Hydrotelluration and carbotelluration of acetylenic sulfoxides: Regio- and stereoselective preparation of α- and β-organotellurovinyl sulfoxides

Article abstract of DOI:10.1016/j.tetlet.2004.02.064

(Z)-β-Organotellurovinyl sulfoxides were synthesized via a highly regio- and stereoselective anti-hydrotelluration of acetylenic sulfoxides. α-Organotellurovinyl sulfoxides were obtained from a three component syn-carbotelluration reaction of acetylenic s

Full text of DOI:10.1016/j.tetlet.2004.02.064

Tetrahedron
Letters
Tetrahedron Letters 45 (2004) 2981–2984
Hydrotelluration and carbotelluration of acetylenic sulfoxides:
regio- and stereoselective preparation of a- and b-organotellurovinyl
sulfoxides
a
Qing Xu,a Xian Huanga,b, and Jun Ni
*
aDepartment of Chemistry, Zhejiang University (Xixi Campus), Hangzhou 310028, PR China
bState Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences,
354 Fenglin Lu, Shanghai 200032, PR China
Received 23 October 2003; revised 28 January 2004; accepted 4 February 2004
Abstract—(Z)-b-Organotellurovinyl sulfoxides were synthesized via a highly regio- and stereoselective anti-hydrotelluration of
acetylenic sulfoxides. a-Organotellurovinyl sulfoxides were obtained from a three component syn-carbotelluration reaction of
acetylenic sulfoxides, that is, syn-addition of monoorganocopper reagents to acetylenic sulfoxides followed by the electrophilic
reaction of the vinyl copper intermediates with benzenetellurenyl iodide at low temperature. Synthetic applications of the
organotellurovinyl sulfoxides have been investigated.
Ó 2004 Elsevier Ltd. All rights reserved.
Stereoselective synthesis of substituted alkenes has
drawn a lot of attention in organic synthesis, in which
the transformations of vinylic and acetylenic chalcogen
compounds are one of the most efficient routes to stereo-
defined alkenes.1 Vinyltellurides are especially important
synthetic intermediates because of their ready conver-
sion to other intermediates or compounds with excellent
retention of the configuration.1;2 Regio- and stereo-
selective preparation of a- and b-functionalized vinyl
tellurides3;4 are still hot topics of research because of
their potential applications in organic synthesis.1;5
organic synthesis7 and we have studied the regio- and
stereoselective hydrozirconation of acetylenic sulfoxides8
to prepare substituted vinyl sulfoxides.6b As a part of our
ongoing studies we wish to report the anti-hydro-
telluration and three component syn-carbotelluration of
acetylenic sulfoxides to prepare b- and a-organotelluro-
vinyl sulfoxides, respectively.
Acetylenic sulfoxides were added to a EtOH/THF
solution of sodium phenyltellurolate, prepared in situ
from diorganoditelluride and sodium boronhydride, at
room temperature to afford high yields of b-organo-
tellurovinyl sulfoxides (Scheme 1).9 The J value of the
two vinyl protons in compound 2a (J ¼ 9:20 Hz) shows
they are in a syn-relationship, which indicates the
hydrotelluration of acetylenic sulfoxides is an anti-
addition reaction.10 Results of these reactions are sum-
marized in Table 1.
We are also interested in the synthesis and applications
of stereo-defined functionalized vinyl chalcogenides.6
Recently, our group has reported the anti-hydrotellura-
tion of acetylenic sulfones and acetylenic phosphonates,6i
free radical tellurosulfonation of acetylenes,6i seleno-
magenization of acetylenic sulfones,6c;d and seleno-
lithiation of acetylenic phosphine oxides6f to prepare
functionalized vinyl chalcogenides. On the other hand,
substituted vinyl sulfoxides, especially the optically pure
ones, are very important synthetic intermediates in
THF/EtOH
[ R2TeNa ]
R1
(R2Te)2
+
NaBH4
r.t.
[ R2TeNa ]
H
R1
SOAr
R2Te
SOAr
THF/EtOH,
r.t., 30 min.
