Chemistry of polyhalogenated nitrobutadienes, 3: [4+2] cycloadditions of (Z)-1,1,4-trichloro-2,4-dinitrobuta-1,3-diene and subsequent reactions

Article abstract of DOI:10.1055/s-2006-956490

The multifaceted chemical behavior of polyhalogenated nitrobutadienes, such as 1 and 2, inspired us to test their features in [4+2] cycloaddition reactions. It appears that in the presence of an appropriate diene only the β-chloro-β-nitro vinyl moiety of

Full text of DOI:10.1055/s-2006-956490

3464
LETTER
Chemistry of Polyhalogenated Nitrobutadienes, 3: [4+2] Cycloadditions of
(Z)-1,1,4-Trichloro-2,4-dinitrobuta-1,3-diene and Subsequent Reactions
C
ycloaddition Rea
i
ctions
k
t
hloro-2
o
,4-dinitrobut
r
a-1,3-diene A. Zapol’skii,a Jan C. Namyslo,a Björn Blaschkowski,b Dieter E. Kaufmann*a
a
Institut für Organische Chemie, Technische Universität Clausthal, Leibnizstraße 6, 38678 Clausthal-Zellerfeld, Germany
Fax +49(5323)722834; E-mail: dieter.kaufmann@tu-clausthal.de
b
Institut für Anorganische und Analytische Chemie, Technische Universität Clausthal, Leibnizstraße 6, 38678 Clausthal-Zellerfeld,
Germany
Received 18 August 2006
activity.5 For example, this is the case for the herbicide
nitrofen6 and the fungicide pentachloronitrobenzene
(Figure 2).
Abstract: The multifaceted chemical behavior of polyhalogenated
nitrobutadienes, such as 1 and 2, inspired us to test their features in
[4+2] cycloaddition reactions. It appears that in the presence of an
appropriate diene only the b-chloro-b-nitro vinyl moiety of 1 acts as
an efficient dienophile. The resulting cycloaddition products were
subsequently converted at the b,b-dichloro position by means of a
suitable N,O- and N,N-bisnucleophile to give benzoxazole or benz-
imidazole derivatives. The latter reaction products proved valuable
for crop protection.
Cl
Cl
Cl
O
Cl
Cl
Cl
Cl
Cl
N
S
Cl
Cl
O
Key words: nitro compound, haloalkene, cycloaddition, Diels–Al-
der, heterocycle
aldrin
O
captafol
Cl
Cl
Cl
Cl
Cl
Cl
Nitro-substituted polyhalogenobuta-1,3-dienes are mem-
bers of a rather new class of organic compounds which be-
came the topic of recent investigations due to interesting
chemical characteristics as well as biological properties.1,2
Among these, (Z)-1,1,4-trichloro-2,4-dinitrobuta-1,3-di-
ene (1) is less easily accessible than 2; it was prepared for
the first time in 1993 by means of nitration of 1-bromo-
1,4,4-trichlorobuta-1,3-diene.3 However, its chemical
properties are hitherto fairly unexplored, in contrast to, for
O2N
Cl
NO2
nitrofen
pentachloro-
nitrobenzene
Figure 2 Pesticides based on chlorinated compounds
Moreover, with the new Diels–Alder products in hand,
we subsequently took advantage of the high reactivity
of the remaining dichloro-substituted olefinic carbon.
Thus, by reaction of this electron-deficient center with an
appropriate aromatic N,O- or N,N-bisnucleophile (e.g. 2-
aminohydroxy- or 1,2-diaminobenzene), interesting benz-
oxazole or benzimidazole derivatives were synthesized
which are currently under biological screening.
