Unexpected formation of naphtho[2,1-d]thiazole-6,9-dione from 3,5,6-trichloro-2-[2-(E-phenyldiazenyl)-thiazol-5-yl]-1,4-benzoquinone

Full text of DOI:10.1007/s10593-013-1177-5

Chemistry of Heterocyclic Compounds, Vol. 48, No. 10, January, 2013 (Russian Original Vol. 48, No. 10, October, 2012)
UNEXPECTED FORMATION OF NAPHTHO[2,1-d]THIAZOLE-
6,9-DIONE FROM 3,5,6-TRICHLORO-2-[2-(E-PHENYLDIAZENYL)-
THIAZOL-5-YL]-1,4-BENZOQUINONE
N. Batenko,1* S. Belyakov,2 and R. Valters1
Keywords: 1,4-benzoquinone, naphtho[2,1-d]thiazole-6,9-dione, vinylquinones, phenyldiazenyl
derivatives.
In previous work [1, 2], we showed that the reaction of 2-(2-N,N-dialkylaminothiazol-5-yl)-3,5,6-trichloro-
1,4-benzoquinones and a C-nucleophile, namely, N,N-diethyl-N-vinyl amine, proceeds with substitution of the
chlorine atom at C-5 in the benzoquinone ring, leading to the corresponding diethylaminovinyl derivative. In a
continuation of our studies on the synthesis of heterocyclic quinones [1, 2], we carried out a reaction between
3,5,6-trichloro-2-[2-(E-phenyldiazenyl)thiazol-5-yl]-1,4-benzoquinone (1) [3] and N,N-diethyl-N-vinylamine, with
the latter obtained in situ from diethylamine and acetaldehyde. However, we obtained a cyclization product,
namely, 7,8-dichloro-2-(E-phenyldiazenyl)naphtho[2,1-d]thiazole-6,9-dione (3) instead of the expected 5-diethyl-
aminovinylbenzoquinone 2.
Ph
Ph
N
N
N
N
N
N
O
O
S
O
O
S
Et2NH
Cl
Cl
Cl
Cl
MeCHO
NEt2
Cl
A
1
Ph
N
N
N
Ph
O
S
N
N
N
Cl
O
O
S
Cl
Cl
Et2N
Cl
O
2
3
_______
*To whom correspondence should be addressed, e-mail: nelli.batenko@rtu.lv.
1Riga Technical University, 14/24, Azenes St., Riga LV-1048, Latvia.
2Latvian Institute of Organic Chemistry, 21 Aizkraukles St., Riga LV-1006, Latvia; e-mail: serg@osi.lv.
_________________________________________________________________________________________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1683-1685, October, 2012.
Original article submitted September 7, 2012.
0009-3122/13/4810-1571©2013 Springer Science+Business Media New York
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In all likelihood, this reaction proceeds through substitution of the chlorine atom at the C-3 atom of the
benzoquinone ring to give intermediate A, followed by formation of the aromatic system 3. The compounds
studied in our previous work [1, 2], for which substitution of the chlorine atom at the position C-5 in the
benzoquinone ring was observed, had electron-donor dialkylamino groups at the position C-2 in the thiazole
ring. The presence of an electron-withdrawing phenyldiazenyl substituent at the position C-2 in the thiazole ring
is presumably the major factor shifting the reaction toward the formation of naphthothiazole 3. The structure of
naphthothiazole 3 was confirmed by X-ray diffraction structural analysis (Fig. 1).
The X-ray diffraction structural analysis indicates that the atoms lie in a single plane and conjugation
encompasses the entire molecule of naphthothiazole 3. A strong O···Cl–Csp2 halogen bond was discovered in
this crystal structure. The O(22)···Cl(23) distance is 3.221(3) Å, and the O(22)···Cl(23)–C(7) angle is 165.6(2)°.
Centrosymmetric molecular dimers are formed by means of this bond in the crystal. We should note that the
other chlorine atom in this molecule, namely, Cl(24), does not participate in any sigma-hole interactions. This
accounts for the difference in the lengths of the C–Cl bonds in naphthothiazole 3. Thus, the C(7)–Cl(23) bond
length is 1.706(3) Å, while the C(8)–Cl(24) bond length is 1.733(3) Å. An intermolecular π-π interaction is also
observed in this crystal structure. Molecules of naphthothiazole 3 form stacks along the monoclinic axis. The
distance between the planes of adjacent molecules in a stack is 3.351 Å. The minimal intermolecular atom-atom
contact between C(11) and C(17) in the stack is 3.392(4) Å.
