Synthesis, topoisomerase I and II inhibitory activity, cytotoxicity, and structure-activity relationship study of 2-phenyl- or hydroxylated 2-phenyl-4-aryl-5H-indeno[1,2-b]pyridines

Article abstract of DOI:10.1016/j.bmc.2015.04.031

Abstract A series of novel twenty-eight rigid 2-phenyl- or hydroxylated 2-phenyl-4-aryl-5H-indeno[1,2-b]pyridines were synthesized and evaluated for their topoisomerase inhibitory activity as well as their cytotoxicity against several human cancer cell li

Full text of DOI:10.1016/j.bmc.2015.04.031

Accepted Manuscript
Synthesis, topoisomerase I and II inhibitory activity, cytotoxicity, and structure-
activity relationship study of 2-phenyl- or hydroxylated 2-phenyl-4-aryl-5H-
indeno[1,2-b]pyridines
Tara Man Kadayat, Chanju Song, Somin Shin, Til Bahadur Thapa Magar,
Ganesh Bist, Aarajana Shrestha, Pritam Thapa, Younghwa Na, Youngjoo Kwon,
Eung-Seok Lee
PII:
S0968-0896(15)00329-6
DOI:
http://dx.doi.org/10.1016/j.bmc.2015.04.031
BMC 12243
Reference:
To appear in:
Bioorganic & Medicinal Chemistry
Received Date:
Revised Date:
Accepted Date:
9 January 2015
23 March 2015
10 April 2015
Please cite this article as: Kadayat, T.M., Song, C., Shin, S., Thapa Magar, T.B., Bist, G., Shrestha, A., Thapa, P.,
Na, Y., Kwon, Y., Lee, E-S., Synthesis, topoisomerase I and II inhibitory activity, cytotoxicity, and structure-activity
relationship study of 2-phenyl- or hydroxylated 2-phenyl-4-aryl-5H-indeno[1,2-b]pyridines, Bioorganic &
Medicinal Chemistry (2015), doi: http://dx.doi.org/10.1016/j.bmc.2015.04.031
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‘REVISED’
Synthesis, topoisomerase I and II inhibitory activity, cytotoxicity, and structure-activity
relationship study of 2-phenyl- or hydroxylated 2-phenyl-4-aryl-5H-indeno[1,2-
b]pyridines
a,#
b,#
b
a
a
Tara Man Kadayat, Chanju Song, Somin Shin, Til Bahadur Thapa Magar, Ganesh Bist,
a
a
c
b,*
a,*
Aarajana Shrestha, Pritam Thapa, Younghwa Na, Youngjoo Kwon, Eung-Seok Lee
a
b
College of Pharmacy, Yeungnam University, Gyeongsan 712-749, Republic of Korea
College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Global Top5
program, Ewha Womans University, Seoul 120-750, Republic of Korea
c
College of Pharmacy, Cha University, Pochon 487-010, Republic of Korea
*
Corresponding Authors:
Tel: +82 2 3277-4653, fax: +82 2 3277-2851, email: ykwon@ewha.ac.kr (Y.K.)
Tel: +82 53 810-2827, fax: +82 53 810-4654, email: eslee@yu.ac.kr (E.-S.L.)
#
Authors are equal contributors
1

Synthesis, topoisomerase I and II inhibitory activity, cytotoxicity, and structure-activity
relationship study of 2-phenyl- or hydroxylated 2-phenyl-4-aryl-5H-indeno[1,2-
b]pyridines
a,#
b,#
b
a
a
Tara Man Kadayat, Chanju Song, Somin Shin, Til Bahadur Thapa Magar, Ganesh Bist,
a
a
c
b,*
a,*
Aarajana Shrestha, Pritam Thapa, Younghwa Na, Youngjoo Kwon, Eung-Seok Lee
a
b
College of Pharmacy, Yeungnam University, Gyeongsan 712-749, Republic of Korea
College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Global Top5
program, Ewha Womans University, Seoul 120-750, Republic of Korea
c
College of Pharmacy, Cha University, Pochon 487-010, Republic of Korea
Abstract
A series of novel twenty-eight rigid 2-phenyl- or hydroxylated 2-phenyl-4-aryl-5H-
indeno[1,2-b]pyridines were synthesized and evaluated for their topoisomerase inhibitory
activity as well as their cytotoxicity against several human cancer cell lines. Generally,
hydroxylated compounds (16-18, 22-25, and 29-31) containing furyl or thienyl moiety at 4-
position of central pyridine exhibited strong topoisomerase I and II inhibitory activity
compared to positive control, camptothecin and etoposide, respectively, in low micromolar
range. Structure-activity relationship study revealed that indenopyridine compounds with
hydroxyl group at 2-phenyl ring in combination with furyl or thienyl moiety at 4-position are
important for topoisomerase inhibition. Compounds (22-25) which contain hydroxyl group at
meta position of the 2-phenyl ring at 2-position and furanyl or thienyl substitution at 4-
position of indenopyridne, showed concrete correlations between topo I and II inhibitory
2

activity, and cytotoxicity against evaluated human cancer cell lines.
Keywords: Hydroxylated 2-phenyl-4-aryl-5H-indeno[1,2-b]pyridines; Anticancer agents;
Topoisomerase I and II inhibitor; Cytotoxicity
Introduction
DNA topoisomerases are one of the established molecular targets for the development of
anticancer agents. They have an important role in solving the DNA topological hurdles during
DNA replication by their activity of transiently breaking and rejoining of one or two strands
1
-3
of DNA. The human DNA topoisomerases are generally classified into topoisomerase I
4
(
topo I) and topoisomerase II (topo II). In the course of several years of its discovery,
topoisomerase inhibitors such as camptothecin, etoposide, and teniposide have been clinically
used for treatment of cancer. However, due to their severe side effects during therapy,
extensive research is going on for the development of a novel class of topoisomerase
5
, 6
inhibitors with improved therapeutic efficacy and reduced toxicities.
Terpyridine, which has ability to form metal complexes, and act as DNA binding agents, has
7
-9
been precious in antitumor research. In general, rigid compounds, as compared to flexible
structures, have little conformational entropy, and can be more efficiently fitted into the
1
0
11
active site of enzyme, and intercalate into the enzyme-DNA complex. Moreover, it has
been reported that compounds containing indenopyridine moiety showed several biological
1
2-14
activities such as anticancer and anti-inflammatory activity.
Therefore, our research group
has recently synthesized 2,4-diaryl-5H-indeno[1,2-b]pyridines (Fig. 1d) as conformationally
constrained rigid molecule in terpyridine skeleton, which showed moderate topoisomerase
1
5
inhibitory activity and cytotoxicity. As part of our continuous search for designing and
3

exploring newer anticancer agents, we incorporated the hydroxyl group on 2- phenyl moiety
to investigate the effect on topoisomerase I and II inhibitory activities and cytotoxicity (Fig.
1
f). A number of naturally occurring biologically active polyphenolic compounds such as
1
6-18
resveratrol, curcumin, epigallocatechin gallate,
are reported to possess antioxidant, anti-
Therefore, they are viewed as an important
pharmacophore in the field of anticancer drug discovery. It is observed that hydroxyl moiety
1
9-22
inflammatory, and anticancer activity.
2
3, 24
present in the flavonoids have important role for the topoisomerase inhibitory activity.
2
5-29
These promising reports on the importance of hydroxyl moiety and our previous results,
motivated us to observe the difference on biological activities by introducing hydroxyl group
on 2-phenyl ring in combination with thienyl, furyl and pyridyl moiety on the 4-position of
the indenopyridine skeletons.
Herein, we represent systematic design, synthesis and biological studies of twenty-eight
novel rigid analogs of 2-phenyl-4-aryl-5H-indeno[1,2-b]pyridines with or without hydroxyl
groups at different positions (ortho, meta, or para) of the 2- phenyl ring, and thienyl, furyl
and pyridyl groups attached to the 4-position of central pyridine as shown in Scheme 1 and
Fig. 2. The evaluation of biological activities of these compounds was carried out for topo I
and II inhibitory activity, and cytotoxicity against several human cancer cell lines. Moreover,
structure-activity relationship study was determined with respect to non-hydroxylated 2-
phenyl-4-aryl-5H-indeno[1,2-b]pyridines (8-14), and 2,4-diphenyl indenopyridine (36), with
hydroxylated 2-phenyl-4-aryl-5H-indeno[1,2-b]pyridines (15-35). This systematic study
represents synthesis and characterization of new 2-phenyl- or hydroxylated 2-phenyl-4-aryl-
5
H-indeno[1,2-b]pyridines to develop novel anticancer agents.
4

