Synthesis and biological activity of 2,4-di-p-phenolyl-6-2-furanyl-pyridine as a potent topoisomerase II poison

Article abstract of DOI:10.1016/j.ejmech.2014.11.045

Dihydroxylated 2,4-diphenyl-6-aryl pyridine derivatives were simply achieved using Claisen-Schmidt condensation reaction and modified Kr?hnke pyridine synthetic method. Total forty-five compounds were designed and synthesized which contain hydroxyl groups

Full text of DOI:10.1016/j.ejmech.2014.11.045

Accepted Manuscript
Synthesis and Biological Activity of 2,4-Di-p-Phenolyl-6-2-Furanyl-Pyridine As a
Potent Topoisomerase II Poison
Radha Karki , Chanmi Park , Kyu-Yeon Jun , Tata Man Kadayatt , Eung-Seok Lee ,
Youngjoo Kwon
PII:
S0223-5234(14)01077-0
10.1016/j.ejmech.2014.11.045
EJMECH 7538
DOI:
Reference:
To appear in: European Journal of Medicinal Chemistry
Received Date: 11 July 2014
Revised Date: 29 September 2014
Accepted Date: 23 November 2014
Please cite this article as: R. Karki, C. Park, K.-Y. Jun, T.M. Kadayatt, E.-S. Lee, Y. Kwon, Synthesis
and Biological Activity of 2,4-Di-p-Phenolyl-6-2-Furanyl-Pyridine As a Potent Topoisomerase II Poison,
European Journal of Medicinal Chemistry (2014), doi: 10.1016/j.ejmech.2014.11.045.
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ACCEPTED MANUSCRIPT
Graphical Abstract
Synthesis and Biological Activity of 2,4-Di-p-Phenolyl-6-2-Furanyl-Pyridine As a Potent
Topoisomerase II Poison
#[a]
#[b]
[b]
[a]
[a]
Radha Karki, Chanmi Park,
Kyu-Yeon Jun, Tata Man Kadayatt, Eung-Seok Lee,* and Youngjoo
[
b]
Kwon*
[a]
College of Pharmacy, Yeungnam University, Gyeongsan 712-749 (Republic of Korea)
[b]
College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Global Top 5 program Ewha
Womans University, Seoul 120-750 (Republic of Korea)

ACCEPTED MANUSCRIPT
Synthesis and Biological Activity of 2,4-Di-p-Phenolyl-6-2-Furanyl-Pyridine As a Potent
Topoisomerase II Poison
#
[a]
#[b]
[b]
[a]
[a]
Radha Karki, Chanmi Park,
Kyu-Yeon Jun, Tata Man Kadayatt, Eung-Seok Lee,*
[
b]
and Youngjoo Kwon*
[a]
College of Pharmacy, Yeungnam University, Gyeongsan 712-749 (Republic of Korea)
[b]
College of Pharmacy, Graduate School of Pharmaceutical Sciences, Ewha Global Top 5
program Ewha Womans University, Seoul 120-750 (Republic of Korea)
#
Authors are equal contributors
Corresponding Authors:
*
Tel: +82 53 810-2827, fax: +82 53 810-4654, email: eslee@ynu.ac.kr (E.-S.L.)
Tel: +82 2 3277-4653, fax: +82 2 3277-2851, email: ykwon@ewha.ac.kr (Y.K.)

ACCEPTED MANUSCRIPT
Abstract
Dihydroxylated 2,4-diphenyl-6-aryl pyridine derivatives were simply achieved using Claisen-
Schmidt condensation reaction and modified Kröhnke pyridine synthetic method. Total forty-
five compounds were designed and synthesized which contain hydroxyl groups at ortho, meta
or para position of 2- and 4-phenyl rings attached to the central pyridine. They were
evaluated for topoisomerase I and II inhibitory activity, and cytotoxicity against several
human cancer cell lines for the development of novel antitumor agents. Most of the prepared
compounds exhibited significant antiproliferative activity on human cancer cell lines, HCT15
and K562, as well as potent topo II inhibitory activity comparable to or stronger than
etoposide. The structure-activity relationship demonstrated that compounds with hydroxyl
group at meta or para position of 2-phenyl ring in combination with hydroxyl at ortho, meta
or para position of 4-phenyl ring displayed the most potent topoisomerase II inhibitory
activity and cytotoxicity. Positive correlation between topoisomerase II inhibition and
cytotoxicity was obtained for several compounds (30, 35, 36, 40-45, 49, 54, 56). Compound
56 showed the most potent topoisomerase II inhibitory activity at low concentration and
functioned as a topoisomerase poison like the mode of action of etoposide.
Keywords: Terpyridine bioisosteres; Topoisomerase poison; Antitumor agents;
Dihydroxylated 2,4-diphenyl-6-aryl pyridine; Cytotoxicity

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1
. Introduction
DNA topoisomerases, the molecular targets of many antimicrobial and anticancer agents,
have an important role in cell proliferation and differentiation [1]. They are involved in all
events related to DNA metabolism including replication, transcription, recombination, repair,
chromatin assembly and chromosome segregation [1-3]. DNA topoisomerases are basically
classified into two types; topoisomerase I (topo I ) and topoisomerase II (topo II). They can
change the topological state of DNA through the breaking and rejoining of DNA strands.
Their catalytic cycle include DNA strand breakage (one strand by topo I or both strand by
topo II), formation of a covalent complex with DNA, followed by DNA strand passage, and
the final religation step of the initial DNA strand [4]. Several topoisomerase inhibitors such
as camptothecin, doxorubicin, etoposide etc are widely used as active anticancer agents [5,6].
Due to severe side effects associated with currently available anticancer agents, extensive
research is going on for the development of new derivatives and novel compounds with
improved therapeutic efficacy and minimizing the toxicities [5-10]. Several naturally
occurring biologically active polyphenolic compounds are reported to possess antioxidant,
antiinflammatory, and anticancer activity [11,12]. Therefore they are viewed as an important
pharmacophore in the medicinal chemistry or drug discovery area. Resveratrol, curcumin,
epigallocatechin gallate etc are few polyphenolic phytochemicals that are well studied for
their antioxidant and anticancer activity [13-16]. Similarly, some flavonoids are reported to
interfere with human topoisomerases. It is observed that hydroxyl moiety present in the
flavonoids have important role for the topoisomerase inhibitory acitivity [17-20]. Several
other studies of synthetic compounds support that introduction of hydroxyl group enhances
topoisomerase inhibitory activity [21-23]. Many clinically used topoisomerase inhibitors such
as camptothecin, doxorubicin and etoposide also contain hydroxyl moieties in their structure.

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All these promising reports on the importance of hydroxyl moiety and our previous results
[
24,25] motivated us to synthesize more compounds with hydroxyl groups. Our study is
aimed at designing and synthesizing topoisomerase-targeting anticancer agents. As a part of
the study, we have previously designed, synthesized and reported several 2,4,6-triaryl
pyridine derivatives as bioisosteres of terpyridine for the topoisomerase inhibitory activity
and cytotoxicity against several human cancer cell lines [26-34]. Furthermore, we have
introduced hydroxyl group(s) [24,25] into phenyl moiety to improve topo I and/or II
inhibitory activities, and cytotoxicity against several human cancer cell lines. In addition,
positive correlation between substituted position of the hydroxyl moiety, topo II inhibition
and cytotoxicity has been observed. Recently reported dihydroxylated 2,4,6-triphenyl
pyridines also displayed significant topo II inhibitory activity, and cytotoxicity [25]. As an
extension to this work, herein we designed and synthesized dihydroxylated 2,4-diphenyl-6-
aryl pyridine derivatives possessing various aryl groups on 6-position of central pyridine as
shown in Figure 1.
(Figure 1)
In this article, we present the synthesis and biological studies of novel dihydroxylated 2,4-
diphenyl-6-aryl pyridine compounds. The bioevaluation of these compounds against topo I
and II was carried out. Further, the ability of these compounds to inhibit proliferation of
various human cancer cell lines were examined and structure-activity relationship (SAR)
according to the number and position of hydroxyl group was established.

