Azulene-1-azo-2′-thiazoles. Synthesis and Properties

Article abstract of DOI:10.1002/jhet.5570400607

Several derivatives belonging to a new compound class, namely azulene-1-azo-2′-thiazoles, were prepared by the diazotization of 2-aminothiazoles in the presence of HNO₃/H₃PO₄ followed by the coupling of diazonium salts wit

Full text of DOI:10.1002/jhet.5570400607

a
995
Nov-Dec 2003
Azulene-1-azo-2'-thiazoles. Synthesis and Properties
b
Alexandru C. Razus, Liviu Birzan, Stefania Nae, Mirela Nina Surugiu
and Valentin Cimpeanu
Institute of Organic Chemistry, Spl. Independentei 202B, P.O. Box 15-254
060032-Bucharest, Romania
Received July 1, 2003
Several derivatives belonging to a new compound class, namely azulene-1-azo-2'-thiazoles, were pre-
pared by the diazotization of 2-aminothiazoles in the presence of HNO /H PO followed by the coupling of
3
3
4
diazonium salts with azulenes in buffered medium. The reactions proved to be general for this class, the
yields are, however, considerably influenced by the substituents at thiazole moiety. For the first time a N-
oxide provided from an amino substituted five-member nitrogenous heterocycle was diazotized and coupled.
The structure of the obtained compounds was assigned and their physico-chemical properties were dis-
cussed. The new azulene azo derivatives exhibit a strong bathochromic shift in UV-Vis due to the intense
push-pull effect of aromatic system and to the intrinsic properties of thiazole moiety.
J. Heterocyclic Chem., 40, 995 (2003).
Introduction.
As a part of our continuing interest in the study of syn-
thesis and properties of azulene-1-azoaromatics we have
recently investigated the azulene-1-azopyridines deriva-
tives, 1 [1]. Besides the interesting structure and properties
of such compounds, it was anticipated that they possess
high β hyperpolarizability [2] therefore they can be attrac-
tive in the development of various technical fields as dyes
and pigments and in the display, storage or transmission of
information. Another applicability of azulene-1-azopy-
ridines can be found in electrochemistry, for the generation
of an electrically conducting polymer film at the electrode
surface [3].
Az-N=N-Py
1
Although the first thiazolamines diazotization followed
by azo coupling was already reported in the 19 century
th
Az = unsubstituted or substituted azulen-1-yl
Py = 2-, 3- or 4 piridyl group, unsubstituted or N-substituted
[7], some difficulties arose from the low basicity of the
thiazolamines or from the possible diazotization reversibil-
ity in thermodynamic conditions followed by the nitrosa-
tion of coupling substrate [8] (azulene in our case).
Therefore, we tried to generate the azulene-1-azo-2'-thia-
zoles in a similar way as for the corresponding pyridine
derivatives [1a].
The diazotization was carried out in a mixture of phos-
phoric and nitric acids using solid sodium nitrite and the
coupling with azulenes was performed in methanol (potas-
sium acetate was used as buffer for a pH about 4-5)
(Scheme 1). When groups with small inductive or elec-
tromer effect (e.g. halogen) were substituted at C-5 in
2-aminothiazoles, the yield in azo product was almost
quantitative (Scheme 1); the yield was lower for the strong
The similarity between the electronic distributions over
the pyridine and thiazole systems prompted us to investi-
gate the synthesis and some chemical and optical proper-
ties of the new class of azulene-1-azo-2'-thiazole deriva-
tives. Other arguments for our study were the theoretical
[4] and experimental works [5,6] which revealed the high
β hyperpolarizability for 2-vinyl or 2-azo-thiazoles substi-
tuted with NO at C-5.
2
Synthesis of Azulen-1-azo-2'-thiazoles and their 3'-Oxo
derivatives.
A. Azulen-1-azo-2'-thiazoles.
For our study we have chosen the 2-azothiazole deriva-
tives unsubstituted or with different substituents at 5 posi-
tion provided from stable and accessible corresponding
2-aminothiazoles. Due to increased thiazole stability
induced by the phenyl substituted at C-4 these derivatives
were also included in this study.
electron withdrawing functions (e.g. NO or SCN).
2
Starting from the 2SCN, together with the normal coupled
azo derivative 5SCN, disulfide 6 (Scheme 2) resulted in
lower yield as a by-product [9]. Using the azo compounds
4pCH C H N , the double coupled compound
3
6
4
2

996
A. C. Razus, L. Birzan, S. Nae, M. N. Surugiu and V. Cimpeanu
Vol. 40
Scheme 4
5pCH C H N was obtained in reduced yield together
3
6 4 2
with traces of azo derivative 9.
The reaction of the diazonium salt 3I with azulene does
not afford the normal azo products as, for example, in the
coupling with phenols [10]; three other products were sepa-
rated and identified, namely, 1-iodoazulene, 10I (Scheme 4),
1,3-diiodoazulene [11] and the iodinated azo derivative 7, in
80 %, 15 % and <5 % yields, respectively (Scheme 2).
(Scheme 3). The conversion and the yield of diazotization
and coupling are dramatically lower for alkylated azulenes
as compared to unsubstituted azulene, possibly, due to the
steric influence and to the low stability of some alkylazu-
lenes (e.g. guajazulene, 16).
Our attempt to obtain the double coupled thiazole 22
through tandem diazotization of 12 and coupling with azu-
lene, the transfer of a very good electrophilic leaving
group, p-tolylazo, from the 5-position with the higher elec-
tron density in thiazole toward the nucleophilic1-position
in azulene was observed. The generation of azo azulene, 9
[15] (8 %), and of the compound without substituent at
C-5 in thiazole, 17 (15 %), together with the product 22
(5 %), attest this transfer. There are not arguments to dif-
ferentiate between the intermolecular (a + b in Scheme 4)
or intramolecular route (c + d) of this transfer. The pres-
In the attempt to synthesize 5I, 2-aminothiazole was
chloromercuriated at C-5, then diazotised and coupled
with azulene. The obtained crude product was treated with
iodine in excess for the substitution of HgCl group. Even
in this case the compound 5I was not formed and only the
iodo derivatives 7 and 8 were obtained [12].
ence of compound 9 at the generation of 5pCH C H N
3
6 4 2
from the corresponding amine as well as the presence of
the iodinated azulenes at the reaction of 2I can be consid-
ered as indications of the generality of this transfer ability.
B. Azulene-1-azo-2'-(3'-oxy-4'-phenylthiazoles).
To the best of our knowledge, no five-atom nitrogenous
heterocyclic amine has been diazotized and azo coupled
when the cyclic nitrogen was bounded up with oxygen as
N-oxide. Indeed, although 1-oxy-(aminopyridines) are
easily diazotized and coupled in aqueous hydrochloric
solutions [1c], only tar is obtained with 3-oxy-2-aminoth-
iazoles. Unlike pyridine N-oxides, 3-oxy-2-aminothiazoles
are acid sensitive and have a high water solubility that cre-
ates difficulties for their synthesis [16] and for use in dia-
zotization + coupling reactions.
The reaction of 4-phenyl substituted thiazolamine 11 with
nitrous acid generally occurs with nitrozation at C-5 [13].
The cyclic nitrogen phosphorylation in a strong acidic
medium (as in Scheme 1 for compound 3R) lowers the elec-
+
tron density at the nucleus directing the NO attack towards
the amino group [14] therefore, under the conditions we
used, the yields of azo compounds were fairly good
The above-mentioned inconveniences were avoided by
using a more stable and soluble compound in organic media,

Nov-Dec 2003
Azulene-1-azo-2'-thiazoles. Synthesis and Properties
997
such as 2-amino-3-oxy-4-phenylthiazole, (Scheme 5) 23 [17].
Although compound 23 cannot be diazotized and cou-
pled with azulenes in aqueous media, the reaction occurs
in a mixture of concentrated phosphoric and nitric acid. It
is possible that the high reaction rate in strong acidic
medium hinders the extensive destruction of amine before
diazotization. It is puzzling that the yellow-brown color of
the diazonium salt solution turns white after a short time,
however, the coupling capacity remains unaltered. An
explanation for this behavior could be the reversible ring
closing of diazonium salt, 24A to the intermediate 24B
(Scheme 5) [18]. The obtained blue-violet colored azo
derivatives 25 – 27 are stable at room temperature. The
comparison between the yields of the diazotization and
coupling of the aminothiazole and their corresponding 3-
oxide is, generally, in favor of the N-oxide. This described
tandem diazotization + coupling represents the first known
example, which starts from five-atom nitrogenous hetero-
cyclic amine with N-oxy group at the ring, opening a way
for the generation of other derivatives with interesting
properties.
although in the last case substitution at C-5 cannot be a
priori ruled out. The reactions of azulene-1-azo-2'-thia-
zoles reported here, namely, alkylation with methyl iodide,
bromination, chlorination and the reaction with lead thio-
cyanate, evolve in good agreement with the theoretical
anticipation.
The N-alkylation of thiazole derivatives, yielding sta-
ble compounds that can be used as dyes, is well known
[21] however the reported reaction conditions are too
severe for the azulene moiety and the characterization
and the yields of the products are often absent. To avoid
the destruction of azulene moiety during the methylation
we used methyl iodide in chloroform at reflux
Scheme 6
Reactions of Azulene-1-azo-2'-thiazoles.
