Crown ethers based on bis(benzimidazol-2-yl)alkanes and 1,2-bis(benzimidazol-2-ylsulfanyl)ethane

Article abstract of DOI:10.1134/S1070363212010239

Dibenzimidazo crown ethers were synthesized by alkylation of α,ω-bis(benzimidazol-2-yl)alkanes and 1,2-bis(benzimidazol-2- ylsulfanyl)ethane with tri- and tetraethylene glycol bis(4-toluenesulfonates). The structure of 6,7,9,10,12,13,21,22-octahydro[1,14,6,9,4,11] dioxadithiadiazacyclohexadecino[4,5-a:11,10-a′]dibenzimidazole was studied by X-ray analysis

Full text of DOI:10.1134/S1070363212010239

ISSN 1070-3632, Russian Journal of General Chemistry, 2012, Vol. 82, No. 1, pp. 144–148. © Pleiades Publishing, Ltd., 2012.
Original Russian Text © Yu.E. Ivanov, D.E. Stepanov, A.A. Yavolovskii, O.V. Shishkin, V.V. D’yakonenko, G.L. Kamalov, 2012, published in Zhurnal
Obshchei Khimii, 2012, Vol. 82, No. 1, pp. 148–151.
Crown Ethers Based on Bis(benzimidazol-2-yl)alkanes
and 1,2-Bis(benzimidazol-2-ylsulfanyl)ethane
Yu. E. Ivanova, D. E. Stepanova, A. A. Yavolovskiia, O. V. Shishkinb,
V. V. D’yakonenkob, and G. L. Kamalova
a Bogatskii Physicochemical Institute, National Academy of Sciences of Ukraine,
Lyustdorfskaya doroga 86, Odessa, 65080 Ukraine
e-mail: ivanov_u@te.net.ua
b Institute of Single Crystals, National Academy of Sciences of Ukraine, Kharkov, Ukraine
Received July 20, 2010
Abstract—Dibenzimidazo crown ethers were synthesized by alkylation of α,ω-bis(benzimidazol-2-yl)alkanes
and 1,2-bis(benzimidazol-2-ylsulfanyl)ethane with tri- and tetraethylene glycol bis(4-toluenesulfonates). The
structure of 6,7,9,10,12,13,21,22-octahydro[1,14,6,9,4,11]dioxadithiadiazacyclohexadecino[4,5-a:11,10-a′]di-
benzimidazole was studied by X-ray analysis.
DOI: 10.1134/S1070363212010239
Demands in new multidentate ligands with
specified properties determine persistent attention to
the development of methods of preparation and studies
on the structure of macroheterocycles with variable
size of the ring and nature and number of donor
centers, as well as of those possessing exocyclic
coordination centers. In this connection, crown ethers
containing a benzimidazole heteroring attract some
interest. With a view to synthesize such macrocyclic
compounds we used as starting materials a series of
α,ω-bis(benzimidazol-2-yl)alkanes and 1,2-bis(benz-
imidazol-2-ylsulfanyl)ethane; their analogs are known
as efficient ligands for coordination to copper(II) ions [1].
The corresponding 15-, 16-, and 18-membered di-
benzimidazo crown ethers Ia–Ic having two or three
oxygen atoms in the macroring were synthesized by
alkylation of bis(benzimidazol-2-yl)alkanes IIa and
IIb with tri- and tetraethylene glycol bis(4-toluene-
sulfonates) in dimethylformamide (DMF) in the
presence of potassium hydroxide under argon (Scheme 1).
The yields of compounds Ia–Ic were 44–67%. Initial
1,2-bis(1H-benzimidazol-2-ylsulfanyl)ethane (IV) was
prepared by alkylation of 2,3-dihydro-1H-benz-
imidazole-2-thione (III) with 1,2-dichloroethane in
aqueous sodium hydroxide (Scheme 2).
Scheme 1.
N
N
N
N
n
N
N
KOH
DMF
n
N
H
N
H
O
O
m
IIа, IIb
Iа−Ic
+
O
O
OTs
TsO
m
n = 1, m = 1 (а); n = 1, m = 2 (b); n = 2, m = 1 (c).
