4
170
J . Org. Chem. 1998, 63, 4170-4171
Tellu r oa cyla tive Ad d ition of Tellu r oester s to
Ter m in a l Alk yn es Ca ta lyzed by Cu p r ou s
Iod id e
Sch em e 1
Chang-Qiu Zhao, J in-Liang Li, J i-Ben Meng,* and
Yong-Mei Wang
Department of Chemistry, Nankai University,
Tianjin, 300071, P. R. China
Received April 14, 1998
Research on vinyl selenides and tellurides has attracted
considerable attention in recent years due to the varied
reactivity of their selenium and tellurium atoms. These
compounds can normally be prepared from the addition
reactions of selenium and tellurium reagents with alkynes
or from the elimination reactions of saturated (haloalkyl)se-
lenides and tellurides.1 The bifunctional addition reactions
involving selenium and tellurium atoms have recently been
developed as useful methods for preparation of vinyl se-
lenides and tellurides with various functional groups.2
Among them, the addition reactions involving the simulta-
neous introduction of carbon-centering functional groups
have special importance for organic synthesis.3 Han et al.
have reported the radical addition of diorganyl tellurides to
alkynes to afford (â-alkylvinyl)tellurides.4 Now we have
developed a practical method for the preparation of (Z)-â-
Sch em e 2
halide that was produced during the formation of cuprous
alkynylides 1. Arenetellurols 6 would add to R,â-alkynones
4 nucleophilicly to form the adducts 7. The above assump-
tion is shown in Scheme 1.
Telluroesters 2 were prepared by the reaction of arylmag-
nesium bromides with powder tellurium, followed by the
acylation with acyl chlorides.7 The experimental results
indicated that when the mixture of telluroesters 2 and
terminal alkynes 3 was heated in anhydrous dimethylfor-
mamide in the presence of cuprous iodide and triethylamine
for 1 h and then was exposed to the air, R,â-alkynones 4
and diaryl ditellurides 8 were isolated in 86-89% and 91-
94% yields, respectively. In addition, a trace amount of
(aryltelluro)-R,â-unsaturated ketones via Cu(I)-catalyzed
telluroacylative addition of telluroesters to terminal alkynes,
with which the aryl tellurenyl and acyl groups were simul-
taneously introduced to the organic molecules.
It has been reported that cuprous alkynylides could be
5
1
acylated with acyl chlorides to produce R,â-alkynones.
yellowish solids was isolated and characterized by IR, H
NMR, and MS as (Z)-â-aryltelluro-R,â-unsaturated ketones
Considering that the C-Te bond of telluroesters is weak and
very easy to be broken,3 we assumed that telluroesters 2
would have the reactivity toward cuprous alkynylides simi-
lar to that of acyl chlorides. Cuprous alkynylides 1, formed
from alkynes 3 and cuprous halide in the presence of organic
a
7.
The isolation of diaryl ditellurides 8 implied that the
anions of tellurides, which are readily oxidized by oxygen
to give 8, may be formed. Phenylethyne reacted with
telluroesters to afford mainly R,â-alkynones 4 and diaryl
ditellurides 8, while the additive products were isolated in
less than 10% yields. We assumed that the acidification and
addition of cuprous aryl tellurides to R,â-alkynones 4 (eqs 3
and 4 in Scheme 1) would be the rate-determining steps of
the reaction. Thus, after the telluroesters disappeared in
the above reaction, trimethylamine hydrochloride was added
to ensure that cuprous aryl tellurides 5 be converted to
arenetellurols 6, which then add to 4 as quickly as possible.
In this case, the addition reaction of telluroesters with
alkynes was completed within 8 h when heated at 60-70
°C, producing the adducts 7 with high stereoselectivity in
high yields (Scheme 2 and Table 1).
