p-TsOH-mediated, Versatile, and Efficient Approach for the Synthesis of Triazolyl-Carbazoles from Nitrovinylcarbazoles and Azide via 1, 3-Dipolar Cycloaddition

Article abstract of DOI:10.1002/jhet.2715

An efficient method for the synthesis of N-alkylated 3-(1-benzyl-1H-1,2,3-triazole-4-yl)-9H-carbazoles (5, 6, 7, 8, 9, 10) and 9-ethyl-3,6-di(1H-1,2,3-triazole-4-yl)-9H-carbazole (13) has been developed from nitroolefines. The effects of catalyst and solvent on these reactions have been investigated. p-TsOH-THF was found to be the best system for this reaction. Various triazolyl-carbazoles were prepared in good to excellent yields.

Full text of DOI:10.1002/jhet.2715

Month 2016
p-TsOH-mediated, Versatile, and Efficient Approach for the Synthesis of
Triazolyl-Carbazoles from Nitrovinylcarbazoles and Azide via 1, 3-Dipolar
Cycloaddition
b
b
a
Vijay Kumar Reddy Avula,a,b Swetha Vallela, Jaya Shree Anireddy, and Naga Raju Chamarthi
*
aDepartment of Chemistry, Sri Venteswara University, Tiruprti 517502, Andhra Pradesh, India
bCentre for Chemical Sceince and Technology, IST, Jawaharlal Nehru Technological University Hyderabad,
Kukatpally 500085, Telangana, India
*
E-mail: rajuchamarthi10@gmail.com
Received February 11, 2016
DOI 10.1002/jhet.2715
Published online 00 Month 2016 in Wiley Online Library (wileyonlinelibrary.com).
An efficient method for the synthesis of N-alkylated 3-(1-benzyl-1H-1,2,3-triazole-4-yl)-9H-carbazoles
(5–10) and 9-ethyl-3,6-di(1H-1,2,3-triazole-4-yl)-9H-carbazole (13) has been developed from nitroolefines.
The effects of catalyst and solvent on these reactions have been investigated. p-TsOH-THF was found to be
the best system for this reaction. Various triazolyl-carbazoles were prepared in good to excellent yields.
J. Heterocyclic Chem., 00, 00 (2016).
INTRODUCTION
azides and unsaturated compounds with multi carbon–
carbon bonds (e.g., alkynes and alkenes) [18]. The Cu-
catalyzed cycloaddition from organic azides and terminal
alkynes to form 1,4-regioisomers (as sole product) of 1,2,
3-triazoles was disclosed by Tornoe and Sharp less [19].
Stimulated by these reports, other regioselective and reli-
able 1,2,3-triazole-forming processes have been explored
from azides and alkynes, especially terminal alkynes [20].
Lu et al. [21] reported the copper-catalyzed synthesis of
1H-1, 2, 3-triazoles from phenyl acetylene and sodium
azide. Barluenga et al. [22] reported the effective synthesis
of 1H-1,2,3-triazoles from (E)-β-aryl vinyl bromides and
sodium azide, catalyzed by Pd2(dba)3 and Xantphos. Zhu
and Ma [23] reported that the coupling reaction of
vinyliodides with sodium azide under CuI/L-proline
catalysis provides only vinyl azides at relatively low
temperatures. Yamamoto et al. [24] described the copper-
catalyzed synthesis of N-unsubstituted 1,2,3-triazoles from
inactivated terminal alkynes. Kuang et al. reported [25] the
copper-catalyzed synthesis of 4-aryl-1H-1,2,3-triazoles
from 1,1-dibromoalkenes and sodium azide. Yang et al.
