Aryl and Arylalkyl Substituted 3-Hydroxypyridin-2(1H)-ones: Synthesis and Evaluation as Inhibitors of Influenza A Endonuclease

Article abstract of DOI:10.1002/cmdc.201900084

Seasonal influenza infections are associated with an estimated 250–500 000 deaths annually. Resistance to the antiviral M2 ion-channel inhibitors has largely invalidated their clinical utility. Resistance to neuraminidase inhibitors has also been observed in several influenza A virus (IAV) strains. These data have prompted research on inhibitors that target the cap-snatching endonuclease activity of the polymerase acidic protein (PA). Baloxavir marboxil (Xofluza), recently approved for clinical use, inhibits cap-snatching endonuclease. Resistance to Xofluza has been reported in both in vitro systems and in the clinic. An X-ray crystallographic screening campaign of a fragment library targeting IAV endonuclease identified 5-chloro-3-hydroxypyridin-2(1H)-one as a bimetal chelating agent at the active site. We have reported the structure–activity relationships for 3-hydroxypyridin-2(1H)-ones and 3-hydroxyquinolin-2(1H)-ones as endonuclease inhibitors. These studies identified two distinct binding modes associated with inhibition of this enzyme that are influenced by the presence of substituents at the 5- and 6-positions of 3-hydroxypyridin-2(1H)-ones. Herein we report the structure–activity relationships associated with various para-substituted 5-phenyl derivatives of 6-(p-fluorophenyl)-3-hydroxypyridin-2(1H)-ones and the effect of using naphthyl, benzyl, and naphthylmethyl groups as alternatives to the p-fluorophenyl substituent on their activity as endonuclease inhibitors.

Full text of DOI:10.1002/cmdc.201900084

Accepted Article
Title: Aryl and arylalkyl substituted 3-hydroxypyridin(1H)-2-
ones: Synthesis and evaluation as inhibitors of influenza A
endonuclease
Authors: Edmond J. LaVoie, Hye Yeon Sagong, Joseph D. Bauman,
Aitor Nogales, Luis Martínez-Sobrido, and Eddy Arnold
This manuscript has been accepted after peer review and appears as an
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ChemMedChem
10.1002/cmdc.201900084
1
Aryl and arylalkyl substituted 3-hydroxypyridin(1H)-2-ones: Synthesis and evaluation as
inhibitors of influenza A endonuclease
a
b
c
c
Hye Yeon Sagong , Joseph D. Bauman , Aitor Nogales , Luis Martínez-Sobrido ,
b*
a*
Eddy Arnold , and Edmond J. LaVoie
a
Department of Medicinal Chemistry, Ernest Mario School of Pharmacy,
Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854-8020, U.S.A.
b
Center for Advanced Biotechnology and Medicine and Department of Chemistry and Chemical
Biology, Rutgers University, Piscataway, New Jersey, 08854-5627, U.S.A.
c
Department of Microbiology and Immunology, University of Rochester, Rochester, New York
1
4642, USA
INTRODUCTION
An estimated 250-500,000 deaths annually are associated with seasonal influenza viral
[
1]
infection. While vaccines as a prophylactic have been available, because of the continual
antigenic drift variation of influenza viruses, their effectiveness is highly dependent upon the
correct prediction of the dominant infectious strain for any given year.[ Moreover, it is not
possible to generate prophylactic options against potential pandemic virus strains. There are
three classes of FDA-approved clinical agents that have been developed for the treatment and
prophylaxis of influenza infection. These consist of agents that targeted the matrix 2 (M2) ion-
channel, neuraminidase (NA), and recently the cap-snatching endonuclease activity of the
polymerase acidic protein (PA). Resistance to the M2 ion-channel inhibiting drugs, amantadine
2]
[
3,4]
and rimantadine, has largely invalidated their clinical utility.
Resistance to NA inhibitors,
®
including oseltamivir (Tamiflu ), has also been observed in several seasonal influenza A
[
5,6]
strains.
There has been intensive research on inhibitors of the cap-snatching endonuclease
activity of PA. Structural studies on influenza A endonuclease and on the binding modes of
[
7-10]
various inhibitors of influenza virus PA endonuclease have been recently reported.
addition, advances have been made in understanding the structure-activity relationships
In
[
11]
associated with metal-binding pharmacophores to influenza endonuclease.
Evidence has also
been provided that suggest that resistance to experimental endonuclease inhibitors, such as L-
7
42,001 can occur through specific mutations highlighting this potential and concern in the
[
12]
development of clinical endonuclease inhibitors.
Xofluza, baloxavir marboxil, is a prodrug
that has been recently approved to target the cap-snatching endonuclease. However, resistance
to Xofluza has been reported in both clinical and in vitro systems, but with significant decrease
[
13,14]
in viral fitness.
Influenza A virus (IAV) has eight negative-stranded RNA genomic segments. The three largest
genomic RNA segments encode the viral RNA-dependent RNA polymerase (RdRp) subunits,
which consist of the polymerase acidic protein (PA) and the two polymerase basic proteins 1
(PB1) and 2 (PB2). The PA subunit has endonuclease activity, is involved in viral RNA
This article is protected by copyright. All rights reserved.

ChemMedChem
10.1002/cmdc.201900084
2
(
vRNA)/complementary RNA (cRNA) promoter binding, and interacts with the PB1 subunit.[15]
PA has two domains, PA and PA . Crystal structures of PA have been elucidated in
complexes with N-terminal fragments of PB1.
N
C
C
[
16]
The structure of PA has been solved both
N
unliganded and with various ligands in several crystal forms.[
17-22]
Influenza RdRp is essential for the replication and transcription of the segmented viral RNA
genes. Viral mRNA transcription involves a cap-snatching mechanism wherein the polymerase
binds to the host cellular mRNA via the 5’-cap and cleaves the mRNA 12-13 nucleotides
downstream. This cleaved host mRNA fragment, which contains the 5’ cap, then acts as a
[
23]
primer for viral mRNA synthesis.
Cap-snatching is a critical event in the life cycle of all
members of the Orthomyxoviridae family of viruses, including influenza A, B, and C viruses.
As mammalian cells do not participate in an analogous activity, inhibitors of cap-snatching can
®
be selective against multiple influenza types, subtypes and strains, including Tamiflu -resistant
IAV, as well as against IBV and subtypes resistant to M2 inhibitors, without interfering with
function of the host cell (for example Xofluza) .[
24]
In addition to Xofluza and related compounds several different classes of influenza endonuclease
[
19,20,25,26]
inhibitors have been described. These include 2,4-dioxobutanoic acid derivatives ,
5-
[
20]
hydroxy-1,6-dihydropyrimidine-4-carboxylic acid derivatives,
flutimide and its derivatives
2-hydroxyphenyl amide derivatives, salicylaldehyde thiosemicabazones, various types
pyromeconic acid and pyridinone deriviatives, N-acylhydrazone derivatives
5-hydrox-4-pyridone-3-carboxy acid derivatives, 4,5-dihydroxypyrimidine-6-carboxamide
[
27]
[28]
[29]
,
[
30,31]
[32]
of catechins,
,
[
33]
[34]
[
35]
[36]
derivatives, as well as tetramic acid derivatives.
From an X-ray crystallographic screening campaign of a fragment library targeting the IAV
endonuclease enzyme, we identified the 5-chloro-3-hydroxypyridin-2(1H)-one as a bimetal
chelating ligand at the active site of the enzyme.[ Using this information, we have reported the
structure-activity relationships for two new series of compounds; 3-hydroxypyridin-2(1H)-ones
22]
[
37,38]
and 3-hydroxyquinolin-2(1H)-ones, as endonuclease inhibitors.
We also examined the
relative activity of various aza-analogs of 3-hydroxypyridin-2(1H)-one.[39]
Substituted 3-hydroxypyridin(1H)-2-ones can be effective inhibitors of IAV endonuclease
(Figure 1). Studies from our laboratories have demonstrated that there are two distinct binding
metal modes associated with inhibition of this enzyme that can be influenced by the presence of
substituents on the phenyl groups at the 5- and 6-positions of 3-hydroxypyridin(1H)-2-ones. The
data suggest the presence of a 5-tetrazoyl moiety at the para position of the 5-phenyl substituent
of 2 is associated with enhanced activity relative to the 4-(p-cyanophenyl) derivative, 1. It is also
more active than similar 5-phenyl-6-(p-fluorophenyl)-3-hydroxypyridin((1H)-2-ones wherein the
5
-phenyl moiety is substituted at the meta-position with a cyano, 5-tetrazolyl, or carboxyl group,
3
-5. A similar, but less notable effect was observed in examining the relative inhibitory activity
of 5-(p-fluorophenyl)-3-hydroxypyridin(1H)-2-ones with a 6-phenyl group where 7 is more
active than 6 as an inhibitor.
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ChemMedChem
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Figure 1. Previously reported 3-hydroxypyridin(1H)-2-ones as inhibitors of IAV endonuclease.
The present study examines the structure-activity relationships associated with various para-
substituted 5-phenyl derivatives of 6-(p-fluorophenyl)-3-hydroxypyridin (1H)-2-one. In
addition, this investigation includes an assessment of the effect of using naphthyl, benzyl, and
naphthylmethyl groups as alternatives to the p-fluorophenyl substituent at either the 5- or 6-
position of these 3-hydroxypyridin (1H)-2-ones in both of these two sets of compounds on their
activity as endonuclease inhibitors. The insertion of a methylene group between phenyl or
naphthyl substituents at either the 5 or 6 positions of these 3-hydroxypyridin (1H)-2-ones
significantly decreases rigidity, permitting greater molecular flexibility. Such modifications
could permit enhanced inhibitory activity by permitting such analogs to adopt a greater binding
affinity at the active site. The effect of these structural variations on inhibitory activity was
evaluated.
Chemistry
The synthetic approach used in the preparation of 8 and 10, as well as the tetrazoyl derivative 9
was identical to that previously used for the preparation of 1 to 4 (Scheme 1).2 Commercially-
available 2,3-dimethoxypyridine was treated with N-bromosuccinimide to provide 5-bromo-2,3-
dimethoxypyridine. Suzuki-coupling using p-cyanophenylboronic acid provided 5-(p-
cyanophenyl)-2,3-dimethoxypyridine, which was converted as previously described to 6-bromo-
5
5
-(p-cyanophenyl)-2,3-dimethoxypyridine, intermediate A. This intermediate was then used to
prepare 8 and 10. Compound 8 was then converted to the tetrazoyl derivative 9 using sodium
azide in DMF with a catalytic amount of acetic acid.[ Compound 10 was treated under similar
conditions. While the tetrazole derivative of 10 was formed under these conditions, it proved to
be unexpectedly unstable. An alternative synthetic route that employed 4-(5-
38]
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ChemMedChem
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4
tetrazoyl)phenylboronic acid also gave the desired tetrazole derivative, but again the isolated
4
0
product proved to be unstable.
Scheme 1. Synthesis of compounds 8-10: (a) NBS (1.1 mol equiv), AcCN, r.t. under Ar; (b) 4-
cyanophenylboronic acid, Pd(PPh , Na CO , dioxane/H O (3:1), 100 ºC under Ar; (c) NBS (2.0 mol equiv),
AcOH, 80 ºC under Ar; (d) 1-naphthylboronic acid (for 8), 2-naphthylboronic acid (for 10), Pd(PPh , Na CO
dioxane/H O (3:1), 100 ºC under Ar; (e) BBr in CH Cl , 0 ºC to r.t. under Ar; (f) NaN (4.0 mol equiv), cat. AcOH,
DMF, 130 ºC under Ar.
3
)
4
2
3
2
3
)
4
2
3
,
2
3
2
2
3
The synthesis of various para-substituted 5-phenyl derivatives structurally similar to 1 and 2
were synthesized as outlined in Scheme 2. The use intermediate B allowed for the preparation of
additional analogs that would not survive the more harsh conditions required for efficient
cleavage of the dimethoxy ethers intermediates that had been previously synthesized from
intermediate A. This intermediate was prepared from 2-fluoro-3-hydroxypyridine by formation
of its 6-iodo derivative and subsequent formation of the 3-((2-methoxyethoxy)methoxy)
derivative using MEM chloride. The 2-fluoro substituent was selectively displaced with t-
butoxide to form the t-butyl ether intermediate. Subsequent reaction of 2-(t-butoxy)-3-((2-
methoxyethoxy)methoxy)-6-iodopyridine with 4-fluorophenylburonic acid provided the 6-(p-
fluorophenyl)- 2-(t-butoxy)-3-((2-methoxyethoxy)methoxy)pyridine, which could be efficiently
brominated using NBS to provide intermediate B. Using this intermediate together with the
appropriate boronic acid or boronate under Suzuki coupling conditions provide the desired 5-
phenyl derivatives of 2-(t-butoxy)-6-(4-fluorophenyl)-3-((2-methoxyethoxy)methoxy)pyridine.
Treatment of these intermediates with trifluoracetic acid in dichloromethane at room temperature
under argon provided the desired para-substituted 5-phenyl derivatives of 6-(p-fluorophenyl)-3-
hydroxypyridin(1H)-2-one, 11-15. Acetylation of the 5-(p-sulfonamidophenyl)-2-(t-butoxy)-6-
(
4-fluorophenyl)-3-((2-methoxyethoxy)methoxy)pyridine intermediate with acetic anhydride in
pyridine with subsequent removal of the removal of the protecting groups was used to prepare
6.