(
Figure 1)
2
. Results and Discussion
2
. 1. Synthetic chemistry
2
-Phenyl-4-aryl-5H-indeno[1,2-b]pyridine (8-35) were designed and synthesized based on
3
0, 31
the previously reported methods
as summarized in Scheme 1. At first, 1-indanone (1) was
1
1
condensed with aryl aldehydes 2 (R =a-g) to prepare intermediates 3 (R =a-g) in the presence
of 5% aqueous NaOH in ethanol. In the second step, four pyridinium iodide salts 4-7 were
synthesized by refluxing acetophenones with iodine in pyridine. Finally, using modified
1
Kröhnke synthesis, indanone intermediates 3 (R =a-g) and pyridinium iodide salts (4-7) were
reacted in the presence of ammonium acetate in methanol or acetic acid to give final
compounds 8-35 in 22.3-67.5% yield.
Total twenty-eight (8-35) rigid analogs, 2-phenyl-4-aryl-5H-indeno[1,2-b]pyridine, of 2,4,6-
trisubstituted pyridines were synthesized from the reaction of seven indanone intermediates
and four pyridinium iodide salts in four different series (Fig. 3). Among the twenty-eight
compounds, twenty-one compounds were monohydroxylated having hydroxyl group
substitution at ortho, meta, or para position of 2-phenyl moiety, while compound 36 has been
3
2
synthesized and reported previously. The substitutions of hydroxyl groups at various
positions of the phenyl ring allowed us to investigate the effect of the position of hydroxyl
group on biological activity. Furthermore, we were able to correlate the effect of
hydroxylated and non-hydroxylated 2-phenyl-4-aryl-5H-indeno[1,2-b]pyridine on biological
activity. Structures of the prepared compounds with different substitution pattern together
with yield, HPLC purity and melting point is illustrated in Fig. 2 and Table 1.
5

(
(
(
(
Scheme 1)
Figure 2)
Figure 3)
Table 1)
2
. 2. Topo I and II inhibitory activity
Inhibition against relaxation activity of topo I and II was measured by detecting the
conversion of supercoiled pBR322 DNA to its relaxed form in the presence of prepared 2-
phenyl-4-aryl indenopyridines 8-35. Camptothecin and etoposide, clinically used selective
topo I and II inhibitors, respectively, were used as positive controls. Inhibitory activities were
evaluated both at 100 µM and 20 µM. The reaction products were analyzed by
electrophoretic mobility and developed in ethidium bromide in the presence of UV light.
Fig. 4 and Table 2 illustrates the topo I inhibitory activity of prepared compounds 8-36.
Several compounds 8, 18, 20-25, 27, 30-35 have shown significant topo I inhibitory activity
at 100 µM. Interestingly, except compound 8 with significant activity of 73.0% at 100 µM (as
compared to 58.0% of camptothecin), all the compounds having no hydroxyl group at 2-
phenyl ring of central pyridine (9-14) showed very weak topo I inhibitory activity. Almost all
the compounds with hydroxyl group at 2-phenyl ring exhibited significant topo I inhibitory
activity at 100 µM concentration. Compounds 32 has shown the most significant topo I
inhibition (90.1% as compared to 58.4% of camptothecin) at 100 µM.
As shown in Fig. 5 and Table 2, compounds 8, 16, 22-27, 29, and 30 exhibited significant
6

topo II inhibition at 100 µM and 20 µM concentration which showed stronger or comparable
to etoposide. Compound 22 showed the strongest topo II inhibitory activity, 78.2% and
4
4.5% at 100 µM and 20 µM, respectively which is stronger than that of etoposide (55.5%
and 28.4%, respectively). Similarly, compound 25 displayed 77.2% and 37.0% inhibition,
and compound 29 exhibited 59.9% and 44.2% inhibition at 100 µM and 20 µM, respectively.
Compounds 9, 17, 18, 31, 32, 34, and 35 showed moderate topo II inhibitory activity.
It was observed that compounds 8, 22-25, and 30 showed both strong topo I and II inhibitory
activities.
(
(
(
Figure 4)
Figure 5)
Table 2)
2
. 3. Cytotoxicity
All the synthesized compounds were evaluated for cytotoxicity against four different human
cancer cell lines: HCT 15 (human colorectal adenocarcinoma cell line), T47D (human breast
ductal carcinoma cell line), DU145 (human prostate tumor cell line), and HeLa (human
cervix adenocarcinoma cell line). Adriamycin, camptothecin, and etoposide were used as
positive controls. The inhibitory activities (IC values) of the synthesized 2-phenyl-4-aryl
5
0
indenopyridines (8-35) against several cancer cell lines are listed in Table 2. Most of the
compounds possessing both strong topo I and II inhibitory activities showed significant
cytotoxicity. Especially, compounds 8 and 22-25 showed almost equivalent cytotoxicity to
positive controls in all the evaluated human cancer cell lines.
7

2
.4. Structure-activity relationship study
Structure-activity relationship study was performed according to the results of topo I and II
inhibitory activity of the evaluated compounds. Compounds from series 1 (8-14, Scheme 1),
except compound 8, all of the non-hydroxylated compounds displayed weaker topo I
inhibitory activity than hydroxylated compounds at 100 µM. As shown in Table 2,
hydroxylated compounds (16-18, 22, 24, 25, 27, and 29-31) exhibited potent topo I and II
inhibition as compared to non-hydroxylated compounds (9-14, and 36). In addition, unlike
1
5
previous study performed by our research group, in this study, most of the hydroxylated
compounds found to be potent as they showed moderate to significant topo II inhibitory
activity even in low micromolar concentration with a few exceptions. Similarly, except
compound 26, all the hydroxylated compounds displayed moderate to significant topo I
inhibitory activity at 100 µM concentration. From these results, it could be implied that
introduction of hydroxyl moiety at phenyl ring of 2-phenyl-4-aryl-5H-indeno[1,2-b]pyridines
2
5, 26, 28
would increase topo I and II inhibitory activities. These findings, as reported earlier,
support that introduction of hydroxyl groups on phenyl ring enhance the topo I and topo II
inhibitory activity of the 2-phenyl-4-aryl indenopyridines.
Moreover, in addition to introduction of hydroxyl group of the 2-phenyl ring at 2-position of
the central pyridine, substitution with furyl or thienyl group (16-18, 22-25 and 29-31) at 4-
position of the central pyridine displayed moderate to significant topo I and II inhibitory
activity. In contrast, except compound 27, all the compounds bearing pyridyl moiety at 4-
position of the central pyridine did not show any significant dual topo inhibition. This finding
25, 33-35
which was similar to previous studies,
also supports the idea of importance of furyl or
thienyl moiety at 4-position of central pyridine than pyridyl or phenyl moiety for significant
8

topo I and II inhibitory activity (Fig. 6).
Structure-activity relationship study related to topo inhibitory activities and cytotoxicity was
performed. As shown in table 2, since not so many compounds showed significant
cytotoxicity, it was not enough to draw out correlation between topo inhibition and
cytotoxicity. However, compounds (22 – 25) which contain hydroxyl group at meta position
of the 2-phenyl ring at 2-position and furanyl or thienyl substitution at 4-position of
indenopyridne, showed concrete correlations between topo I and II inhibitory activity, and
cytotoxicity against evaluated human cancer cell lines. The results indicated that importance
of introduction of 2-phenyl ring at 2-position and furanyl or thienyl substitution at 4-position
of indenopyridne, which are responsible for topo inhibitory activities and cytotoxicity. It is
interesting to note that compound 8 possessing 2-phenyl ring at 2-position and 2-furanyl
substitution at 4-position of indenopyridne showed strong dual topo inhibition and
cytotoxicity against evaluated human cancer cell lines.
(
Figure 6)
3
. Conclusion
Total twenty-eight
2-phenyl-4-aryl-5H-indeno[1,2-b]pyridines
derivatives
were
systematically designed and synthesized by efficient synthetic routes, and evaluated them for
topo I and II inhibitory activities, and cytotoxicity against several human cancer cell lines.
Evaluation of the topoisomerase inhibitory activity revealed that introduction of hydroxyl
moiety on 2-phenyl ring of indenopyridines increases potency of the compounds for topo I
and II inhibition. The structure-activity relationship study revealed that hydroxylated 2-
9