described [26] the CuI-catalyzed synthesis of 4-aryl-1H-
1,2,3-triazoles from anti-3-aryl-2,3-dibromopropanoic acid
and sodium azide using sodium ascorbate and cesium
carbonate. Xue-Jing et al. [27], reported the synthesis of
Carbazole is an important class of indole alkaloid that
has gained much importance in recent years due to their
diverse biological activities [1–4]. The therapeutic promi-
nence of the carbazole derivatives was well established
[5,6]. Many approaches have been made for the synthesis
of heterocyclic-fused carbazoles related to natural products
[7]. Benzodihydro[a]carbazoles have been reported as
starting materials for the synthesis of various drugs and
possess important biological, pharmacological, and medic-
inal activities [8]. Apart from these, triazolyl-carbazoles
found to be as acetyl cholinesterase inhibitors [9]. Based
on these literature reports, the carbazole scaffold emerges
as an attractive building block in search of new pharmaco-
logical agents. The synthesis of substituted 1,2,3-triazoles
is of key importance due to their large biological spectrum
as antibiotic [10], antimicrobial [11], antimalarial [12],
anticancer [13], antihistaminic [14], anti-HIV [15], and an-
titubercular agents [16].
Our interest in studying 1,2,3-triazole compounds was
initiated by the recent success of Lewis base-catalyzed
nitroalkene activation [17]. One of the most important
and efficient methods for the preparation of triazole ring
system is the Huisgen cycloaddition reaction between
© 2016 Wiley Periodicals, Inc.

V. K. R.Avula, S. Vallela. J. S. Anireddy, and N. R. Chamarthi
Vol 000
4-aryl-NH-1,2,3-triazoles by 1,3-dipolar cycloaddition of
nitroolefines with NaN3. Herein, we wish to describe for
the synthesis of novel triazolylcarbazoles. Because of the
importance of the carbazole scaffolds, it emerges as an at-
tractive building block in search of new pharmacological
agents [9]. The reactivity of carbazole moiety facilitates
the reaction at room temperature (RT).
Based on the earlier observations and literature reports,
it was considered worthwhile to study the preparation of
compounds containing both the carbazole ring and triazole
ring in a single framework using efficient procedure.
Vilsmeier–Haack formylation at RT for 1 h resulted in the
formation of carbazole-3-carbaldehyde (3) [29]. This on
reaction with nitromethane under reflux conditions using
ammonium acetate as a base for 1–2 h yielded the 3-(2-
nitrovinyl)-9H-carbazole (4) [30].
In order to synthesize the target compounds, that is,
triazoles, we have taken the reference of Pereira et al [31]
where they have synthesized the triazoles by the reaction
of nitroolefines with TMSN3 using tetrabutylammonium
fluoride as a base in water and acetonitrile as a solvent
for 16h. Thus, 4 on reaction with TMSN3 using
tetrabutylammonium fluoride as a base in water and aceto-
nitrile as a solvent at RT for 24h, resulted in the formation
of triazole 5 in 55% isolated yield (Table 1). In order to im-
prove the yield, we have optimized the reaction conditions
using different acids and solvents. Results of these studies
are given in Table 1.
RESULTS AND DISCUSSION
As shown in Scheme 1, the commercially available
carbazole (1) was treated with different alkylating agents
such as methyl iodide, ethyl bromide, and butyl bromide
in acetone at RT using K2CO3 as a base to give the
corresponding N-alkylated carbazoles (2) [28]. This on
Among all the conditions used, tetrahydrofuran (THF)
was found to be the best solvent and p-TsOH as the best
acid catalyst in terms of reaction time and yield of the
product formed. Thus, we have synthesized the title
compounds using p-TsOH-THF system in good yields
(Table 2).
Scheme 1. Synthesis of 3-(2-nitrovinyl)-9H-carbazole (4).
The triazole 5 on further reaction with benzyl chloride in
dimethylformamide using K2CO3 & TBAB, resulted in the
formation of 3-(1-benzyl-1H-1,2,3-triazole-4-yl)-9H-car-
bazoles (6) (Scheme 2). Compound 6 could also be pre-
pared in another alternative method by the direct reaction
of 4 with benzyl azide in THF using p-TsOH at RT for
8–10h. Initially, the reaction of 4 with sodium azide was
carried out at RT only, but the reaction found to be very
sluggish and resulted in the lower yields. The structures
of all these compounds were confirmed by analytical and
spectral data.
Table 1
Optimization of reaction conditions.
