3-Hydroxypyridin-2-thione as Novel Zinc Binding Group for Selective Histone Deacetylase Inhibition

Article abstract of DOI:10.1021/jm301769u

Small molecules bearing hydroxamic acid as the zinc binding group (ZBG) have been the most effective histone deacetylase inhibitors (HDACi) to date. However, concerns about the pharmacokinetic liabilities of the hydroxamic acid moiety have stimulated rese

Full text of DOI:10.1021/jm301769u

Article
pubs.acs.org/jmc
3‑Hydroxypyridin-2-thione as Novel Zinc Binding Group for Selective
Histone Deacetylase Inhibition
Vishal Patil,†,∥ Quaovi H. Sodji,†,∥ James R. Kornacki,§ Milan Mrksich,*,§ and Adegboyega K. Oyelere*,†,‡
‡
†School of Chemistry and Biochemistry, Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of
Technology, Atlanta, Georgia 30332-0400, United States
§Department of Chemistry and Howard Hughes Medical Institute, Northwestern University, 2145 Sheridan Road, Evanston, Illinois
60208-3113, United States
S
* Supporting Information
ABSTRACT: Small molecules bearing hydroxamic acid as the zinc binding group (ZBG) have
been the most effective histone deacetylase inhibitors (HDACi) to date. However, concerns
about the pharmacokinetic liabilities of the hydroxamic acid moiety have stimulated research
efforts aimed at finding alternative nonhydroxamate ZBGs. We have identified 3-hydroxypyridin-
2-thione (3-HPT) as a novel ZBG that is compatible with HDAC inhibition. 3-HPT inhibits
HDAC 6 and HDAC 8 with an IC50 of 681 and 3675 nM, respectively. Remarkably, 3-HPT gives
no inhibition of HDAC 1. Subsequent optimization led to several novel 3HPT-based HDACi that
are selective for HDAC 6 and HDAC 8. Furthermore, a subset of these inhibitors induces
apoptosis in various cancer cell lines.
including a short half-life and poor bioavailability.15−17 The
INTRODUCTION
■
hydroxamate also chelates other biologically relevant metals,
Eukaryotic DNA is wrapped around nucleosomes comprised of
histone proteins that are subjected to various post-translational
modifications including acetylation, phosphorylation, sumoyla-
tion, and methylation. These post-translational modifications
including Fe2+ and Cu2+, with affinities that can exceed that of
Zn2+ ion.18,19 Extensive reports have aimed to improve the
HDAC inhibition profile by manipulating the surface
recognition cap group and linker region while retaining the
function to regulate transcription.1,2 Histone acetylation/
hydroxamic acid as ZBG. Indeed, these efforts have resulted in
deactylation, which have been the most studied covalent
highly potent and, in some cases, isoform-selective com-
modifications, are mediated by the histone acetyl transferases
pounds.20,21
(HATs) and the histone deacetylases (HDACs), respectively.3,4
Several efforts have replaced the hydroxamic acid with
We now know that a significant fraction of cellular proteins are
alternative chemical moieties.22 For example, MS-275 is a class
also substrates for HDAC and HAT enzymes, extending their
I selective HDACi having a benzamide ZBG.23 It has been
role beyond that of transcriptional regulation.5 Presumably due
suggested that the benzamide ZBG exploits the difference in
to their involvement in repressing transcription, various HDAC
the region adjacent to the active site to achieve its isoform
isoforms are overexpressed in different cancers and as such are
selectivity.24 Further, subtle differences in the active sites of
valid targets for cancer treatment.6 In fact, two histone
various HDAC isoforms have been exploited to design
deacetylase inhibitors (HDACi), suberoylanilide hydroxamic
acid (SAHA) and cyclic peptide FK228, are approved for the
compounds having other ZBGs, including thiols, α-ketoesters,
electrophilic ketones, mercaptoamides, and phosphonates.11,25
treatment of cutaneous T-cell lymphoma (CTCL).4 Other
However, most of these analogues had reduced potency.
pathological conditions where targeting HDAC constitute a
Nonhydroxamate chemotypes that chelate Zn2+ ion have
plausible therapeutic option include inflammatory diseases,
been well studied in the context of inhibitors of the matrix
metalloproteins (MMPs) (Figure 2). This work has revealed
parasitic infections, hemoglobinopathies, and neurodegener-
ative diseases.7−10
that bidentate heterocyclic ZBGs are stronger metal chelators
The classic pharmacophoric model of HDACi consists of a
than are the monodentate analogues.26,27 Furthermore, the
zinc binding group (ZBG) that chelates the active site Zn2+ ion,
bidentate heterocyclic ZBGs are resistant to hydrolysis and are
a linker, and a surface recognition cap group that interacts with
effective at inhibiting the proteinase activities of various MMP
the amino acid residues present at the surface of the HDAC
isoforms.27 We therefore borrowed the bidentate heterocyclic
ZBGs to evaluate a new class of HDACi that may be devoid of
(Figure 1).11
Chelation of the Zn2+ ion has proven crucial for HDAC
inhibition.12 The hydroxamic acid has been the preferred ZBG
due to its strong Zn2+ ion chelation.13,14 Yet the hydroxamic
acid could present metabolic and pharmacokinetic challenges,
Received: November 30, 2012
Published: April 2, 2013
© 2013 American Chemical Society
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Figure 1. (a) HDACi pharmacophoric model. (b) Representative examples of HDACi (note color code highlights the three pharmacophores).
Figure 2. Representative examples of bidentate heterocyclic and monodentate nonhydroxamate ZBGs.26,28
many of the liabilities of the hydroxamate moiety. We herein
report that 3-hydroxypyridin-2-thione (3-HPT) is a bidentate
heterocyclic ZBG that is compatible with HDAC inhibition. 3-
HPT inhibits the deacetylase activities of HDAC 6 and HDAC
8 with IC50 of 680 and 3700 nM, respectively. Remarkably, 3-
HPT is inactive against HDAC 1. Subsequent optimization led
to several novel 3-HPT-based HDACi that are selective for
HDAC 6 and HDAC 8. Furthermore, a subset of these
inhibitors induces apoptosis in various cancer cell lines.
RESULTS AND DISCUSSION
■
Initial Molecular Docking Studies. We first performed
molecular docking analyses on selected bidentate heterocyclic
ZBG fragments against three HDAC isoforms: HDAC 1,
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HDAC 6, and HDAC 8. Our choice of bidendate ZBG
fragments is informed by their reported Zn2+ ion chelation
affinity and the ease with which subsequent modification could
be introduced to enhance potency.26,27 The bidendate ZBG
fragments that met these criteria, 3-hydroxypyridin-2-one, 3-
hydroxypyridin-2-thione, 3-hydroxypyridin-4-thione, and 1-
hydroxypyridin-2-thione, were selected for initial studies
(Figure 3). We performed docking analyses against the crystal
participates in potentially stabilizing H-bonding interactions at
the base of the enzyme active sites. Although 1-hydroxypyridin-
2-thione shows Zn2+ ion chelation at HDAC active sites
(Supporting Information, Figures S1−S3), this ZBG is similar
to hydroxamic acid and it is synthetically less tractable relative
to 3-HP and 3-HPT. On the basis of these observations, we
directed our efforts on the 3-HP and 3-HPT fragments. To test
the validity of our in silico predictions, we investigated the
effects of 3-HPT 2 and 3-HP 3 on the deacetylase activities of
HDAC 1, HDAC 6, and HDAC 8. 3-HPT 2 was synthesized
from the commercially available 3-hydroxypyridin-2-one as
previously reported.32
In Vitro HDAC Inhibition Activity of 3-HP and 3-HPT
Fragments. We used SAMDI mass spectrometry as previously
described to assay inhibitor potency against the HDAC
isoforms 1, 6, and 8.30,33,34 3-HPT 2 inhibited HDAC6 with
an IC50 of 680 nM and inhibited HDAC8 with an IC50 of 3.7
μM. This compound had no activity against HDAC 1 (Table
1). The analogue 3-HP 3 was inactive against each of the three
HDAC isoforms. The disparity in the HDAC inhibition activity
of 3-HP and 3-HPT could be due to the thiophilicity of zinc
which favors 3-HPT.35
The inactivity of 3-HPT against HDAC 1 may not be
surprising giving the ambivalence of its interaction with the
HDAC 1 (homology model) and HDLP active sites
(Supporting Information, Figure S1). This data suggests that
the docked structure of 3-HPT on HDLP may closely mimic its
binding with HDAC 1. Alternatively, it is plausible that the
narrowness of HDAC 1 tunnel, relative to those of HDAC 6
and HDAC 8, could constitute a challenge toward proper
accommodation of 3-HPT at HDAC 1 active site. HDAC 1
activity or lack thereof could then be influenced by conforma-
tional changes which are not captured by docking analysis such
as AutoDock.
Structure−Activity Relationship (SAR) Studies. We
next performed docking analyses of the N-1 methyl, benzyl,
and biphenyl derivatives of 3-HP and 3-HPT and found that
the compounds were predicted by AutoDock to adopt docking
poses similar to 3-HP and 3-HPT (see Supporting Information
Figures S4 and S5 for docking results on N-1 methyl
derivative). We then synthesized representative examples of
these compounds, N-1 methyl (5a), benzyl (5b and 7b), and
biphenyl (5c and 7c) derivatives (Scheme 1), and tested their
HDAC inhibition activities against HDACs 1, 6, and 8. As
observed with the 3-HP/3-HPT pair, carbonyl-compounds 5a,
5b, and 5c failed to inhibit HDAC activity (data not shown).
The thione-compounds 7b and 7c inhibited HDAC 6 with
midnanomolar IC50s and less potent activity against HDAC 8
(Table 2). Similar to our observation with 3-HPT, neither 7b
nor 7c possess any measurable activity against HDAC 1 at
maximum tested concentration of 10 μM. The anti-HDAC 6
and 8 activities of 7b and 7c mirrored those of 3-HPT,
Figure 3. Docked bidendate ZBG fragments: (a) 1-hydroxypyridin-2-
thione (1a), (b) 3-hydroxypyridin-4-thione (1b), (c) 3-hydroxypyr-
idin-2-thione (3-HPT) (2), (d) 3-hydroxypyridin-2-one (3-HP) (3).
structures of HDAC 8 (PDB code: 1VKG),29 histone
deacetylase-like protein (HDLP), a HDAC 1 homologue,12
and the homology models of HDAC 1 and HDAC 6 built
respectively from human HDAC 2 (PDB code: 3MAX) and
HDAC 8 (PDB code: 3FOR)21 using a validated molecular
docking program (AutoDock 4.2) as described previously.30,31
Preliminary docking analyses revealed that 3-hydroxypyridin-
2-one (3-HP), 3-hydroxypyridin-2-thione (3-HPT), 3-hydrox-
ypyridin-4-thione, and 1-hydroxypyridin-2-thione chelate the
Zn2+ ion at active site of HDLP, HDACs 1, 6 and 8, suggesting
that these bidentate heterocycles could provide the critical ZBG
in the HDACi pharmacophoric model. A closer inspection of
the docked poses in HDACs 1, 6, and 8 revealed that the N-1
position of 3-hydroxypyridin-4-thione is oriented toward the
base of the active site pocket as opposed to the N-1 positions of
3-HP and 3-HPT, which are oriented toward the surface of the
channel that the linker region of prototypical HDACi occupies
to present the surface recognition cap group to the enzyme
outer rim. Conversely, the docked poses of 3-HP and 3-HPT at
HDLP active site that retained zinc chelation are those in which
their N1-positions are oriented toward the base of the active
site pocket in similar manner to the N-1 position of 3-
hydroxypyridin-4-thione (Supporting Information, Figures S1−
S3). In HDLP, the N-1 position of 3-HPT engages in hydrogen
bonding with GLY129, which stabilizes its orientation, however,
in the HDAC 1 homology model, the outward orientation of
the 3-HPT is probably influenced by the prospect of hydrogen
bonding of its N-1 with TYR303 phenol group and GLY149
backbone (Supporting Information, Figure S1C).
The docked poses adopted by 3-HP and 3-HPT, particularly
on HDACs 6 and 8, should enable facile introduction of linkers
and surface recognition cap groups through the N-1 position in
order to further enhance HDAC inhibition potency. Such
modifications, however, could compromise inhibition activity of
the 3-hydroxypyridin-4-thione fragment as its N-1 position
a
Table 1. HDAC Inhibition Activities of 3-HP and 3-HPT
a
†
Activities determined by SAMDI analysis. No significant Inhibition (below 20% Inhibition) at maximum tested concentration of 10 μM.
