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Azoalkanes by Anodic Oxidation of Anions of N N-Dialkylsulfamides.

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If (2) is subjected to thermal decomp~sition[~l
in the
presence of the thiapseudophenalenones (4)L41 and ( 6 a j(6c)['], then dicyanoketene ( 3 ) reacts to form the otherwise
inaccessible thiapseudophenafulvenes ( 5 ) and (7a)-( 7 c ) ;
R3
(6)
tor with exclusion of moisture, yield: 780mg (74 %) of (2);
IR (KBr): 2240, 2210 ( S N ) , 2155, 2100 {N3),1660 (C+O),
1560 cm-' (C=C); UV (CH,CN): im,,=334nm (~=25300),
260 (17 300), 226 (15 OOO).
Synthesis of ( 5 ) , (7aj-(7c),
(8)-(10):
A 0.25mmol
sample of ( 4 ) , (6 a)-(6c), diphenylcyclopropenone, tropone,
or phenalenone and (2) (90.0mg, 0.375mmol) are refluxed
in anhydrous benzene (25 ml) under Nz for 4 h. The evaporated
solution is applied to a silica gel PLC plate (PSC Kieselgel,
"Merck) and developed with dichloromethane. The reddish
fractions (yellowin thecase of ( 9 ) ) are extracted with dichloromethane (Soxhlet)and the solutions carefully evaporated. The
physical data of ( 5 ) and (7a)-(7c)
are listed in Table 1.
Received: February 3, 1978;
revised: March 3, 1978 [Z 953 IE]
German version: Angew. Chem. 90, 395 (1978)
[l]
121
[3]
the paramagnetic shift of the 'H-NMR signals suggests polarization of these products.
[4]
[5]
[6]
[7]
[XI
The dicyanofulvenes(8)'6J(yield: 26 %), (9)"' (yield: 20 %),
and (lo)[*] (yield: 37%) which we obtained from dicyanoketene ( 3 j and diphenylcyclopropenone, tropone, and phenah o n e were identical with authentic material in their physicochemical and spectroscopic properties.
Table 1. Physical properties of compounds ( 5 ) and ( 7 a j - - ( 7 c )
(5):m.p.253-254"C;
yield: 54 %; M + =234.0247(calc.: 234.0251); 'H-NMR
(CDClj): 6=8.06 (s, H2), 7.49 (d, H3, J=9.7Hz), 7.45 (d, H4, J=9.7Hz),
9.13 (d of d, H6, J,,,h0=7.9Hz, Jm,,.=0.17H~), 7.71 (t, H', Jorf,,o=7.9H~,
Jortho=7.9HZ),8.81 (d of d, Ha, J0,,h,=7.9Hz, Jmet0=0.7Hz);UV (CH3CN):
i,,,=456nm (&=24760),305 (4430). 273 (5760), 242 (10000)
(7a): m.p. 222-223°C; yield: 48 %; M+=234.0247 (calc.: 234.0251); 'HNMR ([D6]-acetone): 6=9.64 (s, H'), 7.42 (d, H4, J=9.4Hz), 7.87 (d, H5,
5=9.4Hz), 7.93 (d of d, H6, Jarlho=7.5Hz,Jm,,,=l.2Hz), 7.77 (t, H', J O r t h o
=7.5HZ, Jortha=7.5Hz), 8.31 (d ofd, Ha, Jur,ho=7.5Hz,Jm,,,=1.2Hz); UV
(CH3CN): E.,.,=458nm
(~=16050),323 (3105), 264 (18220), 239 (10490)
( 7 b ) : m.p. 188-189°C; yield: 3.2 %; M+=248.0404 (calc.: 248.0408); 'HNMR ([D,]-acetone): 5=3.01 (s, CH3), 7.55 (d, H4, J=9.5Hz), 7.86 (d,
H5,5=9.5Hz), 7.91 (d o f d , H6, J,,,h,=7.6Hz, Jm,,,=1.2Hz), 7.70 (t. H',
Jorrho=7.6HZ, Jorth.=7.6HZ), 8.23 (d of d, Ha, Jortho=7.6Hz, Jmet,=1.2Hz);
UV (CH3CN): /.,.,=457nm
(&=19160),324 (5350), 267 (20760), 248 (18650)
(7c): m.p. 270°C (dec.); yield: 27 %; M + =301.9468 (calc.: 301.9472); 'HNMR ([DsI-DMSO): 5 ~ 9 . 6 0(s, H'), 7.32 (d, H4, J=9.5Hz). 7.85 (d, H5,
J =9.5 Hz), 7.98 (s, H'); UV ( CHKN): i
,
,
=480nm
,
(&= 18 170), 459 (19340),
325 (2120), 272 (21610), 246 (12830)
Experimental
Synthesis of (2): A 25 % aqueous solution of sodium azide
(2.6m1, 10mmol) is added to a stirred solution of (I) (1.00g,
4.40mmol) in THF (20ml) at -5°C. The product is precipitated from the red solution by addition of ice-water ( W m l ) .