example,
pentachloro-2-nitrobuta-1,3-diene
(2,
Figure 1).4
Cl
Cl
Cl
O2N
Cl
Cl
Cl
Cl
NO2
Cl
NO2
1
2
In detail, our investigations started with the synthesis of
(Z)-1,1,4-trichloro-2,4-dinitrobuta-1,3-diene (1) which
was obtained in four steps from 1,2-dichloroethylene
(Scheme 1).3
Figure 1 Nitro-substituted polyhalogenobuta-1,3-dienes
In the present paper we mainly focus on (Z)-1,1,4-trichlo-
ro-2,4-dinitrobuta-1,3-diene (1) as a novel dienophile for
Diels–Alder reactions. The resulting cycloadducts serve
as useful precursors for the synthesis of physiologically
active substances, for example pesticides, as evidenced by
the structural formula of potent agents like aldrin or
captafol (Figure 1) that are similarly accessible by [4+2]
cycloadditions. In almost the same manner as it is known
from these highly chlorinated compounds, the additional
presence of a nitro substituent enforces the biological
Cl
Br
Br
Cl
Cl
Cl
(PhCOO)2
Br2
Cl
Cl
Cl
Cl
Cl
Cl
KOH
(PTC)
HNO3
H3PO4
Br
Cl
O2N
Cl
Cl
Cl
Cl
Cl
O2N
1
SYNLETT 2006, No. 20, pp 3464–3468
Advanced online publication: 08.12.2006
1
8
.1
2
.2
0
0
6
Scheme 1
DOI: 10.1055/s-2006-956490; Art ID: G27206ST
© Georg Thieme Verlag Stuttgart · New York

LETTER
Cycloaddition Reactions of 1,1,4-Trichloro-2,4-dinitrobuta-1,3-diene
3465
1
The first synthetic step is the radical dimerization of 1,2- mixture of regioisomers (3:1 ratio as evidenced by H
dichloroethylene producing a mixture of isomers. The re- NMR), albeit in low yield (25%). Addition of hydroquino-
sulting 1,3,4,4-tetrachlorobut-1-ene then is brominated. ne could not prevent polymerization of 3. An increased
Subsequent twofold dehydrobromination by means of po- yield (37%) was obtained in the case of diene 4 under sim-
tassium hydroxide under phase-transfer-catalysis condi- ilar conditions (65–70 °C, 40 h), whereupon in a regiose-
tions, followed by nitration of the intermediate lective manner the dimethylcyclohexene 7 was formed.
bromobuta-1,3-diene, gave the desired trichloro-dinitro- Attempted cycloadditions with 1-methoxy-1,3-butadiene
diene 1. In general, cycloaddition reactions of unsaturated or 1-methoxy-3-trimethylsiloxybuta-1,3-diene (Danishef-
nitrohalo compounds are fairly rare in the literature. sky’s diene) led to the formation of polymers exclusively
Among these, some examples are known with halonitro- or predominantly. Best results were achieved with cyclo-
ethylenes.7 To the best of our knowledge, cycloadditions pentadiene (5) applying very mild conditions (20 °C, 96
with polyhalogenated nitrobuta-1,3-dienes are unknown h). The expected bicyclic stereoisomer 8 was diastereo-
up to now. However, the less substituted 2,3-dichlorobu- selectively synthesized this way in 60% yield. The similar
ta-1,3-diene as well as the 1,4-dichloro isomer act as a di- reaction of the dinitrobutadiene 1 with cyclohexa-1,3-
ene in Diels–Alder reactions, whereas both, the 1,1,2- and diene unexpectedly delivered a complex mixture of
1,2,3-trichloro derivatives are good dienophiles.8 In con- products that could not be separated by column
junction with this work we became interested in the cy- chromatography. All attempts to force 1 as well as 2 to re-
cloaddition modes of (Z)-1,1,4-trichloro-2,4-dinitrobuta- act as a diene with dienophiles such as ethylenetetracarbo-
1,3-diene (1) and perchloro-2-nitrobuta-1,3-diene (2). By nitrile, acrylonitrile, ethyl acrylate, 3-bromoprop-1-ene,
means of X-ray analysis it had been confirmed that in the 2-methylbut-2-ene, or styrene remained unsuccessful.
solid state these nitrodienes exist in an s-trans form,9 due
to their bulky substituents. In our experiments, nitrodiene
1 exclusively acted as a dienophile, whereas reactive
From a mechanistic viewpoint it is interesting to know,
that even though the a-nitro-b,b-dichloro vinyl moiety
within 1 is even more electron-deficient, only the b-chlo-
dienes such as isoprene (3), 2,3-dimethylbuta-1,3-diene
ro-b-nitro vinyl group undergoes the [4+2] cycloaddition
(4), cyclopentadiene (5), or cyclohexa-1,3-diene under-
as the dienophile, probably due to a lower sterical de-
mand. Additional synthetic examples illustrate the chem-
took the task of the diene (Scheme 2).