Fig. 1. Molecular structure of naphthothiazole 3 with atoms representated by thermal vibration ellipsoids of
50% probability.
The IR spectrum was recorded on a Thermo Electron Nicolet 5700 spectrometer for KBr pellets. The
1
UV spectrum was recorded on a Perkin Elmer Lambda 35 spectrometer in acetonitrile solution. The H NMR
spectrum was recorded on a Bruker Avance 300 spectrometer (300 MHz) in CDCl3 with HMDS as internal
standard (δ 0.05 ppm). The elemental analysis was carried out on a Carlo Erba EA1108 Elemental Analyzer.
The melting points were determined on a Kruss KSP II melting point meter. The course of the reaction and
purity of the product were checked by thin-layer chromatography on Merck F254 plates with visualization by
UV light.
7,8-Dichloro-2-(E-phenyldiazenyl)naphtho[2,1-d]thiazole-6,9-dione (3). Acetaldehyde (0.17 ml,
3 mmol) was added to a solution of the trichlorobenzoquinone derivative 1 (0.40 g, 1 mmol) in toluene (30 ml),
and then diethylamine (0.21 ml, 2 mmol) was added dropwise with stirring. The mixture was stirred at room
temperature for 2 h, then evaporated at reduced pressure. The residue was separated on silica gel column with
toluene as eluent. Yield 0.14 g (37%). Orange crystals; mp 156-158ºC (toluene). IR spectrum, ν, cm-1: 1503,
1
1567, 1591, 1663, 1676, 2926. UV spectrum, λmax, nm (log ε): 335 (4.29), 412 (4.14). H NMR spectrum, δ,
ppm (J, Hz): 7.60-7.69 (3H, m, H Ph); 8.15-8.22 (2H, m, H Ph); 8.40 (1H, d, J = 8.4, H-5); 8.55 (1H, d, J = 8.4,
H-4). Found, %: C 52.74; H 1.79; N 10.85. C17H7Cl2N3O2S. Calculated, %: C 52.59; H 1.82; N 10.82.
X-ray Diffraction Structural Investigation of Naphthothiazole 3. Monoclinic monocrystals of
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naphthothiazole 3 were obtained by crystallization from toluene. The unit cell parameters of the crystal lattice
were as follows: a 14.694(2), b 6.992(1), c 16.664(2) Å, β 111.74(5)°, V 1590.3(4); Z 4; μ 0.56 mm-1; space
group P21/a. The X-ray diffraction analysis was carried out on a Nonius KappaCCD diffractometer at -100°C
using molybdenum radiation (λ = 0.71073 Å). A total of 1998 independent reflections with I > 3σ(I) of
3904 measured reflections up to 2θmax 55° were used in the calculations. The structure was solved by the direct
method [4] and refined by the full-matrix method of least squares [5]. All the non-hydrogen atoms were refined
in anisotropic approximation, and the hydrogen atoms were refined using the "rider" model. The final
probability factor was equal to 0.053. The complete data set for this crystal structure has been deposited at the
Cambridge Crystallographic Data Center (CCDC deposit 899510).
This work was carried out with the financial support of the Latvian Science Council (grant 09/1617).
REFERENCES
1.
N. G. Batenko, R. Valters, and G. Karlivans, Khim. Geterotsikl. Soedin., 835 (2000). [Chem.
Heterocycl. Compd., 36, 733 (2000)].
2.
3.
N. G. Batenko, G. A. Karlivans, and R. E. Valters, Heterocycles, 65, 1569 (2005).
N. Batenko, S. Belyakov, and R. Valters, Khim. Geterotsikl. Soedin., 766 (2009). [Chem. Heterocycl.
Compd., 45, 606 (2009)].
4.
5.
A. Altomare, G. Cascarano, G. Giacovazzo, A. Guagliardi, M. C. Burla, G. Polidori, and M. Camalli,
J. Appl. Crystallogr., 27, 435 (1994).
S. Mackay, W. Dong, C. Edwards, A. Henderson, C. J. Gilmore, N. Stewart, K. Shankland, and
A. Donald, maXus, Integrated Crystallography Software, Bruker-Nonius and University of Glasgow
(2003).
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