Based on computational studies [19,20], for 2-substi-
tuted thiazole derivatives, the nitrogen is expected to pos-
sess the highest negative charge, the next reactive position
being at C-5. At the same time, it is known that the azulene
moiety is very reactive in orbital controlled reactions due
to the presence of a high energy HOMO. Thus, it is
expected that hard electrophiles, able to form strong bonds
with nitrogen atoms (e.g. CH I), will react at the thiazolic
3
nitrogen. In contrast, soft electrophiles, without affinity for
nitrogen (e.g. Br ) should react at the azulene moiety,
2

998
A. C. Razus, L. Birzan, S. Nae, M. N. Surugiu and V. Cimpeanu
Vol. 40
(Scheme 6). Even in these conditions, the alkylation of
thiazole derivatives took place with lower conversions
and yields than those for the corresponding azulene-1-
azopyridines. The stability of the C-N bond is sufficiently
high [22] to ensure the conservation of the obtained
kinetic product by avoiding the rearrangements.
The large π and p conjugated electronic system present
in the studied neutral azo derivatives can promote different
charge distributions depending on the external influence
and, as a consequence, different dipole values provided by
the possible resonance structures. This fact is well
reflected in the solvatochromic effect for azulene-1-azo-2'-
thiazoles represented in Table 3. Increasing the solvent
polarity, structures with long-range placed charges (as in
As expected, bromination with N-bromosuccinimide,
chlorination with a mixture of KClO /HCl and the reaction
3
Scheme 7 structure 5NO B) gain in importance inducing a
with lead thiocyanate take place in good yields at C-3 of
azulene moiety (Scheme 6). If the reactant is in excess,
subsequent attack to the C-5 in thiazole can also occur,
confirming the reactivity sequence of these two positions.
The tendency of azulenes to form a complex with iodine
hinders the direct iodination. Therefore the azo compound
was halo-mercurated with mercury acetate followed by in
situ iodine treatment with the generation of mono- and
diiodinated compounds, 7 and 8.
2
bathochromic effect. For example, at the solvent change
from the cyclohexane to dimethylformamide, the value of
∆λ
for the main visible band reaches 61 nm for 5NO
max
2
as compared with only 31 nm for 5H (Table 3). The very
small solvatochromic effect of corresponding N-oxides
reflects the intrinsic polarization of their molecules. The
solvatochromic effect is absent, however, for N-alkylated
salt, 28, where the positive charge is already spread includ-
3
ing the tropylium structure for azulene moiety and the sp
Optical Properties of Azo-thiazols.
hybridization for thiazole nitrogen.
From the heterocycle possesing azo compounds, the
highest bathochromic effect was reported for the 2-azo thi-
azoles because “both more excited-state stabilization and
less ground-state stabilization participate in the
bathochromism of 2-thiazolylazo (as well as of thienylazo)
dyes" [23]. As the presence of 1-azulenyl moiety in azo
derivatives produces a bathochromic shift in main visible
band [24] as well, a dramatic bathochromic effect for the
azulene-1-azo-2'-thiazols is expected. Indeed, Table 1
shows a strong shift for azo thiazole, which surpasses with
35 nm and 20 nm the values for the corresponding phenyl-
and 4-pyridyl-substituted compounds.
Scheme 7
Table 1
Conclusions.
λ
of the Main Visible Band for Azulene-1-azo
Aromatics in Cyclohexane
max
The synthesis and the physico-chemical properties of
compounds belonging to a new class of azo derivatives is
reported. The obtained azulene-1-azo-2'-thiazoles can be
attacked either to the position 3 in azulene or to thiazolic
nitrogen depending on the nature of the electrophile. Due
to the strong pull-push effect induced by both the azulene
moiety and the substituted thiazole, the reported com-
pounds exhibit a very strong bathochromic displacement
in UV-Vis and their extended electron conjugated system
brings about a solvatochromic effect. These optical proper-
ties could be useful in technical aims and in our opinion
some from the obtained compounds provided access to
materials exhibiting potential valuable optical utilities.
The investigations in this respect are in progress.
3
-1
-1
Compound
∆λ (nm)/logε (dm mol cm )
max
Azulene-1-azobenzene
Azulene-1-azo-4’-pyridine
Azulene-1-azo-2’-thiazole
415/4.30
429/4.39
450/4.42
The bathochromic effect is even larger when the thiazole
moiety is substituted at C-5 by an electron withdrawing
substituent [23], the most effective being the nitro group.
Indeed, as it can be seen from Table 2, the bathochromic
shift induced by this group reaches 78 nm. Unfortunately,
because of its high light sensitivity, the use of the nitro
compound 5NO in technical purposes is questionable.
2
Table 2
The Difference Between the Values of the Main Visible Band for Unsubstituted and Substituted Azulene-1-azo-2’-thiazoles (∆λ ) in Methanol
max
+
-
+
Substituent
Compound
5-Cl
5Cl
5-Br
5Br
5-NCS
5NCS
5-CO CH
N -O
N -CH
5-NO
2
2
3
3
5CO CH
25
28
5NO
2
3
2
∆λ
3
19
29
33
46
68
78
max

Nov-Dec 2003
Azulene-1-azo-2'-thiazoles. Synthesis and Properties
999
Table 3
3
-1
-1
The Solvent Effect on λ (nm)/lg ε(dm mol cm ) for the Main Visible Band of Azulene-1-azo-2’-thiazoles
max
Comp.
5H
5Cl
5Br
Solvent
C H
450(4.42)
465(4.41)
475(4.44)
477(4.39)
472(4.38)
510(4.44)
-
C H CH
(CH ) CO CH CN
CH OH
DMF [a]
481(4.41)
494(4.41)
498(4.43)
506(4.31)
508(4.39)
571(4.47)
561(4.26)
524(4.40)
H O
6
12
6
5
3
3 2
3
3
2
466(4.44)
484(4.42)
486(4.45)
494(4.41)
492(4.37)
536(4.45)
465(4.42)
468(4.40)
475(4.44)
488(4.44)
494(4.47)
504(4.39)
508(4.34)
553(4.50)
561(4.31)
521(4.44)
490(4.44)
490(4.44)
495(4.45)
510(4.39)
514(4.34)
573(4.45)
558(4.26)
530(4.40)
484(4.48)
486(4.45)
494(4.39)
496(4.39)
546(4.52)
481(4.48)
488(4.50)
498(4.30)
496(4.36)
556(4.45)
561(4.30)
514(4.28)
5SCN
5CO CH
2
3
5NO
28
2
25
576(4.26) [b] 561(4.25)
521(4.32) 515(4.40)
510(4.40)
[a] DMF: dimethylformamide; [b] not dried.
mg, 1.1 mmol) and the mixture was stirred until complete disso-
The presented diazotization of 2-amino-3-oxy-4-
phenylthiazole represent the first example of diazonium
salts generation starting from a five-atom nitrogenous
heterocyclic amine containing N-O bond. Although the
N-oxides are relatively strong oxidants while azulene deriv-
atives are well known for their sensitivity toward oxidants,
the obtained azo derivatives, as well as the corresponding
pyridine N-oxide derivatives, are stable compounds.
lution. Then, NaNO (crystals), (77 mg, 1.1 mmol) was slowly
2
added, at 0 °C. A very small amount of ice was added to this solu-
tion and the mixture was poured at 0 °C in a well-stirred solution
of azulene (128 mg, 1 mmol), and potassium acetate (4 g), in
methanol, (30 mL). In a short time the color turned red. After 15
min of stirring at 0 °C, aqueous sodium carbonate (20 %) was
added for neutralization and the solution was let to reach room
temperature. The mixture was extracted with DCM (3 × 25 mL)
and the combined organic layers were washed with water, dried
Acknowledgements.
(Na SO ) and the solvent was evaporated in vacuum. The residue
2
4
was separated by column chromatography mainly on silica gel,
using n-pentane for unreacted azulenes and a mixture of DCM-
ethyl acetate as eluents for azo compounds. The conversion and
the yields are presented in Schemes 1 and 4. Further particular
The authors thank to Prof. Klaus Hafner as well as to
Institute of Organic Chemistry from T. U. Darmstadt for
providing us some of the starting azulenes. The authors
thank to Instrumental Analysis Department of Institute of
Organic Chemistry-Bucharest.
details for the synthesis of azo compounds 5SO H, 5p-
3
CH C H N , 22 and 25-27 are described below.
3
6 4 2
2-(Azulen-1-yldiazenyl)-1,3-thiazole, (5H).
EXPERIMENTAL
This compound was obtained as dark brown crystals, mp 80
°C; ir: 740, 780, 790, 845, 885, 1015, 1130, 1200, 1230, 1260,
1300, 1330, 1350, 1380, 1420, 1450, 1480, 1570, 1615, 2370,
Melting points: Kofler apparatus (Reichert Austria). Elemental
analyses: Perkin Elmer CHN 240B. UV spectra: Beckman DK-
2A, UV 5240. IR spectra in potassium bromide: Beckman IR 5
–1
3080 cm ; uv (methanol): λ max (lg ε) 250 (4.24), 291 (4.18),
1
3
342 (3.73), 472 (4.36); H nmr (300 MHz, CDCl ): δ 7.26 (d, J
3
1
13
3
3
A. H- and C nmr spectra in CDCl : Bruker WM 300, AC 300,
= 3.3 Hz, 1 H, 5'-H), 7.40 (t, J = 9.7 Hz, 1 H, 5-H), 7.41 (d, J =
3
1
13
3
3
ARX 300 and Gemini 300 ( H: 300 MHz, C: 75 MHz), TMS
was used as internal standard; when necessary, unequivocal sig-
4.7 Hz, 1 H, 3-H), 7.52 (t, J = 9,7 Hz, 1 H, 7-H), 7.78 (t, J = 9.7
3
3
Hz, 1 H, 6-H), 7.92 (d, J = 3.3 Hz, 1 H, 4'-H), 8.31 (d, J = 9.8
1
1
1
13
3
3
nal assignment was confirmed by H- H COSY and H-
C
Hz, 1 H, 4-H), 8.36 (d, J = 4.5 Hz, 1 H, 2-H), 9.19 (d, J = 9.8
13
HETCOR experiments (the numbering for the compounds is
indicated in Schemes). Mass spectra: Finnigan MAT 311-A/100
MS. Column chromatography: silica gel [70-230 mesh (ASTM)]
or basic alumina (activity BII-III (Brockmann)). All eluted solu-
tions were filtered before solvent vaporization. Chloroform was
filtered on basic alumina. The dichloromethane (DCM) was dis-
tilled over calcium hydride and ethyl acetate over anhydrous
sodium carbonate. The reagents were commercial grade. The
commercially unavailable 2-aminothiazoles, 2Cl [25a],
Hz, 1 H, 8-H); C nmr (75 MHz, CDCl ): δ 118.7 (C-5'), 121.9
3
(C-3), 126.4 (C-2), 128.6 (C-5), 128.7 (C-7), 135.8 (C-8), 138.9
(C-4), 140.2 (C-6), 140.6 (C-8a), 143.1 (C-4'), 143.6 (C-3a),
+
145.7 (C-1), 179.7 (C-2'). ms: m/z 239 ([M] , 33.3), 212 (30.3),
167 (13), 166 (19), 154 (15), 128 (77), 101 (100).
