Tellurium in organic synthesis: an approach to the synthesis of (Z,E)-dienic precursors of insect pheromones

Article abstract of DOI:10.1016/j.tetlet.2006.08.005

A simple and straightforward route to (Z,E)-dienic precursors of insect pheromones was developed. The route features a cross-coupling of a (Z,E)-dienic telluride with an alkyl Lipshutz cuprate.

Full text of DOI:10.1016/j.tetlet.2006.08.005

Tetrahedron Letters 47 (2006) 7147–7148
Tellurium in organic synthesis: an approach to the synthesis
of (Z,E)-dienic precursors of insect pheromones
Dennis G. Diego, Rodrigo L. O. R. Cunha and Joao V. Comasseto*
˜
Instituto de Quı´mica, Universidade de Sa˜o Paulo, Av. Prof. Lineu Prestes, 748, Cx.P. 26077, 05599-970 Sa˜o Paulo, Brazil
Received 17 July 2006; revised 31 July 2006; accepted 2 August 2006
Available online 22 August 2006
Abstract—A simple and straightforward route to (Z,E)-dienic precursors of insect pheromones was developed. The route features a
cross-coupling of a (Z,E)-dienic telluride with an alkyl Lipshutz cuprate.
Ó 2006 Elsevier Ltd. All rights reserved.
Several routes for the synthesis of dienic pheromones
have been developed. Some of them involve a stepwise
construction of the (Z,E)-dienic fragment. Others use
multistep synthesis to assembly an enyne, which is then
reduced to the desired (Z,E)-diene.1,2
a common precursor for this class of compounds
(Scheme 2).
The tellurodiene 1 was prepared as described first, by
hydrotelluration of 2 with a mixture of dibutylditelluride
and sodium borohydride in ethanol,11 or by reaction of
2 with lithium butyltellurolate, prepared in situ from
insertion of elemental tellurium into nbutyllithium in
THF, in the presence of ethanol12 (Scheme 3).
Over the past years we have been concerned with the
construction of unsaturated systems using tellurium
chemistry.3 One of the most useful methodologies devel-
oped by us for this purpose consists in the hydrotellura-
tion of alkynes, leading to Z-vinylic tellurides.4 Of
particular interest is the tellurodiene 1, which was al-
ready used in our group in the synthesis of a natural
product.5 The tellurodiene 1 is obtained by hydrotellura-
tion of the commercially available and easily prepared
(E)-pent-2-en-4-yn-1-ol 26 (Scheme 1).
With the tellurodiene 1 in hands, it was transformed into
the corresponding alcoholate 3 by reaction with sodium
hydride in THF at 0 °C. After the addition of sodium
hydride to the solution of 1 in THF, the mixture became
brown and then turned to black. This solution was then
transferred via canula to a solution of a previously pre-
pared magnesium alkylcyanocuprate 4 in THF at room
Keeping in mind the peculiar reactivity of vinylic
tellurides,3 specially their ability to cross-couple with
cuprates,7–10 a retrosynthetic analysis of (Z,E)-dienic
pheromones shows that compound 2 could constitute
telluride-cuprate
TeBu
R
cross-coupling
H
R1
OH
TeBu
allylic
alkylation
1
OH
Scheme 2.
OH
1
2
BuTeLi, EtOH (3 eq.)
THF, reflux, 6 h
(BuTe)2, NaBH4
EtOH, r.t., 3 h
Scheme 1.
1
1
2
75%
75%
*
Corresponding author. Tel.: +55 11 3091 2176; fax: +55 11 3815
5579; e-mail: jvcomass@iq.usp.br
Scheme 3.
0040-4039/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2006.08.005