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2
. Chemistry
Dihydroxylated 2,4-diphenyl-6-aryl pyridine derivatives 15-59 were synthesized in three
steps as illustrated in Scheme 1. The first step involves the synthesis of various
dihydroxylated propenone intermediates (3, 4 and 5), using Claisen-Schmidt condensation
reaction [35-37]. Total nine compounds were synthesized in 36-90% yield that were reported
3
previously [24,25]. In the second step, five pyridinium iodide salts 6 (R = d-h) were
1
synthesized in quantitative yield by the treatment of aryl ketone 1 (R = d-h) with iodine in
1
2
pyridine. Using modified Kröhnke pyridine synthesis [38,39], final compounds 7 (R = a, R
3
1
2
3
1
2
3
=
a-c, R = d-h), 8 (R = b, R = a-c, R = d-h) and 9 (R = c, R = a-c, R = d-h) were
synthesized by the reaction of appropriate dihydroxylated propenone intermediates 3, 4 or 5
with pyridinium iodide salt 6 in the presence of ammonium acetate and glacial acetic acid in
20-94% yield. The compounds shown in Figure 2 are the non-substituted 2,4-diphenyl-6-aryl
pyridines which were reported earlier [28]. All the compounds displayed weak topo II
inhibitory activity as shown in Table 1. In this study the dihydroxylated derivatives of those
compounds were synthesized. The reaction of nine intermediates and five pyridinium iodide
salts gave total forty-five final compounds. The compounds were designed and synthesized in
nine different series as shown in Figure 3. Each series contains five different compounds with
various aryl groups at 6-position of central pyridine. All the prepared compounds contain two
hydroxyl moieties at various positions (ortho, meta or para) of 2- and 4-phenyl ring of central
pyridine. It was previously shown that introduction of hydroxyl moiety increased topo II
inhibitory activity and cytotoxicity. Furthermore, increase in the number of hydroxyl group
enhanced the activity [24,25]. Herein, more dihydroxylated compounds (15-59) with various
aryl groups at 6-position of the central pyridine were synthesized as displayed in Figure 4.

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(
(
(
(
(
Scheme 1)
Figure 2)
Table 1)
Figure 3)
Figure 4)
3
. Results and Discussion
3.1. Biological activity of compounds 15-59
All the synthesized compounds (15-59) were tested for topo I and II inhibitory activity and
cytotoxicity against several human cancer cell lines. Camptothecin and etoposide, well
known topo I and II inhibitors, respectively, were used as positive controls. Figure 5 and 6
respectively illustrate the topo I and II inhibitory activity of synthesized compounds 15-59.
Among the forty-five synthesized dihydroxylated 2,4-diphenyl-6-aryl pyridine compounds,
only compounds 25, 26 and 29 showed considerable topo I inhibitory activity as shown in
Figure 5 and Table 2. Compounds 25 and 26 displayed 59.9% and 44.3% inhibition at 100
µM and 43.0% and 31.7% inhibition at 20 µM, respectively. Compound 29 showed 33.3%
inhibition at 100 µM. It is interesting to note that all three compounds were from Series C,
which contain hydroxyl group at ortho position of 2-phenyl and para position of 4-phenyl
ring on central pyridine. Although a concrete SAR could not be established, it can be
expected that hydroxyl at ortho position of 2-phenyl and para position of 4-phenyl might be
important for topo I inhibitory activity.

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The effect of synthesized compounds on human DNA topo II were observed in the relaxation
assay using supercoiled pBR322 plasmid DNA in the presence of ATP. Figure 6 and Table 3-
5
summarizes the topo II inhibitory activity of the synthesized compounds. Most of the
compounds showed significant inhibitory activity. Compound 54 possessed the highest topo
II inhibition (98.2%) at 100 µM. Compounds 35, 36, 40, 41 and 49 showed more than 80%
inhibition at 100 µM which was higher than the positive control etoposide. Compounds 15,
19, 20, 25, 26, 36, 45, 49, 54 and 56 displayed significant activity at both 100 and 20 µM.
Compound 56 possessed 76.8% and 74.2% inhibition at 100 and 20 µM, respectively. These
results suggest that dihydroxylated 2,4-diphenyl-6-aryl pyridines are selective for topo II
inhibition, as most of the compounds were devoid of topo I inhibitory activity. Compounds
15-19, 20-24 and 25-29 belong to Series A, Series B and Series C, respectively. Compounds
from these three series possess ortho-hydroxyl group on 2-phenyl ring whereas ortho, meta or
para-hydroxyl on 4-phenyl ring of central pyridine. All compounds from Series A (15–19)
possessed significant topo II inhibitory activity, compound 15 being the most potent with
75.5% and 67.3% inhibition at 100 and 20 µM, respectively. Compounds 17-19 also
displayed strong topo II inhibition at 100 µM which was comparable to etoposide.
Compounds 20, 21 and 24 from Series B displayed considerable inhibitory activity.
Compounds 25-29 from Series C showed significant inhibitory activity that was comparable
to etoposide. Compounds 30-34, 35-39 and 40-44 belong to Series D, Series E and Series F,
respectively, which all the compounds from these three series possess meta-hydroxyl group
on 2-phenyl ring whereas ortho, meta or para-hydroxyl on 4-phenyl ring of central pyridine.
Compounds 30, 32 and 33 from Series D possessed significant topo II inhibitory activity.
Similarly, compounds 35 and 36 from Series E displayed potent inhibitory activity (83.9%
and 81.1%) which was higher than etoposide. All compounds 40-44 from Series F exhibited
significant inhibitory activity (72-88%) at 100 µM that was higher than etoposide. Compound

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40 showed the highest inhibition (88.6%) in this series. Compounds 45-49, 50-54 and 55-59
belong to Series G, Series H and Series I, respectively, which all the compounds from these
three series possess para-hydroxyl group on 2-phenyl ring whereas ortho, meta or para-
hydroxyl on 4-phenyl ring of central pyridine. Compounds 45 and 49 from Series G
displayed stronger inhibitory activity than etoposide whereas compounds 46 and 48 showed
considerable activity. Compound 54 from Series H possessed 98.2% and 37.0% topo II
inhibition at 100 and 20 µM, respectively. Compounds 50, 51 and 53 from the same series
possessed considerable activity. Similarly, compound 56 from Series I showed significant
inhibitory activity of 76.8% and 74.2% at 100 and 20 µM, respectively. Compound 55 also
possess significant activity at 100 µM. For the evaluation of cytotoxicity, five different
human cancer cell lines were utilized: HCT15 (human colorectal adenocarcinoma cell line),
K562 (human myeloid leukemic tumor cell line), DU145 (human prostate tumor cell line),
MCF-7 (human breast adenocarcinoma cell line) and HeLa (human cervix tumor cell line).
The inhibitory activity (IC ) is expressed as micromolar concentration as illustrated in Table
50
2-5. The cytotoxicity results indicate that most of the compounds are active against HCT15
and K562 cell lines. Compounds from Series A, Series B and Series C were less cytotoxic
compared to other series. Most of the compounds possessed considerable activity against
HCT15 and K562 but were less cytotoxic (> 30 µM) against DU145, MCF-7 and HeLa.
Compounds 17, 19, 24 and 29 displayed significant cytotoxicity against HCT15 and
compounds 17, 19 and 29 against K562 as compared to adriamycin and etoposide.
Compounds from Series D, Series E and Series F displayed significant cytotoxicity (< 4 µM)
against HCT15 and K562 whereas moderate cytotoxicity against DU145, MCF-7 and HeLa.
Compounds 30, 32, 33, 37 and 42 possessed stronger cytotoxicity than adriamycin and
etoposide against HCT15. Similarly, compounds 30, 31, 40 and 43 displayed potent
cytotoxicity against K562. Compounds 35–37 displayed significant cytotoxicity (< 3 µM)

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against DU145. Most of these compounds displayed moderate cytotoxicity (< 15 µM) against
MCF-7 and HeLa. The most cytotoxic compounds were from Series G, Series H and Series I.
Compounds 45, 46, 48, 53–56 from these three series displayed potent cytotoxicity (< 1 µM)
against HCT15 which is stronger than adriamycin and etoposide. Compound 56 is the most
cytotoxic among all the synthesized compounds against HCT15, with IC value 0.08 µM.
5
0
Similarly, compounds 49, 53–56 possessed significant cytotoxicity (< 2 µM) against K562
compared to adriamycin and etoposide. Also compounds 45, 46 and 48 showed cytotoxicity
comparable to adriamycin against K562. Most of the compounds from these three series
displayed moderate cytotoxicity (< 10 µM) against DU145, MCF-7 and HeLa. Compounds
45, 48, 49, 53 and 54 possessed considerable cytotoxicity (< 3 µM) against HeLa. It is
observed that all the compounds contain hydroxyl moiety at para position on 2-phenyl ring of
central pyridine.
(Figure 5)
(Figure 6)
(Table 2)
(Table 3)
(Table 4)
(Table 5)

