Synthesis and structure-affinity relationships of novel dibenzylideneacetone derivatives as probes for ?-Amyloid Plaques

Article abstract of DOI:10.1021/jm101404k

A new and extensive set of dibenzylideneacetone derivatives was synthesized and screened for affinity toward A_1-42 aggregates. Structure-activity relationships revealed the binding of dibenzylideneacetones to be affected by various substituents. The introduction of a substituent group in the ortho position reduced or abolished the binding. However, the para position was highly tolerant of sterically demanding substitutions. Three radioiodinated ligands (6, 70, and 71) and two ¹⁸F fluoro-pegylated (FPEG) ligands (83 and 85) were prepared, all of which displayed high affinity for A_1-42 aggregates (K_i ranging from 0.9 to 7.0 nM). In biodistribution experiments, they exhibited good initial penetration (1.59, 4.68, 4.56, 4.13, and 5.15% ID/g, respectively, at 2 min) of and fast clearance from the brain. Autoradiography with sections of postmortem AD brain and transgenic mouse brain confirmed the high affinity of these tracers. These preliminary results strongly suggest the dibenzylideneacetone structure to be a potential new scaffold for β-amyloid imaging probes.

Full text of DOI:10.1021/jm101404k

ARTICLE
pubs.acs.org/jmc
Synthesis and StructureꢀAffinity Relationships of Novel
Dibenzylideneacetone Derivatives as Probes for β-Amyloid Plaques
Mengchao Cui,†,‡ Masahiro Ono,*,† Hiroyuki Kimura,† Boli Liu,‡ and Hideo Saji*,†
†Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida Shimoadachi-cho, Sakyo-ku, Kyoto 606-8501, Japan
‡Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University,
Beijing 100875, People's Republic of China
S Supporting Information
b
ABSTRACT: A new and extensive set of dibenzylideneacetone
derivatives was synthesized and screened for affinity toward
Aβ1ꢀ42 aggregates. Structureꢀactivity relationships revealed
the binding of dibenzylideneacetones to be affected by various
substituents. The introduction of a substituent group in the ortho position reduced or abolished the binding. However, the para
position was highly tolerant of sterically demanding substitutions. Three radioiodinated ligands (6, 70, and 71) and two 18F fluoro-
pegylated (FPEG) ligands (83 and 85) were prepared, all of which displayed high affinity for Aβ1ꢀ42 aggregates (Ki ranging from 0.9
to 7.0 nM). In biodistribution experiments, they exhibited good initial penetration (1.59, 4.68, 4.56, 4.13, and 5.15% ID/g,
respectively, at 2 min) of and fast clearance from the brain. Autoradiography with sections of postmortem AD brain and transgenic
mouse brain confirmed the high affinity of these tracers. These preliminary results strongly suggest the dibenzylideneacetone
structure to be a potential new scaffold for β-amyloid imaging probes.
’ INTRODUCTION
carbon-11 (20.4 min) limits the potential clinical use of this agent.
Great efforts have been made to develop imaging agents labeled
with a longer half-life isotope, fluorine-18 (109.4 min). An
analogue of PIB, [18F]-2-(3-fluoro-4-(methylamino)phenyl)
benzo[d]thiazol-6-ol ([18F]GE-067),15 and the stilbene deriva-
tives [18F]-4-(N-methylamino)-40-(2-(2-(2-fluoroethoxy)ethoxy)
ethoxy)-stilbene ([18F]BAY94-9172)16 and [18F]-(E)-4-(2-
(6-(2-(2-(2-fluoroethoxy)ethoxy)ethoxy)pyridin-3-yl)vinyl)-N-
methylaniline ([18F]AV-45)17,18 are under commercial develop-
ment for the mapping of Aβ plaque burden in living brain tissue.
In addition, [123I]-6-iodo-2-(40-dimethylamino-)phenyl-imidazo
[1,2]pyridine ([123I]IMPY)19ꢀ21 is the first SPECT probe to be
evaluated in humans. The preliminary clinical data showed a
poor signal-to-noise ratio, making it difficult to distinguish AD
patients. Currently, some research groups have continued to
develop more useful probes for the SPECT imaging of cerebral
Aβ plaques.22ꢀ24
Almost all of the agents evaluated in humans have been
developed based on thioflavin T (ThT) and Congo Red (CR),
dyes used for Aβ plaques in sections of AD brain. Aβ plaques are
known to have various binding sites for ligands,25 and numerous
Aβ-binding compounds besides ThT and CR derivatives have
been reported. The application of these new compounds to
PET/SPECT imaging should contribute to the development of
new probes with improved properties including higher affinity
for Aβ plaques and less nonspecific binding in the white matter of
the brain. Indeed, we have found that flavonoids such as
Alzheimer's disease (AD) is an irreversible, progressive brain
disorder that accounts for the majority of dementia cases.
