Dithiocarbamates, thiocarbamic esters, dithiocarboimidates, guanidines, thioureas, isothioureas, and tetraazathiapentalene derived from 2-aminobenzothiazole

Article abstract of DOI:10.1002/ejoc.200400305

Reactions between CS₂ and the exocyclic amino groups of 2-aminobenzothiazoles gave series of molecules bearing thiourea, isothiourea, dithiocarbamate, dithiocarboimine, dimethyldithiocarbamate, methyldithiocarbamate, S-CH₃ and O-alkyl thiocarbarnic ester, and guanidine groups. Preferred tautomers and conformers were determined. Most compounds present coordinative bonds between the endocyclic sulfur atom, which behaves as a Lewis acid, and oxygen, nitrogen, and sulfur acting as bases. A new dibenzothiazolyltetraazathiapentalene containing a T-shaped hypervalent sulfur atom and displaying "single bond-no bond resonance" is discussed. X-ray structures of eleven compounds are reported. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.

Full text of DOI:10.1002/ejoc.200400305

FULL PAPER
Dithiocarbamates, Thiocarbamic Esters, Dithiocarboimidates, Guanidines,
Thioureas, Isothioureas, and Tetraazathiapentalene Derived from
2-Aminobenzothiazole
[a]
[b]
[a]
[a]
´
´
´
Fabiola Tellez, Alejandro Cruz, Horacio Lopez-Sandoval, Iris Ramos-Garcıa,
Martha Gayosso,[a] R. Nely Castillo-Sierra,[b] Brenda Paz-Michel,[a] Heinrich Nöth,[c]
Angelina Flores-Parra,[a] and Rosalinda Contreras*[a]
Keywords: 2-Aminobenzothiazole / Dibenzothiazolyltetraazathiapentalene / Electrophilic and nucleophilic sulfur atoms
Reactions between CS2 and the exocyclic amino groups of 2-
aminobenzothiazoles gave series of molecules bearing thio-
urea, isothiourea, dithiocarbamate, dithiocarboimine, di-
methyldithiocarbamate, methyldithiocarbamate, S-CH3 and
O-alkyl thiocarbamic ester, and guanidine groups. Preferred
tautomers and conformers were determined. Most com-
pounds present coordinative bonds between the endocyclic
sulfur atom, which behaves as a Lewis acid, and oxygen, ni-
trogen, and sulfur acting as bases. A new dibenzothiazolyl-
tetraazathiapentalene containing a T-shaped hypervalent
sulfur atom and displaying ‘‘single bond-no bond resonance’’
is discussed. X-ray structures of eleven compounds are re-
ported.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2004)
Introduction
activity,[6Ϫ9] and in their use as building units in supramol-
ecular structures or in materials science. The investigated
compounds can be described by many different conformers
and tautomers, and these complex systems merit careful
analysis in order to understand the structural implications
of weak interactions such as hydrogen bonds and Lewis
acid/base contacts giving ordered and rigid structures.[10,11]
In particular, we are interested in studying weak interac-
tions at sulfur atoms, which can have significant influence,
not always recognized, in the preferred conformers and in
the structures of molecular conglomerates. The sulfur
atoms present coordinating contacts with lone pair-donat-
We are currently investigating the structures of biologi-
cally active, aromatic nitrogenated heterocycles[1Ϫ4] with
free lone pairs, labile hydrogen atoms, and planar delo-
calized acyclic groups. Here we report the preparation and
a structural study of a series of compounds, including four-
teen new ones, derived from 2-aminobenzothiazole (1) and
5,7-di-tert-butyl-2-aminobenzothiazole (1a). The studied
compounds have functional groups such as guanidine, thio-
urea, isothiourea, dithiocarbamate, dithiocarboimine, di-
methyl dithiocarbamate, methyldithiocarbamate, and S-
methyl and O-alkyl thiocarbamic esters. The new com-
pounds have very reactive functional groups that can be
used for the synthesis of more complex molecules, together
with rigid frameworks with several lone pairs available for
coordination, and so are potentially interesting ligands for
metallic compounds. X-ray diffraction structures of eleven
compounds are analyzed.
˚
ing atoms, with atomic distances of less than 3.70 A (for
[12Ϫ14]
˚
˚
S···S; 3.25 A for S···O, and 3.35 A for S···N).
The
divalent sulfur in these contacts may act either as a donor
on an axis perpendicular to the plane of the XϪSϪZ sulfur
bonds or as a Lewis acid following the axis of one of the
two XϪS or SϪZ bonds (Scheme 1, a). S···S interactions in
particular can be regarded as acceptor-donor pairs,[14,15]
while S···O interactions have biological relevance.[12,16Ϫ18]
The relevance of the studied molecules lies in their
‘‘Y-type’’ aromatic conjugation,[5] in their biological
[a]
´
´
Departamento de Quımica, Centro de Investigacion y de
Estudios Avanzados del IPN,
´
A. P. 14-740, CP 07000, D. F., Mexico
[b]
[c]
´
Departamento
de
Quımica,
Unidad
Profesional
´
Interdisciplinaria de Biotecnologıa del IPN,
Av. Acueducto de Guadalupe, s/n Col. Barrio la Laguna,
´
´
Ticoman, D.F. Mexico
Department de Chemie, Ludwig-Maximilians Universität,
Butenandt-Straße 5Ϫ13 (Haus D), 81377 München, Germany
Scheme 1
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R. Contreras et al.
FULL PAPER
This report describes a new and original hexacyclic boimidates 2 and N-(benzothiazolyl)dithiocarbamates 3,
pentalene bearing a hypervalent sulfur atom, analogous bi- intermediates for compounds 4 and 5, which are starting
cyclic and tetracyclic structures being very scarce.[19] Sulfur materials for more complex molecules through substitution
atoms in such compounds are tricoordinate with T-shape of their thiomethyl groups.
geometries and are bonded to one carbon and two nitrogen
Compounds 2-Na and 3-Na have been reported without
atoms,[20] presenting NϪSϪN linear arrangements with characterization.[26] The synthetic interest of compounds 2
bond orders of less than one[21] and delocalized systems and 3 stimulated us to analyze their structures by NMR (2-
with single bond-no bond resonance (Scheme 1, b). The Na, 2-K, 3-Na, 3-Li) and X-ray diffraction (2-Na and 3-
scarcity of NMR spectroscopic data for such compounds is Li). The preparation of 2 and 3 depends on the reaction
due to their low solubilities.[23Ϫ25] The metallic character
of the sulfur in tetraazathiapentalenes is evidenced by its
substitution by palladium and platinum, giving metallic
compounds which acquire square planar geometry.[22]
Results and Discussion
Insertion of CS2 at the exocyclic nitrogen atoms of 2-
aminobenzothiazole (1) and 3,5-di-tert-butyl-2-aminoben-
zothiazole (1a) in the presence of a base was used for the
preparation of a series of compounds. Compound 1 is com-
mercially available, whereas 1a was obtained from 2,5-di-
tert-butylaniline, KSCN, and Br2 in acetic acid (Scheme 2).
