-isoselenochromene 1Ba, which are superior substrates in
stability and synthetic easiness via the corresponding 2-
benzopyrylium salts. 3-tert-Butyl-1-phenyl-1H-isotellurochromene
4A6c and -1H-isoselenochromene 4B6b were similarly oxidized to
produce the bis(o-benzoylstyryl) ditelluride 6A and diselenide 6B by
m-CPBA under the same conditions in 80% and 81% yields, re-
spectively. While the oxidation of 1-methylisotellurochromene 5A6c
with m-CPBA gave a complex mixture without the desired bis(o-
acetylstyryl) ditelluride 7A under the same conditions, the bis(o-
acetylstyryl) diselenide 7B was determined to form by the m-CPBA
oxidation of 1-methylisoselenochromene 5B6b in only 10% yield
along with many uncharacterized compounds.
R1
R1
m-CPBA
M
M
O
t-Bu
2
1
t-Bu
m-CPBA
M
a: R1 = t-Bu
b: R1 = H
A: M = Te
B: M = Se
2
M
C
O
R2
c: R1 = Me
A: M = Te
B: M = Se
R2
R1
d: R1 = n-Pr
e: R1 = n-Bu
f: R1 = n-Oct
g: R1 = cyclohexenyl
h: R1 = Ph
OHC
6A: M = Te, R2 = Ph (80%)
6B: M = Se, R2 = Ph (81%)
7A: M = Te, R2 = Me (0%)
7B: M = Se, R2 = Me (10%)
4: R2 = Ph
5: R2 = Me
M
M
R1
CHO
3
Scheme 2.
Scheme 3.

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H. Sashida et al. / Tetrahedron 68 (2012) 10502e10509
2.3. m-CPBA oxidation of 1-benzyl and 1-
butylisotellurochromenes and isoselenochromenes
the dichalcogenides (path a) and 1-methylideneisochromenes
(path b) from the 1-benzylisochromenes 8 and the 1-n-butyliso-
chromenes 9 having a methylene moiety at the C-1 position of the
isochromene ring including the 1-methyl derivatives 5. However,
the m-CPBA oxidation of 8 and 9 gave only methylene compounds
10 and 11, and no bis(o-acylstyryl) ditelluride and diselenide. For
the m-CPBA oxidation of the 1-methylisochromenes 5, the de-
hydration reaction of the intermediate 13 may mainly proceeded to
produce the exo-methylene compounds 15, which are probably too
unstable to isolate. Therefore, the products decomposed, and
a small amount of 7B was obtained from 5. All of the telluroxides
12A, selenoxides 12B, and 1-hydroxyisochromenes 13 could not be
isolated due to their unstabilities. Fortunately, the oxidation of the
tert-butyl derivative 1Aa with m-CPBA, followed by treatment with
Ac2O at room temperature resulted in a Pummerer rearrangement
to afford the expected 1-acetoxyisotellurochromene 16 together
with a small amount of the ditelluride 3Aa. The hydrolysis of the
isolated acetoxy derivative 16 with NaHCO3 aq gave the ditelluride
3Aa in almost quantitative yield. This finding on the m-CPBA oxi-
dation of the isochromenes suggests that the essential oxidative
products are clearly the 1-hydroxy derivatives 13. In the case of
only 1-substituted isochromenes 8 and 9 having at least a methy-
lene moiety, including the 1-methylisochromenes 5, the (Z)-
methylidene compounds 10 and 11 were produced by the de-
hydration of 13 (path b); the exo-methylene compounds 15 could
not be obtained because of their instability. When the
dehydration of 13 is impossible such as 1 and 4, the ring-opening
reaction mainly proceeded to give the dichalcogenides 3 and 6
through further oxidation of the chalcogenols 14, which are the
tautomers of 1-hydroxyisochromenes 13 (path a). Thus, path a is
predominant.
In contrast, when the 1-benzyl 86b and 1-n-butylisochromenes
9,6c which had a methylene moiety at the C-1 position of the iso-
chromene ring, were oxidized with m-CPBA, the (Z)-methylidene
compounds 10, 11 were produced in range of 58e65% yields as
shown in Scheme 4. The structures of the benzylidene derivatives
10A, B were identical to the authentic samples,5a,6b which were
reported in our previous paper. The butylidene compounds 11,
which were produced from the corresponding isochromenes 9,
were characterized by spectral comparison with 10.
t-Bu
t-Bu
m-CPBA
M
M
A: M = Te
B: M = Se
H2C
R3
R3
H
10A: M = Te, R3 = Ph (58%)
10B: M = Se, R3 = Ph (64%)
11A: M = Te, R3 = n-Pr (60%)
11B: M = Se, R3 = n-Pr (65%)
8: R3 = Ph
9: R3 = n-Pr
Scheme 4.
A plausible mechanism for the formation of both the benzoyl 6
and acetyl derivatives 7 from 4 and 5 may be similar to the formyl
derivatives 3 from the isochromenes 1 (Scheme 5). The essential
telluroxides 12A or selenoxides 12B generated by the oxidation of
the corresponding isochromenes 1, 4, 5, 8, and 9 rearranged to af-
ford the 1-hydroxyisochromenes 13 by a Pummerer-type rear-
rangement. The intermediate 13 undergoes ring-opening with
migration of the hydroxy proton to form the vinyltellurol 14A or
selenol 14B (path a). The resulting 14 may be oxidized by m-CPBA
or air to give the distyryl derivatives 3, 6, and 7. The 1-methylidene
compounds 10 and 11 would be formed by the dehydration of the
intermediate 13 (path b). In these cases, the corresponding distyryl
ditellurides and diselenides were not obtained. The significant
differences in the formation of products according to whether or
not the 1-substituent is a primary alkyl group could be clearly
explained; path b is suggested to be predominant because of the
following point. There are two possible paths for the formations of
2.4. Hydrolysis of 2-benzopyrylium salts
In addition, the ditellurides 3A and selenides 3B could be ob-
tained by the hydrolysis of the 2-benzotelluropyrylium 17A6a and 2-
benzoselenopyrylium tetrafluoroborates 17B6a in high yields, which
had previously been prepared by the treatment of the isochromenes
1
with triphenylcarbenium tetrafluoroborate ðPh3CþBF4ꢀÞ in
MeNO2 in highyields (Scheme 6). We have reported6bee the reaction
of the 2-benzotelluropyrylium and 2-benzoselenopyrylium salts
with several nucleophiles, such as hydrides, alkoxides, amines, and
an active methylene compound to afford the corresponding 1-
substituted isochromenes as the sole products in good to highyields.