phenyl-4-aryl-5H-indeno[1,2-b]pyridines with furyl or thienyl moiety at 4- position of central
pyridine exhibited moderate to significant topo I and II inhibitory activity. Interestingly,
compounds containing meta-hydroxyl moiety at 2-phenyl ring of the central pyridine in
combination with furyl, or thienyl moiety at 4-position rather than pyridyl or phenyl moiety
at 4-position is more important for cytotoxicity. This study may provide valuable information
to medicinal chemist working in the field of cancer research.
4
. Experimental
Compounds used as starting materials and reagents were obtained from Aldrich Chemical Co.,
Junsei or other chemical companies, and used without further purification. HPLC grade
acetonitrile (ACN) and methanol were purchased from Burdick and Jackson, USA. Thin-
layer chromatography (TLC) and column chromatography (CC) were performed with
Kieselgel 60 F254 (Merck) and silica gel (Kieselgel 60, 230-400 mesh, Merck) respectively.
Since all the prepared compounds contained aromatic ring, they were visualized and detected
on TLC plates with UV light (short wave, long wave or both). NMR spectra were recorded on
1
13
a Bruker AMX 250 (250 MHz, FT) for H NMR and 62.5 MHz for C NMR, and chemical
shifts were calibrated according to TMS. Chemical shifts (δ) were recorded in ppm and
coupling constants (J) in hertz (Hz). Melting points were determined in open capillary tubes
on electrothermal 1A 9100 digital melting point apparatus and were uncorrected.
HPLC analyses were performed using two Shimadzu LC-10AT pumps gradient-controlled
HPLC system equipped with Shimadzu system controller (SCL-10A VP) and photo diode
array detector (SPD-M10A VP) utilizing Shimadzu Class VP program. Sample volume of 10
®
μL was injected in Waters X-Terra 5 μM reverse-phase C1 column (4.6 ⅹ250 mm) with a
8
1
0

gradient elution of 70% to 100% of B in A for 10 min followed by 100% to 70% of B in A for
0 min at a flow rate of 0.5 mL/min at 254 nm UV detection, where mobile phase A was
2
solution (20 mM) of ammonium formate (AF) in doubly distilled water and B was 100%
acetonitrile (ACN). Purity of compounds was described as percent (%) and retention time
was given in minutes. ESI LC/MS analyses were performed with a Finnigan LCQ
®
®
Advantage LC/MS/MS spectrometry utilizing Xcalibur program. For ESI LC/MS, LC was
®
performed with a 8 μL injection volume on a Waters Atlantis T reverse-phase C column
3
18
(
2.1ⅹ 50 mm, 3 μm) with a gradient elution from; (A) 50% to 90% of B in A for 4 min and
remained linear 90% of B in A for 1 min followed by 90% to 50% of B in A for 3 min and
remained linear 50% of B in A for 7 min at flow rate of 200 μL/min; (B) 50% to 90% of B in
A for 5 min followed by 90% to 50% of B in A for 5 min and remained linear 50% of B in A
for 5 min at flow rate of 200 μL/min, where mobile phase A was solution (20 mM) of
ammonium formate (AF) in doubly distilled water and mobile phase B was 100% ACN. MS
ionization conditions were: Sheath gas flow rate: 40 arb, aux gas flow rate: 0 arb, I spray
voltage: 5.3 KV, capillary temperature: 275°C, capillary voltage: 27 V, tube lens offset: 45 V.
4
. 1. General method for the preparation of 3
1
Total seven 1H-inden-1-one derivatives 3 (R = a-g) were synthesized by base catalyzed
1
5
Claisen-Schmidt condensation reaction as reported previously. 1-Indanone (1) was added in
1
ethanol followed by the addition of equivalent amount of aryl aldehydes 2 (R = a-h). The
5
% aqueous solution of NaOH was added drop wise to the mixture at 0 °C which resulted in
precipitation. The mixture was then cooled for 30 min, filtered, washed with cold methanol,
and dried to yield 90.1-99.8% solid compound.
1
1

4
.1.1. Synthesis of 2-(furan-2-ylmethylene)-2,3-dihydro-1H-inden-1-one (3a)
The procedure described in Section 4.1 was employed with 1-indanone (1, 1.32 g, 10 mmol)
and 2-furaldehyde (2a, 0.82 mL, 10 mmol) to yield 1.89 g (9.01 mmol, 90.1%) as a yellow
solid.
o
TLC (ethyl acetate / n-hexane = 1:5) R = 0.28, mp: 124.2-125.6 C, HPLC: Retention time:
f
+
1
1.62 min, purity: 97.8%; ESI LC/MS (condition A): m/z calcd for C H O [MH] 211.08;
1
4
10
2
found 211.14
1
H NMR (250 MHz, CDCl ) δ 7.88 (d, J = 7.64 Hz, 1H, indeno H-7), 7.63 (s, 1H, =CH-),
3
7
.61-7.53 (m, 2H, furan H-5, indeno H-5), 7.47-7.39 (m, 2H, indeno H-4, H-6), 6.77 (d, J =
3
.4 Hz, 1H, furan H-3), 6.56 (br, 1H, furan H-4), 4.05 (s, 2H, indeno H-3).
1
3
C NMR (62.5 MHz, CDCl ) δ 193.97, 152.27, 149.76, 145.35, 138.45, 134.42, 132.53,
3
1
27.44, 126.17, 124.20, 120.03, 116.61, 112.64, 32.32.
4
.1.2. Synthesis of 2-(furan-3-ylmethylene)-2,3-dihydro-1H-inden-1-one (3b)
The procedure described in Section 4.1 was employed with 1-indanone (1, 1.32 g, 10 mmol)
and 3-furaldehyde (2b, 0.83 mL, 10 mmol) to yield 1.98 g (9.46 mmol, 94.6%) as whitish
yellow solid.
o
TLC (ethyl acetate / n-hexane = 1:5) R = 0.2, mp: 139.6-141.1 C, HPLC: Retention time:
f
+
1
1.10 min, purity: 97.5%; ESI LC/MS (condition A): m/z calcd for C H O [MH] 211.08;
1
4
10
2
found 211.12
1
H NMR (250 MHz, CDCl ) δ 7.89 (d, J = 7.6 Hz, 1H, indeno H-7), 7.82 (s, 1H, =CH-),
3
7
.65-7.52 (m, 4H, indeno H-4, H-5, furan H-2, H-5), 7.4 (t, J = 7.27 Hz, 1H, indeno H-6), 6.7
(
d, J = 1.6 Hz, 1H, furan H-4), 3.89 (s, 2H, indeno H-3).
1
2

1
3
C NMR (62.5 MHz, CDCl ) δ 193.87, 148.95, 145.77, 144.29 138.32, 134.47, 133.83,
3
1
27.57, 126.14, 124.21, 123.99, 122.41, 109.91, 31.89.
4
.1.3. Synthesis of 2-(thiophen-2-ylmethylene)-2,3-dihydro-1H-inden-1-one (3c)
The procedure described in Section 4.1 was employed with 1-indanone (1, 1.32 g, 10 mmol)
and 2-thiophene carboxaldehyde (2c, 0.93 mL, 10 mmol) to yield 2.16 g (9.56 mmol, 95.6%)
as a white solid.
o
TLC (ethyl acetate / n-hexane = 1:5) R =0.25, mp:172.2-173.1 C, HPLC: Retention time:
f
+
1
2.53 min, purity: 100%; ESI LC/MS (condition A): m/z calcd for C H OS [MH] 227.05;
1
4
10
found 227.13
1
H NMR (250 MHz, CDCl ) δ 7.90-7.88 (m, 2H, thiophene H-3, H-5), 7.62-7.55 (m, 3H,
3
indeno H-4, H-5, H-7), 7.45-7.42 (m, 2H, =CH-, indeno H-6), 7.17 (t, J = 4.97 Hz, 1H,
thiophene H-4), 3.93 (s, 2H, indeno H-3).
1
3
C NMR (62.5 MHz, CDCl ) δ 193.73, 149.03, 139.94, 138.57, 134.50, 133.01, 132.80,
3
1
30.44, 128.17, 127.64, 126.51, 126.21, 124.30, 32.34.
4
.1.4. Synthesis of 2-(thiophen-3-ylmethylene)-2,3-dihydro-1H-inden-1-one (3d)
The procedure described in Section 4.1 was employed with 1-indanone (1, 1.32 g, 10 mmol)
and 3-thiophene carboxaldehyde (2d, 0.91 mL, 10 mmol) to yield 2.1 g (9.29 mmol, 92.8%)
as a whitish brown solid.
o
TLC (ethyl acetate / n-hexane = 1:5) R =0.3, mp: 147.9-148.6 C, HPLC: Retention time:
f
+
1
2.21 min, purity: 96.9%; ESI LC/MS (condition A): m/z calcd for C H OS [MH] 227.05;
1
4
10
found 227.12
1
H NMR (250 MHz, CDCl ) δ 7.88 (d, J = 7.6 Hz, 1H, indeno H-7), 7.70-7.66 (m, 2H,
3
1
3