Scheme 2
Treatment of these compounds with CS2 in the presence
of a base (Scheme 3) afforded N-(benzothiazolyl)dithiocar- Figure 1. Molecular structure of compound 3-Na
Scheme 3
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A Range of Compounds Derived from 2-Aminobenzothiazole
FULL PAPER
Figure 3. Molecular structure of compound 4; intra- and inter-
molecular interactions are shown
distinguished by their 13C data [C11 appears at δ ϭ
193 ppm in 2-Na, but at δ ϭ 213.7 ppm in 3-Na]. The 2-
Na/3-Na mixture was crystallized from ethanol/water
Figure 2. Molecular structure of compound 3-Li
stoichiometry and on the nature of the base. Treatment of (50:50), and the obtained crystals (3-Na) were analyzed by
1 with two equivalents of NaOH and CS2 and subsequent X-ray diffraction (Figure 1).
addition of CHCl3 gave a yellow precipitate, its 1H and 13C
Condensation reactions performed with LiOH and with
NMR spectra indicating a mixture (60:40) of the two so- KOH selectively afforded dithiocarboimidate 3-Li and di-
dium compounds 2-Na and 3-Na. The two products can be thiocarbamate 2-K, respectively (Scheme 3 and Figure 2).
Figure 4. Molecular structure of compound 5; intra- and intermolecular interactions are shown
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Anions 2 and 3 reacted differently in methylation reactions
to give compounds 4 and 5, respectively,[26] and these are
useful precursors for functionalized heterocycles.[27Ϫ36]
Compound 2-K selectively afforded dimethyl compounds 4
and 4a, whereas the S-methyl ester 5 could be prepared in
high yield by methylation of compound 3-Li (Scheme 3).
Use of the 2-Na/3-Na mixture gave a mixture of 4 and 5,
from which 4 could be separated by recrystallization from
methanol. In the literature the characterization of 4 and
1
5 was only supported by H NMR and mass spectra.[26]
Compounds 4 and 5 were crystallized from methanol and
ethanol, respectively; both are planar with U-shaped arms
(Figures 3 and 4). It is interesting that the thione group in
3 or 5 prefers to be cis to the endocyclic CϪS bond,
whereas in compounds 2 and 4 the endocyclic imine bond
is cis to the exocyclic CϪS bond. On treatment of 2-Na
with CH3I a second compound 7 was isolated from the
mother liquors, and was crystallized from CH3OH. It is as-
sumed that 7 arises from methylation of the hydrolyzed dis-
odium salt 6 (Scheme 3). The solid-state structure is shown
in Figure 5.
Scheme 4
1
hydrogen bonds, as deduced from their high-frequency H
A demonstration of the synthetic use of compound 5 can NMR signals [12, δ ϭ 10.64; 13, 10.70; 14, 9.6 ppm]. Com-
be seen in the preparation of thioureas 8 and 9, in its reac- pound 9 has two NϪH resonances at δ ϭ 9.83 and
tions with the corresponding amines, and in the synthesis 12.04 ppm, the first (H13) a quadruplet because of coupling
of thiocarbamic esters 10 and 11 in the presence of the cor- to the NCH3 group. In their 13C NMR spectra, compounds
responding alcohols and mercuric acetate as a catalyst. On 8Ϫ11 ([D6]DMSO) and 12Ϫ14 (CDCl3) present broad sig-
the other hand, isothioureas 12 and 13 and guanidine 14 nals for C2, C8, C9, and C11, due to the dynamic behavior
1
can be prepared by treatment of compound 4 with the cor- of the arms. The H NMR spectra of compounds 8, 10,
responding amines in ethanol at reflux (Scheme 4).
and 11 show broad signals above δ ϭ 10 ppm for NϪH
Compounds 9 and 12Ϫ14 have U conformations with N3 [8, δ ϭ 10.86; 10, 13.43; 11, 13.34 ppm] indicating strong
and N13 in cis arrangements stabilized by N13ϪH13···N3 intermolecular bonds. The solid-state structures for com-
Figure 5. Molecular structure of compound 7 showing intra- and intermolecular interactions
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A Range of Compounds Derived from 2-Aminobenzothiazole
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pounds 7Ϫ11 and 13 were determined (Figures 6, 7, 8.
and Figure 9).
Figure 8. Molecular structure of compound 11 showing intra- and
intermolecular interactions
Figure 6. Molecular structure of compound 8 and intra- and inter-
molecular hydrogen bonds
Figure 7. Molecular structure of compound 9 and intra- and intermolecular interactions
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R. Contreras et al.
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can be deduced from the solid-state structures of com-
pounds 5, 8, 10, and 11, which each have a CϭS double
bond cis to the endocyclic CϪS bond. The proposed con-
formation is also supported by the fact that the more stable
isomer for thiathiophthenes has the three sulfur atoms in-
teracting in a linear rearrangement.[36]
Deprotonation of 15 was performed with NaH in THF
(15-Na) and its NMR spectra were determined at 80 °C,
due to its better solubility at this temperature. The 13C sig-
nals were shifted to lower frequencies (C9 at δ ϭ 151.0, C2
at 171.8, and C11 at 188.4 ppm) as would be expected for
the increase in ring electronic density due to the dianion’s
two extra free lone pairs.[35] The IR band for NϪH disap-
peared.
Oxidation of 15 with N-bromosuccinimide afforded the
crystalline tetraazathiapentalene 16 (Scheme 5). The 1H
spectrum of 16 (in DMSO) does not show the N-H signal.
In the 13C spectrum at room temperature only seven signals
are observed; C11 is not detected, but at 120 °C the signal
1
emerges at δ ϭ 187.4 ppm. The equivalence of the H sig-
nals of the two 2-aminobenzothiazole fragments shows that
a delocalized system with ‘‘single bond-no bond resonance’’
is present in solution (Scheme 1).
The fact that the molecular peak (340) for 16 is the par-
ent peak in its mass spectrum indicates that it is very stable.
According to its crystalline structure (Figure 10) it can be
viewed as a tetraazathiapentalene. It has a T-shaped π-hyp-
ervalent tricoordinate sulfur atom (10-S-3), connected in a
linear arrangement with two nitrogen atoms.[5]
Treatment of compounds 4 (or 4a) with two equivalents
of 1 (or 1a) gave the N,NЈ,NЈЈ-tris(benzothiazol-2-yl)guani-
dines 17 (or 17a). Treatment of 4 with two equivalents of
1a gave the mixed compound 17b (Scheme 6). Compound
17 is only partially soluble in DMSO at room temp., so
NMR spectra were obtained at 120 °C, at which only one
type of benzothiazole fragment was detected. The N-H
gives a broad band at δ ϭ 12.9 ppm. The 13C spectrum also
presents broad signals, indicating a dynamic equilibrium be-
tween three planar and delocalized tautomers through the
of the two N-H moieties between the three endocyclic nitro-
gen atoms and between their conformers a or b. Conformer
a could be more stable due to a stabilizing N···S interaction
instead of N···N repulsions.
Figure 9. Molecular structure of compound 13
Treatment of compound 1 with 5 gave N,NЈ-bis(benzothi-
azol-2-yl)thiourea (15; Scheme 5). Compound 15 can be
represented by five tautomers each having one or two intra-
molecular hydrogen bonds in a planar rearrangement. At
the same time, each tautomer of 15 may have several con-
formers; six conformers can be written for the tautomer
represented in Scheme 5, for example. In spite of this, com-
pound 15 seems to exist in a preferred conformation.