Histopathologically, AD is characterized by β-amyloid (Aβ)
plaques composed mainly of mis-folded Aβ peptides and neuro-
fibrillary tangles (NFTs) containing hyperphosphorylated τ
protein.1,2 However, the precise molecular mechanisms leading
to AD remain unknown. Several theories have arisen, with the
amyloid cascade hypothesis perhaps the most prominent.3,4
Moreover, a refined version of the amyloid cascade hypothesis
proposes that soluble Aβ peptides (soluble oligomers or proto-
fibrils), not mature Aβ plaques, exert toxic effects on neuronal
cells.5,6 The clinical diagnosis of AD is primarily based on
neurological observations and patient history and is often difficult
and unreliable. Although there is a lack of correlation between
cognitive decline and elevated levels of Aβ plaques in the brain,7,8
several reports indicate that overaccumulation of Aβ peptides
initiates a sequence of events that lead to neurodegeneration.9,10
Therefore, Aβ plaques could be considered a biomarker for the
early diagnosis of AD.
With the assistance of nuclear imaging techniques such as
positron emission tomography (PET) and single photon emission
computed tomography (SPECT), radionuclide-labeled agents
targeting Aβ plaques in the brain may greatly facilitate the
diagnosis of AD.11,12 Over the past 10 years, several agents for
imaging Aβ plaques have been tested in humans (Figure 1).
Pittsburgh compound B, 2-(40-[11C]methylaminophenyl)-6-
hydroxybenzothiazole ([11C]PIB), is, to date, the most widely used
PET radioligand for amyloid imaging13,14 and clearly distinguishes
between AD and control cases. However, the short half-life of
Received: October 28, 2010
Published: March 21, 2011
r
2011 American Chemical Society
2225
dx.doi.org/10.1021/jm101404k J. Med. Chem. 2011, 54, 2225–2240
|

Journal of Medicinal Chemistry
ARTICLE
Figure 1. Chemical structure of Aβ imaging probes used in clinical trials.
Scheme 1a
a Reagents and conditions: (a) NaOH (1 M), acetone, room temperature. (b) NaOMe (28% in MeOH), EtOH, substituted benzaldehyde, room
temperature. (c) SnCl2, EtOH, HCl, reflux. (d) K2CO3, CH3I, room temperature.
flavone,26,27 chalcone,28,29 and aurone30,31 strongly bind to Aβ plaques
and applied them as new PET/SPECT probes (Figure 2). However,
there is still a need for novel molecular scaffolds to serve in smart
Aβ probes. Furthermore, many basic scientific questions regard-
ing how these small organic molecular probes attach to amyloid
fibrils remain to be answered. Elucidation of the mode of binding
between Aβ aggregates and small ligands may enable the rational
molecular design of more useful imaging probes in the future.
In 2006, Ryu et al. reported a [18F]-fluoropropyl-substituted
curcumin derivative, 1-[4-(3-[18F]fluoropropoxy)-3-methoxy-
phenyl]-5-hydroxy-7-(4-hydroxy-3-methoxyphenyl)-1,4,6-hep-
tatrien-3-one, as a specific Aβ probe with high affinity (0.07 nM
using [125I]-1-iodo-2,5-bis(3-hydroxycarbonyl-4-methoxy)styryl-
benzene ([125I]IMSB) as the radiolabeled standard). However,
its poor penetration of the brain together with instability in vivo
hampered its potential clinical use (0.52% ID/g at 2 min and
0.11% ID/g at 30 min). Studies indicated that this derivative was
quickly converted to an unidentified polar product, which cannot
cross the bloodꢀbrain barrier (BBB).32 Several papers demon-
strated that the β-diketone moiety (methylene moiety) in the
middle of curcumin's structure is responsible for the instability
and poor pharmacokinetic profile under physiological condi-
tions.33 In addition, the decomposition of curcumin can occur as
a result of exposure to light, a process also mediated by the active
methylene moiety.34,35
To improve the pharmacokinetic profile of curcumin, mod-
ifications to the middle of the compound that lead to a
dibenzylideneacetone structure lacking an active methylene
2226
dx.doi.org/10.1021/jm101404k |J. Med. Chem. 2011, 54, 2225–2240

Journal of Medicinal Chemistry
ARTICLE
moiety and one carbonyl moiety but maintaining the two
aromatic rings responsible for the binding of Aβ plaques were
explored. Such dibenzylideneacetone derivatives can be simply
obtained by a one-pot reaction.
In the present study, a series of dibenzylideneacetones with
various substitutents were synthesized and screened for Aβ
binding. We examined the possible structureꢀactivity relation-
ship (SAR) of these analogues using substitutions on the aryl
rings, believing the SAR results would allow for a more rational
design of ligands. Three radioiodinated and two 18F FPEG
(fluoro-pegylated) derivatives with high affinity for Aβ aggre-
gates were evaluated in vitro and in vivo as potential probes for
PET or SPECT.
Scheme 2a
’ RESULTS AND DISCUSSION
Chemistry and Radiochemistry. The core structure of the
dibenzylideneacetones was produced as shown in Schemes 1ꢀ3.