thiophene H-2, H-5), 7.64 (dt, J = 7.8, 1.12 Hz, 1H, indeno H-5), 7.56 (d, J = 7.07 Hz, 1H,
indeno H-4), 7.44-7.38 (m, 3H, =CH-, indeno H-6, thiophene H-4), 3.96 (s, 2H, indeno H-3).
1
3
C NMR (62.5 MHz, CDCl ) δ 194.25, 149.21, 138.45, 137.76, 134.49, 133.44, 129.46,
3
1
28.30, 127.65, 127.26, 126.60, 126.16, 124.32, 32.34.
4
.1.5. Synthesis of -2-(pyridin-2-ylmethylene)-2,3-dihydro-1H-inden-1-one (3e)
The procedure described in Section 4.1 was employed with 1-Indanone (1, 1.32 g, 10 mmol)
and 2-pyridine carboxaldehyde (2e, 0.95 mL, 10mmol) to yield 2.01 g (9.19 mmol, 91.9%) as
a white solid.
o
TLC (ethyl acetate / n-hexane = 1:5) R = 0.18, mp: 152.8-155.3 C, HPLC: Retention time:
f
+
1
0.98 min, purity: 98.2%; ESI LC/MS (condition A): m/z calcd for C H NO [MH] 222.09;
1
5
11
found 222.21
1
H NMR (250 MHz, CDCl ) δ 8.74 (br, 1H, pyridine H-6), 7.89 (d, J = 7.62 Hz, 1H, indeno
3
H-7), 7.71 (dt , J = 7.05, 0.9 Hz, 1H, pyridine H-3) 7.62-7.57 (m, 3H, =CH-, indeno H-4, H-
5
), 7.51 (d, J = 7.92 Hz, 1H, pyridine H-4), 7.38 (t, J = 7.27 Hz, 1H, indeno H-6), 7.21-7.19
(
m, 1H, pyridine H-5), 4.28 (s, 2H, indeno H-3).
1
3
C NMR (62.5 MHz, CDCl ) δ 194.89, 154.88, 151.24, 150.05, 139.11, 137.94, 136.35,
3
1
34.80, 130.94, 127.36, 127.35, 126.32, 124.37, 122.95, 33.37.
4
.1.6. Synthesis of 2-(pyridin-3-ylmethylene)-2, 3-dihydro-1H-inden-1-one (3f)
The procedure described in Section 4.1 was employed with 1-indanone (1, 1.98 g, 15 mmol)
and 3-pyridine carboxaldehyde (2f, 1.42 mL, 15 mmol) to yield 3.31 g (11.97 mmol, 99.8 %)
as a white solid.
1
4

TLC (ethyl acetate / n-hexane = 1:1) R =0.23, mp: 159.3-160.7 °C, HPLC: Retention time:
f
+
1
1.19 min, purity: 96.4%; ESI LC/MS (condition A): m/z calcd for C H NO [MH] 222.09;
1
5
11
found 222.21
1
H NMR (250 MHz, CDCl ) δ 8.93 (s, 1H, pyridine H-2), 8.63 (br, 1H, pyridine H-6), 7.98-
3
7
7
.91 (m, 2H, pyridine H-4, indeno H-7), 7.67-7.56 (m, 3H, =CH-, indeno H-4, H-5), 7.48-
.38 (m, 2H, pyridine H-5, indeno H-6), 4.04 (s, 2H, indeno H-3).
1
3
C NMR (62.5 MHz, CDCl ) δ 193.69, 151.61, 150.04, 149.30, 137.66, 136.89, 136.77,
3
1
34.97, 131.27, 130.03, 127.89, 126.23, 124.60, 123.73, 32.33.
4
.1.7. Synthesis of 2-(pyridin-4-ylmethylene)-2, 3-dihydro-1H-inden-1-one (3g)
The procedure described in Section 4.1 was employed with 1-indanone (1, 0.66 g, 5 mmol)
and 4-pyridine carboxaldehyde (2g, 0.47 mL, 5 mmol) to yield 1.09 g (4.93 mmol, 99.4 %) as
a white solid.
TLC (ethyl acetate / n-hexane = 3:1) R =0.29, mp: 182.1-183.4 °C, HPLC: Retention time:
f
+
9
.43 min, purity: 97.5%; ESI LC/MS (condition A): m/z calcd for C H NO [MH] 222.09;
1
5
11
found 222.21
1
H NMR (250 MHz, CDCl ) δ 8.68 (br, 2H, pyridine, H-2, H-6), 7.80 (d, J = 7.6 Hz, 1H,
3
indeno H-7), 7.76-7.65 (m, 4H, =CH-, indeno H-4, H-5, H-6), 7.51-7.48 (m, 2H, pyridine H-3,
H-5), 4.17 (s, 2H, indeno H-3).
1
3
C NMR (62.5 MHz, CDCl ) δ 194.05, 151.19, 151.07, 142.76, 140.41, 137.65, 136.34,
3
1
30.73, 128.77, 127.65, 125.15, 124.74, 32.63.
1
5

4
. 2. General method for the preparation of 4-7
A mixture of equivalent amount of acetophenones and iodine in pyridine (15 equiv.) was
refluxed for 3 h. After cooling the mixture to room temperature, the precipitate was filtered
and washed with cold pyridine followed by drying overnight to yield 66.8-93.1% of 4-7.
4
.3. General method for the preparation of 8-35
Anhydrous ammonium acetate (10.0 equiv.) was mixed with glacial acetic acid or methanol
1
followed by addition of the indanone intermediates (1.0 equiv.), 3 (R = a-h) and pyridinium
iodide salts 4-7 (1.0 equiv.). The mixture was then refluxed for 12-36 h. The reaction mixture
was then extracted with ethyl acetate, washed with water and brine solution. The organic
layer was dried with magnesium sulfate and filtered. The filtrate was evaporated at reduced
pressure, which was then purified with silica gel column chromatography with the gradient
elution of ethyl acetate/n-hexane to afford solid compounds 8-35 in 22.3-67.5% yield.
4
.3.1. Synthesis of 4-(furan-2-yl)-2-phenyl-5H-indeno[1,2-b]pyridine (8)
1
The same procedure described in section 4.3 was employed with 3 (R =a) (0.84 g, 4 mmol),
anhydrous ammonium acetate (3.178 g, 40 mmol), 4 (1.3 g, 4 mmol) and glacial acetic acid
(
10 mL) to yield 324 mg (1.05 mmol, 26.2%) as a yellow solid.
o
TLC (ethyl acetate / n-hexane = 1:15) R = 0.28, mp: 141.5-142.8 C, HPLC: Retention time:
f
+
1
1.49 min, purity: 96.3%; ESI LC/MS (condition A): m/z calcd for C H NO [MH] 310.12;
2
2
15
found 310.35
1
H NMR (250 MHz, CDCl ) δ 8.25-8.16 (m, 3H, indenopyridine H-9 and 2-phenyl H-2, H-
3
6
), 7.97 (s, 1H, indenopyridine H-3), 7.64-7.44 (m, 7H, 4-furan H-5, 2-phenyl H-3, H-4, H-5
1
6

