Synthesis and biological activities of novel pyrrolo[1,2-d][1,2,4]triazin-1(2H)-one derivatives

Article abstract of DOI:10.1080/00397911.2020.1859117

A series of compounds, in which a novel 6-(4-aminophenyl)pyrrolo[1,2-d][1,2,4]triazin-1(2H)-one derivatives were synthesized and tested for their antimicrobial and antifungal activities. Among all synthesized compounds, compound 7a showed remarkable antim

Full text of DOI:10.1080/00397911.2020.1859117

Synthetic Communications
An International Journal for Rapid Communication of Synthetic Organic
Chemistry
ISSN: (Print) (Online) Journal homepage: https://www.tandfonline.com/loi/lsyc20
Synthesis and biological activities of novel
pyrrolo[1,2-d][1,2,4]triazin-1(2H)-one derivatives
Jesurajan Jebamani, Shubha Pranesh, Jayadev Shivalingappa, Manjunatha
Narayanarao & Mussuvir Pasha
To cite this article: Jesurajan Jebamani, Shubha Pranesh, Jayadev Shivalingappa, Manjunatha
Narayanarao & Mussuvir Pasha (2021) Synthesis and biological activities of novel pyrrolo[1,2-
d][1,2,4]triazin-1(2H)-one derivatives, Synthetic Communications, 51:6, 921-934, DOI:
10.1080/00397911.2020.1859117
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2021, VOL. 51, NO. 6, 921–934
https://doi.org/10.1080/00397911.2020.1859117
Synthesis and biological activities of novel
pyrrolo[1,2-d][1,2,4]triazin-1(2H)-one derivatives
Jesurajan Jebamania, Shubha Pranesha, Jayadev Shivalingappab,
Manjunatha Narayanaraoc, and Mussuvir Pashad
aDepartment of Chemistry, Don Bosco Institute of Technology, Visvesvaraya Technological University,
b
Bangalore, Karnataka, India; Department of Chemistry, SJB Institute of Technology, Bangalore,
c
Karnataka, India; East Point College of Engineering and Technology, Visvesvaraya Technological
d
University, Bangalore, India; Department of Studies and Research in Chemistry, Vijayanagara Sri
Krishnadevaraya University, Bellary, India
ABSTRACT
ARTICLE HISTORY
Received 28 July 2020
A series of compounds, in which a novel 6-(4-aminophenyl)pyr-
rolo[1,2-d][1,2,4]triazin-1(2H)-one derivatives were synthesized and
tested for their antimicrobial and antifungal activities. Among all syn-
thesized compounds, compound 7a showed remarkable antimicro-
bial activity with overall target micro-organisms and compounds 7g
and 7l displayed significant inhibitory activity against Escherichia coli
(Ec) and Scedosporium (Sc) respectively.
KEYWORDS
Acyclic/cyclic/heterocyclic
carboxylic acid;
4-aminophenyl boronic
acid; HATU; pyrrolic
acylhydrazide
GRAPHICAL ABSTRACT
Introduction
Heterocyclic compounds have been of significant interest in the modern discovery
research for the chemists and biologists due to their varied pharmacological activities.
The applications of these compounds are widely studied for the biologically active and
medicinally active molecules. The synthesis of such target molecules provides the devel-
opment of new pathways and the improvement of existing pathways in numerous disci-
plines. In the past two decades, pyrroles and its derivatives have played a vital role in
various biological activities.[1–14] Literature studies have demonstrated that there are
numerous publications for the pharmacological studies of pyrrole and 1,2,4-Triazine
pharmacophores[15–19] containing other heterocyclic systems. Many patent applications
CONTACT Shubha Pranesh
shubhapranesh@gmail.com
Department of Chemistry, Don Bosco Institute of
Technology, Visvesvaraya Technological University, Bangalore, Karnataka, India.
Supplemental data for this article can be accessed on the publisher’s website.
ß 2020 Taylor & Francis Group, LLC

