β-Functionalized selenides and tellurides by hydrochalcogenation of olefins containing electron-withdrawing groups

Article abstract of DOI:10.1016/S0040-4039(02)00095-3

Olefins conjugated to electron-withdrawing groups (e.g. CHO, RCO, CO₂R, CN) react rapidly with alkylselenols and tellurols generated in situ to give the corresponding β-chalcogeno aldehydes, ketones, esters and nitriles. β-Telluroketones are tr

Full text of DOI:10.1016/S0040-4039(02)00095-3

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 43 (2002) 1625–1628
b-Functionalized selenides and tellurides by hydrochalcogenation
of olefins containing electron-withdrawing groups
Fabiano K. Zinn, Vin´ıcius E. Righi, Silas C. Luque, Henrique B. Formiga† and Joa˜o V. Comasseto*
Instituto de Qu´ımica, Universidade de Sa˜o Paulo, Av. Prof. Lineu Prestes, 748, Cx.P. 26077, 05599-970 Sa˜o Paulo, Brazil
Received 5 December 2001; revised 10 January 2002; accepted 11 January 2002
Abstract—Olefins conjugated to electron-withdrawing groups (e.g. CHO, RCO, CO2R, CN) react rapidly with alkylselenols and
tellurols generated in situ to give the corresponding b-chalcogeno aldehydes, ketones, esters and nitriles. b-Telluroketones are
transformed into b-telluroketals, which are b-lithiocarbonyl synthons. © 2002 Elsevier Science Ltd. All rights reserved.
The hydrotelluration of alkynes is a widely explored
reaction to prepare vinylic tellurides.1 The hydrotellura-
tion of alkenes, on the contrary received little attention
and, to our knowledge, only a brief mention to this
reaction was made in the literature.2 In 1987 Uemura
reported the reaction of a,b-unsaturated esters and
nitriles 1 with a mixture of diphenylditelluride and
sodium borohydride in ethanol to give the correspond-
ing b-phenyltelluroesters and nitriles 2 in 31–71% yield
(Scheme 1).
lenation of olefins containing electron-withdrawing
groups.
Lithium butyltellurolate (3) was prepared by addition
of commercial butyllithium to a suspension of elemen-
tal tellurium in dry tetrahydrofuran under deoxy-
genated nitrogen at room temperature. A yellow
solution was rapidly formed. To this solution was
added 1 equiv. of absolute ethanol and then the olefin
containing an electron-withdrawing group (EWG) 5.
After some time TLC analysis showed that all the
starting material was consumed. Work-up of the reac-
tion mixture led to the 1,4-addition product 6 in good
to excellent yields (Scheme 2, Table 1).4
A limitation of this method is the use of reducing
conditions, which can affect some functionalities
present in the unsaturated substrates. In addition, if
dialkylditellurides are used, the bad smell of these
compounds is also a limiting factor. Recently we cir-
cumvented these problems by generating organotel-
lurols in situ by the reaction of an organolithium with
elemental tellurium in THF followed by addition of a
proton source such as ethanol or water, and then
reacting the in situ formed tellurol with an alkyne.3
The reaction worked well when mono- and disubsti-
tuted olefins were used but failed with trisubstituted
ones (entries 7 and 11, Table 1). This methodology
failed also when 2,3-cyclohexenone was used. Conden-
sation products of the enone were formed instead of the
hydrotelluration product. This problem was solved by
using water (2.5 equiv.) instead of ethanol as the proton
In this communication we describe the application of
this methodology in the hydrotelluration and hydrose-
Scheme 1.
* Corresponding author. E-mail: jvcomass@iq.usp.br
† In memoriam.
Scheme 2.
0040-4039/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(02)00095-3

1626
F. K. Zinn et al. / Tetrahedron Letters 43 (2002) 1625–1628
Table 1.
source. In this case the hydrotelluration reaction led to
the b-butyltellurocyclohexanone in 89% yield (entry 9,
Table 1). The use of water as the proton source was
successful also for the other olefinic substrates. In this
way, it is recommended to use water instead of ethanol
to generate the tellurol.
The above described methodology was successfully
used to prepare also b-seleno carbonyl compounds 7 in
good yields (Scheme 3, entries 15 and 16, Table 1).
Scheme 3.