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a
Scheme 1. Synthesis of the 3-HP and 3HPT-Based ZBG HDACi
a
(a) R-CH2Br, K2CO3, DMF, 100 °C; (b) Lawesson’s reagent, toluene, reflux; (c) BBr3, CH2Cl2; (d) MeI, KOH, MeOH, rt.
however, 7b is somewhat more active against both HDAC
isoforms. That the biphenyl moiety of 7c did not increase
affinity of this compound for the HDAC may reflect a lack of
interactions of this hydrophobic group with the hydrogen-
bonding surface of the protein channel.
We reasoned that the diaryl moiety of 7c could be tuned to
introduce interactions with the enzyme active site channel
residues. We substituted the proximal phenyl group with a
1,2,3-triazole ring to give analgoues 15a and 17a. In silico
interrogation against HDACs 6 and 8 again revealed that 15a
and 17a adopted poses whereby the active site Zn2+ ion
chelation is maintained in both isoforms. Interestingly, the
triazole ring of either compound is positioned close to the
HDAC 8 Tyr306 OH-group for possible H-bonding. The
analogous interaction is missing in HDAC 6 (Figure 4; note
that only the docked poses of the 3-HPT diaryl 17a are shown
for clarity).
We next synthesized the diaryl compounds 15a and 17a and
their analogues (discussed later) using the route shown in
Scheme 3 and tested their HDAC inhibition activities against
HDACs 1, 6, and 8. Consistent with the observations described
above, the 3-HP compound 15a is inactive against the HDAC
isoforms tested. Surprisingly, 3-HPT diaryl 17a is only
marginally inhibitory to HDAC 6 at a concentration of 10
μM, quite in contrast to the effect of the analogous compound
7c. We also found that 17a is about 2−3-fold more active
against HDAC 8 relative to 7c (Table 2). This result is
consistent with our in silico observation which suggested that
the triazole ring could be beneficial to HDAC 8 inhibition
(Figure 4).
Encouraged by these results, we focused our SAR studies on
7c and 17a as leads, introducing substituents at the distal
phenyl group (relative to the ZBG). We prepared a series of
aromatic and heteroaromatic derivatives to investigate the effect
of the substitution pattern and the nature of substituents on
inhibition activity. Because we used a Suzuki cross coupling36 to
join the 3-HP phenyl bromide 8 with a phenyl boronic acid, we
could readily prepare several analogous biphenyl compounds
(9a−i). Subsequent deprotection of the O-methoxy group with
boron tribromide gave 3-HP biphenyl compounds 11a−i.
Alternatively, the reaction of 9a−i with Lawesson’s reagent
resulted in O-methoxy protected 3-HPT biphenyl compounds
10a−i, which upon treatment with boron tribromide furnished
the desired 3-HPT biphenyl compounds 12a−i (Scheme 2).
Consistent with the pattern seen with the previous analogues,
all 3-HP biphenyl compounds 11a−i lacked HDAC inhibition
activity against HDACs 1, 6, and 8 (data not shown). Similarly,
all the 3-HPT biphenyl compounds 12a−i are inactive against
HDAC 1 while the majority possess substituent dependent
inhibitory activities against HDACs 6 and 8 with varying
degrees of selectivity for either isoform (Table 2). Compound
12a, an analogue of 7c with a cyano-substituent at the para-
position, inhibits HDAC 6 at a level nearly identical to that of
7c while it is about 2-fold better HDAC 8 inhibitor relative to
7c. A shift of the cyano-substitution to the meta-position in
compound 12b resulted in the abrogation of HDAC 6
inhibition while a slight enhancement of HDAC 8 inhibition
was observed. Ortho placement of the cyano-substituent in
compound 12c restored HDAC 6 inhibition with higher
potency relative to compounds 7b and 7c, while HDAC 8
inhibitory activity remained largely unperturbed. Interestingly,
methyl substituted compounds 12d−f are strongly inhibitory to
HDAC 6 irrespective of the position of substitution. In fact,
compound 12f is the strongest HDAC 6 inhibitor in this series
of 3-HPT biphenyl compounds with IC50 of 306 nM (Table 2).
Conversely, the ability of compounds 12d−f to inhibit HDAC
8 is very sensitive to the placement of the methyl substituent.
The para-methyl derivative 12d is more active, with IC50 of 800
nM, than the corresponding meta-methyl and ortho-methyl
analogues, 12e and 12f, respectively. Placement of the electron
donating N,N-dimethylamino group at the para-position in
compound 12g, analogous to the substitution pattern on the
surface recognition group of simple HDACi Trichostatin A
(TSA), resulted in loss of HDAC 6 inhibition while HDAC 8
inhibition activity at micromolar IC50 is about 2-fold enhanced
relative to the lead compound 7c. The 4-pyridyl substitution in
compound 12i partially restored HDAC 6 inhibition lost in 12g
without any added benefit to HDAC 8 inhibition. Interestingly,
the combination of pyridine and N,N-dimethylamine sub-
stitutions as seen in compound 12h resulted in the loss of
HDAC 8 inhibition and a low micromolar HDAC 6 activity, a
near mirror image of the HDAC inhibition preference of 12g.
Finally, we found that the incorporation of N,N-dimethylamino
group at the para-position of triazole containing 3-HPT 17a, to
afford compound 17b, did not improve HDAC 8 selectivity.
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a
Table 2. In Vitro HDAC Inhibition of Phenyl and Biphenyl HDACi
a
†
∗No significant Inhibition (below 20% Inhibition). % inhibition of the compounds at 10 μM are given if the IC50 was above 10 μM.
Instead, it conferred HDAC 6 inhibition activity to 17b. A
similar substitution on the biphenyl congeners improved
HDAC 8 inhibition but resulted in the loss of HDAC 6
inhibition (Table 2, comparing 12g and 17b). This observation
suggests a possible divergence in the SARs of the triazole and
biphenyl 3-HPT compounds. We describe the furtherance of
our SAR studies on the triazole 3-HPT compounds in the next
manuscript.
We then performed further docking analyses on representa-
tive compounds against HDAC 6 to gain a better under-
standing of the molecular basis of their stronger binding
interaction with this HDAC isoform. We docked compounds
12a−f, which showed a clear dependence of substitution
pattern on HDAC inhibition activities (Table 2). The docked
poses adopted by these compounds gave insights into the
preference for ortho-substituents in the analogues (Figure 5).
The biphenyl moieties of the ortho-substituted compounds 12c
and 12f adopted a nearly indistinguishable orientation in which
the cyano and methyl groups, respectively, are neatly nestled
within a hydrophobic pocket at the enzyme outer rim where
they could engage in potentially stabilizing hydrophobic
interactions with amino acid residues including Tyr782 and
Phe620. In contrast, the cyano and methyl groups of
compounds 12a, 12b, 12d, and 12e are not oriented toward
the same hydrophobic pocket. Instead, they are solvent
exposed, thus missing the potentially stabilizing hydrophobic
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Figure 4. Docked structures of 3-HPT diaryl 17a at the active site of (a) HDAC 6 and (b) HDAC 8. Note that the placement of the triazole ring of
17a could facilitate H-bonding interaction with the OH-group of HDAC 8 Tyr306.
a
Scheme 2. Synthesis of the Biphenyl 3-HP and 3-HPT-Based HDACi
a
(a) 4-Bromobenzylbromide, K2CO3, THF, reflux; (b) R-B(OH)2, Pd(PPh3)4, K2CO3, toluene:ethanol:H2O, 80 °C; (c) Lawesson’s reagent,
toluene, reflux; (d) BBr3, CH2Cl2.
a
Scheme 3. Synthesis of the Triazole 3-HP and 3-HPT-Based HDACi
a
(a) Propargyl bromide, K2CO3, THF, reflux; (b) azido intermediates (phenyl azide, 4-azido-N,N-dimethylaniline), CuI, DIPEA, THF; (c) BBr3,
CH2Cl2; (d) Lawessons’ reagent, toluene, reflux.
interactions enjoyed by their ortho-substituted congeners. This
observation might explain the enhanced potency of 12c and 12f
against HDAC 6 compared to 12a, 12b, 12d, and 12e (Table
2).
To further probe the structural basis for the hindrance of the
proper accommodation of these 3HPT-based compounds at
HDAC 1 active site, we docked compound 12d, analogue with
potent HDAC 6 and 8 inhibition activities but lacking the
potentially obstructive ortho/meta substitution, against HDAC
1 homology model and HDLP. We observed that 12d was
incapable of entering HDAC 1 pocket to chelate the zinc at the
active site, instead it was bound to the residues at the surface of
the binding pocket. While 12d bound to mutiple spots on
HDLP, none of its conformation was able to present the 3HPT
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Figure 5. Docked poses adopted by 3-HPT compounds 12a−f at HDAC 6 active site. (a) Overlay of low energy conformations of 12a (purple), 12b
(green), and 12c (white): (i) surface view, (ii) ball and stick model showing crucial residues at enzyme outer rim hydrophobic pocket. (b) Overlay of
low energy conformations of 12d (orange), 12e (pink), and 12f (yellow): (i) surface view, (ii) ball and stick model showing crucial residues at
enzyme outer rim hydrophobic pocket.
ZBG for chelation to the active site zinc ion (Supporting
Information Figure S6). This in silico observation may further
explain the lack of activity of this class of compounds against
HDAC 1.
Table 3. Cell Viability Assay: IC50 of Selected Compounds
against Various Cancer Cell Lines
cellular IC50(μM)
Jurkat
In Vitro Cell Growth Inhibition. We tested several of the
compounds in proliferation assays of cancer cell lines DU-145
(androgen independent prostate cancer), LNCaP (androgen
dependent prostate cancer), and the T-cell leukemia cell line
Jurkat. The compounds included a selective HDAC8 inhibitor
(12g), compounds that inhibited both HDAC6 and 8 (12c and
12f) and a triazole-based inhibitor selective for HDAC8 (17a).
Although 3-HPT 2 is active against HDAC6 and to some
extend HDAC8, it is inactive against the three cancer cell lines
tested (Table 3). The discrepancy between the HDAC
inhibition profile and the antiproliferative activity of 3-HPT
may be due to solubility problems that limit its diffusion across
the cell membrane.37 Against DU-145, a prostate cancer line
known to be responsive to HDACi such as SAHA or TSA, only
compd
DU-145
LNCaP
NI
Jurkat
NI
J.gamma1
a
b
3-HPT
(2)
NI
NT
12g
>20
>20
16.23 1.11
14.65 0.84
7.75 0.73
13.11 1.51
2.31 0.74
10.62 0.67
8.95 0.69
3.19 0.30
4.68 0.34
1.49 0.10
NI
NT
NI
NI
NI
12c
12f
13.59 2.91
>20
17a
SAHA
2.49 0.2
a
b
NI = no inhibition. NT = not tested.
12f exhibited a weak activity; all other compounds were inactive
at the highest tested concentration of 20 μM (Table 3). SAHA,
which was used as a positive control, had IC50 value comparable
to that reported in the literature.38
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The compounds were more active on the LNCaP cell line
(Table 3). Compound 12f is the most potent of the biphenyls,
followed by 12c and 12g. Interestingly, the cell growth
inhibition activity of the triazolyl compound 17a is comparable
to that of 12c although 17a is a weak HDAC 6 inhibitor (only
41% inhibition at 10 μM, Table 2). With the exception of 17a,
the observed trend of the cell growth inhibition activity
mirrored that of the HDAC 6 inhibition seen in Table 2. This
may be due to the fact that LNCaP cells are sensitive to the
acetylation state of HSP90. Hyperacetylation of HSP90,
induced by the tested 3-HPT derived HDACi, attenuates its
interactions with proteins such as androgen receptors, which
are key to the survival of LNCaP cells.39,40
Because T-cell-derived leukemia cell line Jurkat has been
previously shown to be sensitive to selective HDAC 8
inhibitor,41 we investigated the effects of our compounds on
the viability of Jurkat cells. Overall, all the compounds,
excluding 3-HPT, inhibit Jurkat cell growth with single-digit
micromolar IC50 values (Table 3). Compound 12f, which
inhibited both HDAC 6 and HDAC 8, is the most potent
against the Jurkat cells (IC50 = 3.19 μM) in a similar manner to
its activity against LNCaP cells. The HDAC 8 selective
compounds 12g and 17a are cytotoxic to the Jurkat cells with
17a, the more potent HDAC 8 inhibitor of the two, being twice
as potent. The enhanced cytotoxicity of 17a relative to 12g
could suggest a causal relationship between HDAC 8 inhibition
and the apoptotic effect against Jurkat cells.
(Supporting Information Figure S7 and Table S1). For these
two compounds, poor solubility may explain the lack of cellular
activity.42,43 However, the solubilities of the other compounds
tested are beyond the suggested threshold that limits cellular
activity.42,43 Hence, the reduced efficacy of many of these
compounds may be attributable to factors other than solubility
issues.