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J. JEBAMANI ET AL.
Figure 1. Medicinally relevant Pyrrolo triazine derivatives.
describe the synthesis and biological activities of pyrrolotriazinone derivatives.[20–23]
The results of these studies encouraged us to synthesize and to study its pharmacology
toward target molecules. A large majority of these pharmaceutically relevant molecules
assert the presence of an amide functionality as a major pharmacophore, that signifi-
cantly involved in protein binding. Given the importance of these amide bonds in vari-
ous molecules of biological importance, they are undeniably present in an enormous
molecule of immense potential.
Pyrrolo triazines represent a class of natural and synthetic biologically active
compounds and contribute for the treatment of rheumatoid arthritis such as BMS-
582,949,[24] and a recent study on chimeric oncoproteins that contain the catalytic sub-
unit of anaplastic lymphoma kinase (ALK) and have been recognized in several clearly
defined cancers, including anaplastic large cell lymphoma (NPM-ALK), non-small cell
lung cancer (EML4-ALK), and inflammatory myofibroblastic tumors (TPM3-ALK)[25]
(Figure 1).
Recently oxo-1,2-dyhidropyrrolo[1,2-d][1,2,4]triazine-7-carboxylic acid derivatives
have been found to display a broad range of biological activities such as analgesic, anti-
inflammatory, antioxidant, antifungal, and antibacterial.[26] Hence, the importance of
the present investigation is to synthesize biologically active pharmacophores such as
1,2,4 triazine and pyrrole fused ring systems and to study their biological activities of
novel pyrrolo[1,2-d][1,2,4]triazin-6-yl)phenyl) amide derivatives that remain unabated.
Results and discussion
Chemistry
Our experimental efforts began with the synthesis of pyrrolo[1,2-d][1,2,4]triazin-1(2H)-
one 2 under the standard condition as described in the preceding literature procedure
by Lancelot et al.[27] The Pyrrolic acyl hydrazide 1 was synthesized according to the
standard procedure.[28] The reaction of 1H-pyrrole-2-carbohydrazide 1 with trimethyl
orthoformate, provided cyclized product pyrrolo[1,2-d][1,2,4]triazin-1(2H)-one 2 by fol-
lowing the reported protocol in less than 40% yield.[29] The use of lower equivalents of
trimethyl orthoformate resulted in an incomplete reaction. Similar results were observed
when the experiment was performed at 60–70 ꢀC. The reaction condition was optimized
by increasing the temperature, to 110 ꢀC in a sealed tube. To our delight, a neat conver-
sion was accomplished with >80% yield. The spectral analytical data confirmed the
structure of a desired product 2.

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Table 1. Optimization condition for preparation of 7da.
S.No
Coupling reagent
Base
Solvent
Yieldb (%)
1
2
3
4
5
6
HBTU
T3P
EDCI/HOBT
TBTU
HATU
HOAT
DIPEA
TEA
TEA
TEA
DIPEA
TEA
DMF
Toluene
DCM
DMF
DMF
38
NIL
43
12
85
37
DMF
aReaction conditions: 5(1 mmol,1equiv), 6d(1.2 mmol, 1,2equiv), coupling reagent(1.5 mmol, 1.5equiv), base(2.5 mmol,
2.5equiv), solvent(5 ml), rt, 12 h. bIsolated yields.Bold value indcates best optimized condition.
To synthesize diverse analogs based on pyrrolo[1,2,4]triazin core and to focus on the
library mode, compound 2 was selectively brominated at C-6, using bromine in CHCl3
by following the literature precedence[30] to get desired product with a 70% yield. The
1H NMR analysis indicated the presence of doublet signal at d 6.91 and 7.10 for two
protons at C-7 and C-8 position, respectively and thus confirmed the desired isomer 3.
We then focused our attention on the construction of the C–C bond on the five-
membered heterocycles. In general, boronic acid bearing electron-donating group (4)
was chosen for the Suzuki-Miyaura cross-coupling reaction for further structural
elaboration.
To begin with, the Suzuki reaction[31] of 3 with 4-aminophenyl boronic acid 4 at
80 ꢀC gave a major of the desbromo compound. However, the optimized condition
using Pd(dppf)Cl2.DCM complex and Na2CO3 as base in 1,4-dioxane at 90 ꢀC for 16 h
delivered the main scaffold, 6-(4-aminophenyl)pyrrolo[1,2-d][1,2,4]triazin-1(2H)-one 5.
The structures were unequivocally determined by NMR and LC/MS analysis.
Furthermore, to bring the scope of amide synthesis, the reaction was demonstrated by
reacting an amino group of compound 5 with aliphatic and heterocyclic carboxylic acids
6a–o to generate the analogs 7a–o. Diverse coupling reagents such as HBTU, HOAT,
T3P, TBTU, and EDCI/HOBT[32] have been employed for the feasibility study and the
results are summarized in Table 1. From the results, it is evident that HATU/
DIPEA[33a,b] in DMF at room temperature was found to be a suitable condition.
Based on the optimized conditions, we next shifted our focus on exploring the scope
of the reaction conditions for the coupling of amine 5 with different acids. All the reac-
tion yielded the coupled products in excellent yields (Scheme 1). The amide formation
with heteroaromatic acids and its derivatives 7k–o yielded around 78–80% to afford the
products in good yield. (Table 2). The synthesized derivatives were tested for their anti-
microbial and antifungal activities which are illustrated in Tables 3 and 4.
Biological activity
Antimicrobial activity
The synthesized compounds 7a–o have shown a wide range of Antimicrobial activities
toward Gram-positive bacteria such as Staphylococcus aureus (Sa), Streptococcus
faecalis(Sf), Bacillus subtilis(Bs) and Gram-negative bacteria such as Klebsiella pneumo-
nia (Kp), Escherichia coli (Ec), Pseudomonas aeruginosa (Pa) are given in Table 3.
Table 3 illustrates the efficacy of bactericide (compounds 7a–o) as measured by Agar-
disk Diffusion Method[34–36] for Gram-positive and Gram-negative bacteria. It is clearly

924
J. JEBAMANI ET AL.
Scheme 1. Synthesis of 6-(4-aminophenyl) pyrrolo[1,2-d] [1,2,4] triazin-1(2H)-one (5) and its derivatives
(7a–o).