For example, diene 1 reacts with a fivefold excess of iso- ical behavior of this unusual disubstituted vinyl group
prene (3) in a sealed ampule at 80–85 °C within 60 hours such as the selective reduction of the C=C double bond by
to give the cyclohexene derivatives 6a,b as an inseparable means either of sodium borohydride10a or with molecular
hydrogen and palladium on charcoal,10b in both cases
leaving the chloro as well as the nitro substituent un-
changed. Furthermore, interesting condensation reactions
Cl
Cl
have been published to give highly substituted 2H-1-
NO2
benzopyranes,10c–f furo[3,2-c]pyran-4-ones,10g furo[2,3-
d]pyrimidin-4(3H)-ones,10h,i anthracene-9,10-diones,10j
NO2
6a
(25%)
furans, tetrahydro-4(2H)benzofuranones, and ana-
logues,10k or chromane derivatives.10g,l,m In addition, the
formation of 4-oxospiro[2.5]octanes10n is worth mention-
ing. Other synthetic strategies using the b-chloro-b-nitro
vinyl group, involve the cyclization with ethane-1,1,2,2-
tetracarbonitrile to give a hepta-substituted cyclopen-
tene,10o use the formation of a substituted isoxazole10p or
create a 5,6-dihydro-4H-[1,2]oxazine N-oxide.10q More-
over, addition reactions of arylsulfinic acid derivatives
have been pointed out.10r,s Last, but not least in this con-
text, the rare vinylic substitution of the nitro group of this
b-chloro-b-nitro vinyl fragment 1 has been demonstrated
by using 1H-benzotriazole or butanethiol as the nucleo-
phile.11,12
Cl
3
(3:1 ratio)
Cl
Cl
NO2
NO2
6b
Cl
Cl
Cl
O2N
Cl
NO2
NO2
Cl
Cl
4
O2N
7 (37%)
However, all attempts to use pentachloro-2-nitrobuta-1,3-
diene (2) as the dienophile along with the dienes 3–5
failed, regardless of the presence or absence of a Lewis
acid such as zinc dichloride, lithium chloride, or alumi-
num trichloride. Either no conversion or polymerization
was observed, even though hydroquinone had been added.
Solely the combination of aluminum trichloride and cy-
clopentadiene (5) gave an inseparable mixture of cycload-
dition products. Despite this unwanted behavior, it is well
Cl
1
Cl
Cl
5
NO2
Cl
NO2
8 (60%)
Scheme 2
Synlett 2006, No. 20, 3464–3468 © Thieme Stuttgart · New York

3466
V. A. Zapol’skii et al.
LETTER
known that the trichlorovinyl group in 2 generally allows
for rich chemistry, e.g. halogenations,13a,b epoxidations,13c
saponification,13d or other types of addition reactions.13d–h
But cycloadditions, predominantly of the [2+2]-type, with
this trichlorovinyl double bond taking part, need harsh
conditions: among these, irradiations,14a–d high-tempera-
ture reactions,14e or the application of Friedel–Crafts-type
catalysts14f have been published. As a tentative result, the
lower reactivity of the perchlorinated nitrodiene 2 in
general compared to the title compound 1 may be due to
the distinct steric hindrance caused by a total of five
chloro substituents. The a-nitro-b,b-dichloro vinyl group
within these molecules exhibits no reactivity towards
cycloaddition reactions, whereas its tendency to undergo
vinylic SN reactions exceeds the reactivity of both the
b-chloro-b-nitro vinyl group of 1 and the trichloro vinyl
Figure
3
X-ray structure of 2-exo-[(3-exo-chloro-3-nitrobi-
cyclo[2.2.1]hept-5-en-2-yl)nitromethyl]benzooxazole (9)15
group within the pentachloro compound 2, with respect to In conclusion, the b-chloro-b-nitro vinyl moiety within
such vinylic substitution reactions.