Intracellular Target Validation. Of the compounds tested
for anticancer activity, 12f is approximately 10-fold selective
toward HDAC 6 compared to HDAC 8. To probe the
contribution of HDAC 6 inhibition to the cytotoxic activity of
12f, we determined the level of tubulin acetylation, a common
marker for intracellular HDAC 6 inhibition, in LNCaP cells
through Western blot. We observed that 12f led to an increase
in tubulin acetylation in LNCaP cells at IC50 concentration and
at 20 μM (Figure 6), while SAHA, used as a positive control,
Figure 6. Western blot analysis of tubulin acetylation (HDAC6
inhibition) in LNCaP cell line. Lanes: 1, SAHA (20 μM); 2, SAHA
IC50 (2.31 μM); 3, control; 4, 12f (20 μM); 5, 12f IC50 (7.75 μM).
The apoptotic pathway, which is mediated by the activity of
phospholipase C γ1 (PLCγ1) in Jurkat cells, is believed to be
initiated by an HDAC 8 specific enzyme.41 Balasubramanian
and co-workers reported that an HDAC 8 specific inhibitor,
PCI-34051, lost its ability to induce apoptosis in Jurkat
J.gamma1, a mutant Jurkat cell line which has no detectable
PLCγ1 activity.41 To further delineate the contribution of
HDAC 8 to apoptosis induction, we probed the effect of
compounds 12f, 12g, 17a, and SAHA on the viability of Jurkat
J.gamma1 cells. As anticipated for HDAC 8 selective inhibitors,
compounds 12g and 17a are devoid of antiproliferative activity
against Jurkat J.gamma1 (Table 3). Quite unexpectedly, 12f
(which inhibited HDACs 6 and 8) and SAHA (a much broader
HDACi) are noncytotoxic to this mutant Jurkat cell line. The
inactivity of 12g and 17a against Jurkat J.gamma1 confirmed
HDAC 8 contribution to their bioactivity. In the Jurkat cell line,
Ca2+ released through PLCγ1 triggers cascade of events
resulting in mitochondrial cytochrome c release and caspase-
dependent apoptosis. The defect in intracellular Ca2+
mobilization in the Jurkat J.gamma1 mutant may also explain
the inactivity of 12f and SAHA, as this prevents the increase in
cytochrome c release observed in the wild-type Jurkat.41
Alternatively, the observed dependence of the cytotoxicity
activity of 12f and SAHA on PLCγ1 activity may be due to the
attenuation of caspase-dependent apoptosis which is crucial for
the cytotoxicity of HDACi.
showed concentration dependent tubulin hyperacetylation as
observed before.44 This data provides evidence for the
involvement of intracellular HDAC 6 inhibition as part of the
mechanisms of antiproliferative activity of 12f.
CONCLUSION
■
We report that 3-hydroxypyridin-2-thione (3-HPT) is a novel
ZBG that is compatible with HDAC inhibition. All of the 3-
HPT-derived compounds reported herein are inactive against
HDAC 1, but many possessed varying degrees of activity in
inhibiting HDAC 6 and HDAC 8. Additionally, a subset of
these compounds is cytotoxic to various cancer cell lines. The
pattern of changes to key intracellular markers induced by
representative members of these compounds confirmed the
contribution of HDACs 6 and 8 to their bioactivity. To the best
of our knowledge, this study described the first use of 3-HPT as
ZBG for HDAC inhibition. Because of their anticipated
immunity to many of the metabolic and pharmacokinetic
liabilities that has beleaguered the hydroxamate ZBG, these 3-
HPT-derived HDACi may display improved in vivo activity.
EXPERIMENTAL SECTION
■
Materials and Methods. Bromoalkanoic acid, benzyl bromide, 4-
bromobenzylbromide, 4-(bromomethyl)-1,1′-biphenyl, 3-methoxy-
2(1H)-pyridone, propargyl bromide, phenylacetylene, and representa-
tive boronic acids were purchased from either Sigma−Aldrich or Alfa−
Aesar. Anhydrous solvents and other reagents were purchased and
On the basis of the foregoing, there is a discrepancy between
HDAC inhibition and the whole cell activities of some of the
tested compounds. This is to be expected as it is not unusual to
observe such a lack of correlation between the two experiments.
It is, however, possible that compound solubility could play a
significant role in cell penetration which may perturb the whole
cell activities. Therefore, we estimated the solubility of all
compounds tested in cell growth inhibition assay to probe for
the effect of solubility on antiproliferative activity. Among these
compounds, 3HPT and 12g had solubility less than 65 μg/mL
used without further purification. Analtech silica gel plates (60 F254
)
were used for analytical TLC, and Analtech preparative TLC plates
(UV 254, 2000 μm) were used for purification. UV light was used to
examine the spots. Silica gel (200−400 mesh) was used in column
chromatography. NMR spectra were recorded on a Varian-Gemini 400
1
magnetic resonance spectrometer. H NMR spectra were recorded in
parts per million (ppm) relative to the peak of CDCl3, (7.24 ppm),
CD3OD (3.31 ppm), or DMSO-d6 (2.49 ppm). 13C spectra were
recorded relative to the central peak of the CDCl3 triplet (77.0 ppm),
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CD3OD (49.0 ppm), or the DMSO-d6 septet (39.7 ppm) and were
recorded with complete heterodecoupling. Multiplicities are described
using the abbreviation: s, singlet; d, doublet; t, triplet; q, quartet; m,
multiplet; app, apparent. High-resolution mass spectra were recorded
at the Georgia Institute of Technology mass spectrometry facility in
Atlanta. All final 3HPT-based compounds were established to be >95%
pure using HPLC. These HPLC analyses were done on a Beckman
Coulter instrument with a Phenomenex RP C-18 column (250 mm ×
4.6 mm), using water (solvent A) and acetonitrile (solvent B) gradient,
starting from 40% to 80% of B over 20 min. The flow rate was 1 mL/
min, and detection was at 379 nm. Phenyl azide and 4-azido-N,N-
dimethylaniline were synthesized as previously reported.45,46 DU-145,
LNCaP, and Jurkat J.gamma1 were obtained from ATCC (Manassas,
VA, USA), and Jurkat E6-1 cell line was kindly donated by Dr. John
McDonald and grown on recommended medium supplemented with
10% fetal bovine serum (Global Cell Solutions, Charlottesville, VA,
USA) at 37 °C in an incubator with 5% CO2. Mouse antiacetylated α-
tubulin antibody was obtained from Invitrogen (Life Technologies,
Grand Island, NY, USA), rabbit antiactin, and rabbit antitubulin α
antibodies were purchased from Sigma-Aldrich (St. Louis, MO, USA).
Secondary antibodies, goat antirabbit conjugated to IRDye680, and
goat antimouse conjugated to IRDye800 were purchased from LI-
COR Biosciences (Lincoln, NE, USA). The CellTiter 96 AQueous
One Solution Cell Proliferation assay (MTS) kit was purchased from
Promega (Madison, WI, USA).
Histone Deacetylase Inhibition. The HDAC activity in presence of
various compounds was assessed using the SAMDI mass spectrometry.
As a label-free technique, SAMDI is compatible with a broad range of
native peptide substrates without requiring potentially disruptive
fluorophores. To obtain IC50 values, we incubated isoform-optimized
substrates (50 μM) with enzyme (250 nM) and inhibitor (at
concentrations ranging from 10 nM to 1.0 mM) in 96-well microtiter
plates (60 min, 37 °C). Solution-phase deacetylation reactions were
quenched with trichostatin A (TSA) and transferred to SAMDI plates
to immobilize the substrate components. SAMDI plates were
composed of an array of self-assembled monolayers (SAMs)
presenting maleimide in standard 384-well format for high-throughput
handling capability. Following immobilization, plates were washed to
remove buffer constituents, enzyme, inhibitor, and any unbound
substrate and analyzed by MALDI mass spectrometry using automated
protocols.34 Deacetylation yields in each triplicate sample were
determined from the integrated peak intensities of the molecular
ions for the substrate and the deacetylated product ion by taking the
ratio of the former over the sum of both. Yields were plotted with
respect to inhibitor concentration and fitted to obtain IC50 values for
each isoform−inhibitor pair.
Cell Viability Assay. DU-145 cells were maintained in EMEM
supplemented with 10% FBS while all other cell lines were maintained
in RPMI 1640 supplemented with 10% FBS. DU-145 and LNCaP cells
were incubated on a 96-wells plate for 24 h prior to the drug
treatment, while Jurkat and Jurkat J.gamma1 cells were incubated in
media containing the various compounds for 72 h. Cell viability was
measured using the MTS assay according to manufacturer protocol.
The DMSO concentration in the cell media during the cell viability
experiment was maintained at 0.1%.
Western Blot Analysis for Tubulin Acetylation. LNCaP cells were
plated for 24 h and treated with various concentrations of compounds
for 4 h. The cells were washed with PBS buffer and resuspended in
CelLyticM buffer containing a cocktail of protease inhibitor (Sigma-
Aldrich, St. Louis, MO, USA). Following quantification through a
Bradford protein assay, an equal amount of protein was loaded onto an
SDS-page gel (Bio-Rad, Hercules, CA, USA) and resolved by
electrophoresis at a constant voltage of 100 V for 2 h. The gel was
transfer onto a nitrocellulose membrane and probed for acetylated
tubulin, tubulin, and actin as loading control.
1-Methyl-3-methoxypyridin-2-one (4a). To a stirring mixture of 3-
methoxypyridin-2-one (0.20 g, 1.6 mmol) and KOH (0.18 g, 3.2
mmol) in methanol was added MeI (0.68 g, 4.8 mmol) dropwise in a
round-bottom flask. Stirring continued overnight at room temperature,
during which a quantitative consumption of starting materials was
observed. The reaction mixture was diluted with water (35 mL) and
CHCl3 (40 mL), and the two layers were separated. The organic layer
was washed with water (35 mL) and brine (30 mL) and dried over
Na2SO4. Solvent was evaporated off in vacuo to yield 4a (0.20 g, 89%)
1
as a colorless oil. H NMR (400 MHz, CDCl3) δ 6.66 (m, 1H), 6.35
(d, J = 7.4 Hz, 1H), 5.83 (t, J = 7.1 Hz, 1H), 3.52 (s, 3H), 3.28 (s,
3H). 13C NMR (100 MHz, CDCl3) δ 158.0, 149. 6, 128.8, 111.9,
104.3, 55.44, 37.1.
1-Benzyl-3-methoxypyridin-2-one (4b). To a stirring mixture of 3-
methoxypyridin-2-one (0.20 g, 1.6 mmol) and K2CO3 (0.66 g, 4.8
mmol) in DMF (8 mL) was added benzyl bromide (0.33 g, 1.92
mmol) dropwise in a condenser equipped round-bottom flask.
Reaction mixture was heated at 100 °C overnight. The reaction
mixture was cooled down, diluted with water (40 mL) and CHCl3 (50
mL), and the two layers were separated. The organic layer was washed
with water (3 × 40 mL) and brine (30 mL) and dried over Na2SO4.
Solvent was evaporated off in vacuo to yield 4b (0.26 g, 75%) as a
1
colorless oil without any further purification needed. H NMR (400
MHz, CDCl3) δ 7.26 (m, 5H), 6.85 (dd, J = 6.9, 1.7 Hz, 1H), 6.54 (dd,
J = 7.5, 1.6 Hz, 1H), 6.03 (m, 1H), 5.13 (s, 2H), 3.76 (s, 3H). 13C
NMR (100 MHz, CDCl3) δ 157.9, 150.1, 136.3, 128. 6, 128.0, 127.7,
111.8, 104.8, 104.8, 55.6, 51.6.
1-(1,1′-Biphenylmethyl)-3-methoxypyridin-2-one (4c). The reac-
tion of 3-methoxypyridin-2-one (0.20 g, 1.6 mmol), K2CO3 (0.66 g,
4.8 mmol), and (4-bromomethyl)-1,1′-biphenyl (0.47 g, 1.92 mmol)
in DMF (8 mL) according to method described for the synthesis of 4b
followed by column chromatography in CH2Cl2 with acetone (0−15%
gradient) followed by CH2Cl2 with MeOH (0−5% gradient) afforded
4c (0.35 g, 76%) as a colorless oil. 1H NMR (400 MHz, CDCl3) δ 7.48
(dd, J = 25.9, 20.6 Hz, 4H), 7.32 (m, 5H), 6.88 (m, 1H), 6.54 (d, J =
7.2 Hz, 1H), 6.04 (t, J = 7.1 Hz, 1H), 5.16 (s, 2H), 3.76 (s, 3H). 13C
NMR (100 MHz, CDCl3) δ 157.9, 150.0, 140.5, 140.2, 135.3, 128.5,
128.4, 127.7, 127.2, 127.1, 126.7, 111.8, 104.8, 55. 6, 51.4.