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Table 2. Synthesis of pyrrolo[1,2-d][1,2,4]triazine phenyl amides 7a–oa.
Entry
1
Compound
7a
Structure
Yield(%)b
87
2
7b
O
82
HN
O
N
N
HN
O
O
3
4
5
7c
7d
7e
84
HN
O
N
HN
N
O
O
85
HN
N
HN
N
O
O
88
HN
N
N
HN
O
(continued)

926
J. JEBAMANI ET AL.
Table 2. Continued.
Entry
6
Compound
7f
Structure
Yield(%)b
80
O
HN
N
N
HN
O
7
7g
81
O
HN
N
N
HN
O
8
7h
81
O
HN
N
N
HN
O
9
7i
90
O
HN
N
N
HN
O
O
10
7j
89
HN
N
N
HN
O
(continued)

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927
Table 2. Continued.
Entry
11
Compound
7k
Structure
Yield(%)b
81
O
HN
N
NO2
N
H
N
N
HN
O
12
7l
79
O
HN
N
O
N
N
HN
O
13
7m
78
O
HN
N
N
N
N
HN
O
O
14
7n
81
HN
NH
N
N
HN
O
15
7o
83
O
HN
NH
O
N
H
N
N
HN
O
aReaction conditions: 5(1 mmol,1equiv), 6a-o(1.2 mmol, 1,2equiv), HATU(1.5 mmol, 1.5equiv), DIPEA(2.5 mmol, 2.5equiv),
DMF(5 ml), rt, 12 h. bIsolated yields

928
J. JEBAMANI ET AL.
Table 3. Determination of antibacterial activity by MIC for the synthesized compounds 7a–o.
Gram-positive organisms
Gram-negative organisms
The inhibitory zones of the investigated compounds (mm) (Agar-disk diffusion method)
ꢁ
Compounds
Sa
Sf
Bs
Kp
Ec
Pa
7a
7b
7c
7d
7e
7f
7g
7h
7i
7j
7k
7l
7m
7n
7o
Standard
Control
DMSO
ꢁ
16
30
24
30
16
30
30
18
16
20
18
22
18
16
14
24
0
30
18
30
18
24
16
30
16
30
18
24
22
16
24
22
23
0
16
30
14
16
24
24
18
16
20
18
30
18
22
22
16
23
0
30
16
16
30
30
16
18
24
30
30
24
18
30
24
28
25
0
30
18
22
32
16
18
40
16
16
30
18
16
30
16
28
24
0
30
16
24
22
18
24
30
16
18
14
16
30
18
18
30
23
0
Standard drug used: bacteria (Ciprofloxacin); compounds used: (40 mg in 100 lL); control: DMSO (DI-methyl sulphox-
ide). Zone of inhibition in mm. MIC in mg/mL (values in parenthesis are for MIC).
understood from the results that, larger the zone of inhibition, greater is the effective-
ness of antimicrobial chemical agents. In such a way, the synthesized compound 7h and
7n exhibited overall remarkable anti-bacterial activity toward Gram-positive bacteria
such as Staphylococcus aureus (Sa), Streptococcus faecalis (Sf), Bacillus subtilis(Bs) and
Gram-negative bacteria such as Klebsiella pneumonia (Kp), Escherichia coli (Ec), and
Pseudomonas aeruginosa (Pa). The compounds 7o and 7i are found to be more efficient
bactericidal agents toward Staphylococcus aureus (Sa) and Bacillus subtilis (Bs) respect-
ively. Interestingly, the compound 7e displays significant bactericidal activity toward
Escherichia coli (Ec) and consequently Staphylococcus aureus (Sa), Streptococcus faecalis
(Sf), and Pseudomonas aeruginosa (Pa) exhibit moderate response. The compounds 7a,
7d, and 7g reveal minimal antimicrobial activities toward all target micro-organisms.
The compounds 7o and 7k are shown considerable bactericidal efficacy toward
Klebsiella pneumoniae (Kp) and Escherichia coli (Ec).
The effect of substituents on 6-(4-aminophenyl)pyrrolo[1,2-d][1,2,4]triazin-1(2H)-one
(5) over the microorganisms were analyzed from the Table 3 and arrived the following
conclusion for the related antimicrobial activities. The presence of acyclic amides 7h
and 7n was found to exhibit enhanced bactericidal activities while the presence of CH2
linker on an amide 7a, 7d, and 7g have shown reduced efficacy. Thus compound 7h is
found to be suitable bactericide in general and may provide enhanced antimicrobial
activities while varying the substituent or the linker in our target molecule (5) for the
necessity of further studies.
The synthesized compound (7a–o) was further examined for fungicidal activities toward
Candida tenuis (Ct), Aspergillus niger(An), and Scedosporium(Sc) as listed in Table 4.
Given the studies as mentioned in Table 4, the synthesized compounds 7e, 7i, and
7m have shown considerable antifungal efficacy over the Candida tenuis (Ct),