Reaction
S. no.
Acid (equiv)
Solvent
temperature (°C)
Time (h)
Yield (%)
1
2
3
4
5
6
7
8
ZnBr2 (0.2)
AcOH (0.2)
FeCl3 (0.2)
pivOH (0.2)
TFA (0.1)
pTsOH (0.5)
pTsOH (0.6)
pTsOH (0.7)
pTsOH (0.8)
pTsOH (0.9)
pTsOH (1)
pTsOH (1)
pTsOH (1)
pTsOH (1)
pTsOH (1)
THF
THF
THF
THF
THF
THF
THF
THF
THF
THF
THF
DMF
MeCN
MeOH
H2O
RT
RT
RT
RT
RT
RT
RT
RT
RT
RT
RT
RT
RT
RT
RT
10
8
6
10
10
6
8
6
9
6
30
25
40
45
35
50
55
59
60
65
96
20
10
25
Trace
9
10
11
12
13
14
15
4
9
6
7
5
DMF, dimethylformamide; RT, room temperature; THF, tetrahydrofuran.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2016
p-TsOH-mediated: Synthesis of Triazolyl-Carbazoles from Nitrovinylcarbazoles and
Azide via 1, 3-Dipolar Cycloaddition
Table 2
p-TsOH-mediated 1, 3-dipolar cycloaddition of nitro olefines with NaN3 for synthesis of 1, 2, 3-triazoles.
Entry
1
Starting material
Product
Time (h)
Yield (%)
96
4
2
3
4.5
93
91
5
4
6
85
5
6
7
8
83
80
7
8
8
9
90
85
(Continued)
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

V. K. R.Avula, S. Vallela. J. S. Anireddy, and N. R. Chamarthi
Vol 000
Table 2
(Continued)
Entry
Entry
Starting material
Product
Time (h)
Yield (%)
9
8
80
75
72
10
11
9
10
12
8
65
Scheme 2. Synthesis of 3-(1-benzyl-1H-1, 2, 3-triazole-4-yl)-9H-carbazoles (6).
With the previous positive results, we have extended the
same work to 6-bromo-carbazole-3-carbaldehyde (7).
Compound 7 itself was prepared [29] by bromination of
3 with N-bromosuccinimide in dimethylformamide at RT
for 4–5h. Compound 7 on reaction with nitro methane
under refluxing in acetic acid using ammonium acetate as
a base for 2–3 h resulted in the formation of 6-bromo
3-(2-nitrovinyl)-9H-carbazole (8). This on reaction with
sodium azide in THF using p-TsOH at RT for 6–8h
yielded 6-bromo-3-(1H-1,2,3-triazole-4-yl)-9H-carbazole
Journal of Heterocyclic Chemistry
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Month 2016
p-TsOH-mediated: Synthesis of Triazolyl-Carbazoles from Nitrovinylcarbazoles and
Azide via 1, 3-Dipolar Cycloaddition
Scheme 3. Synthesis of 3-(1-benzyl-1H-1, 2, 3-triazole-4- yl)-6-bromo-9H-carbazoles (10).
Scheme 4. Synthesis of 9-ethyl-3, 6-di (1H-1,2,3-triazole-4-yl)-9H-carbazole (13).
(9), which on benzylation with benzyl chloride resulted in
the formation of 3-(1-benzyl-1H-1,2,3-triazole-4-yl)-6-
bromo-9H-carbazole (10) (Scheme 3). Compound 10 could
also be prepared in another alternate approach from 8 by
reacting with benzyl azide in THF and p-TsOH at RT for
8–10h.
the formation of bis-triazole, that is, 9-ethyl-3,6-di
(1H-1,2,3-triazole-4-yl)-9H-carbazole (13) (Scheme 4).
CONCLUSION
In summary, we have developed a novel and efficient
p-TsOH-mediated 1, 3-dipolar cycloaddition of nitro
olefines and inorganic NaN3 in THF for the synthesis of
valuable 1, 2, 3-triazoles. p-TsOH was discovered as a vital
catalyst in the reaction. This novel cycloaddition reaction is
a reliable method for the rapid elaboration of readily avail-
able nitro olefines and NaN3, benzyl azide into variety of 1,
2, 3-triazoles in high yields under mild conditions. The re-
action is a complementary for the well known 1, 3-dipolar
cycloaddition.