R1
R1
R1
R1
m-CPBA
MH
[O]
M
2
M
M
R2
C
O
R2
C
O
O
R2
12
R2
3, 6, 7
1, 4, 5, 8, 9
14
R1 = t-Bu
A: M = Te
B: M = Se
R2 = H, Ph, Me
R2 = H
Ac2O
path a
R1
R1 = t-Bu
R1
H
t-Bu
t-Bu
R2 = CH2R3
NaHCO3 aq.
M
M
M
M
path b
R2
13
O
OAc
16
H
R3
10, 11
(unstable)
15
Scheme 5.

H. Sashida et al. / Tetrahedron 68 (2012) 10502e10509
10505
Scheme 6.
ꢀ
When the 3-tert-butyltelluropyrylium salt 17Aawas treated with
cold water, the (Z)-bis(o-formylstyryl) ditelluride 3Aa was isolated
in 92% yield. However, the hydrolysis of the 3-unsubstituted tel-
luropyrylium salt 17Ab produced the distyryl ditelluride 3Ab in only
24% yield. The 3-tert-butylselenopyrylium salt 17Ba was hydrolyzed
to give the 1-hydroxyisoselenochromene 18 and the diselenides
3Ba, which were isolated in 89% and 10% yields, respectively; the
former is probably the initial product, and was easily transformed to
give 3Ba in quantitative yield by storage for a few days on contact
with air or oxidation with an appropriate oxidizing reagent such as
m-CPBA. The initial 18 were produced by the nucleophilic attack of
water at the C-1 position of the pyrylium cation 17Ba, and then
oxidized to give 3Ba. Unfortunately, the treatment of the 3-
unsubstituted selenopyrylium salt 17Bb with H2O gave a complex
mixture without any products. Compounds 18 (13Ba) should be
produced by the oxidation of the isoselenochromene 1Ba with m-
CPBA under the above conditions, but not isolated.
of 3Aa (2.715(1) A) is close to the averaged value of the neutral
ꢀ
diorgano ditellurides (2.705 A), which was calculated based on the
reported structure in Cambridge Structural Database.19 The torsion
angle of CeTeeTeeC in 3Aa is 132.3ꢁ and has a transoid confor-
mation. Although the intramolecular TeeO or eN interactions have
been found in the organotellurium compounds containing oxygen
or nitrogen atom(s) in their functional group,20 no such significant
interaction around the tellurium is observed in 3Aa in which the
ꢀ
shortest TeeO distance is 4.860 A.
2.6. Chlorination of (Z)-bis(o-formylstyryl) ditelluride
Finally, the reactivities of the obtained ditellurides were exam-
ined. The tert-butyl ditelluride 3Aa was easily converted to the
tellurium trichloride 19 by means the fission of the TeeTe bond by
treatment of sulfuryl chloride. The treatment of 3Aa and 3Ac with
a small amount excess of sulfuryl chloride in CH2Cl2 at 0 ꢁC pro-
duced the trichlorides 19a and 19c in 95% and 84% yields, re-
spectively, as shown in Scheme 7.
2.5. Structure of (Z)-bis(o-formylstyryl) ditelluride
The geometry of the double bond in products 3, 6, and 7 was
proved to be (Z)-stereochemistry based on the vicinal coupling
constant (J¼10 Hz) in the 1H NMR spectra of the nonsubstituted
derivative 3Ab. The molecular structure of 3 was finally established
by an X-ray crystallographic analysis using the tert-butyl ditelluride
3Aa. The ORTEP drawing is shown in Fig. 1. The TeeTe bond length
Scheme 7.
3. Conclusion
In the present study, the m-CPBA oxidation of the iso-
tellurochoromenes and isoselenochromenes having substituents at
the C-1 and (or) C-3 position of the isochromene ring was exam-
ined. As a result, this novel ring-opening m-CPBA oxidation of the
isotellurochoromenes and isoselenochromenes has provided the
facile one-pot alternative preparation of the divinyl ditellurides and
selenides.
4. Experimental section
4.1. General
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 in CDCl3 and J values
are given in hertz. 13C NMR spectra were recorded on a JEOL ECA-
400 (100 Hz) or JEOL ECP-500 (125 Hz) spectrometer in CDCl3.
Fig. 1. An ORTEP drawing of 3Aa with thermal ellipsoid plot (50% probability).

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H. Sashida et al. / Tetrahedron 68 (2012) 10502e10509
77Se and 125Te NMR spectra were obtained on a Bruker AVANCE
II 600 (76.3, 189 MHz) spectrometer in CDCl3 with external
standards.
4.2.2. 2-Benzotelluropyrylium salts and 2-benzoselenopyrylium
salts. The starting 2-benzotelluropyrylium salts 17A and 2-
benzoselenopyrylium salts 17B were easily prepared in good
yields by the reported method.6a
4.2. Starting materials
4.3. Typical procedure for m-CPBA oxidation of 1H-iso-
tellurochromenes1A, 4A, 5A, 8A, 9Aand1H-isoselenochromenes
1B, 4B, 5B, 8B, 9B
4.2.1. Isotellurochromenes and isoselenochromenes. The starting
materials, 3-tert-butyl-1H-isotellurochromene 1Aa,6a 1H-iso-
tellurochromene 1Ab,6a 3-methyl-1H-isotellurochromene 1Ac,6a 3-
n-butyl-1H-isotellurochromene 1Ae,6a 3-phenyl-1H-isotellurochro
mene 1Ah,6a 3-tert-butyl-1-phenyl-1H-isotellurochromene 4A,6c 3-
tert-butyl-1-methyl-1H-isotellurochromene 5A,6c 1-benzyl-3-tert-
butyl-1H-isotellurochromene 8A,6b 1-n-butyl-3-tert-butyl-1H-iso-
tellurochromene 9A,6c 3-tert-butyl-1H-isoselenochromene 1Ba,6a
1H-isoselenochromene 1Bb,6a 3-methyl-1H-isoselenochromene
1Bc,6a 3-n-butyl-1H-isoselenochromene 1Be,6a 3-tert-butyl-1-
phenyl-1H-isoselenochromene 4B,6b 3-tert-butyl-1-methyl-1H-
isoselenochromene 5B,6b 1-benzyl-3-tert-butyl-1H-isoselenochr
omene 8B,6b and 1-n-butyl-3-tert-butyl-1H-isoselenochromene
9B6b were prepared by the literature method. 3-n-Propyl-1H-iso-
tellurochromene 1Ad, 3-n-octyl-1H-isotellurochromene 1Af, 3-
cyclohexenyl-1H-isotellurochromene 1Ag, 3-n-propyl-1H-isoselen
ochromene 1Bd, 3-n-octyl-1H-isoselenochromene 1Bf, and 3-
cyclohexenyl-1H-isoselenochromene 1Bg were also synthesized
according to the literature method.6
m-CPBA (70%, 296 mg, 1.2 mmol) was added to a solution of 3-
tert-butylisotellurochromene (1Aa, 302 mg, 1.0 mmol) in dry CHCl3
(10 mL) at 0 ꢁC and the mixture was stirred at room temperature for
1 h. After addition of satd NaHCO3 aq (10 mL), aqueous mixture was
extracted with CH2Cl2 (50 mLꢂ3). The organic layers were washed
with NH4Cl aq, brine (30 mLꢂ2), dried (MgSO4), and evaporated.