The key step was the base-catalyzed Claisen condensation
reaction starting from suitably substituted aromatic aldehydes
and aliphatic ketones. The unsymmetrical dibenzylideneace-
tones (2ꢀ9, 12ꢀ22, 26ꢀ29, 32ꢀ57, and 68ꢀ71) were ob-
tained in 3ꢀ85% yields, and the symmetric compounds
(58ꢀ64) were obtained in 12ꢀ88% yields. The amino-substi-
tuted compounds 10, 23, 30, and 66 were produced by reducing
the nitro group using SnCl2. Subsequent methylation of the
amino group using methyl iodide afforded mono- or dimethy-
lated derivatives (11, 24, 25, 31, and 67). The tributyltin
precursors (72ꢀ74) were prepared from the corresponding
bromo compounds (5, 68, and 69) in a bromo to tributyltin
exchange reaction catalyzed by (Ph3P)4Pd (yield, 22.9ꢀ30.2%).
The FPEG dibenzylideneacetones 81ꢀ83 and 85 were prepared
by the procedures shown in Schemes 4 and 5. To prepare
compounds with different numbers of ethoxy units as the linkage,
the dimethylated derivative 1 or monomethylated derivative 67
was coupled with the polyethyleneglycol-modified benzaldhyde
to obtain 75ꢀ77 and 86, respectively. For the dimethylated
dibenzylideneacetone, tosylation of the free hydroxyl groups
present in 75ꢀ77 afforded the precursor 78ꢀ80, which readily
reacted with anhydrous tetra-n-butylammonium fluoride
(TBAF) at reflux to give the “cold” FPEG dibenzylideneace-
tones, 81ꢀ83 (Scheme 4). For the monomethylated dibenzyli-
deneacetone, the hydroxy group in 86 was subsequently
protected with tert-butyldimethylsilyl chloride (TBDMSCl) to
give the TBS-protected compound 87. Compound 88 was
obtained by protecting the methylamino group of 87 with
a Reagents and conditions: (a) NaOMe (28% in MeOH), EtOH,
substituted aromatic aldehyde, room temperature. (b) NaOMe (28%
in MeOH), EtOH, room temperature.
Scheme 3a
a Reagents and conditions: (a) (1) K2CO3, acetone, room temperature; (2) HCl, room temperature. (b) SnCl2, EtOH, HCl, reflux. (c) K2CO3, CH3I,
room temperature. (d) NaOMe (28% in MeOH), EtOH, 4-bromobenzaldehyde, room temperature. (e) (Bu3Sn)2, (Ph3P)4Pd, toluene, reflux. (f)
NaOMe (28% in MeOH), EtOH, 4-iodobenzaldehyde, room temperature. (g) [125I]NaI, HCl (1 M), H2O2 (3%).
2227
dx.doi.org/10.1021/jm101404k |J. Med. Chem. 2011, 54, 2225–2240

Journal of Medicinal Chemistry
ARTICLE
Scheme 4a
a Reagents and conditions: (a) NaOMe (28% in MeOH), EtOH, 1, room temperature. (b) TsCl, pyridine, room temperature. (c) THF, TBAF (1 M),
reflux. (d) K222, [18F]ꢀ, DMSO, 120 °C.
Scheme 5a
a Reagents and conditions: (a) DAST, CHCl3, ꢀ78 °C. (b) NaOMe (28% in MeOH), EtOH, 67, room temperature. (c) TBDMSCl, imidazole, DCM,
room temperature. (d) (BOC)2O, THF, reflux. (e) THF, TBAF (1 M), reflux. (f) MsCl, Et3N, DCM, room temperature. (g) (1) K222, [18F]ꢀ, DMSO,
120 °C; (2) HCl (1 M), 120 °C.
butyloxycarbonyl (BOC). After removal of the TBS-protecting
group of 88 with TBAF, the free hydroxyl group was converted
into mesylates by reacting with methanesulfonyl chloride in the
presence of triethylamine to give 89. The “cold” fluorinated
compound 85 was successfully obtained by stirring 67 and the
FPEG benzaldhyde 84 in ethanol (Scheme 5).
precursor. After 5 min at 120 °C, the mixture was treated with
aqueous HCl to remove the N-BOC-protecting group. The
crude product was purified by HPLC (radiochemical purity
>98%, radiochemical yield 13%, decay corrected).
SAR Analysis. The affinity of these dibenzylideneacetone deriv-
atives (2ꢀ64, 70, 71, 81ꢀ83, and 85) for Aβ1ꢀ42 aggregates was
examined with competition binding assays using [125I]IMPY as
the competing radioligand. IMPY and curcumin were also
screened using the same system for comparison. The results
are listed in Table 1. Dibenzylideneacetone (58) without any
substituents showed moderate affinity (Ki = 242.5 ( 42.8 nM).