Keywords: Organotellurovinyl sulfoxides; Hydrotelluration; Carbo-
telluration.
2
1
* Corresponding author. Fax: +86-571-88807077; e-mail: huangx@
mail.hz.zj.cn
Scheme 1.
0040-4039/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2004.02.064

2982
Q. Xu et al. / Tetrahedron Letters 45 (2004) 2981–2984
Table 1. Synthesis of (Z)-b-organotellurovinyl sulfoxides
2
°
R1
R2
SOAr
E
1. R Cu, -78 C
R1
R1
Ar
R2
Yield (%)a
SOAr
Product
°
2. i or ii, -78 C~ r.t.
2a
2b
2c
2d
2e
2f
H
p-Tol
p-Tol
Ph
Ph
Ph
85
93
89
84
92
81
96
90
5, E = H, 91%
6, E = TePh
1
n-C4H9
n-C4H9
n-C4H9
n-C5H11
n-C5H11
n-C6H13
n-C6H13
Ph
Conditions: i, NH4Cl/H2O
ii, PhTeI
Ph
p-Tol
Ph
n-C4H9
Ph
Ph
Scheme 3.
2g
2h
p-Tol
Ph
Ph
Ph
a Isolated yield based on acetylenic sulfoxide.
was then applied to the synthesis of a-organotelluro-
vinyl sulfoxides (Scheme 3).13 After the syn-addition
reaction of the monoorganocopper reagent to the acet-
ylenic sulfoxides was completed, benzenetellurenyl
iodide, prepared in situ from diphenyl ditelluride and
iodine at 0 °C, was added dropwise at )78 °C. The
a-organotellurovinyl sulfoxides were afforded in mod-
erate to good yields as the sole product. The reaction of
allyl copper reagents can also afford the expected
products but with slightly lower yield (Product 6c). This
might result from the different reactivity of allyl copper
reagents compared to normal copper reagents since
other undetermined products were also found. The
results of these reactions are summarized in Table 2.
Notably, in the case of phenylacetylenyl aryl sulfoxides
small amounts of the detellurolated side products (E)-
phenylvinyl aryl sulfoxides 3a and 3b were obtained in
addition to the main products 2i and 2j (Scheme 2).
Compound 2i and 2j were found to be unstable and thus
were quickly converted to dibromides 4 by the addition
of 1.0 equiv of bromine in methanol at 0 °C.
a-Functionalized vinyl tellurides are another class of
compounds that have received great recognition.1;3
Therefore we also prepared a-organotellurovinyl sulf-
oxides. We found that use of an organocopper reagent11
was a direct and efficient protocol to obtain such
a-organotellurovinyl sulfoxides with predicted configu-
ration. Literature reports12 show that monoorganocop-
per reagents are not only more suitable Michael addition
reagents to acetylenic sulfoxides than are diorganocop-
per reagent, but they also exhibit excellent regio- and
stereochemistry. Therefore, we investigated the two
component reaction of monoorganocopper reagents
with acetylenic sulfoxides to examine the regio- and
stereochemistry of these addition reactions (Scheme 3).
When the addition reaction of the phenylcopper reagent
prepared in situ from CuI and 1.0 equiv of phenylmag-
nesium bromide with butynyl p-tolyl sulfoxide at )78 °C
was completed as monitored by TLC, the reaction
mixture was quenched with saturated aqueous ammo-
nium chloride at this temperature. High yield of the
product 5 (R1 ¼ n-Bu, R2 ¼ Ph, E ¼ H) was obtained
after workup and purification. Spectroscopic data of 5
was found to be identical to the previous report,7a which
indicates that the conjugate addition of monoorgano-
copper reagents to acetylenic sulfoxides is cis-specific, as
reported.12 The above syn-conjugate addition reaction
We postulated that the presence of the sulfinyl group in
the acetylenic sulfoxides is the key factor for controlling
the observed excellent regio- and stereoselectivity in the
above anti-hydrotelluration and syn-carbotelluration
reactions, since the electron withdrawing sulfinyl group
is a relatively strong inductive group, just as sulfone and
phosphonate groups are, and therefore they afford the
products with controlled regio- and stereoselectivity.