After observing the previous positive results, it was
proposed to synthesize bis-triazoles containing carbazole
moiety. The Vilsmeier–Haack formylation of 9-ethyl-9H-
carbazole (2b) was carried out at 90°C for 24 h to give
9-ethyl-9H-carbazole-3,6-dicarbaldehyde (11) [32]. 11 on
reaction with two moles of nitromethane under refluxing
conditions in acetic acid using ammonium acetate as a base
for 2 h yielded the 9-ethyl-3,6-bis (E)-2-nitrovinyl)-9H-car-
bazole (12) [33]. This on reaction with two equivalents of
sodium azide in THF at 50°C using p-TsOH resulted in
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

V. K. R.Avula, S. Vallela. J. S. Anireddy, and N. R. Chamarthi
Vol 000
EXPERIMENTAL
DMSO-d6): 29.7, 109.9, 110.3, 111.5, 111.8, 118.5,
121.8, 122.2, 123.4, 124.4, 124.9, 128.8, 140.3, 141.3:
mass spectrometry (MS) (positive mode): m/z = 249 [M
+ H]+. Anal. Calcd (%) for C15 H12N4: C, 72.56; H, 4.87;
N, 22.57. Found: C, 72.65; H, 4.82; N, 22.45.
All the commercially available starting materials,
reagents, catalyst, and solvents were used without purifica-
tion. Melting points were determined in open capillary
tubes on Guna digital melting point apparatus and are
uncorrected. Thin-layer chromatography analyses were
run on silica gel-G and visualization was performed using
9-Ethyl-3-(1H-1, 2, 3-triazole-4-yl)-9H-carbazole (5b).
Light yellow solid, Yield = (93%) m.p 185–187°C, IR
(KBr): (νmax/cm-1): 2976, 2891, 1709, 1604, 1493,
1
UV lamp or Iodine. H and 13C-NMR spectra were re-
1
1360, 1230, 1156, 1089, 939, 731; H NMR (400MHz,
corded in CDCl3 or DMSO-d6 using tetramethylslane
(TMS) as an internal standard on 400MHz and 100MHz,
respectively. Mass spectra were recorded on Agilent-
LCMS instrument. Starting materials carbazoles, nitro
methane, benzyl azide, and catalysts like p-TsOH were ob-
tained from commercial suppliers.
Preparation of 4 from 3 (general procedure) [29,30]. 9-
substituted carbazole-3-carbaldehyde (3) and 6-bromo-9-
substituted-carbazole-3-carbaldehyde (7) (10.0mmol),
nitro methane (12.0 mmol) and ammonium acetate
(6.0 mmol) were taken into a round bottom flask and was
added to 7 mL of glacial acetic acid. The resulted solution
was refluxed for 2h. Then the reaction mixture was
poured into ice-water, and the yellow solid thus formed
was collected by filtration to get crude product. The solid
residue was purified by flash column chromatography
(ethyl acetate and hexane as eluent 1:4). The desired nitro
olefine was obtained in 70% yield. Other nitroolefines
were prepared by adopting the same procedure.
Preparation of 5 from 4 (general procedure). All the
experiments were performed in round bottom flask in
fume hood and behind a blast shield. Nitro olefine
(0.3 mmol) and NaN3 (0.45 mmol) were stirred in THF
(10 mL), then, p-TsOH (0.3 mmol) was carefully added to
the mixture. The mixture was stirred at RT in air for 4h.
After completion of the reaction (detected by thin-layer
chromatography), the reaction mixture was cooled to RT,
quenched with H2O (10 mL) and extracted with EtOAc
(3 × 10mL). The organic layers were dried over
anhydrous Na2SO4 and evaporated in vacuo. The residue
was purified by flash column chromatography on silica
gel (SiO2, hexanes/EtOAc 1:3) to afford the 9-methyl-
3-(1H-1, 2, 3-triazole-4-yl)-9H-carbazole in 96% yield.
Other 1, 2, 3-triazoles were prepared by adopting the
similar procedure.