Compound 15 is not very soluble in [D6]DMSO, so its
13C spectrum was recorded at 120°; the two benzothiazole
rings appear equivalent in the NMR spectra, and C11 and
C2 have resonances at higher frequencies (δ ϭ 182.2 and
163.8 ppm, respectively). It can be deduced that the hydro-
gen atom is at N10, since the chemical shift of C9 at δ ϭ
143.8 ppm indicates that N3 is unprotonated.[35] On the
other hand, the high-frequency NϪH signal (δ
ϭ
The more soluble compound 17a was analyzed by NMR
12.57 ppm) shows that it is involved in a strong intermolec- in CDCl3 by some vt experiments. At Ϫ60 °C the 13C spec-
ular hydrogen bond. In the solid state, the IR does not show trum showed 22 signals in the aromatic region for three
SϪH bands, while a strong band for CϭS was found at different benzothiazole moieties. The resonances for the
1250 cmϪ1. The band for NϪH is characteristic of a hydro- benzothiazol-2-ylidene fragment were assigned by compari-
gen bond (ν˜ ϭ 3265, sharp). A conjecture for the structure son with 4a, while the two other fragments showed fairly
Scheme 5
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A Range of Compounds Derived from 2-Aminobenzothiazole
Figure 10. Molecular structure of compound 16
Scheme 6
FULL PAPER
similar signals that were not completely assigned. It is de- geometry for the lithium atom, which is bonded through
duced that, at this temperature, tautomer a with a preferred the benzothiazole nitrogen, as observed in similar
conformation is frozen; effectively two different NϪH com- heterocycles,[40Ϫ43] and to the carbonyl groups of two N,N-
ponents were detected at δ ϭ 13.37 and 14.08 ppm.
dimethylformamide molecules; a fourth coordination is pro-
vided by a water molecule, which forms an intermolecular
hydrogen bond with one sulfur atom from another molecule
(Figure 2). The lithium does not interact with the sulfur
atoms, contrary to what has been observed in analogous
systems.[44Ϫ46] The two formamide and two water molecules
determine the intra- and intermolecular interactions in the
cell. An intramolecular hydrogen bond is found for
X-ray Analyses
Compound 3-Na has a polymeric arrangement (Figure 1)
with only one sodium atom per dithiocarbamate molecule.
Each sodium is bonded to two dithiocarbamate molecules
and each dithiocarbamate is bonded to two sodium atoms;
one is coordinated by the thione group and the other by
the N3 atom of the benzothiazole ring. The sodium atom is
hexacoordinate with a distorted octahedral geometry. Each
sodium atom is linked to four water molecules, two of them
bridging two sodium atoms in a four-membered ring with a
˚
O19ϪHN10 [2.01 A, 166.1°]. The S1ϪC2ϪN10ϪC11ϪS13
fragment adopts a U-conformation allowing a short
˚
sulfur···sulfur contact, with the S1···S13 distance 2.975 A
˚
(ΣrvdW 3.70 A) and the C8ϪS1···S13 angle 166.83°. The
˚
bond length difference between C11ϪS13 [1.660(4) A] and
˚
Na···Na distance of 3.623(2) A.[37Ϫ39] The distance between
C11ϪS12 [1.720(3) A] is due to coordination of S12 with
˚
two water molecules.
˚
sulfur atoms C8ϪS1···S13 is 3.022 A, and the angle is
165.53°.
Compounds 4 and 5 were crystallized from methanol and
Compound 3-Li was crystallized from a DMF/CHCl3 ethanol, respectively, and both are planar with U-shaped
mixture (50:50). The structure shows a distorted tetrahedral arms in which S13 and N3 approach one another in 4 (dis-
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˚
˚
˚
tance 2.839 A, ΣrvdW 3.35 A) and S13 and S1 (2.947 A) do Conclusion
the same in 5 (Figures 3 and 4). Compound 4 is a polymer
in which S13 atom is connected through donor and ac-
We have prepared a series of polyfunctional compounds,
which display very complex tautomeric and conformational
behavior, from 2-aminobenzothiazole. The reported mol-
ecules are quite reactive and can be used as precursors for
more complex molecules. In molecules 3Ϫ7 the endocyclic
sulfur atom behaves as a Lewis acid and is coordinated by
oxygen, nitrogen, and sulfur atoms. These stabilizing con-
tacts determine their preferred conformation. Compounds
8Ϫ15 and 17 have labile acidic NϪH protons, which partici-
pate in strong hydrogen bonds. A new dibenzothiazolylte-
traazathiapentalene 16 bearing a T-shaped hypervalent sul-
fur atom bonded to a carbon and to two nitrogen atoms
and presenting a ‘‘single bond-no bond’’ resonance struc-
ture is reported. All the studied compounds are planar and
highly delocalized molecules with carbon heteroatom alter-
nating frameworks. We are currently investigating their co-
ordination behavior with metals, and research into their
biological activity is also in progress.
ceptor interactions to two other S13 atoms (distance be-
˚
tween S13 atoms is 3.47 A and S13C···S13A···S13B angle is
71.47°; Figure 3).
In compound 5 the labile NϪH proton was found by
Fourier difference at N3, which allows intermolecular inter-
˚
actions through hydrogen bonds with N10 [2.33 A, 163.7°].
˚
The bond lengths C2ϪN10 [1.330(3) A] and N10ϪC11
˚
[1.355(3) A] indicate an electronic delocalized system (Fig-
ure 4).
Compound 7 (Figure 5) has a structure similar to that of
˚
5, Its intramolecular O···S1 distance being 2.637 A (ΣrvdW
˚
3.25 A), and intermolecular hydrogen bonds being observed
˚
between oxygen and H4 (2.50 A) and between S12 and H7B
˚
(2.92 A).
Compounds 8, 10, and 11 present planar structures with
U-conformations and short distances between S1···S13 in
their X-ray diffraction analysis (Figures 6 and 8); these dis-
˚
tances and C8ϪS1ϪS13 angles are 2.908 A and 167.10° in
˚
˚
8, 3.044 A and 165.86° in 10, and 3.003 A and 166.69° in
11. The CϪN bond lengths are characteristic of a delo-
calized system, while the C11ϪS13 bonds are typical
double bonds. In compound 8 an intramolecular hydrogen
Experimental Section
An FT IR spectrometer (PerkinϪElmer 1600) was used for ob-
bond between CH14c and N10 was found (distance 2.19 taining IR spectra of solid samples in KBr pellets (4000Ϫ400
cmϪ1). The UV/Visible spectra (diffuse reflectance, were recorded
on a Cary-5E (Varian) spectrometer. The MS spectra were obtained
by direct insertion at 20 eV in an HP 5989 spectrometer. X-ray
diffraction studies were performed with a Siemens SMART Area-
detector, CAD4, Kappa CCD. The crystal structures were deter-
mined and refined with the SHELXTL [x,y] system. Aromatic H
atoms were placed on idealized positions for (3-Na, 4, 7, 9Ϫ11, and
13), and were refined with a riding model.[47] Hydrogen atoms were
found by Fourier difference in 3-Li, 5, 8, and 16. Crystallographic
data (excluding structure factors) for the structures in this paper
have been deposited with the Cambridge Crystallographic Data
Centre as supplementary publication numbers CCDC: 229330 (for
3-Na), 229328 (for 3-Li), 229327 (for 4), 229326 (for 5), 229325 (for
7), 229320 (for 8), 229322 (for 9), 229323 (for 10), 229324 (for 11),
229321 (for 13), and 229329 (for 16). Copies of the data can be
obtained, free of charge, on applications to CCDC, 12 Union
˚
A), and an intermolecular contact between N3ϪH···S13a
˚
was observed (2.70 A).
In 10 and 11, ADAD-DADA-type dimers are formed
˚
through H4···O (2.78 and 2.86 A) and H10···N3 (2.04 and
2.17 A) interactions; this is shown for 11 in Figure 8. In
compound 11 other dimeric interactions exist through
S1···S13A and S1A···S13 contacts (3.53 A). The steric hin-
drance produced by the alkyl groups makes the molecules
of 11 form diagonal arrangements (50°).
