Cyclooctatetraene made easy

Article abstract of DOI:10.1016/j.tetlet.2004.03.064

Cyclooctatetraene, C₈H₈, has been made readily available from 1,5-cyclooctadiene in 65% yield without the need of using hazardous or toxic reagents by the straightforward oxidation of the intermediate [Li(tmeda)]₂C₈

Full text of DOI:10.1016/j.tetlet.2004.03.064

Tetrahedron
Letters
Tetrahedron Letters 45 (2004) 3583–3584
Cyclooctatetraene made easy
Jochen Gottfriedsen, Alesia Miloslavina and Frank T. Edelmann*
Chemisches Institut der Otto-von-Guericke-Universit €a t Magdeburg, Universit €a tsplatz 2, D-39106 Magdeburg, Germany
Received 9 February 2004; accepted 10 March 2004
8 8
Abstract—Cyclooctatetraene, C H , has been made readily available from 1,5-cyclooctadiene in 65% yield without the need of using
0
0
hazardous or toxic reagents by the straightforward oxidation of the intermediate [Li(tmeda)]
methylethylenediamine) with di-tert-butylperoxide.
2
C
8
H
8
(3, tmeda ¼ N,N,N ,N -tetra-
ꢀ
2004 Elsevier Ltd. All rights reserved.
1
Since its discovery by Willst €a tter in 1911, cycloocta-
tetraene, C (1), has never lost its fascination and
purpose of making cyclooctatetraene on a preparative
scale, as the starting material K is highly explosive
and therefore difficult to handle. In the case of the I
8
H
8
2 8 8
C H
remains a highly valuable intermediate in organic syn-
thesis as well as a useful sterically demanding ligand in
organometallic chemistry. The classical Reppe syn-
thesis of cyclooctatetraene involves tetramerization of
acetylene under high pressure in the presence of nickel
2
oxidation the isolated yield of 1 is only 22%. Thus there
is a strong demand for a simple and straightforward
cyclooctatetraene synthesis employing cheap starting
materials and without the need of using hazardous and/
or toxic reagents. We report here that di-tert-butylper-
oxide is the reagent of choice for cleanly converting 3
into cyclooctatetraene. The stable di-tert-butylperoxide
is commercially available and its handling does not
require any special safety precautions.
2;3
4
catalysts. However, the use of flammable and poten-
tially explosive acetylene under pressure makes this
method unsuitable for laboratory use. In addition, since
industrial production has been discontinued, cyclo-
octatetraene has become a very expensive material in
recent years.
[
diene (2) in virtually quantitative yield following the
procedure given by Cloke et al. There is no need to
Li(tmeda)] C H (3) was prepared from 1,5-cycloocta-
2 8 8
Quite surprisingly, there is also a significant lack of
straightforward laboratory methods for synthesizing 1.
Several attempts have been reported to convert the
cheap and readily available 1,5-cyclooctadiene (2) via
5
isolate 3 as a solid material. When di-tert-butylperoxide
was slowly added to a freshly prepared suspension of 3
in n-pentane a vigorous reaction was observed, which
required cooling of the reaction mixture during the
peroxide addition. Further heating for 4 h produced a
yellow solution of cyclooctatetraene along with a white
2ꢀ
the C
8
H
8
dianion into cyclooctatetraene. According to
Cloke and co-workers 2 can easily be metalated upon
treatment with n-butyllithium in the presence of tmeda
2 8 8
to afford the intermediate [Li(tmeda)] C H (3) in high
5
t
yield. In a recently reported cyclooctatetraene synthesis
mercury dichloride has been employed as an oxidizing
precipitate of LiO Bu. Standard hydrolytic work-up
afforded pure cyclooctatetraene 1 in 65% yield (bp 142–
143 ꢁC). The overall one-pot reaction is illustrated in
Scheme 1.
2
ꢀ
6
agent for the conversion C
8
H
yield of 1 is acceptable (45%), but a major disadvantage
8
fi C
8 8
H . The isolated
of this method is the use of large amounts of highly toxic
HgCl
reports the oxidation of K
or iodine. This method too is unsatisfactory for the
2
. A more recent paper by Simons and Lagowski
with either dry oxygen
The method reported here provides an easy and
straightforward access to preparative amounts of
cyclooctatetraene. The new method combines several
synthetic advantages: it uses cheap starting materials
and can be carried out as a one-pot reaction. It is also
clean as the oxidizing agent di-tert-butylperoxide yields
only tert-butanol as a by-product, and there is no need
2
8 8
C H
7
Keywords: Cyclooctatetraene; Cyclooctadiene; di-tert-Butylperoxide.
*
Corresponding author. Tel.: +49-391-6718327; fax: +49-391-67129-
3; e-mail: frank.edelmann@vst.uni-magdeburg.de
of using hazardous (such as explosive K
toxic (such as HgCl ) reagents. Thus it makes laboratory
2 8 8
C H ) and/or
3
2
0
040-4039/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2004.03.064

