Syntheses of Symmetric and Unsymmetric Bis-imidazole Derivatives Using Phase-Transfer Catalysis

Article abstract of DOI:10.1002/jhet.2917

A convenient method for the preparation of symmetric and unsymmetric bisimidazole derivatives was established. The symmetric bisimidazolylmethane derivatives 1a–9a was prepared with 2-substituted imidazole derivatives 1–9 as reaction materials. However, the symmetric and unsymmetric bisimidazolylmethane derivatives 10a–12a and 10b–12b was obtained, respectively. With 4-position with the azo-groups imidazole derivatives 10–12 were used as reaction materials. All these compounds have been structurally characterized by the NMR, ESI-MS, and EA. And 8a and 12a were also characterized by the X-ray single crystal diffusion.

Full text of DOI:10.1002/jhet.2917

Month 2017
Syntheses of Symmetric and Unsymmetric Bis-imidazole Derivatives
Using Phase-Transfer Catalysis
*
Kun-Peng Zhang, Tian-Qi Jin, Jun-Qiang Zhou, Ting-Ting Ma, and Chuan-Ming Jin
Hubei Collaborative Innovation Center for Rare Metal Chemistry, Hubei Key Laboratory of Pollutant Analysis and Reuse
Technology, College of Chemistry and Chemical Engineering, Hubei Normal University, Huangshi 435002, People’s
Republic of China
*
E-mail: cmjin@email.hbnu.edu.cn; jincm2013@yahoo.com
Received February 3, 2017
DOI 10.1002/jhet.2917
Published online 00 Month 2017 in Wiley Online Library (wileyonlinelibrary.com).
A convenient method for the preparation of symmetric and unsymmetric bisimidazole derivatives was
established. The symmetric bisimidazolylmethane derivatives 1a–9a was prepared with 2-substituted
imidazole derivatives 1–9 as reaction materials. However, the symmetric and unsymmetric bisimidazoly-
lmethane derivatives 10a–12a and 10b–12b was obtained, respectively. With 4-position with the azo-
groups imidazole derivatives 10–12 were used as reaction materials. All these compounds have been
structurally characterized by the NMR, ESI-MS, and EA. And 8a and 12a were also characterized by the
X-ray single crystal diffusion.
J. Heterocyclic Chem., 00, 00 (2017).
INTRODUCTION
RESULTS AND DISCUSSION
Imidazole and polyimidazole derivatives have been
widely used in the field of coordination chemistry,
biochemistry, and pharmacological chemistry [1–3].
As a bisimidazole derivative, bisimidazolylmethane also
has a growing interest as neutral ligand and bioagent
[4,5]. The application of phase transfer catalysis (PTC)
provided a useful method for the preparation of
bisimidazolylmethane. Other bisazolylmethane compounds,
such as bistriazolylmethane, bispyrazolylmethane, and
bisbenzimidazolyl-methane, have been prepared by this
PTC method [6–8]. However, to the best of our knowledge,
bisimidazolylmethane derivatives containing different
substituted groups at 2-position or 4-position of
imidazolium rings have not been documented in the
literature by using the PTC method. Actually, those
bisimidazolylmethane derivatives containing functional
groups are a class of heterocyclic compounds which have
received a few attentions. A series of bisimidazole
derivatives have been prepared by other methods [9,10]. In
this paper, we report an efficient PTC method for the
When 2-substituted imidazole derivatives 1–9 were
reacted with dichloromethane or dibromomethane in the
presence of tetrabutylammonium bromide (TBAB), the
sole product 1a–9a was readily obtained in about
50–70% yield (Table 1). The yields were moderate except
in case of 6a. In some cases, the bisimidazolylmethane
derivatives (2a, 3a, 5a, 6a) were obtained at highly
temperature when using dibromomethane as reactant and
solvent. Because dibromomethane has higher electrophilic
reactivity and boiling point than dichloromethane.
