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Facile Preparation of Cyclooctatetraene from 1 5-Cyclooctadiene by Metalation and Oxidation.

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Table 2 Mass yields and current efficiencies for some reactions ( 2 ) - ( 4 )
in methanol a t C- and Pt-electrodes.
_
.
R N = N R (4)
R
Mass yields [ %]
Carbon
Platinum
Current yields [%I [a]
Carbon
Platinum
n-Butyl
t-Butyl
Cyclohexyl
Adamantyl
88
81
90
78
68
63
74
61
94
84
93
79
72
62
77
60
[a] Assuming consumption of two electrons per molecule of azoalkane in
accordance with equations (a) and (b).
A detailed investigation shows that the cyclic thiadiaziridine
1,l-dioxide (3) is formed as a primary oxidation product
of the formal one-electron oxidation (being in fact a sequence
of charge transfer, deprotonation and second charge transfer)
[Eq. (a)]. In the case of the N,N'-diadamantyl derivative,
after the electrolysis (3) could be isolated in small amounts
(1 0 %) besides the 1,l'-azoadamantane. The three-membered
heterocycles with spatially less demanding N-alkyl groups
slowly decompose in a well known thermal reaction to SO2
and the azoalkanes ( 4 J C 3 [Eq.
]
(b)].
Anodic oxidation of N,N'-dialkylsulfamides in the absence
of base leads merely to fragmentation and not to N-N-coupling. Since azoalkanes can easily be converted into hydrazines
by catalytic hydrogenation the described method provides
access also to symmetrically substituted hydrazinesL4?This
new anodic synthesis is based on direct anodic conversion
of N-anions in protic solvents and avoids the use of chlorine
or hypochlorite as oxidants.
Experimental
[2] R. Bauer, H . Wendt, Angew. Chem. 90, 214 (1978); Angew. Chem. Int.
Ed. Engl. 17, 202 (1978).
131 H . Quast, F . Kees, Chem. Ber. 110, 1780 (1977); J . W Timberlake, M .
L. Hodges, .4. W Garner, Tetrahedron Lett. 1973, 3834; J . W Timberlake,
M . L. Hodges, J. Am. Chem. SOC.95, 634 (1973).
[4] J . C . Srowell, J. Org. Chem. 32, 2360 (1967).
[5] H . H . Harkms, H . L. Lochte, J. Am. Chem. SOC.46,450 (1924).
[6] R . Ohme, H. Preuschhof, Justus Liebigs Ann. Chem. 713, 74 (1968).
Facile Preparation of Cyclooctatetraene from 1,5-Cyclooctadiene by Metalation and Oxidation
By Wolfgang Gausing and Giinther Wilke[*]
Metalation of olefins is attracting increasing interest; particular mention should be made of the formation of the trimethylenemethane dianion from isobutene['] and of the cycloheptatrienyl trianion from various C,-di- and tri-olefin~~~!
1,4-Cyclooctadiene is transformed into bicyclo[3.3.0]oct-2-ene by
lithiation and protolysi~[~!
We now wish to report the metalation of 1,5-cyclooctadiene
( 1 ), of 1,3-cyclooctadiene (2), and of 1,3,5-cyclooctatriene
( 4 ) and its 1,3,6 isomer ( 5 ) . The 1,5-diene ( I ) was expected
to react with n-b~tyllithium-tetramethylethylenediamine[~~
(BuLi'TMEDA) in the molar ratio 1 : 1 to give the ally1 anion
(3). On protolysis of the product, however, we obtained not
only ( 1 ) and its isomers but also the trienes ( 4 ) and ( 5 )
and hydrogen. The product apparently contained Li2(C8H8)[51
and LiH.
Reaction of ( 1 ) with BuLi.TMEDA in a ratio of 1 : 3 gives
LiH and crystalline Li2(C8H8).2TMEDA(6) in practically
quantitative yield: the latter product affords cyclooctatetraene
(7) in 90-95 % yield (based on (1)) on oxidation with
1' .
CdC12[5b,
In an attempt to simplify this new synthesis of cyclooctatetraene for preparative purposes we have tried other metalation
and oxidizing agents. A particularly suitable procedure proved
to be the initiaI reaction of ( I ) with phenylsodium in the
presence of TMEDA followed by oxidation with dry oxygen.
Formation of (7) is accompanied by a mixture of sodium
peroxide and hyperoxide"].
The results of reactions of (2), ( 4 ) , and ( 5 ) with n-butyllithium helped to elucidate the reaction mechanism: under the
N,N'-dicyclohexylsulfamide (5.20 g, 0.02 mol) is dissolved
in dry methanol (100ml) and converted into the lithium
salt by addition of an equimolar amount of Li-methoxide.