3584
J. Gottfriedsen et al. / Tetrahedron Letters 45 (2004) 3583–3584
4
and dried over anhydrous MgSO . Distillation under
Me N
NMe2
2
normal pressure afforded 24.85 g 1 (bp 142–143 ꢁC)
whose spectroscopic and analytical data were in excel-
lent agreement with the published data.
2
n-BuLi
Li
tmeda
2
Li
Me N
NMe2
2
t
t
Acknowledgements
BuOOBu
3
t
This work was generously supported by the Otto-von-
Guericke-Universit €a t Magdeburg and the German
Academic Exchange Service DAAD (IAESTE fellow-
ship for A. Miloslavina).
-
-
2 LiO Bu
2 tmeda
1
Scheme 1. Synthesis of cyclooctatetraene (1).
quantities of cyclooctatetraene readily available in a safe
and straightforward manner.
References and notes
1
2
. Willst €a tter, R.; Waser, E. Chem. Ber. 1911, 44, 3423.
. Fray, G. I.; Saxton, R. G. The Chemistry of Cyclooctatetr-
aene and its Derivatives; Cambridge University: Cambridge,
Experimental procedure
1
978.
3
. Comprehensive Organometallic Chemistry; 2nd ed.; Abel, E.
W., Stone, F. G. A., Wilkinson, G., Eds.; Pergamon:
Oxford, 1996; Vol. 4.
To a stirred solution of 1,5-cyclooctadiene (45 mL,
0
.367 mol) in n-pentane (370 mL) was added dropwise
n-butyllithium (153 mL of a 1.6 M solution in n-hexane)
followed by slow addition of tmeda (37 mL), and stirring
was continued for 24 h. Di-tert-butylperoxide (67.4 mL,
4. For example, British Patent No. 706629 and U.S. Patents
No. 2,579,106, 2,613,231, and 2,903,491.
5
. Burton, N. C.; Cloke, F. G. N.; Joseph, S. C. P.;
Karamallakis, H.; Sameh, A. A. J. Organomet. Chem.
0
.796 mol) was added dropwise over 1 h at 0 ꢁC. After
1
993, 462, 39; cf. also: Gausing, W.; Wilke, G. Angew.
Chem. 1978, 90, 380; Angew. Chem., Int. Ed. Engl. 1978, 17,
71.
. Wetzel, T. G.; Dehnen, S.; Roesky, P. W. Organometallics
999, 18, 3835.
stirring at room temperature for another hour, the
resulting suspension was stirred at reflux temperature
for 4 h. The mixture was added to 300 mL of ice water
and diluted with n-pentane (200 mL). The organic layer
was washed thoroughly with diluted acetic acid (1%,
3
6
1
7. Simons, L. H.; Lagowski, J. J. Tetrahedron Lett. 2002, 43,
1771.
6
· 150 mL), saturated NaHCO solution (3 · 150 mL),
3