7148
D. G. Diego et al. / Tetrahedron Letters 47 (2006) 7147–7148
TeBu
1) R2Cu(CN)(MgBr)2 (4, 1.2 eq.)
NaH (1.2 eq.)
THF, 0 oC, 15 min
THF, r.t., 24 h
1
2) Ac2O (5 eq.), 2 h
ONa
3
R
R = Et 5a 81%
nPr 5b 80%
nBu 5c 80%
OAc
5
Scheme 4.
Acknowledgments
OAc
+
ClMg
OTHP
The authors acknowledge the following agencies for
support: CNPq and FAPESP.
6
5a
1) Li2CuCl4
THF, 20 oC
2) AcOH, AcCl
References and notes
OAc
1. Mori, K.; Tashiro, T. Current Org. Synth. 2004, 1, 11.
2. Uenishi, J.; Kawahama, R.; Izaki, Y.; Yonemitsu, O.
Tetrahedron 2000, 56, 3493.
7
Scheme 5.
3. For a recent review see: Zeni, G.; Ludtke, D. S.; Panatieri,
¨
R. B.; Braga, A. L. Chem. Rev. 2006, 106, 1032.
4. Vieira, M. L.; Zinn, F. C.; Comasseto, J. V. J. Brazil.
Chem. Soc. 2001, 12, 586.
5. Marino, J. P.; McClure, M. S.; Holub, D. P.;
Comasseto, J. V.; Tucci, F. C. J. Am. Chem. Soc.
2002, 124, 1664.
6. Brandsma, L.. Preparative Acetylenic Chemistry, 2nd ed.;
Oxford, 1988.
7. Chieffi, A.; Comasseto, J. V. Tetrahedron Lett. 1994, 35,
4063.
temperature and the reaction mixture was stirred at this
temperature for 24 h. After this time, the mixture was
treated with an excess of acetic anhydride and stirred
for 2 h at room temperature. The (Z,E)-dienic acetates
5 were obtained in goods yields (Scheme 4). The acetates
5a–c constitute precursors of the insect sex pheromones
of, respectively, Lobesia botrana,13 Bombyx mori14 and
Malacososma disstria.15
8. Chieffi, A.; Comasseto, J. V. Synlett 1995, 671.
9. Castelani, P.; Comasseto, J. V. J. Brazil. Chem. Soc. 2004,
15, 461.
10. Castelani, P.; Comasseto, J. V. Tetrahedron 2005, 61,
2319.
In this way, in a single operation, the telluride 1 was
transformed into advanced intermediates in the synthe-
sis of three insect sex pheromones.
Allylic acetates react with Grignard reagents under cop-
per species catalysis.16 In this way, treatment of the ace-
tates 5 with the appropriate Grignard reagent in the
presence of a copper catalyst would give the insect sex
pheromones mentioned above. In fact, the acetate 5a
was already transformed into the sex pheromone of
Lobesia botrana 7 by reaction with the appropriate pro-
tected Grignard reagent 6, in the presence of dilithium
tetrachlorocuprate, followed by deprotection and acetyl-
ation (Scheme 5).13
11. Tucci, F. C.; Chieffi, A.; Comasseto, J. V.; Marino, J. P. J.
Org. Chem. 1996, 61, 4975.
12. Zeni, G.; Formiga, H. B.; Comasseto, J. V. Tetrahedron
Lett. 2000, 41, 1311.
13. Cassani, G.; Massardo, P.; Piccardi, P. Tetrahedron Lett.
1980, 21, 3497.
14. Normant, J. F.; Commercon, A.; Villiera, J. Tetrahedron
Lett. 1975, 1465.
15. Stille, J. K.; Simpson, J. H. J. Am. Chem. Soc. 1987, 109,
813.
16. Krause, N.. Modern Organocopper Chemistry; Wiley,
2001.
Further work is underway to apply this methodology in
the synthesis of a whole series of pheromones containing
the (Z,E)-dienic moiety17 in their structures.
17. Mori, K. The Synthesis of Insect Pheromones, 1979–1989.
Total Synthesis of Natural Products; Wiley Interscience,
1992.