This solution is oxidized at controlled potential at a carbon
electrode in a divided cell at 273 K under a N 2 atmosphere.
After consumption of 0.04F the solvent is removed and the
residue is extracted twice with 50 ml of n-pentane. Subsequent
drying of the combined extracts over Na2S04 and removal
of the solvent by evaporation affords 2.73 g (90 % mass yield
and 74'%;current yield) azocyclohexane, m.p. 307 K (RefJ5]
307.5 K). The product was identified by comparing its spectroscopic data (MS, IR, UV, 'H-NMR with those of an authentic sample prepared according to the procedure of Ohme et
al.'6'.
Received: February 20, 1978 [ Z 956 IE]
German version: Angew. Chem. 90, 390 (1978)
CAS Registry numbers:
( I ) , R=n-butyl, 763-11-1; ( 1 ) . R=r-butyl, 13952-67-5; ( I ) , R=cyclohexyl,
14041-87-3; ( I ), R=adamantyl, 42399-75-7; (21, R=n-butyl, 66255-51-4;
( 2 ) , R=t-butyl, 66255-52-5; ( 2 ) , R =cyclohexyl, 66255-53-6; (2), R =adamantyl, 66255-54-7; (4), R =n-butyl, 21 59-75-3; (41, R = t-butyl, 927-83-3;
( 4 ) , R=cyclohexyl, 2159-74-2; (4), R=adamantyI, 21245-62-5
[ l ] R. Ohme, A . Zuhek, Z . Chem. 8, 41 (1968); R. Ohme, E. Schmitz, Angew.
Chem. 77,429 (1965); Angew. Chem. Int. Ed. Engl. 4,433 (1965).
Angew. Chem. Int. Ed. Engl. 17 (1978) N o . 5
(8)
Higher
hydrocarbons
[*I
(7)
Prof. Dr. G . Wilke, Dipl.-Chem. W. Gausing
Max-Planck-Institut fur Kohlenforschung
Kaiser-Wilhelm-Platz 1, D-4330 Mulheim-Ruhr (Germany)
371
same conditions neither 1,3-cyclooctadiene nor 1,3,5-cyclooctatriene can be converted in significant amounts into ( 6 ) ,
1,3,6-cyclooctatriene on the other hand reacts smoothly to
give this product; addition of the BuLi-reagent to (2) and
(4) does occur and in the case of (2) bicyclo[3.3.0]oct-2-ene
(8) is formed. This suggests that (1) and BuLi.TMEDA
initially form ( 3 ) . which is transformed into ( 5 ) bv loss of
LiH and TMEDA. Double metalation of ( 5 ) yields the intermediate (6).
H
H
H
H
H
H
Ilal
Procedure
Compound (1) (12m1, 10.6g, 98mmol) is added to
C6H5Nars1(0.31 mol) in olefin-free pentane (150 ml) and
TMEDA (95ml), and the mixture is stirred under reflux for
20 h. A slow current of dry O2 is then passed over the well
stirred mixture at -5°C for ca. 24h. After filtrationr7] the
solution is vacuum distilled, freed from TMEDA with S N
HC1, neutralized, anddried. G C analysis reveals 1.5 % (163mg,
1.5mmol) of (8) and 78.5 % (8 g, 76.9mmol) of (7), based
on quantitatively consumed (1). The remainder of (1) is
present as oligomerization product in the distillation residue.
Received: March 14, 1978 [Z 959 IE
German version: Angew. Chem. 90, 380 (1978)
CAS Registry numbers:
( I ) , 111-78-4; ( 2 ) , 1700-10-3; ( 4 ) , 1871-52-9; IS), 3725-30-2; (7), 629-20-9;
( 8 ) . 5549-09-7
[l] J. Klein, A. Medlik, J. Chem. SOC.Chem. Commun. 2973, 275.
[2] J. J. Bahl, R. B. Bates, W A. Beavers, C . R . Launer, J. Am. Chem.
SOC.99, 6126 (1977).
[ 3 ] R . B. Bates, D. A . McCombs, Tetrahedron Lett. 1969, 977.
[4] Cf. A. W Longer, Adv. Chem. Ser. 230, l(1974).
[5] a) I: J . Kutz, J. Am. Chem. SOC.82, 3784 (1960); b) I: A. Antkowiak
H . Shechler, ibid. 94, 5361 (1972).
161 As recently reported, ( I ) can be transformed into (7), albeit in poor
yield by reaction with potassium and subsequent oxidation: W J. Evans,
A . L . Wuyda, C.-W Chang, W M . Cwirla, J. Am. Chem. Soc. 100, 333
(1978).