The orange crystals are filtered off after a few minutes, the filter
crucible being cooled with ice. The crystals are washed several
times with cold ether, dried in vucuo,and stored in a refrigera370
K . Walienfels, G. Bachmann, D. Hofmann, R. Kern, Tetrahedron 21, 2254
(1965).
R. Neidlein, G. Humburg, Chem. Ber., in press.
W Weyler, W G. Duncan, H . W Moore, J. Am. Chem. SOC. 97, 6187
(1975), and references cited therein.
E. Campaigne, D. R. Knapp, J. Heterocycl. Chem. 7, 107 (1970).
R. Neidlein, K . F . Cepera,, Justus Liebigs Ann. Chem., in press; R.
Neidlein, G . Humbug, ibid. 1977, 904.
E. D. Eergmann, I . Agranat, J. Am. Chem. SOC.86, 3587 (1964).
?: Nozoe, T Mukai, K . Osaka, Bull. Chem. Soc. Jpn. 34, 1384 (1961);
K . Hafner, H . W Riedel, M . Danielisz, Angew. Chem. 75, 344 (1963);
Angew. Chem. Int. Ed. Engl. 2, 215 (1963).
H. Prinzbach, V Freudenberger, Angew. Chem. 77, 346 (1965); Angew.
Chem. Int. Ed. Engl. 4,243 (1965).
Azoalkanes by Anodic Oxidation of Anions of N,"Dialkylsulfamides [**I
By Reinhold Bauer and Hartmut Wendt ['I
Hypochlorite oxidation of ammonia, alkylsulfamides or
geminal diamines is the usual reaction path to hydrazine, substituted hydrazines or azoalkanes, respectively"]. The anodic
oxidation of anions of primary and secondary amines in aprotic
solvents opens another route to N-N-coupling products"].
This electrochemical method can also be used for the anions
of N,N'-dialkylsulfamides (I) and thus offers the possibility
of carrying out anodic N-N-coupling in protic solvents, in
a reaction which is easy to perform and which affords azoalkanes in about 90 % yield with attractive current efficiencies.
Table 1 lists the anodic half-wave potentials of some sulfamides
(1 ) and their monoanions (2 j . The anions are generally oxidized in a one-electron step at potentials which are 600 to
800mV more negative than the half-wave potentials of the
corresponding sulfamides. Oxidation products are the azoalkanes ( 4 ) . Table 2 lists mass yields and current efficiencies
for the potentiostatic oxidation of (2).
Table 1. Anodic half-wave potentials of N,N'-dialkylsulfamides and their
anions in methanol at a carbon electrode with 0.1 M n-Bu4BF4 as supporting
electrolyte (E,/' [mV] measured us. aqueous SCE).
R
RHN-SOZ-NHR
n-Butyl
t-Butyl
Cyclohexyl
Adamantyl
1655
1650
I520
1510
(1 j
RHN--SO,-NReLie
(2)
850
loo0
880
910
[*] Dip].-Ing. R. Bauer, Prof. Dr. H. Wendt
Institut fur Chemische Technologie der Technischen Hochschule
Petersenstr. 20, 6100 Darmstadt (Germany)
[**] This work was supported by the Deutsche Forschungsgemeinschaft.
Angew. Chem. Int. Ed. Engl. 17 ( 1 9 7 8 ) N o . 5
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
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oxidation, anodic, dialkylsulfamides, azoalkanes, anion
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