(Z)-1,1,4-trichloro-2,4-dinitrobuta-1,3-diene (1) acts as
an efficient dienophile in [4+2]-cycloaddition reactions
with classical electron-rich dienes, whereas the additional
a-nitro-b,b-dichloro vinyl group shows no such reactivity
with respect to Diels–Alder reactions. However, the latter
vinyl group offers great potential in vinylic substitution of
the two chloro substituents, due to the activating a-nitro
group. Thus, the Diels–Alder products were subsequently
reacted with appropriate aromatic N,O- or N,N-bisnucleo-
philes. The resulting benzoxazole or benzimidazole deriv-
atives show promising physiological activity, probably as
candidates for application as pesticides. Further biological
testing is underway.
In addition, the highly substituted Diels–Alder products
6–8 turned out to be promising substrates for a subsequent
vinylic substitution with appropriate nucleophiles, in fact
at the terminal carbon atom of the remaining a-nitro-b,b-
dichloro moiety. By means of o-aminophenol or o-phen-
ylenediamine, the twofold vinylic SN reaction of 8
afforded the benzoxazole 9 in 85% yield or benzimidazole
10 in 80% yield, respectively. As it is known from such
a-nitro-b,b-dichloro compounds, these reactions involve
the formation of intermediate 2,3-dihydro derivatives
which subsequently aromatize to give the heterocycles 9
and 10 (Scheme 3).
Acknowledgment
We gratefully acknowledge BAYER AG, Leverkusen, for financial
support and CHEMETALL GmbH, Frankfurt am Main, for chemi-
cals. We are indebted to Dr. H. Frauendorf, Universität Göttingen,
for HRMS data.
NH2
N
O
OH
NO2
Cl
NO2
References and Notes
Cl
Cl
9 (85%)
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NO2
Cl
NO2
N
8
NH
NH2
NH2
NO2
Cl
NO2
10 (80%)
Scheme 3
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(Figure 3). This way we are able to proof the conservation
of the stereochemistry of 1 unambiguously, with the big
heterocyclic substituent in an exo-position.
Synlett 2006, No. 20, 3464–3468 © Thieme Stuttgart · New York

LETTER
Cycloaddition Reactions of 1,1,4-Trichloro-2,4-dinitrobuta-1,3-diene
3467
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electron density = 0.203 and –0.267 e Å–3. CCDC 278475
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Melting points were measured on a Büchi 520 apparatus and
were uncorrected. 1H NMR, 13C NMR, 14N NMR, and 15
N
NMR spectra were obtained on a Bruker Avance with 400
MHz proton frequency, 15N NMR were measured in inverse
2D mode (gs-HMBC). 1H NMR spectra in CDCl3 were
referenced to tetramethylsilane (TMS) at d = 0.0 ppm; 13
C
NMR spectra refer to the solvent signal center at d = 77.0
ppm. Other solvents as follows: DMSO-d6: 2.50 ppm (1H),
39.70 ppm (13C); (CD3)2CO: 2.04 ppm (1H), 29.8 ppm (13C),
C6D6: 7.20 ppm (1H), 128.0 ppm (13C). N NMR spectra were
externally referenced to nitromethane at d = 0.0 ppm. IR
spectra were obtained on a Bruker ‘Vector 22’ FT IR as KBr
IR. Mass spectra were recorded on a Hewlett Packard system
‘MS 5989B’ with direct inlet. All masses of chlorine
containing molecules or fragments refer to the isotope 35Cl.
High-resolution mass spectra were measured with a Varian
MAT 311 A spectrometer with pre-selected molecular ion
peak matching at R >> 10000 to be within 2 ppm of the
exact masses. Elemental analyses were performed by Institut
für Pharmazeutische Chemie, TU Braunschweig. TLC was
carried out on Merck plates coated with silica gel (60 F 254).
Silica gel 60 was also used for column chromatography.