1-Methyl-3-hydroxypyridin-2-one (5a). To a solution of 4a (0.10
g, 0.68 mmol) in dry CH2Cl2 (8 mL) was slowly added 1 M BBr3
(0.82 mL) at −30 °C under inert atmosphere. The reaction mixture
was stirred for 48 h at room temperature. The mixture was again
cooled to −30 °C, and MeOH (5 mL) was slowly added to the
mixture. After evaporation of solvent, the residue was adjusted to pH 7
with 1 M NaOH and then extracted with CHCl3 (3 × 30 mL). The
combined organic layer was dried over Na2SO4, and solvent was
evaporated in vacuo. The residue was purified by prep-TLC, eluting
with CH2Cl2:acetone:MeOH (10:1:0.2), to give 5a (61 mg, 72%) as
1
an off-white solid. H NMR (400 MHz, CDCl3) δ 7.92 (s, 1H), 6.78
(dd, J = 11.1, 7.1 Hz, 2H), 6.10 (t, J = 7.0 Hz, 1H), 3.57 (s, 3H). 13C
NMR (100 MHz, CDCl3) δ 158.8, 146. 7, 127.6, 114.4, 106.7, 37.3.
HRMS (EI) calcd for C6H7NO2 [M]+ 125.0477, found 125.0477.
1-Benzyl-3-hydroxypyridin-2-one (5b). The reaction of 4b (0.15 g,
0.55 mmol) with 1 M BBr3 (0.66 mL) in dry CH2Cl2 (5 mL) within
48 h as described for 5a afforded 5b (0.13 g, 90%) as a slightly
brownish solid. 1H NMR (400 MHz, CDCl3) δ 7.31 (m, 5H), 6.83 (m,
3H), 6.14 (t, J = 7.1 Hz, 1H), 5.19 (s, 2H). 13C NMR (100 MHz,
CDCl3) δ 158.6, 146. 8, 135.8, 128.7, 128.0, 126.5, 113.9, 107.0, 52.2.
HRMS (EI) calcd for C12H11NO2 [M]+ 201.0792, found 201.0790.
1-(1,1′-Biphenylmethyl)-3-hydroxypyridin-2-one (5c). The reac-
tion of 4c (0.13 g, 0.43 mmol) with 1 M BBr3 (0.51 mL) in dry
CH2Cl2 (7 mL) within 48 h as described for 5a afforded 5c (0.10 g,
1
82%) as a slightly brownish solid. H NMR (400 MHz, DMSO-d6) δ
9.06 (s, 1H), 7.61 (d, J = 7.5 Hz, 4H), 7.36 (m, 6H), 6.70 (d, J = 6.5
Hz, 1H), 6.12 (t, J = 6.9 Hz, 1H), 5.16 (s, 2H). 13C NMR (100 MHz,
DMSO-d6) δ 147.0, 139.8, 139.5, 136.6, 128.9, 128.4, 128.2, 127.5,
126.9, 126.7, 114.8, 105.6, 51.1. HRMS (EI) calcd for C18H15NO2
[M]+ 277.1101, found 277.1103.
Statistical Analysis. The values reported as mean
standard
deviation from at least two independent triplicate experiments. A
student’s t test was performed in Excel, and results with p value less
than 5% were considered statistically different.
1-Benzyl-3-methoxypyridin-2-thione (6b). A suspension of 4b
(0.06 g, 0.28 mmol) and Lawesson’s reagent (0.07 g, 0.17 mmol) in
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toluene (10 mL) was heated at reflux overnight. The reaction mixture
was cooled to room temperature, and solvent was evaporated in vacuo.
The crude solid was purified on prep-TLC, eluting with
CH2Cl2:acetone:MeOH (5:1:0.2), to give 6b (53 mg, 82%) as a
yellow solid. 1H NMR (400 MHz, CDCl3) δ 7.30 (m, 6H), 6.65 (d, J =
7.7 Hz, 1H), 6.54 (t, J = 7.0 Hz, 1H), 5.89 (s, 2H), 3.88 (s, 3H). 13C
NMR (100 MHz, CDCl3) δ 173.2, 159.0, 135.2, 131.7, 128.7, 128.0,
128.0, 111.6, 109.6, 58.8, 56.6. HRMS (EI) calcd for C13H13NOS [M]+
231.0718, found 231.0716.
128.6, 128.4, 128.0, 127.6, 127.5, 118.9, 112.1, 110.9, 105.2, 56.2, 51.8.
HRMS (EI) calcd for C20H6N2O2 [M]+ 316.1212, found 316.1210.
1-(3-Cyano-(1,1′-biphenylmethyl))-3-methoxyoxypyridin-2-one
(9b). The reaction of 8 (0.25 g, 0.85 mmol), (3-cyanophenyl)boronic
acid (0.14g, 0.93 mmol), 2 M aq K2CO3 (0.23 g, 1.69 mmol), and
Pd(PPh3)4 (2.5 mol %) according to method described for the
synthesis of 9a within 18 h afforded 9b (175 mg, 66%) as a white solid.
1H NMR (400 MHz, CDCl3) δ 7.70 (m, 2H), 7.48 (m, 6H), 6.92 (dd,
J = 6.9, 1.6 Hz, 1H), 6.57 (dd, J = 7.4, 1.4 Hz, 1H), 6.08 (t, J = 7.2 Hz,
1H), 5.16 (s, 2H), 3.76 (s, 3H). 13C NMR (100 MHz, CDCl3) δ
158.1, 150.2, 141.7, 138.3, 136.8, 131.4, 130.8, 130. 5, 129.7, 128.9,
128.0, 127.4, 118.8, 112.8, 112.1, 105.3, 55.8, 51.7. HRMS (EI) calcd
for C20H16N2O2 [M]+ 316.1212, found 332.1216.
1-(2-Cyano-(1,1′-biphenylmethyl))-3-methoxyoxypyridin-2-one
(9c). The reaction of 8 (0.15 g, 0.50 mmol), (2-cyanophenyl)boronic
acid (0.09 g, 0.60 mmol), 2 M aq K2CO3 (0.14 g, 1.69 mmol), and
Pd(PPh3)4 (2.5 mol %) according to method described for the
synthesis of 9a within 18 h afforded 9c (118 mg, 75%) of white solid.
1H NMR (400 MHz, CDCl3) δ 7.72 (m, 1H), 7.60 (m, 1H), 7.45 (m,
1-(1,1′-Biphenylmethyl)-3-methoxypyridin-2-thione (6c). The
reaction of 4c (0.13 g, 0.44 mmol) and Lawesson’s reagent (0.11 g,
0.27 mmol) in toluene according to method described for the
synthesis of 6b afforded 6c (122 mg, 88%) as a yellow solid. 1H NMR
(400 MHz, CDCl3) δ 7.52 (m, 1H), 7.35 (m, 2H), 6.66 (dd, J = 7.8,
1.3 Hz, 1H), 6.55 (dd, J = 7.8, 6.6 Hz, 1H), 5.93 (s, 1H), 3.89 (s, 1H).
13C NMR (100 MHz, CDCl3) δ 173.1, 159.0, 140.8, 140.2, 134.1,
131.7, 128.6, 128.4, 127.4, 127.3, 126.8, 111.6, 109. 7, 104.8, 58.5, 56.6.
HRMS (EI) calcd for C19H17NOS [M]+ 307.1031, found 307.1029.
1-Benzyl-3-hydroxypyridin-2-thione (7b). The reaction of 6b (0.05
g, 0.21 mmol) with 1 M BBr3 (0.66 mL) in dry CH2Cl2 (5 mL) within
48 h as described for 5a afforded 7b (34 mg, 72%) as an olive-green
solid. Retention time 21.27 min (solvent gradient: 40−80% solvent B
2H), 6.94 (dd, J = 6.9, 1.7 Hz, 1H), 6.60 (dd, J = 7.4, 1.6 Hz, 1H), 6.10
(t, J = 7.2 Hz, 1H), 5.21 (s, 1H), 3.80 (s, 1H). 13C NMR (100 MHz,
CDCl3) δ 158.0, 150.2, 144.7, 137. 6, 136.9, 133.6, 132. 8, 129.9,
129.0, 128.3, 127.9, 127.6, 118.5, 112.0, 110.9, 105.1, 55.7, 51.6.
HRMS (EI) calcd for C20H16N2O2 [M]+ 316.1212, found 316.1201.
1-(4-Methyl-(1,1′-biphenylmethyl))-3-methoxyoxypyridin-2-one
(9d). The reaction of 8 (0.25g, 0.85 mmol), p-tolylboronic acid (0.14g,
1.02 mmol), 2 M aq K2CO3 (0.23g, 1.69 mmol), and Pd(PPh3)4 (2.5
mol %) according to method described for the synthesis of 9a within
1
in 20 min then constant 80% B for 5 min). H NMR (400 MHz,
CD3OD) δ 7.34 (m, 3H), 6.84 (m, 1H), 5.83 (d, J = 49.5 Hz, 1H). 13
C
NMR (100 MHz, CDCl3) δ 164.7, 134.2, 129.0, 128.5, 128.1, 127.8,
126.7, 118.8, 118.3, 62.2. HRMS (EI) calcd for C12H11NOS [M]+
217.0561, found 217.0762.
1-(1,1′-Biphenylmethyl)-3-hydroxypyridin-2-thione (7c). The re-
action of 6c (0.10 g, 0.32 mmol) with 1 M BBr3 (0.48 mL) in dry
CH2Cl2 (5 mL) within 48 h as described for 5a afforded 7c (74 mg,
90%) as an olive-green solid. Retention time 15.37 min (solvent
gradient: 40−80% solvent B in 20 min then constant 80% B for 5 min)
1H NMR (400 MHz, CD3OD) δ 7.39 (m, 9H), 6.88 (m, 3H), 5.86 (s,
2H). 13C NMR (100 MHz, CDCl3) δ 169.9, 155.2 141.3, 140.2, 133.5,
130.9, 128.7, 128.5, 127.7, 127. 5, 126.9, 113.7, 111.9, 59.8. HRMS
(EI) calcd for C18H15NOS [M]+ 293.0874, found 293.0873.
1
18 h afforded 9d (259 mg, quantitative) as a white solid. H NMR
(400 MHz, CDCl3) δ 7.49 (d, J = 8.1 Hz, 2H), 7.42 (d, J = 8.1 Hz,
2H), 7.33 (d, J = 8.1 Hz, 2H), 7.19 (d, J = 8.0 Hz, 2H), 6.88 (dd, J =
6.9, 1.6 Hz, 1H), 6.54 (dd, J = 7.4, 1.4 Hz, 1H), 6.03 (t, J = 7.2 Hz,
1H), 5.15 (s, 2H), 3.76 (s, 3H), 2.34 (s, 3H). 13C NMR (100 MHz,
CDCl3) δ 157.8, 149.9, 140.4, 137.3, 136.9, 134.9, 129.2, 128.4, 127.7,
126.9, 126.5, 111.8, 104. 8, 55.5, 51.3, 20.8. HRMS (EI) calcd for
C20H19NO2 [M]+ 305.1416, found 305.1422.
1-(4-Bromobenzyl)-3-methoxypyridin-2(1H)-one (8). To a stirring
reaction mixture of 3-methoxypyridin-2-one (2.00 g, 16 mmol) and
K2CO3 (4.42 g, 32 mmol) in THF was added 4-bromobenzyl bromide
(5.20 g, 20.8 mmol) slowly. The reaction mixture was the heated at
reflux overnight, cooled down, and then partitioned between CH2Cl2
(120 mL) and water (60 mL). The organic layer was separated,
washed with water (2 × 60 mL) and brine (1 × 40 mL), and dried on
Na2SO4. Solvent was evaporated in vacuo, and the crude yellowish
solid was triturated with hexanes to give 8 (3.49 g, 74%) as a white
1-(3-Methyl-(1,1′-biphenylmethyl))-3-methoxyoxypyridin-2-one
(9e). The reaction of 8 (0.20 g, 0.68 mmol), m-tolylboronic acid (0.11
g, 0.82 mmol), 2 M aq K2CO3 (0.19 g, 1.36 mmol), and Pd(PPh3)4
(2.5 mol %) according to method described for the synthesis of 9a
1
within 18 h afforded 9e (259 mg, quantitative) as a white solid. H
NMR (400 MHz, CDCl3) δ 7.49 (m, 1H), 7.29 (m, 2H), 7.11 (d, J =
7.2 Hz, 1H), 6.88 (dd, J = 6.9, 1.7 Hz, 1H), 6.53 (dd, J = 7.4, 1.6 Hz,
1H), 6.03 (t, J = 7.2 Hz, 1H), 5.15 (s, 1H), 3.75 (s, 1H), 2.35 (s, 1H).
13C NMR (100 MHz, CDCl3) δ 157.8, 149.9, 140.6, 140.2, 138.0,
135.1, 128.4, 128.3, 127.8, 127.7, 127.5, 127.1, 123.8, 111.8, 104.8,
55.5, 51.3, 21.2. HRMS (EI) calcd for C20H19NO2 [M]+ 305.1416,
found 305.1415.