The resulting residue was chromatographed on silica gel using n-
hexane/CH2Cl2 (2:1) as an eluent to give pure ditelluride.
4.3.1. (Z)-Bis(a-tert-butyl-o-formylstyryl) ditelluride 3Aa. Yield:
263 mg (83%), dark red prisms, mp 140e143 ꢁC (from acetone/hex-
ane). IR (KBr, cmꢀ1): 1690 (C]O); 1H NMR (500 MHz): 1.24 (18H, s, t-
Buꢂ2), 6.88 (2H, s, PheCH]Ceꢂ2), 7.20, 7.36, 7.47, 7.80 (2H, d,
J¼7.6 Hz, 2H, dd, J¼7.7, 7.7 Hz, 2H, ddd, J¼7.7, 7.6, 1.4 Hz, 2H, dd, J¼7.7,
1.4 Hz, PheH), 10.06 (2H, s, CHOꢂ2); 13C NMR (125 MHz): 30.7 (q),
41.3(s) 127.5(d),128.3(d),131.6(d),133.5(s),133.6(d),134.6(d),138.0
(s),144.4 (s),191.5 (d); 125Te NMR (189 MHz): 275.8; MS m/z (relative
intensity, %): 634, 632, 630, 628 (Mþ,1, 2, 2,1),187 (100),145 (33),115
(22); HRMS m/z calcd for C26H30O1230Te2: 634.0370. Found: 634.0352.
4.2.1.1. 3-n-Propyl-1H-isotellurochromene 1Ad. Yield 63%, yel-
low oil. 1H NMR (90 MHz): 0.96, 1.3e1.7, 2.56 (3H, t, J¼7 Hz, 2H, m,
2H, t, J¼7 Hz, n-Pr), 3.88 (2H, s, 1-H2), 6.61 (1H, s, 4-H), 7.0e7.3 (4H,
m, PheH); MS m/z (relative intensity, %): 288 (Mþ, 75), 286 (70),129
(100); HRMS m/z: calcd for C12H14Te: 288.0158. Found: 288.0153.
4.3.2. (Z)-Bis(o-formylstyryl) ditelluride 3Ab. Yield: 112 mg (43%),
orange prisms, mp 95e97 ꢁC (from CH2Cl2/hexane). IR (KBr, cmꢀ1):
1694 (C]O); 1H NMR (500 MHz): 7.28 (2H, d, J¼10.3 Hz, PheCH]
Ceꢂ2), 7.92 (2H, d, J¼10.3 Hz, eCH]CHeTeꢂ2), 7.26, 7.44, 7.55,
7.86 (2H, d, J¼7.8 Hz, 2H, dd, J¼7.6, 7.4 Hz, 2H, ddd, J¼7.8, 7.4, 1.4 Hz,
2H, dd, J¼7.6, 1.4 Hz, PheH), 10.21 (2H, s, CHOꢂ2); 13C NMR
(125 MHz): 112.9 (d), 127.9 (d), 128.4 (d), 130.9 (d), 132.9 (s), 134.0
(d), 135.4 (d), 141.8 (s), 191.7 (d); MS m/z (relative intensity, %): 522,
520, 518, 516 (Mþ, 2, 3, 3, 2), 131 (100), 103 (22), 77 (14); HRMS m/z
calcd for C18H14O1230Te2:521.9118. Found: 521.9088.
4.2.1.2. 3-n-Octyl-1H-isotellurochromene 1Af. Yield 80%, yellow
oil. 1H NMR (90 MHz): 0.88, 1.1e1.6, 2.57 (3H, t, J¼7 Hz, 12H, m, 2H,
t, J¼7 Hz, n-Oct), 3.85 (2H, s, 1-H2), 6.59 (1H, s, 4-H), 7.1e7.2 (4H, m,
PheH); MS m/z (relative intensity, %): 358 (Mþ, 100), 356 (92), 129
(65); HRMS m/z: calcd for C17H24Te: 358.0941. Found: 358.0940.
4.2.1.3. 3-Cyclohexenyl-1H-isotellurochromene 1Ag. Yield 65%,
yellow oil. 1H NMR (90 MHz): 1.4e1.8, 2.0e2.6, 6.0 (4H, m, 4H, m,
1H, m, cyclohexenyleH), 3.77 (2H, s, 1-H2), 6.83 (1H, s, 4-H), 7.0e7.2
(4H, m, PheH); MS m/z (relative intensity, %): 326 (Mþ, 100), 324
(90), 196 (43), 167 (55); HRMS m/z: Mþ calcd for C15H16Te:
326.0315. Found: 326.0317.
4.3.3. (Z)-Bis(o-formyl-
a-methylstyryl)
ditelluride
3Ac. Yield:
156 mg (57%), orange oil. IR (neat, cmꢀ1): 1693 (C]O); 1H NMR
(500 MHz): 2.57 (6H, d, J¼1.6 Hz, Me), 7.02 (2H, d, J¼1.6 Hz, PheCH]
Ceꢂ2), 7.28, 7.47, 7.59, 7.91 (2H, dd, J¼7.6, 0.6 Hz, 2H, ddd, J¼7.8, 7.4,
0.6 Hz, 2H, ddd, J¼7.6, 7.4, 1.4 Hz, 2H, dd, J¼7.8, 1.4 Hz, PheH), 10.19
(2H, s, CHOꢂ2); 13C NMR (125 MHz): 32.2 (q), 117.0 (s), 128.4 (d),
129.3 (d), 130.3 (d), 131.8 (d), 133.8 (s), 134.0 (d), 143.3 (s), 191.7 (d);
MS m/z (relative intensity, %): 550, 548, 546, 544 (Mþ, 1, 2, 2, 1), 145
(100), 115 (35); HRMS m/z calcd for C20H18O1230Te2:549.9431. Found:
549.9440.