Anal. Calcd. for C H N S: C, 65.26; H, 3.79; N, 17.57; S,
13
9 3
13.37. Found: C, 65.17; H, 3.78; N, 17.61; S, 13.44.
2-(Azulen-1-yldiazenyl)-5-chloro-1,3-thiazole, (5Cl).
2CO CH [25b], 2SCN [25c], 2SO H [25d] and 2pCH C H N
This compound was obtained as dark brown crystals, mp 191
°C; ir: 740, 785, 885, 1015, 1035, 1130, 1200, 1230, 1270, 1315,
1400, 1420, 1450, 1480, 1570, 1690, 2375 cm ; uv (methanol):
2
3
3
3 5 4 2
[25e], were prepared according to the literature. The nomencla-
ture was obtained using the ACD/I-Lab Web service
(ACD/IUPAC Name Free 7.06).
-1
λ max (lg ε) 229 (4.26), 295 (4.18), 347 (3.74), 488 (4.37), 698
1
3
(2.80); H nmr (300 MHz, CDCl ): δ 7.46 (d, J = 4.7 Hz, 1 H,
3
General Procedure for Azo Coupling.
3
3
3-H), 7.48 (t, J = 9.7 Hz, 1 H, 5-H), 7.60 (t, J = 9.7 Hz, 1 H,
7-H), 8.36 (d, J = 9.8 Hz, 1 H, 4-H), 7.85 (t, J = 9.7 Hz, 1 H,
6-H), 8.35 (d, J = 4.5 Hz, 1 H, 2-H), 7.72 (s, 1 H, 4'-H), 9.19 (d,
3
3
In a flask cooled at 0 °C, phosphoric acid (0.6 ml, 85 %) and
nitric acid (0.4 mL, 62 %) were added to 2-aminothiazole (110
3

1000
A. C. Razus, L. Birzan, S. Nae, M. N. Surugiu and V. Cimpeanu
Vol. 40
3
13
+
1 H, J = 9.8 Hz, 8-H); C nmr (75 MHz, CDCl ): δ 122.4 (C-3),
284 ([M] , 8), 255 (22), 210 (33), 166 (4), 155 (10), 153 (11), 140
(42), 127 (100), 113 (38).
3
126.7 (C-2), 127.1 (C-5'), 129.1 (C-5), 129.2 (C-7), 135.8 (C-8),
139.1 (C-4), 140.4 (C-6, C-8a), 141.0 (C-4'), 143.6 (C-3a), 146.2
(C-1), 177.2 (C-2'); ms: m/z 275 ([M] , 15), 273 ([M] , 48), 246
(51), 244 (63), 210 (23), 166 (21), 155 (20), 153 (31), 140 (61),
127 (100).
Anal. Calcd. for C H N SO : C, 54.92; H, 2.84; N, 19.72; S,
11.26. Found: C, 54.86; H, 2.75; N, 19.81; S, 11.34.
13
8
4
2
+
+
[2-(Azulen-1-yldiazenyl)-1,3-thiazole]-5-yl thiocyanate,
(5SCN).
Anal. Calcd. for C H ClN S: C, 56.93; H, 3.31; Cl, 12.76; N,
13
8
3
This compound was obtained as dark brown crystals, mp 182
°C; ir 755, 785, 845, 890, 1015, 1130, 1215, 1235, 1270, 1315,
15.33; S, 11.67. Found: C, 57.10; H, 2.85; Cl, 13.00; N, 15.41; S,
11.64.
-1
1400, 1450, 1570, 2170, 2380, 3030, 3080. cm ; uv (methanol):
2-(Azulen-1-yldiazenyl)-5-bromo-1,3-thiazole, (5Br).
1
λ max (lg ε) 250 (4.31), 291 (4.18), 348 (3.72), 496 (4.47); H
3
3
This compound was obtained as dark brown crystals, mp 207
°C; ir: 740, 770, 790, 850, 1000, 1015, 1035, 1130, 1200, 1230,
nmr (CDCl ): δ 7.48 (d, J = 4.7 Hz, 1 H, 3-H), 7.57 (t, J = 9.7
3
3
3
Hz, 1 H, 5-H), 7.69 (t, J = 9,7 Hz, 1 H, 7-H), 7.91 (t, J = 9.7 Hz,
1 H, 6-H), 8.06 (s, 1 H, 4'-H), 8.33 (d, J = 4.5 Hz, 1 H, 2-H), 8.39
(d, J = 9.8 Hz, 1 H, 4-H), 9.20 (d, 1 H, J = 9.8 Hz, 8-H);
-1
3
1270, 1310, 1380, 1420, 1450, 1480, 1570, 1700, 2375 cm ; uv
3
3
13
(methanol): λ
(lg ε) 228 (4.20), 293 (4.19), 346 (3.88), 486
C
max
1
3
(4.35), 694 (2.80). H nmr (300 MHz, CDCl ): δ 7.44 (d, J = 4.7
Hz, 1 H, 3-H), 7.47 (t, J = 9.7 Hz, 1 H, 5-H), 7.58 (t, J = 9,7 Hz,
1 H, 7-H), 8.35 (d, J = 9.8 Hz, 1 H, 4-H), 7.83 (t, J = 9.7 Hz,
nmr (75 MHz, CDCl ): δ 113.4 (CN), 144.2 (C-5'), 123.5 (C-3),
3
3
3
3
126.4 (C-2), 130.4 (C-5), 130.6 (C-7), 136.2 (C-8), 139.6 (C-4),
141.0 (C-6), 141.0 (C-8a), 143.2 (C-3a), 147.4 (C-1), 150.7
3
3
3
+
1 H, 6-H), 8.33 (d, J = 4.5 Hz, 1 H, 2-H), 7.82 (s, 1 H, 4'-H), 9.16
(C-4'), 184.6 (C-2'); ms: m/z 296 ([M] , 4), 267 (14), 210 (20),
3
13
(d, 1 H, J = 9.8 Hz, 8-H); C nmr (75 MHz, CDCl ): δ 122.5
166 (5), 155 (4), 153 (5), 140 (22), 127 (100), 113 (23).
3
(C-3), 126.8 (C-2), 110.2 (C-5'), 129.2 (C-5), 129.3 (C-7), 135.9
(C-8), 139.2 (C-4), 140.5 (C-6, C-8a), 144.2 (C-4'), 143.6 (C-3a),
146.3 (C-1), 175.2 (C-2'); ms: m/z 319 ([M] , 9), 317 ([M] , 9),
290 (21), 288 (24), 210 (25), 166 (22), 155 (22), 153 (33), 140
(72), 126 (100).
Anal. Calcd. for C H N S : C, 56.75; H, 2.72; N, 18.92; S,
21.60. Found: C, 56.69; H, 2.68: N, 18.85: S, 21.78.
14
8 4 2
+
+
Bis[2-(azulen-1-yldiazenyl)-1,3-thiazole-5-thio], (6).
Compound 6 is obtained as by product together with com-
pound 5SCN and is not available in sufficient amount for com-
plete characterization, uv (methanol): λ max (lg ε) 226 (4.60),
Anal. Calcd. for C H BrN S: C, 49.06; H, 2.85; Br, 24.82; N,
13
8
3
13.21; S, 10.06. Found: C, 49.00; H, 2.55; N, 13.15; S, 10.20; Br,
25.10.
1
288 (4.49), 333 (4.02), 492 (4.68); H nmr (300 MHz, CDCl ): δ
3
3
3
7.48 (d, J = 4.7 Hz, 2 H, 3-H), 7.53 (t, J = 9.7 Hz, 2 H, 5-H),
7.56 (t, J = 9,7 Hz, 2 H, 7-H), 7.83 (t, J = 9.7 Hz, 2 H, 6-H),
7.96 (s, 2 H, 4'-H), 8.36 (d, J = 4.5 Hz, 2 H, 2-H), 8.37 (d, J =
9.8 Hz, 2 H, 4-H), 9.22 (d, J = 9.8 Hz, 2 H, 8-H).
Methyl 2-(azulen-1-yldiazenyl)-1,3-thiazole-5-carboxylate,
3
3
(5CO CH ).
2
3
3
3
3
This compound was obtained as dark brown crystals, mp 188
°C; ir 740, 775, 805, 860, 1015, 1090, 1140, 1205, 1230, 1245,
Anal. Calcd. for C
H N S : C, 57.78; H, 2.96; N, 15.56: S,
26 16 6 4
-1
1298, 1310, 1400, 1430, 1460, 1480, 1700, 1690, 2375 cm ; uv
23.70. Found: C, 57.70; H, 3.04; N, 15.64; S, 23.62.
(methanol): λ max (lg ε) 226 (4.29), 285 (4.18), 349 (3.74), 500
2-[(4,8-Dimethylazulen-1-yl)diazenyl]-4-phenyl-1,3-thiazole,
(18).