1
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ChemMedChem
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Scheme 2. Synthesis of Compounds 11-16: (a) I
0% dispersed in oil (2.0 mol equiv), THF, -15 ºC followed by MEM-Cl (2.0 mol equiv), r.t. under Ar; (c) KOt-Bu
2.0 mol equiv), AcCN, r.t. under Ar; (d) 4-fluorophenylboronic acid, Pd(PPh , Na CO , dioxane/H O (3:1), 100
ºC under Ar; (e) NBS (2.0 mol equiv), AcCN, r.t. under Ar; (f) 4-carboxyphenylboronic acid (for 11), 4-
2 2 3
(2.0 mol equiv), K CO (2.0 mol equiv), water, r.t.; (b) NaH
6
(
3
)
4
2
3
2
(
(
carboxymethyl)phenylboronic acid (for 12), 4-(1-methyl-tetrazol-5-yl)phenylboronic acid pinacol ester (for 13), 4-
2-methyl-tetrazol-5-yl)phenylboronic acid pinacol ester (for 14), 4-sulfonamidephenylboronic acid (for 15 and 16),
Pd(PPh
3
)
4
, Na
2 3 2 2
CO , dioxane/H O (3:1), 100 ºC under Ar; (g) Ac O, DMAP, pyridine, r.t., under Ar; (h) TFA:
CH Cl
2
2
(1:2), r.t., under Ar.
The preparation of 17 was accomplished as outlined in Scheme 3. Using intermediate B together
with 4-hydroxyphenylboronic acid under Suzuki coupling conditions, the 5-(p-hydroxyphenyl)
intermediate was formed. Conversion of this phenol to its triflate followed by Sonogashira
coupling with (trimethylsilyl)acetylene and removal of the TMS-protecting group provided the
acetylene intermediate, which was converted to the triazole derivative. Removal of the t-butyl
and MEM-protecting groups provided 17.
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ChemMedChem
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Scheme 3. Synthesis of compound 17: (a) 4-hydroxyphenylboronic acid, Pd(PPh
3:1), 100 ºC under Ar; (b) N-phenyl-bis(trifluoromethanesulfonamide) (1.2 mol equiv), Et
CH Cl , 0 ºC to r.t. under Ar; (c) (trimethylsilyl)acetylene, Pd(PPh Cl , CuI, Et N, DMF, 100 ºC under Ar; (d)
CO (2.0 mol equiv), MeOH, r.t. under Ar; (e) TMSN (4.0 mol equiv), CuI (0.1 mol equiv), DMF:MeOH (9:1),
00 ºC under Ar; (f) TFA: CH Cl (1:2), r.t., under Ar.
3
)
4
, Na
2 3 2
CO , dioxane/H O
(
3
N (1.8 mol equiv),
2
2
3
)
2
2
3
K
2
3
3
1
.
2
2
The methods used for the preparation of 18-23 are outlined in Scheme 4. The preparation of
Scheme 4. Synthesis of compounds 18-23: (a) (4-fluorobenzyl)zinc(II) chloride (for 18 and 21), (1-
naphthylmethyl)zinc(II) chloride (for 19 and 12), (2-naphthylmethyl)zinc(II) bromide (for 20 and 23), Johnphos,
Pd(OAc)
2 2 3 3 2 2 3
, K CO , dioxane under Ar; (b) BBr in CH Cl , 0 ºC to r.t. under Ar; (c) NaN (4.0 mol equiv), cat.
AcOH, DMF, 130 ºC under Ar.
the 5-(p-cyanophenyl)-6-arylakyl-3-hydroxypyridin-2(1H)-ones 18-20 was performed using a
Negishi coupling reaction which employed intermediate A together with various organozinc
intermediates. Excellent yields were obtained (80-87%) of the desired 5-(p-cyanophenyl)-6-
arylakyl-2,3-dimethoxypyridines, which upon treatment with BBr
8-20. Treatment of 18-20 with sodium azide in DMF with a catalytic amount of acetic acid
provided the tetrazolyl derivatives 20-23.
3
in methylene chloride yielded
1
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ChemMedChem
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Scheme 5 summarizes the method used for the preparation of 24. Treatment of commercially-
available 5-bromo-3-hydroxypyridin-2(1H)-one with sodium hydride in DMF followed by
MOM-chloride resulted in N,O-protected 5-bromo-3-(methoxymethoxy)-1-
(
methoxymethyl)pyridin-2(1H)-one intermediate as a major product. Suzuki coupling with 4-
fluorophenylboronic acid followed by chlorination by Palau’s chlor gave intermediate 6-chloro-
-(4-fluorophenyl)-3-(methoxymethoxy)-1-(methoxymethyl)pyridin-2(1H)-one. Suzuki
5
coupling together with 4-carboxyphenylboronic acid followed by removal of protective groups
provided compound 24.
Scheme 5. Synthesis of compound 24: (a) NaH 60% dispersed in oil (5.0 mol equiv), DMF, 0 ºC followed by
MOM-Cl (5.0 mol equiv), r.t. under Ar; (b) 4-fluorophenylboronic acid, Pd(PPh
ºC under Ar; (c) Palau’s chlor, CH Cl under Ar; (d) 4-carboxyphenylboronic acid, Pd(PPh
dioxane/H O (3:1), 100 ºC under Ar; (e) 2N HCl/dioxane (1:1), 100 ºC.
3
)
4
, Na
2
CO
3
, dioxane/H
, Na CO
2
O (3:1), 100
2
2
3
)
4
2
3
,
2
The method used for the preparation of 5-arylakyl-6-(p-cyanophenyl)-3-hydroxypyridin-2(1H)-
ones, 25-27, and their tetrazole derivatives, 28-30 is outlined in Scheme 6. 2,3-
Dimethoxypyridine was converted to its 5,6-dibromo derivative using a slight excess of N-
bromosuccinimide in acetic acid in a slight modification of the previously reported procedure.
[
38]
Lithiation of this intermediate with trimethylsilylmethylithium and subsequent reaction with the
appropriate Weinreb amide provided the aryloyl intermediates, which could be converted to 5-
(arylmethyl)-6-bromo-2,3-dimethoxypyridine derivatives using a two-step reduction using
NaBH to form the alcohol with subsequent treatment with triethylsilane and trifluoroacetic acid.
4
The formation of 5-arylakyl-6-(p-cyanophenyl)-2,3-dimetrhoxypyridine derivatives was
accomplished by Suzuki-coupling of these bromopyridines with p-cyanophenylboronic acid.
The approach as outlined in Scheme 6 proved to be much more efficient than earlier attempts,
which attempted to explore the utility of lithiating intermediate A, and then coupling this
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ChemMedChem
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8
intermediate with either an arylaldehyde or a Weinreb amide derivative of p-fluorobenzamide
and the requisite naphthylamides.
Formation of the desired 5-arylakyl-6-(p-cyanophenyl)-3-hydroxypyridin-2(1H)-ones 25-27 was
accomplished by treatment of these 2,3-dimethoxypyridines intermediates with BBr in
3
methylene chloride. The tetrazoyl derivatives 28-30 were prepared by treatment of 25-27 with
sodium azide in DMF with a catalytic amount of acetic acid. The Weinreb amides that were
employed in these syntheses were prepared by reacting N,O-dimethylhydroxylamine with the
requisite acid chloride under conditions similar to those previously reported.4
1
o
Scheme 6. Synthesis of compounds 25-30: Reagents and conditions: (a) NBS (2.2 mol equiv), AcOH, 80 C
o
under Ar; (b) trimethylsilylmethylithium (1.1 mol equiv), toluene, 0 C followed by 4-fluoro-N-methoxy-N-
methylbenzamide (2.0 mol equiv) (for 25) (2.0 mol equiv), N-mehoxy-N-methyl-1-naphthamide (2.0 mol equiv) (for
o
2
Et
Pd(PPh
6), N-methoxy-N-methyl-2-naphthamide (for 27), 0 C under Ar; (c) NaBH
4
(2.0 mol equiv), THF under Ar; (d)
o
3
SiH (3.0 mol equiv), TFA (4.5 mol equiv), 1,2-dichloroethane, 50 C under Ar; (e) 4-cyanophenylboronic acid,
o
3
)
4
, Na
2
CO
3
, dioxane/H
2
O (3:1), 100 ºC under Ar; (f) BBr
3
in CH
2
Cl
2
, 0 C to r.t. under Ar; (g) NaN
3
(4.0
mol equiv), cat. AcOH, DMF under Ar.
RESULTS AND DISCUSSION
The various aryl and arylalkyl substituted 3-hydroxypyridin(1H)-2-ones that were synthesized
were evaluated for the ability to inhibit IAV endonuclease activity. The relative activity of these
compounds was compared to that observed for several analogous compounds that had been
previously synthesized and evaluated.[ Their endonuclease inhibitory activities are provided in
Table 1 and Table 2. The established influenza endonuclease inhibitor L-742,001 has an IC50 of
38]
7
nM and ligand efficiency of 0.361 kcal/(mol·NHA) while the green tea catechin
epigallocatechin gallate has an IC50 of 1 μM and a ligand efficiency of 0.249 kcal/(mol·NHA) in
[
36, 31,]
this assay.
Significant enhancement in inhibition was observed in earlier studies as one converted a p-
cyanophenyl substituent to a p-(5-tetrazoyl)phenyl at the 5-position of 6-(p-fluorophenyl)-3-
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ChemMedChem
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9
hydroxypyridin(1H)-2-one, with 2 being a more potent inhibitor than 1. This trend proved
consistent in when comparing the relative inhibitory activities of 6-(1-naphthyl) (8 and 9), the 6-
p-fluorobenzyl) (18 and 21), 6-[(1-naphthyl)methyl] (19 and 22) and 6-[(2-naphthyl)methyl] (20
(
and 23) derivatives.
The assessment of varied para-substituents on the phenyl substituted at the 5-position of 6-(p-
fluorophenyl)-3-hydroxypyridin (1H)-2-one provides insight into the structure-activity
relationships at this site. Identical activity between 5-(p-(tetrazol-5-yl)phenyl, 2, and the 5-(p-
carboxyphenyl) derivative, 11, of 6-(p-fluorophenyl)-3-hydroxypyridin (1H)-2-one indicates the
importance of having an acidic functional group at this site. An X-ray crystal structure of 11
bound to the endonuclease (Figure 2) showed a similar binding mode (orientation of the
[38]
pyridinone ring) of 11 compared to the previously published 2. The 5-(p-carboxyphenyl) is
situated in a similar position but makes additional interactions Arg124 through two bridging
water molecules.
Replacement of the carboxylic acid of 11 with the methyl ester, 12, resulted in a dramatic loss in
activity. Similarly, loss of the acidic proton on the tetrazole moiety by methylation at either the
1
- or 2- position of 2 as in the case of 13 and 14, respectively, also resulted in a drop in activity.
Neither replacing the carboxylate with a sulfonamide, as in 15, or an acylsulfonamide, as in 16,
resulted in analogs with similar potency as either 2 or 11. Only in the case of the 5-(4-
triazolylphenyl) derivative, 17, was significant potency restored, relative to either 2 or 11.
For these 5-(p-cyanophenyl)- or 5-[p-(5-tetrazoyl)phenyl]-3-hydroxypyridin (1H)-2-ones, the
presence of a (1-naphthyl)methyl substituent at the 6-position (19 and 22) was associated with
greater potency than the similarly substituted p-fluorobenzyl derivatives 18 and 21 or the 2-
naphthylmethyl derivative 10. Both the 6-(1-naphthyl)- and the 6-(2-naphthyl)-5-(p-
cyanophenyl derivatives (19 and 20) were also much less active than their analogous tetrazole
derivatives (22 and 23). These 6-(1-naphthyl)methyl derivatives, however, had similar activity
to the p-fluorophenyl derivatives 1 and 2, as well as the naphthyl analogs, 8 and 9, taking into
account the inherent relative impact of either a p-cyano or a p-5-tetrazoyl moiety.
The structure-activity relationships for aryl and arylalkyl groups at the 5-position of 3-
hydroxypyridin (1H)-2-ones substituted with either 6-(p-cyanophenyl)- or 6-[p-(5-
tetrazoyl)phenyl] were also evaluated. As previously observed for 6 and 7, the tetrazole
derivatives were again more consistently active in this series than the cyano derivatives. This
can also be seen in a comparison of the relative inhibitory activities of the 6-(p-fluorobenzyl) (25
and 28), 6-[(1-naphthyl)methyl] (26 and 29) and 6-[(2-naphthyl)methyl] (27 and 30) derivatives.
The synthesis and evaluation of 6-(4-carboxyphenyl)-5-(p-fluorophenyl)-3-hydroxypyridin (1H)-
[
38]
2
-one 24 did indicate that this derivative, however, was less active as an inhibitor than previously
observed for the structurally-related 6-(p-(5-tetrazoyl)phenyl) analog, 7.
There was another consistency noted in the structure-activity relationships observed for these 5-
(p-cyanophenyl)- or 5-[p-(5-tetrazoyl)phenyl]-3-hydroxypyridin (1H)-2-ones and that observed
for these 6-(p-cyanophenyl)- or 6-[p-(5-tetrazoyl)phenyl]-3-hydroxypyridin((1H)-2-ones.
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1
0
Within this series the presence of a (1-naphthyl)methyl substituent at the 5-position (26 and 29)
was also associated with greater potency than the similarly substituted p-fluorobenzyl derivatives
5 and 28 or the 2-naphthylmethyl derivatives 27 and 30.
2
A X-ray crystal structure of 29 bound to the IAV endonuclease active site (Figure 2B) shows a
similar binding mode as the previously published 7 for the tetrazole but there is significant
rearrangement of the pocket to accommodate the (1-naphthyl)methyl substituent. The tetrazole
placement, as seen previously with compounds 2 and 7, causes a flip in the pyrdinone ring to the
[
38 ]
less favorable orientation seen here.