and indenopyridine H-6, H-7, H-8), 7 (d, J = 3.43 Hz, 1H, 4-furan H-3), 6.61 (dd, J = 3.4, 1.8
Hz, 1H, 4-furan H-4), 4.10 (s, 2H , indenopyridine H-5).
1
3
C NMR (62.5 MHz, CDCl ) δ 161.54, 156.93, 151.56, 143.95, 143.55, 140.91, 139.84,
3
1
1
34.24, 129.20, 128.75, 128.69 (2C), 127.37, 127.19, 127.14 (2C), 124.94, 121.93, 113.04,
12.13, 110.58, 35.52.
4
.3.2. Synthesis of 4-(furan-3-yl)-2-phenyl-5H-indeno[1,2-b]pyridine (9)
1
The same procedure described in section 4.3 was employed with 3 (R =b) (0.84 g, 4 mmol),
anhydrous ammonium acetate (3.17 g, 40 mmol), 4 (1.37 g, 4 mmol) and glacial acetic acid
(
12 mL) to yield 276 mg (0.88 mmol, 22.3%) as a yellow solid.
o
TLC (ethyl acetate / n-hexane = 1:15) R = 0.29, mp: 120.1-122.4 C, HPLC: Retention time:
f
+
9
.95 min, purity: 97.5%; ESI LC/MS (condition A): m/z calcd for C H NO [MH] 310.12;
2
2
15
found 310.33
1
H NMR (250 MHz, CDCl ) δ 8.21 (dd, J = 7.04, 1.46 Hz, 1H, indenopyridine H-9), 8.10
3
(
dd, J = 7.6, 1.47 Hz, 2H, 2-phenyl H-2, H-6), 8.01 (s, 1H, indenopyridine H-3), 7.72 (s, 1H,
4
-furan H-2), 7.62-7.60 (m, 2H, 4-furan H-5, indenopyridine H-7), 7.55-7.41 (m, 5H, 2-
phenyl H-3, H-4, H-5, indenopyridine H-6, H-8), 6.91-6.89 (m, 1H, 4-furan H-4), 3.97 (s, 2H,
indenopyridine H-5).
1
3
C NMR (62.5 MHz, CDCl ) δ 161.32, 157.13, 143.84, 143.6, 141.43, 141.08, 139.89,
3
1
1
36.83, 131.36, 128.75 (2C), 128.71 (2C), 127.28, 127.15 (3C), 124.94, 123.85, 121.30,
15.96, 109.14, 35.29.
4
.3.3. Synthesis of 2-phenyl-4-(thiophen-2-yl)-5H-indeno[1,2-b]pyridine (10)
1
7

1
The same procedure described in section 4.3 was employed with 3 (R =c) (0.94 g, 4 mmol),
anhydrous ammonium acetate (3.17 g, 40 mmol), 4 (3.17 g, 7 mmol) and glacial acetic acid
(
10 mL) to yield 311 mg (0.95 mmol, 23.9 %) as a yellow solid.
o
TLC (ethyl acetate / n-hexane = 1:10) R = 0.31, mp: 148.6-151.5 C, HPLC: Retention time:
f
+
1
2.59 min, purity: 95.8%; ESI LC/MS (condition A): m/z calcd for C H NS [MH] 326.10;
2
2
15
found 326.33
1
H NMR (250 MHz, CDCl ) δ 8.20 (dd, J = 6.39, 1.86 Hz, 1H, indenopyridine H-9), 8.12-
3
8
.09 (m, 2H, 2-phenyl H-2, H-6), 7.86 (s, 1H, indenopyridine H-3), 7.67 (dd, J = 3.69, 0.9 Hz,
H, 4-thiophene H-5), 7.61 (dd, J = 7.06, 1.12 Hz, 1H, 4-thiophene H-3), 7.51-7.42 (m, 6H,
-phenyl H-3, H-4, H-5, indenopyridine H-6, H-7, H-8), 7.22 (dd, J = 5.1, 3.8 Hz, 1H, 4-
1
2
thiophene H-4), 4.13 (s, 2H, indenopyridine H-5).
1
3
C NMR (62.5 MHz, CDCl ) δ 161.71, 157.11, 143.77, 140.95, 139.75, 138.46, 130.77,
3
1
3
28.84, 128.81, 128.72 (3C), 128.04, 127.27, 127.16 (3C), 126.84, 124.93, 121.36, 115.92,
5.65.
4
.3.4. Synthesis of 2-phenyl-4-(thiophen-3-yl)-5H-indeno[1,2-b]pyridine (11)
1
The same procedure described in section 4.3 was employed with 3 (R =d) (1.58 g, 7 mmol),
anhydrous ammonium acetate (5.56 g, 70 mmol), 4 (2.27 g, 7 mmol) and glacial acetic acid
(
12 mL) to yield 686 mg (2.11 mmol, 30.1%) as a yellow solid.
o
TLC (ethyl acetate / n-hexane = 1:15) R = 0.29, mp: 159.5-160.3 C, HPLC: Retention time:
f
+
1
1.38 min, purity: 96.9%; ESI LC/MS (condition A): m/z calcd for C H NS [MH] 326.10;
2
2
15
found 326.34
1
8

1
H NMR (250 MHz, CDCl ) δ 8.2 (dd, J = 7.27, 1.38 Hz, 1H, indenopyridine H-9), 8.12-
3
8
1
.09 (m, 2H, 2-phenyl H-2, H-6), 7.78 (s, 1H, indenopyridine H-3), 7.5 (dd, J = 3.7, 1.41 Hz,
H, 4-thiophene H-2), 7.51-7.40 (m, 8H, 2-phenyl H-3, H-4, H-5, indenopyridine H-6, H-7,
H-8, 4-thiophene H-4, H-5), 4.13 (s, 2H, indenopyridine H-5).
1
3
C NMR (62.5 MHz, CDCl ) δ 161.44, 157.15, 143.81, 141.08, 140.30, 139.87, 139.38,
3
1
3
31.87, 128.71 (3C), 127.24, 127.14 (3C), 127.11, 126.44, 124.91, 124.34, 121.32, 117.09,
5.17.
4
.3.5. Synthesis of 2-phenyl-4-(pyridin-2-yl)-5H-indeno[1,2-b]pyridine (12)
1
The same procedure described in section 4.3 was employed with 3 (R =e) (0.88 g, 4 mmol),
anhydrous ammonium acetate (3.17 g, 40 mmol), 4 (1.3 g, 4 mmol) and glacial acetic acid
(
10 mL) to yield 458 mg (1.42 mmol, 35.7 %) as a yellow solid.
o
TLC (ethyl acetate / n-hexane = 1:10) R = 0.16, mp : 160.9-163.1 C, HPLC: Retention time:
f
+
1
3.72 min, purity: 97.8%; ESI LC/MS (condition A): m/z calcd for C H N [MH] 321.14;
2
3
16
2
found 321.35
1
H NMR (250 MHz, CDCl ) δ 8.8 (dt, J = 4.7, 1.11 Hz, 1H, 4-pyridine H-6), 8.28-8.19 (m,
3
3
H, indenopyridine H-9, 2-phenyl H-2, H-6), 8.04 (s, 1H, indenopyridine H-3), 7.87-7.84 (m,
H, 2-phenyl H-3, H-5), 7.6-7.3 (m, 7H, 4-pyridine H-3, H-4, H-5, 2-phenyl H-4,
2
indenopyridine H-6, H-7, H-8), 4.24 (s, 2H, indenopyridine H-5).
1
3
C NMR (62.5 MHz, CDCl ) δ 161.80, 157.16, 156.43, 149.84, 144.63, 143.87, 140.88,
3
1
1
39.84, 136.75, 133.23, 128.73, 128.67 (3C), 127.17, 127.05 (2C), 124.90, 123.20, 122.73,
21.29, 117.04, 35.47.
1
9

4
.3.6. Synthesis of 2-phenyl-4-(pyridin-3-yl)-5H-indeno[1,2-b]pyridine (13)
1
The same procedure described in section 4.3 was employed with 3 (R =f) (0.88 g, 4 mmol),
anhydrous ammonium acetate (3.17 g, 40 mmol), 4 (1.3 g, 4 mmol) and glacial acetic acid (8
mL) to yield 398 mg (1.24 mmol, 31.1 %) as a yellow solid.
o
TLC (ethyl acetate / n-hexane = 1:10) R = 0.21, mp : 157.8-159.2 C, HPLC: Retention time:
f
+
1
3.46 min, purity: 96.3%; ESI LC/MS (condition A): m/z calcd for C H N [MH] 321.14;
2
3
16
2
found 321.35
1
H NMR (250 MHz, CDCl ) δ 9.02 (s, 1H, 4-pyridine H-2), 8.78 (d, J = 4.9 Hz, 1H, 4-
3
pyridine H-6), 8.18-8.14 (m, 3H, indenopyridine H-9, 2-phenyl H-2, H-6), 7.98 (s, 1H,
indenopyridine H-3), 7.86-7.84 (m, 2H, 2-phenyl H-3, H-5), 7.66-7.28 (m, 6H, 4-pyridine H-
4
, H-5, 2-phenyl H-4, indenopyridine H-6, H-7, H-8), 4.22 (s, 2H, indenopyridine H-5).
1
3
C NMR (62.5 MHz, CDCl ) δ 161.24, 159.44, 157.16, 150.34, 149.84, 145.63, 143.87,
3
1
1
41.68, 136.70, 132.22, 129.32, 128.73 (2C), 128.37, 127.57 (2C), 127.12, 124.88, 123.32,
22.65, 121.11, 117.24, 35.36.
4
.3.7. Synthesis of 2-phenyl-4-(pyridin-4-yl)-5H-indeno[1,2-b]pyridine (14)
1
The same procedure described in section 4.3 was employed with 3 (R =g) (0.88 g, 4 mmol),
anhydrous ammonium acetate (3.17 g, 40 mmol), 4 (1.3 g, 4 mmol) and glacial acetic acid
(10 mL) to yield 356 mg (1.11 mmol, 27.8 %) as a light yellow solid.
o
TLC (ethyl acetate / n-hexane = 1: 10) R = 0.28, mp : 162.5-164.2 C, HPLC: Retention
f
+
time: 14.92 min, purity: 95.9%; ESI LC/MS (condition A): m/z calcd for C H N [MH]
2
3
16
2
3
21.14; found 321.35
2
0