Introducing Cl or methoxy groups at the para position on both
phenyl rings to form symmetrical ligands increased the binding
(e.g., 59, Ki = 9.0 ( 1.2 nM; 60, Ki = 6.5 ( 1.2 nM), especially for
12 with two N,N-dimethylamino groups (Ki = 2.7 ( 0.6 nM),
whose affinity increased about 90-fold. As compared with 58, 61
with a cyclohexanone spacer in the middle showed a decrease in
affinity (Ki = 704.3 ( 90.3 nM). A comparable increase in
binding was also observed on introducing Cl (62, Ki = 11.4 ( 0.8
nM), methoxy (63, Ki = 24.8 ( 2.5 nM), or N,N-dimethylamino
(64, Ki = 1.0 ( 0.3 nM) groups for these symmetrical dibenzy-
lidenecyclohexanones. These observations demonstrated again
that the N,N-dimethylamino moiety plays a critical role in
maintaining affinity for Aβ aggregates.
The radioiodinated ligands [125I]6, 70, and 71 were prepared
from the corresponding tributyltin precursors through an iodo-
destannylation reaction using hydrogen peroxide as an oxidant
with radiochemical yield of 27.6, 15.3, and 24.1%, respectively
(Scheme 3). After purification by high-performance liquid
chromatography (HPLC), the radiochemical purity of these
radiotracers was greater than 98%. The specific activity of the
no carrier-added preparation was comparable to that of Na125I,
2200 Ci/mmol. Finally, the radiochemical identities of [125I]6,
70, and 71 were verified using HPLC by coinjection with the
nonradioactive compounds. To make the desired 18F-labeled
dibenzylideneacetone [18F]83, the tosylate precursor 80 was
mixed with [18F]fluoride/potassium carbonate and Kryptofix
222 in dimethyl sulfoxide (DMSO) under heating at 120 °C for 5
min. The mixture was loaded on a Sep-Pak Plus-C18 cartridge
(Waters), and the elution was purified by HPLC (radiochemical
purity >98%, radiochemical yield 49%, decay corrected). For
[18F]85, the N-BOC-protected mesylate 90 was employed as the
2228
dx.doi.org/10.1021/jm101404k |J. Med. Chem. 2011, 54, 2225–2240

Journal of Medicinal Chemistry
ARTICLE
Table 1. Inhibition Constants (Ki, nM) for Binding to
Aggregates of Aβ1-42 versus [125I]IMPY
compound Ki (nM)a compound Ki (nM)a compound Ki (nM)a
2
1.2 ( 0.2
3.7 ( 0.9
1.1 ( 0.2
2.8 ( 0.5
0.9 ( 0.2
6.8 ( 1.6
0.7 ( 0.1
5.2 ( 1.1
3.7 ( 0.4
2.9 ( 0.5
2.7 ( 0.6
78.1 ( 8.5
0.8 ( 0.2
1.3 ( 0.2
15.7 ( 3.9
131.2 ( 20.3
2.0 ( 0.2
1.2 ( 0.1
1.9 ( 0.3
5.5 ( 1.7
4.0 ( 1.4
13.7 ( 3.4
8.1 ( 1.4
8.0 ( 0.6
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
18.6 ( 8.1 50
0.9 ( 0.1 51
28.2 ( 5.1 52
18.8 ( 3.0 53
8.4 ( 3.0 54
2636.5 ( 140.8 55
18.5 ( 0.9 56
9.2 ( 1.0 57
4.0 ( 0.5 58
5.4 ( 0.9 59
4.7 ( 2.1 60
2.8 ( 0.8 61
5.2 ( 0.6 62
39.1 ( 4.8 63
4.1 ( 0.4 64
16.2 ( 5.1 70
3.8 ( 1.1 71
33.3 ( 3.8 81
2.8 ( 0.4 82
2.2 ( 0.3 83
2.3 ( 0.1 85
4.8 ( 1.3 IMPY
23.0 ( 1.6
8.5 ( 0.8
5.3 ( 0.5
3
4
3.8 ( 0.4
5
11.7 ( 1.1
1.8 ( 0.2
6
7
4.2 ( 0.4
8
2.5 ( 0.2
9
21.1 ( 1.2
242.5 ( 42.8
9.0 ( 1.2
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
6.5 ( 1.2
704.3 ( 90.3
11.4 ( 0.8
24.8 ( 2.5
1.0 ( 0.3
7.0 ( 2.2
2.8 ( 0.5
5.6 ( 2.5
4.4 ( 1.3
Figure 4. Autoradiography of [18F]83 and [18F]85 in vitro in Tg model
mouse (C57BL6-APP/PS1, 12 months old, male) brain sections (A and E)
and control sections (B and F). The presence and distribution of plaques
in the sections were confirmed with thioflavin-S (C and G). Arrows
show the correspondence to Aβ plaques.
6.9 ( 1.4
8.6 ( 1.3
10.5 ( 1.0
49.8 ( 8.0
0.20 ( 0.06b
curcumin
5.8 ( 1.2
a Measured in triplicate with results given as the mean ( SD. b Data from
ref 32.
Figure 2. New backbone structures as Aβ imaging probes.
Figure 5. Autoradiography of [18F]83 and [18F]85 in vitro in AD brain
sections and control sections (temporal lobe) (A, C, E, and F). The
presence and distribution of plaques in the sections were confirmed with
immunohistochemical staining using a monoclonal Aβ antibody (B, D,
and G).