˚
˚
The X-ray structures for 9 and 13 (Figures 7 and 9) show
intramolecular hydrogen bonds (data for 9: H13·· N3 1.94
˚
˚
A and 139.98°, 13: 2.13 A and 131.35°), which is in agree-
1
ment with their H NMR high-frequency chemical shifts.
Figure 7 shows a dimer for 9 with four contacts: two hy-
˚
drogen bonds (S12 and H10; 2.47 A, 162.98°) and two short Road, Cambridge CB2 1EZ, UK [Fax: ϩ 44-1223-336033 or
contacts (S12···S1; 3.48 A), S12 participating in a tricentric
˚
E-mail: deposit@ccdc.cam.ac.uk].
contact. In 13 a dimer is formed with molecules in perpen-
(5,7-Di-tert-butylbenzothiazol-2-yl)amine (1a): Bromine (0.78 g,
4.87 mmol) was slowly added to a mixture of 3,5-di-tert-butylani-
line (1 g, 4.87 mmol) and KSCN (0.95 g, 9.74 mmol) dissolved in
glacial acetic acid (7.74 mL). The mixture was stirred for 1 h at
dicular planes and with two hydrogen bonds between N3
˚
and H4 (distances 2.644 and 2.667 A).
The structure of compound 16 presents six planar aro-
matic fused rings, with a delocalized system existing be- room temp. After that, the solvent was evaporated, and the solid
was washed with methanol and filtered. The methanolic solution
was neutralized with an aq. solution of KOH (30%) and a colorless
solid was formed; this was filtered off and washed with cool meth-
anol (0.94 g, 74%), m.p. 162Ϫ164 °C. IR (cmϪ1): ν˜max ϭ 3449,
3403, 3290, 3095, 2963, 1639, 1536, 1393, 1325. UV/Vis: λ (nm) ϭ
378, 348 and 312. MS: m/z ϭ 262 (64) [Mϩ]; 247 (100). C15H22N2S
(266.24): calcd. C 68.66, H 8.45, N 10.68; found C 69.12, H 8.79,
N 10.68. 13C NMR (CDCl3): δ (ppm) ϭ 34.9 and 31.7 (tBu-7); 35.6
and 29.6 (tBu-5); 114.5 (C-6); 117.2 (C-4); 125.1 (C-8); 143.3 (C-
tween all CϪN bonds. The C11ϪS12 bond length [1.777(4)
A] is slightly longer than a single CϪS bond (1.75 A). The
˚
˚
˚
˚
N3ϪS12 [2.051(2) A] and N3aϪS12 [1.868(2) A] bonds are
of different length, and longer than a NϪS single bond
˚
(1.77 A), but far from the sums of the van der Waals radii
(SϪN 3.35 A). This indicates strong nitrogenϪsulfur coor-
˚
dination and hence Lewis acid behavior of the hypervalent
sulfur atom. In the cell, compound 16 is in a two-shells
arrangement, one perpendicular to another and with
1
7); 149.3 (C-5); 153.2 (C-9); 166.7 (C-2) ppm. H NMR (CDCl3):
δ (ppm) ϭ 1.36 (s, 9 H, 7-tBu); 1.44 (s, 9 H, 5-tBu); 5.53 (s br, 2
˚
N10···H7 intermolecular interactions (2.53 A).
4210
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H, N-H); 7.19 (d, J ϭ 1.8 Hz, 1 H, 6-H); 7.48(d, J ϭ 1.8 Hz, 1 (C-2); 174.7 (C-11). 1H NMR (C6D6): δ (ppm) ϭ 2.06 (s, 1 H,
4
4
3
3
H, 4-H).
SCH3); 6.99 (dd, J ϭ 8.0, 7.7 Hz, 1 H, 6-H); 7.15 (t, J ϭ 7.7 Hz,
3
3
1 H, 5-H); 7.40 (d, J ϭ 8.0 Hz, 1 H, 4-H); 8.05 (d, J ϭ 7.7 Hz, 1
Sodium Compounds 2-Na and 3-Na: NaOH solution (3.0 mL, 20 )
was added to a solution of 1 (7.5 g, 50 mmol) in DMF (50 mL).
The mixture was stirred for 45 min in an ice/water bath. After that,
CS2 (6.0 mL, 50 mmol) was added and stirring was continued for
60 min. The reaction product was poured into CHCl3. A yellow
crystalline solid was formed, was filtered off and washed, and was
found to be a mixture (40:60) of 2-Na/3-Na.
H, 7-H).
N-(5,7-Di-tert-Butylbenzothiazol-2-yl)-S,SЈ-dimethyldithiocarbo-
imine (4a): NaH (0.02 g, 0.936 mmol) was added to a solution of
compound 1a (0.12 g, 0.468 mmol) in THF (8 mL), and the mix-
ture was stirred for 4 h at room temp. CS2 (0.03 mL, 0.468 mmol)
was then added at 5 °C, the reaction mixture was stirred overnight,
and a solid precipitated. The suspension was cooled to 5 °C, CH3I
(0.06 mL, 9.36 mmol) was added, and the mixture was stirred for
2 h at room temp. Water (10 mL) was then added and the mixture
was stirred overnight. A yellow solid was filtered off and washed
with water (0.12 g, 72%). IR (cmϪ1): ν˜max ϭ 2963, 1536, 1507, 1181.
UV/Vis: λ (nm) ϭ 448, 338 nm. MS: m/z ϭ 366 (57) [Mϩ], 351
(84), 293 (100). C18H26N2S3 (370.41): calcd. C 58.97, H 7.15, N
7.64; found C 58.70, H 7.22, N 7.54. 13C NMR (CDCl3): δ (ppm) ϭ
15.9 (C-13); 35.8 and 29.6 (7-tBu); 35.0 and 31.7 (5-tBu); 117.2 (C-
6); 119.0 (C-4); 128.3 (C-8); 143.7 (C-7); 149.1 (C-5); 152.6 (C-9);
Sodium Benzothiazol-2-yldithiocarboimidate (2-Na): 13C NMR
([D6]DMSO): δ (ppm) ϭ 117.8 (C-4); 120.6 (C-7); 120.8 (C-6);
124.9 (C-5); 131.7 (C-8); 149.1 (C-9); 169.8 (C-2); 193.5 (C-11)
ppm. 1H NMR ([D6]DMSO): δ (ppm) ϭ 6.97 (s br, 1 H, 6-H); 7.16
(s br, 1 H, 5-H); 7.36 (s br, 1 H, 7-H); 7.58 (s br, 1 H, 4-H).
Sodium Benzothiazol-2-yldithiocarbamate (3-Na): 13C NMR
([D6]DMSO): δ (ppm) ϭ 120.8 (C-4); 121.2 (C-7); 122.7 (C-6);
125.7 (C-5); 131.1 (C-8); 148.1 (C-9); 161.6 (C-2); 213.7 (C-11)
ppm. 1H NMR ([D6]DMSO): δ (ppm) ϭ 7.22 (s br, 1 H, 6-H); 7.36
(s br, 1 H, 5-H); 7.69 (s br, 1 H, 7-H); 7.84 (s br, 1 H, 4-H); 11.59
(s br, 1 H, N10-H).