1
H NMR (250 MHz, CDCl ) δ 8.74 (br, 2H, 4-pyridine H-2, H-6), 8.16-8.06 (m, 3H,
3
indenopyridine H-9, 2-phenyl H-2, H-6), 7.93-7.84 (m, 3H, indenopyridine H-3, 4-pyridine
H-3, H-5), 7.68-7.42 (m, 6H, indenopyridine H-6, H-7, H-8, 2-pheny H-3, H-4, H-5), 4.19 (s,
2
H, indenopyridine H-5).
1
3
C NMR (62.5 MHz, CDCl ) δ 161.34, 159.46, 157.13, 151.02, 146.23, 143.87, 141.32,
3
1
1
36.42, 132.22, 129.44 (2C), 128.71, 128.46, 127.21, 127.12 (2C), 124.88, 123.32, 122.35,
21.61, 117.10, 116.23, 35.63.
4
.3.8. Synthesis of 2-(4-(Furan-2-yl)-5H-indeno [1, 2-b] pyridin-2-yl) phenol (15)
1
The same procedure described in section 4.3 was employed with 3 (R =a) (1.05 g, 5 mmol),
anhydrous ammonium acetate (3.85 g, 50 mmol), 5 (1.71 g, 5 mmol) and methanol (20 mL)
to yield 436 mg (1.32 mmol, 26.7 %) as a light solid.
TLC (ethyl acetate / n-hexane = 1:10) R = 0.23, mp: 211.2-212.9 °C, HPLC: Retention time:
f
+
1
2.75 min, purity: 98.7%; ESI LC/MS (condition A): m/z calcd for C H NO [MH] 326.12;
2
2
15
2
found 326.43
1
H NMR (250 MHz, CDCl ) δ 14.51 (s, 1H, 2-phenyl 2-OH), 8.06 (s, 1H, indenopyridine H-
3
3
), 8.01-7.98 (m, 1H, indenopyridine H-9), 7.91 (dd, J = 7.95, 0.95 Hz, 1H, 2-phenyl H-6),
7
.65 (br, 1H, 4-furan H-5), 7.60-7.57 (m, 1H, indenopyridine H-6), 7.46-7.43 (m, 2H,
indenopyridine H-8, H-7), 7.33 (td, J = 8.27, 1.3 Hz, 1H, 2-phenyl H-4), 7.06 (d, J = 8 Hz,
H, 2-phenyl H-3), 6.98 (d, J = 3.47 Hz, 1H, 4-furan H-3), 6.92 (t, J = 7.77 Hz, 1H, 2-phenyl
H-5), 6.62-6.60 (m, 1H, 4-furan H-4), 4.02 (s, 2H, indenopyridine H-5).
1
1
3
C NMR (62.5 MHz, CDCl ) δ 159.94, 158.09, 156.89, 150.98, 144.01, 143.98, 139.18,
3
2
1

1
35.26, 131.12, 129.31, 128.87, 127.41, 126.43, 125.06, 120.89, 119.44, 118.80, 118.55,
112.30, 111.45, 111.22, 35.69.
4
.3.9. Synthesis of 2-(4-(Furan-3-yl)-5H-indeno[1, 2-b]pyridin-2-yl)phenol (16)
1
The same procedure described in section 4.3 was employed with 3 (R =b) (1.05 g, 5 mmol),
anhydrous ammonium acetate (3.85 g, 50 mmol), 5 (1.71 g, 5 mmol) and methanol (20 mL)
at 100°C for 24 h to yield 574 mg (1.76 mmol, 35.4 %) as a dark brown solid.
TLC (ethyl acetate / n-hexane = 1:10) R = 0.21, mp: 196.0-197.4 °C, HPLC: Retention time:
f
+
1
1.51 min, purity: 96.4%; ESI LC/MS (condition A): m/z calcd for C H NO [MH] 326.12;
2
2
15
2
found 326.42
1
H NMR (250 MHz, CDCl ) δ 14.48 ( s, 1H, 2-phenyl 2-OH), 8.02-7.98 (m, 2H,
3
indenopyridine H-9, H-3), 7.87 (dd, J = 8.02, 1.3 Hz, 1H, 2-phenyl H-6), 7.82 (s, 1H, 4-furan
H-2), 7.61-7.56 (m, 2H, indenopyridine H-6, 4-furan H-5), 7.49-7.41 (m, 2H, indenopyridine
H-8, H-7), 7.32 (td, J = 8.25, 1.57 Hz, 1H, 2-phenyl H-4), 7.08 (dd, J = 8.17, 0.8 Hz, 1H, 2-
phenyl H-3), 6.96-6.89 (m, 2H, 2-phenyl H-5, 4-furan H-4), 3.91 (s, 2H, indenopyridine H-5).
1
3
C NMR (62.5 MHz, CDCl ) δ 159.94, 157.85, 156.97, 144.05, 143.63, 141.79, 139.33,
3
1
38.23, 131.16 (2C), 129.32, 127.53, 126.30, 125.09, 123.60, 120.96, 119.37, 118.80, 118.59,
114.13, 109.08, 35.44.
4
.3.10. Synthesis of 2-(4-(Thiophen-2-yl)-5H-indeno[1,2-b]pyridin-2-yl)phenol (17)
1
The same procedure described in section 4.3 was employed with 3 (R =c) (1.13 g, 5 mmol),
dry ammonium acetate (3.85 g, 50 mmol), 5 (1.71 g, 5 mmol) and methanol (20 mL) at
2
2

1
00°C for 24 h to yield 568 mg (1.66 mmol, 35.2 %) as a grey solid.
TLC (ethyl acetate / n-hexane = 1:10) R =0.26, mp: 243.2-244.8 °C, HPLC: Retention time:
f
+
1
3
1
3.39 min, purity: 97.2%; ESI LC/MS (condition B): m/z calcd for C H NOS [MH]
22 15
42.10; found 342.43
H NMR (250 MHz, CDCl ) δ 14.50 (s, 1H, 2-phenyl 2-OH), 8.01-7.98 (m, 1H,
3
indenopyridine H-9), 7.95 (s, 1H, indenopyridine H-3), 7.85 (dd, J = 8.01, 1.47 Hz, 1H, 2-
phenyl H-6), 7.64 (dd, J = 3.7, 1.07 Hz, 1H, 4-thiophene H-3), 7.59-7.56 (m, 1H,
indenopyridine H-6), 7.53 (dd, J = 5.07, 1.05 Hz, 1H, 4-thiophene H-5) 7.46-7.43 (m, 2H,
indenopyridine H-8, H-7), 7.32 (td, J = 8.6, 1.17 Hz, 1H, 2-phenyl H-4), 7.22 (t, J = 5.1 Hz,
1
H, 4-thiophene H-4), 7.04 (dd, J = 8.25, 1.17 Hz, 1H, 2-phenyl H-3), 6.93 (td, J = 7.22, 1.27
Hz, 1H, 2-phenyl H-5), 4.04 (s, 2H, indenopyridine H-5).
1
3
C NMR (62.5 MHz, CDCl ) δ 159.88, 158.19, 156.84, 143.82, 140.27, 139.63, 139.14,
3
1
31.19, 130.50, 129.38, 128.17, 127.79, 127.47, 127.41, 126.32, 125.05, 120.97, 119.24,
118.83, 118.55, 114.02, 35.81.
4
.3.11. Synthesis of 2-(4-(Thiophen-3-yl)-5H-indeno[1,2-b]pyridin-2-yl)phenol (18)
1
The same procedure described in section 4.3 was employed with 3 (R =d) (1.13 g, 5 mmol),
anhydrous ammonium acetate (3.85 g, 50 mmol), 5 (2.05 g, 6 mmol) and methanol (20 mL)
at 100°C for 24 h to yield 875 mg (2.56 mmol, 51.3 %) as a yellow solid.
TLC (ethyl acetate / n-hexane = 1:10) R = 0.24, mp: 231.3-232.7 °C, HPLC: Retention time:
f
+
1
2.75 min, purity: 97.4%; ESI LC/MS (condition C): m/z calcd for C H NOS [MH]
22 15
2
3