DMSO-d6/TMS): δ 1.50–1.46 (t, 3H, CH3), δ 4.44–4.38
(q, 2H, CH2), 7.26 (s, 1H, Ar-H), 7.48–7.27 (m, 3H, Ar-
H), 7.55–7.50 (m, 1H, Ar-H), 7.97–7.95 (m, 1H, Ar-H),
8.17–8.11 (t, 1H, Ar-H), 8.60 (s, 1H, Ar-H), 12.60 (s,
1H, ÀNH); 13C NMR (100MHz, DMSO-d6):14.2, 37.5,
109.8, 109.9, 118.1, 119.4, 120.9, 122.9, 124.2, 126.5,
128.8, 130.7, 139.8, 139.8, 140.4: MS (positive mode):
m/z = 263 [M +H]+. Anal. Calcd (%) for C16H14N4: C,
73.26; H, 5.38; N, 21.26. Found: C, 73.14; H, 5.46; N,
21.25.
9-Butyl-3-(1H-1, 2, 3-triazole-4-yl)-9H-carbazole (5c).
Light yellow solid, Yield = (91%) m.p 145–147°C, IR
(KBr) (νmax/cm-1): 2956, 2930, 2871, 1707, 1603, 1489,
1
1353, 1213, 1154, 971, 849, 749; H NMR (400MHz,
DMSO-d6/TMS): δ 0.88–0.86 (t, 3H, CH3), δ 1.31–1.27
(m, 2H, CH2), 1.78–1.72 (m, 2H, CH2) 4.40–4.38 (t, 2H,
CH2) 7.24–7.21 (t, 1H, Ar-H), 7.46–7.45 (t, 1H, Ar-H),
7.60–7.59 (d, 1H, Ar-H), 7.67–7.65 (d, 1H, Ar-H), 7.97–
7.972 (d, 1H, Ar-H), 8.21–8.20 (d, 1H, Ar-H), 8.33 (s,
1H, Ar-H), 8.65 (s, 1H, Ar-H), 14.56 (s, 1H, ÀNH); 13C
NMR (100 MHz, DMSO-d6): 14.1, 20.2, 31.2, 42.6,
109.9, 110.1, 118.0, 119.4, 120.9, 121.5, 122.5, 124.2,
126.5, 140.4, 140.9: MS (positive mode): m/z =291 [M
+ H]+. Anal. Calcd (%) for C18H18N4: C, 74.46; H, 6.25;
N, 19.30. Found: C, 74.31; H, 6.32; N, 19.15.
3-(1-Benzyl-1H-1,2,3-triazole-4-yl)-9-methyl-9H-carbazole
(6a). Orange color solid, Yield = (93%); m.p 126–128°C,
IR (KBr) (νmax/cm-1): 3051, 2934, 1629, 1494, 1359,
1266, 1204, 1123, 1022, 976, 808; 1H NMR (400MHz,
DMSO-d6/TMS): δ 3.33 (t, 3H, CH3), δ 5.75 (s, 2H,
PhCH2), 7.07–7.05 (d, 2H, Ar-H), 7.31–7.23 (m, 4H, Ar-
H), 7.53–7.49 (m, 2H, Ar-H), 7.62–7.60 (d, 1H, Ar-H),
7.68–7.66 (d, 1H, Ar-H), 7.98 (s, 1H, Ar-H), 8.11–8.09
(d, 1H, Ar-H), 8.23 (s, 1H, Ar-H); 13C NMR (100MHz,
DMSO-d6): 29.6, 51.6, 109.9, 110.1, 117.2, 119.7, 120.9,
121.0, 122.2, 122.7, 126.4, 126.8, 127.3, 128.2, 129.1,
133.3, 136.8, 139.1, 141.2, 141.58; MS (positive mode):
m/z = 339 [M+ H]+. Anal. Calcd (%) for C22 H18N4: C,
78.08; H, 5.36; N, 16.56. Found: C, 78.19; H, 5.31; N,
16.68.
Spectral data for title compounds
9-Methyl-3-(1H-1, 2, 3-triazole-4-yl)-9H-carbazole (5a).
