Three-component, one-pot synthesis of benzo[6,7]cyclohepta[1,2-b]pyridine derivatives under catalyst free conditions and evaluation of their anti-inflammatory activity

Article abstract of DOI:10.1016/j.bmcl.2015.12.078

An efficient three-component protocol is described for the synthesis of benzo[6,7]cyclohepta[1,2-b]pyridine derivatives using β-chloroacroleins, 1,3-dicarbonyls and ammonium acetate under catalyst free conditions by using ethanol as reaction media. The mild reaction conditions, operational simplicity and high yields are the advantages of this protocol and the broad scope of this one-pot reaction makes this procedure promising for practical usages. All the final compounds were screened for anti-inflammatory activity. Among the compounds tested, the compounds 5a, 5b, 5c, 5d, 5f, and 5k exhibited significant inhibition of IL-1β and MCP-1 secretion as a measure of anti-inflammatory activity.

Full text of DOI:10.1016/j.bmcl.2015.12.078

Accepted Manuscript
Three-component, one-pot synthesis of benzo[6,7]cyclohepta[1,2-b]pyridine
derivatives under catalyst free conditions and evaluation of their anti-inflam-
matory activity
Yasodakrishna Sajja, Hanmanth Reddy Vulupala, Rajashaker Bantu, Lingaiah
Nagarapu, Sathish Babu Vasamsetti, Srigiridhar Kotamraju, Jagadeesh Babu
Nanubolu
PII:
S0960-894X(15)30391-7
DOI:
http://dx.doi.org/10.1016/j.bmcl.2015.12.078
BMCL 23439
Reference:
Bioorganic & Medicinal Chemistry Letters
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Received Date:
Revised Date:
Accepted Date:
21 October 2015
17 December 2015
22 December 2015
Please cite this article as: Sajja, Y., Vulupala, H.R., Bantu, R., Nagarapu, L., Vasamsetti, S.B., Kotamraju, S.,
Nanubolu, J.B., Three-component, one-pot synthesis of benzo[6,7]cyclohepta[1,2-b]pyridine derivatives under
catalyst free conditions and evaluation of their anti-inflammatory activity, Bioorganic & Medicinal Chemistry
Letters (2015), doi: http://dx.doi.org/10.1016/j.bmcl.2015.12.078
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Bioorganic & Medicinal Chemistry Letters
jour nal homepage: w ww.elsevier. com
Three-component, one-pot synthesis of benzo[6,7]cyclohepta[1,2-b]pyridine
derivatives under catalyst free conditions and evaluation of their anti-
inflammatory activity
Yasodakrishna Sajjaa, Hanmanth Reddy Vulupalaa, Rajashaker Bantua, Lingaiah Nagarapua*, Sathish Babu
Vasamsettib, Srigiridhar Kotamrajub, Jagadeesh Babu Nanuboluc
aOrganic Chemistry Division-II (CPC), CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad- 500007, India.
b Centre for Chemical Biology, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad-500007, India.
cCentre for X-ray Crystallography,, CSIR-Indian Institute of Chemical Technology, Tarnaka, Hyderabad-500007, India
Fax: + 91 40 27193382; Tel: +91 40 27191509; E-mail: lnagarapuiict@yahoo.com/nagarapu@iict.res.in
ARTICLE INFO
ABSTRACT
Article history:
Received
Revised
Accepted
Available online
An efficient three-component protocol is described for the synthesis of
benzo[6,7]cyclohepta[1,2-b]pyridine derivatives using β-chloroacroleins, 1,3-dicarbonyls and
ammonium acetate under catalyst free conditions by using ethanol as reaction media. The mild
reaction conditions, operational simplicity and high yields are the advantages of this protocol
and the broad scope of this one-pot reaction makes this procedure promising for practical
usages. All the final compounds were screened for anti-inflammatory activity. Among the
compounds tested, the compounds 5a, 5b, 5c, 5d, 5f, and 5k exhibited significant inhibition of
IL-1β and MCP-1secretion as a measure of anti-inflammatory activity.
Keywords:
One-pot reaction,
Ammonium acetate,
Benzosuberone,
Catalyst free conditions,
.
2009 Elsevier Ltd. All rights reserved
.
Vilsmeier Haack Arnold reaction,
Anti-inflammatory activity.