3
42.10; found 342.43
1
H NMR (250 MHz, CDCl ) δ 14.52 (s, 1H, 2-phenyl 2-OH), 8.0-7.97 (m, 1H,
3
indenopyridine H-9), 7.86 (s, 1H, indenopyridine H-3), 7.82 (s, 1H, 4-thiophene H-2), 7.72-
7
.71 (m, 1H, 2-phenyl H-6), 7.54 (d, J = 5.45 Hz, 1H, 4-thiophene H-4), 7.52-7.50 (m, 1H,
indenopyridine H-6), 7.49 (d, J = 2.6 Hz, 1H, 4-thiophene H-5), 7.44-7.41 (m, 2H,
indenopyridine H-8, H-7), 7.3 (t, J = 8.15 Hz, 1H, 2-phenyl H-4), 7.06 (d, J = 8.15 Hz, 1H, 2-
phenyl H-3), 6.9 (t , J = 7.25 Hz, 1H, 2-phenyl H-5), 3.96 (s, 2H, indenopyridine H-5).
1
3
C NMR (62.5 MHz, CDCl ) δ 159.93, 157.94, 156.99, 143.89, 141.55, 139.31, 138.90,
3
1
31.68, 131.12, 129.26, 127.45, 127.01, 126.68, 126.32, 125.04, 124.94, 120.95, 119.39,
118.79, 118.56, 115.29, 35.33.
4
.3.12. Synthesis of 2-(4-(Pyridin-2-yl)-5H-indeno[1,2-b]pyridin-2-yl)phenol (19)
1
The same procedure described in section 4.3 was employed with 3 (R =e) (0.66 g, 3 mmol),
anhydrous ammonium acetate (2.31 g, 30 mmol), 5 (1.535 g, 4.5 mmol) and methanol (12
mL) at 95-100 °C for 24 h to yield 502 mg (1.72 mmol, 58.2 %) as a yellow solid.
TLC (ethyl acetate / n-hexane =1:10) R = 0.13, mp: 223.3-224.6 °C, HPLC: Retention time:
f
+
1
1.36 min, purity: 95.6%; ESI LC/MS (condition A): m/z calcd for C H N O [MH] 337.13;
2
3
16
2
found 337.45
1
H NMR (250 MHz, DMSO-d ) δ 13.99 (s, 1H, 2-phenyl 2-OH), 8.85 (br, 1H, 4-pyridine H-
6
6
), 8.52 (s, 1H, indenopyridine H-3), 8.31 (d, J = 7.75 Hz, 1H, 2-phenyl H-6), 8.24 (d, J =
7
.82 Hz, 1H, indenopyridine H-9), 8.08-7.97 (m, 2H, 4-pyridine H-3, H-4), 7.76-7.74 (m, 1H,
indenopyridine H-6), 7.58-7.53 (m, 3H, indenopyridine H-8, H-7, 4-pyridine H-5), 7.35 (t, J
2
4

=
8.25 Hz, 1H, 2-phenyl H-4), 7.01-6.94 (m, 2H, 2-phenyl H-3, H-5), 4.39 (s, 2H,
indenopyridine H-5).
1
3
C NMR (62.5 MHz, DMSO-d ) δ 159.70, 158.69, 157.18, 155.55, 150.64, 145.92, 145.75,
6
1
1
39.25, 138.34, 134.13, 132.11, 130.46, 128.53, 128.32, 126.54, 125.07, 124.49, 120.98,
20.46, 119.97, 118.76, 117.03, 36.64.
4
.3.13. Synthesis of 2-(4-(Pyridin-3-yl)-5H-indeno[1,2-b]pyridin-2-yl)phenol (20)
1
The same procedure described in section 4.3 was employed with 3 (R =f) (0.66 g, 3 mmol),
anhydrous ammonium acetate (2.31 g, 30 mmol), 5 (1.54 g, 4.5 mmol) and methanol (15 mL)
at 95-100 °C for 24 h to yield 432 mg (1.29 mmol, 42.3 %) as a light brown solid.
TLC (ethyl acetate / n-hexane = 1:2) R = 0.18, mp: 222.3-224.7 °C, HPLC: Retention time:
f
+
8
.31 min, purity: 97.9%; ESI LC/MS (condition A): m/z calcd for C H N O [MH] 337.13;
2
3
16
2
found 337.46
1
H NMR (250 MHz, CDCl ) δ 14.43 (s, 1H, 2-phenyl 2-OH), 8.94 (br, 1H, 4-pyridine H-2),
3
8
.76 (br, 1H, 4-pyridine H-6), 8.10-8.07 (m, 1H, indenopyridine H-9), 7.97 (d, J = 7.75 Hz,
1
H, 4-pyridine H-4), 7.90 (br, 1H, 2-phenyl H-6), 7.81 (s, 1H, indenopyridine H-3), 7.60-7.46
(
m, 4H, indenopyridine H-6, H-8, H-7, 4-pyridine H-5), 7.33 (td, J = 8.25, 1.42 Hz, 1H, 2-
phenyl H-4), 7.09 (d, J = 8.25 Hz, 1H, 2-phenyl H-3), 6.93 (t, J = 7.87 Hz, 1H, 2-phenyl H-5),
4
.0 (s, 2H, indenopyridine H-5).
1
3
C NMR (62.5 MHz, CDCl ) δ 160.39, 158.64, 157.93, 150.61, 149.51, 144.80, 144.47,
3
1
39.65, 136.02, 133.21, 131.96 (2C), 130.11, 128.17, 126.64, 125.73, 121.71, 119.65, 119.49,
119.16, 116.85 (2C), 34.91.
2
5

4
.3.14. Synthesis of 2-(4-(Pyridin-4-yl)-5H-indeno[1,2-b]pyridin-2-yl)phenol (21)
1
The same procedure described in section 4.3 was employed with 3 (R =g) (0.66 g, 3 mmol),
anhydrous ammonium acetate (2.31 g, 30 mmol), 5 (1.54 g, 4.5 mmol) and methanol (15 mL)
at 95-100°C for 24 h to yield 672 mg (1.98 mmol, 66.6 %) as a light yellow solid.
TLC (ethyl acetate / n-hexane = 1:1) R =0.25, mp: 251.2-252.3 °C, HPLC: Retention time:
f
+
8
.43 min, purity: 97.7%; ESI LC/MS (condition A): m/z calcd for C H N O [MH] 337.13;
2
3
16
2
found 337.45
1
H NMR (250 MHz, DMSO-d ) δ 13.84 (s, 1H, 2-phenyl 2-OH), 8.79 (br, 2H, 4-pyridine H-
6
2
, H-6), 8.22 (br, 2H, indenopyridine H-3, H-9), 7.99-7.91 (m, 3H, 2-phenyl H-6, 4-pyridine
H-3, H-5), 7.70 (br, 1H, indenopyridine H-6), 7.56-7.53 (m, 2H, indenopyridine H-8, H-7),
7
.34 (t, J = 7.7 Hz, 1H, 2-phenyl H-4), 7.0-6.92 (m, 2H, 2-phenyl H-3, H-5), 4.22 (s, 2H,
indenopyridine H-5).
1
3
C NMR (62.5 MHz, DMSO-d ) δ 158.94, 157.23, 156.68, 150.43 (3C), 145.08, 144.82
6
(
2C), 138.61, 133.35, 131.51, 129.87, 128.07, 127.74, 125.86, 123.39, 120.42, 119.70, 119.27,
18.02, 117.26, 34.30.
1
4
.3.15. Synthesis of 3-(4-(Furan-2-yl)-5H-indeno[1, 2-b]pyridin-2-yl)phenol (22)
1
The same procedure described in section 4.3 was employed with 3 (R =a) (1.05 g, 5 mmol),
anhydrous ammonium acetate (3.85 g, 50 mmol), 6 (1.71 g, 5 mmol) and methanol (20 mL)
at 100°C for 48 h to yield 834 mg (2.58 mmol, 51.3 %) as a light yellow solid.
TLC (ethyl acetate / n-hexane = 1:3) R = 0.26, mp: 228.2-229.4 °C, HPLC: Retention time:
f
2
6