Although the pyridinone ring in this orientation is less
favorable for 2 and 7, in the case of either 29 or 22 it appears to be slightly more favorable
perhaps due to changes in the water structure near the (1-naphthyl)methyl substituent that the
pyridinone nitrogen forms hydrogen bonds to. The sidechain of Tyr24 rotates 90 degrees and
has 1.5 Å backbone shift to stabilize an edge-to-face stacking interaction with the naphthyl. The
5
-phenyl also has enhanced interaction with Ile38 due to decreased steric clash with the (1-
naphthyl)methyl relative to a fluorophenyl.
Antiviral activity of the compounds was determined using a previously described PR8-mCherry
[
43,44]
assay.
Unfortunately, no antiviral activity except the 11 μM EC50 previously reported for
compound 2 was detected using this cellular assay.[
22]
CONCLUSION:
Our studies on 4-hydroxypyridazin-3(2H)-ones, 5-hydroxypyrimidin-4(3H)-ones, and 3-
hydroxyquinoline-2(1H)ones failed to identify major advantages in potency as IAV
endonuclease inhibitors over the phenyl substituted 3-hydroxypyridin(1H)-2-ones that had been
studied earlier. The intent of the present study was to further examine aryl and arylalkyl
substituted 3-hydroxypyridin(1H)-2-ones to see whether further improvement in potency with
this series of compounds could be achieved. The increased hydrophobic nature of naphthyl
analogs and the increased structural flexibility associated with methylene-linked analogs of both
select phenyl and these naphthyl analogs was viewed as one possible approach wherein both an
increase in activity as IAV endonuclease inhibitors and an improvement in cellular efficacy of
these potential antiviral agents could be achieved. The compounds selected for synthesis,
although synthetically more challenging, were among the more promising based upon our earlier
structure-activity studies. While similar trends in terms of structure-activity could be observed,
no pronounced improvement in potency was realized. More significantly, these select aryl and
arylalkyl substituted 3-hydroxypyridin(1H)-2-ones failed to be efficacious in cellular antiviral
assays.
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ChemMedChem
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1
Table 1. Inhibition Assay of IAV Endonuclease by 5-Subsituted 3-Hydroxypyridin-
(1H)ones.
2
LE
kcal/
mol·NHA)
IC50
(nM)
Compd
X
Y
(
1
2
C≡N
136*
0.409
0.420
1
1*
8
9
C≡N
220
0.351
1
8
0.354
0.330
1
0
C≡N
544
1
1
1
1
2
3
CO
2
H
11
0.455
0.326
COCH
3
125
2
1
98
38
0.331
0.348
1
4
1
1
1
5
6
7
SO
2
NH
2
347
145
0.354
0.335
SO
2
NHCOCH
3
2
5
0.401
0.360
1
8
C≡N
507
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ChemMedChem
10.1002/cmdc.201900084
1
2
1
9
C≡N
C≡N
114
660
0.353
2
2
2
0
1
2
0.314
0.385
2
1
6
6
5
7
0.358
0.328
2
3
*
Data were previously reported.38
Table 2. Inhibition Assay of IAV Endonuclease by 6-Subsituted 3-Hydroxypyridin-
(1H)ones.
2
LE
kcal/
mol·NHA)
IC50
(nM)
Compd
X
Y
(
6
7
C≡N
54*
23*
0.433
0.403
2
4
5
COOH
55
0.415
0.361
2
2
C≡N
484
6
C≡N
173
0.343
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ChemMedChem
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1
3
2
2
7
8
C≡N
250
54
0.335
0.369
2
3
9
12
81
0.362
0.324
0
*
Data were previously reported.38
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ChemMedChem
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4
Figure 2. X-ray crystal structure stereoview images of 11 and 29 with IAV endonuclease
domain. Bound protein is colored purple and apo residues orange. Chelation indicated by black
dashes and hydrogen bonds as blue dashes. Compound omit maps are contoured at 3.0σ (blue).
(A) Compound 11 (blue) bound at the IAV endonuclease active site. (B) Compound 29 (yellow)
bound and 7 (green).
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5
ACKNOWLEDGEMENTS
We gratefully acknowledge financial support from NIH R21 AI119321 (award to EA, EJL, and
LMS). The Bruker Avance III 400 MHz NMR spectrometer used for this study was purchased
with funds from NCRR Grant No. 1S10RR23698-1A1. Mass spectrometry was provided by the
Washington University Mass Spectrometry Resource with support from the NIH National Center
for Research Resources Grant No. P41RR0954. We thank the laboratories of Ann Stock and
Gaetano Montelione for access to equipment used in this study. X-ray data collection was
conducted at the Cornell High Energy Synchrotron Source (CHESS) and the Advanced Photon
Source (APS). CHESS is supported by the NSF & NIH/NIGMS via NSF award DMR-0225180,
and the MacCHESS resource is supported by NIH/NCRR award RR-01646. The Advanced
Photon Source GM/CA 23-ID beam line is funded in whole or in part with Federal funds from
the National Cancer Institute (Y1-CO-1020) and the National Institute of General Medical
Sciences (Y1-GM-1104).
EXPERIMENTAL
Chemistry: General Methods.
All reactions, unless otherwise stated, were done under nitrogen atmosphere. Reaction
monitoring and follow-up were done using aluminum backed Silica G TLC plates with UV254
(Sorbent Technologies), visualizing with ultraviolet light. Flash column chromatography was
done on a Combi Flash Rf Teledyne ISCO using hexane, ethyl acetate, dichloromethane, and
1
13
methanol. The H (400 MHz) and C (100 MHz) NMR spectra were done in CDCl
3
, Methanol-
d
4
, and DMSO-d and recorded on a Bruker Avance III (400 MHz) Multinuclear NMR
6
Spectrometer. Data is expressed in parts per million relative to the residual nondeuterated
solvent signals, spin multiplicities are given as s (singlet), d (doublet), dd (doublet of doublets), t
(triplet), dt (doublet of triplets), q (quartet), m (multiplet), and bs (broad singlet), and coupling
constants (J) are reported in Hertz. Melting points were determined using Mel-temp II apparatus
and are uncorrected. Analytical HPLC was performed on a Shimadzu LC-20AT Prominence
liquid chromatograph using a 150 x 4.6 mm Princeton SPHER-100 RP C18 1000A 5 u column
using 0% water for 2 minutes and a 0-100% water/methanol gradient over a 5 minute period and
5
2
minutes at 100% methanol at a 2.0 ml/minute flow rate monitoring UV absorbance at 254 and
96 nm. Using this method of analysis, the purity of all compounds used in bioassays was
determined to be ≥ 95%. HRMS experiments were conducted by Washington University
Resource for Biomedical and Bioorganic Mass Spectrometry Department of Chemistry.
4
-(5-Hydroxy-2-(naphthalen-1-yl)-6-oxo-1,6-dihydropyridin-3-yl)benzonitrile (8)
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6
4
-(5,6-Dimethoxy-2-(naphthalen-1-yl)pyridin-3-yl)benzonitrile (80 mg, 0.22 mmol) was
o
dissolved in anhydrous DCM (5 mL). The reaction mixture was cooled to 0 C and the 1M in
DCM BBr (2.2 mL, 2.2 mmol) was added. It was then allowed to warm to room temperature
3
and stirred for 24 hours. Then, the solvent was removed under reduced pressure. The resulting
residue was diluted with EtOAc, which was washed with 2N HCl followed by brine. The
organic layer was dried over Na
2
SO followed by concentration under the vacuum. The residue
4
was purified by flash chromatography on silica gel eluting with 0 to 30% EtOAc/Hexane
followed by 0 to 10% MeOH/DCM to provide 4-(5-hydroxy-2-(naphthalen-1-yl)-6-oxo-1,6-
o
1
dihydropyridin-3-yl)benzonitrileas a white solid (32 mg, 45%); m.p. 288-290 C; H NMR (400
MHz, DMSO-d
6
) δ 12.11 (bs, 1H), 9.47 (bs, 1H), 7.96 – 7.93 (m, 2H), 7.60 (d, J = 8Hz, 1H),
1
3
7
.52 – 7.47 (m, 5H), 7.42 (d, J = 7 Hz, 1H), 7.13 (d, J = 8 Hz, 2H), 6.97 (s, 1H); C NMR (100
MHz, DMSO-d
6
) δ 158.0, 146.9, 143.2, 132.9, 132.6, 131.7, 131.5, 131.2, 129.31, 129.25, 129.2,
1
C
28.3, 126.8, 126.1, 125.2, 124.8, 118.5, 117.5, 117.2, 108.8; HRMS (ESI) calculated for
+
22
H
15
N
2
2
O (M+H) 339.1128, found 339.1136.
4
-(5,6-Dimethoxy-2-(naphthalen-1-yl)pyridin-3-yl)benzonitrile
4
-(2-Bromo-5,6-dimethoxypyridin-3-yl)benzonitrile (293 mg, 0.92 mmol), naphthalene-1-
boronic acid (190 mg, 1.10 mmol), Pd(PPh
mmol) were dissolved in a mixture of dioxane (15 mL) and water (5 mL). The air was evacuated
and replaced with N . Then, the reaction mixture was refluxed for 18 hours. After the reaction
was completed, it was cooled to room temperature. It was diluted with EtOAc and washed with
sat. NH Cl followed by brine. The organic layer was dried over Na SO and concentrated under
3
)
4
(106 mg, 0.092 mmol) and Na
2
CO
3
(292 mg, 2.75
2
4
2
4
reduced pressure and the resulting residue was purified by flash chromatography on silica gel
eluting with 0 to 30% EtOAc/Hexane. This afforded 4-(5,6-dimethoxy-2-(naphthalen-1-
o
1
yl)pyridin-3-yl)benzonitrile as a white solid (220 mg, 65%); m.p. 226-228 C; H NMR (400
MHz, CDCl ) δ 7.87 (dd, J = 8 Hz, J = 1 Hz, 1H), 7.81 (d, J = 8 Hz, 2H), 7.48 (td, J = 7 Hz, J =
Hz, 1H), 7.42 –7.39 (m, 1H), 7.37 – 7.32 (m, 3H), 7.21 (s, 1H), 7.17 – 7.14 (m, 3H), 4.06 (s,
3
1
3
1
5
1
3
H), 4.03 (s, 3H); C NMR (100 MHz, CDCl
3
) δ 153.3, 144.6, 143.4, 136.9, 133.7, 132.9, 132.1,
31.8, 129.7, 129.2, 128.6, 128.4, 127.9, 126.1, 125.82, 125.77, 125.0, 119.1, 118.7, 110.3, 56.0,
4.2; HRMS (ESI) calculated for C24
+
H
19
N
2
2
O (M+H) 367.1441, found 367.1450.
4
-(2-Bromo-5,6-dimethoxypyridin-3-yl)benzonitrile
To a solution of 4-(5,6-dimethoxypyridin-3-yl)benzonitrile (603 mg, 2.51 mmol) in AcOH (20
mL) under nitrogen, NBS (893 mg, 5.02 mmol) was added. The reaction mixture was then stirred
o
overnight at 80 C. After the reaction was completed, it was cooled to room temperature. It was
diluted with EtOAc and washed with sat. NaHCO
3
followed by brine. The organic layer was
dried over Na SO and concentrated under reduced pressure and the resulting residue was
2
4
purified by flash chromatography on silica gel eluting with 0 to 20% EtOAc/Hexane. This
afforded 4-(2-bromo-5,6-dimethoxypyridin-3-yl)benzonitrile as a white solid (588 mg, 73%);
o
1
m.p. 151-153 C; H NMR (400 MHz, CDCl ) δ 7.72 (dd, J = 9 Hz, 2H), 7.54 (d, J = 8 Hz, 2H),
3
1
3
6
1
4
.96 (s, 1H), 4.06 (s, 3H), 3.88 (s, 3H); C NMR (100 MHz, CDCl
32.1, 130.4, 129.9, 125.9, 120.4, 118.6, 111.8, 56.3, 54.7.
-(5,6-Dimethoxypyridin-3-yl)benzonitrile
3
) δ 153.4, 143.8, 143.7,
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ChemMedChem
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1
7
5
4
-Bromo-2,3-dimethoxypyridine (692 mg, 3.17mmol), 4-cyanophenyl boronic acid (699 mg,
.76mmol), Pd(PPh (370 mg, 0.32 mmol) and Na CO (1.01 g, 9.51mmol) were dissolved in a
3
)
4
2
3
mixture of dioxane (60 mL) and water (20 mL). The air was evacuated and replaced with N
Then, the reaction mixture was refluxed for 18 hours. After the reaction was completed, it was
cooled to room temperature. It was diluted with EtOAc and washed with sat. NH Cl followed by
brine. The organic layer was dried over Na SO and concentrated under reduced pressure and
2
.
4
2
4
the resulting residue was purified by flash chromatography on silica gel eluting with 0 to 30%
EtOAc/Hexane. This afforded 4-(5,6-dimethoxypyridin-3-yl)benzonitrile as a white solid (603
o
1
mg, 79%); m.p. 109-111 C; H NMR (400 MHz, CDCl
Hz, 2H), 7.64 (d, J = 9 Hz, 2H), 7.22 (d, J = 2 Hz, 1H), 4.07 (s, 3H), 3.96 (s, 3H); C NMR (100
MHz, CDCl ) δ 154.8, 144.3, 142.6, 135.5, 132.7, 128.7, 127.3, 118.7, 115.8, 111.0, 55.8, 54.0.