144

CROWN ETHERS BASED ON BIS(BENZIMIDAZOL-2-YL)ALKANES
145
Scheme 2.
H
N
H
N
Cl
Cl
N
S
S
S
NaOH/H2O
N
H
N
N
H
IV
III
Scheme 3.
N
N
N
2
S
S
TsO
O
OTs
N
IV
NaH, DMF
O
O
V
Table 2. Bond angles in the molecule of 6,7,9,10,12,13,21,22-
octahydro[1,14,6,9,4,11]dioxadithiadiazacyclohexadecino-
[4,5-a:11,10-a′]dibenzimidazole (V)
By heating compound IV with triethylene glycol
bis(4-toluenesulfonate) and sodium hydride in boiling
DMF we succeeded in obtaining 16-membered
dibenzimidazo dithia crown V which was isolated
from the reaction mixture by column chromatography
in 11% yield (Scheme 3).
Angle
ω, deg
Angle
ω, deg
C10S1C9
C7S2C8
99.8(3)
100.2(3)
106.5(2)
128.4(2)
125.1(2)
104.0(2)
104.5(2)
1063(3)
128.1(2)
125.4(2)
113.7(2)
110.8(2)
105.4(2)
132.1(3)
122.5(3)
116.1(4)
121.8(3)
122.1(3)
117.4(4)
110.6(2)
129.3(3)
120.1(3)
113.5(2)
N2C7S2
N1C7S2
C9C8S2
C8C9S1
123.8(2)
122.7(2)
112.0(3)
113.2(2)
113.5(2)
124.6(2)
121.8(2)
120.6(2)
129.9(2)
109.5(2)
117.7(3)
121.5(3)
121.8(3)
116.4(3)
106.2(2)
131.8(2)
122.0(2)
111.9(2)
113.5(2)
109.7(2)
111.3(2)
109.5(3)
113.3(2)
C7N1C1
C7N1C22
C1N1C22
C7N2C6
C10N3C11
C10N4C16
C10N4C17
C16N4C17
C18O1C19
C20O2C21
N1C1C6
N1C1C2
C6C1C2
C3C2C1
C2C3C4
C5C4C3
C4C5C6
N2C6C1
N2C6C5
C1C6C5
N2C7N1
Table 1. Bond lengths d in the molecule of 6,7,9,10,12,13,21,22-
-octahydro[1,14,6,9,4,11]dioxadithiadiazacyclohexadecino-
[4,5-a:11,10-a′]dibenzimidazole (V)
N3C10N4
N3C10S1
N4C10S1
C12C11C16
C12C11N3
C16C11N3
C13C12C11
C12C13C14
C15C14C13
C14C15C16
N4C16C11
N4C16C15
C11C16C15
N4C17C18
O1C18C17
O1C19C20
O2C20C19
O2C21C22
N1C22C21
Bond
d, Å
Bond
d, Å
S1–C10
S1–C9
S2–C7
1.755(2)
1.822(2)
1.760(2)
1.815(3)
1.368(3)
1.373(3)
1.458(3)
1.316(3)
1.387(4)
1.312(3)
1.399(3)
1.363(3)
1.375(3)
1.460(3)
1.416(3)
1.417(3)
1.408(3)
O2–C21
C1–C6
C1–C2
C2–C3
C3–C4
C4–C5
C5–C6
C8–C9
C11–C12
C11–C16
C12–C13
C13–C14
C14–C15
C15–C16
C17–C18
C19–C20
C21–C22
1.413(3)
1.392(4)
1.400(4)
1.383(5)
1.393(6)
1.372(5)
1.405(4)
1.494(3)
1.384(3)
1.388(3)
1.375(4)
1.388(4)
1.377(4)
1.398(3)
1.514(4)
1.494(4)
1.500(4)
S2–C8
N1–C7
N1–C1
N1–C22
N2–C7
N2–C6
N3–C10
N3–C11
N4–C10
N4–C16
N4–C17
O1–C18
O1–C19
O2–C20
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 82 No. 1 2012

146
IVANOV et al.