F. K. Zinn et al. / Tetrahedron Letters 43 (2002) 1625–1628
1627
Scheme 4.
Scheme 5.
This method generates alkylselenols in situ avoiding the
isolation of selenols, which are very bad smelling com-
pounds. The most synthetically useful application of
organotellurides is their transformation into reactive
organometallics, such as organolithium, magnesium, zinc
and copper species.5 Some time ago Sonoda and co-
workers reported the transformation of b-telluroketals 8
into b-lithioketals 9 by reaction of 8 with n-butyllithium,
what transforms these compounds into b-lithiocarbonyl
synthons 106 (Scheme 4).
Comasseto, J. V.; Barrientos-Astigarraga, R. E. Aldrichim.
Acta 2000, 33, 66.
2. Ohe, K.; Takahashi, H.; Uemura, S.; Sugita, N. Nippon
Kagaku Kaishi 1987, 1469.
3. (a) Zeni, G.; Formiga, H. B.; Comasseto, J. V. Tetrahedron
Lett. 2000, 41, 1311; (b) An intramolecular version of this
reaction was developed by Sachida, who prepared several
tellurium heterocycles by this method. For a review, see:
Sachida, H. Rev. Heteroatom. Chem. 2000, 22, 59.
4. Typical procedure for the hydrotelluration of olefins: In a
two-necked 50 mL flask under nitrogen and magnetic
stirring was placed elemental tellurium (0.511 g, 4 mmol) in
dry THF (5 mL). To this suspension at room temperature
was added n-butyllithium (3.08 mL of a 1.3 M solution in
hexane, 4 mmol). A yellow solution was formed. To this
solution was added 1 equiv. of ethyl alcohol. Then ethyl
acrylate (0.44 mL, 4 mmol) was added at 0°C. The mixture
was allowed to reach the room temperature and maintained
under stirring for 1 h, then it was diluted with ethyl acetate
(5 mL). The organic phase was washed with NH4Cl (3×15
mL) solution and brine (3×15 mL) and then dried with
magnesium sulfate and the solvent was evaporated. The
residue was purified by silica gel column chromatography
eluting with hexane. Yield of 3-butyltellanylpropionic acid
In view of this synthetic application of b-telluroketals 8
we transformed 11 into 8. The transformation occurs in
good yield by reacting the b-telluroketones (entries 8 and
9, Table 1) with ethylene glycol in dry tetrahydrofuran
in the presence of Amberlyst® 157 (Scheme 5).
In view of the easy access to enones, the reaction
sequence described by us is a very convenient method to
prepare b-telluroketals 8.
In conclusion, we developed a practical method to
prepare b-functionalized tellurides and selenides. The
b-tellurocarbonyl compounds were transformed into
b-telluroketals, which are b-lithiocarbonyl synthons.
1
ethyl ester (entry 1, Table 1): 0.49 g (96%). H NMR (300
MHz, CDCl3, ppm) l 0.92 (t, J=7.4 Hz, 3 H); 1.27 (t, J=7.1
Hz, 3 H); 1.38 (sext., J=7.4 Hz, 2 H); 1.74 (quint., J=7.4
Hz, 2 H); 2.68 (t, J=7.4 Hz, 2 H); 2.83 (A2B2, Dw/J=1.5
Hz, J=1.1 Hz, 4 H); 4.15 (q, J=7.1 Hz, 2 H). 13C NMR
(75 MHz, CDCl3, ppm): l 173.15; 60.65; 37.47; 34.33; 25.09;
14.26; 13.41; 3.32; −5.78. 125Te NMR (157 MHzm CDCl3,
ppm, Ph2Te2 internal standard): l 279.19. LRMS m/z
(relative intensity, %): 288 (35); 286 (30, M+); 231 (28); 229
(26); 186 (29); 184 (28); 57 (94); 55 (100). IR (cm−1): 2958;
2928; 2870; 1735. Anal. calcd: C, 37.82; H, 6.35. Found: C,
37.69; H, 6.35%.
Acknowledgements
The authors would like to thank CNPq and FAPESP for
their support.
References
1. For recent reviews, see: (a) Vieira, M. L.; Zinn, F. K.;
Comasseto, J. V. J. Braz. Chem. Soc. 2001, 12, 586; (b)
5. For recent reviews, see: Ref. 1.

1628
F. K. Zinn et al. / Tetrahedron Letters 43 (2002) 1625–1628
6. Inoue, T.; Atarashi, Y.; Kambe, N.; Ogawa, A.; Sonoda,
N. Synlett 1995, 209.
solvent was evaporated. The residue was purified by
column chromatography on neutral aluminum oxide elut-
ing with hexane/ethyl acetate (10: 1). Yield of 2-(2-
butyltellanylethyl)-2-methyl-[1,3]-dioxolane (8a):6 0.92 g
(3.04 mmol, 78%). 1H NMR (300 MHz, CDCl3, ppm) l
0.92 (t, J=7.3 Hz, 3 H); 1.32 (s, 3 H); 1.38 (sext., J=7.3
Hz, 2 H); 1.72 (qt, J=7.3 Hz, 2 H); 2.10–2.16 (m, 2 H);
2.60–2.66 (m, 4 H); 3.95 (m, 4 H). 13C NMR (75 MHz,
CDCl3, ppm): l 110.2; 64.6; 42.1; 34.1; 24.9; 23.4; 13.3;
2.6; −5.6. LRMS m/z (relative intensity, %): 302 (3, M+);
99 (4); 87 (100); 55 (15); 43 (58). IR (cm−1): 2979; 2958;
2927; 2874; 1457; 1378; 1246; 1212; 944.
7. Typical procedure for the transformation of a i-telluroke-
tone into a i-telluroketal: In a two-necked 50 mL flask
under nitrogen and magnetic stirring was placed butyl-(2)-
butanoyl telluride (11a, 1 g, 3.9 mmol), Amberlyst® 15 (0.2
g) and ethylene glycol (0.62 g, 10 mmol) in dry THF (15
mL). This mixture was allowed to react under reflux for 1
h and then it was diluted with NH4Cl (5 mL) and ethyl
acetate (5 mL). The organic phase was washed with
NH4Cl (3×15 mL) solution and brine (3×15 mL). The
organic phase was dried with magnesium sulfate and the