With the organotellurovinyl sulfoxides in hand, we set
out to study their applications in the preparation of
poly-substituted vinyl sulfoxides, since the reactive tel-
lurium group is a good precursor in many transforma-
Table 2. Synthesis of a-organotellurovinyl sulfoxides
Product
R1
R2
Ar
Yield (%)a
6a
6b
6c
6d
n-C4H9
n-C4H9
n-C4H9
n-C5H11
Et
Ph
p-Tol
p-Tol
p-Tol
p-Tol
79
85
34
76
Allyl
Et
a Isolated yield based on acetylenic sulfoxide.
[ PhTeNa ]
Ph
H
Ph
H
H
Ph
SOAr
+
THF/EtOH,
r.t., 10 min.
PhTe
SOAr
SOAr
1
3
2
Ar = p-Tolyl, 2i, 76 %, 3a, 9 %
Ar = Ph, 2j, 69 %, 3b, 10%
Br2 (1.0 equiv.),MeOH
Ph
H
PhBr2Te
SOAr
4
Scheme 2.

Q. Xu et al. / Tetrahedron Letters 45 (2004) 2981–2984
2983
R1
H
R1
R2
R1
PhTe
H
R22 CuMgBr
H
R3C CH, PdCl2, CuI
Et3N, MeOH, r.t.
SOp-Tol
°
-15 C
SOp-Tol
SOp-Tol
R3
2
8, 63%
7, 82%
R1 = H, R2 = Ph
R1 = H, R3 = CH3OCH2
°
1. EtMgBr, -78 C
4
°
2. R CHO, -78 C
R1
H
R4
SOp-Tol
OH
9, 54%
R1 = n-C5H11, R4 = Ph
Scheme 4.
tions.1;2;5 As shown in Scheme 4, the substitution reac-
tions of (Z)-b-organotellurovinyl sulfoxides 2a with
diorganocopper reagents at )15 °C afforded good yields
of vinyl sulfoxides 7 with the total retention of config-
uration. The J value of the two vinyl protons,
J ¼ 10:40 Hz, shows they are in a syn-relationship.
Compound 2a can also couple with terminal acetylenes
in the presence of a catalytic amount of PdCl2 and CuI
in methanol to afford conjugate sulfinyl enyne 8 that
also exhibit retention of configuration (J ¼ 10.0 Hz). The
Te/Mg exchange reaction of 2e with ethyl magnesium
bromide followed by the electrophilic reaction with
benzaldehyde afforded sulfinyl group substituted allyl
alcohol 9. On the other hand, the sulfinyl group itself is a
potential reaction center. It is not only a very good
leaving group both in ionic14 and free radical reac-
tions,15 but it can also undergo substitution reactions
with several organometallic reagents.16 Therefore, the
above obtained vinyl sulfoxides are versatile intermedi-
ates with many potential synthetic uses.
2. (a) Dabdoub, M. J.; Begnini, M. L.; Guerrero, P. G., Jr.
Tetrahedron 1998, 54, 2371; (b) Dabdoub, M. J.; Justino,
A.; Guerrero, P. G., Jr. Organometallics 1998, 17, 1901; (c)
Dabdoub, M. J.; Baroni, C. M. J. Org. Chem. 2000, 65, 54;
(d) Dabdoub, M. J.; Begnini, M. L.; Guerrero, P. G., Jr.;
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Dabdoub, M. J.; Dabdoub, V. B.; Pereira, M. A.