An extensive set of unsymmetrical dibenzylideneacetones with
a N,N-dimethylamino group were synthesized. In general, the
methylation of a primary amino group to form a secondary amino
or tertiary amino group increased the affinity [e.g., 6 > 71 > 70
(para position); 12 > 11 > 10 (para position); 25 > 24 > 23
Figure 3. Autoradiography of [125I]6 and [125I]70 in vitro in AD brain
sections (temporal lobe) (A and C). The presence and distribution of
plaques in the sections were confirmed with immunohistochemical
staining using a monoclonal Aβ antibody (B and D).
2229
dx.doi.org/10.1021/jm101404k |J. Med. Chem. 2011, 54, 2225–2240

Journal of Medicinal Chemistry
ARTICLE
Table 2. Biodistribution of in ddY Normal Mice after iv Injections of [125I]Tracers (% ID/g, Mean ( SD, n = 4)
organ
2 min
15 min
30 min
60 min
120 min
[
125I]6 (Log D = 3.66 ( 0.09)
blood
11.62 ( 1.22
1.59 ( 0.04
6.42 ( 0.80
44.64 ( 6.19
11.59 ( 1.10
24.45 ( 1.67
15.86 ( 1.37
1.16 ( 0.15
1.38 ( 0.38
11.56 ( 2.61
6.58 ( 2.15
1.11 ( 0.28
2.69 ( 0.85
32.80 ( 5.01
9.94 ( 2.07
12.97 ( 3.05
22.23 ( 5.52
1.75 ( 0.15
7.38 ( 2.75
14.93 ( 1.09
3.98 ( 0.28
0.63 ( 0.03
1.62 ( 0.20
24.64 ( 2.85
12.26 ( 3.95
6.91 ( 1.32
15.63 ( 1.71
1.85 ( 0.27
11.62 ( 3.42
26.77 ( 1.41
2.16 ( 0.55
0.28 ( 0.03
1.03 ( 0.24
11.54 ( 0.60
6.28 ( 2.87
3.64 ( 0.47
7.00 ( 2.62
0.61 ( 0.24
7.68 ( 2.53
23.53 ( 6.25
2.29 ( 0.65
0.26 ( 0.07
1.19 ( 0.17
16.47 ( 1.38
7.34 ( 0.67
3.35 ( 0.12
8.55 ( 1.98
0.77 ( 0.29
17.65 ( 2.91
32.22 ( 1.13
brain
heart
liver
spleen
lung
kidney
stomacha
intestine
thyroid
[
125I]71 (Log D = 3.55 ( 0.02)
blood
brain
7.48 ( 0.81
4.68 ( 0.25
8.11 ( 1.74
39.22 ( 4.48
4.57 ( 0.55
9.67 ( 1.12
14.73 ( 2.23
3.26 ( 1.37
3.53 ( 1.19
18.20 ( 2.65
6.02 ( 1.80
2.62 ( 0.22
4.14 ( 1.36
40.83 ( 4.21
3.36 ( 0.14
7.42 ( 2.95
16.49 ( 3.52
3.82 ( 0.67
10.33 ( 4.30
28.09 ( 4.45
4.84 ( 1.40
1.38 ( 0.23
3.29 ( 1.42
23.88 ( 4.99
2.22 ( 0.94
6.18 ( 2.58
15.54 ( 5.56
3.17 ( 0.97
13.19 ( 5.85
27.78 ( 10.74
3.35 ( 0.90
0.71 ( 0.06
1.74 ( 0.73
22.63 ( 3.73
1.52 ( 0.38
3.50 ( 0.70
10.46 ( 2.92
3.34 ( 0.93
23.62 ( 3.87
23.96 ( 3.78
4.46 ( 0.92
0.54 ( 0.09
1.91 ( 0.60
27.83 ( 2.15
1.23 ( 0.23
3.90 ( 0.73
13.43 ( 4.53
4.49 ( 0.82
41.29 ( 9.04
72.93 ( 10.03
heart
liver
spleen
lung
kidney
stomacha
intestine
thyroid
[
125I]70 (Log D = 3.26 ( 0.05)
blood
brain
3.89 ( 0.34
4.56 ( 0.42
7.06 ( 1.37
16.98 ( 2.29
2.80 ( 0.15
9.25 ( 1.09
11.20 ( 0.10
1.37 ( 0.37
2.27 ( 0.17
8.64 ( 2.19
4.93 ( 1.91
2.37 ( 0.32
3.45 ( 0.59
29.08 ( 4.93
2.02 ( 0.41
6.06 ( 1.18
22.81 ( 3.42
3.10 ( 2.24
6.90 ( 2.44
8.39 ( 0.51
4.12 ( 0.33
1.36 ( 0.19
2.01 ( 0.30
24.17 ( 4.15
1.79 ( 0.17
4.81 ( 0.43
16.31 ( 1.81
3.12 ( 0.92
10.85 ( 3.68
11.49 ( 3.53
1.72 ( 0.58
0.54 ( 0.12
0.83 ( 0.17
16.43 ( 2.32
0.80 ( 0.14
2.43 ( 0.76
9.00 ( 1.67
2.12 ( 0.62
25.97 ( 4.93
14.14 ( 4.83
2.52 ( 0.19
0.40 ( 0.07
1.11 ( 0.09
17.57 ( 1.63
1.13 ( 0.39
2.82 ( 0.16
9.52 ( 0.79
3.07 ( 0.58
25.70 ( 1.48
21.98 ( 3.75
heart
liver
spleen
lung
kidney
stomacha
intestine
thyroid
a Expressed as % injected dose per organ.