Benzocycloheptanone and its derivatives are an important
class of heterocyclic compounds, which constitute the key core of
various natural products and play a unique role in drug discovery
program. They exhibit a wide range of biological activities such
as cytotoxic, anticancer agents,1-4 as high CB1 receptors,5 and
have very potent antagonistic activity.5 In addition, these
derivatives are widely used in diverse pharmaceutical
applications, such as tricyclic antidepressants containing
dibenzosuberone moieties mostly effecting the autonomic and
central nervous systems and as traditional anti-depressants, like
amitriptyline,6 imipramine,7 and noxiptiline8 which continue to
be used as first-line drugs in treating depressive disorders (Fig1).
Pyridyl compounds are of interest to organic chemists in recent
years owing to their wide spectrum of physiological activity.9a-f
The condensed derivatives of pyridines play significant role in
desloratadine, rupatadine and lonafarnib could exhibit enhanced
biological profile with fore mentioned biological activities.
Because of the important aforementioned properties of
benzocyclohepta[1,2-b]pyridines derivatives, preparation of this
heterocyclic nucleus has gained great importance in organic
synthesis.
Due to enormous economic and ecological pressure,11
multicomponent reaction (MCR) has gained importance and has
been receiving considerable attention. Thereby MCR is becoming
an attractive strategy for the schematic construction of useful
novel and complex chemical compounds. The process efficiency
concept is not only related to high chemical yield, but also to
minimize the use of large amounts of harmful organic reagents,
solvents, catalyst, and undesired chemical waste.12 Developing a
new MCR from easily available, effortless, and uncomplicated
substrates is one of the most predominant research topics in
organic chemistry. This novel schematic approach affords
multiple molecules in a one-pot reaction and advances in a highly
efficient and atom-economical manner to generate multiple and
diverse new bonds, which saves time and energy by eluding
multistep purifications of various intermediates.13 Our recent
studies have been focusing on the development of new synthetic
bioactive
molecules,
especially
in
the
form
of
benzo[5,6]cyclohepta[1,2-b]pyridines which are structural
analogues to benzosuberone. The benzo[5,6]cyclohepta[1,2-
b]pyridine is an important core biologically active compound
with diverse biological activities, such as antihistamine as well as
antitumor and anti-inflammatory activities.10a-j It is a highly
potent pharmacophore and widely used in drugmolecular design.
Derivatives containing this group such as loratadine,

pathways for the preparation of cycle compounds, which was
based on the use of cascade or one-pot reactions.14
The reaction was performed with β-chloroacroleins (2) [0.42 mmol], 1,3-
dicarbonyls (3) [0.42 mmol] and ammonium acetate (4) [0.84 mmol] in
ethanol at reflux for 8 h.Yields are given after column chromatography.
Scheme 1: Synthesis of benzo[6,7]cyclohepta[1,2-b]pyridine
derivatives.
The key intermediate (Z)-9-chloro-6,7-dihydro-5H-
benzo[7]annulene-8-carbaldehyde (2a-b) was synthesized using
Vilsmeier Haack Arnold reaction18 of substituted benzosuberones
(1a-b) by treating with POCl3, dimethylformamide in 84-87%
yield. The structures of all the synthesized compounds were
confirmed by spectral data (1H NMR, 13C NMR, FTIR and ESI-
MS). In the 1H NMR spectra, the presence of characteristic
singlet at δ 10.33 ppm representing one proton provided evidence
for the formation of carbaldehyde 2b. The required starting
compounds were synthesized from Fridel-Craft’s acylation of
aromatic hydrocarbons with glutaric anhydride furnishing aryl
butyric acids which on Clemmenson reduction followed by
cyclization with excess polyphosphoric acid gave substituted
benzosuberones 2a-b (Scheme 2).
Figure 1: Representative examples of biologically active
benzosuberones.
In a recent articles Jagath Reddy et al.15 and Thoraya et
al.16 found that, β-enaminone are key intermediate for the
synthesis of these substituted pyridines by using acetic acid and
Mont-morillonite K10 in 2-propanol and our literature survey
revealed that the synthesis of these pyridines was not achieved
using β-chloroacroleins and 1,3-dicarbonyls as starting materials.
However, these methods suffer from low yields and exhibit
limited substrate tolerance and reactivity. Keeping this in mind,
we envisioned the catalyst-free three-component reaction of β-
chloroacroleins, 1,3-dicarbonyls and ammonium acetate to give
benzo[6,7]cyclohepta [1,2-b]pyridines using ethanol as reaction
medium. To the best of our knowledge, there is no report
concerning the catalyst-free three component synthesis of
benzo[6,7]cyclohepta [1,2-b]pyridines. This process was
established for the first time for the tandem construction of the
benzocycloheptapyridines.