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Table 4. Antifungal activity of synthesized compounds 7a–o.
Fungi
The inhibitory zones of the investigated compounds (mm) (Agar-disk diffusion method)
ꢁ
Compounds
Scedosporium (Sc)
Candida tenuis (Ct)
Aspergillus niger (An)
7a
7b
7c
7d
7e
7f
7g
7h
7i
7j
7k
7l
7m
7n
7o
8
30
16
2
30
8
16
16
30
16
4
30
16
4
16
30
2
8
16
4
16
16
8
4
16
30
4
8
16
4
8
4
16
30
4
8
16
16
8
30
2
30
8
16
16
8
14
Amphotericin-B
16
ꢁ
Antifungal activity at concentrations 5 mg/mL of compounds 7a–o
Aspergillus niger(An), and Scedosporium(Sc). The agent 7o exhibits remarkable fungicidal
sensitivity over Candida tenuis (Ct). The compounds 7b, 7e, 7i, and 7m have shown
reduced efficacy and become moderate resistant toward the entire fungi of our studies.
Materials and methods
Chemistry
Melting points were recorded and determined by using open capillary tubes. IR spectra
(4000–600 cmꢂ1) were recorded by JASCO FTIR-4100 Spectrophotometer by the KBr
1
pellet method. H-NMR and 13C-NMR spectra were recorded on a Bruker-400 MHz
NMR instrument and the analysis was carried with CDCl3/DMSO-d6 as a solvent.
Chemical shift values were expressed in d (ppm) relative to the reference standard tri-
methylsilane (TMS). The mass spectra for the synthesized compounds were recorded
using Shimadzu LC-2010EV with the ESI probe method. HPLC analysis was carried out
with an electron spray ionization method and a time of flight analyzer using a Waters
Micromass Q-top instrument. The progress of the reactions was monitored by TLC
using a 0.25 mm thick (Merck) plate with pre-coated silica gel 60 F254. The solvents
used for the reactions were of analytical grade and distilled once again before to use.
The starting materials and reagents were purchased from the available commercial
resources with standard specifications.
Biological assay
Test for antimicrobial and antifungal studies
Agar-disk diffusion method. The effectiveness for the antimicrobial and antifungal activ-
ities of synthesized chemical agents (7a–0) was determined by Agar-disk Diffusion
Method against the target micro-organisms such as S. aureus (Sa), S. faecalis (Sf), B.
subtilis (Bs), K.pneumoniae (Kp), E.coli (Ec), P.aeruginosa (Pa), C.tenuis (Ct), A. niger

930
J. JEBAMANI ET AL.
(An) and Scedosporium (Sc). The analysis was carried out by maintaining the standard
conditions[37] such as incubation period (24 h at 35 ꢀC for bacteria, 48–72 h at 28–30 ꢀC
for fungi), composition of the culture medium (5 mg/mL), amount of microbial cell
(109 c.f.u./mL) and antibiotics (oxacillin, and nystatin as standard). The results were
measured by the development of a zone of inhibition in mm (Resistant: <12 mm; sensi-
tive: 16–25 mm; highly sensitive: >25 mm). The experiments were recorded three times
for each analysis.
Conclusion
In summary, we have described the synthesis of novel 6-(4-aminophenyl) pyrrolo[1,2-d]
[1,2,4] triazin-1(2H)-one derivatives 7a-o. The resulted analogs were thoroughly charac-
1
terized using H NMR, and Mass spectrometer. All the compounds were screened for
antimicrobial properties. Among the tested compounds, 7h and 7n showed potent
inhibitory activity with MIC values ranging from 16 to 24 mg/mL against gram-positive
bacterium S. aureus, S. faecalis, B. subtilis and gram-negative bacterium K. pneumoniae
(Kp), E. coli (Ec), P. aeruginosa, as compared to the standard Ciprofloxacin. The MIC
values are moderate for the compounds 7c, 7e, 7f, 7k, 7i, and 7o in the range of
14–30 mg/mL. The MIC values are found to be comparatively high for the compounds
7a, 7d, and 7g. Similarly, the compounds 7a and 7c exhibited good inhibitory proper-
ties against fungi Scedosporium (Sc), Aspergillus niger (An), and Candida tenuis (Ct).
Other compounds such as 7h and 7o have exhibited significant antifungal efficacy and
the higher values were observed for 7b, 7e, 7i, and 7m. We believe that the above said
activities may be enhanced with functional group modifications. Further exploration of
the synthesized compounds for other pharmacological activities is currently in progress.
Experimental
General procedure for the preparation of N-substituted (4-(1,2-dihydro-1-
oxopyrrolo[1,2-d][1,2,4]triazin-6-yl)phenyl) derivatives
To a stirred solution of 6-(4-aminophenyl)pyrrolo[1,2-d][1,2,4]triazin-1(2H)-one 5
(0.10 g, 1 eq) in DMF(1 ml) was added 6(a–o) (1.1 eq), Diisopropylethylamine (2.5 eq)
followed by the addition of HATU (1.5 eq) at room temperature. The reaction mixture
was stirred at rt for 12 h. The completion of the reaction was monitored by LC/MS.
The reaction mixture was quenched with ice-cold water and the solidified mass was fil-
tered, washed with water, dried well to obtain the crude compound. The obtained crude
material was purified by column chromatography over silica gel (230–400 mesh) using
ethyl acetate in pet ether as eluent gradient to afford the title compounds 7(a–o).
Characterization data for selected compounds
3,3,3-Trifluoro-N-(4-(1,2-dihydro-1-oxopyrrolo[1,2-d][1,2,4]triazin-6-yl)phenyl)propa-
namide (7a)
1
Colorless solid, yield 87%, mp 234 ꢀC, H NMR (400 MHz, DMSO-d6): d ¼ 11.81 (s,
1H), 10.50 (s, 1H), 8.39 (s, 1H), 7.73 (d, J ¼ 8.00 Hz, 2H), 7.62 (d, J ¼ 12.00 Hz, 2H),