1
(4.20). H nmr (300 MHz, acetone-d ): δ 3.88 (s, 3 H, Me), 7.72
6
3
3
(d, J = 4.7 Hz, 1 H, 3-H), 7.84 (t, J = 9.7 Hz, 1 H, 5-H), 7.95 (t,
J = 9,7 Hz, 1 H, 7-H), 8.19 (t, J = 9.7 Hz, 1 H, 6-H), 8.26 (d,
J = 4.5 Hz, 1 H, 2-H), 8.50 (s, 1 H, 4'-H), 8.74 (d, J = 9.8 Hz,
1 H, 4-H), 9.26 (d, 1 H, J = 9.8 Hz, 8-H); C nmr (75 MHz, ace-
3
3
3
This compound was obtained as dark-red crystals mp 205 °C;
ir 690, 740, 775, 785, 805, 860, 905, 1000, 1020, 1075, 1180,
1210, 1240, 1285, 1300, 1360, 1440, 1455, 1480, 1570, 2380
3
3
13
-1
cm ; uv (methanol): λ max (lg ε) 231 (4.41), 250 (4.38), 309
tone-d ): δ 124.3 (C-3), 125.8 (C-2), 125.7 (C-5'), 132.0 (C-5),
6
1
(4.12), 333sh (3.76), 492 (4.45); H nmr (300 MHz, CDCl ): δ
132.1 (C-7), 136.2 (C-8), 142.5 (C-8a), 140.9 (C-4), 142.5 (C-6),
148.6 (C-4'), 142.4 (C-3a), 147.3 (C-1), 161.5 (OMe), 182.7 (C-
3
3
2.85 (s, 3 H, 4-Me), 3.24 (s, 3 H, 8-Me), 7.30 (d, J = 10.1 Hz,
1 H, 5-H), 7.36 (s, 1 H, 5'-H), 7.37 (tt, J = 8.6 Hz, J = 1.0 Hz,
3
4
+
2'); ms m/z: 298 (13), 297 ([M] , 53), 270 (22), 269 (64), 268
3
3
1 H, 4"-H), 7.38 (d, J = 10.1 Hz, 1 H, 7-H), 7.40 (d, J = 4.9 Hz,
(71), 210 (20), 166 (15), 155 (20), 153 (21), 140 (80), 126 (100).
3
4
1 H, 3-H), 7.44 (tt, J = 8.6 Hz, J = 1.0 Hz, 2 H, 3"-H, 5"-H),
Anal. Calcd. for C H N SO : C, 62.12; H, 3.59; N, 13.59; S,
16 11
3
2
3
3
4
7.48 (t, J = 10.2 Hz, 1 H, 6-H), 8.02 (dt, J = 8.6 Hz, J = 1.0
Hz, 2 H, 2"-H, 6"-H), 8.35 (d, J = 5.1 Hz, 2-H); C nmr (75
10.35. Found: C, 62.10; H, 3.50; N, 13.61; S, 10.34.
3
13
2-(Azulen-1-yldiazenyl)-5-nitro-1,3-thiazole, (5NO ).
2
MHz, CDCl ): δ 24.55 (Me-4), 29.36 (Me-8), 112.1 (C-5'), 120.2
3
This compound was obtained as dark brown crystals, mp 260
°C; ir 740, 770, 810, 845, 1010, 1115, 1140, 1200, 1230, 1280,
1320, 1340, 1480, 1560, 1615, 1705, 2375, 2860, 2915 cm ; uv
(C-3), 128.0 (C-2), 124.8 (C-3", C-5"), 126.1 (C-2", C-6"), 128.6
(C-4"), 134.5 (C-1"), 131.8 (C-5), 133.7 (C-7), 149.1 (C-8),
151.8 (C-4), 137.0 (C-6), 137.1 (C-8a), 154.9 (C-4'), 146.9
(C-3a), 144.7 (C-1), 179.7 (C-2'); ms: m/z 343 ([M] , 23), 315
(28), 314 (27), 300 (29), 168 (100), 153 (100), 128 (58), 77 (67).
-1
+
(methanol): λ max (lg ε) 226 (4.25), 291 (4.17), 335 (3.88), 546
1
3
(4.20), 698 (2.80); H nmr (300 MHz, CDCl ): δ 7.55 (d, J = 4.7
3
3
3
Hz, 1 H, 3-H), 7.70 (t, J = 9.7 Hz, 1 H, 5-H), 7.83 (t, J = 9,7 Hz,
Anal. Calcd. for C
H N S: C, 73.44; H, 4.99; N, 12.23; S,
21 17 3
3
3
1 H, 7-H), 8.02 (t, J = 9.7 Hz, 1 H, 6-H), 8.38 (d, J = 4.5 Hz, 1
9.33. Found: C, 73.25; H, 4.95; N, 12.21, S, 9.59.
3
H, 2-H), 8.47 (d, J = 9.8 Hz, 1 H, 4-H), 8.65 (s, 1 H, 4'-H), 9.30
(d, 1 H, J = 9.8 Hz, 8-H); C nmr (75 MHz, DMSO-d ): δ =
2-[(3-tert-Butylazulen-1-yl)diazenyl]-4-phenyl-1,3-thiazole, (19).
3
13
6
This compound was obtained as red crystals, mp 197 °C; ir
670, 690, 730, 740, 755, 865, 885, 905, 1020, 1035, 1080, 1175,
1190, 1210, 1285, 1305, 1335, 1420, 1455, 1570, 2380, 2850,
126.0 (C-2), 126.5 (C-3), 127.3 (C-5'), 134.3 (C-7), 134.4 (C-5),
137.1 (C-8), 140.6 (C-8a), 141.6 (C-4), 143.3 (C-3a), 143.5
(C-6), 145.3 (C-4'), 149.3 (C-1), 182.2 (C-2'); ms: m/z 285 (1),

Nov-Dec 2003
Azulene-1-azo-2'-thiazoles. Synthesis and Properties
1001
-1
2-(Azulen-1-yldiazenyl)-1,3-thiazole-5-sulfonic acid, (5SO H).
2915, 2950 cm ; uv (methanol) λ
(lg ε): 231 (4.37), 250
3
max
1
(4.36), 298 (4.21), 333 (3.87), 500 (4.45); H nmr (300 MHz,
CDCl ): δ 1.59 (s, 3 H, Me), 7.39 (t, J = 10.1 Hz, 1 H, 5-H), 7.45
(s, 1 H, 5'-H), 7.39 (tt, J = 8.6 Hz, J = 1.0 Hz, 1 H, 4"-H), 7.49
(t, J = 10.1 Hz, 1 H, 7-H), 7.45 (tt, J = 8.6 Hz, J = 1.0 Hz, 2 H,
3"-H 5"-H), 7.77 (t, J = 9.8 Hz, 1 H, 6-H), 8.06 (dt, J = 8.6 Hz,
J = 1.0 Hz, 2 H, 2"-H, 6"-H), 8.39 (d, J = 5.1 Hz, 2-H), 8.70 (d,
J = 9.8 Hz, 1 H, 4-H), 9.23 (d, J = 9.8 Hz, 1 H, 8-H); C nmr
Due to the high solubility of the resulting zwitterion in water,
the methanolic solution was evaporated and the solid was contin-
uously extracted with DCM in an extractor. After solvent
removal, the obtained red solid was separated by column chro-
matography on silica gel using n-pentane for the unreacted azu-
3
3
3
4
3
3
4
3
3
4
3
3
lene and ethyl acetate:methanol, 4:1, for azo compound 5SO H.
3
3
13
This compound was obtained as dark red-brown crystals, mp 235
°C; ir 670, 745, 780, 790, 825, 835, 860, 1015, 1110, 1135, 1200,
(75 MHz, CDCl ): δ 112.5 (C-5'), 124.6 (C-3", C-5"), 126.3 (C-
3
2", C-6"), 127.4 (C-3), 127.8 (C-2), 128.5 (C-4"), 128.6 (C-5),
128.7 (C-7), 134.6 (C-1"), 135.5 (C-4), 138.0 (C-8), 140.3 (C-6),
142.3 (C-8a), 143.1 (C-3a), 144.5 (C-1), 155.3 (C-4'), 179.5
(C-2'); ms: m/z 371 ([M] , 24), 328 (36), 286 (64), 174 (36), 165
(39), 152 (100), 134 (54), 77 (52).
-1
1260, 1385, 1450, 1620, 2350, 2900-3600 cm ; uv (methanol), λ
max (lg ε) 229 (4.30), 293 (4.19), 344 (3.72), 488 (4.37), 698
1
+
(2.80); H nmr (300 MHz, DMSO-d ): δ 4.66 (s, 1 H, N H), 7.66
6
+
3
3
(d, J = 4.8 Hz, 1 H, 3-H), 7.73 (t, J = 9.6 Hz, 1 H, 5-H), 7.84 (t,
J = 9.6 Hz, 1 H, 7-H), 7.88 (s, 1 H, 4'-H), 8.10 (t, J = 9.6 Hz,
1 H, 6-H), 8.19 (d, J = 4.5 Hz, 1 H, 2-H), 8.67 (d, J = 9.8 Hz,
1 H, 4-H), 9.16 (d, J = 9.6 Hz, 1 H, 8-H); C nmr (75 MHz,
3
3
Anal. Calcd. for C
8.63. Found: C, 74.35; H, 5.65; N, 11.41; S, 8.59.
H N S: C, 74.36; H, 5.70; N, 11.31; S,
3
3
23 21 3
3
13
DMSO-d ): δ 123.4 (C-3), 125.4 (C-2), 131.0 (C-5, C-7), 135.9
2-[(4,6,8-Trimethylazulen-1-yl)diazenyl]-4-phenyl-1,3-thiazole,
6
(C-8), 140.4 (C-4'), 140.7 (C-4), 141.1 (C-8a), 142.2 (C-6), 143.0
(C-3a), 143.9 (C-5'), 146.3 (C-1), 178.2 (C-2').