Tetrahedron Lett. 2001, 42, 1595; (d) Braga, A. L.; Vargas,
F.; Zeni, G.; Silvera, C. C.; de Andrade, L. H. Tetrahedron
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met. Chem. 1996, 507, 197; (b) Ohe, K.; Takahashi, H.;
Uemura, S.; Sugita, N. J. Org. Chem. 1987, 52, 4859; (c)
Zeni, G.; Nogueira, C. W.; Pena, J. M.; Pilissao, C.;
Menezes, P. H.; Braga, A. L.; Rocha, J. B. T. Synlett 2003,
579; (d) Braga, A. L.; de Andrade, L. H.; Silvera, C. C.;
Moro, A. V.; Zeni, G. Tetrahedron Lett. 2001, 42, 8563.
6. (a) Huang, X.; Duan, D. H. Chem. Commun. 1999, 1741;
(b) Huang, X.; Duan, D. H.; Zheng, W. X. J. Org. Chem.
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4, 1331; (d) Huang, X.; Xie, M. H. J. Org. Chem. 2002, 67,
8895–8900; (e) Huang, X.; Xu, Q.; Liang, C. G.; He, Q. W.
Synth. Commun. 2002, 1243; (f) Huang, X.; Xiong, Z. C.
Chem. Commun. 2003, 1714; (g) Huang, X.; Sun, A. M. J.
Org. Chem. 2000, 65, 6561; (h) Zhao, C. Q.; Huang, X.;
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X.; Liang, C. G.; Xu, Q.; He, Q. W. J. Org. Chem. 2001,
66, 74.
In summary, we have developed efficient methods for
the regio- and stereoselective preparation of a- and b-
organotellurovinyl sulfoxides from the readily available
acetylenic sulfoxides. Preliminary application studies
have demonstrated the utility of organotellurovinyl
sulfoxides as precursors for certain potentially useful
compounds in organic synthesis.
Acknowledgements
7. (a) Garcia Ruano, J. L.; Garcia, M. C.; Matin Castro, A.
M.; Rodriguez Ramos, J. H. Org. Lett. 2002, 4, 55; (b)
Garcia Ruano, J. L.; Gamboa, A. E.; Matin Castro, A.
M.; Rodriguez Ramos, J. H.; Lopez-Solera, M. I. J. Org.
Chem. 1998, 63, 3324; (c) Narita, M.; Urabe, H.; Sato, F.
Angew. Chem., Int. Ed. 2002, 41, 3671; (d) Carretero, J. C.;
Adrio, J. Synthesis 2001, 1888.
We are grateful to the National Natural Science Foun-
dation of China (Project Nos. 20272050, 20332060) for
financial support.
8. Kosugi, H.; Kitaoka, M.; Tagami, K.; Takahashi, A.
J. Org. Chem. 1987, 52, 1078.
References and notes
9. Typical procedure for the preparation of (Z)-b-organotel-
lurovinyl sulfoxides 2: Sodium boronhydride in EtOH was
added dropwise to the solution of diorganoditelluride
1. Comasseto, J. V.; Ling, L. W.; Petragnani, N.; Stefani, H.
A. Synthesis 1997, 373.

2984
Q. Xu et al. / Tetrahedron Letters 45 (2004) 2981–2984
(0.5 mmol) in THF (3 mL) under N2. The characteristic
syringe. The reaction mixture was stirred at a temperature
not higher than )50 °C for 1 h and then was cooled to
)78 °C again. Bezenetellurenyl iodide (0.75 mmol), pre-
pared in situ from diphenyl ditelluride and iodine in THF
at 0 °C, was then added dropwise. After the temperature
was gradually returned to room temperature, the mixture
was washed with saturated aqueous NH4Cl and NaCl,
abstracted with EtOAc, dried over MgSO4. The solvent
was evaporated and the residue purified by TLC to afford
the product 6. Selected data of compound 6b: Pale yellow
solid, mp 104–106 °C. 1H NMR (400 MHz, CDCl3): d
7.61–7.59 (d, J ¼ 8:40 Hz, 2H), 7.32–7.30 (d, J ¼ 8:00 Hz,
2H), 7.22–7.12 (m, 3H), 7.08–7.04 (m, 1H), 6.92–6.89 (m,
2H), 6.86–6.80 (m, 4H), 3.35–3.28 (m, 1H), 2.97–2.90 (m,
1H), 2.43 (s, 3H), 1.46–1.33 (m, 4H), 0.91–0.87 (t,
dark-red color of the ditelluride gradually faded and
turned to colorless, and then acetylenic sulfoxide in THF
was added and the mixture was stirred at room temper-
ature for 30 min, quenched with saturated aqueous
NH4Cl, and extracted with EtOAc. The organic phase
was dried over sodium sulfate and concentrated under
vacuum. The residue was purified by preparative TLC on
silica gel (eluent: AcOEt:n-hexane ¼ 1:5) to give com-
pounds 2 in high yields.
