close

Вход

Забыли?

вход по аккаунту

?

Dianion and Tetraanion Octalene.

код для вставкиСкачать
amine (13b j afforded 8.5% trans-I-bromo-2-methoxymethylcyclopropane (14 b ) .
The trans-amines (1 3 a, b ) yielded only traces of cyclopropyl
bromides. This finding is consistent with a substitution with
inversion, which in the case of the trans-diazonium ions is
sterically hindered by the 2-substituents, so that it can no
longer compete with ring cleavage.-The allyl alcohols (12)OH and (15)-(OH)are formed stereospecifically via disrotation. The corresponding allyl bromides (X=Br) are not configurationally stable.
Our results refute-at least for nitrogen as leaving g r o u p
the concept of a retentive SN2-substitutionat the cyclopropane
ring. Retention of configuration is only observed when the
disrotatory cyclopropyl-ally1 rearrangement is initiated, but
cannot be led to completion owing to opposing ring strain;
in these cases partly opened cyclopropyl cations are probably
involved as intermediates. In the case of unconstrained ring
cleavage the competing substitution at cyclopropanediazonium ions proceeds with inversion.
Received: January 4, 1979 [Z 162 IE]
German version: Augew. Chem. 91, 240 (1979)
P. D. Gillespie, I . Ugi, Angew. Chem. 83, 493 (1971); Angew. Chem.
Int. Ed. Engl. 10, 503 (1971); W D. Stohrer, K . R. Schmieder, Chem.
Ber. 109, 285 (1976).
[2] C . A. Marganoff, F . Ogura, K . Mislorv, Tetrahedron Lett. 1975, 4095;
7: Vergnani, M. Karpf, L . Hoesch, A. S. Dreidiny, Helv. Chim. Acta
58, 2524 (1975); T EI Gomati, J . Gasfeiger, D. Lenoir, I. Ugi, Chem.
Ber. 109, 826 (1976).
a) U . SchrillkopL Angew. Chem. 80, 603 (1968); Angew. Chem. Int. Ed.
Engl. 7, 588 (1968); P. L'. R. Schleyer, W F. Sliwinski, G. W Van Dine,
U . Schollkopf, J . Paust, K . Fellenberger, J. Am. Chem. SOC.94, 125
(1972); b) retentive substitution was found for 2,3-benzo-1l-bromotricyclo[4.4.1 .0'.h]undec-2-en-4-one: H . Yumaguchi, K . Kawada, I:Okamoto,
E . Egert, H . J . Lindner, M . Braun, R . Dammann, M. Liesner, H . Neumann,
D. Seebath, Chem. Ber. 109, I589 (1976); the reaction probably proceeds,
however, according to an elimination-addition mechanism: R. W Gray,
C . 8. Chupleo. I: Vergnani, A . S . Dreiding, M. Liesner. D . Seebach, Helv.
Chim. Acta 59, 1547 (1976); H . J. Lindner, B. Kirschke, M . Liesner,
D.Seebuch, ibid. 40, 1151 (1977); c) the reaction of cis- or trans-(2-benryloxycyclopropy1)trimethylammonium iodide with H I / H 2 0 gave trans(hydroxycyclopropyl)trimethylammoniumiodide: H . Kunze, 2. Naturforsch. 8.11, 1676 (1976).
W Kirmsr, H . Jendralla, Chem. Ber. I l l , 1857 (1978).
W Kutzelnigg, Tetrahedron Lett. 1967, 4965; D. ?: Clark, G . Smale,
Tetrahedron 25, 13 (1969).
G . L . Thompson, W E . Heyd, L . A . Payuerte, J. Am. Chem. Soc. 94,
3177 (1974).
P. M. Warner, S.-L. Lu, E . Myers, P. W De Haven, R . A . Jacobson,
J. Am. Chem. SOC.99, 5102 (1977).
G . A. Oluh, G. Liang, D . B. Ledlie, M . G . Costopoulos, J. Am. Chem.
Soc. 99, 4196 (1977).
Synthesis of (E)-[2,2,3-D~]-cyclopropanecarboxylicacid: K . Kobagushi,
1. B. Lumbert, J. Org. Chem. 42, 1254 (1977). This was used for the
preparation of ( 1 0 ) by Curtius-degradation.