In continuation to our program towards the development of
new protocols and their applications in the development of new
synthetic pathways for the preparation of cycle compounds, we
herein, report the synthesis of benzo[6,7]cyclohepta [1,2-
b]pyridines from β-chloroacroleins and 1,3-dicarbonyls which
was based on the use of cascade or one-pot reactions.14
Scheme2: Synthesis of (Z)-9-chloro-6,7-dihydro-5H-benzo[7]
annulene-8-carbaldehydes.
As part of our continuous research in the field of biologically
active heterocyclic compounds. We examined the reaction
Synthesis of benzo[6,7]cyclohepta[1,2-b]pyridine derivatives
(5a-n) was accomplished by Hantzsch type reaction via Michael
addition which involves reaction of aldehydes 2, 1,3-dicarbonyls
(3) with NH4OAc as amine source. Generally, such type
reactions are carried in the presence of acidic catalysts. However,
in the present study, more satisfactory results were obtained by
carrying out the reaction without using any catalyst.
between
(Z)-9-chloro-6,7-dihydro-5H-benzo[7]annulene-8-
carbaldehyde ,1,3-dicarbonyls and ammonium acetate without
using any catalyst. It is known that this reaction allows the
preparation of dihydropyridine derivatives by condensation of an
aldehyde with two equivalents of a β-ketoester in the presence of
ammonia source (Hantzsch Dihydropyridine Synthesis)17a-c and
that this product might be useful in biological screening purpose.
With this concept in mind, we began to investigate the reaction
First, we selected 9-chloro-2,3-dimethyl-6,7-dihydro-5H-
benzo[7]annulene-8-carbaldehyde,
methylacetoacetate
and
ammonium acetate as substrates and examined the reaction with
different solvents at reflux temperatures ranging from 8-12 h.
The best results were obtained when ethanol was used as a
solvent at reflux temperatures for 8 h. After preliminary
experimentation, it was found that a mixture of 1 equivalent of 9-
chloro-2,3-dimethyl-6,7-dihydro-5H-benzo[7]annulene-8-
with
(Z)-9-chloro-6,7-dihydro-5H-benzo[7]annulene-8-
carbaldehyde (β-chloroacroleins). An ethanol solution of (Z)-9-
chloro-6,7-dihydro-5H-benzo[7]annulene-8-carbaldehyde, 1,3-
dicarbonyls with NH4OAc as amine source was stirred at reflux
for 8h without using any catalyst. Surprisingly, the reaction
proceeded smoothly in the absence of catalyst to offer an
carbaldehyde, methyl acetoacetate and
ammonium acetate in the presence of ethanol at reflux
temperature for afforded methyl-2,9,10-trimethyl-6,7-
2 equivalents of
unexpected
product
benzo[6,7]cyclohepta[1,2-b]pyridine
derivative which is confirmed by different spectroscopic data
(scheme 1).
8
h
dihydro-5H-benzo[6,7] cyclohepta[1,2-b]pyridine-3-carboxylate
5a (Table 3, Entry a) in 85% yield. Subsequently, we
4

investigated on the use of different solvents for the purpose. In
aprotic solvents such as benzene and toluene, the reaction was
very slow and resulted in lower product yield. Similar results
were obtained in other solvents such as THF, acetonitrile. On the
other hand, performing the reaction using protic solvents such as
EtOH or MeOH; EtOH improved not only the rate of reaction but
also the yield of product as compared to MeOH. Finally, EtOH
proved promising as a solvent of choice for further reactions
(Table 1, Entry 1).
atoms which were absent in the starting material. Ester carbonyl
carbon gave signals at δ 167.3, whereas methyl carbon attached
to pyridine ring showed a signal at δ 24.6. The proposed structure
was substantiated by its mass spectra, which exhibited molecular
ion peak at m/z 296 [M+H]+.
To further conform the structure of the product based on the
X-ray diffraction data analysis (Crystal data for compound 5a,
AN30): C19H21NO2, M = 295.37, colorless block, 0.36 x 0.32 x
0.24 mm3, triclinic, space group P-1 (No. 2), a = 7.4807(8), b =
7.7633(9), c = 14.8941(17) Å, α = 77.051(2), β = 79.129(2), γ =
71.681(2)°, V = 793.70(15) Å3, Z = 2, Dc = 1.236 g/cm3, F000
=
Table 1: Optimization of the solvent.