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7.12 (d, J ¼ 4.00 Hz, 1H), 6.85 (d, J ¼ 4.00 Hz, 1H), 3.55 (q, J ¼ 32.00 Hz, 2H). 13C NMR
(100 MHz, DMSO-d6): d ¼ 47.69, 114.47, 123.06, 123.15, 126.21, 128.10, 129.25, 131.06,
135.24, 137.12, 137.40, 140.27, 140.34, 141.79, 158.70, 190.13. MS (ESI) m/z: 337.3
[M þ Hþ]. Anal. Calcd for C15H11F3N4O2: C, 53.58; H, 3.30; F, 16.95; N, 16.66; O, 9.52.
Found: C, 53.93; H, 3.67; N, 16.98.
N-(4-(1,2-dihydro-1-oxopyrrolo[1,2-d][1,2,4]triazin-6-yl)phenyl)-3,3-dimethylbutana-
mide (7g)
1
Pale yellow solid, yield 81%, mp 229 ꢀC, H NMR (400 MHz, MeOD): d ¼ 8.37 (s, 1H),
7.77 (d, J ¼ 9.00 Hz, 2H), 7.53–7.59 (m, 2H), 7.23 (d, J ¼ 4.00 Hz, 1H), 6.83 (d,
J ¼ 4.00 Hz, 1H), 2.30 (s, 2H), 1.12 (s, 9H). 13C NMR (100 MHz, MeOD): d ¼ 13.72,
14.39, 17.63, 18.33, 21.72, 33.35, 37.66, 42.67, 99.32, 112.43, 115.49, 121.68, 124.56,
130.39, 133.73, 140.82, 157.67, 178.46. MS (ESI) m/z: 325.2 [M þ Hþ]. Anal. Calcd for
C18H20N4O2: C, 66.65; H, 6.21; N, 17.27; O, 9.86. Found: C, 66.92; H, 6.51; N, 17.61.
Full experimental details, spectral data of the products, 1H NMR and 13 C NMR of
all the new compounds can be found via the Supplementary Content section of this
article’s Web page
Acknowledgments
The author is grateful to the Dept of Chemistry, Don Bosco Institute of Technology, VTU for
providing the necessary facilities to carry out this research work. We are grateful to the
Department of Bio-Chemistry Don Bosco Institute of Technology for in vitro evaluation of anti-
microbial and antifungal studies.
References
ꢀ
ꢀ
ꢀ
[1] Pudziuvelyte, E.; Rıos-Luci, C.; Leon, L. G.; Cikotiene, I.; Padron, J. M. Synthesis and
Antiproliferative Activity of 2,4-Disubstituted 6-Aryl-7H-Pyrrolo[3,2-d]Pyrimidin-7-One
5-Oxides. Bioorg. Med. Chem. 2009, 17, 4955–4960. DOI: 10.1016/j.bmc.2009.05.078.
[2] Anderson, W. K.; Dean, D. C.; Endo, T. Synthesis, Chemistry, and Antineoplastic Activity
of Alpha-Halopyridinium Salts: potential Pyridone Prodrugs of Acylated Vinylogous
Carbinolamine Tumor Inhibitors. J. Med. Chem. 1990, 33, 1667–1675. DOI: 10.1021/
jm00168a021.
[3] Anderson, W. K.; Mach, R. Synthesis, Chemical Reactivity, and Antileukemic Activity of
5-Substituted 6,7-Bis(Hydroxymethyl)Pyrrolo[1,2-c]Thiazole Biscarbamates and the
Corresponding Sulfoxides and Sulfones. J. Med. Chem. 1987, 30, 2109–2115. DOI: 10.
1021/jm00394a030.
[4] Orlemans, E. O.; Verboom, W.; Scheltinga, M. W.; Reinhoudt, D. N.; Lelieveld, P.; Fiebig,
H. H.; Winterhalter, B. R.; Double, J. A.; Bibby, M. C. Synthesis, Mechanism of Action,
and Biological Evaluation of Mitosenes. J. Med. Chem. 1989, 32, 1612–1620. DOI: 10.
1021/jm00127a035.
[5] Kadushkin, A. V.; Golovko, T. V.; Kalistratov, S. G.; Sokolova, A. S. Lactam and Acid
Amide Acetals 65. Study of the Reaction of DMF Diethylacetal with 5-
Carbamoyl(Thiocarbamoyl)-6-Aminopyrrolizine Derivatives. Chem. Pharm. J. 1987, 5,
545. DOI: 10.1007/BF00474230.
[6] Anderson, W. K.; McPherson, H. L.; New, J. S.; Rick, A. C. Synthesis and Murine
Antineoplastic Activity of Bis[(Carbamoyloxy)Methyl] Derivatives of Pyrrolo[2,1-
a]Isoquinoline . J. Med. Chem. 1984, 27, 1321–1325. DOI: 10.1021/jm00376a017.