Through the above procedure only (Z)-adducts were
isolated, whose configuration was confirmed based on the
study of H NMR. In a difference NOE experiment of 7e,
irradiation of the peak of phenyl at δ 6.99 responded to the
vinylic protons (δ 8.04) with 7% enhancement. The ortho-
protons of carbonyl in p-chlorobenzoyl (δ 8.00) showed 4%
6
base, were expected to be directly acylated by telluroesters
2
in a similar manner to afford R,â-alkynones 4 and cuprous
tellurides 5. It was expected that the cuprous aryl tellurides
be converted to arenetellurols 6 by triethylamine hydro-
5
(
1) For recent reviews about vinyl selenides and tellurides see: (a)
Comasseto, J . V.; Ling, L. W.; Petragnani, N.; Stefani, H. A. Synthesis 1997,
73. (b) Comasseto, J . V. J . Organomet. Chem. 1983, 253, 134.
2) For bifunctional addition of X-Y bonds (X ) Se, Te; Y ) P, S, Si,
3
(
etc.) to alkynes, see the following: (a) Han, L.-B.; Choi, N.; Tanaka, M. J .
Am. Chem. Soc. 1996, 118, 7000. (b) Kanda, T.; Koike, T.; Kagohashi, S.;
Mizoguhi, K.; Murai, T.; Kato, S. Organometallics 1995, 14, 4975. (c) Back,
T. G.; Collins, S.; Kerr, R. G. J . Org. Chem. 1983, 48, 3077. (d) Back, T. G.;
Collins, S. J . Org. Chem. 1981, 46, 3249. (e) Ogawa, A.; Obayashi, R.; Ine,
H.; Tsuboi, Y.; Sonoda, N.; Hirao, T. J . Org. Chem. 1998, 63, 881. (f) Murai,
T.; Nonomura, K.; Kato, S. Organometallics 1991, 10, 1095. (g) Ogawa, A.;
Sonoda, N. J . Synth. Org. Chem. J pn. 1993, 51, 815.
8
(3) (a) Crich, D.; Chen, C.; Hwang, J .; Yuan, H.; Papadatos, A.; Walter,
R. I. J . Am. Chem. Soc. 1994, 116, 8937. (b) Kuniyasu, H.; Ogawa, A.;
Miyazaki, S.-I.; Rau, I.; Kambe, N.; Sonoda, N. J . Am. Chem. Soc. 1991,
1
1
13, 9796.
4) (a) Han, L.-B.; Ishihara, K. I.; Kambe, N.; Ogawa, A.; Ryu, I.; Sonoda,
(
N. J . Am. Chem. Soc. 1992, 114, 7591. (b) Han, L.-B.; Ishihara, K. I.; Kambe,
N.; Ogawa, A.; Sonoda, N. Phosphrous Sulfur Silicon Relat. Elem. 1992,
6
7, 243.
(5) Normant, J . F.; Bourgain, M. Teteahedron Lett. 1970, 2659.
6) Tomoda, S.; Takeuchi, Y.; Nomura, Y. Chem. Lett. 1982, 253. We
(7) Zhao, C. Q.; Huang, X. Synth. Commun. 1997, 27, 249.
(8) Typical procedure for telluroacylation: Under N , telluroester (1
2
(
found that cuprous alkynylides could be prepared from cuprous iodide and
terminal alkynes in the presence of triethylamine. The typical procedure
is as follows: Terminal alkyne (2 mmol) was added dropwise to a solution
of cuprous iodide (0.38 g, 2 mmol) and triethylamine (0.42 mL, 3 mmol) in
mmol), phenylethyne (0.11 g, 1 mmol), cuprous iodide (0.09 g, 0.5 mmol),
and triethylamine (0.14 mL, 1 mmol) in 5 mL of anhydrous DMF were
heated at 50-60 °C for 1 h. Trimethylamine hydrochloride was then added
after cooling, and the mixture was heated at 60-70 °C for another 8 h. The
1
0 mL of dimethylformamide with stirring at room temperature. The
4
saturated solution of NH Cl (20 mL) was added after cooling. The precipitate
resulting mixture was stirred for 30 min. Water (20 mL) was added, and
the solid was filtered, washed with water, ethanol, and ether, respectively,
affording a yellow solid of cuprous alkynylide, with 80-93% yields for
different alkynes.
was filtered away and washed with ether. The filtrate was extracted with
ether three times. The combined organic layer was washed with water and
dried over anhydrous magnesium sulfate. The solvent was removed in vacuo,
and the residue was recrystallized from ether.
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Published on Web 06/11/1998