[7] Caution! NaOl decomposes spontaneously with evoiution of O 2 on
exposure to water. The filter cake is sensitive to heat and shock when
dry.
[8] J . F. Nobis, L. F . Moormeier, Ind. Eng. Chem. 46, 539 (1954).
Benzenoid versus Annulenoid Aromaticity : Synthesis
and Properties of Kekulene[ ‘I
By Francois Diederich and Heinz A. Staab“]
In 1965, first attempts to prepare the hydrocarbon ( I )
were reportedr2].Then, at the centennial of Kekultf’s benzene
formula, this compound which may be regarded as a “superbenzene” on account of its planar cyclic conjugation and
D6,, symmetry was given the name “kekulene”[2~3].
(1) was
of interest in connection with investigations to experimentally
define benzenoid as against annulenoid aromaticity : on the
one hand, (1) can be formulated as a combination of two
[4n + 2]annulenes-[l Slannulene inside, [30]annulene outside-bridged by radial single bonds (I a), and on the other,
as a regular benzenoid system with a closed circle of angularly
annellated benzene rings ( l b ) . Since ( I ) , in this respect a
representative of a new class of aromatic compounds, has
an intramolecular cavity containing hydrogen atoms it should
be possible to decide by proton resonance whether an annuIenoid diatropism in the macrocyclic system can compete
successfully with ring-current induction within the benzenoid
subunits.
[*] Prof. Dr. H. A. Staab, Dip1.-Chem. F. Diederich
Abteilung Organische Chemie, Max-Planck-Institut fur mediziniscbe
Forschung
Jahnstrasse 29, D-6900 Heidelberg 1 (Germany)
372
H
llbl
In an attempt to synthesize ( I ) via a very involved and
tedious route Vogtle and S t ~ a b [were
~ ] able to show, on the
basis of a mass spectrometric analysis, that the desired compound was probably formed, albeit in minute and unisolable
amounts. Since preparation of (I) via such a route seemed
impossible all further efforts were abandoned 10 years ago.
Attempts by Tenny et
to prepare (11, which they named
‘[I Zlcoronaphene’ apparently were likewise unsuccessful.
Newly developed methods for C...C coupling in macrocyclic
systems, especially by sulfur extrusion from dithia[3.3]phanes,
prompted us now to resume our efforts to synthesize (1).
The first steps of the synthesis followed,with minor modifications, those of the previously reported synthesis of 5,6,8,9-tetrahydrodibenzo[~,j]anthracene‘~~.whose bromomethylation
according to the procedure used for 9,10-dihydrophenanthrend6], led to the bis(bromomethy1)derivative (2j’l in 50%
yield. After conversion of (2) into the bis(mercaptomethy1)
derivative (3)17] [thiourea method; 75 % yield, m.p. 243°C
(corr.)], (2) and (3) were cyclized to 6,7,9,10,23,24,26,27-octahydro- 2,19 - dithia [3.3] (3,ll)dibenzo[a,j] anthracenophaner’]
(4) [dilution apparatus of Vogtle; solutions of (2) and ( 3 )
in benzene (each 5.3 mmol in 3 500 ml) added dropwise and
simultaneously within 72 h into a boiling mixture of lo00 ml
benzene, 1000ml ethanol (95 %) and 4 g potassium hydroxide;
55 % yield]. (#)[’I:
yellowish platelets, m. p. 291 “C (corr.);
‘H-NMR (360 MHz, CDC13): 6=2.70 (s, 16H, H6,7,9,10,23,24,26,27), 3.82 (s, 8H, H-t,3,18,20), 6.73 (dd, 3 = 8
and 1.8Hz, 4H, H-13,17,30,34), 6.91 (s, 2H, H-8,25), 6.94 (d,
J z I . ~ H z , 4H, H-5,11,22,28), 7.40 (d, J = 8 H z , 4H, H14,16,31,33),7.83 (s, 2H, H-15,32).
6
7
8
IZI, X =Br
131. X = SH
141
Irradiation of (4) in trimethyl phosphite (450W Hg highpressure lamp, 2h, under N2) led in 60% yield to
5,6,8,9,21,22,24,25- octahydro[2.2](3.1 1 )dibcn/o[tr.i]anthra cenophane (5)171: colorless needleh. ni. p. 162 464°C. ( 5 ) ,
which had already been obtained in very unsatisfactory yield
(1.5%) from (2) by a Wurtz reaction (phenyllithium, ether/
benzeney41, was dehydrogenated with 2,3-dichloro-5,6Angew. Chem. Int. Ed. Engl. 27 ( I 978) N o . 5
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