932
J. JEBAMANI ET AL.
[7] Anderson, W. K.; Heider, A. R.; Raju, N.; Yucht, J. A. Synthesis and Antileukemic
Activity of Bis[[(Carbamoyl)oxy]methyl]- Substituted Pyrrolo[2,1-a]Isoquinolines,
Pyrrolo[1,2-a]quinolines, Pyrrolo[2,1-a]isobenzazepines, and Pyrrolo[1,2-a]benzazepines.
J. Med. Chem. 1988, 31, 2097. DOI: 10.2102.1/jm00119a008.
[8] Islam, I.; Skibo, E. B.; Dorr, R. T.; Alberts, D. S. Structure-Activity Studies of Antitumor
Agents Based on Pyrrolo[1,2-a]Benzimidazoles: new Reductive Alkylating DNA Cleaving
Agents. J. Med. Chem. 1991, 34, 2954–2961. DOI: 10.1021/jm00114a003.
[9] Baraldi, P. G.; Leoni, A.; Cacciari, B.; Manfredini, S.; Simoni, D. Synthesis and Antitumor
Activity of a New Class of Pyrazolo[4,3-e]Pyrrolo[1,2-a][1,4]Diazepinone Analogs of
Pyrrolo[1,4]Benzodiazepines (PBDs). Bioorg. Med. Chem. Lett. 1993, 3, 2511–2514. DOI:
10.1016/S0960-894X(01)80707-1.
[10] Hu, W.-P.; Liang, J.-J.; Kao, C.-L.; Chen, Y.-C.; Chen, C.-Y.; Tsai, F.-Y.; Wu, M.-J.;
Chang, L.-S.; Chen, Y.-L.; Wang, J.-J. Synthesis and Antitumor Activity of Novel
Enediyne-Linked Pyrrolo[2,1-c][1,4]Benzodiazepine Hybrids. Bioorg. Med. Chem. 2009, 17,
1172–1180. DOI: 10.1016/j.bmc.2008.12.036.
[11] Malinka, W.; Redzicka, A.; Lozach, O. New Derivatives of Pyrrolo[3,4-d]Pyridazinone and
Their Anticancer Effects. Farmaco. 2004, 59, 457–462. DOI: 10.1016/j.farmac.2004.03.
002.
[12] Ghorab, M. M.; Ragab, F. A.; Heiba, H. I.; Youssef, H. A.; El-Gazzar, M. G. Synthesis of
Novel Pyrrole and Pyrrolo[2,3-d]Pyrimidine Derivatives Bearing Sulfonamide Moiety for
Evaluation as Anticancer and Radiosensitizing Agents. Bioorg. Med. Chem. Lett. 2010, 20,
6316–6320. DOI: 10.1016/j.bmcl.2010.08.005.
[13] Diana, P.; Barraja, P.; Lauria, A.; Montalbano, A.; Almerico, A. M.; Dattolo, G.;
Cirrincione, G. Pyrrolo[2,1-d][1,2,3,5]Tetrazine-4(3H)-Ones,
a
New Class of
Azolotetrazines with Potent Antitumor Activity. Eur. J. Med. Chem. 2002, 37, 267–272.
DOI: 10.1016/s0968-0896(03)00145-7.
[14] Alleca, S.; Corona, P.; Loriga, M.; Paglietti, G.; Loddo, R.; Mascia, V.; Busonera, B.; La
Colla, P. Quinoxaline Chemistry. Part 16. 4-Substituted Anilino and 4-Substituted
Phenoxymethyl Pyrrolo[1,2-a]Quinoxalines and N-[4-(Pyrrolo[1,2-a]Quinoxalin-4-
yl)Amino and Hydroxymethyl]Benzoyl Glutamates. Synthesis and Evaluation of
in Vitro Biological Activity. II Farmaco 2003, 58, 639–650. DOI: 10.1016/s0014-
827x(03)00101-0.
[15] Chen, Q.; Dai, J.; Chen, X.; Sun, M.; Sun, H.; Wang, F.; Chen, L.; Kong, L. Pyrrolo[2,1-
f][1,2,4]Triazine Derivative, and Preparation Method and Use Thereof. WO Patent
WO2015081783 A1, June 11, 2015.
[16] Dzierba, C. D.; Dasgupta, B.; Macor, J. E.; Bronson, J. J.; Rajamani, R.; Karageorge, G. N.
Pyrrolotriazine Kinase Inhibitors. WO Patent WO 2,015,054,358 A1, April 16, 2015.
[17] Lim, J.; Altman, M. D.; Baker, J.; Brubaker, J. D.; Chen, H.; Chen, Y.; Kleinschek, M. A.;
Li, C.; Liu, D.; Maclean, J. K. F.; et al. Identification of N-(1H-Pyrazol-4-yl)Carboxamide
Inhibitors of Interleukin-1 Receptor Associated Kinase 4: Bicyclic Core Modifications.
Bioorg. Med. Chem. Lett. 2015, 25, 5384–5388. DOI: 10.1016/j.bmcl.2015.09.028.
[18] Mesaros, E. F.; Angeles, T. S.; Albom, M. S.; Wagner, J. C.; Aimone, L. D.; Wan, W.; Lu,
L.; Huang, Z.; Olsen, M.; Kordwitz, E.; et al. Piperidine-3,4-Diol and Piperidine-3-ol
Derivatives of Pyrrolo[2,1-f][1,2,4]Triazine as Inhibitors of Anaplastic Lymphoma Kinase.
Bioorg. Med. Chem. Lett. 2015, 25, 1047–1052. DOI: 10.1016/j.bmcl.2015.01.019.
[19] Tyndall, E. M.; Draffan, A. G.; Frey, B.; Pool, B.; Halim, R.; Jahangiri, S.; Bond, S.; Wirth,
V.; Luttick, A.; Tilmanis, D.; et al. Prodrugs of Imidazotriazine and Pyrrolotriazine C-
Nucleosides Can Increase anti-HCV Activity and Enhance Nucleotide Triphosphate
Concentrations in Vitro. Bioorg. Med. Chem. Lett. 2015, 25, 869–873. DOI: 10.1016/j.bmcl.
2014.12.069.
[20] Su, W.-G.; Dai, G.; Xiao, K.; Jia, H.; Venable, J. D.; Bembenek, S. D. Novel Heteroaryl and
Heterocycle Compounds, Compositions and Methods. WO Patent WO2014015675 A1,
2014. Jan 30.