However, the reaction between 2-(4-pyridinyl)-imidazole
and dibromomethane (entry 6) gave a lower yield than
other reactants, which is probably due to the steric effect
of the pyridinyl group located at the 2-position of
imidazole. On the other hand, the 4-pyridinyl, as an
electron-withdrawing group, can also decrease the
electron density at nitrogen atom of imidazole ring.
Compounds 7–9 bearing the azo group (―N═N―) at the
2-position of imidazole have higher yield than the
corresponding pyridinyl group compounds 4–6. The
azoyl benzene with electron-donating group (―CH3)
increased the reaction yield (entry 8, yield 74%) and
electron-withdrawing group (ꢀBr) decreased the yield
preparation
of
symmetrical
and
unsymmetrical
bisimidazolylmethane derivatives containing pyridinyl and
azophenyl-group.
© 2017 Wiley Periodicals, Inc.

K.-P. Zhang, T.-Q. Jin, J.-Q. Zhou, T.-T. Ma, and C.-M. Jin
Vol 000
Table 1
The preparation of the bisimidazolylmethane derivatives 1a–9a with the substituted groups at 2-position of imidazole ring.
Compound
R1
Solvent
Temperature (°C)
Time (h)
Yield (%)
1a
2a
3a
H
―CH3
CH2Cl2
CH2Br2
CH2Br2
25
50
40
24
24
48
66
58
52
4a
5a
CH2Cl2
CH2Br2
35
60
72
72
60
45
6a
7a
CH2Br2
CH2Cl2
60
35
72
72
30
67
8a
9a
CH2Cl2
CH2Cl2
35
40
72
72
74
47
(entry 9, yield 47%). Those results indicated that the
electronic effect of substituted group has an obvious
effect on the coupling reaction.
13CNMR spectra of 1a–9a, the peak of bridged
methylene carbon is about 52.0–53.1 ppm. It is identical
with their symmetric structure. Additionally, a single
crystal of 8a was obtained by slow evaporation of a
chloroform–methanol solution [11]. As shown in
Figure 1, there are two phenylazoimidazole moieties that
were symmetric bridged by the methenyl unit with syn-
conformation in an asymmetric unit. The benzene and
imidazole ring was connected by the azo group in anti-
conformation. And each phenylazoimidazole moiety is
almost coplanar with the dihedral angle of 4.7 and 25.2°,
respectively. Two phenylazoimidazole moieties are almost
perpendicular with their dihedral angle of 93.7°.
All compounds are solid with exception of 3a which is a
light-yellow liquid. They are insoluble in water; 1a and 2a
have better solubility in common organic solvents, for
example, CH2Cl2, CH3COCH3,CH3OH, and EtOH.
Compounds 4a–6a are insoluble in CHCl3 and CH2Cl2
and soluble in higher polarity solvent methanol and
ethanol. Conversely, compounds 7a–9a are soluble in
CHCl3 and CH2Cl2 and insoluble in methanol and
ethanol. All compounds were characterized by the NMR,
1
ESI-MS, and EA. In their HNMR spectra, 1a and 2a are
found one singlet at chemical shifts δ = 6.08 ppm,
assigned to the two hydrogen atom of bridged methylene,
indicating the symmetric structure of two imidazole rings
which have the same chemical signals at about δ = 6.79
and δ = 7.09 ppm corresponding to the hydrogen of
imidazole rings. Bridged methylene of 4a–9a has
chemical shifts downfield to δ = 6.94 ~ 7.06 ppm, due to
the deshielding effect of aryl substituted groups. In the
Under the same condition, with 4-substituted imidazole
derivatives 10–12 as started reaction materials, the
anticipative symmetric bis-imidazole derivatives 10c–12c
were not obtained. However, the other corresponding
symmetric bis-imidazole derivatives 10a–12a were
obtained (Table 2). More surprising, the unsymmetric bis-
imidazole derivatives 10b–12b were also obtained by the
chromatographic separation in lower yield. Those results
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2017
Syntheses of Symmetric and Unsymmetric Bis-imidazole Derivatives
stable than (I) due to the conjugated electronic effect of
azo group at 4-position of imidazole ring. So, the product
(10a–12a) that comes from the intermediate tautomer (II)
is major. Simultaneously, the cross-coupling product
(10b–12b) from the intermediate form (II) and (I) also
was obtained in lower yield. However, it is difficult to get
the product (10c–12c) which comes from the simultaneity
coupling of two lower probability intermediate forms (I).
