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Novel One-Step Synthesis of Oxocyclopentanecarboxylates by Electrochemical Reduction of Cinnamic Acid Esters.

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Scheme 1.
= I3C.
When the experiment was carried out using the [2,4I3Cz]labeled isotopomer l a the following results were obtained :
as expected, m / z 356 is quantitatively shifted to m / z 358,
and its MWMS spectrum contains only a single signal at
m / z 179 ( e4a) after isotopic correction[41. The following
conclusion can be drawn from this: Decarbonylation of 1
by electron impact ionization leads to an intermediate,
which must be a derivative of ionized cyclobutadiene 2.
Generation of a tetraphenyltetrahedrane radical cation 3,
whose existence was postulated previouslyf5I, is completely
inconsistent with the data obtained for l a . If the tetrahedrane intermediate 3a were really involved o r a carbon
scrambling of the C, moiety in the [M-CO]@' ion obtained from l a were to occur, then the distribution pattern
shown in Scheme 1 should be observed in the formation of
the ionized diphenylacetylene isotopomers (4, 4a, and
4b). This does not occur. The results are only compatible
with route a and certainly exclude route b and isomerization c.
example, exclusively 2a was obtained in 74-76% yield
(Table 2[,') from l a in acetonitrile or dimethylformamide
(DMF), whereas electrochemical reduction of l a in methanol gave dimethyl 3,4-diphenyladipate 3a as the sole productf3]in 75% yield.
C,H5-C H-CH,-C
Novel One-Step Synthesis of
Oxocyclopentanecarboxylates by
Electrochemical Reduction of Cinnamic Acid Esters
By Ikuzo Nishiguchi* and Tsuneaki Hirashima
The electrochemical reduction of a$-unsaturated esters
in aqueous solution usually gives the corresponding hydrodimers, i.e. adipic acid derivatives, as the main products['C.21.We have now found that oxocyclopentanecarboxylates 2 are formed in moderate to good yields by electrochemical reduction of cinnamate derivatives 1 . A remarkable solvent effect was observed in this dimerization. For
[*] Dr. 1. Nishiguchi, Dr. T. Hirashima
Osaka Municipal Technical Research Institute
1-6-50 Morinomiya, Jyoto-ku, Osaka 536 (Japan)
0 Verlag Chemie GrnbH, 6940 Weinheim, 1983
Table 2. Electrochemical reduction of l a - l h to Za-2h [a].
Received: September 21, 1982 [Z 153 IE]
German version: Angew. Chem. 95 (1983) 59
[I] a) H. Bock, B. Roth, G. Maier, Angew. Chem. 92 (1980) 213; Angew.
Chem. In/. Ed. Engl. 19 (1980) 209; b) R. Wolfschiitz, H. Schwarz, unpublished results; c) For the photo induced generation of the tetramethylcyciobutadiene radical cation see: Q. B. Broxterman, H. Hogeveen, D. M.
Kok, Tetrahedron Lett. 22 (1981) 173.
[Z] K. Levsen, H. Schwarz., Angew. Chern. 88 (1976) 589; Angew. Chem. In/.
Ed. Engl. I5 (1976) 509.
131 H. Schwarz, Nachr. Chern. Tech. Lab. 29 (1981) 687.
[4] A weak signal at m / z 180 (6%) can be attributed to incomplete ["C2]-labeling of l a . 38% of 1 is present as the ['3C,]-isotopomer, and the natural
["CI-abundance in the [M-COIQQ ion of this species gives rise to the
formation of m / z 180. A signal at m / z 178 is not observed in the MS/MS
spectrum of m / z 358.
IS] M. M. Bursey, T. A. Elwood, Org. Mass Specrrom. I (1968) 531.
- Wbo
Yield [Yo] [b]
M . p . ["C]
[a] Cell, which is fitted with a stirring device, consists of a ceramic diaphragm, Cu cathode, Pt anode, D M F as solvent, tetraethylammonium p-toluenesulfonate as supporting electrolyte, at 10- 15 "C, cathode potential
- 1.9 to -2.2 V us. SCE, 4.0 F/mol. [b] Isolated yield. [c] 2-Pyridyl.
Information on the reaction pathway was obtained by
electrochemically reducing l h and 3a (molar ratio 1 : 1)
under similar conditions as in Table 2. As a result, exclusively the dimeric cyclization product 2h was formed in
74% yield, and 3a was recovered quantitatively: 2a was
not detected. This result clearly shows that the reaction
proceeds via a dimeric anionic intermediate such as 4ls1,
which yields the cyclization product 2 or the simple hydrodimer 3 depending upon the proton-donating ability of
the solvent: this also excludes the possibility of Dieckmann condensation of 3 to 2 under the reaction conditions.
Received: March 9, 1981 [Z 406 IE]
revised: October 22, 1982
German version: Angew. Chern. 95 (1983) 61
The complete manuscript of this communication appears in:
Angew. Chem. Suppl. 1983. 70-74
[I] c) N. L. Weinberg: Technique of Electroorganic Synthesis, Part 11, Wiley,
New York 1974, pp. 87-136, and references cited therein.
[2] M. M. Baizer, J. M. Anderson, J . Electrochem. Soc. I l l (1964) 223.
0570-0833/83/0101-0052 .$ 02.50/0
Angew. Chem. I n / . Ed. Engl. 22 (1983) No. I
131 a) E. L. Totton, R. C. Freeman, T. L. Yarboro, J . Org. Chem. 26 (1961)
343; b) J. P. Petrovich, M. M. Bailer, M. R. Ort, J . Electrochem. SOC.116
(1969) 749.