316, CCD area detector, MoKα radiation,λ = 0.71073 Å, T =
293(2)K, 2θmax = 50.0º, 7659 reflections collected, 2790 unique
(Rint = 0.0186), Final GooF = 1.027, R1 = 0.0463, wR2 = 0.1256,
R indices based on 2141 reflections with I >2σ(I) (refinement on
F2), 203 parameters, µ = 0.080 mm-1. CCDC 997653 contains the
supplementary crystallographic data for this paper. These data
Entry
Solvent
Time(hr)
Yield (%)a
1
2
3
4
5
6
Ethanol
Methanol
8
85
60
10
15
15
15
20
Benzene
20
can
be
obtained
free
of
charge
from
at
the
Toluene
10
www.ccdc.cam.ac.uk/conts/retrieving.html
or
Cambridge Crystallographic Data Centre (CCDC), 12 Union
Road, Cambridge CB2 1EZ, UK; fax: +44(0) 1223 336 033;
email: deposit@ccdc.cam.ac.uk.
X-ray diffraction data for the compound were
collected at room temperature using a Bruker Smart Apex
Tetrahydrofuran
Traces
10
Acetonitrile
aIsolated yield after column chromatography
CCD diffractometer with graphite monochromated MoK
α
Various commercially available synthetic equivalents of
ammonia were tested to access pyridine derivative 5a (Table 2).
Finally the ammonium acetate with two equivalents was proved
to be the best ammonia source for the preparation of
benzo[6,7]cyclohepta[1,2-b]pyridine derivatives.
radiation (
λ
=0.71073Å) with ω-scan method.19 Preliminary
lattice parameters and orientation matrices were obtained
from four sets of frames. Unit cell dimensions were
determined using 2516 reflections for AN30
(5a).
Integration and scaling of intensity data were accomplished
using SAINT program.19 The structures were solved by
Direct Methods using SHELXS9720 and refinement was
carried out by full-matrix least-squares technique using
SHELXL97.20 Anisotropic displacement parameters were
included for all non-hydrogen atoms. All H atoms were
positioned geometrically and treated as riding on their parent
C atoms, with C-H distances of 0.93--0.97 Å, and with
Uiso(H) = 1.2Ueq (C) or 1.5Ueq for methyl atoms. The
structure is shown in Fig 2.
Table 2: Screening of the ammonia source in the test reaction
Entry
Ammonia
source
Amount(equiv.) Acid cat. Yield(%)a
1
2
3
NH4OAc
NH4OAc
NH4OAc
1
1.5
2
NO
NO
NO
50
60
85
4
5
NH4Cl
(NH4)2CO3
NH4OAc
NH4OAc
NH4OAc
NH4OAc
NH4OAc
2
2
2
2
2
2
2
NO
NO
traces
traces
40
6
AcOH
HCl
7
-
8
H2SO4
MsOH
CF3SO3H
-
9
traces
traces
10
aIsolated yield after column chromatography
The formation of compound 5a was evident from the ESI-MS
spectrum with the appearance of [M+H]+ peak at m/z 296, while
the FT-IR spectrum revealed the presence of absorption band at
1721 cm-1 which attributed to the presence of ester group, which
was obviously absent in 2b and the presence of ring carbonyl
group in 2b was resonated at 1670 cm-1. Further, in IR spectrum,
a broad absorption band at 1543 cm-1 indicated the formation of
pyridine ring in 5a. Similarly, the 1H NMR spectrum of 5a
exhibited singlet at δ 8.04 due to the presence of pyridine ring
proton. Aromatic protons showed multiplet at δ 7.52-7.01
whereas ester protons appeared as singlet at δ 3.94. To provide
further evidence for the proposed structure, 13C NMR was
recorded, which showed peaks at δ 52.0 due to ester carbon
Figure 2: X-ray crystal structure of AN30 (5a)
Encouraged by this success, we attempted the reaction of
substituted
(Z)-9-chloro-6,7-dihydro-5H-benzo[7]annulene-8-
carbaldehydes (β-chloroacroleins), with a range of other different
substituted 1,3-dicarbonyls, and ammonium acetate with ethanol
as a reaction medium under similar conditions furnishing the
respective benzo[6,7]cyclohepta[1,2-b]pyridine derivatives 5a-5n
(Scheme 1) in excellent yields. The optimized results are listed in
Table 3.