Compounds 10a–12a and 10b–12b are orange–yellow
solid and soluble in CH2Cl2, CHCl3, THF, DMF, and
DMSO. In the 1HNMR spectra of the symmetric
structure, 10a–12a are found one singlet at chemical
shifts about δ = 6.98 ppm, assigned to the two hydrogen
atom of bridged methylene. The symmetric structure of
two imidazole rings and substituted groups which have a
set of the same chemical signals at about δ = 7.54 and
δ = 2.37 ppm corresponding to the hydrogen of imidazole
rings and the 2-position methyl group, respectively.
However, for the unsymmetric compounds 10b–12b,
there is one singlet at chemical shifts about
δ = 6.45 ppm, assigned to the two hydrogen atom of
bridged methylene. Compared with compounds 10a–12a,
Figure 1. The single-crystal structure of 8a. [Color figure can be viewed
at wileyonlinelibrary.com]
indicated that the tautomerism exists in the intermediate of
imidazole anion as shown in Scheme 1 in the possible
reaction mechanism. The tautomer form (II) is more
Table 2
Syntheses of the symmetric and unsymmetric bisimidazolylmethane derivatives 10–12.
Compound
R2
Solvent
CH2Cl2
Temperature (°C)
40
Time (h)
72
Yield (%)
41
10a
10b
11a
11b
12a
12b
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
CH2Cl2
40
40
40
40
40
72
72
72
72
72
20
45
18
36
21
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

K.-P. Zhang, T.-Q. Jin, J.-Q. Zhou, T.-T. Ma, and C.-M. Jin
Vol 000
Scheme 1. Tautomerism in the intermediate of imidazole anion of the
possible reaction mechanism. [Color figure can be viewed at
CONCLUSIONS
wileyonlinelibrary.com]
In summary, a convenient method for the preparation of
symmetric and unsymmetric bisimidazolylmethane
derivatives was established with the azophenyl or
pyridinyl groups at 2- or 4-position of imidazole ring.
Those results indicated that the electronic effect of
substituted group has an obvious effect on the coupling
reaction. Further work is in progress to evaluate the
influences of other substituted group on the reaction
product.
EXPERIMENTAL
All chemicals were commercially available and used as
received without further purification. The starting
materials compound 3 to 12 were prepared by the
literature method [13–15]. Melting points were
determined on a Mel-Temp melting point apparatus and
are uncorrected. 1H NMR and 13C NMR spectra were
carried out on a Bruker AMX spectrometer operating at
300 and 75 MHz, respectively. MS data were recorded on
a LCQ MAX mass spectrometer. Microanalyses were
performed on a Perkin-Elmer 2400 CHN elemental
analyzer. The FT-IR spectra were recorded from KBr
pellets in the range of 4500–400 cmꢀ1 on a Nicolet FT-
IR 6700 Excalibur series infrared spectrometer. The data
were collected at 298(2) K using a Bruker/Siemens
SMART APEX instrument (Mo Kα radiation,
λ = 0.71073 Å) using a ω–φ scan mode. Silica gel
(0.060–0.200 mm, pore diameter ~4 nm, ACROS) was
used for chromatographic separation.
there are chemical shifts downfield of 0.5 ppm, due to the
deshield effect of the unsymmetric aryl substituted
groups. The unsymmetric structure of two imidazole
rings which have two sets of chemical signals at about
δ = 7.63 ppm and δ = 6.47 ppm corresponding to the
hydrogen of imidazole rings. This is identical with their
structure in the 13CNMR spectra with the peak of bridged
methylene carbon being about 53.3 ppm. Their
symmetric structure also was confirmed by the single
crystal X-ray diffusion of 12a [12]. As shown in
Figure 2, two phenylazo groups were connected to 5-
position of two rings in the bisimidazolylmethane
moieties with anti-conformation in an asymmetric unit.