3
) δ 7.97 (d, J = 2 Hz, 1H), 7.73 (d, J = 8
1
3
3
5
2
-Bromo-2,3-dimethoxypyridine
,3-Dimethoxypyridine (2 g, 14.37 mmol) and NBS (3.84 g, 21.56 mmol) were dissolved in
AcCN (100 mL). It was then stirred for 48 hours at room temperature. After the reaction was
completed, it was diluted with EtOAc and washed with sat. NaHCO followed by brine. The
organic layer was dried over Na SO and concentrated under reduced pressure and the resulting
3
2
4
residue was purified by flash chromatography on silica gel eluting with 50% DCM/Hexane. This
1
afforded 5-bromo-2,3-dimethoxypyridine as colorless oil (1.36 g, 43%); H NMR (400 MHz,
1
3
CDCl
MHz, CDCl
3
) δ 7.77 (d, J = 2 Hz, 1H), 7.13 (d, J = 2 Hz, 1H), 3.99 (s, 3H), 3.87 (s, 3H); C NMR (100
) δ 153.5, 144.6, 137.4, 120.2, 111.1, 56.0, 53.9.
3
4
4
-(5-Hydroxy-2-(naphthalen-2-yl)-6-oxo-1,6-dihydropyridin-3-yl)benzonitrile (9)
-(5,6-Dimethoxy-2-(naphthalen-2-yl)pyridin-3-yl)benzonitrile (100 mg, 0.27 mmol) was
o
dissolved in anhydrous DCM (5 mL). The reaction mixture was cooled to 0 C and the 1M in
DCM BBr (2.7 mL, 2.7 mmol) was added. It was then allowed to warm to room temperature
3
and stirred for 24 hours. Then, the solvent was removed under reduced pressure. The resulting
residue was diluted with EtOAc, which was washed with 2N HCl followed by brine. The
organic layer was dried over Na
2
SO followed by concentration under the vacuum. The residue
4
was purified by flash chromatography on silica gel eluting with 0 to 30% EtOAc/Hexane
followed by 0 to 10 % MeOH/DCM to provide 4-(5-hydroxy-2-(naphthalen-2-yl)-6-oxo-1,6-
1
dihydropyridin-3-yl)benzonitrileas a white solid (32 mg, 35%); m.p. 262-264 ; H NMR (400
MHz, DMSO-d
6
) δ 12.13 (bs, 1H), 9.49 (bs, 1H), 7.88 – 7.85 (m, 3H), 7.77 (d, J = 8 Hz, 1H),
7
1
1
.64 – 7.62 (m, 2H), 7.55 – 7.54 (m, 2H), 7.25 (d, J = 8 Hz, 2H), 7.12 (d, J = 8 Hz, 1H), 6.92 (s,
1
3
H); C NMR (100 MHz, DMSO-d
6
) δ 158.2, 146.6, 143.5, 132.4, 132.0, 131.5, 131.4, 130.4,
29.5, 128.8, 128.7, 128.2, 127.5, 127.43, 127.37, 126.9, 126.5, 118.7, 117.9, 109.0; HRMS
+
(ESI) calculated for C22
H
15
N
2
O (M+H) 339.1128, found 339.1139.
2
4
-(5,6-Dimethoxy-2-(naphthalen-2-yl)pyridin-3-yl)benzonitrile
4
-(2-Bromo-5,6-dimethoxypyridin-3-yl)benzonitrile(300 mg, 0.97mmol), naphthalene-2-boronic
acid (251 mg, 1.46 mmol), Pd(PPh
3
)
4
(112 mg, 0.097 mmol) and Na
2
CO (310 mg, 2.92 mmol)
3
were dissolved in a mixture of dioxane (30 mL) and water (10 mL). The air was evacuated and
replaced with N
2
. Then, the reaction mixture was refluxed for 18 hours. After the reaction was
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ChemMedChem
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8
completed, it was cooled to room temperature. It was diluted with EtOAc and washed with sat.
NH Cl followed by brine. The organic layer was dried over Na SO and concentrated under
4
2
4
reduced pressure and the resulting residue was purified by flash chromatography on silica gel
eluting with 0 to 30% EtOAc/Hexane. This afforded 4-(5,6-dimethoxy-2-(naphthalen-2-
o
1
yl)pyridin-3-yl)benzonitrile as a white solid (357 mg, 100%); m.p. 182-184 C; H NMR (400
MHz, CDCl ) δ 7.84 (d, J = 1 Hz, 1H), 7.82 – 7.80 (m, 1H), 7.73 – 7.70 (m, 2H), 7.55 (d, J = 8
Hz, 2H), 7.49 – 7.46 (m, 2H), 7.41 (dd, J = 9 Hz, J = 2 Hz, 1H), 7.35 (d, J = 8 Hz, 2H), 7.11 (s,
3
1
3
1
1
5
H), 4.18 (s, 3H), 3.99 (s, 3H); C NMR (100 MHz, CDCl
3
) δ 153.6, 145.2, 144.4, 143.3, 136.5,
33.1, 132.7, 132.2, 129.5, 128.3, 127.7, 127.6, 127.5, 127.4, 126.4, 126.2, 119.8, 118.8, 110.6,
6.1, 54.0; HRMS (ESI) calculated for C24
+
H
19
N
2
2
O (M+H) 367.1441, found 367.1449.
5
-(4-(1H-Tetrazol-5-yl)phenyl)-3-hydroxy-6-(naphthalen-1-yl)pyridin-2(1H)-one (10)
4
-(5-Hydroxy-2-(naphthalen-1-yl)-6-oxo-1,6-dihydropyridin-3-yl)benzonitrile (60 mg, 0.18
mmol) and NaN
3
(46 mg, 0.71 mmol) were dissolved in anhydrous DMF (1 mL). The reaction
mixture was treated with catalytic amount of acetic acid. It was sealed and then it was heated at
o
1
30 C for overnight. The reaction was cooled to room temperature and gave brownish
suspension. After the completion of the reaction, the solvent was re- moved under vacuum.
Addition of 2N HCl and stirring produced a solid, which was filtered to give the pure product (37
o
1
mg, 55% yield); m.p. 223-225 C; H NMR (400 MHz, DMSO-d
6
) δ 12.07 (bs, 1H), 9.43 (bs,
1
7
1
1
H), 7.95 – 7.92 (m, 2H), 7.65 (d, J = 8 Hz, 2H), 7.62 (d, J = 2Hz, 1H), 7.50 – 7.45 (m, 4H),
1
3
.18 (d, J = 8 Hz, 2H), 7.01 (s, 1H); C NMR (100 MHz, DMSO-d
6
) δ 158.0, 146.7, 141.2,
32.9, 132.2, 131.6, 129.4, 129.2, 129.1, 128.3, 126.8, 126.4, 126.1, 125.2, 124.9, 121.8, 118.1,
+
17.6; HRMS (ESI) calculated for C22
H
16
N
5
O
2
(M+H) 382.1299, found 382.1300.
4
-(2-(4-Fluorophenyl)-5-hydroxy-6-oxo-1,6-dihydropyridin-3-yl)benzoic acid (11)
To a solution of 4-(6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-
yl)benzoic acid (75 mg, 0.16 mmol) in anhydrous DCM (2 mL) under nitrogen, TFA (1 mL) was
added. It was then stirred for 3 hours at room temperature. After removal of solvent, 4-(2-(4-
fluorophenyl)-5-hydroxy-6-oxo-1,6-dihydropyridin-3-yl)benzoic acid was crystallized as a white
o
1
solid in EtOH:Et
2
O (1:2) (39 mg, 75%); dec. 301-303 C; H NMR (400 MHz, DMSO-d
6
) δ
1
7
1
1
2.82 (bs, 1H), 12.00 (bs, 1H), 9.37 (bs, 1H), 7.76 (d, J = 8 Hz, 2H), 7.22 – 7.18 (m, 2H), 7.15 –
1
3
.10 (m, 4H), 6.85 (s, 1H); C NMR (100 MHz, DMSO-d
6
) δ 167.0, 161.9 (JC,F= 245 Hz),
58.0, 146.4, 142.9, 133.0, 132.2 (JC,F= 9 Hz), 130.1 (JC,F= 3 Hz), 129.6, 129.1, 128.6, 118.1,
1
9
17.0, 115.0 (JC,F= 22 Hz); F NMR (376 MHz, DMSO-d ) δ -113.0; HRMS (ESI) calculated for
6
+
C
18
H
13FNO (M+H) 326.0823, found 326.0812.
4
4
-(6-(t-Butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-yl)benzoic acid 3-
Bromo-6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridine (200 mg, 0.47
mmol), 4-(carboxyphenyl) boronic acid (118 mg, 0.71 mmol), Pd(PPh (58 mg, 0.05 mmol)
and Na CO (149 mg, 1.41 mmol) were dissolved in a mixture of dioxane (15 mL) and water (5
mL). The air was evacuated and replaced with N . Then, the reaction mixture was refluxed for 6
hours. After the reaction was completed, it was cooled to room temperature. It was diluted with
EtOAc and washed with sat. NH Cl followed by brine. The organic layer was dried over Na SO
)
3 4
2
3
2
4
2
4
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ChemMedChem
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9
and concentrated under reduced pressure and the resulting residue was purified by flash
chromatography on silica gel eluting with 0 to 50% EtOAc/Hexane. This afforded 4-(6-(t-
butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-yl)benzoic acid as a white
o
1
solid (109 mg, 49%); m.p. 142-144 C; H NMR (400 MHz, CDCl
3
) δ 8.03 (d, J = 8 Hz, 2H),
7
3
.44 (s, 1H), 7.31 – 7.29 (m, 4H), 6.93 (t, J = 9 Hz, 2H), 5.36 (s, 2H), 3.96 – 3.94 (m, 2H), 3.63 –
1
3
.61 (m, 2H), 3.40 (s, 3H), 1.71 (s, 9H); C NMR (100 MHz, CDCl ) δ 171.4, 162.2 (JC,F= 246
3
Hz), 154.1, 145.8, 145.5, 140.9, 135.7, 131.6 (JC,F= 8 Hz), 130.3, 129.9, 127.61, 127.57 127.4,
1
9
1
14.8 (JC,F= 21 Hz), 94.8, 80.8, 71.6, 68.0, 59.0, 28.9; F NMR (376 MHz, CDCl ) δ -115.1;
3
+
HRMS (ESI) calculated for C26
H
29FNO (M+H) 470.1973, found 470.1974.
6
3
-Bromo-6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridine
To a solution of 2-(t-butoxy)-6-(4-fluorophenyl)-3-((2-methoxyethoxy)methoxy)pyridine (4 g,
1.45 mmol) in AcCN (100 mL) under nitrogen, NBS (4.08 g, 22.90 mmol) in AcCN (100mL)
1
was added over 30 minutes. The reaction mixture was then stirred for 3 hours at room
temperature. After the reaction was completed, it was diluted with EtOAc and washed with sat.
NaHCO
3
followed by brine. The organic layer was dried over Na
2
SO and concentrated under
4
reduced pressure and the resulting residue was purified by flash chromatography on silica gel
eluting with 0 to 10% EtOAc/Hexane. This afforded 3-bromo-6-(t-butoxy)-2-(4-fluorophenyl)-
o
1
5
-((2-methoxyethoxy)methoxy)pyridine as a white solid (3.92 g, 80%); m.p. 67-69 C H NMR
(
400 MHz, CDCl ) δ 7.70 – 7.66 (m, 2H), 7.61 (s, 1H), 7.10 (t, J = 9Hz, 2H), 5.28 (s, 2H), 3.90 –
3
1
3
3
1
1
.88 (m, 2H), 3.61 – 3.58 (m, 2H), 3.41 (s, 3H), 1.60 (s, 9H); C NMR (100 MHz, CDCl
3
) δ
62.5 (JC,F= 245 Hz), 153.3, 145.8, 141.4, 135.5, 131.3 (JC,F= 8 Hz), 129.6, 114.6 (JC,F= 22 Hz),
1
9
08.4, 94.8, 81.0, 71.5, 68.2, 59.1, 28.7; F NMR (376 MHz, CDCl )δ -113.8; HRMS (ESI)
3
+
calculated for C19
H
24BrFNO (M+H) 428.0867, found 428.0867.
4
2
-(t-Butoxy)-6-(4-fluorophenyl)-3-((2-methoxyethoxy)methoxy)pyridine
2
-(t-Butoxy)-6-iodo-3-((2-methoxyethoxy)methoxy)pyridine (5.10 g, 13.38 mmol), 4-
fluorophenyl boronic acid (2.81 g, 20.07 mmol), Pd(PPh
3
)
4
(1.55 g, 1.34 mmol) and Na
2
CO
3
(4.25 g, 40.14 mmol) were dissolved in a mixture of dioxane (45 mL) and water (15 mL). The
air was evacuated and replaced with N . Then, the reaction mixture was refluxed for 18 hours.