[I]
Aiigew. Ciiem. i n t . Ed. Engl. 18 (1979) ,A',)
Dianion and Tetraanion of Octalene
By Klaus Miillen, Jean F. M . Oth, Hans-Wilhelm Engels, and
Ernanuel Vogel['I
The I3C- and 'H-NMR spectra of octalene['l recorded
at - 150°C reveal the molecule to show n-bond localization
in the ground state and to exist in the double bond configuration depicted in formula ( 1 ) . Octalene is not planar, does
not possess any element of symmetry, and is therefore chiral.
Moreover, as temperature-dependent NMR studies (between
- 150 and + 140°C) also show, octalene undergoes fast isodynamic processes: at very low temperatures the cyclooctatriene or/and the cyclooctatetraene ring inverts, and above
ca. 70°C a n-bond shift occurs[? The olefinic nature of this
potentially aromatic 14n-electron system is readily explained
by the inadequacy of the delocalization energy to overcome
the strain of flattening the eight-membered ringsL3].
Mono- and polycyclic x-electron systems are subject to
far-reaching changes in their n-bonding and geometry on electrochemically or alkali-metal induced reduction to anionsr4].
In the case of octalene, the preparation of anionic derivatives
appeared particularly attractive since the construction of this
(4n + 2)n-system from two (4n)n-cyclooctatetraene fragments
permits various possible charge distributions in the ionic species and thus also various possible structures.
Measurement of the classical polarograms [dimethylformamide, tetra-n-butylammonium perchlorate as supporting electrolyte, calomel electrode (SCE), 1 N KCI as reference] shows
that octalene can accept four electrons on reduction. Cyclic
voltammetry and potential jump experiments also indicate
that the first electron is transferred reversibly at Eliz= - 1.67 V
and the three other electrons in a joint wave at Eliz= - 1.70 V.
This second wave corresponds to chemically reversible processes since no secondary reactions are observed under strictly
aprotic conditions; however, the electron transfers themselves
are irreversible in that the reoxidation potentials are distinctly
shifted towards more positive values relative to the reduction
potentials. The electrochemical results[51suggested that octalene (1 j should form a radical anion ( 1 )y, a dianion ( 2 ) ,
a radical trianion ( Z j y , and a tetraanion (3) on reduction
by a metal.
We have therefore exposed octalene (in [D8]tetrahydrofuran) to the action of lithium for defined periods of time
and carefully checked the progress of reduction by recording
the 'H- and 13C-NMR and ESR spectra. After brief contact,
a radical anion can be detected in the solution which has
turned from pale yellow to red. As shown by the 'H- and
I3C-NMR spectra, the neutral and the radical species present
are accompanied by a new diamagnetic compound to be
regarded as the dianion (2). The reduction can be interrupted
at a stage where this ion is present exclusively. Figure 1
shows the relevant 'H- and 13C-NMR spectra (see also Table
1). The four signals in the I3C-NMR spectrum of the dianion
[*] Prof. Dr. K. Mullen, Prof. Dr. J. F. M. 0 t h
Laboratorium f i r Organische Chemie der Eidgenossischen Technischen
Hochschule
Universitatstrasse 16, CH-8092 Zurich (Switzerland)
Dip1.-Chem. H.-W. Engels, Prof. Dr. E. Vogel
Institut fur Organische Chemie der Universitat
Greinstrasse 4, D-5000 Koln 41 (Germany)
i
0 Verlag Chemir, GmbH, 1)-6940 Weinheim, 1979
229
0570-0833/79/0303-0229 $02.30/0
Table 1 . 'H- and I3C-NMR chemical shifts of octalene ( I ) [a], its dianion
(2). and its tetraanion ( 3 ) [b] (6 values relative t o TMS; in [Ds]THF
at -80°C).
