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Bicyclo[4 2 0]octa-2 4 7-triene.

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The relative and absolute configurations of the three centers
of asymmetry at C-10, C-5, and C-6 of secalonic acid A
shown in ( 3 ) were established as follows: The methylsuccinic acid formed by ozonolysis of secalonic acid A is
dextrorotatory and has the (R)-configuration. It therefore
follows that the center of asymmetry at C-6 of this secalonic
acid - which carries the methyl group - has the absolute
configuration shown in ( 3 ) . Since the proton on C-5 in ( 3 )
has a doublet at T = 4.36 with J = 9 cps in its N M R spectrum
in pyridine, it is in trans-diaxial orientation relative to the
methine proton on C-6. This proves that the hydroxy group
is trans-diequatorial relative to the methyl group. The configuration of the methoxycarbonyl group follows from the
mass spectrum and the optical rotatory dispersion of secalonic
acids A and B. The opposite Cotton effect curves [5a] with
unusually high peak values for secalonic acid A [.*I& =
133000 ") and secalonic acid B ([cr]:,
= -1 15 000 ") in chloroform show [6] that the two diastereomers differ in their
configuration at one ring linkage, namely at the angular
methoxycarbonyl group. In secalonic acid A (3), the methoxycarbonyl group must be in the less stable position, viz. cisquasiaxial relative to the neighboring hydroxy group, because it is split off more readily in mass spectroscopy [7] (the
M-COOCH3 fragment from ( 3 ) is 2.7 times more intense
relative to the molecular peak than that from secalonic acid
B).
A buffered solution of the enzyme is applied to the substance
spot and covered with paraffined film (Parafilm@).The degradation products are separated by thin-layer chromatography, compared with known compounds and estimated
quantitatively after elution. The monophosphates can be
degraded further to cytidine, orthophosphate and glucose if,
after pretreatment with phosphodiesterase, a solution of
prostate phosphomonoesterase is added to the substance spot:
cytidine 5'-monophosphate 4- glucose 1-phosphate
prostate phosphomonoesterase
----f
cytidine
pH 5-6, 60 min, 23OC.
+
2 H ~ P O I t glucose
Suitable substrates for the phosphodiesterase reaction are, in
addition to nucleotide sugars, other diesters of pyrophosphoric acid, e.g. diphosphopyridine nucleotide as well as
oligonucleotides with a free terminal 3'-hydroxy group.
Oligonucleotides with a free, terminal 5'-hydroxy group may
be degraded with spleen phosphodiesterase, and nucleoside
2',3'-cyclophosphates with ribonuclease on ion-exchange
layers. The layer has no influence on the specificity of the
enzymes investigated.
The method is suitable not only for the analysis of traces of
nucleotides (quantities < 10-9 mole), but also as a sensitive
detection procedure in enzyme fractionations.
Received, March 19th. 1964
[Z 7101546 1El
German version: Angew. Chem. 76, 438 (1964)
Received, March 20th, 1964
[Z 700/525 IE]
German version: Angew. Chem. 76, 494 (1964)
[ I ] Communication No. VII on Ergot Pigments. - Communication No. VI: B . Franck and E . M. Gottschalk, Angew. Chem.
76, 438 (1964); Angew. Chem. internat. Edit. 3, 441 (1964).
[2] B. Franck, 0. W . Thiele, and T.Reschke, Chem. Ber. 95, 1328
(1962).
[3] B. Franck and G. Baumann, Chem. Ber. 96, 3209 (1963).
[4] J. W. Apsimon, A . J . Corran, N . G.Creasy, W. Marlow, W . B .
Whalkv, and K . Y . Sim, Proc. chern. SOC.(London) 2963, 313.
[5] Stable reaction products which are epimeric at C-9, as discussed by W. B. Wha//ey et al. [4], cannot therefore exist.
[5a] Measured by Prof. S. Shibata, Tokyo.
[6] See C. Djerassi: Optical Rotatory Dispersion. McGraw-Hill,
New York 1960, p. 64; H . G . Leemann and S . Fabbri, Helv. chim.
Acta 42, 2696 (1959).
[7] See K . Biemann: Mass Spectrometry. McGraw-Hill, New
York 1962, p. 144.
[*] Address: Massachusetts General Hospital, Boston 02 I14
(USA.).
[ I ] K . Randerath, Angew. Chem. 74, 780 (1962); Angew. Chem.
internat. Edit. I , 553 (1962); G. Weimann and K . Randerath,
Experientia 19, 49 (1963); K . Randerath, Biochim. biophysica
Acta 61, 852 (1962).
