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cis- and trans-Diazene (Diimine).

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with stirring into ice-water and the crude product extracted
into chloroform. The chloroform extract was passed through
a short (100 x 15 mm) column of silica gel and the residue
after removal of solvent was recrystallized from methanolwater to give (6d) as long silky needles (1.6g).
5-sec-Butyl-4,6-dichloro-2-phenylpyrimidine
( 6 b ) and 5-secBut):l-6-chloro-3-methyI-2-phenyl-4-pyrirnidinone(7 b): ( I b )
(3.0 g, 0.02 mol) and ( 4 a ) , (3.0 g, 0.02 mol) were reacted
together in POC13 as described above for ( 6 d ) . Chromatography of the product on silica gel using chloroform-petroleum
ether (b.p. 60--80°C) (1:l) as eluent gave ( 6 b ) as a pale
yellow oil (2.9 g) which, after solidification, crystallized
from ethanol in the form of colorless needles. Subsequent
elution of the column with chloroform gave ( 7 b ) as a yellow
oil (1.2 g), which solidified. Crystallization from a small quanity of petroleum ether (b.p. 60-80°C) gave colorless prisms.
Received: July 18, 1977 [Z 806 IE]
German version: Angew. Chem. 89, 816 (1977)
CAS Registry numbers:
( l a ) , 53260-43-8; ( I b ) , 63797-45-5; ( I c ) ~63797-46-6; ( I c ) , 63797-47-7;
(lr),63797-48-8;/4u),6l1-74-5;
( 4 6 1 , 127-19-5: (4c),68-12-2: ( 6 a ) , 3365533-3: ( h b ) .63797-49-9; (6c), 33655-34-4; ( 6 d ) , 33655-35-5;( 6 e ) , 63797-50-2;
(611,63797-51-3; ( ? a ) , 63797-52-4; ( 7 h ) , 63797-53-5; ( 7 c ) , 63797-54-6; ethyl
2-cyanopentanoate. 6967-47-1 ; cyclohexylamine, 108-91-8
~~
[I]
[2]
131
141
[5]
A . L. Cossey, R. L. N. Hurris, J. L. Hupparz, J . N. Phillips, Angew.
Chem. 82, 898 (1974); Angew. Chem. Int. Ed. Engl. 13, 809 (1974).
E. D.Alexunder. A . C . Cope, J. Am. Chem. Soc. 66,886 (1944).
D. J . Brown: The Pyrimidines. Interscience, New York 2962, Chap.
2 -3.
A. L . Cossey, R . L. N . Harris. J. L. Hupputz, J . N . Phillips, Aust.
J. Chem. 29, 1039 (1976).
S . Yunuyidr~.M . Yukoe, M . Ohoku, S. Komori, Bull. Chem. Soc. Jpn.
44,?1X2ll‘17lI
[6] The structures of :ill compounds reported are consistent with analytical,
NMR and mass spectral data.
A Novel Heteroaromatic System: 2,1,3-Benzothiadiazinylium Derivatives[**]
By Wolfgang Kosbahn and Helmut Schiiferr]
Analogously to pairs such as benzene/tropylium or thiophene/thiopyrylium, formal ring expansion of the well documented and extremely stable heterocycle 2,1,3-benzothiadiazole
(“piazthiol”)[llaffords the 2,1,3-benzothiadiazinyliumion (2).
We have now succeeded in preparing the first derivatives
of this ring system from the benzothiadiazinones ( I ) by directed alkylation at the oxygen:
Like the already known unsubstituted compound ( I ab)[’],
theeducts (1 c ) to ( 1 e ) are obtainable from the corresponding
substituted 2-aminobenzamides by reaction with N,N’-bis(ptoluenesulfony1)sulfur diimide in chloroform. The reaction
with oxonium salts in dichloromethane proceeds at room
temperature within a few minutes in the case of ( I ab), within
a few days in the case of ( I d ) . The products (2) can be
purified by dissolution in acetone and precipitation with
diethyl ether [yields between 13% ( 2 e ) and 85% (2a)I.