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3.2. Structure-activity relationship (SAR) study
It was found that the introduction of hydroxyl moiety is important for topo II inhibitory
activity and cytotoxicity of 2,4-diphenyl-6-aryl pyridine compounds (10–14). The number
and position of hydroxyl group strongly influenced the activities. Monohydroxylated 2,4-
diphenyl-6-aryl pyridine compounds possessed stronger topo II inhibition and cytotoxicity
[
24] compared to non-hydroxylated compounds but less potent than the dihydroxylated
compounds 15-59. Several studies have indicated that introduction of hydroxyl group at
certain position enhances topo II inhibitory activity [24,25]. In this study, the position of
hydroxyl group at the phenyl ring have variable influence on the topoisomerase inhibitory
activity and cytotoxicity. For the clear SAR study, biological activities of evaluated
compounds in accordance to the position of phenyl ring on the central pyridine are explained
in detail.
Substitution at 2-phenyl ring: Most of the compounds (15, 17-20, 25-29) with hydroxyl
substitution at ortho position has shown significant topo II inhibition but are less cytotoxic to
the tested cancer cell lines. Compounds 30, 35, 36, 40-44 having hydroxyl moiety at meta
position displayed stronger topo II inhibition than etoposide, and also possessed significant
cytotoxicity. Similarly, compounds (45, 46, 48, 49, 53-56) with hydroxyl moiety at para
position also possessed moderate to significant topo II inhibition and potent cytotoxicity. So
the favorable order of substitution of hydroxyl group at 2-phenyl ring for the topo II
inhibition and cytotoxicity is meta > para > ortho.
Substitution at 4-phenyl ring: Most of the compounds (15, 17-19, 30, 32, 33, 45, 49) having
ortho hydroxyl moiety at 4-phenyl ring possessed significant topo II inhibition. However, for

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better cytotoxicity meta or para hydroxyl at 2-phenyl ring is necessary in combination with
ortho hydroxyl at 4-phenyl ring. Para hydroxyl substitution seems to be the most favorable
for both topo II inhibition and cytotoxicity. Some compounds (20, 35-37, 54) with meta
hydroxyl moiety at 4-phenyl ring also possess significant topo II inhibition as well as
cytotoxicity. Therefore, the topo II inhibitory activity and cytotoxicity of compound depends
on the combination of hydroxyl moiety at 2- and 4- phenyl ring of central pyridine.
Aryl substitution at 6-position: Five different aryl groups were introduced at 6 position of
central pyridine. The bioactivity of the prepared compounds is not dependent on the aryl
groups. However, all the compounds with 3-thienyl moiety displayed significant topo II
inhibitory activity.
Figure 7A indicates some compounds having significant topo II inhibitory activity and
cytotoxicity. Most of the compounds (35, 36, 40, 41, 43) possessed hydroxyl moiety at meta
position of 2-phenyl ring while some compounds (49, 54, 56) at para position. Similarly,
compounds (40, 41, 43, 56) possessed hydroxyl moiety at para position of 4-phenyl ring and
compounds (35, 36, 54) at meta position. Compound 54 which displayed the highest topo II
inhibition contains para- and meta-hydroxyl substitution at 2- and 4-phenyl ring of central
pyridine respectively. Compound 56 having 76.8% and 74.2% inhibition at 100 and 20 µM
respectively and IC 0.08 µM against HCT15 possessed para hydroxyl substitution at both
5
0
phenyl rings. All the compounds from series F (40-44), which contain meta and para
hydroxyl moiety at 2- and 4-phenyl ring of central pyridine respectively, displayed stronger
topo II inhibitory activity than the positive control etoposide. Taken together, meta or para
substitution at 2-phenyl ring in combination with ortho, meta or para at 4-phenyl ring of

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central pyridine is important for both topo II inhibition and cytotoxicity as shown in Figure
7B which further supports our previous result [25].
(Figure 7)
3.3. Compound 56 functions as a Topo II poison
Compounds 54 and 56 were further evaluated for the determination of their mode of action.
Compound 54 showed the strongest topo II inhibitory activity at treatment of 100 µM among
tested compounds and compound 56 exhibited the strongest topo II inhibitory activites at low
concentration of 20 µM as well as the strongest cytoxicity againt HCT15 cells. First of all we
checked whether compounds could stablize transiently-formed cleavage comlex with
covalent bonding between DNA and topo II. It is well known that topo II poison induces a
truncated DNA by preventing religation through stablilizing the cleavage complex [6,41].
The treatment of compound 56 formed a short linear DNA like etoposide while compound 54
did not as shown in Figure 8A. This clearly reflected compound 56 funtioned as a topo
poison not as a catalytic inhibitor. We subsequently examined whether compounds 54, 56 and
etoposide generated the accumulation of DNA strand breaks in HCT15 cells using comet
assay. The more percentage of DNA in the tail implies more DNA strand breaks [42,43].
Figure 8B and C show that compound 56 (18.7 ± 5.2% at 10 µM and 46.7 ± 5.5% at 20 µM)
induced significant tail at 20 µM treatment which is comparable to the extent induced by
etoposide (43.0 ± 8.4% at 10 µM and 60.7 ± 8.4% at 20 µM). On the other hand, compound
54 did not induce the tail at both treated concentrations as much as compound 56. The result

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is consistent with no linear DNA form observed by compound 54 treatment in Figure 8A.
Therefore, it is clear that compound 56 funtioned as a topo II poison like etoposide.
Compound 56 was further performed for docking study to clearly compare its mode of action
with that of etoposide. Currently there is only one human topo IIα cleavage core bound to
DNA is available in the Protein Data Bank (PDB, PDB ID: 4FM9) [44]. However this
structure was not appropriate for docking inhibitors, since there was no ligand bound.
Therefore the structure of topo IIβ bound to etoposide and DNA (3QX3) was chosen for the
template to generate the homology model of topo IIα [45]. Molecular docking were carried
out for compound 56 with the topo IIα cleavage core bound to DNA (Figure 9). Compound
5
6 is bound to the catalytic core of topo IIα, intercalating into the cleaved bases of the DNA,
which overlaps with etoposide bound to topo IIα. The compound has hydrophobic
interactions with Gly462, Arg487, Gly488, T+1, G+2 on the cleaved strand of DNA and A+4
on the uncleaved strand. There are also π-π stacking interactions between the bases of T+1,
A+4 and the 4-phenyl ring. The hydroxyl groups from 2, 4-phenyl rings form hydrogen
bonds with Leu486/Gly462 and G+5, respectively, indicated with green dot lines in Figure 9.
The site of the substitution of hydroxyl group on each phenyl ring is essential for the
inhibitory activity of topo IIα in compound 56 since it was able to form hydrogen bonds. This
can explain for the difference in the activity of the compounds depending on the hydroxyl
group substitution sites.
(
Figure 8)
Figure 9)
(

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4
. Conclusions
We have synthesized a new series of dihydroxylated 2,4-diphenyl-6-aryl pyridines by
efficient synthetic route and evaluated their topo I and II inhibition, and cytotoxicity. The
activity of 2,4-diphenyl-6-aryl pyridines was strongly influenced by the number and position
of hydroxyl group on the phenyl ring. Most of the compounds displayed significant topo II
inhibition and cytotoxicity. SAR study suggests that introduction of hydroxyl moiety
increased topo II inhibitory activity, and increase in the number of hydroxyl group further
enhanced the activity. Hydroxyl group at meta or para position on 2-phenyl ring in
combination with hydroxyl at ortho, meta or para position on 4-phenyl ring of central
pyridine displayed significant topo II inhibitory activity and cytotoxicity. Compounds were
particularly more cytotoxic to HCT15 and K562. Positive correlation between topo II
inhibition and cytotoxicity was obtained for several compounds (30, 35, 36, 40-45, 49, 54,
56). Especially, compound 56 exhibited etoposide like inhibition by forming stable cleavage
complex. These findings were confirmed by molecular docking study. The further study and
optimization of these compounds may lead to a new potential antitumor agent.
5
. Experimental Section
Compounds used as starting materials and reagents were obtained from Aldrich Chemical Co.,
Junsei or other chemical companies, and utilized 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.

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Since all the compounds prepared contain aromatic ring, they were visualized and detected on
TLC plates with UV light (short wave, long wave or both). NMR spectra were recorded on a
1
13
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
®
ꢀ
L was injected in Waters X- Terra 5 ꢀM reverse-phase C column (4.6 ⅹ250 mm) with a
1
8
gradient elutions of 50% to 100% of B in A for 15 min followed by 100% to 50% of B in A
for 15 min at a flow rate of 1.0 mL/min at 254 nm UV detection, where mobile phase A was
double distilled water with 20 mM ammonium formate (AF) and B was 90% ACN in water
with 20 mM AF. In case of compounds of Series C (25-29) and Series G (45-49) gradient
elutions of 85% to 100% of B in A for 10 min followed by 100% to 85% of B in A for 20
min was performed with the same mobile phase. Purity of compound is described as percent
(%).
®
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 2 ꢀL
®
injection volume on Waters Atlantis T3 reverse-phase C column (2.1ⅹ50 mm, 3 ꢀm). The
1
8
mobile phase consisted of 100% distilled water (A) and 100% ACN (B). A gradient program
was used with a flow rate of 200 ꢀL/min. The initial composition was 10% B and
programmed linearly to 90% B after 5 min and finally 10% B after 10 min. MS ionization
conditions were: Sheath gas flow rate: 70 arb, aux gas flow rate: 20 arb, I spray voltage: 4.5