R
SYNTHETIC COMMUNICATIONSV
933
[21] Castro, A. C.; Chan, K.; Evans, C. A.; Janardanannair, S.; Lescarbeau, A.; Li, L.; Liu, T.;
Liu, Y.; Ren, P.; Snyder, D. A.; et al.. Heterocyclic Compounds and Uses Thereof. U.S.
Patent US 20,130,267,521 A1, October 10, 2013.
[22] Bernal Anchuela, F. J.; Carrascal Riere, M.; Caturla Javaloyes, J. F.; Gracia Ferrer, J.;
Matassa, V. G. Terricabras Belart, E. Pyrrolotiazinone Derivatives as PI3K Inhibitors.
European Patent EP2518070 A1, October 31, 2012.
[23] Carrera Carrera, F.; Perez Garcia, J. B.; Vidal Juan, B.; Sanchez Izquierdo, F.; Serra Coma,
M. C. (S)-2-(1-(6-Amino-5-Cyanopyrimidin-4-ylamino)Ethyl)-4-oxo-3-phenyl-3, 4-
Dihydropyrrolo[1,2-f][1,2,4]Triazine-5-Carbonitrile. WO Patent WO2015181052 A1,
December 3, 2015.
[24] Liu, C.; Lin, J.; Wrobleski, S. T.; Lin, S.; Hynes, J.; Wu, H.; Dyckman, A. J.; Li, T.; Wityak,
J.; Gillooly, K. M.; et al. Discovery of 4-(5-(Cyclopropylcarbamoyl)-2-
Methylphenylamino)-5-methyl-N-Propylpyrrolo[1,2-f][1,2,4]Triazine-6-Carboxamide
(BMS-582949), a Clinical p38a MAP Kinase Inhibitor for the Treatment of Inflammatory
Diseases. J. Med. Chem. 2010, 53, 6629–6639. DOI: 10.1021/jm100540x.
[25] Eugen, F. M.; Tho, V. T.; Gregory, J. W.; Craig, A. Z. Strategies to Mitigate the
Bioactivation of 2-Anilino-7-Aryl-Pyrrolo[2,1-f][1,2,4]Triazines: Identification of Orally
Bioavailable, Efficacious ALK Inhibitors. J. Med. Chem. 2012, 55, 115. DOI: 10.1021/
jm2010767.
[26] Valeriia, A.; Astakhina, A.; Maxim, V.; Olexander, K.; Vladimir, N.; Elena, K. P.; Olena, P.
Synthesis and Biological Activity of Novel Ethyl Esters of 4-R-6,8-Dimethyl-1-Oxo-1,2-
Dyhi dropyrrolo[1,2-d] [1,2,4]Triazine-7-Carboxylic Acids. J. Heterocycl. Chem. 2016, 53,
421. DOI: 10.1002/jhet.2204..
[27] Lancelot, J. C.; Maume, D.; Robba, M. Pyrrolo[1,2-d] Triazines-1,2,4. I. Pyrrolic
Derivatives. J. Heterocycl. Chem. 1980, 17, 625–629. DOI: 10.1002/jhet.5570170401.
[28] James, R. M.; Dan, A. W.; Alan, C. W.; Virgil, I. S. Synthesis of 5-Aryl-2H-Tetrazoles,
5-Aryl-2H-Tetrazole-2-Acetic
Acids,
and
[(4-Phenyl-5-Aryl-4H-1,2,4-Triazol-3-
yl)Thio]Acetic Acids as Possible Superoxide Scavengers and Antiinflammatory Agents.
J. Med. Chem. 1984, 27, 1565. DOI: 10.1021/jm00378a007..
[29] Arduengo, A. J.; Krafczyk, R.; Schmutzler, R.; Craig, H. A.; Goerlich, J. R.; Marshall, W. J.;