2
After the reaction was completed, it was cooled to room temperature. It was diluted with EtOAc
and washed with sat. NH Cl followed by brine. The organic layer was dried over Na SO and
concentrated under reduced pressure and the resulting residue was purified by flash
chromatography on silica gel eluting with 0 to 10% EtOAc/Hexane. This afforded 2-(t-butoxy)-
4
2
4
1
6
-(4-fluorophenyl)-3-((2-methoxyethoxy)methoxy)pyridine as yellowish oil (4.00 g, 86%); H
NMR (400 MHz, CDCl ) δ 7.92 – 7.89 (m, 2H), 7.38 (d, J = 8 Hz, 1H), 7.19 (d, J = 8 Hz, 1H),
.11 (t, J = 9 Hz, 2H), 5.29 (s, 2H), 3.90-3.88 (m, 2H), 3.59 – 3.57 (m, 2H), 3.38 (s, 3H), 1.69 (s,
3
7
9
1
3
H); C NMR (100 MHz, CDCl ) δ 162.9 (JC,F= 246 Hz), 154.5, 146.3, 141.3, 135.3 (JC,F= 3
3
1
9
Hz), 127.9 (JC,F= 9 Hz), 125.5, 115.4 (JC,F = 22 Hz), 112.2, 94.7, 80.2, 71.6, 68.0, 59.0, 28.8; F
NMR (376 MHz, CDCl )δ -114.7; HRMS (ESI) calculated for C19
Na (M+Na)+
72.1582, found 372.1581.
3
H24FNO
4
3
2
-(t-Butoxy)-6-iodo-3-((2-methoxyethoxy)methoxy)pyridine
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ChemMedChem
10.1002/cmdc.201900084
2
0
To a solution of 2-fluoro-6-iodo-3-((2-methoxyethoxy)methoxy)pyridine (5.31 g, 16.23 mmol) in
THF (160 mL) under nitrogen, potassium t-butoxide (3.64 g, 32.46 mmol) in DMF (10 mL) was
added over 30 min. The reaction mixture was then stirred for 15 minutes at room temperature.
After the reaction was complete, it was diluted with EtOAc and washed with water followed by
brine. The organic layer was dried over Na
2
SO and concentrated under reduced pressure and
4
the resulting residue was purified by flash chromatography on silica gel eluting with 0 to 10%
EtOAc/Hexane. This afforded 2-(t-butoxy)-6-iodo-3-((2-methoxyethoxy)methoxy)pyridineas
1
colorless oil (5.10 g, 82%); H NMR (400 MHz, CDCl
3
) δ 7.13 (d, J = 8 Hz, 1H), 6.99 (d, J = 8
1
3
Hz, 1H), 5.20 (s, 2H), 3.84 – 3.81 (m, 2H), 3.54 – 3.52 (m, 2H), 3.36 (s, 3H), 1.58 (s, 9H); C
NMR (100 MHz, CDCl ) δ 154.1, 142.2, 126.74, 126.68, 101.6, 94.6, 81.5, 71.5, 68.0, 59.0,
8.3; HRMS (ESI) calculated for C13
3
+
2
H
21INO (M+H) 382.0510, found 382.0510.
4
2
-Fluoro-6-iodo-3-((2-methoxyethoxy)methoxy)pyridine
To a solution of 2-fluoro-6-iodopyridin-3-ol (4.01 g, 16.78 mmol) in THF (170 mL) under
o
nitrogen, NaH, 60% dispersion in mineral oil (1.34 g, 33.56 mmol) was added at -15 C
o
(
ice/acetone). The reaction mixture was then stirred for 30 minutes at 0 C. 2-
Methoxyethoxymethyl chloride (3.83 mL, 33.56 mmol) was added to the mixture, and it was
stirred for 3 hours at room temperature. After the reaction was completed, it was diluted with
EtOAc and washed with water followed by brine. The organic layer was dried over Na
concentrated under reduced pressure and the resulting residue was purified by flash
2
SO and
4
chromatography on silica gel eluting with 0 to 10% EtOAc/Hexane. This afforded 2-fluoro-6-
1
iodo-3-((2-methoxyethoxy)methoxy)pyridineas colorless oil (5.31 g, 97%); H NMR (400 MHz,
CDCl ) δ 7.11 (d, J = 8 Hz, 1H), 6.90 (dd, J = 10 Hz, J = 8 Hz, 1H), 4.90 (s, 2H), 3.46 – 3.44 (m,
3
1
3
2
1
5
3
H), 3.15 – 3.13 (m 2H), 2.96 (s, 3H); C NMR (100 MHz, CDCl
3
) δ 152.7 (JC,F= 244 Hz),
40.4 (JC,F= 24 Hz), 132.9 (JC,F= 5 Hz), 128.3 (JC,F= 4 Hz), 100.1 (JC,F= 12 Hz), 94.5, 71.4, 68.4,
19
12IFNO
(M+H)+
9.0; F NMR (376 MHz, CDCl
27.9840, found 327.9833.
3
)δ -80.5; HRMS (ESI) calculated for C
9
H
3
2
-Fluoro-6-iodopyridin-3-ol
To a solution of 2-fluoro-3-hydroxypyridin (2.5 g, 22.10 mmol) in water (125 mL), I
2
(5.61g,
4
4.20 mmol) followed by K CO (6.11 g, 44.20 mmol) were added. The reaction mixture was
2
3
then stirred for 3 hours at room temperature. After the reaction was completed, it was diluted
with EtOAc and washed with 2N HCl, 10% sodium thiosulfate followed by brine. The organic
layer was dried over Na
2
SO and concentrated under reduced pressure and the resulting residue
4
was purified by flash chromatography on silica gel eluting with 0 to 50% EtOAc/Hexane. This
o
1
afforded 2-fluoro-6-iodopyridin-3-ol as a white solid (4.01 g, 76%); m.p. 117-119 C; H NMR
1
3
(
400 MHz, CDCl
MHz, CDCl ) δ 151.7 (JC,F= 239 Hz), 139.9 (JC,F= 27 Hz), 133.2 (JC,F= 5 Hz), 128.6 (JC,F= 5
Hz), 96.7 (JC,F= 12 Hz); F NMR (376 MHz, CDCl
3
) δ 7.27 (d, J = 8 Hz, 1H), 7.01 (dd, J = 10 Hz, J = 8 Hz, 1H); C NMR (100
3
19
3
)δ -85.8; HRMS (ESI) calculated for
+
C
5
H FINO (M+H) 239.9316, found 239.9316.
4
Methyl 4-(2-(4-fluorophenyl)-5-hydroxy-6-oxo-1,6-dihydropyridin-3-yl)benzoate (12)
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ChemMedChem
10.1002/cmdc.201900084
2
1
To a solution of methyl 4-(6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-
methoxyethoxy)methoxy)pyridin-3-yl)benzoate (75 mg, 0.16 mmol) in anhydrous DCM (2 mL)
under nitrogen, TFA (1 mL) was added. It was then stirred for 3 hours at room temperature.
After removal of solvent, methyl 4-(2-(4-fluorophenyl)-5-hydroxy-6-oxo-1,6-dihydropyridin-3-
yl)benzoate was crystallized as a white solid in EtOH:Et
2
O (1:2) (54 mg, 100%); m.p. 160-162
o
1
C; H NMR (400 MHz, DMSO-d
.18 (m, 2H), 7.16 (d, J = 8 Hz, 2H), 7.12 (t, J = 9 Hz, 2H), 6.86 (s, 1H), 3.82 (s, 3H); C NMR
100 MHz, DMSO-d ) δ 165.9, 161.9 (JC,F= 245 Hz), 158.0, 146.4, 143.3, 133.1, 132.2 (JC,F= 8
Hz), 130.1, 129.8, 129.0, 127.5, 118.0, 116.9, 115.1 (JC,F= 21 Hz), 52.0; F NMR (376 MHz,
6
) δ 12.03 (bs, 1H), 9.42 (bs, 1H), 7.78 (d, J= 8 Hz, 2H), 7.22 –
1
3
7
(
6
19
+
DMSO-d
6
) δ-112.9;HRMS (ESI) calculated for C19
H15FNO (M+H) 340.0980, found 340.0965.
4
Methyl 4-(6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-
yl)benzoate
3
-Bromo-6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridine (200mg, 0.47
mmol), 4-(methoxycarbonylphenyl) boronic acid (128 mg, 0.71 mmol), Pd(PPh (58 mg, 0.05
mmol) and Na CO (149 mg, 1.41 mmol) were dissolved in a mixture of dioxane (15 mL) and
water (5 mL). The air was evacuated and replaced with N . Then, the reaction mixture was
refluxed for 6 hours. After the reaction was completed, it was cooled to room temperature. It
was diluted with EtOAc and washed with sat. NH Cl followed by brine. The organic layer was
dried over Na SO and concentrated under reduced pressure and the resulting residue was
)
3 4
2
3
2
4
2
4
purified by flash chromatography on silica gel eluting with 0 to 50% EtOAc/Hexane. This
afforded methyl 4-(6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-
1
yl)benzoate as colorless oil (116 mg, 51%); H NMR (400 MHz, CDCl
3
) δ 7.96 (d, J = 8 Hz,
2
3
H), 7.42 (s, 1H), 7.29 – 7.24 (m, 4H), 6.91 (t, J = 9 Hz, 2H), 5.34 (s, 2H), 3.94 – 3.75 (m, 5H),
1
3
.61 – 3.59 (m, 2H), 3.39 (s, 3H), 1.70 (s, 9H); C NMR (100 MHz, CDCl
3
) δ 166.9, 162.2
(
1
J
C,F= 246 Hz), 154.0, 145.5, 144.8, 140.9, 137.3 (JC,F= 3 Hz), 131.6 (JC,F= 8 Hz), 129.7, 129.6,
19
28.5, 127.7, 127.5, 114.7 (JC,F= 21 Hz), 94.8, 80.7, 71.6, 68.0, 59.0, 52.1, 28.0; F NMR (376
+
MHz, CDCl
3
) δ -114.7; HRMS (ESI) calculated for C27
H
31FNO (M+H) 484.2130, found
6
4
84.2130.
6
-(4-Fluorophenyl)-3-hydroxy-5-(4-(1-methyl-1H-tetrazol-5-yl)phenyl)pyridin-2(1H)-one (13)
To a solution of 2-(t-butoxy)-6-(4-fluorophenyl)-3-((2-methoxyethoxy)methoxy)-5-(4-(1-methyl-
H-tetrazol-5-yl)phenyl)pyridine (100 mg, 0.20 mmol) in anhydrous DCM (2 mL) under
1
nitrogen, TFA (1 mL) was added. It was then stirred for 2 hours at room temperature. After
removal of solvent, 6-(4-fluorophenyl)-3-hydroxy-5-(4-(1-methyl-1H-tetrazol-5-
yl)phenyl)pyridin-2(1H)-one was crystallized as a white solid in Water:MeOH (2:1) (66 mg,
o
1
9
=
0%);m.p. 137-139 C; H NMR (400 MHz, CDCl
8 Hz, 2H), 7.20 – 7.17 (m, 2H), 7.05 (s, 1H), 6.99 (t, J = 8 Hz, 2H), 4.16 (s, 3H); C NMR
100 MHz, CDCl +MeOD) δ 162.9 (JC,F= 250 Hz), 158.6, 154.0, 145.9, 141.1, 132.9, 131.4
C,F= 8 Hz), 130.4, 129.6, 128.7, 122.2, 118.9, 118.8, 116.0 (JC,F= 22 Hz), 35.1; F NMR (376
3
+MeOD) δ 7.62 (d, J = 7 Hz, 2H), 7.26 (d, J
1
3
(
(
3
19
J
+
MHz, CDCl
3
+MeOD) δ -111.0;HRMS (ESI) calculated for C19
H15FN
5
2
O (M+H) 364.1204,
found 364.1195.
This article is protected by copyright. All rights reserved.

ChemMedChem
10.1002/cmdc.201900084
2
2
2
-(t-Butoxy)-6-(4-fluorophenyl)-3-((2-methoxyethoxy)methoxy)-5-(4-(1-methyl-1H-tetrazol-5-
yl)phenyl)pyridine
-Bromo-6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridine (197 mg, 0.46
mmol), 1-methyl-5-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl-1H-tetrazole (146
mg, 0.51 mmol), Pd(PPh (58 mg, 0.05 mmol) and Na CO (146 mg, 1.38 mmol) were
dissolved in a mixture of dioxane (15 mL) and water (5 mL). The air was evacuated and
replaced with N . Then, the reaction mixture was refluxed for 3 hours. After the reaction was
completed, it was cooled to room temperature. It was diluted with EtOAc and washed with sat.
NH Cl followed by brine. The organic layer was dried over Na SO and concentrated under
3
3
)
4
2
3
2
4
2
4
reduced pressure and the resulting residue was purified by flash chromatography on silica gel
eluting with 0 to 50% EtOAc/Hexane. This afforded 2-(t-butoxy)-6-(4-fluorophenyl)-3-((2-
methoxyethoxy)methoxy)-5-(4-(1-methyl-1H-tetrazol-5-yl)phenyl)pyridine as a white solid (100
o
1
mg, 43%); m.p. 108-110 C; H NMR (400 MHz, CDCl
3
) δ 7.50 (d, J = 8 Hz, 2H), 7.20 (d, J = 8
Hz, 2H), 7.14 – 7.11 (m, 2H), 7.10 (s, 1H), 6.75 (t, J = 9 Hz, 2H), 5.17 (s, 2H), 4.02 (s, 3H), 3.77
1
3
–
1
1
3.75 (m, 2H), 3.44 – 3.41 (m, 2H), 3.21 (s, 3H), 1.52 (s, 9H); C NMR (100 MHz, CDCl ) δ
3
62.2 (JC,F= 246 Hz), 154.2, 154.1, 145.5, 143.4, 141.1, 135.7 (JC,F= 3 Hz), 131.6 (JC,F= 8 Hz),
30.6, 128.6, 127.4, 126.9, 122.0, 114.8 (JC,F= 21 Hz), 94.8, 80.9, 71.6, 68.0, 59.0, 35.1, 28.9; F
1
9
+
NMR (376 MHz, CDCl
found 508.2355.