I
1,
____
C-l,C-6,
C-7.C-12
/ li
'H-NMR
6.39 (H-I, 6)
5.54
5.78
5.78 (H-I, 6, 7, 12)
5.32
(6) = 5.88
(6)= 5.47
(6) = 5.54
A ( R ) =0.41
IZi
A(6)=0.07
"C-NMR
I
131
143.15 (C-13, 14)
136.94 ((2-1, 6)
131.89
131 1 9
129.45
127.99
127.17 (C-7, 12)
(6) = 132.62
129.85 (C-I, 6, 7, 12)
1 1 I.49
103.54
93.85 (C-13, 14)
100.37
R6.84
75.70
89.96 (C-13,
(6)= 111.94
(6)
8
7
6
-&5
4
3
2
1
140
-
100
€0
bc-
Fig. I. 'Hand "C-NMR spectra of octalene ( I ) , its dianion ( 2 ) . and its
tetraanion (3) (as lithium salt) ([D,]-THF, -80°C).
suggest DZhmolecular symmetry and hence structure ( 2 a )
with n-bond delocalization. In view of the total number of
71-electrons (14+2= 16=4n), structure ( Z b ) containing a cyclooctatetraene dianion fragment would appear more likely.
In such a case, the observed I3C-NMR can only be rationalized
by assuming a fast charge transfer coupled with a n-bond
shift [(Zb)$(2L1)][~1.
Further reduction transforms the dianion (2) into a new
diamagnetic anion which, like (Z), exhibits four signals in
the I3C-NMR spectrum (no ESR signals appear in the case
of this reduction) and must therefore also have DZhsymmetry.
After prolonged contact between the metal and the solution,
which has meanwhile become dark brown, only the signals of
this species are observed. Thus, it is reasonable to assume that
the tetraanion (3) with a delocalized 18n-system is present.
(3)
Identification of the diamagnetic ions as dianion and
tetraanion of octalene follows from the specific course of
the reduction (i. e. the appearance and disappearance of the
individual species), from the characteristics of the WMR spectra, and also from reoxidation experiments. Oxidation of the
partially or completely reduced solution [(Z) or (31, respectively] with oxygen gave octalene as the sole identifiable
product.
On going from ( I ) to ( 2 ) and ( 3 ) , the centroid of the
l3C-NMR signals underwent an upfield shift as expected from
the known correlation of 13C-NMR chemical shifts and ncharge densities['! Moreover, the observed sequence ofassigned
signals can be predicted on the basis of local Ir-charge densities.
In contrast to I3C-NMR chemical shifts, which mainly ieflect
the charge densities, the 'H-NMR chemical shifts are also
230
= 87.96
A(6) =23.98
A(;i)=20.68
~
~
~-
[a] "C-NMR averaged spectrum [2] owing t o fast ring inversion(s) at
-80°C. [b] Owing to thesparingsolubilityofthe tetraanion ( 3 ) the resonance
of the quaternarycarbon atoms could only beobserved at a low signal-to-noise
ratio (2: I)and is therefore unreliable.
affected by field-induced ring currents. The surprisingly small
upfield shift of the centroids of the 'H-NMR signals seen
on going from (I) to (2) (A(6)=0.41) and from (2) to
(3) (A(6) =0.07) indeed suggests that the charge-induced
upfield shift is largely compensated by the effect of a diamagnetic ring current.
In the (4nf2)n-system (3) the existence of a diamagnetic
ring current complies with expectation, while this applies to
( 2 ) only if the anion has structure ( Z b ) with a fast charge
shift [structure ( 2 a ) would show a paramagnetic ring current18']. Attempts to elucidate this structural problem are
currently in progress.
The I3C- and 'H-NMR spectra recorded during the reduction provide information about the relative energies of the
octalene anions. When the ESR signals of the radical anion
( 1 ) ; has reached maximum intensity, the I3C- and 'H-NMR
spectra are each a superposition of the individual spectra
of ( I ) and (2) (with only minimal line broadening). Hence
it follows that the radical anion is extensively disproportionated and that the rate constants of all the bimolecular
electron transfer reactions are slow on the NMR time scale.
Similar arguments apply to the disproportionation of the
radical trianion ( 2 ) : into (2) and (3).
The fact that a relatively small molecule like octalene can
accept four electrons at low (i. e. not very negative) potentials
is surprising in view of the Coulomb forces involved[91.According to the results described, the energy gain from delocalization
of charges and n-bonds in the tetraanion (3) is so large
that it overcompensates both the electrostatic energy and
the strain energy associated with flattening of the molecule[21.