The benzene and imidazole ring was connected by the
azo group in anti-conformation. It is a little surprise that
each phenylazoimidazole moiety is not almost coplanar
with the dihedral angle of 35.6°. And two separated
benzene and imidazole rings are almost perpendicular
with each other with their dihedral angle of 86.9 and
81.3°, respectively.
Syntheses of compound: general procedure.
The 2-
substituted imidazole derivatives (4 mmol) were added to a
single-neck flask, then KOH (0.24 g, 4 mmol) and Bu4NBr
(0.1 g, 0.3 mmol) were added with two drops water. After
mixing in 15 min, 10-mL CH2Cl2 or CH2Br2 was added and
stirred at room temperature or heated for one to three days
according to different starting materials. Stopping reaction,
the solvent was removed under vacuum, and the solid
resident was subjected to flash column chromatography.
Products 1a and 2a were reported in the literature [16].
Their purification was worked by sublimation method.
Orange–yellow single crystals of 8a and 12a suitable for X-
ray analysis were obtained by the slow evaporation of the
solution of ethyl acetate and petroleum ether.
1a bis(1H-imidazol-1-yl)methane. Yield: 66%; lightless
crystal; sublimation for its purification.
1H NMR (300 MHz, CDCl3): δ = 7.78 (s, 2H), 7.13(s,
2H), 7.03 (s, 2H), 6.14(s, 2H).
13C NMR (75 MHz, CDCl3): δ = 144.6, 129.3, 116.4, 54.2.
2a bis(2-methyl-1H-imidazol-1-yl)methane. Yield: 58%;
Figure 2. The single-crystal structure of 12a. [Color figure can be viewed
lightless crystal; sublimation for its purification.
at wileyonlinelibrary.com]
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2017
Syntheses of Symmetric and Unsymmetric Bis-imidazole Derivatives
1H NMR (300 MHz, CDCl3): δ = 6.87 (s, 2H), 6.77 (s,
2H), 5.77 (s, 2H), 2.37 (s, 6H).
8a bis(2-((E)-p-tolyldiazenyl)-1H-imidazol-1-yl)methane. Yield:
74%; orange solid powder, m. p. = 208–210°C; eluent: ethyl
acetate-petroleum ether = 1:1.
13C NMR (75 MHz, CDCl3): δ = 144.8, 128.9, 119.1,
55.7, 13.7.
1H NMR (300 MHz, CDCl3): δ = 7.96 (d, J = 8.7 Hz,
4H), 7.33 (d, J = 8.7 Hz, 4H), 7.30 (s, 2H), 7.25 (s, 2H),
7.00 (s, 2H), 2.46 (s, 6H).
3a bis(2-phenyl-1H-imidazol-1-yl)methane. Yield: 52%;
light-red oil; eluent: petroleum ether-ethyl acetate = 1:4.
1H NMR (300 MHz, CDCl3): δ = 7.39–7.36 (m, 10H),
7.09(s, 2H), 6.79 (s, 2H), 6.08(s, 2H).
13C NMR (75 MHz, CDCl3): δ = 151.66, 150.89,
143.43, 131.24, 130.02, 123.40, 121.64, 52.89, 21.65.
ESI-MS: M + H+ m/z = 385.53 (calcd: 385.44).
Anal. Calcd. (%) for C21H20N8: C, 65.61; H, 5.24; N,
29.15. Found (%): C, 65.46; H, 5.36; N, 29.35.
13C NMR (75 MHz, CDCl3): δ = 143.6, 125.5, 125.3,
125.2, 124.6, 124.6, 115.2, 52.2.