4.2.1.4. 3-n-Propyl-1H-isoselenochromene 1Bd. Yield 63%, yel-
low oil. 1H NMR (90 MHz): 0.97, 1.3e1.8, 2.46 (3H, t, J¼7 Hz, 2H, m,
2H, t, J¼7 Hz, n-Pr), 3.80 (2H, s, 1-H2), 6.57 (1H, s, 4-H), 7.0e7.5 (4H,
m, PheH); MS m/z (relative intensity, %): 238 (Mþ, 100), 236 (48),
209 (35), 128 (61); HRMS m/z: Mþ calcd for C12H14Se: 238.0261.
Found: 238.026.
4.3.4. (Z)-Bis(o-formyl-a-n-propylstyryl) ditelluride 3Ad. Yield:
4.2.1.5. 3-n-Octyl-1H-isoselenochromene 1Bf. Yield 60%, yellow
oil. 1H NMR (90 MHz): 0.88, 1.1e1.7, 2.48 (3H, t, J¼7 Hz, 12H, m, 2H,
t, J¼7 Hz, n-Oct), 3.83 (2H, s, 1-H2), 6.64 (1H, s, 4-H), 7.1e7.3 (4H, m,
PheH); MS m/z (relative intensity, %): 308 (Mþ, 100), 306 (50), 209
(36), 128 (50); HRMS m/z: Mþ calcd for C17H24Se: 308.1044. Found:
308.1045.
181 mg (60%), orange oil. IR (neat, cmꢀ1): 1691 (C]O); 1H NMR
(500 MHz): 0.94, 1.47e1.58, 2.62 (6H, t, J¼7.3 Hz, 4H, m, 4H, t,
J¼7.3 Hz, n-Pr), 6.97 (2H, s, PheCH]Ceꢂ2), 7.25, 7.46, 7.58, 7.90
(2H, d, J¼7.5 Hz, 2H, dd, J¼7.7, 7.5 Hz, 2H, ddd, J¼7.5, 7.5, 1.2 Hz, 2H,
dd, J¼7.7, 1.2 Hz, PheH), 10.19 (2H, s, CHOꢂ2); 13C NMR (125 MHz):
13.1 (q), 23.0 (t), 45.2 (t),124.1 (s),128.3 (d),129.1 (d),130.5 (d),131.4
(d),133.6 (s),133.9 (d),143.5 (s),191.5 (d); MS m/z (relative intensity,
%): 606, 604, 602, 600 (Mþ, 4, 7, 8, 5), 173 (100), 145 (10), 115 (14);
HRMS m/z calcd for C24H26O1230Te2: 606.0057. Found: 606.0057.
4.2.1.6. 3-Cyclohexenyl-1H-isoselenochromene 1Bg. Yield 68%,
yellow oil. 1H NMR (500 MHz): 1.61e1.67, 1.72e1.78, 2.22e2.28,
2.43e2.48, 3.80, 6.35 (2H, m, 2H, m, 2H, m, 2H, m, 3H, s, 1H, t,
J¼4.2 Hz, cyclohexenyleH, 2H, s, 1-H2), 6.91 (1H, s, 4-H), 7.12e7.21
(4H, m, PheH); MS m/z (relative intensity, %): 276 (Mþ, 100), 274
(55), 209 (40), 128 (60); HRMS m/z: Mþ calcd for C15H16Se:
276.0418. Found: 276.0413.
4.3.5. (Z)-Bis(
a-n-butyl-o-formylstyryl)
ditelluride
3Ae. Yield:
221 mg (70%), orange oil. IR (neat, cmꢀ1): 1695 (C]O); 1H NMR
(500 MHz): 0.92, 1.32e1.40, 1.47e1.54, 2.65 (3H, t, J¼7.3 Hz, 4H, m,
4H, m, 4H, t, J¼7.4 Hz, n-Bu), 6.97 (2H, s, PheCH]Ceꢂ2), 7.25, 7.46,

H. Sashida et al. / Tetrahedron 68 (2012) 10502e10509
10507
7.57, 7.90 (2H, d, J¼7.6 Hz, 2H, dd, J¼7.7, 7.5 Hz, 2H, dd, J¼7.6, 7.5 Hz,
2H, d, J¼7.7 Hz, PheH), 10.17 (2H, s, CHOꢂ2). 13C NMR (125 MHz):
14.1 (q), 21.8 (t), 32.0 (t), 43.0 (t), 124.3 (s), 128.3 (d), 129.0 (d),
130.5 (d), 131.2 (d), 133.6 (s), 133.9 (d), 143.5 (s), 191.5 (d); MS m/z
(relative intensity, %): 634, 632, 630, 628 (Mþ,1, 2, 2,1),187 (100),145
(33), 115 (22); HRMS m/z calcd for C26H30O1230Te2: 634.0370. Found:
634.0370.
%): 450, 448 (Mþ, 1, 1), 145 (100), 115 (22); HRMS m/z calcd for
C20H18O820Se2: 449.9637. Found: 449.9644.
4.3.12. (Z)-Bis(o-formyl-a-n-propylstyryl) diselenide 3Bd. Yield:
153 mg (61%), orange oil. IR (neat, cmꢀ1): 1693 (C]O); 1H NMR
(90 MHz): 0.88, 1.3e1.6, 2.51 (6H, t, J¼7 Hz, 4H, m, 4H, t, J¼7 Hz, n-Pr),
7.00 (2H, s, PheCH]Ceꢂ2), 7.1e7.9 (8H, m, PheH), 10.10 (2H, s,
CHOꢂ2); MS m/z(relative intensity, %): 506, 504 (Mþ,1,1), 237(10),173
(100); HRMS m/z calcd for C24H26O820Se2: 506.0263.Found: 506.0266.