Structure of the molecule of 6,7,9,10,12,13,21,22-octahydro[1,14,6,9,4,11]dioxadithiadiazacyclohexadecino[4,5-a:11,10-a′]dibenz-
imidazole (V) according to the X-ray diffraction data.
The newly synthesized compounds were identified
EXPERIMENTAL
1
by elemental analysis, mass spectrometry, and H
Initial α,ω-bis(1H-benzimidazol-2-yl)alkanes IIa
and IIb were synthesized according to the procedures
described in [4], 2,3-dihydro-1H-benzimidazole-2-
thione (III) was prepared as reported in [5], and tri-
and tetraethylene glycol bis(p-toluenesulfonates) were
obtained according to a procedure analogous to [6].
The solvents used in this work were purified by
standard procedures [7]. Dithio crown V was isolated
by column chromatography on neutral aluminum oxide
(50–200 μm, Merck).
NMR, and the structure of compound V was
determined by X-ray analysis (Tables 1, 2; see figure).
The macrocyclic fragment of molecule V has a chair-
like conformation. Its central part consisting of the C19,
C20, O2, C21, C2, S2, C8, C9, and S1 atoms is almost
planar; deviations of these atoms from the mean-
square plane do not exceed 0.08 Å. The C10, N4, C17,
C18, and O1 atoms deviate from the same plane by –1.54,
–2.09, –1.47, –1.92, and –1.52 Å, respectively, and the
N1 and C7 atoms, by 1.25 and 1.28 Å. The ether
fragment adopts synclinal (sc–sc–sc) conformation
with the torsion angles N4C17C18O1 –64.2(3)°,
O1C19C20O2 –73.4(3)°, and O2C21C22N1 –64.3(3)°,
whereas the thioether fragment is characterized by
antiperiplanar (ap) conformation with the torsion
angle S2C8C9S1 179.2(3)°. Such conformation of X–C–
C–X fragment (X = N, O, S) is not typical of crown
ethers which usually display alternating +sc and –sc
structures of the dioxyethylene fragments O–C–C–O
[2]. The SCH2CH2S moiety is characterized by an
appreciable steric strain, which follows from the
presence of shortened intramolecular contacts
S1···H17A 2.75 Å (sum of the van der Waals radii 3.00
Å [3]), S2···H9A 2.87, S2···H9B 2.88, S2···H22A 2.75,
and H18B···H1B 2.14 Å (2.32 Å).
The mass spectra (electron impact, 70 eV) were
recorded on an MKh-1321 mass spectrometer with
direct sample admission into the ion source heated to
1
220°C. The H NMR spectra were measured on a
Varian WXP-300 instrument at 299.95 MHz using
DMSO-d6 as solvent and tetramethylsilane as internal
reference.
Single crystals of compound V suitable for X-ray
analysis were obtained by crystallization from ethanol.
Monoclinic crystal system; C22H24N4O2S2; unit cell
parameters (21°C): a = 12.892(3), b = 4.951(2), c =
16.530 Å; β = 93.258(4)°; V = 1053.4(5) Å3; MR =
440.57; Z = 2; space group Pc; dcalc = 1.389 g/cm3; μ
(MoKα) = 0.280 mm–1; F(000) 464. The unit cell
parameters and intensities of 8277 reflections (4765
independent reflections with Rint = 0.033) were
measured on an Xcalibur-3 diffractometer (MoKα
irradiation, CCD detector, graphite monochromator, ω-
scanning, 2θmax = 60°). The structure was solved by the
direct method using SHELXTL software package [8].