[4] All the products were isolated and identified by spectroscopic and/or elemental analyses.
[ S ] M. M. Baizer, J. P. Petrovich, D. A. Tyssee, J . Electrochem. SOC. 117
(1970) 173.
r=, onoo-
By Mordecai Rabinovitz*, Henry Selig, and Jaacov Levy
The intercalation of metals and salts into the graphite
lattice markedly changes the chemical properties and behavior of the intercalated speciesr',21.For example, the
reaction of potassium intercalated in graphite with H2 is
very fast, even at room temperature, whereas metallic potassium reacts very sluggishly with H2 below 200 0C[31.We
report here the preparation of a series of novel Hglgraphite compounds, which should be interesting electrode materials or reagents. Until now, intercalation compounds of
Hg/graphite have only been prepared in the form of ternary compounds with alkali metals[41.The synthesis of binary compounds, or even nonstoichiometric mixtures of
graphite/Hg has hitherto been unsuccessful.
The reaction of C& with an equivalent amount of Hg
yields C8KHgL4];it has also been reported that graphite
and KHg afford C4KHg. We report that the reaction of
C8K with varying amounts of Hg allows the preparation of
a series of compounds, of general formula C8KHg,. C8K
was prepared by evaporating the stoichiometric amount of
potassium over graphite, under an inert gas atmosphere at
200 "C. The potassium intercalate so formed was allowed
to cool to room temperature and the calculated amount of
mercury was added. The mixture was heated to 80 "C for
10 min, and then cooled to room temperature. When the
C8KHg, was hydrolyzed with a protic solvent, C8Hg, was
obtained together with metallic Hg.
+ Hg<,-,, + KOR + 0.5Hz
Hg added initially [mag
Fig. I . Plot of amount of Hg in CxHg, after hydrolysis of CaKHg, against the
amount of Hg originally present.
Thermogravimetric analyses (TGA) of C8Hg, indicate
that the Hg is lost completely at 400°C. This suggested
that the Hg is intercalated as Hg'. The residual material
after TGA exhibits the interlayer spacing of pure graphite.
Received: August 10, 1981 [Z 410 IE]
revised: October 28, 1982
German version: Angew. Chem. 95 (1982) 45
[I] A. McKillop, D. W. Young, Synthesis 1979, 401, 481.
[2] H. Selig, L. Ebert, Adu. Inorg. Chem. Radiochem. 23 (1980) 281.
131 H. Remy, Treotise on inorganic Chemistry, Vol. 1, Elsevier, New York,
1956, p. 156ff.
[4] P. Lagrange, M. El Makrini, D. Guerard, A. Herold, Synth. Metals 2
(1980) 19, 197.
1-Alkynylamines by Electrophilic Amination
By Gernot Boche*, Michael Bernheim, and
Manfred Niessner
The direct synthesis of 1-alkynylamines, e . g . 3 , from 1alkynes should be possible by electrophilic amination of
the readily accessible acetylides 1 with 2.
M. Rabinovitz, Prof. H. Selig, J. Levy
Department of Organic Chemistry,
The Hebrew University of Jerusalem
Jerusalem 91904 (Israel)
M = metal(derivative); X =anionic leaving group
Actually, the first directed synthesis of 1-alkynylamines
was carried out according to this scheme in 196Or1];however, the yields were so unsatisfactory (1.7%) that alternative
synthetic routes had to be developed[21.
This work was supported by the Israel Commision for Basic Research of
the Israel Academy of Science and Humanities.
la-MgBr : M = MgBr
p] Prof.
Angew. Chem int. Ed. Engl. 22 (1983) No. I
The formation of C4KHg14'has previously seen assumed to
occur in two stages: firstly, the potassium intercalates with
graphite to form C8K, which then reacts with Hg to form
C4KHg, in which the Hg atoms form layers between two
layers of K atoms. However, although we started with
C8K, we failed to obtain C,KHg; instead, the X-ray spectrum was *identical with that reported for C8KHgC4]
(0=10.15 A). This is plausible if one takes into account
that C4KHg is unstable in the presence of KHg, and disproportionates to CsK, C8KHg and Hg. In all the reactions
of C8K with Hg, even in presence of a large excess of Hg,
blue C8KHg was always formed, which then reacts further.
Investigation of the relationship between the initial
amount of Hg present and the amount retained in the
graphite after hydrolysis gave the following results : Molar
ratios of K : Hg from 1 : 1 to 1 :22.5 resulted in complete
reaction of mercury with C8K, and formation of a gray-metallic powder. The results shown in Figure 1 indicate a retention curve that asymptotically approaches 0.120 mol
Incorporation of Mercury into Graphite via
K/Hg Intercalation Compounds**
.Hg; this corresponds to a stoichiometric formula of CsHg,.
All the C,KHg, (x 1) and C8Hg, compounds obtained
strongly absorb X-ray radiation. This could indicate that
Hg atoms are situated randomly between the carbon
2a: X=CH3S03
28 X = (C6H5)2P0,
Prof. Dr. G. Boche, Dr. M. Bernheim, M. Niessner
Fachbereich Chemie der Universitat
Hans-Meerwein-Strasse, D-3550Marburg (Germany)
0 Verlog Chemie GmbH, 6940 Weinherm, 1983
0570-0833/83/0101-0053 $ 02.50/0
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acid, step, synthesis, one, reduction, esters, cinnamic, oxocyclopentanecarboxylates, novem, electrochemically
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