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KV, capillary temperature 215 °C, column temperature 40 °C, capillary voltage: 21 V, tube
lens offset: 10 V. Retention time was given in minutes.
5.1. General method for the preparation of compounds 3, 4, and 5
Compounds 3, 4, and 5 were synthesized either by KOH/ NaOH or BF -Et O catalyzed
3
2
Claisen-Schmidt condensation reaction.
1
KOH or NaOH catalyzed: To a solution of equimolar amounts of aryl ketone 1 (R = a-c) and
1
aryl aldehyde 2 (R = a-c) in EtOH was added either 50% aqueous solution of KOH or 6 M
aqueous NaOH solution and stirred for 2 to 24 h at 20 °C. The mixture was neutralized with 6
M aqueous HCl solution (pH adjusted to 2). The mixture was extracted with ethyl acetate,
and washed with water and brine. It was further purified by either recrystallization or column
chromatography to yield pure solid compounds.
1
1
BF -Et O catalyzed: To a solution of aryl ketone 1 (R = c) and aryl aldehyde 2 (R = c) in
3
2
dioxane was added BF -Et O gradually at 20 °C and stirred for 2 h. The mixture was then
3
2
extracted with ethyl acetate and washed with water and brine. It was further purified by
column chromatography to yield pure solid compound.
5.2. General method for the preparation of compound 6
3
A mixture of aryl ketone 1 (R = d-h), iodine (1.2 eq.) and pyridine (15 eq.) was refluxed at
140 °C for 3 h. Precipitate occurred during reaction which was cooled to room temperature.
3
Then it was filtered and washed with cold pyridine to afford compound 6 (R = d-h) in
quantitative yield. Five different pyridinium iodide salts were prepared by this method.
5.3. General method for the preparation of compounds 7, 8, and 9

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1
2
1
2
1
2
A mixture of propenone intermediate 3 (R = a, R = a-c), 4 (R = b, R = a-c), or 5 (R = c, R
3
=
a-c), pyridinium iodide salt 6 (R = d-h) and anhydrous ammonium acetate in glacial acetic
acid were heated at 90-100 °C for 12-24 h. The reaction mixture was then extracted with
ethyl acetate, washed with water and brine. The organic layer was dried with magnesium
sulfate and filtered. The filtrate was evaporated at reduced pressure, which was then purified
by silica gel column chromatography with the gradient elution of ethyl acetate / n-hexane to
1
2
3
1
2
3
1
afford solid compounds 7 (R = a, R = a-c, R = d-h), 8 (R = b, R = a-c, R = d-h), and 9 (R
2
3
=
c, R = a-c, R = d-h) in 20–94% yield. Forty-five dihydroxylated 2,4-diphenyl-6-aryl
pyridines (15-59) were synthesized by this method.
5.3.1. 2,2'-[6-(Thiophen-3-yl)pyridine-2,4-diyl]diphenol (15)
1
2
The general procedure was employed with 3 (R , R = a) (480.50 mg, 2.00 mmol), dry
3
ammonium acetate (1.54 g, 20.00 mmol), 6 (R = d) (662.34 mg, 2.00 mmol) and acetic acid
(
2 mL) to yield a yellow solid (140.60 mg, 20.4%, 0.40 mmol). mp 211-212 °C; R (ethyl
f
+
acetate/n-hexane 1:2 v/v): 0.37. LC/MS/MS: retention time: 8.93 min, [MH] : 346.23
1
purity by HPLC: 98%. H NMR (250 MHz, DMSO-d ) δ 14.48 (s, 1H, 2-phenyl 2-OH),
6
1
0.01 (br, 1H, 4-phenyl 2-OH), 8.26 (dd, J = 2.6, 1.1 Hz, 1H, 6-thiophene H-2), 8.22 (s, 1H,
pyridine H-3), 8.09 (d, J = 8.1 Hz, 1H, 2-phenyl H-6), 8.04 (s, 1H, pyridine H-5), 7.79-7.71
m, 2H, 6-thiophene H-4, H-5), 7.57 (dd, J = 7.6, 1.1 Hz, 1H, 4-phenyl H-6), 7.35-7.27 (m,
(
2H, 2-phenyl H-4, 4-phenyl H-4), 7.04-6.90 (m, 4H, 2-phenyl H-3, H-5, 4-phenyl H-3, H-5).
1
3
C NMR (62.5 MHz, DMSO-d ) δ 159.33, 156.45, 155.04, 149.78, 149.74, 140.47, 131.54,
6
1
1
30.68, 128.23, 127.42, 125.99, 125.11, 125.04, 119.84, 119.49, 119.27, 119.14, 118.48,
18.01, 116.55.
5.3.2. 2,2'-[6-(Furan-2-yl)pyridine-2,4-diyl]diphenol (16)

ACCEPTED MANUSCRIPT
1
2
The general procedure was employed with 3 (R , R = a) (480.50 mg, 2.00 mmol), dry
3
ammonium acetate (1.54 g, 20.00 mmol), 6 (R = e) (630.22 mg, 2.00 mmol) and acetic acid
(
2 mL) to yield a yellow solid (510.90 mg, 77.6%, 1.55 mmol). mp 215-216 °C; R (ethyl
f
+
acetate/n-hexane 1:2 v/v): 0.43, LC/MS/MS: retention time: 8.66 min, [MH] : 330.23
1
purity by HPLC: 100%, H NMR (250 MHz, DMSO-d ) δ 14.27 (s, 1H, 2-phenyl 2-OH),
6
1
0.05 (br, 1H, 2-phenyl 2-OH), 8.20 (d, J = 0.9 Hz, 1H, pyridine H-3), 8.10 (dd, J = 7.9, 1.1
Hz, 1H, 2-phenyl H-6), 7.99 (d, J = 1.0 Hz, 1H, pyridine H-5), 7.95 (d, J = 1.1 Hz, 1H, 6-
furan H-5), 7.57 (dd, J = 7.6, 1.5 Hz, 1H, 4-phenyl H-6), 7.36-7.27 (m, 2H, 2-phenyl H-4, 4-
phenyl H-4), 7.26 (d, J = 3.5 Hz, 1H, 6-furan H-3), 7.04-6.90 (m, 4H, 2-phenyl H-3, H-5, 4-
1
3
phenyl H-3, H-5), 6.74 (dd, J = 3.4, 1.7 Hz, 1H, 6-furan H-4). C NMR (62.5 MHz, DMSO-
d6) δ 159.40, 156.63, 155.11, 151.59, 149.58, 145.28, 145.11, 131.73, 130.87, 130.70, 127.51,
124.78, 119.94, 119.17, 119.09, 118.37, 118.19, 117.41, 116.61, 112.87, 110.16.
5.3.3. 2,2'-[(2,2'-Bipyridine)-4,6-diyl]diphenol (17)
1
2
The general procedure was employed with 3 (R , R = a) (480.50 mg, 2.00 mmol), dry
3
ammonium acetate (1.54 g, 20.00 mmol), 6 (R = f) (652.26 mg, 2.00 mmol) and acetic acid
(2 mL) to yield a greenish yellow solid (332.30 mg, 48.9%, 0.97 mmol). mp 201-202 °C; Rf
+
(
ethyl acetate/n-hexane 1:2 v/v): 0.34. LC/MS/MS: retention time: 8.43 min, [MH] : 341.27.
1
purity by HPLC: 98%, H NMR (250 MHz, DMSO-d ) δ 14.04 (s, 1H, 6-phenyl 2-OH),
6
1
0.06 (br, 1H, 4-phenyl 2-OH), 8.78 (d, J = 4.1 Hz, 1H, 2-pyridine H-6'), 8.55 (s, 1H,
pyridine H-3), 8.37 (s, 1H, pyridine H-5), 8.22 (d, J = 7.9 Hz, 1H, 2-pyridine H-3'), 8.15 (d, J
7.8 Hz, 1H, 6-phenyl H-6), 8.06 (t, J = 7.7 Hz, 1H, 2-pyridine H-4'), 7.59 (d, J = 7.4 Hz,
H, 4-phenyl H-6), 7.54 (d, J = 7.4 Hz, 1H, 2-pyridine H-5'), 7.37-7.29 (m, 2H, 6-phenyl H-4,
=
1
4
1
3
-phenyl H-4), 7.05-6.93 (m, 4H, 6-phenyl H-3, H-5, 4-phenyl H-3, H-5). C NMR (62.5
MHz, DMSO-d ) δ 159.00, 156.65, 155.14, 154.28, 152.62, 150.10, 149.58, 138.09, 131.62,
6