ESI-MS: M + H+ m/z = 301.44 (calcd: 301.14).
Anal. Calcd. (%) for C19H16N4: C, 75.98; H, 5.37; N,
18.65. Found (%): C, 75.67; H, 5.41; N, 18.52.
9a
bis(2-((E)-p-bromophenyldiazenyl)-1H-imidazol-1-yl)
methane.
Yield: 47%; orange solid powder, m.
4a bis(2-(pyridin-2-yl)-1H-imidazol-1-yl)methane.
Yield:
p. = 222–224°C; eluent: ethyl acetate-petroleum ether = 1:2.
1H NMR (300 MHz, CDCl3): δ = 7.88 (d, J = 8.7 Hz,
4H), 7.64 (d, J = 8.7 Hz, 4H), 7.32 (d, J = 1.3 Hz, 2H),
7.27 (d, J = 1.3 Hz, 2H), 6.94 (s, 2H).
61%; light-yellow solid powder, m. p. = 152–153°C;
eluent: dichloromethane-methanol = 10:1.
1H NMR (300 MHz, CDCl3): δ = 8.55 (d, J = 7.8 Hz, 2H),
8.25(d, J = 7.6 Hz, 2H), 7.26–7.83 (m, 8H), 7.06 (s, 2H).
13C NMR (75 MHz, CDCl3): δ = 145.5, 143.3, 139.2,
132.3, 124.3, 118.3, 118.2, 117.7, 52.0.
13C NMR (75 MHz, CDCl3): δ = 151.5, 151.4, 132.7,
131.9, 127.2, 124.6, 122.1, 53.1.
ESI-MS: M + H+ m/z = 515.35 (calcd: 515.18).
Anal. Calcd. (%) for C19H14Br2N8: C, 44.38; H, 2.74; N,
21.79. Found (%): C, 44.26; H, 2.48; N, 21.97.
ESI-MS: M + H+ m/z = 302.91 (calcd: 303.33).
Anal. Calcd. (%) for C17H14N6: C, 67.54; H, 4.67; N,
27.80. Found (%): C, 67.83; H, 4.52; N, 27.63.
10a
bis[2-methyl-4-((E)-phenyldiazenyl)-1H-imidazol-1-yl]
5a bis(2-(pyridin-3-yl)-1H-imidazol-1-yl)methane.
Yield:
methane.
Yield: 41%; light-red solid powder, m.
45%; light-yellow solid powder, m. p. = 130–132°C;
eluent: ethyl acetate-methanol = 3:1.
p. = 220–222°C; eluent: ethyl acetate-petroleum ether = 5:1.
1H NMR (300 MHz, CDCl3): δ = 7.81–7.78 (m, 4H),
7.54 (s, 2H), 7.52–7.41 (m, 6H), 6.99 (s, 2H), 2.37 (s, 6H).
13C NMR (75 MHz, CDCl3): δ = 152.7, 149.0, 145.4,
131.0, 129.2, 122.3, 120.1, 50.7, 14.7.
1H NMR (300 MHz, DMSO): δ = 8.59 (s, 4H), 7.83 (d,
J = 7.8 Hz, 2H), 7.67 (s, 2H), 7.38–7.34 (m, 2H), 7.31 (s,
2H), 6.54 (s, 2H).
13C NMR (75 MHz, DMSO): δ = 150.9, 149.3, 143.9,
136.9, 127.4, 124.1, 122.7, 57.1.
ESI-MS: M + H+ m/z = 385.49 (calcd: 385.44).
Anal. Calcd. (%) for C21H20N8: C, 65.61; H, 5.24; N,
ESI-MS: M + H+ m/z = 303.22 (calcd: 303.33).
Anal. Calcd. (%) for C17H14N6: C, 67.54; H, 4.67; N,
27.80. Found (%): C, 67.72; H, 4.56; N, 27.96.
29.15. Found (%): C, 65.78; H, 5.03; N, 29.41.
10b 1-[2-methyl-4-((E)-phenyldiazenyl)-1H-imidazol-1-yl]-10-[2-
methyl-5-((E)-phenyldiazenyl)-1H-imidazol-1-yl] methane. Yield:
6a bis(2-(pyridin-4-yl)-1H-imidazol-1-yl)methane.