5

Table 3:
Entry
Synthesis ofbenzo[6,7]cyclohepta[1,2-b]pyridine derivatives
Product5(a-n)a
Yield (%)b,c
Substrate
1,3-dicarbonyls
O
CH3
H3C
N
CH3
O
H3C
O
85
Cl
O
1
H3C
O
H3C
H3C
H
O
CH3
5a
2b
Cl
O
CH3
84
82
H3
C
CH3
O
O
O
O
N
2
3
4
5
H
5b
O
O
O
CH3
2a
Cl
H3C
N
CH3
O
O
O
H
O
H3
C
O
CH3
5c
2a
O
H3C
CH3
O
H3C
Cl
N
83
80
80
O
O
H3
C
H3
C
H
H3C
O
CH3
H3C
5d
2b
O
Ph
N
CH3
O
O
O
Cl
O
Ph
O
CH3
H
5e
2a
O
Ph
N
CH3
H3C
H3C
O
Cl
O
O
O
H3C
H3C
6
7
Ph
O
CH3
H
5f
2b
O
H3C
N
CH3
Cl
O
O
O
79
H
H3C
CH3
5g
2a
O
H3C
CH3
O
O
H3C
H3C
N
Cl
O
80
82
H3
C
CH3
H3C
H3C
8
9
H
5h
O
2b
Ph
N
Ph
O
O
Cl
O
Ph
Ph
H
5i
2a
O
Ph
N
Ph
83
H3C
H3C
O
O
Cl
O
H3C
Ph
Ph
10
11
H
5j
H3
C
2b
CH3
H3C
H3C CH3
Cl
O
O
89
90
N
H
O
O
5k
2a
CH3
H3C
N
H3C CH3
H3C
H3C
O
Cl
O
O
O
H
H3C
H3C
12
5l
2b
O
Cl
O
N
91
92
O
O
H
5m
13
14
2a
O
H3C
H3C
Cl
N
O
H3
H3
C
C
O
O
H
5n
2b
aThe products were characterized by 1H NMR, IR and Mass Spectroscopy; bIsolated yield after
column chromatography;cAll the reactions were performed for 8h.
4

presence of ester group on pyridine ring in combination with
methyl group on C2 position. Further studies are underway to
optimize the lead molecule.
In general, all the reactions were very clean, and β-
chloroacroleins are vinyl chlorides, which were activated in the
presence of an electron-withdrawing group which have been
utilized extensively for
benzo[6,7]cyclohepta[1,2-b]pyridine derivatives in good to high
yields (79-92%) (Scheme and Table 3). Various 1,3-
the synthesis of various
Table-4: Inhibition efficacy of the synthesized compounds 5a-n
against inflammation for IL-1β and MCP-1.a
1
dicarbonyls containing acyclic and cyclic substituent’s showed
easy product formation in good to high yields. Results showed
that the cyclic substituent groups like 5,5-dimethylcyclohexane-
1,3-dione and cyclohexane-1,3-dione play a significant role in the
reactivity of the substrate and high yields were obtained (Table 3:
entry k, l, m, n; 89, 90, 91, 92 % yield).
S.No Compounds
IL-1β
MCP-1
% cell
viabilityd
98.3 3.5
(IC50 µM)b (IC50 µM)b
1
2
8.6 0.9
8.2 1.5
6.9 1.7
6.5 1.1
NA
16 1.8
NA
5a
97.2 1.3
99.2 2.8
95.9 3.1
103.2 4.9
97.6 2.7
92.3 5.8
5b
3
NA
5c
On the basis of all our experimental results, we have
proposed the plausible mechanism for the formation of
benzo[6,7]cyclohepta[1,2-b]pyridine derivatives (Scheme 3). The
hypothesis supported the fact that the reaction was initiated by
ammonium acetate, which reacted with 1,3-dicarbonyls for the
formation of enamine (X). The enamine (X) undergoes Michael
addition with β-chloroacroleins to give an intermediate (Y).
Further, the mechanism follows dehydrohalogenation,
intramolecular cyclization and aromatization giving rise to the
formation of compounds 5(a-n) (Scheme 3).