The new bicyclic (4n + 2)n-species ( 3 ) , which is stable for
several days at room temperature (in tetrahydrofuran with
exclusion of air), can be regarded as an analogue of naphthalene: like the latter, it possesses a perimeter with n-bond
delocalization and consists formally of two annelated (4n + 2)nfragments.
Received: December 28, 1978 [ Z 164 IE]
German version: Angew. Chem. 91, 251 (1979)
E. Vogel, H . - K Runzheimer, F . Hogrefe, B. Baasner, J . Lex, Angew.
Chem. 89, 909 (1977); Angew. Chem. Int. Ed. Engl. 16, 871 (1977).
[2] J . F. M . Oth, K. Miillen, H.-f! Runzheimer, P . Mucs, E. Vogel, Angew.
Chem. 89, 910 (1977); Angew. Chem. Int. Ed. Engl. 16, 872 (1977).
[I]
A q e w . Clzem. l i l t . Ed. Engl. 18 (1979) No. 3
0 Verlag Chenrie, GrnhH, 0-6940 Weinherm, 1979
0570-0833/79/0303-0220
s 02.50J0
[3] N . L. ,4/linger, C . Gilardeau, Tetrahedron 23, 1569 (1967); D . H . Lo,
M . A. Whitehead, J. Am. Chem. Soc. 91, 238 (1969).
[4] J . F . M . 0 t h . K . Miillen, H . K~nigshoJen,J . Wassen, E . Vogel, Helv.
Chim. Acta 57, 2387 (1974); 7: J . K a t z , J. Am. Chem. Soc. 82, 3784
( I 960).
[5] J . F . M . Oth, K . Miillen, to be published.
[6] The 'H-NMR data support structure ( 2 b ) .
[7] G. A Olah, G. D. Mateescu, J . Am. Chem. Soc. 92, 1430 (1970).
181 O n the basis of the 'H-NMR chemical shifts of cyclooctatetraene and
its dianion, an upfield shift of 0.05 would be predicted for the centroid
of the signals of (2) [as structure ( 2 b ) ] relative to ( I ) .
[9] A similar situation is encountered in the reduction of biscyclooctatetraenyl [ J . F . M . Orh, K . Miillen, unpublished; see also L. .4. Paquette,
G. D. Ewing, S. G. Traynor, J. Am. Chem. Soc. 98, 279 (1976)l during
the course of which we were able to prepare the dianion and tetraanion
(as the lithium salts) and t o characterize them by 'H-NMR and "CNMR In this molecule, which is suitable as a reference system for
the understanding of the reduction of octalene IS], the Coulomb forces
operative on formation of the tetraanion are less serious.
Co-N bond length (mean value 2.093(11)A) approximates to
that in [Co(NH&I2+ (2.114(9)A)[']. The NSF angle changes
only slightly on formation of the complex; noteworthy is the
pronounced shortening of the SF and SN bonds: ( 3 a ) shows
the shortest SN bond so far recorded! The mean CONS
angle is 170.8(10)".As can be seen from Figure 1, the S- and
N-atoms are almost isotropic, although the F-atom vibrates
anisotropically. This would indicate that appreciable librational
shortening is to be expected only in the S F bond.
Stable CoordinationCompounds of "Thiazyl Fluoride":
Structure of [CO(NSF)~]' in the Crystal[**]
+
By Bruno Buss, Peter G . Jones, Riidiger Mews, Mathias Noltemeyer, and George M . S/zeldrick[*]
The simplest nitrogen-sulfur-fluorine compound, the monomeric "thiazyl fluoride" (1) is unstable at room temperature[". Stabilization of the molecule can be achieved, however,
by incorporation as ligand in transition metal complexes:
6NSF
+ [M(SO,l,]( 'i\F,)z
(2)
(1)
--+ [M(NSF)6](ASF6)2
so2
(3 a), M = CO
-
Fig. 1. Structure of the cation Co(NSF)H+ in the salt ( 3 a ) . M,=827.17,
monoclinic, P2,/n, a = 13.105(9), b=9.201(7), c=9.366(6)& /$=90.43(4)",
).
deterV=1129A3, Z = 2 , pca1c=2.432gcm-3,p = 4 3 c m - ' ( M O K ~ Structure
mination from diffractometer data by direct methods. Refinement, with structure factors of 1102 reflections corrected for absorption [F>4o(F)], to a
current R value of 0.083.