Yield:
20%; red solid powder, m. p. = 212–214°C; eluent: ethyl
acetate-methanol = 20:1.
30%; light-yellow solid powder, m. p. = 224–226°C;
eluent: ethyl acetate-methanol = 4:1.
1H NMR (300 MHz, CDCl3): δ = 7.87(d, J = 9.0 Hz,
2H), 7.78(d, J = 9.0 Hz, 2H), 7.60(s, 1H), 7.51(s, 1H),
7.48–7.41 (m, 6H), 6.45(s, 2H), 2.63(s, 6H).
1H NMR (300 MHz, DMSO): δ = 8.48 (d, J = 6.0 Hz,
2H), 7.40 (s, 2H), 7.34 (d, J = 6.0 Hz, 2H), 7.08 (s, 2H),
6.55 (s, 2H).
13C NMR (75 MHz, CDCl3): δ = 152.9, 152.8, 152.7,
152.6, 148.2, 147.3, 145.2, 144.5, 131.3, 130.5, 122.6,
122.4, 119.7, 118.6, 53.3, 14.0, 13.6.
13C NMR (75 MHz, DMSO): δ = 150.2, 144.5, 141.6,
137.1, 129.8, 122.8, 56.9.
ESI-MS: M + H+ m/z = 302.85 (calcd: 303.33).
Anal. Calcd. (%) for C17H14N6: C, 67.54; H, 4.67; N,
27.80. Found (%): C, 67.69; H, 4.62; N, 27.96.
ESI-MS: M + H+ m/z = 384.94 (calcd: 384.44).
Anal. Calcd. (%) for C21H20N8: C, 65.61; H, 5.24; N,
29.15. Found (%): C, 65.45; H, 5.20; N, 29.36.
11a bis[2-methyl-4-((E)-p-bromophenyldiazenyl)-1H-imidazol-
1-yl]methane. Yield: 45%; light-yellow solid powder, m.
7a
bis(2-((E)-p-phenyldiazenyl)-1H-imidazol-1-yl)
methane.
Yield: 67%; orange solid powder, m.
p. = 183–184°C; eluent: ethyl acetate-petroleum ether = 4:1.
1H NMR (300 MHz, CDCl3): δ = 8.04(d, J = 7.8 Hz, 4H),
7.55–7.48(m, 6H), 7.34 (s, 2H), 7.29 (s, 2H), 7.04 (s, 2H).
13C NMR (75 MHz, CDCl3): δ = 152.7, 151.6, 132.4,
131.5, 129.3, 123.3, 121.9, 53.0.
ESI-MS: M + H+ m/z = 357.12 (calcd: 357.38).
Anal. Calcd. (%) for C19H16N8: C, 64.03; H, 4.53; N,
31.44. Found (%): C, 64.21; H, 4.46; N, 31.65.
p. = 258–260°C(dec.); eluent: ethyl acetate-methanol = 10:1.
1H NMR (300 MHz, CDCl3): δ = 7.61 (d, J = 7.8 Hz,
8H), 7.54 (s, 2H), 6.94 (s, 2H), 2.38 (s, 6H).
13C NMR (75 MHz, CDCl3): δ = 152.7, 149.0, 145.4,
131.0, 129.2, 122.3, 120.1, 50.7, 14.7.
ESI-MS: M + H+ m/z = 543.33 (calcd: 543.23).
Anal. Calcd. (%) for C21H18Br2N8: C, 46.52; H, 3.35; N,
20.67. Found (%): C, 46.78; H, 3.52; N, 20.45.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

K.-P. Zhang, T.-Q. Jin, J.-Q. Zhou, T.-T. Ma, and C.-M. Jin
Vol 000
11b 1-[2-methyl-4-((E)-p-bromophenyldiazenyl)-1H-imidazol-
1-yl]-1-[2-methyl-5-((E)-p-bromo phenyldiazenyl)-1H-imidazol-
1-yl] methane. Yield: 18%; light-yellow solid powder, m.