1-(2-Methyl-(1,1′-biphenylmethyl))-3-methoxyoxypyridin-2-one
(9f). The reaction of 8 (0.20 g, 0.68 mmol), O-tolylboronic acid (0.11
g, 0.82 mmol), 2 M aq K2CO3 (0.19 g, 1.36 mmol), and Pd(PPh3)4
(2.5 mol %) according to method described for the synthesis of 9a
within 18 h afforded 9f (243 mg, 98%) as a white solid. 1H NMR (400
MHz, CDCl3) δ 7.31 (d, J = 7.9 Hz, 1H), 7.17 (m, 2H), 6.93 (m, 1H),
6.56 (dd, J = 7.4, 1.6 Hz, 1H), 6.06 (t, J = 7.2 Hz, 1H), 5.18 (s, 1H),
3.76 (s, 1H), 2.20 (s, 1H). 13C NMR (101 MHz, CDCl3) δ 158.1,
150.2, 141.5, 141.3, 135.2, 135.0, 130.3, 129.7, 129.5, 128.1, 127.9,
127.3, 125.8, 112.1, 105.1, 55.8, 51.8, 20. 5. HRMS (EI) calcd for
C20H19NO2 [M]+ 305.1416, found 305.1419.
1
solid without further purification. H NMR (400 MHz, CDCl3) δ
7.45−7.29 (m, 2H), 7.15 (dd, J = 7.4, 1.2 Hz, 2H), 6.84 (dd, J = 6.9,
1.7 Hz, 1H), 6.55 (dd, J = 7.4, 1.5 Hz, 1H), 6.21−5.79 (m, 1H), 5.06
(s, 2H), 3.76 (s, 3H). 13C NMR (100 MHz, CDCl3) δ 158.0, 150.3,
135.5, 131.8, 129.9, 127.7, 121.9, 112.0, 105.2, 55.8, 51.41. HRMS (EI)
calcd for C13H12BrNO2 [M]+ 293.0051, found 293.0051.
Representative Procedure for Suzuki Coupling Reactions for
Synthesis of 9-1-(4-Cyano-(1,1′-biphenylmethyl))-3-methoxyoxy-
pyridin-2-one (9a). Compound 8 (0.26 g, 0.86 mmol), (4-
cyanophenyl)boronic acid (0.14 g, 0.95 mmol), 2 M aq K2CO3
(0.24 g, 1.73 mmol), toluene (8 mL), EtOH (4 mL), and water (4
mL) were added into reaction flask equipped with magnetic stirrer and
water condenser. The resulting suspension was degassed for 10 min by
sparging with argon gas. Pd(PPh3)4 (2.5 mol %) was added, and the
reaction mixture was heated at reflux overnight under argon
atmosphere. After cooling to room temperature, CH2Cl2 was added
(50 mL) and the mixture was extracted with water (40 mL) and brine
(20 mL) and dried on Na2SO4. Solvent was evaporated in vacuo, and
the residue was purified by column chromatography eluting with
CHCl3:acetone:MeOH (first with 5−20% acetone gradient, no MeOH
followed by 1−8% MeOH step gradient) to give 9a (0.42 g, 78%) as
an off-white solid. 1H NMR (CDCl3, 400 MHz) δ 7.60 (m, 4H), 7.40
(m, 4H), 6.90 (dd, J = 6.8, 1.6 Hz, 1H), 6.55 (dd, J = 7.6, 1.6 Hz, 1H),
6.07 (t, J = 7.2 Hz, 1H), 5.16 (s, 2H), 3.75 (s, 3H). 13C NMR (100
MHz, CDCl3) δ 158.1, 150.3, 145.0, 138.6, 137.1, 132. 6, 132.0, 128.9,
1-(4-Dimethylamino-(1,1′-biphenylmethyl))-3-methoxyoxypyri-
din-2-one (9g). The reaction of 8 (0.25g, 0.85 mmol), (4-
(dimethylamino)phenyl)boronic acid (0.17g, 1.02 mmol), 2 M aq
K2CO3 (0.23g, 1.69 mmol), Pd(PPh3)4 (2.5 mol %) according to
method described for the synthesis of 9a within 18 h afforded 9g (230
1
mg, 81%) as a white solid. H NMR (400 MHz, CDCl3) δ 7.46 (m,
4H), 7.29 (m, 2H), 6.86 (dd, J = 7.2, 2.0 Hz, 1H), 7.73 (m, 2H), 6.52
(dd, J = 7.2, 1.6 Hz, 1H), 6.01 (t, J = 7.2 Hz, 1H), 5.13 (s, 2H), 3.76
(s, 3H), 2.93 (s, 6H). 13C NMR (100 MHz, CDCl3) δ 157.9, 149.9,
149.7, 140.6, 133.8, 128.4, 128.0, 127.7, 127.3, 126.2, 112.4, 111.8,
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104.7, 55.5, 51.3, 40.2. HRMS (EI) calcd for C21H22N2O2 [M]+
334.1681, found 334.1684.
1-(3-Methyl-(1,1′-biphenylmethyl))-3-methoxyoxypyridin-2-thi-
one (10e). The reaction of 9e (0.12 g, 0.37 mmol) and Lawesson’s
reagent (0.09 g, 0.23 mmol) in toluene according to method described
for the synthesis of 10a afforded 10e (112 mg, 93%) as a yellow solid.
1H NMR (400 MHz, CDCl3) δ 7.53 (m, 1H), 7.33 (m, 2H), 7.14 (dd,
J = 7.1, 0.6 Hz, 1H), 6.67 (dd, J = 7.8, 1.2 Hz, 1H), 6.56 (m, 1H), 5.94
(s, 1H), 3.91 (s, 1H), 2.39 (s, 1H). 13C NMR (101 MHz, CDCl3) δ
173.2, 159.1, 141.1, 140.3, 138.2, 134.1, 131.7, 128.6, 128.5, 128.1,
127.7, 127.4, 124.0, 111.6, 109.7, 58.6, 56.6, 21.4. HRMS (EI) calcd for
C20H19NOS [M]+ 305.1187, found 321.1188.
1-(2-Methyl-(1,1′-biphenylmethyl))-3-methoxyoxypyridin-2-thi-
one (10f). The reaction of 9f (0.14 g, 0.45 mmol) and Lawesson’s
reagent (0.11 g, 0.27 mmol) in toluene according to method described
for the synthesis of 10a afforded 10f (118 mg, 86%) as a yellow solid.
1H NMR (400 MHz, CDCl3) δ 7.42 (dd, J = 6.6, 1.0 Hz, 1H), 7.22
1-(4-(6-(Dimethylamino)pyridin-3-yl)benzyl))-3-methoxyoxypyri-
din-2-one (9h). The reaction of 8 (0.43g, 1.44 mmol), (6-
(dimethylamino)pyridine-3-yl)boronic acid (0.2 g, 1.20 mmol), 2 M
aq K2CO3 (0.33g, 2.41 mmol), and Pd(PPh3)4 (2.5 mol %) according
to method described for the synthesis of 9a within 18 h afforded 9h
1
(335 mg, 83%) as a white solid. H NMR (400 MHz, CDCl3) δ 8.28
(d, J = 2.3 Hz, 1H), 7.51 (dd, J = 8.8, 2.5 Hz, 1H), 7.33 (d, J = 8.2 Hz,
2H), 7.22 (d, J = 8.2 Hz, 2H), 6.80 (dd, J = 6.9, 1.6 Hz, 1H), 6.44 (m,
2H), 5.94 (t, J = 7.2 Hz, 1H), 5.04 (s, 2H), 3.66 (s, 3H), 2.97 (s, 6H).
13C NMR (100 MHz, CDCl3) δ 158.1, 157.6, 149.7, 145.5, 137.8,
135.1, 134.2, 128.4, 127.5, 125.7, 123.2, 111.6, 105.2, 104.6, 55.4, 51.2,
37.7. HRMS (EI) calcd for C20H21N3O2 [M]+ 335.1634, found
335.1635.
1-(4-(Pyridin-4-yl)benzyl)-3-methoxy-pyridin-2-one (9i). The re-
action of 8 (0.25g, 0.85 mmol), pyrdin-4-ylboronic acid (0.12g, 1.02
mmol), 2 M aq K2CO3 (0.23g, 1.69 mmol), and Pd(PPh3)4 (2.5 mol
%) according to method described for the synthesis of 9a within 18 h
(m, 3H), 6.68 (d, J = 7.3 Hz, 1H), 6.59 (m, 1H), 5.96 (s, 1H), 3.90 (s,
1H), 2.22 (s, 1H). 13C NMR (101 MHz, CDCl3) δ 159.0, 141.5,
140.9, 135.0, 133.6, 131.8, 130.1, 129.5, 129.4, 127.7, 127.2, 125.6,
111.6, 109. 7, 58. 6, 56.6, 20.3. HRMS (EI) calcd for C20H19NOS [M]+
305.1187, found 321.1189.
1
afforded 9i (203 mg, 82%) as a white solid. H NMR (400 MHz,
CDCl3) δ 8.54 (dd, J = 4.5, 1.6 Hz, 2H), 7.48 (m, 2H), 7.36 (m, 4H),
6.87 (dd, J = 6.9, 1.7 Hz, 1H), 6.53 (dd, J = 7.4, 1.6 Hz, 1H), 6.03 (t, J
= 7.2 Hz, 1H), 5.13 (s, 2H), 3.72 (s, 3H). 13C NMR (100 MHz,
CDCl3) δ 157.8, 150.3, 150.0, 149.9, 147.4, 137.3, 137.3, 128.6, 127.7,
127.0, 121.2, 111.9, 105.0, 55.6, 51.4. HRMS (EI) calcd for
C18H16N2O2 [M]+ 292.1212, found 292.1205.
1-(4-Dimethylamino-(1,1′-biphenylmethyl))-3-methoxyoxypyri-
din-2-thione (10g). The reaction of 9g (0.22 g, 0.67 mmol) and
Lawesson’s reagent (0.16 g, 0.40 mmol) in toluene according to
method described for the synthesis of 10a afforded 10g (172 mg, 73%)
1
as a yellow solid. H NMR (400 MHz, CDCl3) δ 7.39 (m, 5H), 7.22
(m, 2H), 6.69 (m, 3H), 6.65 (m, 1H), 5.82 (s, 2H), 3.82 (s, 3H), 2.88
(s, 6H). 13C NMR (100 MHz, CDCl3) δ 172.4, 158.7, 149.9, 140. 9,
132.5, 131.8, 128.4, 128.2, 127.3, 126.3, 112.7, 112.0, 110.2, 58.7, 56.3,
40.2. HRMS (EI) calcd for C21H22N2OS [M]+ 350.1453, found
350.1451.
1-(4-(6-(Dimethylamino)pyridin-3-yl)benzyl))-3-methoxyoxypyri-
din-2-thione (10h). The reaction of 9h (0.14 g, 0.42 mmol) and
Lawesson’s reagent (0.10 g, 0.25 mmol) in toluene according to
method described for the synthesis of 10a afforded 10h (130 mg,
88%) as a yellow solid. 1H NMR (400 MHz, CDCl3) δ 8.32 (d, J = 2.3
Hz, 1H), 7.56 (dd, J = 8.6, 2.1 Hz, 1H), 7.36 (dd, J = 19.8, 7.3 Hz,
3H), 7.26 (d, J = 8.0 Hz, 2H), 6.61 (d, J = 7.8 Hz, 1H), 6.50 (m, 2H),
5.85 (s, 2H), 3.83 (s, 3H), 3.03 (s, 6H). 13C NMR (100 MHz, CDCl3)
δ 172.7, 158.8, 158.3, 145.7, 138.1, 135.3, 133.1, 131.7, 128.5, 126.0,
123.2, 111.6, 109.6, 105.4, 58.4, 56.5, 37.9. HRMS (EI) calcd for
C20H21N3OS [M]+ 351.1405, found 351.1405.
Representative Procedure for Thionation Reaction: Synthesis of
10-1-(4-Cyano-(1,1′-biphenylmethyl))-3-methoxyoxypyridin-2-thi-
one (10a). A suspension of 9a (0.13 g, 0.42 mmol) and Lawesson’s
reagent (0.10 g, 0.25 mmol) in toluene (10 mL) was heated at reflux
overnight. The reaction mixture was cooled to room temperature, and
solvent was evaporated in vacuo. The residue was purified on prep-
TLC, eluting with CHCl3:acetone:EtOH (12:1:0.2) to give 10a (123
1
mg, 88%) as a yellow solid. H NMR (CDCl3, 400 MHz) δ 7.60 (m,
4H), 7.40 (m, 4H), 6.90 (dd, J = 6.8, 1.6 Hz, 1H), 6.55 (dd, J = 7.6, 1.6
Hz, 1H), 6.07 (t, J = 7.2 Hz, 1H), 5.16 (s, 2H), 3.75 (s, 3H). 13C NMR
(100 MHz, CDCl3) δ 158.1, 150.3, 145.0, 138.6, 137.1, 132. 6, 132.0,
128.9, 128.6, 128.4, 128.0, 127.6, 127.5, 118.9, 112.1, 110.9, 105.2,
56.2, 51.8 HRMS (EI) calcd for C20H16N2OS [M]+ 332.0983, found
332.0987.
1-(3-Cyano-(1,1′-biphenylmethyl))-3-methoxypyridin-2-thione
(10b). The reaction of 9b (0.11 g, 0.36 mmol) and Lawesson’s reagent
(0.09 g, 0.22 mmol) in toluene according to method described for the
1-(4-(Pyridin-4-yl)benzyl)-3-methoxypyridin-2-thione (10i). The
reaction of 9i (0.13 g, 0.45 mmol) and Lawesson’s reagent (0.11 g,
0.27 mmol) in toluene according to method described for the
1
synthesis of 10a afforded 10b (113 mg, 95%) as a yellow solid. H
1
NMR (400 MHz, DMSO-d6) δ 7.92 (m, 3H), 7.84 (m, 2H), 7.71 (d, J
= 8.4 Hz, 2H), 7.36 (d, J = 8.8 Hz, 2H), 7.00 (m, 1H), 6.80 (m, 1H),
5.95 (s, 2H), 3.78 (s, 3H). 13C NMR (100 MHz, CDCl3) δ 173.4,
159.3, 144.8, 138.8, 135.8, 132.6, 131.8, 128.7, 127.6, 127.5, 118.8,
111.8, 111.0, 109.7, 58.6, 56.7. HRMS (EI) calcd for C20H16N2OS
[M]+ 332.0983, found 332.0984.
1-(2-Cyano-(1,1′-biphenylmethyl))-3-methoxyoxypyridin-2-thi-
one (10c). The reaction of 9c (0.09 g, 0.28 mmol) and Lawesson’s
reagent (0.07 g, 0.17 mmol) in toluene according to method described
for the synthesis of 10a afforded 10c (72 mg, 77%) of yellow solid. 1H
NMR (400 MHz, CDCl3) δ 7.74 (m, 1H), 7.63 (td, J = 7.7, 1.4 Hz,
1H), 7.45 (m, 2H), 6.71 (dd, J = 7.8, 1.3 Hz, 1H), 6.62 (dd, J = 7.8, 6.6
Hz, 1H), 6.00 (s, 1H), 5.28 (s, 1H), 3.93 (s, 1H). 13C NMR (101
MHz, CDCl3) δ 173.4, 159.2, 144.7, 137.8, 135.8, 133. 7, 132.9, 132.0,
130.0, 129.2, 128.3, 127.7, 118.6, 111.8, 111.0, 109.8, 58.6, 56.7.
HRMS (EI) calcd for C20H16N2OS [M]+ 332.0983, found 332.0981.
1-(4-Methyl-(1,1′-biphenylmethyl))-3-methoxyoxypyridin-2-thi-
one (10d). The reaction of 9d (0.12 g, 0.39 mmol) and Lawesson’s
reagent (0.09 g, 0.23 mmol) in toluene according to method described
for the synthesis of 10a afforded 10d (117 mg, 94%) as a yellow solid.
1H NMR (400 MHz, CDCl3) δ 7.51 (m, 2H), 7.42 (m, 2H), 7.34 (m,
synthesis of 10a afforded 10i (104 mg, 76%) as a yellow solid. H
NMR (400 MHz, CDCl3) δ 8.59 (d, J = 5.9 Hz, 2H), 7.55 (d, J = 8.3
Hz, 2H), 7.39 (m, 5H), 6.67 (dd, J = 7.8, 1.1 Hz, 1H), 6.58 (dd, J =
7.7, 6.7 Hz, 1H), 5.95 (s, 2H), 3.89 (s, 3H). 13C NMR (100 MHz,
CDCl3) δ 173.3, 159.2, 150.1, 147.4, 137. 7, 136.2, 131. 8, 128.6,
127.3, 121.4, 111.7, 109. 7, 58.5, 56.7. HRMS (EI) calcd for
C18H16N2OS [M]+ 308.0983, found 308.0975.
Representative Procedure for Deprotection of O-Methyl Group:
Synthesis of 11-1-(4-Cyano-(1,1′-biphenylmethyl))-3-hydroxyoxy-
pyridin-2-one (11a). To a solution of 9a (0.10 g, 0.32 mmol) in
dry CH2Cl2 (8 mL) was slowly added 1 M BBr3 (0.35 mL) at −30 °C
under argon atmosphere, and the reaction mixture was stirred for 32 h
at room temperature. The mixture was again cooled to −30 °C, and
then MeOH (5 mL) was slowly added to quench BBr3. Solvent was
evaporated off, and the residue was adjusted to pH 7 with aqueous 1
M NaOH and then extracted with CHCl3 (3 × 30 mL). The combined
organic layer was dried over Na2SO4, and solvent was evaporated in
vacuo. The residue was purified by prep-TLC with
CHCl3:acetone:EtOH (10:1:0.2) to give 11a (89 mg, 94%) as a
1
slightly brownish solid. H NMR (400 MHz, DMSO) δ 9.08 (s, 1H),
7.87 (dd, J = 24.8, 7.9 Hz, 4H), 7.71 (d, J = 7.6 Hz, 2H), 7.40 (d, J =
7.7 Hz, 2H), 7.29 (d, J = 6.7 Hz, 1H), 6.70 (d, J = 6.7 Hz, 1H), 6.13 (t,
J = 6.8 Hz, 1H), 5.18 (s, 2H). 13C NMR (100 MHz, CDCl3) δ 147.1,
145.1, 139.2, 136.8, 132.9, 129.0, 128.0, 127. 9, 127.1, 119.1, 114.2,
111.4, 107.6, 52.5, 29.9. HRMS (ESI) calcd for C19H15N2O2 [M + H]+
303.1128, found 303.1124.
3H), 7.21 (dd, J = 8.4, 0.6 Hz, 2H), 6.66 (dd, J = 7.8, 1.2 Hz, 1H), 6.55
(dd, J = 7.8, 6.6 Hz, 1H), 5.92 (s, 2H), 3.89 (s, 3H), 2.36 (s, 3H). 13
C
NMR (100 MHz, CDCl3) δ 173.1, 159.0, 140.7, 137.3, 137.1, 133.8,
131.7, 129.3, 128.4, 127.1, 126.6, 111.6, 109.7, 58.5, 56.6, 20.9. HRMS
(EI) calcd for C20H19NOS [M]+ 321.1187, found 321.1192.
3502
dx.doi.org/10.1021/jm301769u | J. Med. Chem. 2013, 56, 3492−3506

Journal of Medicinal Chemistry
Article
1-(3-Cyano-(1,1′-biphenylmethyl))-3-hydroxyoxypyridin-2-one
(11b). The reaction of 9b (0.05g, 0.15 mmol) with 1 M BBr3 (0.26
mL) in dry CH2Cl2 within 48 h according to the procedure described
for the synthesis of 11a afforded 11b (44 mg, quantitative) as a
126.8, 126.3, 123.6, 114.2, 107.2, 105.9, 52.1, 38.2. HRMS (EI) calcd
for C19H19N3O2 [M]+ 321.1477, found 321.1479.
1-(4-(Pyridin-4-yl)benzyl)-3-hydroxypyridin-2-one (11i). The re-
action of 9i (0.10 g, 0.34 mmol) with 1 M BBr3 (0.51 mL) in dry
CH2Cl2 within 48 h according to the procedure described for the
1
brownish solid. H NMR (400 MHz, DMSO-d6) δ 9.08 (s, 1H), 8.11
1
(s, 1H), 7.98 (d, J = 7.8 Hz, 1H), 7.70 (m, 4H), 7.40 (d, J = 7.7 Hz,
2H), 7.28 (d, J = 6.2 Hz, 1H), 6.70 (d, J = 6.8 Hz, 1H), 6.13 (t, J = 6.7
Hz, 1H), 5.17 (s, 2H). 13C NMR (101 MHz, CDCl3) δ 146. 8, 141.6,
138.6, 136.1, 131.3, 130.8, 130.5, 129.6, 128.7, 127.5, 126.7, 118.7,
113.9, 113.0, 107.3, 52.3. HRMS (EI) calcd for C19H14N2O2 [M + H]+
302.1055, found 302.1055.
synthesis of 11a afforded 11i (79 mg, 83%) as a brownish solid. H
NMR (400 MHz, CDCl3) δ 8.65 (s, 2H), 7.46 (s, 2H), 7.39 (d, J = 7.9
Hz, 2H), 6.83 (dd, J = 22.5, 7.0 Hz, 2H), 6.16 (t, J = 7.0 Hz, 1H), 5.22
(s, 2H). 13C NMR (100 MHz, CDCl3) δ 150.2, 147.6, 146.8, 138.0,
136.9, 128.7, 127.5, 126.6, 121.6, 113.7, 107.1, 52.2. HRMS (FAB)
calcd for C17H15N2O2 [M + H]+ 279.1133, found 279.1147.
1-(2-Cyano-(1,1′-biphenylmethyl))-3-hydroxyoxypyridin-2-one
(11c). The reaction of 9c (0.072g, 0.15 mmol) with 1 M BBr3 (0.34
mL) in dry CH2Cl2 within 48 h according to the procedure described
for the synthesis of 11a afforded 11c (61 mg, 90%) as a brownish
solid. 1H NMR (400 MHz, CDCl3) δ 7.75 (d, J = 7.6 Hz, 1H), 7.63 (t,
J = 7.7 Hz, 1H), 7.53 (d, J = 7.3 Hz, 1H), 7.43 (m, 2H), 7.12 (m, 1H),
6.86 (dd, J = 28.2, 6.6 Hz, 1H), 6.19 (t, J = 6.1 Hz, 1H), 5.25 (s, 1H).
13C NMR (101 MHz, CDCl3) δ 144. 7, 137.9, 136.4, 133.7, 132.9,
1-(4-Cyano-(1,1′-biphenylmethyl))-3-hydroxyoxypyridin-2-thione
(12a). The reaction of 10a (0.10 g, 0.30 mmol) with 1 M BBr3 (0.33
mL) in dry CH2Cl2 (8 mL) within 48 h according to the procedure
described for the synthesis of 11a afforded 12a (84 mg, 88%) as a
green solid. Retention time 16.58 min (solvent gradient: 40−80%
1
solvent B in 20 min then constant 80% B for 5 min). H NMR (400
MHz, DMSO-d6) δ 7.87 (m, 5H), 7.74 (d, J = 8.1 Hz, 2H), 7.37 (d, J =
8.1 Hz, 2H), 7.04 (m, 1H), 6.90 (d, J = 8.1 Hz, 1H), 5.87 (s, 2H). 13C
NMR (100 MHz, CDCl3) δ 164.5, 144.7, 139.2, 134.6, 132.6, 128. 6,
127.7, 127.6, 118.8, 111.2, 61.8, 29.6. HRMS (EI) calcd for
C19H15N2OS [M]+ 318.0827, found 318.0828.
1-(3-Cyano-(1,1′-biphenylmethyl))-3-hydroxyoxypyridin-2-thione
(12b). The reaction of 10b (0.07 g, 0.21 mmol) with 1 M BBr3 (0.32
mL) in dry CH2Cl2 (5 mL) within 48 h according to the procedure
described for the synthesis of 11a afforded 12b (53 mg, 79%) as a
green solid. Retention time 6.93 min (solvent gradient: 70−90%
solvent B in 10 min and constant 90% of B for 15 min). 1H NMR (400
MHz, CD3OD) δ 7.89 (m, 2H), 7.65 (m, 5H), 7.44 (d, J = 8.2 Hz,
2H), 7.02 (d, J = 7.7 Hz, 2H), 6.77 (m, 1H), 5.90 (s, 2H). 13C NMR
(100 MHz, CD3OD) δ 143.0, 140.0, 132.8, 132.2, 131.7, 131.1, 130.0,
130.0, 129. 9, 128.7, 128.6, 119.8, 113.9, 106.4, 54. 8. HRMS (EI)
calcd for C19H14N2O2 [M + H]+ 318.0827, found 318.0827
130.0, 129.2, 128.2, 127.7, 118. 6, 111.1, 107.2, 52.1. HRMS (EI) calcd
for C19H14N2O2 [M + H]+ 302.1055, found 302.1053.
1-(4-Methyl-(1,1′-biphenylmethyl))-3-hydroxyoxypyridin-2-one
(11d). The reaction of 9d (0.06 g, 0.20 mmol) with 1 M BBr3 (0.30
mL) in dry CH2Cl2 (5 mL) within 48 h according to the procedure
described for the synthesis of 11a afforded 11d (57 mg, quantitative)
1
as a brownish solid. H NMR (400 MHz, DMSO-d6) δ 9.07 (s, 1H),
7.57 (m, 2H), 7.50 (d, J = 8.1 Hz, 2H), 7.34 (d, J = 6.8 Hz, 2H), 7.25
(dd, J = 14.8, 7.1 Hz, 3H), 6.69 (d, J = 7.4 Hz, 1H), 6.11 (t, J = 7.1 Hz,
1H), 5.14 (s, 2H), 2.30 (s, 3H). 13C NMR (100 MHz, DMSO-d6) δ
139.8, 137.3, 137.2, 136.7, 129.9, 128.8, 127.0, 126. 9, 51.7, 21.1.
HRMS (EI) calcd for C19H17NO2 [M]+ 291.1259, found 291.1250.
1-(3-Methyl-(1,1′-biphenylmethyl))-3-hydroxyoxypyridin-2-one
(11e). The reaction of 9e (0.064 g, 0.20 mmol) with 1 M BBr3 (0.30
mL) in dry CH2Cl2 (5 mL) within 48 h according to the procedure
described for the synthesis of 11a afforded 11e (60 mg, quantitative)
1-(2-Cyano-(1,1′-biphenylmethyl))-3-hydroxyoxypyridin-2-thione
(12c). The reaction of 10c (0.042 g, 0.21 mmol) with 1 M BBr3 (0.19
mL) in dry CH2Cl2 (5 mL) within 48 h according to the procedure
described for the synthesis of 11a afforded 12c (31 mg, 78%) as a
green solid. Retention time 12.37 min (solvent gradient: 40−80%
1
as a brownish solid. H NMR (400 MHz, CDCl3) δ 7.56 (d, J = 7.5
Hz, 1H), 7.33 (m, 2H), 7.17 (d, J = 7.2 Hz, 1H), 6.85 (dd, J = 22.2, 6.4
Hz, 1H), 6.16 (t, J = 6.5 Hz, 1H), 5.23 (s, 1H), 2.42 (s, 1H). 13C NMR
(101 MHz, CDCl3) δ 146.7, 141.2, 140.4, 138.3, 134.7, 128.63, 128.4,
128.2, 127.8, 127. 6, 126.6, 124.1, 113.7, 107.0, 52.1, 21. 5. HRMS (EI)
calcd for C19H17NO2 [M]+ 291.1259, found 291.1263.
1
solvent B in 20 min then constant 80% B for 5 min). H NMR (400
MHz, CD3OD) δ 7.77 (dd, J = 7.7, 0.9 Hz, 1H), 7.67 (m, 2H), 7.48
(m, 4H), 7.01 (d, J = 13.1 Hz, 1H), 6.70 (m, 1H), 5.90 (s, 1H). 13C
NMR (101 MHz, CD3OD) δ 145.3, 138.9, 134.4, 133.9, 130.8, 129.9,
128.9, 128.6, 119.2, 115.1, 111.4. HRMS (EI) calcd for C19H14N2O2
[M + H]+ 318.0821, found 318.0827
1-(2-Methyl-(1,1′-biphenylmethyl))-3-hydroxyoxypyridin-2-one
(11f). The reaction of 9f (0.077 g, 0.25 mmol) with 1 M BBr3 (0.38
mL) in dry CH2Cl2 (5 mL) within 48 h according to the procedure
described for the synthesis of 11a afforded 11f (65 mg, 90%) as a
1-(4-Methyl-(1,1′-biphenylmethyl))-3-hydroxyoxypyridin-2-thi-
one (12d). The reaction of 10d (0.06 g, 0.20 mmol) with 1 M BBr3
(0.30 mL) in dry CH2Cl2 (5 mL) within 48 h according to the
procedure described for the synthesis of 11a afforded 12d (45 mg,
73%) as a green solid. Retention time 11.53 min (solvent gradient:
1
brownish solid. H NMR (400 MHz, CDCl3) δ 7.28 (m, 3H), 6.87
(dd, J = 31.4, 6.8 Hz, 1H), 6.18 (t, J = 6.9 Hz, 1H), 5.27 (d, J = 16.7
Hz, 1H), 2.26 (s, 1H). 13C NMR (101 MHz, CDCl3) δ 146.7, 141.8,
141.1, 135.2, 134.3, 130.3, 129.7, 127.7, 127.4, 126.7, 125.8, 113.6,
107.0, 52.2, 20.4. HRMS (EI) calcd for C19H17NO2 [M]+ 291.1259,
found 291.1260.
1
70−90% solvent B in 10 min and constant 90% of B for 15 min). H
NMR (400 MHz, CD3OD) δ 7.70 (d, J = 1.1 Hz, 1H), 7.63 (d, J = 6.3
Hz, 1H), 7.55 (d, J = 8.2 Hz, 2H), 7.40 (m, 3H), 7.21 (d, J = 8.1 Hz,
2H), 7.03 (dd, J = 14.9, 7.8 Hz, 2H), 6.75 (t, J = 7.0 Hz, 1H), 5.87 (s,
2H), 2.35 (s, 3H). 13C NMR (100 MHz, CD3OD) δ 141.4, 137.15,
133.66, 131.83, 129.27, 128.43, 127.05, 126.59, 113.79, 112.26, 59.63,
20.32. HRMS (EI) calcd for C19H17NOS [M]+ 307.1031, found
307.1022.
1-(4-Dimethylamino-(1,1′-biphenylmethyl))-3-hydroxyoxypyri-
din-2-one (11g). The reaction of 9g (0.10 g, 0.30 mmol) with 1 M
BBr3 (0.45 mL) in dry CH2Cl2 (8 mL) within 48 h according to the
procedure described for the synthesis of 11a afforded 11g (84 mg,
1
87%) as a brownish solid. H NMR (400 MHz, DMSO-d6) δ 9.06 (s,
1H), 7.52 (d, J = 8.0 Hz, 3H), 7.28 (m, 4H), 6.76 (m, 2H), 6.10 (t, J =
5.8 Hz, 1H), 5.12 (s, 2H), 2.90 (s, 6H). 13C NMR (100 MHz, CDCl3)
δ 158.7, 150.0, 146.6, 141.1, 135.8, 133.3, 128.8, 128.5, 128.2, 128.1,
128.0, 127.6, 126.6, 113.5, 112.6, 106. 9, 52.1, 40.4. HRMS (EI) calcd
for C20H20N2O2 [M]+ 320.1524, found 320.1512.
1-(3-Methyl-(1,1′-biphenylmethyl))-3-hydroxyoxypyridin-2-thi-
one (12e). The reaction of 10e (0.08 g, 0.20 mmol) with 1 M BBr3
(0.36 mL) in dry CH2Cl2 (5 mL) within 48 h according to the
procedure described for the synthesis of 11a afforded 12e (51 mg,
70%) as a green solid. Retention time 10.52 min (solvent gradient:
1-(4-(6-(Dimethylamino)pyridin-3-yl)benzyl))-3-hydroxyoxypyri-
din-2-one (11h). The reaction of 9h (0.10 g, 0.29 mmol) with 1 M
BBr3 (0.45 mL) in dry CH2Cl2 (7 mL) within 48 h according to the
procedure described for the synthesis of 11a afforded 11h (67 mg,
1
70−90% solvent B in 10 min and constant 90% of B for 15 min). H
NMR (400 MHz, CD3OD) δ 7.53 (m, 1H), 7.30 (m, 2H), 7.12 (d, J =
7.2 Hz, 1H), 6.97 (m, 1H), 6.68 (m, 1H), 5.81 (s, 1H), 2.36 (s, 1H).
13C NMR (101 MHz, CD3OD) δ 141.5, 140.2, 138.3, 128.6, 128.5,
1
83%) as a brownish solid. H NMR (400 MHz, CDCl3) δ 8.40 (s,
1H), 7.66 (d, J = 8.0 Hz, 1H), 7.49 (d, J = 7.7 Hz, 2H), 7.33 (d, J = 7.7
Hz, 2H), 6.84 (dd, J = 27.3, 6.8 Hz, 3H), 6.57 (d, J = 8.7 Hz, 1H), 6.15
(t, J = 7.0 Hz, 1H), 5.20 (s, 2H), 3.12 (s, 6H). 13C NMR (100 MHz,
CDCl3) δ 158.5, 146. 7, 145.7, 138.3, 135.8, 133. 9, 132.0, 128.5,
128.2, 127.7, 127.5, 124.0, 21.2. HRMS (EI) calcd for C19H17NOS
[M]+ 307.1031, found 307.1031.
1-(2-Methyl-(1,1′-biphenylmethyl))-3-hydroxyoxypyridin-2-thi-
one (12f). The reaction of 10f (0.08 g, 0.20 mmol) with 1 M BBr3
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(0.36 mL) in dry CH2Cl2 (5 mL) within 48 h according to the
procedure described for the synthesis of 11a afforded 12f (49 mg,
67%) as a green solid. Retention time 17.67 min (solvent gradient:
400 MHz) δ 3.58 (3H, s), 5.11 (2H, s), 5.93 (1H, t, J = 7.6), 6.42 (1H,
d, J = 7.2), 7.07 (1H, d, J = 6.4), 7.16−7.20 (1H, m), 7.26 (2H, t, J =
7.6), 7.49 (2H, d, J = 8.0). 13C NMR (CDCl3, 100 MHz) δ 44.2, 55.2,
104.7, 112.0, 119.7, 121.8, 127.9, 128.1, 129.0, 136.2, 142.8, 149.3,
157.2. HRMS (EI) calcd for C15H14N4O2 [M]+ 282.1117, found
282.1115.
1-(4-Dimethylamino)phenylltriazolylmethyl-3-methoxypyridin-2-
one (14b). The reaction of 4-azido-N,N-dimethylaniline (0.09 g, 0.61
mmol) and 13 (0.10 g, 0.61 mmol) within 4 h as described for the
synthesis of 14a gave compound 14b (0.13 g, 68%) as a white solid.
1H NMR (400 MHz, CDCl3) δ 8.04 (s, 1H), 7.41 (m, 2H), 7.15 (dd, J
= 6.9, 1.7 Hz, 1H), 6.62 (m, 2H), 6.51 (dd, J = 7.5, 1.6 Hz, 1H), 6.03
(m, 1H), 5.19 (s, 2H), 3.70 (s, 3H), 2.89 (s, 6H). 13C NMR (100
MHz, CDCl3) δ 157.5, 150.2, 149.7, 142.6, 128.2, 126.2, 121.9, 121.4,
112.2, 111.8, 104.9, 55.6, 44.5, 40.1. HRMS (EI) calcd for C17H19N5O2
[M]+ 325.1539, found 325.1544.
1-Phenyltriazolylmethyl-3-hydroxypyridin-2-one (15a). The re-
action of 14a (0.21 g, 0.75 mmol) and 1 M BBr3 in CH2Cl2 (1.5
equiv) withing 48 h as described for the synthesis of 11a gave
compound 15a (0.123 g, 61%) as a brown solid. 1H NMR (DMSO-d6,
400 MHz) δ 5.27 (2H, s), 6.13 (1H, t, J = 6.4), 6.67 (1H, d, J = 7.2),
7.30 (1H, d, J = 5.6), 7.45−7.49 (1H, m), 7.57 (2H, t, J = 7.6), 7.87
(2H, d, J = 8.0), 8.73 (1H, s), 9.08 (1H, s). 13C NMR (101 MHz,
CDCl3) δ 136.6, 129.6, 128.9, 122.3, 120.6, 108.0, 29.3. HRMS (EI)
calcd for C14H12N4O2 [M]+ 268.0960, found 268.0967.
1-(4-Dimethylamino)phenylltriazolylmethyl-3-hydroxypyridin-2-
one (15b). The reaction of 14b (0.045 g, 0.14 mmol) and 1 M BBr3 in
CH2Cl2 (0.22 mL, 1.5 equiv) withing 48 h as described for the
synthesis of 11a gave compound 15b (0.033 g, 77%) as a brown solid.
1H NMR (400 MHz, CDCl3) δ 8.08 (s, 1H), 7.48 (dd, J = 19.9, 8.4
Hz, 2H), 7.18 (d, J = 6.7 Hz, 1H), 6.69 (ddd, J = 25.8, 24.8, 7.5 Hz,
4H), 6.16 (t, J = 6.9 Hz, 1H), 5.31 (s, 2H), 2.98 (m, 6H). 13C NMR
(101 MHz, CDCl3) δ 158.4, 150.5, 146.7, 142.5, 127.1, 126.4, 122.1,
121.9, 121.8, 112.1, 107.1, 44.7, 40.3. HRMS (EI) calcd for
C16H17N5O2 [M]+ 311.1382, found 311.1386.