Their structure follows from the IR, ‘H-NMR and, in particular, from the I3C-NMR spectra. Noteworthy is the strong
deshielding influence of the N,S+ group on the atom C-6
located in the p-position; the substituent increment with about
+15.5ppm has almost the same value as the diazonium
The finely crystalline 2,1,3-benzothiadiazinyliumsalts (2)
have decomposition points between 1 11 and 165“C; they react
slowly with water with evolution of SO2.
(2 b ) reacts smoothly at room temperature with 1,3-dienes
such as 2,3-dimethylbutadiene, 1,3-pentadiene or isoprene,
whereby the double bond between N-I and S functions as
dienophile. The structure of the adducts (isolable in yields
of ca. 65%) follows above all from the t3C-NMR spectra.
The ease of addition and its pronounced regioselectivity can
be explained in terms of the frontier orbitals of the reactants:
According to PPP and CNDO/S calculations[41 the lowest
unoccupied molecular orbital (LUMO) of ( 2 ) , a K orbital,
is almost completely localized on the atoms N-I and S; this
localization, a nodal plane between both atoms and the low
energetic state of the LUMO enable optimum interaction
with the highest occupied orbital (HOMO) of the diene in
the sense of a normal Diels-Alder reaction[51.
Evidence for the ‘‘aromaticity”[61of the new heterocyclic
system (2) can begained from its resonance energy. Resonance
energies on an HMO basis have recently been re-defined[’].
For (2) calculation according to this definition yields a distinctly large resonance energy of 0.313 p (for comparison:
naphthalene 0.389 p); the ring system (2) can therefore be
regarded as being heteroaromatic.
Received: August 9, 1977 [ Z 813 IE]
German version: Angew. Chem. 89, 826 (1977)
CAS Registry numbers:
( I ah), 33800-08-7; ( I c ) , 63904-41-6: ( l d ) , 63904-42-7; ( l e ) , 63904-43-8;
( 2 0 ) - 63904-45-0; ( Z h ) , 63904-47-2: ( 2 c ) . 63904-49-4; ( 2 d ) . 63904-51-8;
(Zr), 63904-53-0; 2-amino-5-chlorobenzamide;
5202-85-7; 2-amino-3S-di16313-65-8; N,N‘chlorohenzamide, 36765-01 -2; 2-amino-5-nitrohenzamide,
his(p-toluenesulfony1)sulfur diimide, 851-06-9; trimethyloxonlum tetrafluoroborate, 420-37-1 ; triethyloxonium tetrafluorohorate, 368-39-8; 2,3-dimethylhutadiene, 51 3-81-5;1,3-pentadiene, 504-60-9; isoprene, 78-79-5; 2,3-dimethylbutadiene adduct with ( 2 b ) , 63904-54-1
0. Hinsherg, Ber. Dtsch. Chem. Ges. 22, 2895 (1889).
[ 2 ] H. Grill, G. Krrs:e. Justus Liebigs Ann. Chem. 749, 171 (1971).
[ 3 ] G. A . Olali, J L. Gra,it. J. Am. Chem. Sac. 97, 1546 (1975).
[I]
[4] W Koshuhti. unpublished.
[5] K . N . Houk, Acc. Chem. Res. 8. 361 (1975).
[6] G. Binsch, Naturwissenschaften 60, 369 (1973); G. Muier, Chem. Unserer
Zeit 9. 131 (1975).
[7] J . Aihura, J. Am. Chem. Soc. 98, 2750, 6840 (1976); L. Gurman, M .
Milun, N. Pinuj.$tiC, ihid. 99. 1692 (1977).
cis- and trans-Diazene (Diimine)”]
[*] Dr. hahil. W. Kosbahn, Dr. H. Schafer
Arheitsgemeinschaft fur Strukturchemie der Technischen Universitat
Arcisstr. 21, D-8000 Munchen 2 (Germany)
[**I
This work was supported by the Deutsche Forschungsgemeinschaft
and the Leihniz-Rechenzentrum Miinchen. The results were delivered in
part in a lecture at the Chemiedozententagung in Marburg on March 25,
1977.