Acknowledgments. This work was supported by the National
Natural Science Foundation of China (No, 21171053), the Natural
Science Foundation of Hubei Province (2015CFC799), and the
Science and Technology Foundation for Creative Research Group
of HBDE (No, T201311).
p. = 267–268°C(dec.); eluent: ethyl acetate-petroleum
ether = 2:1.
1H NMR (300 MHz, CDCl3):
δ = 7.76 (d,
J = 9.0 Hz, 2H), 7.63(s, 1H), 7.61 (d, J = 9.0 Hz,
4H), 7.59 (d, J = 9.0 Hz, 2H), 7.47 (s, 1H), 6.41 (s,
2H), 2.61(s, 6H).
REFERENCES AND NOTES
[1] Dhakshinamoorthy, A.; Garcia, H. Chem Soc Rev 2014, 43, 5750.
[2] Shima, K.; Mutoh, K.; Kobayashi, Y.; Abe, J. J Am Chem Soc
2014, 136, 3796.
[3] (a) Das, S.; Santra, S.; Mondal, P.; Majee, A.; Hajra, A.
Synthesis 2016, 48, 1269; (b) Sayed, A. R.; Gomha, S. M.; Farghaly, T.
A. J Heterocyclic Chem 2016, 53, 255.
[4] (a) Jin, C. M.; Lu, H.; Wu, L. Y.; Huang, J. Chem Comm 2006
5039; (b) Masciocchi, N.; Albisetti, A. F.; Sironi, A.; Pettinari, C.; Nicola,
C. D.; Pettinari, R. Inorg Chem 2009, 48, 5328.
[5] (a) Westrate, L.; Mackay, H.; Brown, T.; Nguyen, B.; Kluza, J.;
Wilson, W. D.; Lee, M.; Hartley, J. A. Biochemistry 2009, 48, 5679; (b)
Padalkar, V. S.; Borse, B. N.; Gupta, V. D.; Phatangare, K. R.; Patil, V.
S.; Sekar, N. J Heterocyclic Chem 2016, 53, 1347.
13C NMR (75 MHz, CDCl3): δ = 152.9, 151.5, 151.4,
148.7, 145.3, 144.4, 132.5, 132.1, 125.5, 124.8, 124.1,
123.8, 123.7, 120.2, 53.3, 14.1, 13.6.
ESI-MS: M + H+ m/z = 543.33 (calcd: 543.23).
Anal. Calcd. (%) for C21H18Br2N8: C, 46.52; H, 3.35; N,
20.67. Found (%): C, 46.37; H, 3.21; N, 20.78.
12a bis[2-methyl-4-((E)-p-tolyldiazenyl)-1H-imidazol-1-yl]
methane.
Yield: 36%; light-yellow solid powder, m.
p.
=
229–231°C; eluent: ethyl acetate-petroleum
ether = 2:1.
[6] Julia, S.; Sala, P.; Mazo, J. D.; Sancho, M.; Ochoa, C.;
Elguero, J.; Fayet, J. P.; Vertut, M. C. J Heterocycl Chem 1982, 19, 1141.
[7] Julia, S.; Mazo, J. M. D.; Avila, L. Org Prep Proc Int 1984, 16, 299.
[8] Claramunt, R. M.; Elguero, J.; Meco, T. J Heterocyclic Chem
1983, 20, 1245.
1H NMR (300 MHz, CDCl3): δ = 7.71 (d, J = 9.0 Hz,
4H), 7.50 (s, 2H), 7.29 (d, J = 9.0 Hz, 4H), 6.98 (s, 2H),
2.43 (s, 6H), 2.36 (s, 6H).