1
168.2 (C-2); 173.8 (C-11). H NMR (CDCl3): δ (ppm) ϭ 1.38 (s, 9
H, 7-tBu); 1.48 (s, 9 H, 5-tBu); 2.59 (s, 6 H, SCH3); 7.34 (d, J ϭ
1.6 Hz, 1 H, 6-H); 7.81(d, J ϭ 1.6 Hz, 1 H, 4-H).
4
4
Potassium Benzothiazol-2-yldithiocarboimidate (2-K): KOH (0.7 g,
12.5 mmol) was added to a solution of 1 (1.87 g, 12.5 mmol) in
DMF (15 mL), and the mixture was stirred for 45 min in an ice/
water bath. After that, CS2 (1.5 mL, 12.5 mmol) was added and
stirring was continued for 60 min. A second equivalent of KOH
(0.7 g, 12.5 mmol) was added, and after 1 h the mixture was poured
into CHCl3. The yellow precipitate was filtered off and washed
(1.32 g, 35%), m.p. 280 °C dec. IR (cmϪ1): ν˜max ϭ 1726, 1632, 1499.
UV/Vis: λ (nm) ϭ 387, 338. MS: m/z ϭ 224 (2) [Mϩ], 150 (100).
C8H4N2S3K2 (306.42), C 31.76, H 1.33, N 9.26; found C 31.32, H
1.37, N 8.77. 13C NMR ([D6]DMSO): δ (ppm) ϭ 119.9 (C-4); 121.2
(C-7); 122.5 (C-6); 125.0 (C-5); 131.7 (C-8); 148.7 (C-9); 170.0 (C-
2); 193.3 (C-11). 1H NMR ([D6]DMSO): δ (ppm) ϭ 7.21 (dd, 3J ϭ
8.6, 7.7 Hz, 1 H, 6-H); 7.35 (t, 3J ϭ 7.7 Hz, 1 H, 5-H); 7.69 (d,
N-(Benzothiazol-2-ylidene) O-Methyl Dithiocarbamate (5):[26] CH3I
(1.52 mL, 10 mmol) was added to a solution of 3-Li (2.5 g,
10 mmol) in DMF (40 mL), cooled in an ice/water bath. The mix-
ture was stirred for 2 h and poured into water. The yellow crystals
were filtered off, washed, and recrystallized from ethanol. (1.5 g,
64%), m.p. 187Ϫ188 °C. IR (cmϪ1): ν˜max ϭ 3440, 1527, 1442, 1384
1274, CϭS 1212. UV/Vis: λ (nm) ϭ 448, 340 nm. MS: m/z ϭ 240
(40) [Mϩ], 192 (100). C9H8N2S3 (244.25): calcd. C 44.97, H 3.35,
N 11.65; found C 45.19, H 3.39, N 11.70. 13C NMR ([D6]DMSO,
HETCOR, COLOC): δ (ppm) ϭ 18.7 (C-13); 115.4 (C-4); 122.9
(C-7); 124.6 (C-6); 126.9 (C-8); 127.4 (C-5); 138.3 (C-9); 165.2 (C-
2); 207.0 (C-11). 1H NMR ([D6]DMSO, HETCOR, COSY): δ
(ppm) ϭ 2.612 (s, 3 H, SCH3); 13.76 (s br, 1 H, N-H); 7.36 (dd,
3
3J ϭ 7.0, 7.9 Hz, 1 H, 5-H); 7.46 (t, J ϭ 7.9 Hz, 1 H, 6-H); 7.50
3
3J ϭ 8.6 Hz, 1 H, 7-H); 7.80 (d, J ϭ 7.7 Hz, 1 H, 4-H).
3
3
(d, J ϭ 7.0 Hz, 1 H, 4-H); 7.91 (d, J ϭ 7.9 Hz, 1 H, 7-H).
Lithium Benzothiazol-2-yldithiocarbamate (3-Li): LiOH·H2O
(0.84 g, 40 mmol) was added to a solution of 1 (3.0 g, 20 mmol) in
DMF (25 mL), and the mixture was stirred for 0.5 h and cooled in
an ice/water bath. CS2 (1.20 mL, 20 mmol) was then added, and
stirring was continued for 45 min. The mixture was poured into
CHCl3. Yellow crystals were formed, filtered off, and washed.
(3.15 g, 52%), m.p. 70 °C. IR (cmϪ1): ν˜max ϭ 1672, 1657, 1531, Cϭ
S 1211. UV/Vis: λ (nm) ϭ 422, 332. MS: m/z ϭ 236 (1) [Mϩ], 150
(100). C14H23N4S3Li (358.31): calcd. C 40.57, H 5.59, N 13.52;
found C 40.56, H 4.86, N 13.29.13C NMR ([D6]DMSO, HETCOR,
COLOC): δ (ppm) ϭ 119.6 (C-4); 121.2 (C-7); 122.6 (C-6); 125.6
(C-5); 131.1 (C-8); 148.1 (C-9); 161.8 (C-2); 213.7 (C-11). 1H NMR
([D6]DMSO, HETCOR, COSY): δ (ppm) ϭ 7.21 (dd, 3J ϭ 7.6,
S-Methyl N-(3-Methylbenzothiazol-2-ylidene) Thiocarbamate (7);
Yellow crystals were obtained from the mother liquors produced in
the reaction between 2-Na and CH3I (0.5 g, 13%), m.p. 173Ϫ174
°C. IR (cmϪ1): ν˜max ϭ 1643, 1528, 1446. UV/Vis: λ (nm) ϭ 390,
338, 279 nm. MS: m/z ϭ 238 (75) [Mϩ]. C10H11N3S2 (243.21):
calcd. C 50.39, H 4.23, N 11.75; found C 50.69, H 4.10, N 11.89.
13C NMR (CDCl3): δ (ppm) ϭ 12.6 (C-13); 30.0 (NCH3); 34.2 (C-
14); 112.1 (C-4); 122.5 (C-7); 123.7 (C-6); 124.5 (C-8); 126.9 (C-5);
136.9 (C-9); 163.7 (C-2); 177.5 (C-11). 1H NMR ([D6]DMSO): δ
(ppm) ϭ 2.32 (s, 3 H, SCH3); 3.01 (s br, 3 H, NCH3); 7.35 (s br, 1
H, 5-H); 7.51 (s br, 1 H, 6-H); 7.80 (s br, 1 H, 4-H); 7.83 (s br, 1
H, 7-H).
3
3
7.9 Hz, 1 H, 6-H); 7.35 (t, J ϭ 7.9 Hz, 1 H, 5-H); 7.69 (d, J ϭ
1-(Benzothiazol-2-yl)-3,3-dimethylthiourea (8): Aq. NH(CH3)2
(40%, 1.6 mL, 0.01 mol) was added at room temp to a solution of
5 (2.50 g, 0.01 mol) in ethanol (50 mL). The mixture was heated at
3
7.6 Hz, 1 H, 7-H); 7.84 (d, J ϭ 7.9 Hz, 1 H, 4-H).
N-(Benzothiazol-2-yl)-S,SЈ-dimethyldithiocarboimine (4): CH3I
(1.3 mL, 20 mmol) was added to a solution of 2-K (3.0 g, 10 mmol) reflux for 6 h, giving yellow pale crystals, which were filtered off,
in DMF (40 mL) in an ice/water bath. The mixture was stirred for
2 h and poured into water. The yellow solid was filtered off,
washed, and recrystallized from methanol (2.0 g, 75%), m.p. 72Ϫ73
washed, and recrystallized from methanol (1.65 g, 70%), m.p.