780
By Nils Wiberg, Gerd Fischer, and Heinz Bachhnber[*l
According to experimental findings“’ and quantum
mechanical calculations[’] N2H2 can exist in two constitu[*] Prof. Dr. N . Wiberg, Dr. G. Fischer, Dr. H. Bachhuber
lnstitut fur Anorganische Chemie der Universitat
Meiserstr. I . D-8000 Miinchen 2 (Germany)
Angew. Chem. I n t . Ed. Engl. 16 (1977) No. 11
tionally isomeric forms, diazene (diimine) and isodiazene (isodiimine); for the diazene two configurationally isomeric forms
are conceivable. trans- and cis-diazene.
,N="
H
.. .. H
'iN=d
H'
trans-
H\
,N=N
H'
Diazene
cis-
Isodiazene
As shown by mass spectrometric investigations, in the thermolysis of alkali-metal to~ylhydrazides[~J
according to
Tos,
lH
,N-N\
M
H
-TosM
NzHz
two constitutionally isomeric species N2H2I1] are formed
depending upon the nature of M and the pretreatment of
the tosylhydrazide: lithium, sodium, potassium, and aged
cesium tosylhydrazide lead to formation of an energy-poor,
yellow N2H2(diazene), which above ca. - 180°C mainly disproportionates into nitrogen and hydrazine; freshly prepared
cesium tosylhydrazide leads to a colorless NzH2 species (isodiazene) which is richer in energy by about 13 kcal/mol
(54 kJ/mol), readily isomerizes, and decomposes above ca.
-240°C into nitrogen, hydrogen and ammonia. Thermolysis
of rubidium tosylhydrazide affords both sorts of N2H2.
According to IR spectroscopic measurements the energypoorer diazene itself occurs in two configurationally isomeric
forms. Thus, as we have previously observed, in the thermal
decomposition of potassium tosylhydrazide mainly one NzH2
form (cis-diazene) is produced which on contact with cold surfaces transforms into the other form (trans-diazene). If the NzH2
gas is passed through a glass tube cooled with 'dry-ice' ( - 78 "C)
onto an IR window cooled with liquid nitrogen ( - 196°C)
then-according to the TR spectrum-a mixed condensate of
both isomers is obtained which, given a short cooling tube,
chiefly contains cis-diazene, and given a long cooling tube
exists mainly as trans-diazene. The temperature of the window
also plays a role: at lower temperatures the cis-diazene is
obtained, at higher temperatures the trans-diazene.
A typical IR spectrum of the NZH2 mixed condensate,
which generally contains hydrazine14' shows-besides bands
of NzH4 and two further absorptions at 2935 and 287Ocm-'
that are possibly due to hydrogen bridge vibrations-two
groups of bands which according to number and
are evidently due to vibrations of trans- and cis-diazene. The
intensity of the band for the trans isomer increases at the
expense of the absorptions of the cis isomer if a long cooling
tube (up to
and/or a relatively warm IR window[']
is used (the spectrum of a mixed condensate containing mainly
trans-diazene is illustrated in [31), and vice cersa. Should the
changes in the IR spectrum arise merely as a result of differences in molecular aggregation of a configurational isomer
then only the condensation temperature, but not the length
of the cooling tube, could influence the spectrum of the N2Hz
condensate.
I R vibration bands of solid diazene and dideuteriodiarene. The underlined
wave numbers [cm-I] are assigned to the fratis form. the remainder t o
the cis lorm.
NzH2:
N2D2:
3116. 3109. 3025, 1347. 1 3 3 . 1304
2305, 2275. 1517, 1084, 989
Our interpretation of the data is supported by investigations
on dideuteriodiazene, which on the grounds of the kinetic
isotope effect should have a lower reactivity, i.e. a higher
Angew C h i . I t i t .