(Z)-1,1,4-Trichloro-2,4-dinitro-1,3-butadiene (1).3
Yellow solid, mp 70–71 °C. 1H NMR (CDCl3): d = 8.12 (s,
1 H). 13C NMR (CDCl3): d = 142.6 (C-4), 141.5 (C-2), 135.7
(C-1), 118.1 (C-3). 15N NMR (CDCl3): d = –20.5, –21.4.
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nitrovinyl)-2-methyl-5-nitrocyclohex-1-ene (6b).
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An ampule was charged with 0.50 g (2.00 mmol)
dinitrodiene 1, 0.68 g (10.0 mmol) isoprene (3), and 10 mg
(0.1 mmol) hydroquinone and sealed. The mixture was
stirred under N2 atmosphere for 60 h at 80–85 °C. After
extraction thrice with PE–Et2O (3:1) and separation of poly-
meric by-product, the solvent and residual volatiles were
evaporated in vacuo. The crude product was purified by
column chromatography with PE as the eluent. Yield 0.16 g
(25%) of 6a,b, mp 118–119 °C. Isomeric ratio 6a/6b = 3:1.
IR (KBr): 2937, 2915, 1618 (C=C), 1566 (NO2), 1543
(NO2), 1442, 1430, 1364 (NO2), 1350 (NO2), 1054, 1021,
978, 935, 843, 774, 706, 643, 588 cm–1. 1H NMR (CDCl3):
d (major isomer) = 1.73 (s, 3 H, CH3), 2.52 (m, 1 H, CH2),
2.70 (m, 1 H, CH2), 2.92 (m, 1 H, CH2), 3.27 (m, 1 H, CH2),
4.48 (dd, 3J = 8.5, 6.0 Hz, 1 H, H-5), 5.31 (m, 1 H, -CH=);
d (minor isomer) = 1.72 (s, 3 H, CH3), 2.42 (m, 1 H, CH2),
(15) Crystal Data for 9.
C15H12ClN3O5, M = 349.73 g mol–1, crystal size 0.2 × 0.2 ×
0.5 mm were collected on a Stoe IPDS II diffractometer
using l = 0.71073 Å [T = 223(2) K]. The crystal structure
Synlett 2006, No. 20, 3464–3468 © Thieme Stuttgart · New York

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V. A. Zapol’skii et al.
LETTER
+
2.65 (m, 1 H, CH2), 2.85 (m, 1 H, CH2), 3.35 (m, 1 H, CH2),
4.39 (dd, 3J = 8.3, 5.8 Hz, 1 H, H-4), 5.43 (m, 1 H, -CH=).
13C NMR (CDCl3): d (major isomer) = 22.59 (CH3), 32.58
(CH2), 40.73 (CH2), 44.26 (-CH-), 102.42 [C(NO2)Cl],
115.84 (CH=), 127.84 (=CCl2), 132.54 (=C-Me), 146.73
[=C(NO2)]; d (minor isomer) = 22.47 (CH3), 27.98 (CH2),
43.88 (CH), 44.80 (CH2), 102.67 [C(NO2)Cl], 118.45
(CH=), 127.81 (=CCl2), 129.74 (=C–Me), 146.77
m/z (%) = 266 (2) [M – NO2 ], 219 (13), 183 (38), 149 (73),
136 (21), 115 (34), 66 (100). HRMS (EI) [M+]: m/z calcd for
C9H7Cl3N2O4: 311.9471.
2-exo-{(3-exo-Chloro-3-nitrobicyclo[2.2.1]hept-5-en-2-
yl)nitromethyl}benzoxazole (9).
To a suspension of 0.40 g (1.28 mmol) bicycloheptene 8 in
10 mL MeOH was added a solution of 0.46 g (4.23 mmol) o-
aminophenol in 20 mL MeOH at 0 °C within 10 min. The
mixture was kept at 0–10 °C for 1 h, then 4 h at r.t. After
addition of 10 drops of concd HCl and 1 h at r.t., the mixture
was cooled down to 0 °C. The precipitate was sucked off,
washed thrice with H2O and once with 10 mL of cold MeOH.