(meta position)], which is consistent with previous data on
primary, secondary, and tertiary amino ligands.12,36 In contrast,
methylation of the amino group at the ortho position reduced the
binding affinity dramatically [e.g., 31 (Ki = 2636.5 ( 140.8 nM)
. 30 (Ki = 8.4 ( 3.0 nM)], which we will discuss later.
binding properties. Interestingly, increasing the size of the
substutient at the aromatic amino group decreased the binding
affinity, as reflected in 16 with a N,N-diethylamino group (Ki =
15.7 ( 3.9 nM) and 17 with a N,N-diphenylamino group (Ki =
131.2 ( 20.3 nM).
Increasing the size of the substituent at the para position does
not affect the affinity for Aβ aggregates. The ligands 18 and 40
with a benzyloxy group showed Ki values of 2.0 ( 0.2 and 4.1 (
0.4 nM, respectively, and 44 with a bulky trityloxy group also
showed high affinity (Ki = 2.8 ( 0.4 nM). These results show
high tolerance for steric bulk at this position. For the purpose of
developing PET or SPECT agents targeting Aβ plaques, this
finding regarding the dibenzylideneacetone scaffold is important.
For example, a large chelating structure is necessary for techne-
tium-99 m, and a long polyethylene glycol chain is adapted in the
design of fluorine-18.18,37,38 Indeed, the FPEG ligands 81ꢀ83
and 85 with different numbers of polyethylene glycol units (n =
1ꢀ3) all show excellent affinity (Ki < 10 nM), and the length of
the linkage did not bring about an appreciable change in the
The ligands with both electron-withdrawing substituents [e.g.,
F (3 and 19), NO2 (9 and 22), and CF3 (14)] and electron-
donating substituents [e.g., OCH3 (8) and N(CH3)2 (12 and
25)] at the para or meta position showed high affinity for Aβ
aggregates, except for 13 with a carboxyl group (Ki = 78.1 ( 8.5
nM). Tolerance for steric bulk at the meta position was also
observed, as the binding was not affected when different substit-
uents were introduced [e.g., 3,5-(CF3)2 (34), 3,5-(OCH3)2
(36), and 3-phenoxy (42)]. In comparison, ligands with substit-
uents at the ortho position showed less affinity for Aβ aggregates
(Ki > 8 nM, e.g., 26, 28ꢀ33, 39, 41, and 43) except for 27. This
may be due to the steric effects that arise between the ortho
subsituents and the hydrogen atom on the carbonꢀcarbon
double bond, and the coplanar geometry of the conjugation π
2230
dx.doi.org/10.1021/jm101404k |J. Med. Chem. 2011, 54, 2225–2240

Journal of Medicinal Chemistry
ARTICLE
system may be disrupted. As compared with 30, the analogue
with a N-methylamino group at the ortho position (31) exhibited
greater steric effects, resulting in a loss of affinity.
Table 3. Biodistribution of [18F]83 and [18F]85 in ddY
Normal Mice (% ID/g, Mean ( SD, n = 4)
organ
2 min
15 min
30 min
60 min
When a phenyl ring in the dibenzylideneacetone structure is
changed to a heterocyclic ring, such as a thiophene, furan,
pyridine, or pyrrole ring, the ligands also show high affinity, as
reflected in 44ꢀ55. Use of a naphthalenyl group instead of the
phenyl group (56) had little effect on binding affinity, consistent
with the proposed πꢀπ interaction between ligands and Aβ
fibers. There are distinct binding sites for CR and ThT on Aβ
aggregates, which were clearly differentiated by Kung et al.39
These two ligands did not inhibit each other, indicating that the
two sites on Aβ aggregates are nonoverlapping.