(20).
This compound was obtained as dark-red crystals mp 214 °C;
ir 680, 740, 780, 800, 820, 845, 900, 1020, 1080, 1200, 1230,
1290, 1300, 1310, 1350, 1440, 1450, 1480, 1570, 2370 cm ; uv
(methanol): λ max (lg ε) 234 (4.40), 246sh (4.33), 255sh (4.33),
313 (4.15), 326sh (3.92), 498 (4.37); H nmr (300 MHz, CDCl ):
δ 2.67 (s, 3 H, 6-Me), 2.87 (s, 3 H, 4-Me), 3.30 (s, 3 H, 8-Me),
7.33 (d, J = 1.2 Hz, 1 H, 5-H), 7.35 (tt, J = 8.6 Hz, J = 1.0 Hz,
1 H, 4"-H), 7.39 (s, 1 H, 5'-H), 7.40 (d, J = 4.9 Hz, 1 H, 3-H),
7.44 (bs, 1 H, 7-H), 7.45 (tt, J = 8.6 Hz, J = 1.0 Hz, 2 H, 3"-H,
Anal. Calcd. for C H N O S : C, 48.89; H, 2.84; N, 13.16; S,
13
9 3 3 2
20.08. Found: C, 48.86; H, 2.78; N, 13.25; S, 20.56.
-1
Generation of Double-coupled Thiazols, 22 and 5pCH C H N .
3
6 4 2
1
3
For the generation of 22 and 5pCH C H N the corresponding
3
6 4 2
aminothiazols 11 and 2H were first coupled with a diazonium salt
obtained from p-methylaniline and then the reaction mixture was
in situ diazotized at thiazole amino group and coupled with azu-
lene. Starting from 11 the intermediate 12 was separated and char-
acterized. This compound (1 g, 3.42 mmole, 10 % excess) was dia-
zotized and coupled with azulene. After work-up, four fractions
were obtained by chromatographic separation: fraction 1 (blue),
unreacted azulene (cca 6 %), fraction 2 (yellow-green), 1-azulen-1-
yl-2-(4-methylphenyl)diazene, 9, (62 mg, 8 %), fraction 3 (brown),
mono coupled compound 17, (150 mg, 15 %), fraction 4 (violet-
blue), double coupled compound 22, (76 mg, 5 %). Starting from
4
3
4
3
3
4
3
4
5"-H), 8.06 (dt, J = 8.6 Hz, J = 1.0 Hz, 2 H, 2"-H, 6"-H), 8.31
3
13
(d, J = 5.1 Hz, 2-H). C nmr (75 MHz, CDCl ): δ 24.44 (Me-4),
3
28.59 (Me-6), 29.71 (Me-8), 111.9 (C-5'), 120.3 (C-3), 127.9
(C-2), 123.7 (C-3", C-5"), 126.3 (C-2", C-6"), 128.4 (C-4"),
134.6 (C-1"), 133.3 (C-5), 135.7 (C-7), 148.0 (C-8), 150.6 (C-4),
148.9 (C-6), 135.5 (C-8a), 155.0 (C-4'), 147.2 (C-3a), 143.4 (C-
1), 179.9 (C-2'); ms: m/z 357 ([M] , 16), 342 (11), 329 (11), 314
(17), 182 (100), 176 (84), 153 (40), 134 (37), 84 (36).
+
2H, the intermediate 5 pCH C H N was not separated and from
3
6 4 2
Anal. Calcd. for C
8.68. Found: C, 74.75; H, 5.15; N, 11.21; S, 8.89.
H N S: C, 74.77; H, 5.18; N, 11.37; S,
22 19 3
the reaction mixture only 5pCH C H N was separated (in yield
3 6 4 2
under 5 %) and traces of the compound 9 were observed.
2[(5-Isopropyl-3,8-dimethylazulen-1-yl)diazenyl]-4-phenyl-1,3-
thiazole, (21).
5[(4-Methylphenyl)diazenyl]-4-phenyl-1,3-thiazol-2-amine, (12).
This compound was obtained as dark yellow crystals, mp 203
1
This compound was obtained as red crystals, mp 87 °C; ir 685,
735, 775, 810, 860, 900, 960, 1000, 1030, 1100, 1165, 1230,
°C (lit [23] 200 °C); H nmr (300 MHz, CDCl ): δ 2.34 (s, 3 H,
3
3
3
CH ), 7.29 (d, J = 10.0 Hz, 2 H, 2'-H, 6'-H), 7.37 (tt, J = 6.7
Hz, J = 1.5 Hz, 1 H, 4"-H), 7.51 (t, J = 7.8 Hz, 2 H, 3"-H, 5"-
H), 7.55 (t, J = 8.2 Hz, 2 H, 3'-H, 5'-H), 8.21 (dd, J = 8.3 Hz, J
= 1.4 Hz, 2 H, 2'-H, 6'-H), 8.34 (s, 2 H, NH ); C nmr (75 MHz,
3
-1
4
3
1290, 1300, 1330, 1440, 1455, 1560, 2380, 2970 cm ; uv
3
3
4
(methanol): λ max (lg ε) 235 (4.39), 259 (4.42), 300 (4.14), 323
1
3
13
(3.86), 517 (4.38); H nmr (300 MHz, CDCl ): δ 1.36 (d, J = 6.9
3
2
3
Hz, 6 H, CHMe), 2.54 (s, 3 H, 3-Me), 3.09 (hept, J = 6.9 Hz,
1 H, CHMe), 3.20 (s, 3 H, 8-Me), 7.35 (tt, J = 8.6 Hz, J = 1.0
Hz, 1 H, 4"-H), 7.32 (s, 1 H, 5'-H), 7.40 (bd, J = 9.7 Hz, 1 H,
7-H), 7.42 (tt, J = 8.6 Hz, J = 1.0 Hz, 2 H, 3"-H, C5"-H), 7.50
(dt, J = 9.7 Hz, J = 2.0 Hz, 1 H, 6-H), 8.02 (dt, J = 8.6 Hz, J =
1.0 Hz, 2 H, 2"-H, 6"-H), 8.12 (d, J = 1.9 Hz, 4-H), 8.21 (s, 1 H,
2-H); C nmr (75 MHz, CDCl ): δ 13.14 (Me3 ), 24.25 (CHMe),
CDCl ): δ 20.89 (Me), 121.8 (C-2', C-6'), 128.5 (C-3', C-5'),
3
3
4
129.5 (C3', C5'), 129.8 (C2", C6"), 129.9 (C4"), 133.8 (C1"),
138.9 (C-4'), 139.9 (C-5), 150.5 (C-1), 154.6 (C-4), 169.3 (C-2);
3
3
4
+
ms: m/z: 294 ([M] , 63), 293 (100), 133 (17), 91 (65).
3
4
3
4
2-(Azulen-1-yldiazenyl)-4-phenyl-1,3-thiazole, (17).
4
13
This compound was obtained as red crystals, mp 163 °C; ir
670, 690, 725, 750, 775, 780, 820, 865, 870, 905, 1020, 1035,
1080, 1175, 1190, 1210, 1275, 1305, 1320, 1365, 1410, 1445,
3
28.58(Me8), 38.16(CHMe), 111.6 (C-5'), 126.7 (C-2), 126.3
(C-3", C-5"), 128.2 (C-3),128.5 (C-2", C-6"), 128.9 (C-4"), 131.2
(C-7), 134.6 (C-1"), 135.2 (C-4), 136.7 (C-6), 138.0 (C-8a),
145.5 (C-3a), 144.9 (C-1), 149.3 (C-8), 149.6 (C-5), 154.8 (C-4'),
-1
1560, 1580, 2380 cm ; uv (methanol): λ max (lg ε) 226 (4.40),
1
238sh (4.33), 247sh (4.33), 296 (4.24), 336 (3.87), 486 (4.45); H
3
+
+
nmr (300 MHz, CDCl ): δ 7.36 (s, 1 H, 5'-H), 7.48 (t, J = 9.7 Hz,
180.0 (C-2'). MS (m/z): 386 ([M] +1, 1), 384 ([M] -1, 1), 358
(1), 356 (1), 211 (7), 176 (100), 134 (98).
3
3
3
1 H, 5-H), 7.47 (t, J = 7.0 Hz, 2 H, 3"-H, 5"-H), 7.47 (d, J = 4.7
Hz, 1 H, 3-H), 7.47 (t, J = 7.0 Hz, 1 H, 4"-H), 7.60 (t, J = 10.0
Hz, 1 H, 7-H), 7.84 (t, J = 10.0 Hz, 1 H, 6-H), 8.05 (d, J = 8.0
3
3
Anal. Calcd. for C
H N S: C, 74.77; H, 6.01; N, 10.90; S,
24 23 3
3
3
8.32. Found: C, 74.79; H, 6.09; N, 10.81; S, 8.31.

1002
A. C. Razus, L. Birzan, S. Nae, M. N. Surugiu and V. Cimpeanu
Vol. 40
3
3
3
13
Hz, 2 H, 2"-H, 6"-H), 8.38 (d, J = 9.6 Hz, 1 H, 4-H), 8.46 (d, J
2-H), 9.12 (d, 1 H, J = 9.6 Hz, 8-H); C nmr (100 MHz,
3
13
= 4.6 Hz, 1H, 2-H), 9.27 (d, 1 H, J = 9.6 Hz, 8-H). C nmr (75
CDCl ): δ = 112.6 (C-5'), 123.1 (C-3), 127.7 (C-2), 128.3 (3"),
3
MHz, CDCl ): δ 112.7 (C-5'), 122.2 (C-3), 126.8 (C-2), 126.2 (C-
128.5 (2"), 129.3 (4"), 129.0 (C-1"), 129.3 (C-5), 129.6 (C-7),
136.1 (C-8), 139.0 (C-4), 140.5 (C-6, C-8a), 147.1 (C-4'), 145.6
(C-3a), 146.6 (C-1), 160.5 (C-2'). MS (m/z): 332 (M+1, 1), 288
(69), 286 (100), 284 (51), 260 (7), 205 (11), 205 (11), 143 (15),
126 (94).
3
3", C-5"), 126.5 (C-2", C-6"), 128.5 (C-4"), 134.5 (C-1"), 128.7
(C-5), 128.8 (C-7), 138.9 (C-8), 135.8 (C-4), 139.2 (C-6), 138.9
(C-8a), 158.3 (C-4'), 144.7 (C-3a), 145.9 (C-1), 177.0 (C-2'); ms:
+
m/z 315 ([M] , 3), 287 (20), 286 (73), 140 (10), 127 (100).
Anal. Calcd. for C
H N S: C, 72.36; H, 4.15; N, 13.32; S,
Anal. Calcd. for C
H N SO: C, 68.86; H, 3.95; N, 12.68; S,
19 13 3
19 13 3
10.17. Found: C, 72.56; H, 4.25; N, 13.21; S, 9.98.
9.67. Found: C, 68.67; H, 3.82, N, 12.71, S, 9.70.
2-(Azulen-1-yldiazenyl)-4-phenyl-5-[(4-methylphenyl)-
diazenyl]-1,3-thiazole, (22).
4-Phenyl-2-[(4,6,8-trimethylazulen-1-yl)diazenyl]-1,3-thiazole
3-Oxide, (26).
This compound is not available in sufficient amount for the
This compound was obtained as dark violet crystals, mp 250
1
complete characterization: H nmr (400 MHz, CDCl ): δ 2.45 (s, 3
°C; uv (methanol): λ max (lg ε) 235 (4.49), 254sh (4.38), 264sh
3
3
3
1
H, Me), 7.32 (d, J = 8.8 Hz, 2 H, 3'''-H, 5'''-H), 7.47 (t, J = 6.8 Hz,
(4.38), 309 (4.05), 543 (4.52); H nmr (400 MHz, CDCl ): δ 2.65
3
3
3
1 H, 4'''-H), 7.52 (d, J = 4.8 Hz, 1 H, 3-H), 7.54 (t, J = 6.8 Hz, 2
(s, 3 H, 6-Me), 2.84 (s, 3 H, 4-Me), 3.21 (s, 3 H, 8-Me), 7.21 (s, 1
3
3
3
H, 3"-H, 5"-H), 7.55 (t, J = 9.6 Hz, 1 H, 5-H), 7.69 (t, J =9.8 Hz,
1 H, 7-H), 7.81 (d, J = 8.0 Hz, 2 H, 2'''-H, 6'''-H), 7.90 (t, J = 10.0
Hz ,1 H, 6-H), 8.41 (d, J = 10.0 Hz, 1 H, 4-H), 8.46 (d, J = 5.2 Hz,
1 H, 2-H), 8.47 (d, J =7.2 Hz, 2 H, 2"-H, 6"-H), 9.34 (d, J = 10.0
H, 5'-H), 7.32 (bs, 1 H, 5-H), 7.38 (d, J = 5.2 Hz, 1 H, 3-H), 7.40
3
3
3
3
(bs, 1 H, 7-H), 7.48 (t, J = 7.2 Hz, 1 H, 4"-H), 7.46 (t, J = 7.2 Hz,
3
3
3
3
2 H, 3"-H, 5"-H), 8.36 (d, J = 4.8 Hz, 1 H, 2-H), 7.97 (d, J = 8.0
3
3
13
Hz, 2 H, 2"-H, 6"-H); C nmr (100 MHz, CDCl ): δ 25.45 (Me-
3
+
Hz, 1 H, 8-H); ms: m/z 434 (1), 433 ([M] , 4), 404 (4), 286 (5), 284
4), 28.57 (Me-6), 29.53 (Me-8), 111.4 (C-5'), 121.5 (C-3), 124.8
(C-2), 128.3 (C-3", C-5"), 128.4 (C-2", C-6"), 129.4 (C-4"), 129.2
(C-1"), 134.1 (C-5), 136.4 (C-7), 148.2 (C-8), 149.3 (C-6), 150.9
(C-4), 136.5 (C-8a), 150.9 (C-4'), 146.9 (C-3a), 144.4 (C-1), 149.4
(6), 153 (54), 127 (46), 126 (24), 89 (100), 77 (48).
Anal. Calcd. for C
H N S: C, 72.03; H, 4.42; N, 16.16; S,
26 19 5
7.38. Found: C, 72.06: H, 4.56; N, 16.10: S, 7.28.
+
(C-2'); ms: m/z 373 ([M] , 1), 357 (6), 342 (4), 329 (6), 314 (13),
2-(Azulen-1-yldiazenyl)-5-[(4-methylphenyl)diazenyl]-1,3-thia-
224 (20), 222 (22), 182 (82), 176 (100), 153 (50), 134 (85).
zole, (5pCH C H N ).
3
6 4 2
Anal. Calcd. for C
H N SO: C, 70.75; H, 5.13; N, 11.25; S,
22 19 3
This compound was obtained as black crystals, mp 105 °C; uv
(methanol): λ max (lg ε) 225 (4.22), 240sh (4.10), 294 (4.05),
8.58. Found: C, 70.67; H, 5.22; N, 11.21; S, 8.50.
1
2-[(5-Isopropyl-3,8-dimethylazulen-1-yl)diazenyl]-4-phenyl-
1,3-thiazole 3-Oxide, (27).
350 (3.99), 556 (4.24); H nmr (300 MHz, CDCl ): δ 2.45 (s, 3
3
3
3
H, Me), 7.32 (d, J = 8.0 Hz, 2 H, 3''-H, 5''-H); 7.51 (d, J = 4.7
Hz, 1 H, 3-H), 7.54 (t, J = 9.6 Hz, 1 H, 5-H); 7.67 (t, J =9,7 Hz,
3
3
This compound was obtained as blue crystals, mp 133 °C
3
3
1 H, 7-H), 7.81 (d, J = 8.4 Hz, 2 H, 2''-H, 6''-H); 7.90 (t, J = 9.7
(dec.); UV (methanol): λ max (lg ε) 234 (4.45), 246sh (4.43),
3
3
Hz, 1 H, 6-H), 8.40 (d, J = 9.8 Hz, 1 H, 4-H), 8.41 (d, J = 4.5
1
3
305 (4.12), 556 (4.28); H nmr (400 MHz, CDCl ): δ 1.38 (d, J
3
3
Hz, 1H, 2-H), 8.59 (s, 1H, 4'-H); 9.31 (d, 1 H, J = 9.9 Hz, 8-H);
ms: m/z 358 (1), 357 ([M] , 4), 328 (2), 300 (7), 218 (23), 210
3
= 6.9 Hz, 6 H, CHMe), 2.53 (s, 3 H, 3-Me), 3.12 (hept, J = 6.9
+
Hz, 1 H, CHMe), 3.19 (s, 3 H, 8-Me), 7.17 (s, 1 H, 5'-H), 7.44
(52), 179 (15), 166 (15), 155 (12), 153 (21), 141 (40), 140 (62),
127 (75), 126 (58), 119 (12), 113 (25), 91 (100).
3
(bd, J = 9.8 Hz, 1 H, 7-H), 7.45 (m, 3 H, H-3", H-4", H-5"), 7.54
3
3
(d, J = 9.8 Hz, 1 H, 6-H), 7.97 (d, J = 4.8 Hz, 2 H, 2"-H, 6"-H),
Anal. Calcd. for C
H N S: C, 67.21; H, 4.23; N, 19.61; S,
13
20 15 5
8.10 (s, 1 H, 2-H), 8.29 (s. 1 H, 4-H); C nmr (100 MHz,
8.95. Found: C, 67.26: H, 4.30; N, 19.50; S, 8.94.
CDCl ): δ 13.13 (Me3), 24.25 (CHMe), 28.38 (Me8), 38.35
3
(CHMe), 110.9 (C-5'), 126.7 (C-2), 127.8 (C-3", C-5"), 128.2
(C-3), 128.6 (C-2", C-6"), 129.4 (C-4"), 131.2 (C-7), 134.6
(C-1"), 135.2 (C-4), 136.7 (C-6), 138.0 (C-8a), 145.5 (C-3a),
144.9 (C-1), 149.3 (C-8), 149.6 (C-5), 150.0 (C-4'), 160.5 (C-2').
The Synthesis of Azo Compound, 25-27.
The diazotization of 4-phenyl-1,3-thiazol-2-amine 3-oxide
hydrochloride, 23.HCl, [17] and the coupling with azulenic com-
pounds, 4, 15 and 16, were carried out as usual. The solvent
removing occurred at room temperature and the chromatography
was performed on alumina using as eluent DCM:ethyl acetate
1:1. After the unreacted azulene, the second fraction (blue) con-
tained the azo compound, 25-27 (yields in Scheme 5).
+
MS (m/z): 402 ([M] , 1), 224 (1), 212 (1), 198 (63), 183 (100).
Anal. Calcd. for C
H N SO: C, 71.79; H, 5.77; N, 10.47; S,
24 23 3
7.98. Found: C, 71.68; H, 5.72; N, 10.51; S, 7.99.
Halogenations of the Compound 5H.
2-(Azulen-1-yldiazenyl)-4-phenyl-1,3-thiazole 3-Oxide, (25).
2-[(3-Bromoazulen-1-yl)diazenyl]-1,3-thiazole, (29Br).
This compound was obtained as dark red crystals, mp 141 °C;
ir 580, 650, 690, 705, 740, 755, 790, 850, 890, 950, 1010, 1030,
1050, 1150, 1160, 1245, 1250, 1280, 1375, 1435, 1490, 1560,
N-Bromosuccinimide (36 mg, 0.2 mmol) was added to the
solution of 5H, (48 mg, 0.2 mmol) in DCM (3 mL). The reaction
mixture was stirred for one hour, the solvent was evaporated to
dryness and the residue was separated by chromatography on alu-
mina using DCM as eluent. Three colored fractions were
obtained: fraction 1, unidentified products (8 mg), fraction 2,
bromo derivative 29Br, (40 mg, 76 %) and fraction 3 (8 mg unre-
acted 5H, 17 %). The compound 29Br was obtained as dark
brown crystals, mp 178 °C (dec); uv (methanol): λ max (lg ε) 212
-1
2380 cm ; uv (methanol): λ max (lg ε) 229 (4.41), 242sh (4.31),
1
254 (4.31), 297 (4.17), 364 (3.66), 530 (4.50); H nmr (400 MHz,
3
CDCl ): δ 7.32 (s, 1 H, 5'-H), 7.34 (t, J = 9.7 Hz, 1 H, 5-H), 7.47
3
3
3
(t, J = 7.0 Hz, 2 H, 3''-H, 5''-H), 7.46 (d, J = 4.7 Hz, 1 H, 3-H),
7.50 (t, J = 7.0 Hz, 1 H, 4"-H), 7.54 (t, J = 10.0 Hz, 1 H, 7-H),
7.79 (t, J = 10.0 Hz, 1 H, 6-H), 7.97 (d, J = 7.0 Hz, 1 H, 2''-H,
6''-H ), ( 8.30 (d, J = 9.6 Hz, 1 H, 4-H), 8.50 (d, J = 4.6 Hz, 1H,
3
3
3
3
1
3
3
(4.26), 230 (4.34), 294 (4.24), 345 (3.89), 479 (4.43). H nmr

Nov-Dec 2003
Azulene-1-azo-2'-thiazoles. Synthesis and Properties
1003
3
3
3
13
(300 MHz, CDCl ): δ 7.28 (d, J = 3.3 Hz, 1 H, 5'-H), 7.47 (t, J
J = 9.8 Hz, 1 H, 8-H); C nmr (75 MHz, CDCl ): δ 110.3 (CN),
3
3
3
3
= 9.8 Hz, 1 H, 5-H), 7.52 (t, J = 9,8 Hz, 1 H, 7-H), 7.82 (t, J =
9.8 Hz, 1 H, 6-H), 7.95 (d, J = 3.3 Hz, 2 H, 4'-H), 8.31 (s, 1 H,
2-H), 8.38 (d, J = 9.6 Hz, 1 H, 4-H), 9.10 (d, J = 9.8 Hz, 1 H,
8-H); C nmr (75 MHz, CDCl ): δ 111.3 (C-3), 119.1 (C-5'),
119.9 (C-5'), 141.2 (C-3), 131.9 (C-2), 130.1 (C-5), 131.0 (C-7),
137.5 (C-8), 137.9 (C-4), 142.3 (C-6), 139.3 (C-8a), 140.7
(C-3a), 143.7 (C-1), 143.7 (C-4'), 179.1 (C-2'); ms: m/z 296
3
3
3
13
+
([M] , 4), 267 (3), 239 (14), 210 (75), 184 (11), 140 (22), 127
3
127.3 (C-2), 128.6 (C-7), 129.0 (C-5), 136.0 (C-8), 138.4 (C-4),
141.8 (C-6), 139.5 (C-8a), 143.4 (C-4'), 141.0 (C-3a), 141.8
(C-1), 179.1 (C-2'); ms: m/z 319 (7), 317 ([M] , 7), 290 (8), 288
(100).
Anal. Calcd. for C H N S : C, 56.75; H, 2.72; N, 18.92; S,
21.60. Found: C, 56.65: H, 2.76; N, 18.90; S, 21.69.
14
8 4 2
+
(8), 210 (58), 207 (19), 205 (19), 140 (38), 126 (100).
Iodination of Compound 5H through Halomercuration.
Anal. Calcd. for C H BrN S: C, 49.06; H, 2.85; Br, 24.82; N,
13
8
3
The azo compound 5H (48 mg, 0.2 mmol) was dissolved in
acetonitrile (6 mL) and treated with mercury acetate (318 mg, 1
mmol). The reaction mixture was stirred for 3 hours at room tem-
perature, then cooled to 0 °C and treated with iodine (200 mg,
0.78 mmol). After 15 min at room temperature, to the mixture
DCM (10 mL) was added and washed with water (2 × 25 mL) for
13.21; S, 10.06. Found: C, 49.01; H, 2.90; Br, 24.83; N, 13.24; S,
10.02.
2-[(3-Chloroazulen-1-yl)diazenyl]-1,3-thiazole, (29Cl).
To the vigorous stirred solution of 5H (35 mg, 0.146 mmol) in
methanol (3 mL), solid potassium chlorate (8 mg, 0.066 mmol)
was added in one portion followed by drop addition of HCl solu-
tion (0.1 ml, 36 %) and the reaction mixture was stirred for
2 hours at room temperature. Then DCM (25 mL) was added and
the organic extract was neutralized with sodium bicarbonate
(20 %), washed with water, dried (Na SO ) and the solvent
mercury salts removing. The organic phase was dried (Na SO ),
2
4
the solvent was vaporised and the residue was separated on alu-
mina using n-pentane:DCM, 1:1. Three coloured fractions were
obtained: fraction 1, unidentified products (3 mg), fraction 2,
diiododerivative 8, (38 mg, 0.077 mmol, 39 %), fraction 3,
iodoproduct 7 (42 mg, 0.115 mmol, 56 %); starting material con-
version was quantitative.
2
4
vaporized to dryness. The residue was separated by chromatogra-
phy on silica gel using n-pentane:DCM (1:1 to 1:4) and three
colored fractions were obtained: fraction 1 (pink) unidentified
products (3 mg), fraction 2 (brown), chloro derivative 29Cl (19
mg, 79 %) and fraction 3 (brown) starting material, 5H (14 mg,
recovered 40 %). The compound 29Cl was obtained as dark
brown crystals, mp 192 °C; uv (methanol): λ max (lg ε) 212
2-[(3-Iodoazulen-1-yl)diazenyl]-1,3-thiazole, (7).
This compound was obtained as dark brown crystals, mp 177
1
3
°C (dec).; H-mr (300 MHz, CDCl ): δ 7.30 (d, J = 3.3 Hz, 1 H,
3
3
3
5'-H), 7.58 (t, J = 9.7 Hz, 1 H, 5-H), 7.63 (t, J = 9,7 Hz, 1 H, 7-
H), 7.90 (t, J = 9.7 Hz, 1 H, 6-H), 7.97 (d, J = 3.3 Hz, 1 H, 4'-
H), 8.38 (d, J = 9.8 Hz, 1 H, 4-H), 8.58 (s, 1 H, 2-H), 9.19 (d, J
= 9.8 Hz, 1 H, 8-H); C nmr (75 MHz, CDCl ): δ = 82.73 (C-3),
1
3
3
(4.21), 230 (4.30), 294 (4.21), 343 (3.87), 477 (4.40). H nmr
3
3
3
3
(300 MHz, CDCl ): δ 7.31 (d, J =3.4 Hz, 1 H, 5'-H), 7.49 (t, J
3
3
3
13
= 9.7 Hz, 1 H, 5-H), 7.55 (t, J = 9,7 Hz, 1 H, 7-H), 7.86 (t, J =
9.6 Hz, 1 H, 6-H), 7.96 (d, J = 3.3 Hz, 2H, 4'-H), 8.27 (s, 1H, 2-
H), 8.47 (d, J = 9.3 Hz, 1 H, 4-H), 9.19 (d, J = 9.6 Hz, 1 H, 8-
H); C nmr (75 MHz, CDCl ): δ 119.1 (C-5'), 123.3 (C-3), 124.0
3
3
119.2 (C-5'), 126.2 (C-2), 128.8 (C-7), 129.3 (C-5), 135.5 (C-8),
141.2 (C-4), 141.5 (C-6), 138.8 (C-8a), 143.5 (C-4'), 144.0 (C-
3
3
13
+
3a), 144.5 (C-1), 179.2 (C-2'); ms: m/z 365 ([M] , 8), 336 (10),
3
(C-2), 128.4 (C-5), 129.0 (C-7), 136.4 (C-8), 136.8 (C-4), 139.1
(C-8a), 139.5 (C-3a), 140.7 (C-1), 141.6 (C-6), 143.4 (C-4'),
179.2 (C-2'); ms: m/z 275 (6), 273 ([M] , 18), 246(7), 244 (21),
253 (30), 210 (62), 140 (23), 126 (100).
Anal. Calcd. for C H IN S: C, 42.63; H, 2.48; I, 34.68; N,
13
8
3
+
11.48; S, 8.74. Found: C, 42.66; H, 2.52: I, 34.57; N, 11.52; S,
8.73.
210 (67), 163 (21), 161 (62), 140 (48), 126 (100).
Anal. Calcd. for C H ClN S: C, 56.93; H, 3.31; Cl, 12.76; N,
15.33; S, 11.67. Found: C, 56.89; H, 3.25; Cl, 12.83; N, 15.39; S,
11.64.
13
8
3
5-Iodo-2-[(3-iodoazulen-1-yl)diazenyl]-1,3-thiazole, (8).
This compound was obtained as dark brown crystals, mp 190
°C; uv (methanol): λ max (lg ε) 226 (4.22), 255 (4.10), 306
3-(1,3-Thiazol-2yldiazenyl)azulen-1-yl Thiocyanate, (29SCN).
1
(4.20), 360 (3.78), 506 (4.36); H nmr (300 MHz, CDCl ): δ 7.96
3
3
3
The azo compound 5H (120 mg, 0.5 mmol) was dissolved in
DCM (3 mL) and treated with lead thiocyanide (320 mg, 0.25
mmol) and bromine (160 mg, 0.5 mmol). The reaction mixture
was stirred for 30 min. at room temperature, the solvent was
vaporized to dryness and the residue was separated by chro-
matography on alumina with n-pentane:DCM (1:1). Four colored
fractions were obtained: fraction 1, unidentified products (16
mg), fraction 2, 3-bromoazulene (60 mg, 0.19 mmol), fraction 3,
compound 29SCN (28 mg, 0.094 mmol, 28 %) and the fraction 4,
starting material 5H (32 mg, 0.133 mmol, recovered 67 %). The
compound (29SCN) was obtained as dark brown crystals, mp
222-; ir 730, 750, 840, 885, 1015, 1130, 1210, 1280, 1305, 1330,
(s, 1 H, 4'-H), 7.61 (t, J = 9.7 Hz, 1 H, 5-H), 7.62 (t, J = 9,7 Hz,
1 H, 7-H), 7.90 (t, J = 9.7 Hz, 1 H, 6-H), 8.38 (d, J = 9.6 Hz, 1
H, 4-H), 8.53 (s, 1H, 2-H), 9.11 (d, J = 9.9 Hz, 1 H, 8-H); ms:
m/z 491 ([M] , 5), 365 (7), 336 (13), 253 (18), 210 (32), 140
3
3
3
+
(37), 128 (42), 126 (100).
Anal. Calcd. for C H I N S: C, 31.72; H, 1.64; I, 51.60; N,
13 7 2
3
8.54; S, 6.50. Found: C, 31.75: H, 1.69: I, 51.41: N, 8.60; S, 6.55.
Methylation of Compound 5H.
The azo compound 5H, (48 mg, 0.2 mmol) was dissolved in 10
mL of chloroform and 1.5 mL methyl iodide. The reaction mix-
ture was refluxed with magnetic stirring for 2 hour and a supple-
mentary amount of methyl iodide (1.5 mL) was added after 1
hour to compensate its elimination through evaporation. The
reaction mixture was evaporated under vacuum to dryness and
the residue was chromatographed on an alumina. Three coloured
fractions were collected: the first fraction, eluted with ethyl
acetate was the starting material, (13 mg, unreacted compound 27
-1
1380, 1420, 1450, 1480, 1570, 2160, 2370 cm ; UV (methanol):
λ max (lg ε) 228 (4.41), 243sh (4.16), 293 (4.20), 340 (3.81), 466
1
3
(4.31); H nmr (300 MHz, CDCl : δ 7.35 (d, J = 3.3 Hz, 1 H,
3
3
3
4'-H), 7.70 (t, J = 10.1 Hz, 1 H, 5-H), 7.73 (t, J = 10.1 Hz, 1 H,
7-H), 8.01 (t, J = 9.8 Hz, 1 H, 6-H), 7.99 (d, J = 3.3 Hz, 1 H, 5'-
H), 8.53 (s, 1 H, 2-H), 8.71 (d, J = 9.6 Hz, 1 H, 4-H), 9.29 (d,
3
3
3

1004
A. C. Razus, L. Birzan, S. Nae, M. N. Surugiu and V. Cimpeanu
Vol. 40
cyanatoazulene with diverse diazonium salts when a high amount of sym-
metrical dithioproduct was obtained; A. G. Anderson Jr. and R. N.
McDonald, J. Am. Chem. Soc., 81, 5669 (1959).
[10] Ya. A. Miller and J. Putnins, Latv. PSR Zinat, Akad. Vestis,
Kim. Ser., 526 (1975), Chem. Abstr., 84, 159169t (1976).
[11] A. G. Anderson and B. M. Steckler, J. Am. Chem. Soc., 81,
4941 (1959); K. Hafner, H. Palzelt and H. Kaiser, Liebigs Ann. Chem.,
656, 24 (1962) [13].
[12] The direct iodination of azulene-1-azoarenes failed and only a
complex with iodine was obtained. Therefore, the iodinated compounds
were obtained by the reaction with ICl or by the substitution of HgCl
group with iodine, see A. C. Razus, L. Birzan, S. A. Razus, and V. Horga,
Rev. Roum. Chim., 44, 235 (1999) and L. Birzan, Ph. D. Dissertation,
Bucharest, 2000.
[13] H. Beyer and H. Drews, Chem. Ber., 87, 1500 (1954).
[14] At the dilution of the acidic solution a green color appears
proving the probable formation of the 5-nitroso derivatives in a reversible
amino nitrosation. The green spot observed by thin layer chromatography
of the reaction mixture indicated also the generation of a little amount of
nitroso derivative which polymerizes at solvent vaporization.
[15] A. C. Razus, J. Chem. Soc., Perkin Trans. 1, 981 (2000).
[16] A. Dornow, H. H. Marquardt and H. Paucksch, Chem. Ber.,
97, 2165 (1964).
%); the second fraction was an unidentified yellow product
(5 mg) and the third violet fraction, eluted with methanol, was the
methylated product 28 (13 mg, 23 %). 2-[Azulen-1-yl)diazenyl]-
3-methyl-1,3-thiazol-3-ium iodide, 28, was obtained as green
crystals, mp 272 °C; ir 615, 645, 725, 760, 780, 840, 890, 980,
1020, 1100, 1140, 1210, 1280, 1290, 1325, 1390, 1440, 1515,
-1
1550, 1610, 2350, 2950, 3050 cm ; uv (methanol): λ max (lg ε)
1
233 (4.44), 255 (4.12), 298 (3.95), 338 (3.66), 561 (4.40); H nmr
3
(300 MHz, DMSO-d ): δ 4.14 (s, 3 H, Me), 7.84 (d, J = 4.1 Hz,
6
3
3
1 H, 4'-H), 7.90 (d, J = 4.5 Hz, 1 H, 3-H), 8.16 (d, J = 4.3 Hz, 1
H, 5'-H), 8.24 (t, J = 9.7 Hz, 1 H, 5-H), 8.29 (d, J = 4.5 Hz, 1 H,
2-H), 8.34 (t, J = 9,7 Hz, 1 H, 7-H), 8.47 (t, J = 9.8 Hz ,1 H, 6-
H), 8.92 (d, J = 9.6 Hz, 1 H, 4-H), 9.28 (d, J = 9.8 Hz,1 H, 8-H);
3
3
3
3
3
3
13
C nmr (75 MHz, DMSO-d ): δ 37.34 (N-Me), 117.4 (C-5'),
6
125.2 (C-3), 127.0 (C-2), 130.0 (C-5, C-7), 135.4 (C-8), 137.9
(C-4), 138.3 (C-4'), 138.4 (C-8a), 142.7 (C-6), 143.0 (C-3a),
145.1 (C-1), 176.1 (C-2').
Anal. Calcd. for C
H IN S: C, 44.10; H, 3.17; I, 33.31; N,
14 12 3
11.03; S, 8.39. Found: C, 44.10; H, 3.18; I, 33.29; N, 11.01; S,
8.42.
[17] H. Beyer and G. Ruhlig, Chem. Ber., 89, 107 (1956).
[18] H. G. O. Beker, H. Bottker and H. Haufe, J. Prakt. Chem.,
312, 433 (1970).
REFERENCES AND NOTES
[19] S. Laltha, V. Kannappan and M. Nanjan, J. Indian J. Chem.,
20A, 714 (1981).
[20] R. A. Bartshc, Y. Hayashi, J-H.Kim and M. Ikeda, J. Am.
Chem. Soc., 123, 7479 (2001).
[a] For the sake of simplicity, the trivial names for azo com-
pounds were prefered in the descriptive part of the paper.
[b] Corresponding author: e-mail: acrazus@cco.ro; Fax 0040
213121601.
[21] G. Alberti, A. Cercani and G. Sen, Chem. Ind. (Milan), 55,
801 (1973). J. G. Fischer and J. M. Straley, US Patent 3,928,311, (1975).
R. Mohr, E. Mundlos and K. Hohmann, German Patent 2,522,174
(1976). E. Mundlos, R. Mohr, E. Feess and K. Hohmann, German Patent
2,553,508, (1977). B. Parton, British Patent, 2028856 (1980), Chem.
[1a] A. C. Razus, L. Birzan, S. Nae, S. A. Razus, V. Cimpeanu and
C. Stanciu, Synth. Commun., 32, 825 (2001); [b] A. C. Razus, L. Birzan,
S. Nae, C. Nitu and V. Cimpeanu, Rev. Chim.(Buc), 52, 188 (2001); [c] A.
C. Razus, L. Birzan, S. Nae, L. Cristian, F. Chiraleu and V. Cimpeanu,
Dyes Pigm., 57, 223 (2003).
Abstr. 94, 4937z (1981).
[2] M. Nakagawa, M. Rikukawa, M. Watanabe, K. Sanui and N.
Ogata, Bull. Chem. Soc. Jpn., 70, 737 (1997).
[3] Other azulene-1-azoarenes were used for the generation of an
electrically conducting polymer film at the electrode surface: N. D. Totir,
A. C. Razus, C. Lete, C. Nitu and S. Lupu, 81.Bunsen Kolloquium,
September, 2002, Dresden.
-1
[22] D°
(kj.mol ): C-N 754; N-Cl 334; N-Br 276; N-S 464.
298
th
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