4.3.6. (Z)-Bis(o-formyla-n-octylstyryl) ditelluride 3Af. Yield: 230 mg
(62%), orange oil. IR (neat, cmꢀ1): 1697 (C]O); 1H NMR (500 MHz):
0.90, 1.22e1.38, 1.46e1.56 2.63 (3H, t, J¼7.0 Hz, 20H, m, 4H, 4H, t,
J¼7.5 Hz, n-Oct), 6.96 (2H, s, PheCH]Ceꢂ2), 7.24, 7.45, 7.57, 7.90
(2H, d, J¼7.6 Hz, 2H, dd, J¼7.7, 7.5 Hz, 2H, ddd, J¼7.6, 7.5, 1.2 Hz, 2H, d,
J¼7.7, 1.2 Hz, PheH), 10.18 (2H, s, CHOꢂ2); 13C NMR (125 MHz): 14.2
(q), 22.7 (t), 28.7 (t), 29.3 (t), 29.5 (t), 29.9 (t), 31.9 (t), 43.3 (t), 124.4
(s), 128.3 (d), 130.0 (d), 130.5 (d), 131.1 (d), 133.6 (s), 133.9 (d), 143.5
(s), 191.5 (d); MS m/z (relative intensity, %): 746 (Mþ, 1, 2, 2, 1), 243
(100), 145 (10), 129 (10); HRMS m/z calcd for C34H46O1230Te2:
746.1622. Found: 746.1625.
4.3.13. (Z)-Bis(
a
-n-butyl-o-formylstyryl)
diselenide
3Be. Yield:
202 mg (76%), yellow oil. IR (neat, cmꢀ1): 1695 (C]O); 1H NMR
(500 MHz): 0.8,1.24e1.35,1.15e1.53, 2.49 (6H, t, J¼7.3 Hz, 4H, m, 4H,
m, 4H, t, J¼7.2 Hz, n-Bu), 7.05 (2H, s, PheCH]Ceꢂ2), 7.25, 7.44, 7.56,
7.89 (2H, dd, J¼7.5, 1.1 Hz, 2H, ddd, J¼7.8, 7.5, 1.1 Hz, 2H, ddd, J¼7.5,
7.5, 1.4 Hz, 2H, dd, J¼7.8, 1.4 Hz, PheH), 10.16 (2H, s, CHOꢂ2); 13C
NMR (125 MHz): 14.0 (q), 21.9 (t), 31.0 (t), 38.2 (t),127.1 (d),128.1 (d),
129.3 (d), 131.0 (d), 133.5 (d), 133.6 (s), 140.2 (s), 140.7 (s), 191.6 (d);
MS m/z (relative intensity, %): 534, 532 (Mþ, 1, 1), 267 (2), 187 (100);
HRMS m/z calcd for C26H30O280Se2: 534.0576. Found: 534.0577.
4.3.7. (Z)-Bis(a-cyclohexenyl-o-formylstyryl) ditelluride 3Ag. Yield:
282 mg (83%), orange oil. IR (neat, cmꢀ1): 1691 (C]O); 1H NMR
(90 MHz): 1.15e2.50, 5.75 (16H, m, 2H, br s, cyclohexenyleH), 6.95
(2H, s, PheCH]Ceꢂ2), 7.2e7.9 (8H, m, PheH),10.12 (2H, s, CHOꢂ2);
MS m/z (relative intensity, %): 682 (Mþ, 2, 3, 3, 2), 211 (100),141 (13);
HRMS m/z calcd for C30H30O1230Te2: 682.0372. Found: 682.0374.
4.3.14. (Z)-Bis(o-formyl-
a
-n-octylstyryl)
diselenide
3Bf. Yield:
209 mg (65%), yellow oil. IR (neat, cmꢀ1): 1695 (C]O); 1H NMR
(90 MHz): 0.85, 1.1e1.7, 2.48 (3H, t, J¼6 Hz, 24H, m, 4H, t, J¼7 Hz, n-
Oct), 7.23 (2H, s, PheCH]Ceꢂ2), 7.34, 7.41, 7.52, 7.83 (2H, ddd, J¼7.9,
7.3,0.6 Hz,2H, dd, J¼7.7, 0.6 Hz, 2H, ddd, J¼7.7, 7.3, 1.3 Hz, 2H, dd, J¼7.9,
1.3 Hz, PheH),10.19(2H, s, CHOꢂ2);13CNMR(125 MHz):13.5(q), 22.0
(t), 22.27 (t), 22.31 (t), 22. 4 (t), 34.3 (t), 34.4 (t), 40.4 (t),127.3 (s),128.1
(d),129.1 (d),129.3 (d),129.6 (d),133.5 (s),133.6 (d),140.7 (s),191.6 (s);
MS m/z (relative intensity, %): 646, 644 (Mþ, 1, 1), 307 (15), 243 (100);
HRMS m/z calcd for C34H46O280Se2: 646.1828. Found: 646.1840.
4.3.8. (Z)-Bis(o-formyl-
a
-phenylstyryl)
ditelluride
3Ah. Yield:
262 mg (78%), orange needles, mp 40e45 ꢁC (from CHCl3/hexane).
IR (neat, cmꢀ1): 1693 (C]O); 1H NMR (500 MHz): 7.05 (2H, s,
PheCH]Ceꢂ2), 7.08, 7.20e7.62, 7.84 (2H, d, J¼7.4 Hz, 14H, m, 2H,
dd, J¼7.6, 1.2 Hz, PheH), 10.14 (2H, s, CHOꢂ2); 13C NMR (125 MHz):
123.1 (s), 127.9 (d), 128.0 (d), 128.3 (d), 129.4 (d), 130.0 (d), 130.1 (d),
133.4 (s), 133.7 (d), 135.0 (d), 142.7 (s), 144.4 (s), 191.7 (d); MS m/z
(relative intensity, %): 674 (Mþ, 2, 3, 3, 2), 207 (100), 178 (45); HRMS
m/z calcd for C30H22O1230Te2: 673.9744. Found: 673.9739.
4.3.15. (Z)-Bis(a-cyclohexenyl-o-formylstyryl) diselenide 3Bg. Yield:
211 mg (73%), yellow oil. IR (neat, cmꢀ1): 1691 (C]O); 1H NMR
(900 MHz): 1.38e1.43, 1.47e1.52, 2.03e2.11, 2.21e2.27, 6.00 (4H, m,
4H, m, 4H, m, 4H, m, 2H, t, J¼3.9 Hz, cyclohexenyleH), 6.98 (2H, s,
PheCH]Ceꢂ2), 7.2e7.8 (8H, m, PheH), 10.15 (2H, s, CHOꢂ2); MS
m/z (relative intensity, %): 582, 580 (Mþ, 1, 1), 391 (27), 149 (100);
HRMS m/z calcd for C30H30O280Se2: 582.0576. Found: 582.0573.
4.3.9. (Z)-Bis(a-tert-butyl-o-formylstyryl) diselenide 3Ba. Yield:
234 mg (88%), orange prisms, mp 117e119 ꢁC (from CH2Cl2/hexane).