180Ϫ184 °C. IR (cmϪ1): ν˜max ϭ 3196, 1555, 1507, 1468, CϭS 1130.
UV/Vis: λ (nm) ϭ 386, 356 nm. MS: m/z ϭ 237 (80). C10H11N3S2
°C. IR (cmϪ1): ν˜max ϭ 1509, 1464, 1429, 1180. UV/Vis: λ (nm) ϭ (243.21): calcd. C 50.60, H 4.67, N 17.70; found C 50.17, N 4.61
380, 338 nm. MS: m/z ϭ 254 (20) [Mϩ], 192 (100). C10H10N2S3 N, 17.70. 13C NMR ([D6]DMSO): δ (ppm) ϭ 41.6 (C-14); 117.0
(258.27): calcd. C 47.24, H 3.94, N 11.02; found C 47.05, H 3.95,
(C-7); 122.7 (C-4); 123.0 (C-6); 125.9 (C-8); 126.7 (C-5); 135.8 (C-
N 11.13. 13C NMR (C6D6): δ (ppm) ϭ 121.3 (C-4); 122.8 (C-7); 9); 167.3 (C-2); 185.3 (C-11). 1H NMR ([D6]DMSO, HETCOR,
124.2 (C-6); 126.0 (C-5); 135.1 (C-8); 152.3 (C-9); 15.4 (C-13); 167.4 COSY): δ (ppm) ϭ 3.27 (s, 6 H, NCH3); 7.10 (s br, 2 H, 4-H and
Eur. J. Org. Chem. 2004, 4203Ϫ4214
www.eurjoc.org
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4211

R. Contreras et al.
FULL PAPER
7-H); 7.20 (s br, 1 H, 5-H); 7.46 (s br, 1 H, 6-H); 10.86 (s br, 1 H,
N3-H).
3J ϭ 7.9 Hz, 1 H, 4-H); 7.80 (d, J ϭ 7.9 Hz, 1 H, 7-H); 10.64 (s
3
br, 1 H, N13-H).
1-(Benzothiazol-2-ylidene)-3-methylthiourea (9): Aq. NH2CH3
(40%, 0.860 mL, 0.01 mol) was added at room temp to a solution
of 5 (2.40 g, 0.01 mol) in ethanol (40 mL). The mixture was heated
at reflux for 6 h, giving a colorless solid that was recrystallized from
1-(Benzothiazol-2-yl)-2-isopropyl-3-methylisothiourea (3): This com-
pound was obtained by treatment with isopropylamine (590 mg,
10 mmol), colorless crystals (2.3 g, 86.2%) with m.p. 52Ϫ53 °C. IR
(cmϪ1): ν˜max ϭ 1636, CϭN endo, 1652, CϭN exo; 3179, 1558, 1472,
methanol (1.80 g, 81%), m.p. 210 °C. IR (cmϪ1): ν˜max ϭ 3168, 2974, 1436. UV/Vis: λ (nm) ϭ 360, 338 nm. MS: m/z ϭ 265 (29) [M]ϩ,
1570, 1524, 1460, 1440, CϭS 1210. UV/Vis: λ (nm) ϭ 370, 338 nm.
218 (36), 176(100). C12H15N3S2 (271.24): calcd. C 54.34; H 5.66; N
MS: m/z ϭ 223 (82) [Mϩ]. C9H9N3S2 (229.19): calcd. C 48.40, H 15.85; found C 54.36; H 5.57; N 15.88. 13C NMR (CDCl3): δ
4.06, N 18.82; found C 47.71, H 4.09, N 18.82. 13C NMR (ppm) ϭ 13.5 (C-14); 23.1 (2 CH3); 23.1 (C-13); 45.9 (CH); 119.9
([D6]DMSO, HETCOR, COLOC): δ (ppm) ϭ 31.5 (C-13); 118.7
(C-7); 120.7 (C-4); 122.7 (C-6); 125.2 (C-5); 131.7 (C-8); 151.0 (C-
1
(C-4); 121.7 (C-7); 123.6 (C-6); 126.3 (C-5); 129.5 (C-8); 146.9 (C- 9); 163.8 (C-2); 171.9 (C-11). H NMR (CDCl3,): δ (ppm) ϭ 1.27
9); 161.7 (C-2); 180.4 (C-11). 1H NMR ([D6]DMSO, HETCOR, (d, J ϭ 6.6 Hz, 6 H, CH3); 2.46 (s, 3 H, SCH3); 3.85 (hept, J ϭ
3
3
COSY): δ (ppm) ϭ 3.07 (s br, 1 H, 3 H, NCH3); 7.21 (dd, 3J ϭ
6.6 Hz, 1 H, CH); 7.13 (dd, 3J ϭ 7.2, 6.6 Hz, 1 H, 6-H); 7.28 (t,
7.8, 7.9 Hz, 1 H, 6-H); 7.35 (t, 3J ϭ 7.9 Hz, 1 H, 5-H); 7.62 (d, 3J ϭ 7.2 Hz, 1 H, 5-H); 7.61 (d, J ϭ 6.6 Hz, 1 H, 7-H); 7.63 (d;
3
3J ϭ 7.9 Hz, 1 H, 4-H); 7.85 (d, 3J ϭ 7.8 Hz, 1 H, 7-H); 9.83 (s br, 3J ϭ 7.2 Hz, 1 H, 4-H); 10.70 (s br, 1 H, N13-H).
1 H, N13-H) 12.04 (s br, 1 H, N10-H).
1-(Benzothiazol-2-yl)-2,3-dimethylguanidine (14): This compound
O-Ethyl N-(Benzothiazol-2-yl) Thiocarbamate (10): Compound 4
(240 mg, 1 mmol) was dissolved in hot ethanol (30 mL) and added
to an ethanol (5 mL) solution of mercury() acetate (32 mg,
was obtained by treatment with aq. CH3NH2 (40%, 1.5 g,
20 mmol), viscous pungent yellow liquid was obtained (2.0 g, 90%).
IR (cmϪ1): ν˜max ϭ 3440, 3270, 2924, 1602, 1574, 1477, 1441. UV/
0.1 mmol). The solution was heated and stirred for 4 h. A colorless Vis: λ (nm) ϭ 396 nm. MS: m/z ϭ 220 (100), 189 (22) [Mϩ Ϫ 31].
precipitate was formed, and this was filtered off and recrystallized
C10H12N4S (228.14): calcd. C 54.54, H 5.45, N 25.45; found C
from methanol (0.15 g, 63%), m.p. 135 °C. IR (cmϪ1): ν˜max ϭ 3175, 54.80, H 5.49, N 24.24. 13C NMR (CDCl3): δ (ppm) ϭ 27.7 (C-13
1602, 1568, 1449, 1386, CϭS 1204. UV/Vis: λ (nm) ϭ 370, 285 nm.
and C-14); 118.7 (C-7); 120.7 (C-4); 121.9 (C-6); 125.3 (C-5); 131.2
1
MS: m/z ϭ 238 (44) [Mϩ]. C10H10N2OS2 (242.21): calcd. C 50.39, (C-8); 151.8 (C-9); 156.9 (C-2); 174.3 (C-11). H NMR (CDCl3): δ
H 4.23, N 11.75; found C 50.73, H 4.26, N 11.79. 13C NMR (ppm) ϭ 2.78 (s, 6 H, 2 N-CH3); 7.56 (d, J ϭ 7.6 Hz, 1 H, 4-H);
([D6]DMSO, HETCOR, COLOC): δ (ppm) ϭ 163.9 (C-2); 119.1
3
3
3
7.24 (t, J ϭ 7.6 Hz, 1 H, 5-H); 7.06 (dd, J ϭ 7.9, 7.6 Hz, 1 H, 6-
3
(C-4); 127.4 (C-5); 124.8 (C-6); 122.9 (C-7); 130.2 (C-8); 145.2 (C- H); 7.53 (d, J ϭ 7.9 Hz, 1 H, 7-H); 9.6 (s br, 2 H, N-H).