10. Selected data of compound 2a: Pale yellow solid, mp 73–
75 °C. 1H NMR (400 MHz, CDCl3): d 7.88–7.86 (d,
J ¼ 9:20 Hz, 1H), 7.83–7.81 (dd, J ¼ 0:80 Hz, J ¼ 8:0 Hz,
2H), 7.66–7.64 (d, J ¼ 8:0 Hz, 2H), 7.36–7.28 (m, 5H),
7.02–7.00 (d, J ¼ 9:20 Hz, 1H), 2.43 (s, 3H). 13C NMR
(400 MHz, CDCl3): d 142.8, 140.2, 138.4, 132.8, 13.06,
129.8, 128.5, 125.6, 120.7, 119.8, 22.0. MS (EI) m=z (%)
372 (18, Mþ), 356 (2), 265 (17), 207 (10), 165 (10), 139 (43),
123 (6), 91 (32), 77 (100). IR (KBr) cmꢀ1 3052, 2922, 1594,
1574, 1545, 1492, 1475, 1435, 1399, 1327, 1180, 1143, 1120,
1080, 1032, 1014, 910. Anal. Calcd for C15H14OSTe: C,
48.70; H, 3.814. Found: C, 48.45; H, 3.853.
J ¼ 7:20 Hz, 3H). 13C NMR (400 MHz, CDCl3):
d
163.31, 143.03, 141.38, 138.96, 135.99, 129.96, 128.73,
128.14, 128.03, 127.90, 127.57, 125.41, 114.85, 38.10,
30.97, 22.81, 21.85, 14.22. MS (EI) m=z (%) 505 (Mþ+1,
6), 504 (Mþ, 2), 427 (2), 397 (2), 314 (7), 207 (9), 157 (100),
139 (15), 129 (16), 115 (21), 103 (7), 91 (29), 77 (39). IR
(KBr) cmꢀ1 3053, 2956, 2926, 2860, 1573, 1490, 1473,
1434, 1379, 1301, 1082, 1048, 1017, 998, 912. Anal. Calcd
for C25H26OSTe: C, 59.80; H, 5.219. Found: C, 59.43; H,
5.261.
11. (a) Normant, J. F.; Alexakis, A. Synthesis 1981, 841; (b)
Erdik, E. Tetrahedron 1984, 40, 641.
12. Truce, W. E.; Lusch, M. J. J. Org. Chem. 1978, 43, 2252.
13. Typical procedure for the preparation of a-organotelluro-
vinyl sulfoxides 6: Alkyl or aryl magnesium bromide
(0.75 mmol) in dry THF or ether was added at 0 °C to the
THF suspension of CuI (0.75 mmol) in a tube reactor
under nitrogen to form the monoorganocopper reagents.
The mixture was then cooled to )78 °C and the acetylenic
sulfoxide (0.5 mmol) in dry THF was injected with a
14. Satoh, T.; Hanali, N.; Kuramochi, Y.; Inoue, Y.; Hosoya,
K.; Sakai, K. Tetrahedron 2002, 58, 2533.
15. Delouvrie, B.; Lacote, E.; Fensterbank, L.; Malacria, M.
Tetrahedron Lett. 1999, 40, 3565.
16. (a) Ma, S.-M.; Ren, H.-J.; Wei, Q. J. Am. Chem. Soc.
2003, 125, 4817; (b) Farhat, S.; Marek, I. Angew. Chem.,
Int. Ed. 2002, 40, 1410.