The positions of hydrogen atoms were determined by
Molecules V in crystal give rise to stacks along the
[010] crystallographic axis, where the neighboring
molecules ware linked through weak hydrogen bond
C22–H22···C1′(π) (x, 1 + y, z; H···C 2.85 Å, ∠CHC
132°). In addition, shortened intermolecular contacts
S1···S2′ 3.583 Å (3.68 Å) (x, 1 + y, z) were observed
between the same molecules.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 82 No. 1 2012

CROWN ETHERS BASED ON BIS(BENZIMIDAZOL-2-YL)ALKANES
147
difference synthesis of electron density and were
refined according to the riding model (Uiso = nUeq for
non-hydrogen atom linked to a given hydrogen atom;
n = 1.2 for carbon atoms). The structure was refined
with respect to F2 by full-matrix least-squares
procedure in anisotropic approximation for nonhydro-
gen atoms; wR2 = 0.076 (4732 reflections), R1 = 0.043
[3309 reflections with F > 4σ(F)]; S = 0.968. The bond
lengths and bond angles are given in Tables 1 and 2.
The coordinates of atoms and complete sets of bond
lengths and bond angles were deposited to the
Cambridge Crystallographic Data Centre (entry no.
CCDC 768121).
imidazole (Ic) was synthesized in a similar way from
1.45 g of compound IIb and 2.29 g of triethylene
glycol bis(p-toluenesulfonate). Yield 1.35 g (67%), mp
1
260–262°C (from i-PrOH). H NMR spectrum, δ, ppm
(J, Hz): 2.09 t [4H, CH2(CH2)2CH2, J = 7], 2.98 t (4H,
CH2(CH2)2CH2, J = 7), 3.33 s (4H, OCH2CH2O), 3.67
t (4H, NCH2CH2O, J = 4.4), 4.32 t (4H, NCH2CH2O,
J = 4.4), 7.10–7.56 m (8H, Harom). Mass spectrum: m/z
404 [M]+. Found %: C 71.30; H 6.88; N 13.80.
C24H28N4O2 Calculated %: C 71.29; H 6.93; N 13.86.
1,2-Bis(benzimidazol-2-ylsulfanyl)ethane (IV).
Compound III, 1.5 g, was added to a solution of 0.4 g
of sodium hydroxide in 10 ml of water, the mixture
was stirred until dissolution, 0.5 g of 1,2-dichloro-
ethane was added, and the mixture was heated for 1 h
under reflux with stirring. After cooling, the precipitate
was filtered off through a Schott filter, washed with
water, dried at 80–100°C, and crystallized from
ethanol. Yield 0.53 g (32.5%), mp 255–257°C
7,8,15,16,18,19,21,22-Octahydro-6H-[1,4,7,13]-
dioxadiazacyclopentadecino[7,8-a:13,12-a′]dibenz-
imidazole (Ia). Compound IIa, 1.38 g, was dissolved
in 120 ml of DMF distilled over calcined CaO, 2.8 g of
potassium hydroxide was added under stirring, and the
mixture was heated for 30–40 min at 50–60°C. A solu-
tion of 2.29 g of triethylene glycol bis(p-toluene-
sulfonate) in 30 ml of DMF was added over a period of
40 min to the resulting suspension, and the mixture
was stirred for 18 h at 60–70°C under argon. The
solvent was removed on a rotary evaporator, and the
residue was washed with 100 ml of water, dried at
100–110°C, and recrystallized from isopropyl alcohol.
1
(decomp.). H NMR spectrum, δ, ppm: 3.70 s (4H,
SCH2CH2S), 7.13–7.48 m (8H, Harom), 12.76 s (2H,
NH). Mass spectrum: m/z 326 [M]+. Found, %: C
58.86; H 4.34; N 17.17. C16H14N4S2. Calculated, %:
C 58.87; H 4.33; N 17.16.
6,7,9,10,12,13,21,22-Octahydro[1,14,6,9,4,11]dioxa-
dithiadiazacyclohexadecino[4,5-a:11,10-a′]dibenz-
imidazole (V). Compound IV, 0.5 g, was dissolved in
15 ml of DMF distilled over calcined CaO, 0.075 g of
sodium hydride was added, the mixture was stirred
until it became homogeneous, 0.7 g of triethylene
glycol, bis(p-toluenesulfonate) was added, and the
mixture was stirred for 6 h at heating on a boiling
water bath. The solvent was removed, the residue was
dissolved in 20 ml of hot benzene, and the solution
was filtered. The product was isolated by column
chromatography on neutral alumina using benzene–
ethyl acetate (1:1) as eluent, followed by re-
crystallization from ethanol. Yield 0.075 g (11%), mp
145–146°C. 1H NMR spectrum, δ, ppm (J, Hz): 3.38 s
(4H, OCH2CH2O), 3.64 t (4H, NCH2CH2O, J = 5.1),
3.80 s (4H, SCH2CH2S), 4.19 t (4H, NCH2CH2O, J =
5.1), 7.10–7.45 m (8H, Harom). Mass spectrum: m/z 440
[M]+. Found, %: C 59.99; H 5.49; N 12.73.