Light yellow solid, Yield = (96%); m.p 244–246°C, IR
(KBr) (ν max/cm-1): 3128, 2964, 2843, 1594, 1452,
1358, 1271, 1150, 1073, 876; 1H NMR (400MHz,
DMSO-d6/TMS): δ 3.89 (s, 3H, CH3), 7.22–7.25 (t, 1H,
Ar-H), 7.47–7.50 (t, 1H, Ar-H), 7.59–7.60 (d, 1H, Ar-H),
7.65–7.67 (d, 1H, Ar-H), 7.99–8.01 (d, 1H, Ar-H), 8.19–
8.23 (t, 1H, Ar-H), 8.30 (s, 1H, Ar-H), 8.67 (s, 1H,
Ar-H), 14.88 (s, 1H, ÀNH); 13C NMR (100MHz,
3-(1-Benzyl-1H-1, 2, 3-triazole-4-yl)-9-ethyl-9H-carbazole
(6b). Orange color solid, Yield = (80%); 57–159°C, IR
(KBr) (νmax/cm-1): 3048, 2979, 1630, 1492, 1382, 1265,
1
1154, 1027, 976, 771, 733; H NMR (400MHz, DMSO-
d6/TMS): δ 1.50–1.469 (t, 3H, CH3), 4.45–4.39 (m, 2H,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2016
p-TsOH-mediated: Synthesis of Triazolyl-Carbazoles from Nitrovinylcarbazoles and
Azide via 1, 3-Dipolar Cycloaddition
1
CH2) 5.62 (s, 2H, PhCH2), 7.21–7.20 (t, 1H, Ar-H), 7.31–
7.27 (t, 1H, Ar-H), 7.38–7.35 (m, 4H, Ar-H), 7.49–7.45 (t,
2H, Ar-H), 7.56–7.53 (t, 2H, Ar-H), 7.84 (s, 1H, Ar-H),
7.98–7.96 (t, 2H, Ar-H); 13C NMR (100 MHz, DMSO-
d6): 13.8, 37.8, 51.8, 108.9, 116.4, 119.5, 120.5, 121.3,
122.4, 123.2, 126.4, 126.5, 127.3, 128.2, 128.9, 136.1,
140.2, 140.4; MS (positive mode): m/z = 353 [M + H]+.
Anal. Calcd (%) for C23 H20N4: C, 78.38; H, 5.72; N,
15.90. Found: C, 78.19; H, 5.65; N, 15.81.
3-Bromo-9-methyl-6-(1H-1, 2, 3-triazole-4-yl)-9H-carbazole
(9a). Orange color solid, Yield=(85%); m.p 206–208°C,
IR (KBr) (νmax/cm-1): 3014, 2970,1721, 1676, 1436,
1349, 1230, 1150, 1087, 962, 878,730; 1H NMR
(400 MHz, DMSO-d6/TMS): δ 3.88 (s, 3H, CH3), 7.59–
7.58 (t, 2H, Ar-H), 7.69–7.67 (d, 1H, Ar-H), 8.03–8.01
(d, 1H, Ar-H), 8.31 (s, 1H, Ar-H), 8.43 (s, 1H, Ar-H),
8.71 (s, 1H, Ar-H), 14.90 (s, 1H, ÀNH); 13C NMR
(100 MHz, DMSO-d6): 29.5, 109.8, 110.0, 118.0, 119.5,
120.9, 121.9, 122.5, 122.8, 124.2, 126.5, 130.7, 140.9,
141.5, 147.8; MS (negative mode): m/z = 325 [M-H].
Anal. Calcd (%) for C15 H11BrN4: C, 55.06; H, 3.39; N,
17.12. Found: C, 55.18; H, 3.31; N, 17.21.
3-Bromo-9-ethyl-6-(1H-1, 2, 3-triazole-4-yl)-9H-carbazole
(9b). Orange color solid, Yield= (83%); m.p 256–258°C,
IR (KBr) (νmax/cm-1): 3140, 2977, 1708, 1627, 1466,
1350, 1291, 1154, 1087, 968, 802, 732; 1H NMR
(400 MHz, DMSO-d6/TMS): δ 1.31–1.28 (t, 3H, CH3), δ
4.46–4.41 (q, 2H, CH2), 7.58 (s, 2H, Ar-H), 7.70–7.68
(d, 1H, Ar-H), 8.025–8.00 (d, 1H, Ar-H), 8.26 (s, 1H,
Ar-H), 8.46 (s, 1H, Ar-H), 8.73 (s, 1H, Ar-H), 14.89 (s,
1H, ÀNH); 13C NMR (100 MHz, DMSO-d6): 14.1, 37.7,
110.3, 111.6, 111.8, 118.7, 122.0, 123.6, 124.6, 124.9,
128.8, 130.8, 139.2, 140.3, 147.7; MS (positive mode):
m/z =341 [M+ H]+. Anal. Calcd (%) for C16 H13BrN4: C,
56.32; H, 3.84; N, 16.42. Found: C, 56.18; H, 3.79; N,
16.34.
1598, 1477, 1361, 1287, 1152, 1052, 977, 872, 733; H
NMR (400MHz, DMSO-d6/TMS): δ 3.33 (t, 3H, CH3), δ
5.75 (s, 2H, PhCH2), 7.07–7.05 (d, 2H, Ar-H), 7.31–7.23
(m, 4H, Ar-H), 7.53–7.49 (m, 2H, Ar-H), 7.62–7.60 (d,
1H, Ar-H), 7.68–7.66 (d, 1H, Ar-H), 7.98 (s, 1H, Ar-H),
8.11–8.09 (d, 1H, Ar-H), 8.23 (s, 1H, Ar-H); 13C NMR
(100 MHz, DMSO-d6): 34.4, 56.4, 114.8, 116.2, 116.7,
122.3, 126.1, 126.2, 126.5, 128.0, 128.2, 128.7, 131.7,
132.0, 132.8, 133.7, 137.8, 141.3, 143.6, 144.9, 146.2;
MS: m/z= 417 [M]. Anal. Calcd (%) for C22 H17BrN4: C,
63.32; H, 4.11; N, 13.43. Found: C, 63.21; H, 4.06; N,
13.56.
3-(1-Benzyl-1H-1, 2, 3-triazole-4-yl)-6-bromo-9-ethyl-9H-
carbazole (10b). Light orange solid, Yield = (78%); m.p
128–130°C, IR (KBr) (νmax/cm-1): 3064, 2977, 1629,
1
1599, 1476, 1380, 1266, 1088, 977, 808, 731; H NMR
(400 MHz, DMSO-d6/TMS): δ 1.48–1.45 (t, 3H, CH3),
4.40–4.38 (m, 2H, CH2) 5.62 (s, 2H, PhCH2), 7.20 (s,
2H, Ar-H), 7.46–7.29 (m, 5H, Ar-H), 7.62–7.60 (d, 2H,
Ar-H), 7.85–7.83 (d, 2H, Ar-H), 8.06 (s, 1H, Ar-H); 13C
NMR (100MHz, DMSO-d6): 13.8, 37.9, 51.9, 109.2,
100.3, 112.3, 117.4, 121.5, 122.1, 123.4, 124.1, 127.3,
128.3, 128.9, 129.2, 133.3, 136.1, 138.9, 139.0, 140.4;
MS (positive mode): m/z =433 [M + 2]+. Anal. Calcd (%)
for C23 H19BrN4: C, 64.05; H, 4.44; N, 12.99. Found: C,
64.15; H, 4.52; N, 12.85.
3-(1-Benzyl-1H-1, 2, 3-triazole-4-yl)-6-bromo-9-butyl-9H-
carbazole (10c). Light orange solid, Yield =(70%); m.p
102–104°C, IR (KBr) (νmax/cm-1): 3146, 2960, 2861,
2358, 1624, 1548, 1474, 1371, 1246, 1351,1206, 806;
1H NMR (400MHz, DMSO-d6/TMS): δ 0.99–0.98
(Broad, 3H, CH3), 1.42–1.29 (Broad, 2H, CH2), 1.87
(Broad, 2H, CH2) 4.32 (Broad, 2H, CH2) 5.62 (s, 2H,
PhCH2) 7.19 (s, 2H, Ar-H), 7.40–7.29 (m, 6H, Ar-H),
7.61–7.59 (d, 1H, Ar-H), 7.84 (s, 2H, Ar-H), 8.06 (s, 1H,
Ar-H); 13C NMR (100 MHz, DMSO-d6):13.8, 20.5, 31.1,
43.2, 51.9, 109.4, 110.6, 112.3, 117.4, 121.4, 121.9,
123.3, 124.0, 126.9, 127.3, 125.2, 128.9, 129.1, 136.1,
139.5, 140.9; MS (negative mode): m/z = 457 [M-2].