(3b), M=N1
Experimental
The hexakis(thiazy1 fluoride) complexes of Co" and Ni" are
formed in almost quantitative yield on reaction of the hexafluoroarsenates (2 j with an excess of NSF in liquid SO2 below
-20°C. In the crystalline state the salts (3) are stable in
dry glass vessels at room temperature, whereas in solution
ligand-exchange takes place:
[M(NSF),Iz'
5ml of SO2 and a 10-20 x) excess of NSF are condensed
into 1-2 g (2-4 mmol) of the corresponding SO2-complex
(2)14] at - 196°C. After stirring for 2-3 hours at -20°C the
reaction mixture is filtered and solvent and excess ligand
reagent removed from the filtrate by evaporation. There remain
the analytically pure products.
Received: December 14, 1978 [Z 166 IE]
German version: Angew. Chem. 91. 253 (1979)
+ x SO1 G [M(NSF)6 -.(S02),]*' + x NSF
(4a), M = C o
(46), M = N i
The isolable salts then have a composition with O i x i l
[( 4 a ) : v,,(SO) = 1326, v,(SO) = 1 1 55 cm ; ( 4 b ) : v,,(SO) =
1327, v,(SO)=1161 cm-'1.
The IR spectra of the complexes ( 3 a ) and ( 3 b ) show
a strong shift of the SN stretching vibration to higher wave
numbers; vSF also increases:
~
N=S-F
(Gas)
[Co(NSF),]'
[Ni(NSF),] *
+
+
I'Sh
1'SF
dw
dsF
3: NSF
[cm-'1
[cm-'I
[A]
[A]
["I
1361
1429
1438
641
655
655
1.446
1.646
116.5 [a]
1.399(12) 1.569(12) 115.0(7) [h]
-
-
~
[l] 0. Glemser, H . Schriider, E. Wyszomirski, 2. Anorg. Allg. Chem. 298.
72 (1959); 0. Glemser, H . Meyer, A . Haas, Chem. Ber. 97, 1704 (1964).
[2] H . Richert, 0. Glemser, Z . Anorg. Allg. Chem. 307, 328 (1961); W H.
Kirchhoff;E. B. Wilson jr., J . Am. Chem. Soc. 85, 1726 (1963).
131 N . E . Kime, J . A. Ihers, Acta Crystallogr. B25, 168 (1969).
[4] C . D . Desjardins, J . Passmore, J. Fluorine Chem. 6, 379 (1975); P. A.
W Dean, ibid. 5, 499 (1975).
Facile Synthesis of Cyclopropylalkadienes[**]
By Manfred Schneider and Angelika Rau[*]
In contrast to the synthesis of cyclopropylalkenes there
are only few methods known for the preparation of cyclopropylalkadienes. Their synthesis is of interest in connection with
[a] Cf. [Z]: [h] mean values
The X-ray structure analysis of ( 3 0 ) also indicates an
increase in SN and SF bond strength. The central atom [on
the special position (0,0, O)] is octahedrally coordinated; the
[*] Prof. G . M. Sheldrick, Dr. B. Buss, Dr. P. G. Jones, Priv.-Doz. Dr.
R. Mews, Dr. M. Noltemeyer
Anorganisches Institut der Universitat
Tammannstrasse 4, D-3400 Gottingen (Germany)
[**I This work was supported by the Niedersachsiches Zahlenlotto. We
thank Cambridge University for the use of a diffractometer.
Dictyopterene B
[*I
[**I
D i c t y o p t e r e n e D'
Priv.-Doz. Dr. M. Schneider, A. Rau
Institut fur Chemie der Universitat Hohenheim
Postfach 106, D-7000 Stuttgart 70 (Germany)
This work was supported by the Deutsche Forschungsgemeinschaft.
AngeM'. Cliein. lilt. Ed. Engl. 18 (1979) N o . 3
0 Verlag Chemie, GmbH, D-6940 Weinheirn, 1979
Dictyopterene D
231
0570-0833J79J0303-0231 $02.SOfO
Документ
Категория
Без категории
Просмотров
1
Размер файла
347 Кб
Теги
octalene, tetraanion, dianion
1/--страниц
Пожаловаться на содержимое документа