ACCEPTED MANUSCRIPT
1
1
30.85, 130.70, 127.93, 124.96, 124.87, 120.67, 120.56, 120.03, 119.86, 119.32, 117.99,
16.66.
5.3.4. 2,2'-[(2,3'-Bipyridine)-4,6-diyl]diphenol (18)
1
2
The general procedure was employed with 3 (R , R = a) (480.50 mg, 2.00 mmol), dry
3
ammonium acetate (1.54 g, 20.00 mmol), 6 (R = g) (652.26 mg, 2.00 mmol) and acetic acid
(2 mL) to yield a greenish yellow solid (481.10 mg, 70.7%, 1.41 mmol). mp 268-269 °C; Rf
+
(
ethyl acetate/n-hexane 1:2 v/v): 0.26. LC/MS/MS: retention time: 7.69 min, [MH] : 341.26,
1
purity by HPLC: 95%, H NMR (250 MHz, DMSO-d ) δ 13.87 (br, 1H, 6-phenyl 2-OH),
6
1
1
0.15 (br, 1H, 4-phenyl 2-OH), 9.23 (d, J = 1.8 Hz, 1H, 2-pyridine H-2'), 8.72 (dd, J = 4.7,
.3 Hz, 1H, 2-pyridine H-6'), 8.42 (dt, J = 8.3, 1.8 Hz, 1H, 2-pyridine H-4'), 8.37 (s, 1H,
pyridine H-3), 8.15 (s, 1H, pyridine H-5), 8.11 (d, J = 7.3 Hz, 1H, 6-phenyl H-6), 7.63-7.59
m, 1H, 2-pyridine H-5'), 7.62 (d, J = 7.4 Hz, 1H, 4-phenyl H-6), 7.37-7.28 (m, 2H, 6-phenyl
(
1
3
H-4, 4-phenyl H-4), 7.05-6.92 (m, 4H, 6-phenyl H-3, H-5, 4-phenyl H-3, H-5). C NMR
62.5 MHz, DMSO-d ) δ 158.97, 157.01, 155.24, 151.69, 150.64, 149.77, 148.01, 134.46,
(
6
1
1
33.80, 131.69, 130.87, 127.90, 124.85, 124.40, 120.20, 119.91, 119.83, 119.40, 117.99,
16.64.
5.3.5. 2,2'-[(2,4'-Bipyridine)-4,6-diyl]diphenol (19)
1
2
The general procedure was employed with 3 (R , R = a) (480.50 mg, 2.00 mmol), dry
3
ammonium acetate (1.54 g, 20.00 mmol), 6 (R = h) (652.26 mg, 2.00 mmol) and acetic acid
(2 mL) to yield a greenish yellow solid (233.50 mg, 34.3%, 0.68 mmol). mp 234-235 °C; Rf
+
(
ethyl acetate/n-hexane 2:1 v/v): 0.24. LC/MS/MS: retention time: 7.68 min, [MH] : 341.28.
1
purity by HPLC: 95%. H NMR (250 MHz, DMSO-d ) δ 13.66 (s, 1H, 6-phenyl 2-OH),
6
1
0.07 (s, 1H, 4-phenyl 2-OH), 8.79 (d, J = 4.6 Hz, 2H, 2-pyridine H-2', H-6'), 8.40 (s, 1H,

ACCEPTED MANUSCRIPT
pyridine H-3), 8.21 (s, 1H, pyridine H-5), 8.12 (d, J = 7.3 Hz, 1H, 6-phenyl H-6), 8.02 (dd, J
=
4.6, 1.5 Hz, 2H, 2-pyridine H-3', H-5'), 7.62 (dd, J = 7.6, 1.5 Hz, 1H, 4-phenyl H-6), 7.37-
7
3
1
1
.29 (m, 2H, 6-phenyl H-4, 4-phenyl H-4), 7.05-6.93 (m, 4H, 6-phenyl H-3, H-5, 4-phenyl H-
1
3
, H-5). C NMR (62.5 MHz, DMSO-d ) δ 158.82, 157.07, 155.15, 151.51, 150.92, 149.80,
6
45.13, 131.73, 130.93, 130.86, 128.07, 124.74, 121.10, 121.03, 120.47, 119.96, 119.94,
19.44, 117.94, 116.62.
5.3.6. 2-[4-(3-Hydroxyphenyl)-6-(thiophen-3-yl)pyridin-2-yl]phenol (20)
1
2
The general procedure was employed with 3 (R = a, R = b) (360.37 mg, 1.50 mmol), dry
3
ammonium acetate (1.15 g, 15.00 mmol), 6 (R = d) (496.75 mg, 1.5 mmol) and acetic acid
(
2 mL) to yield a yellow solid (471.00 mg, 90.90%, 1.36 mmol). mp 209-210 °C; R (ethyl
f
+
acetate/n-hexane 1:2 v/v): 0.37. LC/MS/MS: retention time: 8.80 min, [MH] : 346.23. purity
1
by HPLC: 100%. H NMR (250 MHz, DMSO-d ) δ 14.40 (br, 1H, 2-phenyl 2-OH), 9.80 (br,
6
1
H, 4-phenyl 3-OH), 8.36 (dd, J = 2.7, 1.4 Hz, 1H, 6-thiophene H-2), 8.27 (s, 1H, pyridine
H-3), 8.23 (d, J = 8.1 Hz, 1H, 2-phenyl H-6), 8.12 (d, J = 0.8 Hz, 1H, pyridine H-5), 7.81 (dd,
J = 5.0, 1.3 Hz, 1H, 6-thiophene H-4), 7.77 (dd, J = 5.0, 2.8 Hz, 1H, 6-thiophene H-5), 7.45 (t,
J = 7.8 Hz, 1H, 2-phenyl H-4), 7.39-7.30 (m, 3H, 4-phenyl H-5, H-6, H-2), 6.97-6.92 (m, 3H,
1
3
4
1
1
-phenyl H-4, 2-phenyl H-3, H-5). C NMR (62.5 MHz, DMSO-d ) δ 150.36, 149.24,
6
48.28, 141.98, 141.60, 131.37, 129.83, 122.71, 121.34, 119.20, 118.87, 117.15, 116.52,
10.26, 110.13, 109.40, 108.99, 107.87, 107.80, 106.91, 105.52.
5.3.7. 2-[6-(Furan-2-yl)-4-(3-hydroxyphenyl)pyridin-2-yl]phenol (21)
1
2
The general procedure was employed with 3 (R = a, R = b) (360.37 mg, 1.50 mmol), dry
3
ammonium acetate (1.15 g, 15.00 mmol), 6 (R = e) (472.66 mg, 1.50 mmol) and acetic acid
(
2 mL) to yield a yellow solid (395.70 mg, 80.1%, 1.20 mmol). mp 229-230 °C; R (ethyl
f

ACCEPTED MANUSCRIPT
+
acetate/n-hexane 1:1 v/v): 0.63. LC/MS/MS: retention time: 8.50 min, [MH] : 330.23. purity
1
by HPLC: 100%. H NMR (250 MHz, DMSO-d ) δ 14.24 (br, 1H, 2-phenyl 2-OH), 9.74 (br,
6
1
H, 4-phenyl 3-OH), 8.25 (d, J = 1.3 Hz, 1H, pyridine H-3), 8.23 (d, J = 7.9 Hz, 1H, 2-
phenyl H-6), 8.00 (s, 1H, pyridine H-5), 7.96 (d, J = 1.2 Hz, 1H, 6-furan H-5), 7.43-7.30 (m,
5
5
H, 2-phenyl H-4, 4-phenyl H-5, H-6, H-2, 6-furan H-3), 6.97-6.91 (m, 3H, 2-phenyl H-3, H-
1
3
, 4-phenyl H-4), 6.75 (dd, J = 3.4, 1.7 Hz, 1H, 6-furan H-4). C NMR (62.5 MHz, DMSO-
d6) δ 159.44, 158.24, 157.33, 151.41, 150.77, 145.92, 145.36, 138.60, 131.83, 130.43, 127.82,
119.09, 119.01, 118.31, 118.14, 116.91, 115.78, 114.67, 114.34, 112.87, 110.67.
5.3.8. 2-[4-(3-Hydroxyphenyl)-(2,2'-bipyridin)-6-yl]phenol (22)
1
2
The general procedure was employed with 3 (R = a, R = b) (360.37 mg, 1.50 mmol), dry
3
ammonium acetate (1.15 g, 15.00 mmol), 6 (R = f) (489.19 mg, 1.50 mmol) and acetic acid
(
2 mL) to yield a yellow solid (448.20 mg, 87.8%, 1.31 mmol). mp 277-278 °C; R (ethyl
f
+
acetate/n-hexane 1:2 v/v): 0.29. LC/MS/MS: retention time: 8.29 min, [MH] : 341.27. purity
1
by HPLC: 100%. H NMR (250 MHz, DMSO-d ) δ 13.93 (s, 1H, 6-phenyl 2-OH), 9.75 (s,
6
1
8
6
2
4
1
1
H, 4-phenyl 3-OH), 8.79 (d, J = 4.4 Hz, 1H, 2-pyridine H-6'), 8.50 (s, 1H, pyridine H-3),
.43 (s, 1H, pyridine H-5), 8.28 (d, J = 6.8 Hz, 1H, 2-pyridine H-3'), 8.23 (d, J = 7.1 Hz, 1H,
-phenyl H-6), 8.05 (td, J = 7.8, 1.6 Hz, 1H, 2-pyridine H-4'), 7.57 (dd, J = 6.5, 4.8 Hz, 1H,
-pyridine H-5'), 7.43-7.32 (m, 4H, 6-phenyl H-4, 4-phenyl H-5, H-6, H-2), 6.99-6.93 (m, 3H,
1
3
-phenyl H-4, 6-phenyl H-3, H-5). C NMR (62.5 MHz, DMSO-d ) δ 158.98, 158.30,
6
57.37, 154.02, 153.55, 150.66, 150.07, 138.77, 138.05, 131.72, 130.58, 128.26, 124.97,
20.79, 119.84, 119.25, 118.23, 118.15, 117.93, 117.00, 116.92, 114.15.
5.3.9. 2-[4-(3-Hydroxyphenyl)-(2,3'-bipyridin)-6-yl]phenol (23)