Drying in vacuo yielded 0.38 g (85%) of benzoxazole 9, mp
165–167 °C. IR (KBr): 3018, 1611, 1568 (NO2), 1557
(NO2), 1481, 1451, 1353 (NO2), 1232, 1173, 1067, 1003,
977, 950, 912, 879, 805, 784, 760, 749, 732, 687, 574, 513
cm–1. 1H NMR (CD3COCD3): d = 1.92 (ddd, J = 10.3, 4.2,
2.1 Hz, 1 H, H-7syn), 2.43 (d, 1 H, H-7anti, 2J = 10.3 Hz), 2.88
(m, 1 H, H-1), 3.70 (m, 1 H, H-4), 4.35 (dd, J = 11.5, 2.1 Hz,
1 H, H-2), 6.09 (dd, J = 5.6, 3.1 Hz, 1 H, H-5), 6.48 [d,
J = 11.5 Hz, 1 H, -CH(NO2)], 6.66 (dd, J = 5.6, 3.1 Hz, 1 H,
H-6), 7.50 (ddd, J = 7.8, 7.5, 1.2 Hz, 1 H, Haryl,), 7.56 (ddd,
J = 8.1, 7.5, 1.4 Hz, 1 H, Haryl), 7.78 (ddd, J = 8.1, 1.2, 0.7
[=C(NO2)]. MS (GC-MS, EI): m/z (%) = 314 (3) [M+], 297
(2), 267 (7), 250 (14), 221 (17), 185 (45), 149 (60), 125 (35),
115 (100). Anal. Calcd for C9H9Cl3N2O4 (315.54): C, 34.26;
H, 2.87; N, 8.88. Found: C, 34.49; H, 2.91; N, 8.49.
4-Chloro-5-(2,2-dichloro-1-nitrovinyl)-1,2-dimethyl-4-
nitrocyclohex-1-ene (7).
Preparation as described for 6a,b, except for reaction
conditions: 65–70 °C, 40 h. Yield 37%, mp 84–85 °C. IR
(KBr): 2922, 1619 (C=C), 1562 (NO2), 1541 (NO2), 1433,
1368 (NO2), 1352 (NO2), 1252, 1061, 953, 852, 810, 778,
637 cm–1. 1H NMR (CDCl3): d = 1.65 (br s, 6 H, 2 CH3), 2.46
(dd, 2J = 17.8 Hz, 3J = 5.8 Hz, 1 H, H-6), 2.64 (dd, 2J = 17.8
Hz, 3J = 8.1 Hz, 1 H, H-6), 2.80 (d, 2J = 17.6 Hz, 1 H, H-3),
3.27 (d, 2J = 17.6 Hz, 1 H, H-3), 4.44 (dd, 3J = 8.1, 5.8 Hz, 1
H, H-5). 13C NMR (CDCl3): d = 18.2 (CH3), 18.3 (CH3),
33.6 (C-6), 44.3 (C-5), 45.6 (C-3), 102.6 (C-4), 121.7 (=C–
Me), 124.0 (=C–Me), 127.7 (=CCl2), 146.8 [=C(NO2)]. MS
(direct inlet): m/z (%) = 328 (2) [M+], 313 (1), 298 (2), 281
(9), 264 (8), 246 (6), 235 (27), 199 (33), 164 (34), 139 (19),
129 (41), 105 (36), 43 (100). Anal. Calcd for C10H11Cl3N2O4
(329.57): C, 36.44; H, 3.36; N, 8.50. Found: C, 36.60; H,
3.33; N, 8.22.
Hz, 1 H, Haryl), 7.86 (ddd, J = 7.8, 1.4, 0.7 Hz, 1 H, Haryl). 13
C
NMR (CD3COCD3): d = 46.9 (C-1), 47.6 (C-7), 50.4 (C-2),
60.1 (C-4), 85.8 [-CH(NO2)], 109.7 (C-3), 112.2 (Caryl),
121.8 (Caryl), 126.4 (Caryl), 128.0 (Caryl), 133.4 (C-5), 141.2
(Cquat.,aryl), 142.9 (C-6), 151.7 (Cquat.,aryl), 158.2 (C=N). MS:
+
m/z (%) = 304 (2) [M – NO2 ], 273 (32), 256 (10), 238 (100),
220 (58), 204 (47), 191 (50). HRMS (EI) [M+]: m/z calcd for
2-exo-Chloro-3-exo-(2,2-dichloro-1-nitrovinyl)-2-endo-
nitrobicyclo[2.2.1]hept-5-ene (8).