IR (KBr, cmꢀ1): 1690 (C]O); 1H NMR (500 MHz): 1.17 (18H, s, t-Bu),
7.13 (2H, s, PheCH]Ceꢂ2), 7.26, 7.38, 7.50, 7.84 (2H, d, J¼7.4 Hz, 2H,
dd, J¼7.7, 7.3 Hz, 2H, ddd, J¼7.6, 7.4, 1.4 Hz, 2H, dd, J¼7.7, 1.4 Hz,
PheH), 10.07 (2H, s, CHOꢂ2); 13C NMR (125 MHz): 29.9 (q), 40.3 (s),
127.4 (d), 128.6 (d), 129.5 (d), 131.1 (d), 133.3 (d), 133.4 (s), 142.0 (s),
151.6 (s), 191.6 (d); 77Se NMR (76.3 MHz): 396.7; MS m/z (relative
intensity, %): 534, 532, 530, 528 (Mþ, 2, 2), 187 (100); HRMS m/z
calcd for C26H30O820Se2: 534.0576. Found: 534.0579.
4.3.16. (Z)-Bis(o-benzoyl-a-tert-butylstyryl) ditelluride 6A. Yield:
313 mg (80%), orange oil. IR (neat, cmꢀ1): 1660 (C]O); 1H NMR
(500 MHz): 1.46 (18H, s, t-Bu), 7.47 (2H, s, PheCH]), 6.89, 7.07,
7.41e7.52, 7.53e7.57, 8.06 (2H, ddd, J¼8.4, 6.2, 06 Hz, 2H, ddd,
J¼8.5, 6.3, 0.9 Hz, 8H, m, 4H, m, 2H, d, J¼9.3 Hz, PheH); 13C NMR
(125 MHz): 28.8 (q), 44.6 (s),125.5 (d), 123.9 (d),125.4 (d),126.5 (d),
128.2 (d), 128.9 (d), 129.8 (d), 130.2 (d), 132.4 (s), 139.0 (s), 144.6 (s),
150.6 (s), 206.5 (s); MS m/z (relative intensity, %): 786, 784, 782, 780
(Mþ, 12, 18, 20, 15), 263 (100), 207 (35), 105 (52); HRMS m/z: Mþ
calcd for C38H38O1230Te2: 786.0996. Found: 786.1004.
4.3.10. (Z)-Bis(o-formylstyryl) diselenide 3Bb. Yield: 162 mg (77%),
yellow prisms, mp 75e77 ꢁC (from CH2Cl2/hexane). IR (KBr, cmꢀ1):
1696 (C]O); 1H NMR (500 MHz): 7.20 (2H, d, J¼10.0 Hz, PheCH]
Ceꢂ2), 7.42 (2H, d, J¼10.0 Hz, eCH]CHeSeꢂ2), 7.39, 7.48, 7.60,
7.90 (2H, dd, J¼7.7, 1.0 Hz, 2H, ddd, J¼7.7, 7.5, 1.0 Hz, 2H, ddd, J¼7.7,
7.5, 1.4 Hz, 2H, dd, J¼7.7, 1.4 Hz, PheH), 10.20 (2H, s, CHOꢂ2); 13C
NMR (125 MHz): 128.4 (d), 129.3 (d), 129.4 (d), 129.8 (d), 131.4 (d),
133.1 (s), 133.7 (d), 138.7 (s), 191.7 (d); MS m/z (relative intensity, %):
422, 420 (Mþ, 2, 2),183 (10), 131 (100), 102 (12); HRMS m/z calcd for
C18H14O820Se2: 421.9324. Found: 421.9337.
4.3.17. (Z)-Bis(o-benzoyl-a-tert-butylstyryl) diselenide 6B. Yield:
277 mg (81%), yellow oil. IR (neat, cmꢀ1): 1662 (C]O). 1H NMR
(500 MHz): 0.91 (18H, s, t-Bu), 6.94 (2H, s, PheCH]), 7.27e7.32, 7.70
(14H, m, 4H, dd J¼8.3, 1.3 Hz, PheH); 13C NMR (125 MHz): 29.8 (q),
40.2 (s),126.5 (d),128.2 (d),129.4 (d),130.08 (d),130.09 (d),130.8 (d),
132.54 (d),132.56 (d),138.0 (s),138.1 (s),138.3 (s),148.1 (s),197.5 (s);
MS m/z (relative intensity, %): 686, 684 (Mþ,1,1), 327 (53), 263 (100);
HRMS m/z: Mþ calcd for C38H38O280Se2: 686.1202. Found: 686.1114.
4.3.11. (Z)-Bis(o-formyl-
a-methylstyryl)
diselenide
3Bc. Yield:
123 mg (55%), orange oil. IR (neat, cmꢀ1): 1692 (C]O); 1H NMR
(500 MHz): 2.31 (6H, s, Me), 7.07 (2H, br s, PheCH]Ceꢂ2), 7.28,
7.44, 7.57, 7.89 (2H, d, J¼7.6 Hz, 2H, dd, J¼7.7, 7.6 Hz, 2H, dd, J¼7.6,
7.6 Hz, 2H, d, J¼7.7 Hz, PheH), 10.16 (2H, s, CHOꢂ2); 13C NMR
(125 MHz): 26.6 (q), 127.3 (d), 128.1 (d), 129.6 (d), 130.8 (d), 133.5
(s),133.6 (d),134.8 (s),140.4 (s),191.7 (d); MS m/z (relative intensity,
4.3.18. (Z)-Bis(o-acetyl-a-tert-butylstyryl) diselenide 7B. Yield: 21%,
yellow oil. IR (neat, cmꢀ1): 1679 (C]O); 1H NMR (500 MHz): 1.40
(18H, s, t-Bu), 1.47 (6H, s, COCH3), 7.18 (2H, s, PheCH]), 7.51, 7.54,
7.68, 8.17 (2H, ddd, J¼8.0, 7.1, 1.3 Hz, 2H, dd, J¼8.0, 1.3 Hz, 2H, ddd,
J¼8.0, 7.1, 1.3 Hz, 2H, dd, J¼8.0, 1.3 Hz, PheH); 13C NMR (125 MHz):
31.1 (q), 32.8 (q), 39.1 (s), 118.1 (d), 124.6 (d), 127.5 (s), 128.3 (d),

10508
H. Sashida et al. / Tetrahedron 68 (2012) 10502e10509
131.9 (d), 133.5 (d), 139.3 (s), 155.9 (s), 192.6 (s); MS m/z (relative
intensity, %): 562, 560 (Mþ, 1, 1), 266 (40), 251 (100), 249 (50);
HRMS m/z: Mþ calcd for C28H34O280Se2: 562.0889. Found: 562.0891.
(30 mLꢂ2), dried (MgSO4), and evaporated in vacuo. The residue
was chromatographed on silica gel using n-hexane/CH2Cl2 (1:1) as
eluent to give 3Aa in almost quantitative yield.