Ed. E t i g l . 16 ( 1 9 7 7 ) No. 1 1
thermostability and stability towards isomerization. In fact
the thermolysis gas from lithium [Dz]-tosylhydrazide contains
astonishingly little N2D4141;also the low-temperature condensate consists of only one sort of N2Dz, even after flowing
through a longer glass tube cooled to - 78 "C: The IR spectrum
of the condensate shows only one group of relatively sharp
bands, which according to number and position correspond
to the cis form.
The two configurationally isomeric diazenes are distinguishable only on the basis of the IR spectra, but not the
UV or mass spectra. Their electronic structure ought, therefore, to be very similar (cf.1'1 and the almost identical electron
spectrum of trans and cis azomethane[']). Since no difference
in the appearance energies of the molecular and fragment
ions of the isomers can be detected mass spectrometrically
(limit of error: 1.5 kcal/mol) their energy content might
be almost equal. The observed cis-rtrans isomerization would
of course indicate that the trans-diazene is somewhat more
stable than the cis-diazene. This is consistent with calculations['], according to which isodiazene is considerably richer,
but cis-diazene only slightly richer in energy than truns-diazene.
Received: August 4, 1977 [Z 815 IE]
German version: Angew. Chem. 89, 828 (1977)
CAS Registry numbers:
truns-diazene, 15626-43.4; cis-diarene, 15626-42-3; isodiazene, 28647-38-3;
Li tosylhydrazide, 38448-42-9; Na tosylhydrazide, 38448-43-0; K tosylhydraride, 38448-44-1; Cs tosylhydrazide, 63915-1 1-7; R b tosylhydrazlde, 63915-12-
Part 22 of Diimine and Its Derivatives. This work was supported by
the Deutsche Forschungsgemeinschaft.~-Part 21 : N. Wiherg. G. Fischrr,
H. Bachhuhrr,.Angew. Chem. 88. 386 (1976); Angew. Chem. Int. Ed.
Engl. 15, 385 (1976).
R . Ahiriclis, r/: Stummier. Chem. Phys. Lett. 37. 77 (1976); N . C. Baird,
R . F. Burr, Can. J. Chem. 51. 3303 (1973); G. Wiyriihr, Theor. Chim.
Acta 31, 269 (1973).
N . Wiherg, C . Fischrr, H. BuchAuher, Chem. Ber. 107, 1456 (1974).
Owing t o the high decomposibility of diazene the thermolysis gas of
alkali-metal tosylhydrazides always contains the disproportionation
product hydrazine. which can be separated from N2H2 only if the gas
mixture is passed through very long glass tubes cooled with 'dry ice'.
Considering vibration spectroscopic selection rules, 3 IR active absorptions are expected for from-diarene, 5 for cis-diazene.
Because of the decomposibility of diarene the temperature of the I R
window should not exceed - 180°C; also the cooling tube should not
be too long.
R . F . Hiittmi. C . Sterl, J. Am. Chem. Soc. 86. 745 (1964).
a-Oxocarbene-Oxirene Isomerization:
Photolysis of [1-'3C]-2-Diazo-l-phenyl-l-propanone
and [2-'3C]-l-Diazo-l-phenyl-2-propanoneC**]
By Klaus-Peter Zeller"]
The carbene-carbene rearrangement of 3-oxocarbenes via
potential antiaromatic oxirenes"' has been demonstrated on
numerous acyclic systems by carbon labeling[2]or competing
carbene reactions[3? Scheme 1 outlines the individual steps
on using the labeling technique and the Wolff rearrangement
as demonstration reactions.
p]
Priv.-Doz. Dr. K.-P. Zeller
[nstitut fur Organische Chetnie der Universitat
Auf der Morgenstelle 18, D-7400 Tiibingen 1 (Germany)
[**I This work was supported by the Deutsche Forschungsgemeinschaft,
781
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