ACCEPTED MANUSCRIPT
1
2
The general procedure was employed with 3 (R = a, R = b) (360.37 mg, 1.50 mmol), dry
3
ammonium acetate (1.15 g, 15.00 mmol), 6 (R = g) (489.19 mg, 1.50 mmol) and acetic acid
(2 mL) to yield a light yellow solid (442.80 mg, 86.8%, 1.30 mmol). mp 249-250 °C; Rf
+
(
ethyl acetate/n-hexane 1:1 v/v): 0.29. LC/MS/MS: retention time: 7.52 min, [MH] : 341.26.
1
purity by HPLC: 100%. H NMR (250 MHz, DMSO-d ) δ 13.79 (s, 1H, 6-phenyl 2-OH),
6
9
1
8
2
5
5
1
1
.73 (s, 1H, 4-phenyl 3-OH), 9.30 (d, J = 1.8 Hz, 1H, 2-pyridine H-2'), 8.72 (d, J = 4.2 Hz,
H, 2-pyridine H-6'), 8.49 (d, J = 8.0 Hz, 1H, 2-pyridine H-4'), 8.38 (s, 1H, pyridine H-3),
.28 (d, J = 7.7 Hz, 6-phenyl H-6), 8.22 (s, 1H, pyridine H-5), 7.62 (dd, J = 7.9, 4.8 Hz, 1H,
-pyridine H-5'), 7.46 (t, J = 7.6 Hz, 1H, 6-phenyl H-4), 7.40 (t, J = 7.2 Hz, 1H, 4-phenyl H-
), 7.37-7.32 (m, 2H, 4-phenyl H-2, H-6), 6.98-6.93 (m, 3H, 4-phenyl H-4, 2-phenyl H-3, H-
1
3
). C NMR (62.5 MHz, DMSO-d ) δ 158.94, 158.23, 157.74, 152.53, 150.98, 150.68,
6
48.16, 138.73, 134.55, 133.59, 131.77, 130.39, 128.27, 124.28, 119.80, 119.32, 118.54,
17.91, 117.65, 117.37, 116.88, 114.58.
5.3.10. 2-[4-(3-Hydroxyphenyl)-(2,4'-bipyridin)-6-yl]phenol (24)
1
2
The general procedure was employed with 3 (R = a, R = b) (360.37 mg, 1.50 mmol), dry
3
ammonium acetate (1.15 g, 15.00 mmol), 6 (R = h) (489.19 mg, 1.50 mmol) and acetic acid
(
2 mL) to yield a yellow solid (366.00 mg, 71.7%, 1.07 mmol). mp 269-270 °C; R (ethyl
f
+
acetate/n-hexane 1:1 v/v): 0.23. LC/MS/MS: retention time: 7.53 min, [MH] : 341.28. purity
1
by HPLC: 99%. H NMR (250 MHz, DMSO-d ) δ 13.59 (br, 1H, 6-phenyl 2-OH), 9.75 (br,
6
1
H, 4-phenyl 3-OH), 8.80 (dd, J = 4.4, 1.5 Hz, 2H, 2-pyridine H-2', H-6'), 8.43 (s, 1H,
pyridine H-3), 8.27 (s, 1H, pyridine H-5), 8.25 (d, J = 5.4 Hz, 1H, 6-phenyl H-6), 8.10 (dd, J
4.7, 1.6 Hz, 2H, 2-pyridine H-3', H-5'), 7.48 (t, J = 7.7 Hz, 1H, 6-phenyl H-4), 7.40 (t, J =
.3 Hz, 1H, 4-phenyl H-5), 7.39-7.32 (m, 2H, 4-phenyl H-6, H-2), 6.99-6.94 (m, 3H, 4-
=
7
1
3
phenyl H-4, 6-phenyl H-3, H-5). C NMR (62.5 MHz, DMSO-d ) δ 158.80, 158.26, 157.77,
6

ACCEPTED MANUSCRIPT
1
1
52.38, 151.04, 150.84, 144.93, 138.61, 131.82, 130.42, 128.43, 121.20, 119.94, 119.37,
18.53, 117.92, 117.87, 116.93, 114.58.
5.3.11. 2-[4-(4-Hydroxyphenyl)-6-(thiophen-3-yl)pyridin-2-yl]phenol (25)
1
2
The general procedure was employed with 3 (R = a, R = c) (360.37 mg, 1.50 mmol), dry
3
ammonium acetate (1.15 g, 15.00 mmol), 6 (R = d) (496.75 mg, 1.50 mmol) and acetic acid
(
2 mL) to yield a yellow solid (208.20 mg, 40.2%, 0.60 mmol). mp 233-234 °C; R (ethyl
f
+
acetate/n-hexane 1:1 v/v): 0.58. LC/MS/MS: retention time: 8.65 min, [MH] : 346.23
1
purity by HPLC: 99%. H NMR (250 MHz, DMSO-d ) δ 14.64 (br, 1H, 2-phenyl 2-OH),
6
9
.95 (br, 1H, 4-phenyl 4-OH), 8.33 (dd, J = 2.4, 1.4 Hz, 1H, 6-thiophene H-2), 8.28 (s, 1H,
pyridine H-3), 8.25 (d, J = 8.0 Hz, 1H, 2-phenyl H-6), 8.12 (s, 1H, pyridine H-5), 7.97 (d, J =
.6 Hz, 2H, 4-phenyl H-2, H-6), 7.81 (dd, J = 5.4, 1.3 Hz, 1H, 6-thiophene H-4), 7.77 (dd, J
4.9, 2.9 Hz, 1H, 6-thiophene H-5), 7.33 (t, J = 8.2 Hz, 1H, 2-phenyl H-4), 6.95-6.92 (m, 2H,
8
=
1
3
2
-phenyl H-3, H-5), 6.96 (d, J = 8.49 Hz, 2H, 4-phenyl H-3, H-5). C NMR (62.5 MHz,
DMSO-d ) δ 159.52, 159.44, 157.25, 150.51, 150.41, 140.49, 131.65, 129.15, 128.17, 127.77,
6
127.62, 126.17, 125.33, 119.20, 119.05, 118.01, 116.08, 115.88, 114.66.
5.3.12. 2-[6-(Furan-2-yl)-4-(4-hydroxyphenyl)pyridin-2-yl]phenol (26)
1
2
The general procedure was employed with 3 (R = a, R = c) (288.30 mg, 1.20 mmol), dry
3
ammonium acetate (924.96 mg, 12.00 mmol), 6 (R = e) (378.13 mg, 1.20 mmol) and acetic
acid (2 mL) to yield a yellow solid (278.60 mg, 70.5%, 0.84 mmol). mp 241-242 °C; Rf
+
(
ethyl acetate/n-hexane 1:1 v/v): 0.48. LC/MS/MS: retention time: 8.39 min, [MH] : 330.23.
1
purity by HPLC: 98%. H NMR (250 MHz, DMSO-d ) δ 14.46 (br, 1H, 2-phenyl 2-OH),
6
9
.99 (br, 1H, 4-phenyl 4-OH), 8.28 (d, J = 8.1 Hz, 1H, 2-phenyl H-6), 8.26 (s, 1H, pyridine
H-3), 8.02 (s, 1H, pyridine H-5), 7.96 (d, J = 0.8 Hz, 1H, 6-furan H-5), 7.94 (d, J = 8.6 Hz,