4.3.19. (Z)-1-Benzylidene-3-tert-butyl-1H-isotellurochromene
10A. Yield: 58%, pale yellow prisms, mp 104e106 ꢁC (from CHCl3/
hexane). 1H NMR (500 MHz): 1.24 (9H, s, t-Bu), 6.86 (1H, s, 4-H),
7.20, 7.24e7.31, 7.33e7.38, 7.40e7.45, 7.53 (1H, dd, J¼8.0, 1.2 Hz, 3H,
m, 2H, m, 2H, m, 1H, d, J¼7.5 Hz, PheH), 7.49 (s, CH]Ph); 13C NMR
(125 MHz): 30.9 (q), 39.3 (s), 118.8 (s), 125.4 (d), 125.6 (d), 127.7 (d),
128.1 (d), 128.2 (d), 128.3 (d), 128.5 (d), 131.0 (d), 133.4 (s), 136.8 (s),
137.2 (d), 139.4 (s), 140.2 (s).
4.6. Hydrolysis of telluropyrylium salts 17A and selenopyry-
lium salts 17B
H2O (6 mL) was added to a suspended solution of the pyrylium
salts 16 (0.3 mmol) in Et2O (12 mL). The reaction mixture was
vigorously stirred at room temperature for 30 min, and extracted
with Et2O (20 mLꢂ3). The organic layer was washed with brine
(30 mLꢂ2), dried (MgSO4), and evaporated in vacuo. The residue
was chromatographed on silica gel using n-hexane/CH2Cl2 (1:1) as
eluent to give 3 and 18.
4.3.20. (Z)-1-Benzylidene-3-tert-butyl-1H-isoselenochromene
10B. Yield: 64%, pale yellow prisms, mp 127e128 ꢁC (from CHCl3/
hexane). 1H NMR (500 MHz): 1.25 (9H, s, t-Bu), 6.72 (1H, s, 4-H),
7.21 (1H, s, CH]Ph), 7.14, 7.22e7.30, 7.33e7.44, 7.55 (1H, dd,
J¼7.5 Hz, 3H, m, 4H, m, 1H, d, J¼7.6 Hz, PheH); 13C NMR (125 MHz):
30.2 (q), 38.0 (s), 119.1 (d), 125.0 (d), 127.1 (d), 128.0 (d), 128.1 (d),
128.3 (d), 129.0 (d), 129.1 (d), 129.3 (s), 129.6 (d), 131.0 (s), 134.2 (s),
137.2 (s), 147.6 (s).
4.6.1. (Z)-Bis(a-tert-butyl-o-formylstyryl) ditelluride 3Aa. Yield: 92%.
4.6.2. (Z)-Bis(o-formylstyryl) ditelluride 3Ab. Yield: 24%.
4.6.3. (Z)-Bis(a-tert-butyl-o-formylstyryl) diselenide 3Ba. Yield: 10%.
Yellow prisms, mp 117e119 ꢁC (from CHCl3/hexane).
4.3.21. (Z)-1-n-Butylidene-3-tert-butyl-1H-isotellurochromene
11A. Yield: 60%, orange oil. 1H NMR (90 MHz): 1.27 (9H, s, t-Bu),
0.93, 1.30e1.70, 2.10e2.40 (3H, t, J¼7.6 Hz, 2H, m, 2H, m, n-Pr), 6.19
(1H, t, J¼7 Hz, C]CHen-Pr), 6.75 (1H, s, PheCH]), 7.00e7.50 (4H,
4.6.4. 3-tert-Butyl-1-hydroxy-1H-isoselenochromene 18. Yield: 89%,
yellow oil. IR (neat, cmꢀ1): 3388 (OH). 1H NMR (90 MHz): 1.31 (9H,
s, t-Bu), 2.37 (1H, d, J¼8 Hz, OH), 6.02 (1H, d, J¼8 Hz, 1-H), 6.90 (1H,
s, 4-H), 7.3e7.4 (4H, m, PheH); MS m/z (relative intensity, %): 268
(Mþ, 100), 187 (79), 131 (48), 115 (17); HRMS m/z: Mþ calcd for
C13H16OSe: 268.0366. Found: 268.0372.
m, PheH); MS m/z (relative intensity, %): 356 (Mþ, 100), 354 (85),
130
327 (45), 301 (60); HRMS m/z: Mþ calcd for C17
H
Te: 356.0784.
22
Found: 356.0786.
4.7. (o-Formylstyryl)tellurium(IV) trichloride 19
4.3.22. (Z)-3-tert-Butyl-1-n-butylidene-1H-isoselenochromene
11B. Yield: 65%, yellow oil. 1H NMR (90 MHz): 1.30 (9H, s, t-Bu),
0.98, 1.48e1.00, 2.25 (3H, t, J¼7 Hz, 2H, m, 2H, m, n-Pr), 6.12 (1H, t,
J¼7 Hz, C]CHen-Pr), 6.67 (1H, s, PheCH]), 7.15e7.43 (4H, m,
SO2Cl2 (five drops, 92 mg) was added to a solution of the o-
formylstyryl ditelluride 3A (0.5 mmol) in dry CH2Cl2 (2 mL) at 0 ꢁC.
The reaction mixture was vigorously stirred at room temperature
for 30 min, and evaporated. The resulting residue was recrystallized
from Et2O or CH2Cl2/hexane.
PheH); MS m/z (relative intensity, %): 306 (Mþ, 90), 304 (60), 277
80
(100), 275 (81), 165 (36); HRMS m/z: Mþ calcd for C17
H Se:
22
306.0887. Found: 306.0883.
4.7.1.
a-tert-Butyl-o-formylstyryltellurium(IV) trichloride 19a. Yield:
95%, colorless prisms, mp 216e218 ꢁC (decomp. from Et2O). IR (KBr,
cmꢀ1): 1681 (C]O); 1H NMR (500 MHz): 1.69 (9H, s, t-Bu),
7.15e7.80, 7.94, 8.05 (2H, m, 1H, dd, J¼6.1, 1.5 Hz, 1H, dd, J¼6.7,
2.2 Hz, PheH), 8.08 (1H, s, PheCH]), 10.11 (1H, s, CHO); 13C NMR
(125 MHz): 30.3 (q), 45.4 (s), 131.0 (d), 131.8 (d), 132.1 (d), 133.0 (s),
133.3 (d), 134.3 (d), 135.5 (s), 164.7 (s), 190.4 (d); MS m/z (relative
intensity, %): 389 (MþꢀCl, 5), 351 (3), 307 (25), 301 (30), 187 (100).