C15H12ClN3O5: 349.0465.15
2-exo-{(3-exo-Chloro-3-nitrobicyclo[2.2.1]hept-5-en-2-
yl)nitromethyl}-1H-benzimidazole (10).
Procedure: 0.50 g (2.0 mmol) dinitrodiene 1 and 1.32 g (20
mmol) cyclopentadiene (5) were stirred for 4 d at r.t.
Subsequently, the mixture was cooled down to 0 °C. The
precipitated crude product was filtered off and recrystallized
from PE–Et2O (1:1). Yield 0.38 g (60%), mp 119–120 °C.
IR (KBr): 3082, 3013, 2975, 2888, 1608, 1575 (NO2), 1535
(NO2), 1458, 1360 (NO2), 1338 (NO2), 1254, 1172, 1065,
987, 971, 950, 888, 808, 767, 703, 676, 645, 591, 544 cm–1.
1H NMR (CDCl3): d = 1.93 (s, 2 H, CH2), 3.38 (s, 1 H, H-4),
3.60 (s, 1 H, H-1), 4.31 (s, 1 H, H-3), 6.07 (br s, 1 H, H-6),
6.56 (br s, 1 H, H-5). 1H NMR (C6D6): d = 1.25 (d, 2J = 10.7
Hz, 1 H, H-7syn,), 1.70 (d, 2J = 10.7 Hz, 1 H, H-7anti), 2.79 (m,
1 H, H-4), 3.10 (br s, 1 H, H-1), 3.98 (d, 3J = 2.1 Hz, 1 H, H-
3), 5.50 (dd, 3J = 5.5, 3.2 Hz, 1 H, H-6), 5.71 (dd, 3J = 5.5,
3.2 Hz, 1 H, H-5). 13C NMR (CDCl3): d = 46.6 (C-3), 47.2
(CH2), 50.8 (C-4), 56.6 (C-1), 108.4 (C-2), 128.8 (=CCl2),
134.5 (C-6), 141.3 (C-5), 148.1 [=C(NO2)]. MS (GC-MS):
Prepared in analogy to compound 9 from bicycloheptene 8
and o-phenylenediamine (ratio 1:2.2), yield 80%, mp 105–
107 °C. IR (KBr): 3385, 2998, 1621 (C=C), 1561 (NO2),
1456, 1430, 1346 (NO2), 1231, 1149, 1061, 958, 906, 840,
784, 749, 616, 578, 439 cm–1. 1H NMR (CD3COCD3):
d = 1.85 (dd, J = 10.2, 2.1 Hz, 1 H, H-7syn), 2.34 (d, 2J = 10.2
Hz, 1 H, H-7anti), 2.64 (m, 1 H, H-1), 3.66 (m, 1 H, H-4), 4.49
(m, 1 H, H-2), 6.06 (dd, J = 5.6, 3.0 Hz, 1 H, H-5), 6.39 [d,
J = 11.6 Hz, 1 H, -CH(NO2)], 6.62 (dd, J = 5.6, 3.0 Hz, 1 H,
H-6), 7.36 (m, 2 H, Haryl), 7.72 (m, 2 H, Haryl). 13C NMR
(CD3COCD3): d = 47.0 (C-1), 47.7 (CH2), 50.6 (C-2), 60.1
(C-4), 86.0 [-CH(NO2)], 110.1 (C-3), 116.8 (2 C, Caryl),
124.8 (2 C, Caryl), 133.2 (C-5), 138.4 (2 C, Cquat.,aryl), 143.0
(C-6), 146.1 (C=N). MS: m/z (%) = 348 (2) [M+], 302 (34),
287 (12), 272 (35), 255 (15), 237 (100), 219 (92). HRMS
(EI) [M+]: m/z calcd for C15H13ClN4O4: 348.0625.
Synlett 2006, No. 20, 3464–3468 © Thieme Stuttgart · New York