Enzymatic Reactions on Ion-Exchange
Thin-Layer Plates
Huisgen and Mirtzsch [ I ] recently presented convincing
kinetic evidence for the existence of valence tautomerism
between cyclooctatetraene ( 3 ) and bicyclo[4,2,0]octa-2,4,7triene (2). We have now shown that bicyclo[4,2,0]octa-2,4,7triene is produced in good yield when 7,8-dibromobicyclo[4.2.0]-octa-2,4-diene ("cyclooctatetraene dibromide") ( I )
[2] is dehalogenated with disodium phenanthrene in dimethyl
ether at -78 "C [3]. The purest sample of (2) prepared so far
of the bicyclic compound; the impurity was
contained 95
solely (31, which was obviously produced during the workup (distillation at -20 "C) [4].
By Dr. K. Randerath and Dr. Erika Randerath
John Collins Warren Laboratories, Huntington Memorial
Hospital of Harvard University
and
Biochemical Research Department, Massachusetts General
Hospital and Harvard Medical School [*]
Mono- and oligonucleotides may be separated by anionexchange thin-layer chromatography on cellulose impregnated
with polyethyleneimine [l]. We found that enzymatic reactions may be performed directly on the ion-exchange layer.
As an example, we quote the degradation of cytidine diphosphate glucose ( 1 ) to cytidine 5'-monophosphate and
glucose 1-phosphate.
snake-venom
phosphodiesterase
1
cytidine 5' -monophosphate
+
442
pH 7.8
4 5 - 6 0 min, 23°C.
glucose 1-phosphate
Bicyclo[4,2,0]octa-2,4,7-triene
By Prof. Dr. Emanuel Vogel, Dr. H. Kiefer, and
Dr. W. R. Roth
Institut fur Organische Chemie
der Universitlt Koln (Germany)
Dedicated to Prof. H. Meerwein on the occnsion cf his
85th birthday
(1)
(2)
(3)
The chemical evidence for the structure (2) is based on its
catalytic hydrogenation to bicyclo[4,2,0]octane together with
its ready isomerization to I-?). Compound (2) reacts with
maleic anhydride at 0 ° C to give the known adduct of (3).
Bromination of (2) gives mainly tetrabromides [ 5 ] . The
structure (2) is in complete agreement with the spectroscopic
data. The N M R spectrum shows the expected signals from
the four olefinic protons on the six-membered ring (multiplet centered at 4.37 T), the two protons on the double bond
in the four-membered ring (singlet at 4.12 T), and the two
aliphatic, doubly allylic protons (symmetrical multiplet
centered at 6.68 7 ) . The presence of the cyclobutene ring is
Angew. Chem. internat. Edit.
I
Vol. 3 (1964)
1 No. 6
further deduced from the characteristic =C-H and -C=Cstretching vibrations (at 3112 and 1552 cm-1 respectively) in
the infrared spectrum determined at -20 "C [6]. The ultraviolet
maxima at 273 m y (E = 3100) and 277 mi* (E = 3000) correspond t o those of other cyclohexadienes fused onto threeand fsur-membered rings [7].
The activation parameters, Ea = 18.7 & 0.8 kcal/mole and
A = 9.1 x 10" sec-I, for the rearrangement of bicyclo[4,2,0]octa-2,4,7-triene (2) t o cyclooctatetraene (3), were derived
by mesns of the Arrhenius equation from the rate constants
determined between 0 and --20 OC (5 " C intervals) by N M R
spectroscopy. The half-life of (2) in this rearrangement at
0 "C is 14 min. We intend t o determine the enthalpy of the
rearrangement in order t o obtain an independent estimate
of the equilibrium cmcentration of the bicyclic isomer.
Reczived, March 23rd, 1964
[Z 701/531 IE]
German version: Angew. Chem. 76, 432 (1964)
~
[I] According to R . Huisgen and F. Mietzsch, Angew. Chem. 76,
36 (1964); Angew. Chem. internat. Edit. 3, 83 (1964), the equilibrium concentration of (2) is o f the order of 0.01 O h .
[2] Attempts to convert (I) into (2) by dehalogenation with NaI
are described by R. E. Benson and T. L. Cairns, J. Amer. chem.
SOC.72, 5355 (1950).
[3] Cf. N . D . Scott, J. F. Walker, and V . L . Hansley, J. Amer.
chem. SOC.58, 2442 (1936); H . Giisten and L . Horner, Angew.
Chem. 74,586 (1962); Angew. Chem. internat. Edit. I, 455 (1962).
[4] According to E. Migirdicyan and S . Leach, Bull. SOC.Chim.
Belges 71, 845 (1962), and G . J . Fonken, Chem. and Ind. 1963,
1625, low-temperature ultraviolet irradiation o f (3) also gives
rise to (21, but it could not be isolated.
[5] Cf. V . Georgian, G. Georgian, and A . V . Robertson, Tetrahedrm 19, 1219 (1963); C. D . Nenitzescu et al., Chem. Ber. 97,
372 ( I 964).
[6] Determined by W . Liiltkr and A . de Meijere.