ACCEPTED MANUSCRIPT
2H, 4-phenyl H-2, H-6), 7.37 (d, J = 3.1 Hz, 1H, 6-furan H-3), 7.33 (t, J = 8.3 Hz, 1H, 2-
phenyl H-4), 6.96-6.92 (m, 2H, 2-phenyl H-3, H-5), 6.95 (d, J = 8.5 Hz, 2H, 4-phenyl H-3,
1
3
H-5), 6.75 (dd, J = 3.3, 1.7 Hz, 1H, 6-furan H-4). C NMR (62.5 MHz, DMSO-d ) δ 159.60,
6
1
1
59.54, 157.28, 151.54, 150.34, 145.77, 145.28, 131.78, 129.09, 127.75, 127.42, 118.99,
18.18, 116.15, 114.57, 113.71, 112.86, 110.50.
5.3.13. 2-[4-(4-Hydroxyphenyl)-(2,2'-bipyridin)-6-yl]phenol (27)
1
2
The general procedure was employed with 3 (R = a, R = c) (240.25 mg, 1.00 mmol), dry
3
ammonium acetate (770.80 mg, 10.00 mmol), 6 (R = f) (326.13 mg, 1.00 mmol) and acetic
acid (2 mL) to yield a light yellow solid (117.50 mg, 34.5%, 0.34 mmol). mp 259-260 °C; Rf
+
(
ethyl acetate/n-hexane 2:1 v/v): 0.13. LC/MS/MS: retention time: 8.14 min, [MH] : 341.27.
1
purity by HPLC: 100%. H NMR (250 MHz, DMSO-d ) δ 14.27 (br, 1H, 6-phenyl 2-OH),
6
1
0.01 (br, 1H, 4-phenyl 4-OH), 8.79 (d, J = 4.0 Hz, 1H, 2-pyridine H-6'), 8.50 (s, 1H,
pyridine H-3), 8.42 (s, 1H, pyridine H-5), 8.30 (d, J = 8.1 Hz, 1H, 2-pyridine H-3'), 8.23 (d, J
7.9 Hz, 1H, 6-phenyl H-6), 8.06 (td, J = 7.8, 1.7 Hz, 1H, 2-pyridine H-4'), 7.92 (d, J = 8.6
Hz, 2H, 4-phenyl H-2, H-6), 7.54 (dd, J = 7.3, 4.8 Hz, 1H, 2-pyridine H-5'), 7.34 (td, J = 7.2,
.3 Hz, 1H, 6-phenyl H-4), 6.98-6.93 (m, 2H, 6-phenyl H-3, H-5), 6.97 (d, J = 8.6 Hz, 2H, 4-
=
1
1
3
phenyl H-3, H-5). C NMR (62.5 MHz, DMSO-d ) δ 159.51, 159.25, 157.36, 154.14, 153.32,
6
1
1
50.45, 150.10, 138.07, 131.71, 129.04, 128.10, 127.69, 124.95, 120.80, 119.62, 119.17,
18.01, 116.85, 116.28, 116.20.
5.3.14. 2-[4-(4-Hydroxyphenyl)-(2,3'-bipyridin)-6-yl]phenol (28)
1
2
The general procedure was employed with 3 (R = a, R = c) (360.37 mg, 1.50 mmol), dry
3
ammonium acetate (1.15 g, 15.00 mmol), 6 (R = g) (489.19 mg, 1.50 mmol) and acetic acid
(2 mL) to yield a light yellow solid (190.00 mg, 37.2%, 0.55 mmol). mp 324-325 °C; Rf

ACCEPTED MANUSCRIPT
+
(
ethyl acetate: n-hexane 1:1 v/v): 0.10. LC/MS/MS: retention time: 7.41 min, [MH] : 341.26.
1
purity by HPLC: 95%. H NMR (250 MHz, DMSO-d ) δ 14.11 (br, 1H, 6-phenyl 2-OH),
6
9
.99 (br, 1H, 4-phenyl 4-OH), 9.29 (d, J = 1.7 Hz, 1H, 2-pyridine H-2'), 8.70 (dd, J = 4.7, 1.2
Hz, 1H, 2-pyridine H-6'), 8.46 (d, J = 8.1 Hz, 1H, 2-pyridine H-4'), 8.38 (s, 1H, pyridine H-3),
.29 (d, J = 7.8 Hz, 1H, 6-phenyl H-6), 8.22 (s, 1H, pyridine H-5), 8.00 (d, J = 8.6 Hz, 2H, 4-
8
phenyl H-2, H-6), 7.62 (dd, J = 7.9, 4.7 Hz, 1H, 2-pyridine H-5'), 7.34 (t, J = 7.0 Hz, 1H, 6-
phenyl H-4), 6.99-6.92 (m, 2H, 6-phenyl H-3, H-5), 6.96 (d, J = 8.6 Hz, 2H, 4-phenyl H-3,
1
3
H-5). C NMR (62.5 MHz, DMSO-d ) δ 159.57, 159.22, 157.78, 152.31, 150.69, 150.65,
6
1
1
48.17, 134.54, 133.70, 131.79, 129.33, 128.12, 127.55, 124.34, 119.60, 119.27, 118.00,
16.73, 116.16, 115.99.
5.3.15. 2-[4-(4-Hydroxyphenyl)-(2,4'-bipyridin)-6-yl]phenol (29)
1
2
The general procedure was employed with 3 (R = a, R = c) (360.37 mg, 1.50 mmol), dry
3
ammonium acetate (1.15 g, 15.00 mmol), 6 (R = h) (489.19 mg, 1.50 mmol) and acetic acid
(2 mL) to yield a light yellow solid (233.40 mg, 45.7%, 0.68 mmol). mp 358-359 °C; Rf
+
(
ethyl acetate/n-hexane 1:1 v/v): 0.10. LC/MS/MS: retention time: 7.40 min, [MH] : 341.29.
1
purity by HPLC: 95%. H NMR (250 MHz, DMSO-d ) δ 13.84 (br, 1H, 6-phenyl 2-OH),
6
9
1
2
.82 (br, 1H, 4-phenyl 4-OH), 8.80 (dd, J = 4.6, 1.4 Hz, 2H, 2-pyridine H-2', H-6'), 8.42 (s,
H, pyridine H-3), 8.28-8.26 (m, 2H, 6-phenyl H-6, pyridine H-5), 8.07 (dd, J = 4.6, 1.5 Hz,
H, 2-pyridine H-3', H-5'), 7.99 (d, J = 8.6 Hz, 2H, 4-phenyl H-2, H-6), 9.37 (td, J = 7.8, 0.9
Hz, 1H, 6-phenyl H-4), 7.00-6.93 (m, 2H, 6-phenyl H-3, H-5), 6.97 (d, J = 8.5 Hz, 2H, 4-
1
3
phenyl H-3, H-5). C NMR (62.5 MHz, DMSO-d ) δ 159.52, 158.95, 157.71, 152.09, 150.73,
6
1
1
44.94, 131.66, 129.16, 128.11, 127.34, 121.06, 119.64, 119.17, 117.83, 116.98, 116.87,
16.07, 115.54.

ACCEPTED MANUSCRIPT
5.3.16. 2-[2-(3-Hydroxyphenyl)-6-(thiophen-3-yl)pyridin-4-yl]phenol (30)
1
2
The general procedure was employed with 4 (R = b, R = a) (360.37 mg, 1.50 mmol), dry
3
ammonium acetate (1.15 g, 15.00 mmol), 6 (R = d) (496.75 mg, 1.50 mmol) and acetic acid
(
2 mL) to yield a white solid (299.30 mg, 57.8%, 0.86 mmol). mp 162-163 °C; R (ethyl
f
+
acetate/n-hexane 1: 1 v/v): 0.56. LC/MS/MS: retention time: 7.81 min, [MH] : 346.22. purity
1
by HPLC: 100%. H NMR (250 MHz, DMSO-d ) δ 9.88 (br, 1H, 4-phenyl 2-OH), 9.60 (br,
6
1
H, 2-phenyl 3-OH), 8.28 (dd, J = 2.9, 1.0 Hz, 1H, 6-thiophene H-2), 7.94 ( s, 1H, pyridine
H-3), 7.90 (d, J = 1.2 Hz, 1H, pyridine H-5), 7.89 (dd, J = 4.9, 1.0 Hz, 1H, 6-thiophene H-4),
.69 (dd, J = 5.0, 3.0 Hz, 1H, 6-thiophene H-5), 7.62 (t, J = 1.9 Hz, 1H, 2-phenyl H-2), 7.59
d, J = 7.9 Hz, 1H, 2-phenyl H-6), 7.52 (dd, J = 7.6, 1.5 Hz, 1H, 4-phenyl H-6), 7.30 (t, J =
7
(
7
1
2
1
1
.9 Hz, 1H, 2-phenyl H-5), 7.26 (td, J = 7.6, 1.5 Hz, 1H, 4-phenyl H-4), 7.02 (d, J = 8.1 Hz,
H, 4-phenyl H-3), 6.95 (td, J = 7.8, 1.1 Hz, 1H, 4-phenyl H-5), 6.85 (dd, J = 7.8, 2.0 Hz, 1H,
1
3
-phenyl H-4). C NMR (62.5 MHz, DMSO-d ) δ 157.97, 155.66, 155.01, 152.56, 148.34,
6
42.54, 140.56, 130.60, 130.29, 129.97, 127.16, 126.82, 125.50, 124.33, 119.85, 119.26,
18.96, 117.66, 116.52, 116.26, 113.72.
5.3.17. 2-[2-(Furan-2-yl)-6-(3-hydroxyphenyl)pyridin-4-yl]phenol (31)
1
2
The general procedure was employed with 4 (R = b, R = a) (360.37 mg, 1.50 mmol), dry
3
ammonium acetate (1.15 g, 15.00 mmol), 6 (R = e) (472.66 mg, 1.50 mmol) and acetic acid
(
2 mL) to yield an off-white solid (296.30 mg, 60.0%, 0.89 mmol). mp 199-200 °C; R (ethyl
f
+
acetate/n-hexane 1:1 v/v): 0.55. LC/MS/MS: retention time: 7.50 min, [MH] : 330.21. purity
1
by HPLC: 100%. H NMR (250 MHz, DMSO-d ) δ 9.93 (s, 1H, 4-phenyl 2-OH), 9.58 (s, 1H,
6
6
-phenyl 3-OH), 7.88 (s, 2H, pyridine H-3, H-5), 7.86 (d, J = 0.8 Hz, 1H, 2-furan H-5), 7.60
d, J = 1.6 Hz, 1H, 6-phenyl H-2), 7.58 (d, J = 8.3 Hz, 1H, 6-phenyl H-6), 7.53 (dd, J = 7.6,
.4 Hz, 1H, 4-phenyl H-6), 7.30 (t, J = 7.9 Hz, 1H, 6-phenyl H-5), 7.27 (td, J = 7.7, 1.6 Hz,
(
1