3
)δ -114.5; HRMS (ESI) calculated for C27
H31FN
5
O
4
(M+H) 508.2355,
6
-(4-Fluorophenyl)-3-hydroxy-5-(4-(2-methyl-2H-tetrazol-5-yl)phenyl)pyridin-2(1H)-one (14)
To a solution of 2-(t-butoxy)-6-(4-fluorophenyl)-3-((2-methoxyethoxy)methoxy)-5-(4-(2-methyl-
H-tetrazol-5-yl)phenyl)pyridine (109 mg, 0.21 mmol) in anhydrous DCM (2 mL) under
2
nitrogen, TFA (1 mL) was added. It was then stirred for 3 hours at room temperature. After
removal of solvent, 6-(4-fluorophenyl)-3-hydroxy-5-(4-(2-methyl-2H-tetrazol-5-
yl)phenyl)pyridin-2(1H)-one was crystallized as a white solid in Water:MeOH (2:1) (64 mg,
o
1
8
7
4%); m.p. 244-245 C; H NMR (400 MHz, CDCl
.13 (m, 4H), 7.04 (s, 1H), 6.94 (t, J = 9 Hz, 2H), 4.35 (s, 3H); C NMR (100 MHz,
+MeOD) δ 164.8, 162.8 (JC,F= 248 Hz), 158.6, 145.7, 139.8, 132.6, 131.4 (JC,F= 8 Hz),
3
+MeOD) δ 7.94 (d, J = 8 Hz, 2H), 7.17 –
1
3
CDCl
1
CDCl
3
19
30.1, 129.8, 126.8, 126.0, 119.6, 119.4, 115.8 (JC,F= 21 Hz), 39.4; F NMR (376 MHz,
+
3
+MeOD) δ -111.4; HRMS (ESI) calculated for C19
H15FN
5
O (M+H) 364.1204, found
2
3
64.1197.
2
-(t-Butoxy)-6-(4-fluorophenyl)-3-((2-methoxyethoxy)methoxy)-5-(4-(2-methyl-2H-tetrazol-5-
yl)phenyl)pyridine
-Bromo-6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridine (193 mg, 0.45
mmol), 2-methyl-5-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl-2H-tetrazole (195
mg, 0.68 mmol), Pd(PPh (58 mg, 0.05 mmol) and Na CO (143 mg, 1.35 mmol) were
dissolved in a mixture of dioxane (15 mL) and water (5 mL). The air was evacuated and
replaced with N . Then, the reaction mixture was refluxed for 3 hours. After the reaction was
completed, it was cooled to room temperature. It was diluted with EtOAc and washed with sat.
NH Cl followed by brine. The organic layer was dried over Na SO and concentrated under
3
3
)
4
2
3
2
4
2
4
reduced pressure and the resulting residue was purified by flash chromatography on silica gel
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ChemMedChem
10.1002/cmdc.201900084
2
3
eluting with 0 to 30% EtOAc/Hexane. This afforded 2-(t-butoxy)-6-(4-fluorophenyl)-3-((2-
methoxyethoxy)methoxy)-5-(4-(2-methyl-2H-tetrazol-5-yl)phenyl)pyridine as a white solid (199
o
1
mg, 87%); m.p. 97-99 C; H NMR (400 MHz, CDCl
3
) δ 8.05 (d, J = 8 Hz, 2H), 7.44 (s, 1H),
7
3
.35 – 7.29 (m, 2H), 6.91 (t, J = 9 Hz, 2H), 5.35 (s, 2H), 4.41 (s, 3H), 3.95 – 3.93 (m, 2H), 3.62 –
1
3
.59 (m, 2H), 3.39 (s, 3H), 1.70 (s, 9H); C NMR (100 MHz, CDCl ) δ 165.0, 162.1 (JC,F= 246
3
Hz), 153.9, 145.4, 142.1, 140.9, 135.9 (JC,F= 3 Hz), 131.6 (JC,F= 8 Hz), 130.3, 127.82, 127.79,
1
9
1
26.8, 122.0, 114.7 (JC,F= 21 Hz), 94.8, 80.9, 71.6, 68.0, 59.0, 35.1, 28.9; F NMR (376 MHz,
+
CDCl
3
)δ -115.0; HRMS (ESI) calculated for C27
H31FN
5
O (M+H) 508.2355, found 508.2355.
4
4
-(2-(4-Fluorophenyl)-5-hydroxy-6-oxo-1,6-dihydropyridin-3-yl)benzenesulfonamide (15)
To a solution of 4-(6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-
yl)benzenesulfonamide (100 mg, 0.20 mmol) in anhydrous DCM (2 mL) under nitrogen, TFA (1
mL) was added. It was then stirred for 3 hours at room temperature. After removal of solvent,
4
-(2-(4-fluorophenyl)-5-hydroxy-6-oxo-1,6-dihydropyridin-3-yl)benzenesulfonamide was
o
1
crystallized as a white solid in Water:MeOH (2:1) (62 mg, 87%); m.p. 176-178 C; H NMR
400 MHz, DMSO-d ) δ 12.02 (bs, 1H), 9.42 (bs, 1H), 7.53 (d, J = 8 Hz, 2H), 7.21 – 7.17 (m,
H), 7.14 (d, J = 8 Hz, 2H), 7.10 (t, J = 9 Hz, 2H), 6.82 (s, 1H); C NMR (100 MHz, DMSO-d
δ 161.9 (JC,F= 245 Hz), 157.9, 146.3, 142.3, 139.3, 133.1, 132.2 (JC,F= 8 Hz), 129.8, 126.2,
(
2
6
1
3
6
)
1
9
1
25.5, 118.0, 116.4, 115.1 (JC,F= 21 Hz); F NMR (376 MHz, DMSO-d ) δ -112.8; HRMS (ESI)
6
+
calculated for C17
H14FN
2
O S (M+H) 361.0653, found 361.0645.
4
4
-(6-(t-Butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-
yl)benzenesulfonamide
-Bromo-6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridine (200 mg, 0.47
mmol), 4-boronbenzene sulfonamide (143 mg, 0.71 mmol), Pd(PPh (58 mg, 0.05 mmol) and
Na CO (149 mg, 1.41 mmol) were dissolved in a mixture of dioxane (15 mL) and water (5 mL).
The air was evacuated and replaced with N . Then, the reaction mixture was refluxed for 3
hours. After the reaction was completed, it was cooled to room temperature. It was diluted with
EtOAc and washed with sat. NH Cl followed by brine. The organic layer was dried over Na SO
3
)
3 4
2
3
2
4
2
4
and concentrated under reduced pressure and the resulting residue was purified by flash
chromatography on silica gel eluting with 0 to 50% EtOAc/Hexane. This afforded 4-(6-(t-
butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-yl)benzenesulfonamide as
1
colorless oil (225 mg, 95%); H NMR (400 MHz, CDCl
3
) δ 7.81 (d, J = 8 Hz, 2H), 7.37 (s, 1H),
7
2
2
1
.29 (d, J = 9 Hz, 2H), 7.27 – 7.23 (m, 2H), 6.91 (t, J = 9 Hz, 2H), 5.22 (s, 2H), 3.92 – 3.90 (m,
1
3
H), 3.59 – 3.57 (m, 2H), 3.35 (s, 3H), 1.68 (s, 9H); C NMR (100 MHz, CDCl
3
) δ 162.2 (JC,F=
46 Hz), 154.1, 145.5, 144.8, 141.0, 140.3, 135.5 (JC,F= 4 Hz), 131.6 (JC,F= 8 Hz), 130.3, 127.4,
1
9
26.7, 126.5, 114.9 (JC,F= 21 Hz), 94.8, 81.0, 71.5, 68.0, 58.9, 28.8; F NMR (376 MHz,
+
CDCl
3
)δ -114.3; HRMS (ESI) calculated for C25
H30FN
2
O S (M+H) 505.1803, found 505.1803.
6
N-((4-(2-(4-Fluorophenyl)-5-hydroxy-6-oxo-1,6-dihydropyridin-3-
yl)phenyl)sulfonyl)acetamide (16)
To a solution of N-((4-(6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-
3
-yl)phenyl)sulfonyl)acetamide (50 mg, 0.09 mmol) in anhydrous DCM (2 mL) under nitrogen,
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ChemMedChem
10.1002/cmdc.201900084
2
4
TFA (1 mL) was added. It was then stirred for 3 hours at room temperature. After removal of
solvent, N-((4-(2-(4-fluorophenyl)-5-hydroxy-6-oxo-1,6-dihydropyridin-3-
yl)phenyl)sulfonyl)acetamidewas crystallized as a white solid in EtOH:Et O (1:2) (33 mg, 92%);
) δ 12.04 (bs, 2H), 9.45 (bs, 1H), 7.73 (d, J = 8
Hz, 2H), 7.26 (d, J = 8 Hz, 2H), 7.22 – 7.19 (m, 2H), 7.12 (t, J = 8 Hz, 2H), 6.87 (s, 1H), 1.92 (s,
2
o
1
m.p. 291-293 C; H NMR (400 MHz, DMSO-d
6
1
3
3
1
(
H); C NMR (100 MHz, DMSO-d
6
) δ 168.7, 162.0 (JC,F= 244 Hz), 158.0, 146.5, 143.7, 137.1,
19
33.4, 132.2 (JC,F= 8 Hz), 123.0, 129.6, 127.3, 117.9, 116.4, 115.1 (JC,F= 21 Hz), 23.2; F NMR
376 MHz, DMSO-d
+
6
) δ -112.7;HRMS (ESI) calculated for C19
H16FN
2
O S (M+H) 403.0758,
5
found 403.0743.
N-((4-(6-(t-Butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-
yl)phenyl)sulfonyl)acetamide
To a solution of 4-(6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-
yl)benzenesulfonamide (150 mg, 0.30 mmol) in pyridine (1 mL) under nitrogen, acetic anhydride
(
0.1 mL, 1.06 mmol) followed by DMAP (11 mg, 0.09 mmol) were added. It was stirred for 18
hours at room temperature. After the reaction was completed, it was diluted with EtOAc and
washed with 2N HCl followed by brine. The organic layer was dried over Na SO and
concentrated under reduced pressure and the resulting residue was purified by flash
2
4
chromatography on silica gel eluting with 0 to 50% EtOAc/Hexane. This afforded N-((4-(6-(t-
butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-
o
1
yl)phenyl)sulfonyl)acetamide as a white solid (116 mg, 71%); m.p. 162-164 C; H NMR (400
MHz, CDCl ) δ 8.81 (br s, 1H), 7.95 (d, J = 8 Hz, 2H), 7.39 (s, 1H), 7.35 (d, J = 8 Hz, 2H), 7.27
7.24 (m, 2H), 6.92 (t, J = 9 Hz, 2H), 5.34 (s, 2H), 3.94 – 3.92 (m, 2H), 3.62 – 3.60 (m, 2H),
3
–
3
1
3
.38 (s, 3H), 2.10 (s, 3H), 1.69 (s, 9H); C NMR (100 MHz, CDCl ) δ 168.0, 162.3 (JC,F= 246
3
Hz), 154.3, 146.3, 145.6, 141.0, 136.6, 135.4 (JC,F= 4 Hz), 131.6 (JC,F= 8 Hz), 128.3, 127.3,
1
9
1
26.4, 122.3, 114.9 (JC,F= 22 Hz), 94.8, 81.0, 71.6, 68.0, 59.0, 28.8, 23.5; F NMR (376 MHz,
+
CDCl
3
)δ -114.2; HRMS (ESI) calculated for C27
H32FN
2
O
7
S (M+H) 547.1909, found 547.1909.
5
-(4-(1H-1,2,3-Triazol-5-yl)phenyl)-6-(4-fluorophenyl)-3-hydroxypyridin-2(1H)-one (17) To a
solution of 3-(4-(1H-1,2,3-triazol-5-yl)phenyl)-6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-
methoxyethoxy)methoxy)pyridine (50 mg, 0.10 mmol) in anhydrous DCM (2 mL) under
nitrogen, TFA (1 mL) was added. It was then stirred for 3 hours at room temperature. After
removal of solvent, 5-(4-(1H-1,2,3-triazol-5-yl)phenyl)-6-(4-fluorophenyl)-3-hydroxypyridin-
o
2
(1H)-one was crystallized as a white solid in EtOH:Et
2
O (1:2) (27 mg, 77%); dec.142-144 C;
1
H NMR (400 MHz, CDCl3+MeOD) δ 7.84 (s, 1H), 7.62 (d, J = 8 Hz, 2H), 7.17 – 7.14 (m, 2H),
1
3
7
1
1
.08 (d, J = 8 Hz, 2H), 7.04 (s, 1H), 6.94 (t, J = 8 Hz, 2H); C NMR (100 MHz, DMSO-d
6
) δ
61.8 (JC,F= 245 Hz), 158.0, 146.3, 138.0, 132.6, 132.2 (JC,F= 8 Hz), 132.0, 130.5, 130.0, 129.9,
19
25.4, 125.3, 118.3, 117.4, 115.0 (JC,F= 21 Hz); F NMR (376 MHz, DMSO-d ) δ -113.3;
6
+
HRMS (ESI) calculated for C19
H14FN
4
O (M+H) 349.1084, found 349.1095.
2
3
-(4-(1H-1,2,3-Triazol-5-yl)phenyl)-6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-
methoxyethoxy)methoxy)pyridine
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ChemMedChem
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2
5
To a solution of 2-(t-butoxy)-5-(4-ethynylphenyl)-6-(4-fluorophenyl)-3-((2-
methoxyethoxy)methoxy)pyridine (120 mg, 0.27 mmol) in a mixture of DMF (0.9 mL) and
methanol (0.1 mL) under nitrogen, TMSN (0.15 mL, 1.08 mmol) followed by CuI (6 mg, 0.03
mmol) were added. The reaction mixture was then stirred overnight at 100 C. After the
reaction was completed, it was diluted with EtOAc and washed with sat. NH Cl followed by
brine. The organic layer was dried over Na SO and concentrated under reduced pressure and
3
o
4
2
4
the resulting residue was purified by flash chromatography on silica gel eluting with 0 to 50%
EtOAc/Hexane. This afforded 3-(4-(1H-1,2,3-triazol-5-yl)phenyl)-6-(t-butoxy)-2-(4-
fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridine as a white solid (39 mg, 30%); m.p. 154-
o
1
1
–
3
1
1
56 C; H NMR (400 MHz, CDCl
3
) δ 12.34 (br s, 1H), 7.73 (s, 1H), 7.51 (d, J = 8 Hz, 2H), 7.14
7.11 (m, 2H), 7.07 (s, 1H), 7.02 (d, J = 8 Hz, 2H), 6.70 (t, J = 9 Hz, 2H), 5.16 (s, 2H), 3.75–
.73 (m, 2H), 3.43–3.40 (m, 2H), 3.19 (s, 3H), 1.49 (s, 9H); C NMR (100 MHz, CDCl
62.1 (JC,F= 245 Hz), 162.7, 153.7, 146.8, 145.3, 140.9, 140.3, 136.1, 136.0, 131.6 (JC,F= 8 Hz),
30.2, 128.4, 128.0, 127.6, 126.0, 114.7 (JC,F= 22 Hz), 94.8, 80.6, 71.6, 68.0, 59.0, 28.9; F
NMR (376 MHz, CDCl
found 493.2246.
1
3
3
) δ
19
+
3
) δ -115.1;HRMS (ESI) calculated for C27
H30FN
4
O (M+H) 493.2245,
4
2
-(t-Butoxy)-5-(4-ethynylphenyl)-6-(4-fluorophenyl)-3-((2-methoxyethoxy)methoxy)pyridine
To a solution of 2-(t-butoxy)-6-(4-fluorophenyl)-3-((2-methoxyethoxy)methoxy)-5-(4-
(trimethylsilyl)ethynyl)phenyl)pyridine (90 mg, 0.17 mmol) in methanol (5 mL) under nitrogen,
CO (47 mg, 0.34 mmol) was added. The reaction mixture was then stirred for 5 hours at
room temperature. After the reaction was completed, it was diluted with EtOAc and washed
with sat. NH Cl followed by brine. The organic layer was dried over Na SO and concentrated
(
K
2
3
4
2
4
under reduced pressure and the resulting residue was purified by flash chromatography on silica
gel eluting with 0 to 10% EtOAc/Hexane. This afforded 2-(t-butoxy)-5-(4-ethynylphenyl)-6-(4-
1
fluorophenyl)-3-((2-methoxyethoxy)methoxy)pyridine as yellow oil (76 mg, 100%); H NMR
(400 MHz, CDCl
3
) δ 7.31 (d, J = 8 Hz, 2H), 7.29 (s, 1H), 7.21 – 7.18 (m, 2H), 7.04 (d, J = 8 Hz,
2
3
1
8
H), 6.82 (t, J = 9 Hz, 2H), 5.23 (s, 2H), 3.84 – 3.82 (m, 2H), 3.51 – 3.49 (m, 2H), 3.29 (s, 3H),
13
.02 (s, 1H), 1.59 (s, 9H); C NMR (100 MHz, CDCl
3
) δ 162.1 (JC,F= 246 Hz), 153.8, 145.3,
40.9, 140.6, 135.9, 132.1, 131.6 (JC,F= 8 Hz), 129.7, 127.7, 120.5, 114.7 (JC,F= 21 Hz), 94.9,
1
9
3.5, 80.6, 77.6, 71.6, 68.0, 59.0, 28.9; F NMR (376 MHz, CDCl ) δ -115.0;HRMS (ESI)
3
+
calculated for C27
H
29FNO (M+H) 450.2075, found 450.2075.
4
2
(
4
-(t-Butoxy)-6-(4-fluorophenyl)-3-((2-methoxyethoxy)methoxy)-5-(4-
(trimethylsilyl)ethynyl)phenyl)pyridine
-(6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-yl)phenyl
trifluoromethanesulfonate (223 mg, 0.39 mmol), (trimethylsilyl) acetylene (0.17 ml, 1.17 mmol),
Pd(PPh Cl (56 mg, 0.08 mmol), CuI (15 mg, 0.08 mmol) and Et N (0.16 ml, 1.17mmol) were
dissolved in DMF (5 mL). The air was evacuated and replaced with N . Then, the reaction
mixture was stirred for 6 hours at 100 C. After the reaction was completed, it was cooled to
room temperature. It was diluted with EtOAc and washed with sat. NH Cl followed by brine.
The organic layer was dried over Na SO and concentrated under reduced pressure and the
3
)
2
2
3
2
o
4
2
4
resulting residue was purified by flash chromatography on silica gel eluting with 0 to 10%
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ChemMedChem
10.1002/cmdc.201900084
2
6
EtOAc/Hexane. This afforded 2-(t-butoxy)-6-(4-fluorophenyl)-3-((2-methoxyethoxy)methoxy)-
1
5
-(4-((trimethylsilyl)ethynyl)phenyl)pyridine as colorless oil (84 mg, 41%); H NMR (400 MHz,
CDCl ) δ 7.385 (d, J = 8 Hz, 2H), 7.383 (s, 1H), 7.30 –7.27 (m, 2H), 7.11 (d, J = 8 Hz, 2H), 6.91
t, J = 9 Hz, 2H), 5.33 (s, 2H), 3.94 – 3.92 (m, 2H), 3.61 – 3.59 (m, 2H), 3.39 (s, 3H), 1.69 (s,
3
(
1
3
9
1
9
H), 0.28 (s, 9H); C NMR (100 MHz, CDCl
3
) δ 162.2 (JC,F= 246 Hz), 153.9, 145.4, 140.9,
40.3, 136.0, 132.0, 131.6 (JC,F= 8 Hz), 129.6, 127.9, 127.8, 121.6, 114.7 (JC,F= 22 Hz), 105.0,
4.9, 80.7, 71.6, 59.0, 28.9, 0.0; F NMR (376 MHz, CDCl ) δ -115.0; HRMS (ESI) calculated
19
3
+
for C30
H37FNO
4
Si (M+H) 522.2470, found 522.2470.
4
-(6-(t-Butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-yl)phenyl
trifluoromethanesulfonate
To solution of 4-(6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-
yl)phenol (100 mg, 0.23 mmol) in anhydrous DCM (10 mL) under nitrogen, N-phenyl-
o
bis(trifluoromethanesulfonamide) (100 mg, 0.28 mmol) was added. It was cooled to 0 C, and
then Et
temperature, and it was stirred overnight. After the reaction was completed, it was diluted with
EtOAc and washed with sat. NH Cl followed by brine. The organic layer was dried over Na SO
3
N (0.06 mL, 0.41 mmol) was added. The reaction mixture was allowed warm to room
4
2
4
and concentrated under reduced pressure and the resulting residue was purified by flash
chromatography on silica gel eluting with 0 to 50% EtOAc/Hexane. This afforded 4-(6-(t-
butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-yl)phenyl
1
trifluoromethanesulfonate as colorless oil (121 mg, 92%); H NMR (400 MHz, CDCl
3
) δ 7.40 (s,
1
H), 7.28 – 7.19 (m, 6H), 6.92 (t, J = 9 Hz, 2H), 5.34 (s, 2H), 3.95 – 3.93 (m, 2H), 3.62 – 3.60
1
3
(m, 2H), 3.38 (s, 3H), 1.70 (s, 9H); C NMR (100 MHz, CDCl
3
) δ 162.2 (JC,F= 246 Hz), 154.1,
1
1
1
48.4, 145.4, 141.0, 140.6, 135.6 (JC,F= 3 Hz), 131.6 (JC,F= 8 Hz), 131.5, 127.5, 126.5, 121.3,
19
14.8 (JC,F= 22 Hz), 94.8, 80.8, 71.6, 68.0, 59.0, 28.8; F NMR (376 MHz, CDCl
3
)δ -72.8, -
+
14.6; HRMS (ESI) calculated for C26
H
28
F
4
NO
7
S (M+H) 574.1518, found 574.1517.
4
3
-(6-(t-Butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-yl)phenol
-Bromo-6-(t-butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridine (200 mg, 0.47
(58 mg, 0.05 mmol) and
(150 mg, 1.42 mmol) were dissolved in a mixture of dioxane (15 mL) and water (5 mL).
The air was evacuated and replaced with N . Then, the reaction mixture was refluxed for 8
hours. After the reaction was completed, it was cooled to room temperature. It was diluted with
mmol), 4-hydroxyphenylboronic acid (100 mg, 0.71 mmol), Pd(PPh
Na CO
)
3 4
2
3
2
EtOAc and washed with 2N HCl followed by brine. The organic layer was dried over Na
and concentrated under reduced pressure and the resulting residue was purified by flash
2
SO
4
chromatography on silica gel eluting with 0 to 30% EtOAc/Hexane. This afforded 4-(6-(t-
butoxy)-2-(4-fluorophenyl)-5-((2-methoxyethoxy)methoxy)pyridin-3-yl)phenol as a white solid
o
1
(
200 mg, 96%); m.p. 102-104 C; H NMR (400 MHz, MeOD) δ 7.38 (s, 1H), 7.33 – 7.29 (m,
2
3
1
1
H), 6.96 (d, J = 9 Hz, 2H), 6.92 (t, J = 9 Hz, 2H), 6.71 (d, J = 9 Hz, 2H), 5.29 (s, 2H), 3.88 –
1
3
.86 (m, 2H), 3.58 – 3.55 (m, 2H), 3.32 (s, 3H), 1.64 (s, 9H); C NMR (100 MHz, MeOD) δ
63.4 (JC,F= 244 Hz), 157.7, 154.5, 146.3, 142.4, 138.0, 132.8 (JC,F= 8 Hz), 132.4, 131.9, 130.5,
1
9
29.1, 116.3, 115.3 (JC,F= 21 Hz), 95.8, 81.4, 72.8, 69.1, 59.1, 29.3; F NMR (376 MHz,
+
MeOD) δ -117.3;HRMS (ESI) calculated for C25
H
29FNO (M+H) 442.2024, found 442.2025.
5
This article is protected by copyright. All rights reserved.

ChemMedChem
10.1002/cmdc.201900084
2
7
4
4
-(2-(4-Fluorobenzyl)-5-hydroxy-6-oxo-1,6-dihydropyridin-3-yl)benzonitrile (18)
-(2-(4-Fluorobenzyl)-5,6-dimethoxypyridin-3-yl)benzonitrile (146 mg, 0.42 mmol) was
o
dissolved in anhydrous DCM (10 mL). The reaction mixture was cooled to 0 C and the 1M in
DCM BBr (4.2 mL, 4.2 mmol) was added. It was then allowed to warm to room temperature
3
and stirred for 18 hours. Then, the solvent was removed under reduced pressure. The resulting
residue was diluted with EtOAc, which was washed with 2N HCl followed by brine. The
organic layer was dried over Na
2
SO followed by concentration under the vacuum. The residue
4
was purified by flash chromatography on silica gel eluting with 0 to 30% EtOAc/Hexane
followed by 0 to 10% MeOH/DCM to provide 4-(2-(4-fluorobenzyl)-5-hydroxy-6-oxo-1,6-
o
1
dihydropyridin-3-yl)benzonitrileas a white solid (63 mg, 53%); m.p. 191-193 C; H NMR (400
MHz, DMSO-d ) δ 11.95 (bs, 1H), 9.26 (bs, 1H), 7.83 (d, J = 8 Hz, 2H), 7.44 (d, J = 8 Hz, 2H),
.06 (t, J = 9 Hz, 2H), 6.96 (dd, J = 8 Hz, J = 6 Hz, 2H), 6.70 (s, 1H), 3.79 (s, 2H); C NMR
100 MHz, DMSO-d ) δ 160.8 (JC,F= 241 Hz), 158.4, 145.7, 143.2, 134.7, 132.7, 132.4, 130.0,
6
1
3
7
(
1
6
1
9
29.6 (JC,F= 8 Hz), 118.7, 117.7, 116.8, 115.1 (JC,F= 21 Hz), 109.7, 34.1; F NMR (376 MHz,
+
DMSO-d
6
) δ -116.7; HRMS (ESI) calculated for C19
H14FN
2
O (M+H) 321.1034, found
2
3
21.1019.
4
4
-(2-(4-Fluorobenzyl)-5,6-dimethoxypyridin-3-yl)benzonitrile
-(2-Bromo-5,6-dimethoxypyridin-3-yl)benzonitrile (300 mg, 0.94 mmol), 0.5 M in THF (4-
fluorophenyl)zinc(II) chloride (4.7 mL, 2.35 mmol), Johnphos (56 mg, 0.19 mmol), Pd(OAc)
60 mg, 0.09 mmol) and K CO (325 mg, 2.35 mmol)were dissolved in dioxane (20 mL). The
air was evacuated and replaced with N . Then, the reaction mixture was refluxed for 8 hours.