1
9); 190.6 (C-11); 67.3 (C-13); 14.8 (C-14). H NMR ([D6]DMSO,
N,NЈ-Bis(Benzothiazol-2-yl)thiourea (15): A mixture of 5 (240 mg,
HETCOR, COSY): δ (ppm) ϭ 7.65 (d, 3J ϭ 7.9 Hz, 1 H, 4-H);
1 mmol) and 1 (15 mg, 1 mmol) was heated at 160 °C for 3 h in a
7.45 (t, 3J ϭ 7.9 Hz, 1 H, 5-H); 7.33 (t, 3J ϭ 7.9 Hz, 1 H, 6-H);
glass ampoule. The yellow solid 15 was purified by recrystallization
3
7.97 (d, J ϭ 7.9 Hz, 1 H, 7-H); 13.43 (s br, 1 H, N10-H); 4.50 (q,
from CHCl3 (320 mg, 95%), m.p. 268Ϫ270 °C. IR (cmϪ1): ν˜max
ϭ
3
3J ϭ 7.0 Hz, 2 H, OCH2); 1.35 (t, J ϭ 7.0 Hz, 3 H, CH3).
3265, 1525, 1490, 1462, CϭS 1240. UV/Vis: λ (nm) ϭ 422, 358,
292 nm. MS: m/z ϭ 342 (5) [Mϩ], 308 (11) [M Ϫ H2S]ϩ, 192 (100)
[M Ϫ C7H4N2S]ϩ; 100]. C15H10N4S3 (350.27): calcd. C 52.61, H
2.94, N 16.36; found C 53.04, H 3.08, N 16.24. 13C NMR
([D6]DMSO, HETCOR, 120 °C): δ (ppm) ϭ 163.8(C-2); 118.1 (C-
O-Isopropyl N-(Benzothiazol-2-yl) Thiocarbamate (11): Compound
11 was prepared by the same procedure as for 10; colorless crystals
were obtained (20 mg, 80%), m.p. 162 °C. IR (cmϪ1): ν˜max ϭ 3466,
1601, 1572, 1441, CϭS 1202. UV/Vis: λ (nm) ϭ 384 nm. MS: m/
z ϭ 252 (30) [Mϩ]. C11H12N2OS2 (256.22): calcd. C 52.35, H 4.79, 4); 126.9 (C-5); 124.2 (C-6); 122.3 (C-7); 130.6 (C-8); 143.8 (C-9);
N 11.10; found C 51.78, H 4.77, N 11.37. 13C NMR ([D6]DMSO, 182.2 (C-11). 1H NMR ([D6]DMSO): δ (ppm) ϭ 7.29 (t, 3J ϭ
3
3
HETCOR, COLOC): δ (ppm) ϭ 21.4 (C-14); 74.3 (C-13); 118.7 7.9 Hz, 2 H, 6-H); 7.42 (t, J ϭ 7.9 Hz, 2 H, 5-H); 7.66 (d, J ϭ
3
(C-4); 122.0 (C-7); 123.9 (C-6); 126.5 (C-5); 128.4 (C-8); 144.9 (C-
7.9 Hz, 2 H, 7-H); 7.85 (d, J ϭ 7.9 Hz, 2 H, 4-H); 12.58 (s br, 2
9); 162.5 (C-2); 188.6 (C-11). 1H NMR ([D6]DMSO, HETCOR, H, N-H).
COSY): δ (ppm) ϭ 1.34 (d, 3J ϭ 7.0 Hz, 3 H, CH3) 5.51 (quint,
Sodium N,NЈ-Bis(benzothiazol-2-yl)thiourea (15-Na): Compound 15
3J ϭ 7.0 Hz, 1 H, O-CH); 7.67 (d, 3J ϭ 7.9 Hz, 1 H, 4-H); 7.32
(68 mg, 0.2 mmol) was dissolved in DMSO (0.5 mL) and heated at
110Ϫ120 °C. The solution was cooled to 25 °C, and NaH (24 mg,
1 mmol) was added. The mixture was stirred for 4 h at room temp.,
the precipitate was filtered off, and the solvent was evaporated to
afford a yellow solid (70 mg, 90%), m.p. 342Ϫ346 °C dec. IR
(cmϪ1): ν˜max ϭ 1506, 1458, 1429. UV/Vis: λ (nm) ϭ 437, 353 nm.
13C NMR ([D6]DMSO, 25 °C): δ (ppm) ϭ 117.4 (C-7); 119.3 (C-
6); 120.7 (C-4); 124.3 (C-5); 132.7 (C-8); 151.0 (C-9); 171.8 (C-2);
188.4 (C-11). 1H NMR ([D6]DMSO): δ (ppm) ϭ 6.89 (t, 3J ϭ
3
3
(dd, J ϭ 7.6, 7.9 Hz, 1 H, 6-H); 7.45 (t, J ϭ 7.9 Hz, 1 H, 5-H);
3
7.96 (d, J ϭ 7.6 Hz, 1 H, 7-H); 13.34 (s br, 1 H, N10-H).
General Procedure for Compounds 12؊14: The appropriate amine
(10 or 20 mmol, vide infra) was added to a solution of 4 (2.54 g,
10 mmol) in ethanol (10 mL), and the solution was heated at reflux
for 8 h. The solvent was evaporated at room temp.
1-(Benzothiazol-2-yl)-2,3-dimethylisothiourea (12): This compound
was obtained by treatment with aq. CH3NH2 (40%, 775 mg,
10 mmol), yellow powder (2.0 g, 90%), m.p. 61 °C. IR (cmϪ1):
ν˜max ϭ 3445, 3193, 1608, 1567, 1470, 1437. UV/Vis: λ (nm) ϭ 4022,
3
7.4 Hz, 2 H, 6-H); 7.10 (t, J ϭ 7.4 Hz, 2 H, 5-H); 7.36 (d, 3J ϭ
3
7.4 Hz, 2 H, 7-H); 7.50 (d, J ϭ 7.4 Hz, 2 H, 4-H).
360, 338 nm. MS: m/z
C10H11N3S2 (243.21): calcd. C 50.63, H 4.64, N 17.72; found C
ϭ
237.25 (29) [Mϩ], 190.25 (100). (Dibenzothiazol-2-yl)tetraazathiapentalene (16): N-Bromosuccin-
imide (89 mg, 0.5 mmol) was added at room temp. to a solution of
50.58, H 4.71, N 17.82. 13C NMR ([D6]DMSO): δ (ppm) ϭ 13.9 15 (171 mg, 0.50 mmol) in CH2Cl2 (20 mL) and stirring was main-
(C-13); 30.0 (C-14); 120.1 (C-4); 121.0 (C-7); 123.1 (C-6); 125.7 (C- tained for 2 h, water (20 mL) was added, and the reaction mixture
5); 131.4 (C-8); 151.1 (C-9); 166.0 (C-2); 171.0 (C-11). 1H NMR was extracted with CH2Cl2. The solvent was dried with MgSO4,
(CDCl3): δ (ppm) ϭ 2.32 (s, 3 H, SCH3); 2.49 (s, 3 H, NCH3); 7.21
and removed under vacuum, and the solid residue was recrys-
3
(t, 3J ϭ 7.9 Hz, 1 H, 6-H); 7.36 (t, J ϭ 7.9 Hz, 1 H, 5-H); 7.67 (d, tallized from DMSO, giving yellow crystals (60 mg, 35%), m.p.