13C NMR (75 MHz, CDCl3): δ = 150.9, 148.5, 145.3,
141.8, 129.9, 122.4, 119.5, 50.7, 21.5, 14.6.
ESI-MS: M + H+ m/z = 413.54 (calcd: 413.49).
Anal. Calcd. (%) for C23H24N8: C, 66.97; H, 5.86; N,
[9] Gao, F.; Tian, X. C.; Qu, X. X.; Wang, D.; Pu, D. Synthesis
2015, 47, 65.
[10] (a) Schneider, S. K.; Schwarz, J.; Frey, G.; Herdtweck, E.;
Herrmann, W. A. J Organomet Chem 2007, 692, 4560; (b) Ramanathan,
N.; Pandurangan, G.; Kilivelu, G. J Heterocyclic Chem 2017, 54, 51.
[11] Crystal data for compound 8a: C21H20N8, M = 384.45,
Orthorhombic, a = 19.0106(18) Å, b = 10.6295(10) Å, c = 19.6066(19)
Å, V = 3962.0(7) Å3, T = 298(2) K, space group Pbca, Z = 8,
μ = 0.083 mmꢀ1, 46188 reflections measured, 3669 unique (Rint = 0.029)
which were used in all calculations, R1 = 0.0486 and wR2 = 0.1494 for
I > 2σ (I), CCDC 1507067.
[12] Crystal data for compound 12a: C23H24N8, M = 412.50,
monoclinic, a = 32.1260(5) Å, b = 5.1587(9) Å, c = 12.930(2) Å,
V = 2140.8(6) Å3, T = 298(2) K, space group C 2/c, Z = 4, μ = 0.082
mmꢀ1, 5729 reflections measured, 1477 unique (Rint = 0.074) which were
used in all calculations, R1 = 0.0577 and wR2 = 0.1535 for I > 2σ (I),
CCDC 1507069.
[13] Voss, M. E.; Beer, C. M.; Mitchell, S. A.; Blomgren, P. A.;
Zhichkin, P. E. Tetrahedron 2008, 64, 645.
[14] Senapoti, S.; Sarker, K. K.; Mondal, T. K.; Sinha, C. Transit
Metal Chem 2006, 31, 293.
[15] Byabartta, P.; Jasimuddin, S. K.; Ghosh, B. K.; Sinha, C.;
Slawin, A. M. Z.; Woollins, J. D. New J Chem 2002, 26, 1415.
[16] Jin, C. M.; Twamley, B.; Shreeve, J. M. Organometallics 2005,
24, 3020.
27.17. Found (%): C, 66.76; H, 5.97; N, 27.43.
12b 1-[2-methyl-4-((E)-p-tolyldiazenyl)-1H-imidazol-1-yl]-1-
[2-methyl-5-((E)-p-tolyldiazenyl)-1H-imidazol-1-yl] methane.
Yield:
21%;
light-yellow
solid
powder,
m.
p. = 205–207°C; eluent: ethyl acetate-metahanol = 20:1.
1H NMR (300 MHz, CDCl3): δ = 7.76 (d, J = 9.0 Hz,
2H), 7.63 (s, 1H), 7.60(d, J = 9.0 Hz, 2H), 7.58 (d,
J = 9.0 Hz, 2H), 7.54 (d, J = 9.0 Hz, 2H), 7.47 (s, 1H),
6.41 (s, 2H), 2.61 (s, 6H), 2.60 (s, 3H), 2.37 (s, 3H).
13C NMR (75 MHz, CDCl3): δ = 152.8, 150.7,
150.6, 147.8, 145.1, 144.4, 141.8, 140.9, 129.8,
129.4, 122.4, 122.2, 121.2, 119.2, 52.9, 21.4, 21.2,
13.8, 13.4.
ESI-MS: M + H+ m/z = 413.13 (calcd: 413.49).
Anal. Calcd. (%) for C23H24N8: C, 66.97; H, 5.86; N,
27.17. Found (%): C, 67.13; H, 5.96; N, 26.93.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet