COMMUNICATIONS
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Figure 3. Current ± voltage relationships for single channels of
1 in
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The present work reports on the synthesis and functional
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solid-phase NMR is currently under investigation and will be
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Experimental Section
Planar lipid membranes were prepared by painting a solution of soybean
lecithin (45% Avanti Polar Lipids) in n-decane (25 mgmL 1) over a cuvette
aperture with a diameter of 0.15 mm.[1c] The membrane surface was 0.01 to
0.02 mm2 assuming a specific membrane capacity of 0.4 mFcm 2. All
experiments were performed at ambient temperature. The electrolyte
solutions with a concentration of 1m each were unbuffered. The probes,
dissolved in methanol, were added to the trans side, to give a final
concentration of 0.01 ± 0.03mm. Current detection and recording was
performed using a patch-clamp amplifier Axopatch 200, a DigiData A/D
converter, and the pClamp 6 software (Axon Instruments). The aquisition
frequency was 5 kHz. The data were filtered with an analogue filter at
100 Hz for further analysis.
Simple Synthesis of Tetra-Acceptor-Substituted
Alkenes by the Formal Dehydrodimerization of
Malonates**
Torsten Linker* and Ursula Linker
Dedicated to Professor Bernd Giese
on the occasion of his 60th birthday
Acceptor-substituted alkenes are important precursors for
Diels ± Alder reactions, Michael additions, or polymeriza-
tions. Due to their electronic properties, ethylenetetracarbox-
ylates exhibit an especially high reactivity, but are difficult to
prepare. Traditional syntheses start from halomalonates and
sodium or mesoxalic acid,[1] whereas modern methods by the
dimerization of malonates require an excess of oxidant or the
use of expensive azo compounds.[2] Furthermore, disadvan-
tages of all methodologies are the moderate yields. Herein we
describe a simple new access to tetra-acceptor-substituted
alkenes by the formal dehydrodimerization of malonates in
only two steps. The synthesis is characterized by cheap
reagents and high yields.
Received: October 7, 1999 [Z14124]
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432.
[3] Recent contributions: a) T. D. Clark, L. K. Buchler, M. R. Ghadiri, J.
Am. Chem. Soc. 1998, 120, 651 ± 656; b) T. M. Fyles, D. Loock, X.
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35, 757 ± 759.
During the course of our investigations on transition metal
mediated radical reactions,[3] we succeeded in the addition of
dimethyl malonate (1a) to various alkenes. To further
improve the yields and due to the mild conditions, we became
[*] Prof. Dr. T. Linker, Dr. U. Linker
Institut für Organische Chemie der Universität
Pfaffenwaldring 55, 70569 Stuttgart (Germany)
Fax : ( 49)711-685-4269
[**] This work was supported by the Fonds der Chemischen Industrie and
the Deutsche Forschungsgemeinschaft (SFB 347 ªSelective Reactions
of Metal-Activated Moleculesº).
[4] U. Koert, M. Stein, K. Harms, Angew. Chem. 1994, 106, 1238 ± 1240;
Angew. Chem. Int. Ed. Engl. 1994, 33, 1180 ± 1182.
902
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