1-Phenyltriazolylmethyl-3-methoxypyridin-2-thione (16a). The
reaction of 14a (0.30 g, 1.04 mmol) and Lawesson’s reagent (0.25
g, 0.62 mmol) in toluene (15 mL) within 12 h as described for the
synthesis of 10a gave compound 16a (0.29 g, 94%) as a yellow solid.
1H NMR (CDCl3, 400 MHz) δ 3.90 (3H, s), 6.04 (2H, s), 6.62−6.68
(2H, m), 7.38−7.42 (1H, m), 7.48 (2H, t, J = 7.2), 7.68 (2H, d, J =
8.0), 7.82 (1H, d, J = 4.8), 8.53 (1H, s). 13C NMR (CDCl3, 100 MHz)
δ 50.9, 56.4, 110.0, 112.0, 120.2, 122.4, 128.5, 129.3, 132.2, 136.4,
141.9, 158.7, 171.5. HRMS (EI) calcd for C15H14N4O2 [M]+ 282.1117,
found 282.1115. HRMS (EI) calcd for C15H14N4OS [M]+ 298.0888,
found 298.0888.
1
40−80% solvent B in 20 min then constant 80% B for 5 min). H
NMR (400 MHz, CD3OD) δ 7.54 (m, 1H), 7.19 (m, 3H), 6.98 (m,
1H), 6.70 (m, 1H), 5.83 (s, 1H), 2.19 (s, 1H). 13C NMR (100 MHz,
CD3OD) δ 142.1, 141.0, 135.1, 130.2, 129.6, 129.5, 127.8, 127.3,
125.7, 20.0. HRMS (EI) calcd for C19H17NOS [M]+ 307.1031, found
307.1034.
1-(4-Dimethylamino-(1,1′-biphenylmethyl))-3-hydroxyoxypyri-
din-2-thione (12g). The reaction of 10g (0.11 g, 0.33 mmol) with 1 M
BBr3 (0.39 mL) in dry CH2Cl2 (5 mL) within 48 h according to the
procedure described for the synthesis of 11a afforded 12g (68 mg,
62%) as a green solid. Retention time 10.42 min (solvent gradient:
1
70−90% solvent B in 10 min and constant 90% of B for 15 min). H
NMR (400 MHz, CDCl3) δ 8.57 (d, J = 8.5 Hz, 1H), 7.53 (d, J = 8.2
Hz, 2H), 7.46 (m, 2H), 7.33 (d, J = 8.0 Hz, 3H), 6.97 (d, J = 6.8 Hz,
1H), 6.77 (d, J = 8.8 Hz, 2H), 6.62 (m, 1H), 5.79 (s, 2H), 2.98 (s,
6H). 13C NMR (100 MHz, CDCl3) δ 169.7, 155.1, 150.1, 141.5, 131.9,
130.8, 129.0, 128.8, 128.0, 127.6, 126.7, 113.6, 112.6, 111.9, 60.1, 40. 5.
HRMS (EI) calcd for C20H20N2OS [M]+ 336.1296, found 336.1295.
1-(4-(6-(Dimethylamino)pyridin-3-yl)benzyl))-3-hydroxyoxypyri-
din-2-thione (12h). The reaction of 10h (0.064 g, 0.18 mmol) with 1
M BBr3 (0.27 mL) in dry CH2Cl2 (5 mL) within 48 h according to the
procedure described for the synthesis of 11a afforded 12h (48 mg,
79%) as a green solid. Retention time 27.43 min (solvent gradient:
1
40−80% solvent B in 20 min then constant 80% B for 15 min). H
NMR (400 MHz, CDCl3) δ 8.30 (s, 1H), 7.70 (d, J = 8.9 Hz, 1H),
7.46 (s, 2H), 7.31 (t, J = 7.6 Hz, 3H), 6.98 (d, J = 7.8 Hz, 1H), 6.67
(m, 2H), 5.75 (s, 2H), 3.11 (s, 8H). 13C NMR (100 MHz, CDCl3) δ
157.0, 143. 5, 142.2, 137.7, 137.0, 132.8, 128.8, 127. 6, 126.4, 123.7,
114.4, 107.0, 38.5, 29.5. HRMS (EI) calcd for C19H19N3OS [M]+
337.1249, found 337.1251.
1-(4-(Pyridin-4-yl)benzyl)-3-hydroxypyridin-2-thione (12i). The
reaction of 10i (0.08 g, 0.25 mmol) with 1 M BBr3 (0.38 mL) in
dry CH2Cl2 (5 mL) within 48 h according to the procedure described
for the synthesis of 11a afforded 12i (65 mg, 88%) as a green solid.
Retention time 19.37 min (solvent gradient: 40−80% solvent B in 20
min then constant 80% B for 10 min). 1H NMR (400 MHz, CDCl3) δ
8.65 (d, J = 5.3 Hz, 2H), 8.55 (s, 1H), 7.62 (d, J = 8.0 Hz, 2H), 7.42
(m, 5H), 6.99 (d, J = 7.5 Hz, 1H), 6.67 (t, J = 7.0 Hz, 1H), 5.85 (s,
2H). 13C NMR (100 MHz, CDCl3) δ 170.1, 155.3, 150.3, 147.4, 138.2,
135.5, 130.9, 128.8, 127.6, 121.5, 113.7, 111.9, 59.9. HRMS (EI) calcd
for C17H14N2OS [M]+ 294.0827, found 294.0823.
1-Propargyl-3-methoxypyridin-2-one (13). To a stirring solution
of 3-methoxy-2-pyridinone (1.00 g, 8.00 mmol) in DMF (25 mL) was
added propargyl bromide (80 wt % solution in toluene, 1.5 equiv) and
K2CO3 (3.313 g, 24 mmol). The reaction mixture was heated
overnight at 100 °C and allowed to cool to room temperature. The
reaction was partitioned between EtOAc (120 mL) and water (100
mL). The organic layer was separated, washed repeatedly with water
(7 × 100 mL) and brine (60 mL) and dried on Na2SO4. Solvent was
evaporated in vacuo, and the dark-brown crude was purified by column
chromatography using a gradient of 0−20% acetone in CH2Cl2 to give
13 (0.79 g, 60%) as a brownish solid. 1H NMR (CDCl3, 400 MHz) δ
2.36 (1H, t, J = 2.8), 3.67 (3H, m), 4.66 (1H, d, J = 2.8), 6.05 (1H, t, J
= 7.2), 6.50 (1H, dd, J = 1.6, 7.2), 7.11 (1H, dd, J = 1.6, 6.8). 13C
NMR (CDCl3, 100 MHz) δ 37.2, 55.5, 74.6, 77.3, 104.8, 112.0, 126.3,
149.4, 157.1. HRMS (EI) calcd for C9H9NO2 [M]+ 163.0633, found
163.0636
1-(4-Dimethylamino)phenylltriazolylmethyl-3-methoxypyridin-2-
thione (16b). The reaction of 14b (0.08 g, 0.25 mmol) and
Lawesson’s reagent (0.06 g, 0.15 mmol) in toluene (8 mL) within
12 h as described for the synthesis of 10a gave compound 16b (0.07 g,
1
84%) as a yellow solid. H NMR (400 MHz, cdcl3) δ 8.36 (s, 1H),
7.81 (dd, J = 6.4, 1.5 Hz, 1H), 7.46 (m, 2H), 6.66 (m, 4H), 6.01 (s,
2H), 3.87 (s, 3H), 2.97 (s, 6H). 13C NMR (100 MHz, CDCl3) δ
171.8, 158.9, 150.4, 141.5, 132.4, 126.3, 122.5, 121.8, 112.1, 112.0,
110.1, 56.7, 51.2, 40.3. HRMS (EI) calcd for C17H19N5OS [M]+
314.1310, found 314.1304.
1-Phenyltriazolylmethyl-3-hydroxypyridin-2-thione (17a). The
reaction of 16a (0.28 g, 0.93 mmol) and 1 M BBr3 in CH2Cl2 (1.5
equiv) within 48 h as described for the synthesis of 11a gave
compound 17a (0.18 g, 67%) as a green solid. Retention time 8.63
min (solvent gradient: 40−80% solvent B in 20 min then constant
1-Phenyltriazolylmethyl-3-methoxypyridin-2-one (14a). Com-
pound 13 (0.32 g, 1.95 mmol) and phenylazide (0.35 g, 2.93 mmol)
were dissolved in anhydrous THF (10 mL) and stirred under argon at
room temperature. Copper(I) iodide (0.01 g, 0.07 mmol) and Hunig’s
base (0.1 mL) were added to the reaction mixture, and stirring
continued for 4 h. The reaction mixture was diluted with CH2Cl2 (40
mL) and washed with 1:4 NH4OH/saturated NH4Cl (3 × 30 mL) and
saturated NH4Cl (30 mL). The organic layer was dried over Na2SO4
and concentrated in vacuo. The crude product was triturated with
hexanes to give 14a (510 mg, 92%) as a white solid. 1H NMR (CDCl3,
1
80% B for 5 min). H NMR (400 MHz, CDCl3) δ 8.43 (d, J = 16.6
Hz, 1H), 8.39 (s, 1H), 7.79 (dd, J = 6.6, 1.3 Hz, 1H), 7.69 (m, 2H),
7.46 (m, 3H), 6.97 (dd, J = 7.7, 1.2 Hz, 1H), 6.69 (dd, J = 7.6, 6.8 Hz,
1H), 5.94 (s, 2H). 13C NMR (100 MHz, CDC3) δ 168.6, 155.1, 141.6,
136.7, 131.7, 129.7, 129.0, 122.6, 120.6, 114.0, 112.5, 77.3, 77.0, 76. 7,
52.1. HRMS (EI) calcd for C14H12N4OS [M]+ 284.0730, found
284.0732.
1-(4-Dimethylamino)phenylltriazolylmethyl-3-hydroxypyridin-2-
thione (17b). The reaction of 16b (0.07 g, 0.21 mmol) and 1 M BBr3
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in CH2Cl2 (0.64 mL, 1.5 equiv) within 48 h as described for the
synthesis of 11a gave compound 17b (0.03 g, 48%) as a green solid.
Retention time 8.43 min (solvent gradient: 40−80% solvent B in 20
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min then constant 80% B for 5 min). H NMR (400 MHz, CDCl3) δ
8.42 (s, 1H), 8.29 (d, J = 11.5 Hz, 1H), 7.79 (d, J = 6.4 Hz, 1H), 7.50
(m, 2H), 6.98 (dd, J = 36.5, 28.9 Hz, 2H), 6.72 (m, 3H), 5.94 (s, 2H),
3.01 (d, J = 2.7 Hz, 6H). 13C NMR (100 MHz, CDCl3) δ 155.1, 150.7,
141.1, 131.7, 127.7, 126.3, 122. 5, 122.0, 114.0, 112.5, 112.2, 52.2, 40.4.
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ASSOCIATED CONTENT
■
S
* Supporting Information
1H NMR and 13C NMR spectral information, solubility data
and molecular modeling outputs. This material is available free
of charge via the Internet at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*For M.M.: phone, 847-467-0472; fax, 847-467-3057; E-mail,
milan.mrksich@northwestern.edu. For A.K.O.: phone, 404-894-
4047; fax, 404-894-2291; E-mail, aoyelere@gatech.edu.
■
Author Contributions
∥These authors contributed equally to the manuscript.
Notes
The authors declare no competing financial interest.
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Michaelides, M. R.; Li, J.; Pease, L. J.; Glaser, K. B.; Marcotte, P. A.;
Bouska, J. J.; Murphy, S. S.; Davidsen, S. K. Trifluoromethyl ketones as
inhibitors of histone deacetylase. Bioorg. Med. Chem. Lett. 2002, 12
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ACKNOWLEDGMENTS
■
We are grateful to Professor Olaf Wiest for providing us with
the HDAC 1 homology model. This work was financially
supported by NIH grants R01CA131217 (A.K.O.) and
R01GM084188 (M.M.). Q.H.S. is a recipient of a GAANN
predoctoral fellowship from the Georgia Tech Center for Drug
Design, Development, and Delivery. We are grateful to the ACS
for a Division of Medicinal Chemistry travel award to V.P.
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Metalloproteinase Inhibitors and CancerTrials and Tribulations.
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Konigsmann, M.; Breuer, E. Carbamoylphosphonate-based matrix
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A.; Nolan, K. B. Metal complexes of salicylhydroxamic acid (H2Sha),
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molecular structure of [Cu(phen)2(Cl)]Cl·H2Sha, a model for a
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ABBREVIATIONS USED
■
HDAC, histone deacetylase; HAT, histone acetyltransferase;
HDACi, histone deacetylase inhibitors; ZBG, zinc binding
group; SAHA, suberoylanilide hydroxamic acid; TSA, trichos-
tatin A; 3HPT, 3-hydroxypyridin-2-thione; MMP, matrix
metalloproteins
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