4
5d
8.5 2.1
NA
5
5e
6
18.2 1.5
NA
8.5 0.8
NA
5f
7
5g
8
NA
14.8 1.5 97.6 3.6
5h
9
17.5 0.7
NA
NA
NA
99.4 0.9
101.3 2.3
98.2 4.4
105.2 3.8
96.8 2.9
97.1 4.0
98.1 2.2
5i
10
11
12
13
14
5j
NA
5.6 1.5
NA
5k
5l
NA
NA
NA
5m
5n
NA
NA
piroxicamc
18.1 1.4
NT
a THP1 monocytes were pre-treated with 5, 10 and 20 µM concentrations of
the above mentioned benzo[6,7]cyclohepta[1,2-b]pyridine derivatives (5 a-n)
for 2 h followed by simulation with 100 nM of phorbol 13-myristate 12-
acetate (PMA) to induce inflammation for a period of 48 h. At the end of the
treatment, conditioned media was collected and levels of IL-1β and MCP-1
were measured by ELISA as described in the Materials and Methods.
b IC50 values are mean SD of three independent experiments, NA: indicates
activity >20 µM.
c Piroxicam, a known anti-inflammatory agent is used as a positive control.
dTHP-1 cell viability with synthesized compounds (20 µM).
Scheme 3. Plausible mechanism for the synthesis of
benzo[6,7]cyclohepta[1,2-b]pyridine derivatives
In conclusion, we have demonstrated a highly efficient
approach for the synthesis of benzo[6,7]cyclohepta[1,2-
All the synthesized compounds of benzo[6,7]cyclohepta[1,2-
b]pyridine derivatives (5a-n) were screened for anti-
inflammatory activity in PMA (Phorbol 13-Myristate 12-acetate)
stimulated THP-1 monocytes by measuring the levels of IL-1β
and MCP-1 with reference to piroxicam and the results are
summarized in the Table 4. Among the tested compounds 5a, 5d
and 5f inhibited both IL-1β and MCP-1 activities. Compound 5b,
5c and 5i showed only IL-1β activity whereas compounds 5h and
5k showed only MCP-1 activity.
b
]pyridine derivatives by treatment of the corresponding
1,3-dicarbonyls with -chloroacroleins and ammonium
β
acetate by using ethanol as medium without addition of any
catalyst. The synthetic approach demonstrated here is based
on a simple one-pot procedure and allows for the syntheses
of benzo[6,7]cyclohepta[1,2-b]pyridine is promisingly
applicable for the syntheses of other pyridyl compounds.
This method is simple, convenient and catalyst-free to
produce the structural diversity in a one-pot process of
various products (5a
5b 5c 5d 5f, and 5k) showed impressive anti-inflammatory
activities (IL-1 and MCP-1) at micro molar concentration
which was found to be better than positive control i.e.
piroxicam.
-5n). Among them six compounds (5a,
It was found that compounds 5a, 5b, 5c, 5d showed potent
activity against IL-1β with IC50 8.6, 8.2, 6.9, 6.5 µM. Compounds
5d, 5f, 5k showed potent activity against MCP-1 with IC50 8.5,
8.5, 5.6 µM. Under the same condition, piroxicam showed an
IC50 of 18.1 µM (IL-1β) Table 4. On the other hand, none of the
compounds had any effect on cell viability even at 20 µM
concentration. This result clearly indicates that the anti-
inflammatory activities of these compounds are not due to the
induction of cytotoxicity in these cells. The structure activity
relationship revealed that the activity is further enhanced in the
,
,
,
β
5

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Acknowledgements
The authors are gratefully acknowledged to the DST-
SERB/EMEQ-078/2013 for the financial support. YK and HR
thanks CSIR, New Delhi for research fellowships.
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1
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4

Graphical Abstract
Three-component, one-pot synthesis of benzo[6,7]cyclohepta
[1,2-b]pyridine derivatives under catalyst free conditions and
evaluation of their anti-inflammatory activity
Leave this area blank for abstract info.
Yasodakrishna Sajjaa, Hanmanth Reddy Vulupalaa, Rajashaker Bantua, Lingaiah Nagarapua*, Sathish Babu
Vasamsettib, Srigiridhar Kotamrajub, Jagadeesh Babu Nanuboluc
An efficient protocol has been developed for the synthesis of benzo[6,7]cyclohepta[1,2-b]pyridine derivatives with β-
chloroacroleins, 1,3-dicarbonyls and ammonium acetate without any catalyst as potent anti-inflammatory agents.
1