Unverzagt, M. Imidazolylidenes, Imidazolinylidenes and Imidazolidines. Tetrahedron.
1999, 55, 14523–14534. DOI: 10.1016/S0040-4020(99)00927-8.
[30] Gilow, M.; Edward, D. B. Bromination and Chlorination of Pyrrole and Some Reactive 1-
Substituted Pyrroles. J. Org. Chem. 1981, 46, 2221–2225. DOI: 10.1021/jo00324a005.
[31] Valerie,
G.
R.;
Ian,
S.;
Jenny,
L.
P.;
Darren,
R.
Immobilized
Tetrakis(Triphenylphosphine)Palladium(0) for Suzuki–Miyaura Coupling Reactions under
Flow Conditions. React. Chem. Eng. 2019, 4, 372. DOI: 10.1039/C8RE00235E.
[32] Joshua, R. D.; Javier, M.; Gerald, A. W. Large-Scale Applications of Amide Coupling
Reagents for the Synthesis of Pharmaceuticals. Org. Process Res. Dev. 2016, 20, 140. DOI:
10.1021/op500305s..
ꢀ
[33] (a) Andrews, D. M.; Arnould, J.-C.; Boutron, P.; Delouvrie, B.; Delvare, C.; Foote, K. M.;
Hamon, A.; Harris, C. S.; Lambert-van der Brempt, C.; Lamorlette, M.; Matusiak, Z. M.
Fischer Synthesis of Isomeric Thienopyrrole LHRH Antagonists. Tetrahedron. 2009, 65,
5805–5816. DOI: 10.1016/j.tet.2009.05.007. (b) O’Shea, P. D.; Chen, C. Y.; Gauvreau, D.;
Gosselin, F.; Hughes, G.; Nadeau, C.; Volante, R. P. A Practical Enantioselective Synthesis
of Odanacatib, a Potent Cathepsin K Inhibitor, via Triflate Displacement of an
a-Trifluoromethylbenzyl Triflate. J. Org. Chem. 2009, 74, 1605. DOI: 10.1021/jo8020314.
^
^
[34] Valgas, C.; Souza, S. M.; Smania, F. A.; Smania, A. Screening Methods to Determine
Antibacterial Activity of Natural Products. Braz. J. Microbiol. 2007, 38, 369–380. DOI: 10.
1590/S1517-83822007000200034.
[35] Wiegand, I.; Hilpert, K.; Robert, E. W. Agar and Broth Dilution Methods to Determine
the Minimal Inhibitory Concentration (MIC) of Antimicrobial Substances. Nat. Protoc.
2008, 3, 163–175. DOI: 10.1038/nprot.2007.521.

934
J. JEBAMANI ET AL.
[36] Diogo, H. C.; Melhem, M.; Sarpieri, A.; Pires, M.D. Evaluation of the Disk-Diffusion
Method to Determine the in Vitro Efficacy of Terbinafine against Subcutaneous and
Superficial Mycoses Agents. An. Bras. Dermatol. 2010, 85, 324. DOI: 10.1590/s0365-
05962010000300005.
[37] Wayne, P. A. Clinical and Laboratory Standards Institute, performance standards for anti-
microbial susceptibility testing. CLSI M2-A9, 2011, 100–121.