[
18F]83 (Log D = 2.97 ( 0.12)
brain
4.13 ( 0.41
5.38 ( 0.32
2.88 ( 0.37
1.51 ( 0.17
3.89 ( 0.36
2.42 ( 0.14
1.04 ( 0.23
2.46 ( 0.54
2.08 ( 0.54
14.07 ( 1.94
7.13 ( 2.64
4.46 ( 0.80
6.00 ( 1.14
0.90 ( 0.14
1.60 ( 0.17
2.33 ( 0.30
6.88 ( 1.51
3.67 ( 0.85
1.93 ( 0.67
3.98 ( 1.52
blood
bone
liver
22.32 ( 3.12 24.41 ( 3.34
kidney
spleen
stomacha
intestine
lung
12.95 ( 0.79
4.26 ( 1.05
6.28 ( 5.75
4.12 ( 0.48
12.30 ( 1.99
7.60 ( 1.32
12.77 ( 2.42
6.19 ( 1.06
7.39 ( 1.87
10.53 ( 2.11
6.34 ( 0.88
3.33 ( 0.35
A previous study using [125I]IMSB as the radioligand showed
that curcumin derivatives bound to Aβ aggregates at the CR site
(curcumin, Ki = 0.20( 0.06nM; fluoropropyl-curcumin, Ki = 0.07
( 0.01).32 However, in the present study, most of the dibenzy-
lideneacetone ligands inhibited the binding of [125I]IMPY to
Aβ1ꢀ42 aggregates, indicating that they attach at the ThT-binding
site. We consider the distance between the two phenyl rings
important to the selection of the binding site. After removal of the
active methylene moiety and one carbonyl moiety in the middle of
curcumin, the distance between the two phenyl rings decreases,
resulting in a change of the binding site.
17.50 ( 4.47 21.57 ( 7.37
3.38 ( 0.43
1.90 ( 0.26
1.86 ( 0.25
1.47 ( 0.13
heart
[
18F]85 (Log D = 3.08 ( 0.05)
brain
5.15 ( 0.17
7.44 ( 1.22
2.97 ( 0.35
1.89 ( 0.17
7.99 ( 0.34
2.93 ( 0.37
1.35 ( 0.19
4.68 ( 0.59
2.94 ( 0.91
1.27 ( 0.12
3.59 ( 0.93
2.54 ( 0.84
blood
bone
liver
24.15 ( 5.77 30.09 ( 4.43
19.24 ( 3.64 14.07 ( 1.87
kidney
spleen
stomacha
intestine
lung
16.48 ( 2.51
5.39 ( 1.79
3.26 ( 0.63
6.58 ( 0.89
12.19 ( 2.31
10.55 ( 1.10
14.15 ( 0.98 11.51 ( 1.76 9.43 ( 1.50
6.62 ( 0.42
2.61 ( 0.18
12.82 ( 3.23
11.77 ( 1.94
7.64 ( 1.23
5.44 ( 1.24
1.93 ( 0.33
5.35 ( 2.06
1.28 ( 0.49
Biological Evaluation. As compared with the binding of
IMPY to Aβ1ꢀ42 aggregates (Ki = 10.5 nM), the affinity of
iodinated compounds (71, 70, and 6) with primary, secondary,
and tertiary amine groups and FPEG compounds (83 and 85, n = 3)
was superior, and these compounds were evaluated further.
The binding of these radiolabeled tracers to Aβ plaques in
sections of brain tissue from AD patients or transgenic (Tg)
model mice (APP/PS1) was evaluated by in vitro autoradiogra-
phy. As shown in Figure 3A,C, two of the radioiodinated probes
(6 and 71) exhibited intensive labeling of plaques showing a
strong signal in the cortex region and a low background level in
white matter in the AD brain sections. The hot spots of radio-
activity were consistent with the results of immunohistochemical
staining in vitro in the same sections using the Aβ antibody BC05
(Figure 3B,D). Autoradiographic studies of the two 18F FPEG
probes (83 and 85) were first performed with sections from Tg
mice. Both ligands showed effective labeling of plaques and
minimal background labeling (Figure 4A,E). The control cases
were clearly void of any notable Aβ labeling (Figure 4B,F). The
same sections were also stained with thioflavin-S, and the
distribution of Aβ plaques perfectly accorded with the results
of autoradiography (Figure 4C,G, red arrows). Autoradiographic
studies of [18F]83 and [18F]85 were then performed with AD
brain sections. As shown in Figure 5A,E, specific labeling of
plaques was observed. Immunohistochemical staining confirmed
the prescence of plaques in the sections (Figure 5B,D,G).
The lipophilicity (log D) of the radiolabeled tracers ([125I]6,
24.34 ( 3.83 26.26 ( 3.57
7.43 ( 1.03
5.67 ( 0.72
5.44 ( 1.45
5.14 ( 0.88
heart
a Expressed as % injected dose per organ.