C22H24N4O2S2. Calculated, %: C 59.98; H 5.49; N 12.72.
1
Yield 1.1 g (56%), mp 255–257°C (decomp.). H
NMR spectrum, δ, ppm (J, Hz): 2.55 quint (2H,
CH2CH2CH2, J = 6.9), 3.00 t (4H, CH2CH2CH2, J =
6.9), 3.16 s (4H, OCH2CH2O), 3.61 t (4H, NCH2·
CH2O, J = 4.35), 4.31 t (4H, NCH2CH2O, J = 4.35),
7.14–7.60 m (8H, Harom). Mass spectrum: m/z 390
[M]+. Found, %: C 70.48; H 6.64; N 14.06.
C23H26N4O2. Calculated, %: C 70.77; H 6.67; N 14.36.
7,8,15,16,18,19,21,22,24,25-Decahydro-6H-
[1,4,7,10,16]trioxadiazacyclooctadecino[10,11-a:16,15-
a′]dibenzimidazole (Ib) was synthesized in a similar
way from 1.38 g of compound IIa and 2.51 g of
tetraethylene glycol bis(p-toluenesulfonate). Yield
0.96 g (44%), mp 224–225°C (from i-PrOH). 1H NMR
spectrum, δ, ppm (J, Hz): 2.44 quint (2H,
CH2CH2CH2, J = 7.50), 3.13 t (4H, CH2CH2CH2, J =
7.50), 3.26 t (4H, OCH2CH2OCH2CH2O, J = 6.00),
3.33 t (4H, OCH2CH2OCH2CH2O, J = 6.00), 3.66 t
(4H, NCH2CH2O, J = 3.75), 4.39 t (4H, NCH2CH2O,
J = 3.75), 7.12–7.60 m (8H, Harom). Mass spectrum:
m/z 434 [M]+. Found, %: C 70.38; H 6.89; N 12.63.
C25H30N4O3 Calculated %: C 69.10; H 6.96; N 12.89.
REFERENCES
1. Craig, J.M., Clegg, W., Elsegood, M.R.G., Leese, T.A.,
Thorp, D., Thornton, P., and Lockhart, J.C., J. Chem.
Soc., Dalton Trans, 1996, no. 8, p. 1531.
6,7,8,9,16,17,19,20,22,23-Decahydro[1,4,7,14]-
dioxadiazacyclohexadecino[7,8-a:14,13-a′]dibenz-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 82 No. 1 2012

148
IVANOV et al.
2. Hiraoka, M., Crown Compounds. Their Characteristics
and Applications, Tokyo: Kodansha, 1982.
Univ., 1972, p. 114.
6. Dale, J. and Kristiansen, P.O., Acta Chem. Scand., 1972,
3. Zefirov, Yu.V. and Zorkii, P.M., Usp. Khim., 1989,
vol. 26, no. 4, p. 1471.
vol. 58, no. 5, p. 713.
7. Gordon, A.J. and Ford, R.A., The Chemist’s Companion,
New York: Wiley, 1972. Translated under the title
Sputnik khimika, Moscow: Mir, 1976, p. 437.
4. Preston, P.N., Chem. Rev., 1974, vol. 74, no. 3, p. 279.
5. Busev, A.I., Sintez novykh organicheskikh reagentov dlya
neorganicheskogo analiza (Synthesis of New Organic
Reagents for Inorganic Analysis), Moscow: Mosk. Gos.
8. Sheldrick, G.M., Acta Crystallogr., Sect. A, 2008, vol. 64,
no. 1, p. 112.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 82 No. 1 2012