+
9
.80 min, purity: 99.8%; ESI LC/MS (condition A): m/z calcd for C H NO [MH] 326.12;
22 15 2
found 326.43
1
H NMR (250 MHz, CDCl ) δ 8.23 (dd, J = 6.02, 2.57 Hz, 1H, indenopyridine H-9), 7.96 (s,
3
1
H, indenopyridine H-3), 7.81 (d, J = 1.42 Hz, 1H, 2-phenyl H-6), 7.67-7.62 (m, 3H, 2-
phenyl H-2, indenopyridine H-6, 4-furan H-5), 7.47-7.43 (m, 2H, indenopyridine H-8, H-7),
7
1
.38 (t, J = 7.85 Hz, 1H, 2-phenyl H-5), 7.02 (d, J = 3.45 Hz, 1H, 4-furan H-3), 6.93-6.89 (m,
H, 2-phenyl H-4), 6.65- 6.63 (m, 1H, 4-furan H-4), 4.12 (s, 2H, indenopyridine H-5).
1
3
C NMR (62.5 MHz, CDCl ) δ 161.58, 156.82, 156.45, 151.54, 144.01, 143.70, 141.36,
3
1
40.67, 134.49, 129.92, 129.56, 128.90, 127.32, 124.94, 121.39, 119.38, 116.10, 114.52,
113.53, 112.17, 110.76, 35.42.
4
.3.16. Synthesis of 3-(4-(Furan-3-yl)-5H-indeno[1, 2-b]pyridin-2-yl)phenol (23)
1
The same procedure described in section 4.3 was employed with 3 (R =b) (1.05 g, 5 mmol),
anhydrous ammonium acetate (3.85 g, 50 mmol), 6 (1.71 g, 5 mmol) and methanol (20 mL)
at 100°C for 24 h to yield 724 mg (2.22 mmol, 44.6 %) as a light yellow solid.
TLC (ethyl acetate / n-hexane = 1:10) R = 0.26, mp: 231.4-232.1 °C, HPLC: Retention time:
f
+
8
.17 min, purity: 98.5%; ESI LC/MS (condition A): m/z calcd for C H NO [MH] 326.12;
2
2
15
2
found 326.42
1
H NMR (250 MHz, DMSO-d ) δ 9.58 ( s, 1H, 2-phenyl 3-OH), 8.53 (s, 1H, 4-furan H-2),
6
8
.07-8.06 (m, 1H, indenopyridine H-9), 7.99 (s, 1H, indenopyridine H-3), 7.93-7.91 (m, 1H,
-furan H-5), 7.73-7.68 (m, 3H, 2-phenyl H-2, H-6, indenopyridine H-6), 7.51-7.47 (m, 2H,
4
indenopyridine H-8, H-7), 7.38 (d, J = 1.17 Hz, 1H, 4-furan H-4), 7.32 (t, J = 7.9 Hz, 1H, 2-
2
7

phenyl H-5), 6.86 (dd, J = 7.87, 1.6 Hz, 1H, 2-phenyl H-4), 4.15 (s, 2H, indenopyridine H-5).
1
3
C NMR (62.5 MHz, DMSO-d ) δ 160.44, 157.93, 156.0, 144.62, 144.33, 143.11, 140.61
6
(
2C), 137.08, 131.69, 129.83, 129.07, 127.41, 125.59, 123.42, 120.62, 117.93, 116.13, 115.70,
13.93, 109.76, 35.76.
1
4
.3.17. Synthesis of 3-(4-(Thiophen-2-yl)-5H-indeno[1,2-b]pyridin-2-yl)phenol (24)
1
The same procedure described in section 4.3 was employed with 3 (R =c) (0.68 g, 3 mmol),
anhydrous ammonium acetate (2.31 g, 30 mmol), 6 (1.54 g, 4.5 mmol) and methanol (12 mL)
at 100 °C for 36 h to yield 606 mg (1.77 mmol, 59.1 %) as a yellow solid.
TLC (ethyl acetate / n-hexane = 1:3) R = 0.28, mp: 227.9-229.1 °C, HPLC: Retention time:
f
+
1
3
1
0.75 min, purity: 98.5%; ESI LC/MS (condition A): m/z calcd for C H NOS [MH]
22 15
42.10; found 342.44
H NMR (250 MHz, DMSO-d ) δ 9.56 (s, 1H, 2-phenyl 3-OH), 8.09-8.05 (m, 1H,
6
indenopyridine H-9), 8.03 (d, J = 3.72 Hz, 1H, 4-thiophene H-3), 8.0 (s, 1H, indenopyridine
H-3), 7.87 (d, J = 5.0 Hz, 1H, 4-thiophene H-5), 7.74-7.65 (m, 3H, 2-phenyl H-2, H-6
indenopyridine H-6), 7.52-7.49 (m, 2H, indenopyridine H-8, H-7), 7.36-7.30 (m, 2H, 4-
thiophene H-4, 2-phenyl H-5), 6.88 (dd, J = 7.87, 1.12 Hz, 1H, 2-phenyl H-4), 4.23 (s, 2H,
indenopyridine H-5).
1
3
C NMR (62.5 MHz, DMSO-d ) δ 161.45, 158.56, 156.75, 144.90, 140.97, 140.50, 139.04,
6
1
31.43, 130.50, 129.81, 129.45, 129.29 (2C), 129.02, 128.06, 126.06, 120.04, 118.43, 116.86,
115.78, 114.46, 36.03.
2
8

4
.3.18. Synthesis of 3-(4-(Thiophen-3-yl)-5H-indeno[1,2-b]pyridin-2-yl)phenol (25)
1
The same procedure described in section 4.3 was employed with 3 (R =d) (1.13 g, 5 mmol),
anhydrous ammonium acetate (3.85 g, 50 mmol), 6 (3.41 g, 10 mmol) and glacial acetic acid
(
10 mL) at 100°C for 24 h to yield 1.120 g (3.28 mmol, 65.6 %) as a yellow solid.
TLC (ethyl acetate / n-hexane = 1:3) R = 0.27, mp: 244.0-245.0 °C, HPLC: Retention time:
f
+
9
.74 min, purity: 95.9%; ESI LC/MS (condition A): m/z calcd for C H NOS [MH] 342.10;
2
2
15
found 342.42
1
H NMR (250 MHz, DMSO-d ) δ 9.51 ( s, 1H, 2-phenyl 3-OH), 8.29 (s, 1H, 4-thiophene H-
6
2
), 8.09-8.05 (m, 1H, indenopyridine H-9), 7.98 (s, 1H, indenopyridine H-3), 7.87-7.85 (m,
H, 4-thiophene H-4), 7.79-7.76 (m, 1H, 4-thiophene H-5), 7.72-7.67 (m, 3H, 2-phenyl H-2,
1
H-6, indenopyridine H-6), 7.5-7.48 (m, 2H, indenopyridine H-8, H-7), 7.32 (t, J = 7.87 Hz,
H, 2-phenyl H-5), 6.86 (dd, J = 7.9, 1.6 Hz, 1H, 2-phenyl H-4), 4.22 (s, 2H, indenopyridine
H-5).
1
1
3
C NMR (62.5 MHz, DMSO-d ) δ 161.27, 158.52, 156.72, 145.06, 141.22, 141.19, 140.79,
6
1
39.35, 132.67, 130.40, 129.60, 128.38, 127.95, 127.88, 126.76, 126.15, 121.21, 118.50,
117.28, 116.72, 114.53, 35.64.
4
.3.19. Synthesis of 3-(4-(Pyridin-2-yl)-5H-indeno[1,2-b]pyridin-2-yl)phenol (26)
1
The same procedure described in section 4.3 was employed with 3 (R =e) (0.66 g, 3 mmol),
anhydrous ammonium acetate (2.31 g, 30 mmol), 6 (1.56 g, 4.5 mmol) and methanol (12 mL)
at 95-100 °C for 24 h to yield 558 mg (1.66 mmol, 55.3 %) as a yellow solid.
TLC (ethyl acetate / n-hexane = 1:2) R = 0.24, mp: 202.1-203.9 °C, HPLC: Retention time:
f
2
9