ACCEPTED MANUSCRIPT
1H, 4-phenyl H-4), 7.22 (d, J = 3.3 Hz, 1H, 2-furan H-3), 7.03 (d, J = 8.1 Hz, 1H, 4-phenyl
H-3), 6.95 (t, J = 7.7 Hz, 1H, 4-phenyl H-5), 6.86 (dd, J = 7.8, 2.0 Hz, 1H, 6-phenyl H-4),
1
3
6
1
1
.69 (dd, J = 3.3, 1.7 Hz, 1H, 2-furan H-4). C NMR (62.5 MHz, DMSO-d ) δ 157.95,
6
56.17, 155.00, 153.65, 148.39, 148.16, 144.33, 140.24, 130.45, 129.96, 125.10, 119.96,
19.00, 117.72, 117.26, 116.59, 116.40, 113.74, 112.52, 109.14.
5.3.18. 2-[6-(3-Hydroxyphenyl)-(2,2'-bipyridin)-4-yl]phenol (32)
1
2
The general procedure was employed with 4 (R = b, R = a) (360.37 mg, 1.50 mmol), dry
3
ammonium acetate (1.15 g, 15.00 mmol), 6 (R = f) (489.19 mg, 1.50 mmol) and acetic acid
(
2 mL) to yield a yellow solid (377.60 mg, 74.0%, 1.10 mmol). mp 198-199 °C; R (ethyl
f
+
acetate/n-hexane 1:1 v/v): 0.47. LC/MS/MS: retention time: 7.28 min, [MH] : 341.28. purity
1
by HPLC: 99%. H NMR (250 MHz, DMSO-d ) δ 9.86 (br, 1H, 4-phenyl 2-OH), 9.61 (br,
6
1
H, 6-phenyl 3-OH), 8.71 (d, J = 3.9 Hz, 1H, 2-pyridine H-6'), 8.59-8.57 (m, 2H, 2-pyridine
H-3', pyridine H-3), 8.06 (s, 1H, pyridine H-5), 8.00 (t, J = 7.7 Hz, 1H, 2-pyridine H-4'), 7.69
s, 1H, 6-phenyl H-2), 7.65 (d, J = 7.7 Hz, 1H, 6-phenyl H-6), 7.54 (t, J = 8.3 Hz, 1H, 2-
pyridine H-5'), 7.48 (d, J = 7.1 Hz, 1H, 4-phenyl H-6), 7.35 (t, J = 7.9 Hz, 1H, 6-phenyl H-5),
.29 (t, J = 8.0 Hz, 1H, 4-phenyl H-4), 7.04 (d, J = 8.1 Hz, 1H, 4-phenyl H-3), 6.97 (t, J = 7.5
(
7
1
3
Hz, 1H, 4-phenyl H-5), 6.88 (d, J = 7.7 Hz, 1H, 6-phenyl H-4). C NMR (62.5 MHz,
DMSO-d ) δ 157.97, 155.77, 155.72, 154.96, 154.88, 149.43, 148.34, 140.33, 137.45, 130.35,
6
129.95, 125.33, 124.33, 120.81, 120.59, 119.91, 119.49, 117.67, 116.58, 116.34, 113.71.
5.3.19. 2-[6-(3-Hydroxyphenyl)-(2,3'-bipyridin)-4-yl]phenol (33)
1
2
The general procedure was employed with 4 (R = b, R = a) (360.37 mg, 1.50 mmol), dry
3
ammonium acetate (1.15 g, 15.00 mmol), 6 (R = g) (489.19 mg, 1.50 mmol) and acetic acid
(
2 mL) to yield an off-white solid (265.60 mg, 52.0%, 0.78 mmol). mp 250-251 °C; R (ethyl
f

ACCEPTED MANUSCRIPT
+
acetate/n-hexane 1:1 v/v): 0.23. LC/MS/MS: retention time: 6.66 min, [MH] : 341.25. purity
1
by HPLC: 99%. H NMR (250 MHz, DMSO-d ) δ 9.94 (br, 1H, 4-phenyl 2-OH), 9.59 (br,
6
1
2
H, 6-phenyl 3-OH), 9.40 (d, J = 1.7 Hz, 1H, 2-pyridine H-2'), 8.66 (dd, J = 4.7, 1.4 Hz, 1H,
-pyridine H-6'), 8.57 (dt, J = 8.0, 1.7 Hz, 1H, 2-pyridine H-4'), 8.12 (d, J = 0.9 Hz, 1H,
pyridine H-3), 8.06 (d, J = 0.8 Hz, 1H, pyridine H-5), 7.68 (t, J = 1.8 Hz, 1H, 6-phenyl H-2),
7
.62 (d, J = 7.4 Hz, 1H, 6-phenyl H-6), 7.59 (d, J = 7.5 Hz, 1H, 4-phenyl H-6), 7.56 (dd, J =
.9, 5.0 Hz, 1H, 2-pyridine H-5'), 7.31 (t, J = 7.8 Hz, 1H, 6-phenyl H-5), 7.28 (td, J = 7.8, 1.5
7
Hz, 1H, 4-phenyl H-4), 7.04 (d, J = 8.1 Hz, 1H, 4-phenyl H-3), 6.96 (td, J = 7.9, 1.0 Hz, 1H,
1
3
4
-phenyl H-5), 6.87 (dd, J = 7.9, 2.1 Hz, 1H, 6-phenyl H-4). C NMR (62.5 MHz, DMSO-
d6) δ 158.02, 156.11, 155.03, 153.61, 150.06, 148.63, 148.23, 140.33, 134.64, 134.36, 130.69,
130.44, 130.04, 125.22, 124.00, 119.94, 119.90, 119.62, 117.70, 116.55, 116.44, 113.74.
5.3.20. 2-[6-(3-Hydroxyphenyl)-(2,4'-bipyridin)-4-yl]phenol (34)
1
2
The general procedure was employed with 4 (R = b, R = a) (360.37 mg, 1.50 mmol), dry
3
ammonium acetate (1.15 g, 15.00 mmol), 6 (R = h) (489.19 mg, 1.50 mmol) and acetic acid
(
2 mL) to yield an off-white solid (204.60 mg, 40.0%, 0.60 mmol). mp 263-264 °C; R (ethyl
f
+
acetate/n-hexane 1:1 v/v): 0.13. LC/MS/MS: retention time: 6.69 min, [MH] : 341.27. purity
1
by HPLC: 95%. H NMR (250 MHz, DMSO-d ) δ 9.97 (br, 1H, 4-phenyl 2-OH), 9.61 (br,
6
1
H, 6-phenyl 3-OH), 8.74 (d, J = 4.5 Hz, 2H, 2-pyridine H-2', H-6'), 8.20-8.18 (m, 3H, 2-
pyridine H-3', H-5', pyridine H-3), 8.11 (s, 1H, pyridine H-5), 7.67 (s, 1H, 6-phenyl H-2),
7
4
7
1
1
.63-7.56 (m, 2H, 6-phenyl H-6, 4-phenyl H-6), 7.35-7.27 (m, 2H, 6-phenyl H-5, 4-phenyl H-
), 7.05 (d, J = 8.7 Hz, 1H, 4-phenyl H-3), 6.97 (t, J = 7.5 Hz, 1H, 4-phenyl H-5), 6.89 (d, J =
1
3
.3 Hz, 1H, 6-phenyl H-4). C NMR (62.5 MHz, DMSO-d ) δ 158.03, 156.24, 155.03,
6
53.25, 150.55, 148.77, 146.14, 140.19, 130.69, 130.53, 130.07, 125.07, 121.16, 120.94,
20.02, 119.92, 117.76, 116.55, 113.76.