Anal. Calcd (%) for C25H23BrN4: C, 65.36; H, 5.05; N,
12.20. Found: C, 65.18; H, 5.12; N, 12.36.
3-Bromo-9-butyl-6-(1H-1, 2, 3-triazole-4-yl)-9H-carbazole
(9c). Orange color solid, Yield=(83%); m.p 162–164°C,
IR (KBr) (νmax/cm-1): 3161, 2958, 2870, 1709, 1630,
1
1463, 1357, 1218, 1151, 1056, 971, 802, 735; H NMR
(400 MHz, DMSO-d6/TMS): δ 0.88–0.86 (t, 3H, CH3), δ
1.31–1.27 (m, 2H, CH2), 1.78–1.72 (m, 2H, CH2) 4.40–
4.38 (t, 2H, CH2) 7.68–7.67 (d, 2H, Ar-H), 8.01–7.99 (d,
1H, Ar-H), 8.26 (s, 1H, Ar-H), 8.45 (s, 1H, Ar-H), 8.51
(s, 1H, Ar-H), 8.73 (s, 1H, Ar-H), 14.88 (s, 1H, ÀNH);
13C NMR (100 MHz, DMSO-d6): 14.1, 20.2, 31.1, 42.8,
110.5, 111.5, 111.9, 118.7, 121.9, 122.4, 123.5, 124.5,
124.9, 128.7, 130.7, 139.7, 140.7, 147.7; MS (negative
mode): m/z = 367 [M-H]. Anal. Calcd (%) for C18
H17BrN4: C, 58.55; H, 4.64; N, 15.17. Found: C, 58.42;
H, 4.58; N, 15.25.
4, 4′-(9-Ethyl-9H-fluorene-3, 6-diyl) bis (1H-1, 2, 3-triazole)
(13). Light yellow solid, Yield=(65%); m.p 260–262°C,
IR (KBr) (νmax/cm-1): 2975, 2892, 1702, 1605, 1494,
1
1365, 1235, 1156, 1089, 935, 732; H NMR (400MHz,
DMSO-d6/TMS): δ 1.34 (Broad, 3H, CH3), 4.46–4.48
(Broad, 2H, CH2), 7.42 (s,1H, Ar-H), 7.50–7.70 (m, 2H,
Ar-H), 7.94–8.02 (t, 2H, Ar–H), 8.15–8.31 (Broad, 1H
Ar-H), 8.62–8.76 (Broad, 2H, Ar-H), 14.90 (s, 1H, NH);
13C NMR (100 MHz, DMSO-d6): 14.2, 31.2, 110.2,
118.3, 123,0, 124.5, 130.7, 139.0, 140.3, 162.8. MS
(positive mode): m/z =330 [M +H]+. Anal. Calcd (%) for
C18H15N7; C, 65.64; H, 4.59; N, 29.77. Found: C, 65.76;
H, 4.52; N, 29.65.
3-(1-Benzyl-1H-1, 2, 3-triazole-4-yl)-6-bromo-9-methyl-9H-
carbazole (10a). Light orange solid, Yield = (80%); m.p
144–146°C, IR (KBr) (νmax/cm-1): 3055, 2943, 1675,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

V. K. R.Avula, S. Vallela. J. S. Anireddy, and N. R. Chamarthi
Vol 000
[15] Whiting, M.; Muldoon, J.; Lin, Y. C.; Silverman, M. S.;
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2011, 15, 1017.
Acknowledgments. Acknowledgements are due to UGC networking
resource center program and funding under networking scheme
and Dr. R. Nagarajan, Associate Professor, School of Chemistry,
University of Hyderabad for providing laboratory facilities.
[17] Duan, H.; Sun, X.; Liao, W.; Petersen, J. L.; Shi, X. Org Lett
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Journal of Heterocyclic Chemistry
DOI 10.1002/jhet