4212
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2004, 4203Ϫ4214

A Range of Compounds Derived from 2-Aminobenzothiazole
FULL PAPER
234Ϫ238 °C. IR (cmϪ1): ν˜max ϭ 1494, 1457, 1400, 1320, 1277, 1270.
UV/Vis: λ (nm) ϭ 422, 338, 286. MS: m/z ϭ 340 (100) [Mϩ], 192
(32) [M Ϫ C7H4N2S1]ϩ, 166 (30) [M Ϫ C7H4N3S]ϩ. C15H8N4S3
(348.25): calcd. C 52.92, H 2.37, N 16.46; found C 52.77, H 2.46,
N 16.05. 13C NMR ([D6]DMSO, HETCOR, 120 °C): δ (ppm) ϭ
116.5 (C-7); 124.0 (C-4); 124.8 (C-6); 127.4 (C-5); 129.4 (C-8); 140.6
(C-9); 169.1 (C-2); 179.4 (C-11) ppm. 1H NMR ([D6]DMSO): δ
(ppm) ϭ 7.42 (d, 3J ϭ 6.5 Hz, 2 H, 7-H); 7.61 (dd, 3J ϭ 7.7, 6.5 Hz,
[1]
´
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N. Andrade-Lopez, A. Ariza-Castolo, R. Contreras, A. Vaz-
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N. Andrade-Lopez, R. Cartas-Rosado, E. Garcıa-Baez, R.
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M.-P. Fialon, N. Andrade-Lopez, N. Barba-Behrens, R. Con-
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´
´
´
´
3
3
2 H, 6-H); 8.07 (dd, J ϭ 7.7 and 6.5 Hz, 2 H, 5-H); 8.09 (d, J ϭ
6.5 Hz, 2 H, 4-H).
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N,NЈ,NЈЈ-Tris(benzothiazol-2-yl)guanidine (17): In a oil bath, 1
(354 mg, 2.36 mmol) was stirred and slowly heated at 180 °C, and
4 (300 mg, 1.18 mmol) was added. The mixture was stirred for
30 min at 180 °C, and a yellow solid was filtered off and washed
with THF to give 17 (500 mg, 90%), m.p. 274Ϫ278 °C. IR (cmϪ1):
ν˜max ϭ 3437, 1644, 1607, 1573, 1461, 1436. UV/Vis: λ (nm) ϭ 410,
283 nm. MS: m/z ϭ 458 (48) [Mϩ], 425 (1.5), 309 (100). C22H14N6S3
(470.29): calcd. C 57.62, H 3.08, N 18.33; found C 57.31, H 3.09,
N 17.89. 13C NMR ([D6]DMSO, 120 °C): δ (ppm) ϭ 165.5 (C-2);
118.5 (C-4); 126.9 (C-5); 124.0 (C-6); 122.1 (C-7); 131.3 (C-8); 151.9
(C-9); 187.4 (C-11). 1H NMR ([D6]DMSO): δ (ppm) ϭ 7.72 (d,
3J ϭ 7.9 Hz, 3 H, 4-H); 7.45 (t, 3J ϭ 7.9 Hz, 3 H, 5-H); 7.30 (t,
[6]
[7]
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N. Andrade-Lopez, Ph.D. Thesis, BQ-4464, Cinvestav-Mexico
1997.
3
3J ϭ 7.9 Hz, 3 H, 6-H); 7.87 (d, J ϭ 7.9 Hz, 3 H, 7-H); 13.23 (s
F. Bernardi, Organic Sulfur Chemistry, Elsevier 1985, pp.
br, 1 H, N-H); 13.49 (s br, 1 H, N-H).
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N,NЈ,NЈЈ-Tris(5,7-di-tert-butylbenzothiazol-2-yl)guanidine
(17a):
Compounds 4a (52 mg, 14.8 mmol) and 1a (78 mg, 29.69 mmol)
were heated in a sealed glass ampoule in an oil bath for 3 h at 165
°C, and the ampoule was then cooled in a dry ice bath and opened.
The yellow solid was washed with hexane, filtered off, and dried
under vacuum (90 mg, 77%), m.p. 304Ϫ306 °C, IR (cmϪ1): ν˜max ϭ
3436, 2962, 1643, 1579 and 1468. UV/Vis: λ (nm) ϭ 384 nm. MS:
m/z ϭ 794 (3) [Mϩ]; 533 (15), 262 (100). C46H62N6S3 (806.69):
calcd. C 69.48, H 7.79, N 10.57; found C 68.34, H 7.79, N 10.39.
13C NMR (CDCl3, Ϫ60 °C): δ (ppm) ϭ 29.9 and 36.0 (5-tBu); 31.8
and 35.2 (7-tBu) 117.0, 115.7, and 115.5 (3 C-6); 119.7, 118.9, and
118.8 (3 C-4); 127.4, 125.5, and 123.9 (3 C-8); 144.3, 143.9, and
143.8 (3 C-7); 146.0, 159.7, and 158.5 (3 C-2); 150.0, 149.4, and
149.3 (3 C-5); 150.3 151.0, and 150.9 (3 C-9); 170.5 (C-11). 1H
NMR (CDCl3, Ϫ60 °C): δ (ppm) ϭ 1.46 (s, 27 H, 7-tBu); 1.58 and
1.67 (s, 27 H, 5-tBu); 7.42 (s, 3 H, 4-H); 7.80, 7.86 and 7.97 (s, 3
H, 6-H); 13.37 (s br, 1 H, N-H); 14.08 (s br, 1 H, N-H).
S. Oae, Organic Sulfur Chemistry, Structure and Mechanism,
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N,NЈ-Di(5,7-di-tert-butylbenzothiazol-2-yl)-NЈЈЈ-(benzothiazol-2-
yl)guanidine (17b): Compounds 4 (137 mg, 0.54 mmol) and 1a
(244 mg, 0.11 mmol) were heated in a sealed glass ampoule in an
oil bath at 165 °C for 3 h. The ampoule was cooled in a dry ice
bath and opened. Compound 17b was washed with hexane, filtered
off, dried in vacuo, and obtained as a yellow solid (155 mg, 85%),
m.p. 266Ϫ268 °C. IR (cmϪ1): ν˜max ϭ 2962, 1571 and 1640. UV/
Vis: λ (nm) ϭ 383 nm. MS: m/z ϭ 682 (7.1) [Mϩ]; 533 (4.8), 262
(100). C36H46N6S3 (670.56): calcd. C 66.88, H 7.12, N 12.30; found
C 66.65, H 6.79, N 11.81. 13C NMR (CDCl3): δ (ppm) ϭ 116.1
(C-4); 126.1 (C-5); 123.8 (C-6); 121.1 (C-7); 150.8 (C-9); 119.1 (C-
4); 146.4 (C-5); 115.8 (C-6); 144.0 (C-7); 149.9 (C-9).
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J. Garın, E. Melendez, F. Merchan, P. Merino, J. Orduna, T.
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We thank Conacyt-Mexico (Grant 34714-E) for financial support
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J. Garın, E. Melendez, F. Merchan, P. Merino, J. Orduna, T.
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4214
 2004 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
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