After the reaction was completed, it was cooled to room temperature and it was diluted with
EtOAc and washed with sat. NH Cl followed by brine. The organic layer was dried over Na
2
(
2
3
2
4
2
SO
4
and concentrated under reduced pressure and the resulting residue was purified by flash
chromatography on silica gel eluting with 0 to 30% EtOAc/Hexane. This afforded 4-(2-(4-
fluorobenzyl)-5,6-dimethoxypyridin-3-yl)benzonitrile as a white solid (263 mg, 80%); m.p. 112-
o
1
1
14 C; H NMR (400 MHz, CDCl
3
) δ 7.69 (d, J = 8 Hz, 2H), 7.34 (d, J = 8 Hz, 2H), 7.02 (dd, J
=
9 Hz, J = 6 Hz, 2H), 6.89 (t, J = 9 Hz, 2H), 6.87 (s, 1H), 4.03 (s, 3H), 3.88 (s, 2H), 3.86 (s,
1
3
3
H); C NMR (100 MHz, CDCl
3
) δ 161.4 (JC,F= 243 Hz), 153.5, 144.7, 144.4, 142.3, 135.8
(
5
C
JC,F= 3 Hz), 132.2, 130.2, 130.0 (JC,F= 8 Hz), 128.1, 119.1, 118.6, 114.9 (JC,F= 21 Hz), 111.3,
1
9
5.9, 53.9, 39.4; F NMR (376 MHz, CDCl
3
) δ -117.3; HRMS (ESI) calculated for
+
21
H18FN
2
O
2
(M+H) 349.1437, found 349.1347.
4
-(5-Hydroxy-2-(naphthalen-1-ylmethyl)-6-oxo-1,6-dihydropyridin-3-yl)benzonitrile (19)
4
-(5,6-Dimethoxy-2-(naphthalen-1-ylmethyl)pyridin-3-yl)benzonitrile (116 mg, 0.31 mmol) was
o
dissolved in anhydrous DCM (10 mL). The reaction mixture was cooled to 0 C and the 1M in
DCM BBr (3.05 mL, 3.05 mmol) was added. It was then allowed to warm to room temperature
3
and stirred for 18 hours. Then, the solvent was removed under reduced pressure. The resulting
residue was diluted with EtOAc, which was washed with 2N HCl followed by brine. The
organic layer was dried over Na
2
SO followed by concentration under the vacuum. The residue
4
was purified by flash chromatography on silica gel eluting with 0 to 30% EtOAc/Hexane
This article is protected by copyright. All rights reserved.

ChemMedChem
10.1002/cmdc.201900084
2
8
followed by 0 to 10% MeOH/DCM to provide 4-(5-hydroxy-2-(naphthalen-1-ylmethyl)-6-oxo-
o
1
1
(
1
6
1
1
,6-dihydropyridin-3-yl)benzonitrileas a white solid (37 mg, 35%); m.p.133-135 C; H NMR
400 MHz, DMSO-d ) δ 11.89 (bs, 1H), 9.29 (bs, 1H), 7.94 – 7.89 (m, 2H), 7.80 (d, J = 8 Hz,
H), 7.71 (d, J = 8 Hz, 2H), 7.55 – 7.49 (m, 2H), 7.44 (d,J = 8 Hz, 1H), 7.40 (d, J = 8 Hz, 2H),
6
1
3
.98 (d, J = 7 Hz, 1H), 6.81 (s, 1H), 4.23 (s, 2H); C NMR (100 MHz, DMSO-d
6
) δ158.5,
45.9, 143.1, 135.0, 133.2, 132.3, 132.0, 131.0, 129.4, 128.5, 126.9, 126.2, 125.9, 125.6, 124.7,
+
23.2, 118.6, 117.6, 109.6, 32.5; HRMS (ESI) calculated for C23
H
16
N
2
O Na (M+Na) 375.1104,
2
found 375.1107.
4
4
-(5,6-Dimethoxy-2-(naphthalen-1-ylmethyl)pyridin-3-yl)benzonitrile
-(2-Bromo-5,6-dimethoxypyridin-3-yl)benzonitrile (200 mg, 0.63 mmol), 0.25 M in THF
(
naphthalen-1-ylmethyl)zinc(II) chloride (6.27 mL, 1.57 mmol), Johnphos (37 mg, 0.13 mmol),
Pd(OAc) (42 mg, 0.06 mmol) and K CO (217mg, 1.57 mmol) were dissolved in dioxane (20
mL). The air was evacuated and replaced with N . Then, the reaction mixture was refluxed for 2
hours. After the reaction was completed, it was cooled to room temperature and it was diluted
with EtOAc and washed with sat. NH Cl followed by brine. The organic layer was dried over
Na SO and concentrated under reduced pressure and the resulting residue was purified by flash
2
2
3
2
4
2
4
chromatography on silica gel eluting with 0 to 30% EtOAc/Hexane. This afforded 4-(5,6-
dimethoxy-2-(naphthalen-1-ylmethyl)pyridin-3-yl)benzonitrile as a white solid (202 mg, 85%);
o
1
m.p. 173-175 C; H NMR (400 MHz, CDCl
.71 (d, J = 8 Hz, 1H), 7.65 (dd, J = 7 Hz, J = 2 Hz, 2H), 7.49 – 7.43 (m, 2H), 7.40 (dd, J = 7 Hz,
J = 2 Hz, 2H), 7.32 (dd, J = 8 Hz, J = 7 Hz, 1H), 6.98 (dd, J = 7 Hz, J = 1Hz, 1H), 6.94 (s, 1H),
3
) δ 7.80 (d, J = 8 Hz, 1H), 7.84 (d, J = 8 Hz, 1H),
7
1
3
4
1
1
4
.43 (s, 2H), 3.94 (s, 3H), 3.90 (s, 3H); C NMR (100 MHz, CDCl
42.3, 136.4, 133.8, 132.2, 132.0, 130.1, 128.6, 128.5, 126.8, 126.6, 125.7, 125.5, 125.3, 124.2,
19.1, 118.7, 111.2, 55.9, 53.9, 37.6; HRMS (ESI) calculated for C25
03.1417, found 403.1423.
3
) δ 153.4, 144.8, 144.3,
H
20
N
2
O
Na (M+Na)+
2
4
-(5-Hydroxy-2-(naphthalen-2-ylmethyl)-6-oxo-1,6-dihydropyridin-3-yl)benzonitrile (20)
4
-(5,6-Dimethoxy-2-(naphthalen-2-ylmethyl)pyridin-3-yl)benzonitrile (139 mg, 0.37 mmol) was
o
dissolved in anhydrous DCM (10 mL). The reaction mixture was cooled to 0 C and the 1M in
DCM BBr (3.65 mL, 3.65 mmol) was added. It was then allowed to warm to room temperature
3
and stirred for 18 hours. Then, the solvent was removed under reduced pressure. The resulting
residue was diluted with EtOAc, which was washed with 2N HCl followed by brine. The
organic layer was dried over Na
2
SO followed by concentration under the vacuum. The residue
4
was purified by flash chromatography on silica gel eluting with 0 to 30% EtOAc/Hexane
followed by 0 to 10% MeOH/DCM to provide 4-(5-hydroxy-2-(naphthalen-2-ylmethyl)-6-oxo-
o
1
1
,6-dihydropyridin-3-yl)benzonitrileas a white solid (44 mg, 34%); m.p. 167-169 C; H NMR
(
7
400 MHz, DMSO-d ) δ 12.00 (bs, 1H), 9.26 (bs, 1H), 7.86 – 7.78 (m, 5H), 7.48 – 7.44 (m, 4H),
6
1
3
.41 (s, 1H), 7.14 (d, J = 8 Hz, 1H), 6.76 (s, 1H), 3.98 (s, 2H); C NMR (100 MHz, DMSO-d )
6
δ 158.4, 145.8, 143.3, 136.3, 132.9, 132.6, 132.4, 131.6, 129.9, 128.0, 127.4, 126.5, 126.2, 125.9,
1
3
25.6, 118.7, 117.7, 117.1, 109.7, 35.1;HRMS (ESI) calculated for C23
75.1104, found 375.1106.
H N
16 2
O
Na (M+Na)+
2
This article is protected by copyright. All rights reserved.

ChemMedChem
10.1002/cmdc.201900084
2
9
4
4
-(5,6-Dimethoxy-2-(naphthalen-2-ylmethyl)pyridin-3-yl)benzonitrile
-(2-Bromo-5,6-dimethoxypyridin-3-yl)benzonitrile (200 mg, 0.63 mmol), 0.5 M in THF
(
naphthalen-2-ylmethyl)zinc(II) bromide (3.14 mL, 1.57 mmol), Johnphos (37 mg, 0.13 mmol),
Pd(OAc) (42 mg, 0.06 mmol) and K CO (217mg, 1.57 mmol) were dissolved in dioxane (20
mL). The air was evacuated and replaced with N . Then, the reaction mixture was refluxed for 8
hours. After the reaction was completed, it was cooled to room temperature and it was diluted
with EtOAc and washed with sat. NH Cl followed by brine. The organic layer was dried over
Na SO and concentrated under reduced pressure and the resulting residue was purified by flash
2
2
3
2
4
2
4
chromatography on silica gel eluting with 0 to 30% EtOAc/Hexane. This afforded 4-(5,6-
dimethoxy-2-(naphthalen-2-ylmethyl)pyridin-3-yl)benzonitrile as a white solid (207 mg, 87%);
o
1
m.p. 151-153 C; H NMR (400 MHz, CDCl
3
) δ 7.81 (dd, J = 7 Hz, J = 2 Hz, 1H), 7.75 – 7.68
(
m, 4H), 7.48 – 7.44 (m, 3H), 7.39 (dd, J = 7 Hz, J = 2 Hz, 2H), 7.33 (dd, J = 8 Hz, J = 2 Hz,
1
3
1
1
1
H), 6.93 (s, 1H), 4.12 (s, 2H), 4.09 (s, 3H), 3.90 (s, 3H); C NMR (100 MHz, CDCl
44.8, 144.5, 142.3, 138.0, 133.5, 132.1, 132.0, 130.3, 128.3, 127.8, 127.6, 127.5, 127.4, 126.8,
26.0, 125.4, 119.1, 118.7, 111.2, 55.9, 53.9, 40.5; HRMS (ESI) calculated for C25
3
) δ 153.5,
H
21
N
2
O
2
+
(M+H) 381.1598, found 381.1596.
5
4
-(4-(1H-Tetrazol-5-yl)phenyl)-6-(4-fluorobenzyl)-3-hydroxypyridin-2(1H)-one (21)
-(2-(4-Fluorobenzyl)-5-hydroxy-6-oxo-1,6-dihydropyridin-3-yl)benzonitrile (70 mg, 0.22
(57 mg, 0.88 mmol) were dissolved in anhydrous DMF (1 mL). The reaction
mixture was treated with catalytic amount of acetic acid. It was sealed and then it was heated at
mmol) and NaN
3
o
1
30 C for overnight. The reaction was cooled to room temperature and gave brownish
suspension. After the completion of the reaction, the solvent was re- moved under vacuum.
Addition of 2N HCl and stirring produced a solid, which was filtered to give the pure product (33
o
1
mg, 41%); dec. 154-156 C; H NMR (400 MHz, DMSO-d
6
) δ 11.91 (bs, 1H), 9.26 (bs, 1H),
8
1
1
.03 (d, J = 8 Hz, 2H), 7.49 (d, J = 8 Hz, 2H), 7.07 (t, J = 9 Hz, 2H), 7.01 – 6.97 (m 2H), 6.74 (s,
1
3
H), 3.83 (s, 2H); C NMR (100 MHz, DMSO-d
34.9, 132.4, 130.0, 129.6 (JC,F = 8 Hz), 127.1, 118.0, 117.3, 115.1 (JC,F = 21 Hz), 34.1; F NMR
6
) δ 160.8 (JC,F = 241 Hz), 158.4, 145.6, 141.1,
19
+
(376 MHz, DMSO-d
6
) δ -116.7; HRMS (ESI) calculated for C19
H15FN
5
2
O (M+H) 364.1204,
found 364.1182.
5
4
0
-(4-(1H-Tetrazol-5-yl)phenyl)-3-hydroxy-6-(naphthalen-1-ylmethyl)pyridin-2(1H)-one (22)
-(5-Hydroxy-2-(naphthalen-1-ylmethyl)-6-oxo-1,6-dihydropyridin-3-yl)benzonitrile (25 mg,
.07mmol) and NaN (18 mg, 0.28 mmol) were dissolved in anhydrous DMF (1 mL). The
3
reaction mixture was treated with catalytic amount of acetic acid. It was sealed and then it was
o
heated at 130 C for overnight. The reaction was cooled to room temperature and gave brownish
suspension. After the completion of the reaction, the solvent was re- moved under vacuum.
Addition of 2N HCl and stirring produced a solid, which was filtered to give the pure product (25
o
1
mg, 89%); dec. 156-158 C; H NMR (400 MHz, DMSO-d
6
) δ 11.87 (bs, 1H), 9.27 (bs, 1H),
7
=
.96 – 7.90 (m, 4H), 7.82 (d, J = 8 Hz, 1H), 7.56 – 7.50 (m, 2H), 7.48 – 7.44 (m, 3H), 7.04 (d, J
1
3
8 Hz, 1H), 6.87 (s, 1H), 4.29 (s, 2H); C NMR (100 MHz, DMSO-d ) δ 158.5, 145.8, 141.0,
6
1
1
35.1, 133.2, 131.7, 131.0, 129.4, 128.5, 127.0, 126.9, 126.2, 125.9, 125.6, 124.8, 123.2, 118.0,
+
17.9, 32.6; HRMS (ESI) calculated for C23
H18FN
5
2
O (M+H) 396.1455, found 396.1455.
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