4.4. 1-Acetoxy-3-tert-butyl-1H-isotellurochromene 16
m-CPBA (70%, 296 mg, 1.2 mmol) was added to a solution of 3-
tert-butylisotellurochromene (1Aa, 302 mg, 1.0 mmol) in dry
CHCl3 (10 mL) at 0 ꢁC under argon atmosphere and the mixture
was stirred under same conditions. After 30 min, Ac2O (1.0 mL)
was added to the reaction mixture and stirred for another 1 h.
The reaction mixture was quenched with water (10 mL), the
aqueous mixture was extracted with CH2Cl2 (50 mLꢂ3). The or-
ganic layers were washed with brine (30 mLꢂ2), dried (MgSO4),
and evaporated. The residue was triturated and extracted with
hexane, and filtrated to remove m-chlorobenzoic acid. The filtrate
was evaporated to provide 1-acetoxyisotellurochromene in an
almost pure state. Yellow oil. IR (neat, cmꢀ1): 1697 (C]O); 1H
NMR (90 MHz): 1.51 (9H, s, t-Bu), 2.15 (3H, s, COCH3), 4.94 (1H, s,
1-H), 7.33 (1H, s, 4-H), 7.22e7.93 (4H, m, PheH); MS m/z (relative
intensity, %): 360 (Mþ, 5), 301 (65), 187 (18), 156 (75), 139 (100);
HRMS m/z: Mþ calcd for C15H18O1230Te: 360.0369. Found:
360.0368.
4.7.2. o-Formyl-a-methylstyryltellurium(IV) trichloride 19c. Yield:
84%, colorless prisms, mp 107e109 ꢁC (decomp. from CH2Cl2/hex-
ane); IR (KBr, cmꢀ1): 1704 (C]O); 1H NMR (500 MHz): 2.95 (3H, s,
Me), 7.41e7.82, 7.96e8.08 (2H, m, 2H, m, PheH), 8.19 (1H, s,
PheCH]),10.01 (1H, s, CHO); MS m/z (relative intensity, %): 347, 345,
343, 341 (MþꢀCl, 3, 8, 7, 3), 274 (11), 272 (10), 145 (100), 115 (45).
4.8. Crystal data for 3Aa
Single crystals of 3Aa were obtained from solutions of acetone/
hexane after slow evaporation of the solvents at room temperature.
Diffraction data were collected on a Bruker Apex-II CCD diffrac-
4.5. Hydrolysis of 1-acetoxy-3-tert-butyl-1H-isotellurochromene
16: formation of 3Aa
tometer equipped with a graphite monochromated Mo Ka radia-
ꢀ
tion source (
l
¼0.71073 A). The structures were solved by direct
methods (SHELXS-97), and refined by full-matrix least-square
methods on F2 for all reflections (SHELXL-97) with all non-
hydrogen atoms anisotropic and all hydrogen atoms isotropic.
For 3Aa, the structure analysis is based on 2511 observed re-
To the obtained crude 1-acetoxyisotellurochromene 16 in CHCl3
(10 mL) was added satd aq NaHCO3 (5 mL mL). The reaction mix-
ture was vigorously stirred at room temperature, immediately be-
came reddish orange color. The mixture was extracted with CH2Cl2
(10 mLꢂ2), the combined organic layer was washed with brine
flections with I>2.00
s(I) and 139 variable parameters; red prisms,
C26H30O2Te2, FW¼629.7, 113 K, orthorhombic, space group Pbcn,

H. Sashida et al. / Tetrahedron 68 (2012) 10502e10509
10509
3
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ꢀ
ꢀ
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Minoura, M. Tetrahedron Lett. 2010, 51, 5395e5398; (f) Kaname, M.; Minoura,
M.; Sashida, H. Tetrahedron Lett. 2011, 52, 505e508; (g) Kaname, M.; Sashida, H.
Tetrahedron Lett. 2011, 52, 3279e3382; (h) Sashida, H.; Kaname, M. Heterocycles
2012, 84, 669e682; (i) Kaname, M.; Sashida, H. Tetrahedron Lett. 2012, 53,
748e751.
4. Reviews: (a) Sashida, H. Rev. Heteroat. Chem. 2000, 22, 59e78; (b) Sashida, H. J.
Synth. Org. Chem. Jpn. 2001, 59, 355e362; (c) Sashida, H. Mini-Rev. Org. Chem.
2007, 4, 105e114; (d) Sashida, H.; Minoura, M. J. Synth. Org. Chem. Jpn. 2009, 67,
714e723; (e) Sashida, H. Heterocycles 2011, 83, 2223e2254.
5. (a) Sashida, H.; Ohyanagi, K. J. Chem. Soc., Perkin Trans. 1 1998, 2123e2124; (b)
Sashida, H.; Satoh, H.; Ohyanagi, K. Heterocycles 1999, 51, 17e20.
6. (a) Sashida, H.; Ohyanagi, K.; Minoura, M.; Akiba, K.-y. J. Chem. Soc., Perkin Trans.
1 2002, 606e612; (b) Sashida, H.; Ohyanagi, K. Chem. Pharm. Bull. 2004, 52,
57e62; (c) Sashida, H.; Satoh, H.; Ohyanagi, K. Heterocycles 2004, 63, 309e317;
(d) Sashida, H.; Ohyanagi, K. Chem. Pharm. Bull. 2005, 53, 60e63; (e) Ohyanagi,
K.; Sashida, H. Heterocycles 2006, 68, 505e513.
a¼11.027(4) A, b¼19.194(7) A, c¼11.662(5) A, V¼2468.3(2) A , Z¼4,
R¼0.0533, Rw¼0.1365, GOF¼1.163.
CCDC 881933 for 3Aa contains the supplementary crystallo-
graphic data for this paper. The data can be obtained free of charge
from the Cambridge Crystallographic Data Centre via http://
www.ccdc.cam.ac.uk/products/csd/request/.
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 (Nos. 19590022, 23590023). The
authors wish to thank to Mr. Hirohito Sato (Hokuriku University)
for his technical assistance.
7. Sashida, H. Synthesis 1999, 1866e1868.
8. A part of this work has been appeared in a preliminary communication:
Sashida, H.; Satoh, H.; Ohyanagi, K.; Kaname, M. Molecules 2010, 15,
1466e1472.
9. Uemura, S. Rev. Heteroat. Chem. 1990, 3, 105e120.
10. Drevko, B. I.; Fomenko, L. A.; Kharchenko, V. G. Khim. Geterotsikl. Soedin. 1989,
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22
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