[7] A. Eschenmoser et al., Helv. chim. Acta 46, 2893 (1963),
where further references are given.
Proof of a Norcaradiene-Cycloheptatriene
Valence Tautomerism by NMR Spectroscopy
By Prof. Dr. Emanuel Vogel, cand. chem. D. Wendisch and
Dr. W. R. Roth
Institut fur Organische Chemie
der Universitat Koln (Germany)
Dedicated to PrDJ H . Meerwein on the occasion of hi&
85th birthday
The height of the energy barrier separating norcaradiene and
cycloheptatriene is unknown and the assumption of a valence
tautomerism between these two isomers is thus hypothetical
[I]. In the case of benzonorcaradiene, the energy barrier has
been determined from the temperature dependence of the
N M R spectrum.
Benzonorcaradiene ( I ) is produced [2] by the addition of
methylene onto naphthalene; its N M R spectrum shows, in
addition t o the signals due t o the four aromatic protons, a
doublet at 3.83 T (two olefinic protons), a multiplet at 7.83 T
(benzyl proton), a complex multiplet at 8.33 t (ally1 proton)
and multiplets at 8.70 and 10.35 T, assigned t o the two
methylene protons.
between the original signals. Further rise in temperature
increases the sharpness of this new band. The other signals
retain their positions.
These changes in the spectrum are completely reversible and
can be explained by an equilibrium between the antipodes
( l a ) and ( Ib ) , which is rapidly attained. As the protons
Ha and Hb formally change places during this process, the
positions of the N M R signals of Ha and Hb depend on the
rate of the inversion ( l a )
(Ib).
According t o Gutowsky and Holm [3], the rate constant for
such a proton exchange is given by the equation
+
k
/
1: 1
+
Received, March 23rd, 1964
IZ 702/523 1El
German version: Angew. Chem. 76, 432 (1964)
[ I ] For the synthesis of stable norcaradienes, see: E. Vogel, W .
Wiedemann, H . Kiefer, and W . F. Harrison, Tetrahedron Letters
1963, 673; R. Darms, T.ThrelfaII, M . Pesaro, and A. Eschenmoser,
Helv. chim. Acta 46, 2893 (1963).
[2] W . v. E. Doering and M . J. Goldsrein, Tetrahedron 5 , 53 (1959).
[3] H . S . Gutowsky and C. H. Holm, J. chem. Physics 25, 1228
(1956).
[4] Spin-spin interaction was not considered, although strictly
speaking the above treatment is valid only if (for k = 0) coupling
constants and line-widths are equal to zero; see S. Alexander, J.
chem. Physics 37, 967 (1962).
[5] Substitution of an H-atom of the CH2 group in ( I ) by another
group should not significantly affect the rate of isomerization to
the corresponding cycloheptatriene (2). However, with such
substituted benzonorcaradienes, the equilibrium concentrations
of ( l a ) and ( I b ) will in general by very different since the two
forms are now exo-endo isomers; the inversion of the threemembered ring can then no longer be observed by NMR spectroscopy. Thus, the NMR spectrum of benzonorcaradienecarboxylic ester is not temperature-dependent.
Phosphonic Ester En01 Phosphate Rearrangement
By Dr. H. Machleidt and Dr. G. U. Strehlke
Organisch-Chemisches Institut der Universitiit Bonn
(Germany)
The reaction of bromoacetone ( I ) with triethyl phosphite at
140-170°C gives rise t o compounds (2) and (3) [I], in the
approximate ratio of 1 : 1. On prolonged heating, this proporH, P
H3C-C-C+lP(OR),
t; A36
(1)
1 la)
= il(&A)
where 6 is the chemical shift of the two protons at infinitely
small rate of exchange, and A is the frequency interval
between their signals at the temperature of observation; the
( I b ) between
rate constants for the isomerization ( l a )
150 and 180°C were determined in this way. Evaluation
according to the Arrhenius equation gave the activation
1011 sec-1 [4].
parameters E, = 19.4 kcal/mole and A = 6 . 2 ~
The isomerization ( l a ) % ( I b ) is considered t o be a consequence of a norcaradiene-cycloheptatriene equilibrium
which reveals its existence in the interconvertibility of
the antipodes ( l a ) and (16) [5]. With the assumption that
kz 9 kl (the concentration of (2) remains below that detectable by N M R spectroscopy), the energy barrier for the
norcaradiene-cycloheptatriene rearrangement ( I ) s (2) is
19.4 kcal/mole and the frequency factor A = 1 . 2 1012
~ sec-1.
R
-RB;- HsC-C-CH,
b
(2)
$OR),
0
(lb)
(2)
On heating, the methylene signals first lose their fine structure; they then broaden until at 18OoC, they merge t o a
uniform flat absorption band which lies midway (9.54 T)
Angew. Chem. internat. Edit.
/
VoI. 3 (1964)
1 No. 6
443
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