brain, suggesting them to have more suitable pharmacokinetic
properties for imaging Aβ in AD brains. Because there are no
plaques to cause the retention of Aβ-specific probes, the high
uptake was subsequently followed by a fast washout (0.54, 0.71,
0.90, and 1.27% ID/g at 60 min). The tracer [125I]6 with a N,
N-dimethylamino group showed a lower uptake at 2 min (1.59%
ID/g), indicating low penetration of the intact BBB. Relatively
high lipophilicity was observed for [125I]6 (log D = 3.66 ( 0.09),
and this disparity may account for the lower brain uptake and
high blood uptake. The ratio brain2 min/brain60 min is considered
an important index with which to select tracers with appropriate
kinetics in vivo. The five radiolabeled dibenzylideneacetone
probes showed brain2 min/brain60 min ratios of 5.68, 8.44, 6.59,
4.59, and 4.06 for [125I]6, [125I]70, [125I]71, [18F]83, and
[18F]85, respectively. As compared with [18F]AV-45 (3.90),
the two 18F FPEG probes [18F]83 and [18F]85 had superior
brain2 min/brain60 min ratios. Accordingly, they may have better
signal-to-noise ratios and therefore may be better for detecting
Aβ plaques. Additionally, the thyroid uptake of the three radio-
iodinated probes ([125I]6, [125I]70, and [125I]71) reached
14ꢀ24% ID/g at 1 h postinjection, which indicated deiodination
in vivo. The defluorination, as reflected by bone uptake, for the
two radiofluorinated probes ([18F]83 and [18F]85) was low
(2.33 and 2.54% ID/g at 1 h). As can be expected from the
relatively high log D values, these radiolabeled tracers were
cleared from plasma predominantly by the hepatobiliary system
(ranging from 14.1 to 24.6% ID/g in liver and at 30 min pi). The
hepatobiliar excretion to the intestines was also rather fast, and
radioactivity was observed to accumulate within the intestine at
later time points (ranging from 17.6 to 26.3% ID/g at 60 min pi).
Also, a moderate uptake of these tracers was observed in the
[
125I]70, [125I]71, [18F]83, and [18F]85) measured under
experimental conditions showed relatively high partition coeffi-
cients (log D = 2.97ꢀ3.66), a reflection of the lipophilic proper-
ties of these probes. Biodistribution experiments were performed
in normal mice with these radiolabeled tracers. As shown in
Tables 2 and 3, [125I]70 [125I]71, [18F]83, and [18F]85, but not
[
125I]6, exhibited good initial penetration of the BBB with
excellent initial uptake in the brain (4.56, 4.68, 4.13, and 5.15%
ID/g at 2 min, respectively). As compared with a previously
reported radiofluorinated curcumin (0.52% ID/g at 2 min), these
dibenzylideneacetones showed greatly improved uptake into the
2231
dx.doi.org/10.1021/jm101404k |J. Med. Chem. 2011, 54, 2225–2240

Journal of Medicinal Chemistry
ARTICLE
kidneys, indicating that they too were excreted via the renal
system.
(E)-4-(4-(Dimethylamino)phenyl)but-3-en-2-one (1). To a solution
of 4-(dimethylamino)benzaldehyde (14.92 g, 100 mmol) in 300 mL of
acetone was added 10 mL of NaOH (1 M), and the reaction mixture was
stirred for 12 h at room temperature. The solvent was concentrated to
100 mL, 300 mL of water was added, and the yellow crystal that formed
was collected by filtration, washed with water and cold hexane, and then
dried under vacuum to obtain 13.70 g of 1 (72.5%). 1H NMR (400 MHz,
CDCL3): δ 7.46 (d, J = 16.1 Hz, 1H), 7.44 (d, J = 9.0 Hz, 2H), 6.68 (d,
J = 8.9 Hz, 2H), 6.55 (d, J = 16.1 Hz, 1H), 3.03 (s, 6H), 2.34 (s, 3H). MS
(ESI): m/z calcd for C12H15NO, 189.12; found, 190.10 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-phenylpenta-1,4-dien-3-one
(2). Compound 2 was prepared following general procedure A. Yield,
31.6%. 1H NMR (400 MHz, CDCL3): δ 7.73 (d, J = 15.8 Hz, 1H), 7.71
(d, J = 15.9 Hz, 1H), 7.62 (dd, J = 7.5, 2.0 Hz, 2H), 7.53 (d, J = 8.9 Hz,
2H), 7.45ꢀ7.33 (m, 3H), 7.10 (d, J = 15.9 Hz, 1H), 6.89 (d, J = 15.8 Hz,
1H), 6.70 (d, J = 8.9 Hz, 2H), 3.05 (s, 6H). MS (ESI): m/z calcd for
C19H19NO 277.15; found 278.15 (M þ Hþ).
’ CONCLUSIONS
In conclusion, a new series of novel dibenzylideneacetone
derivatives, containing various substituents, were successfully
prepared as a new backbone structure for Aβ imaging agents.
Most of them displayed excellent affinity for Aβ aggregates (Ki in
the nM range). The SAR study described above indicated that the
introduction of a substituted group at the ortho position reduced
or abolished the binding. However, the para position was highly
tolerant of steric bulk substitutions, which opens up the possi-
bility of developing new, easily labeled radioligands for imaging
Aβ plaques in vivo. Furthermore, the radiolabeled probes
showed good penetration and fast washout in the mouse brain.
A specific plaque-labeling signal was clearly demonstrated for
these probes in Tg mouse brain sections as well as postmortem
AD brain sections. Taken together, the present results suggest
that these novel dibenzylideneacetones may be useful probes for
the diagnosis of AD. Additional chemical modifications of the
dibenzylideneacetone structure may lead to more useful Aβ
imaging agents for both PET and SPECT.
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(4-fluorophenyl)penta-1,4-
dien-3-one (3). Compound 3 was prepared following general procedure
A. Yield, 77.3%. 1H NMR (400 MHz, CDCL3): δ 7.74 (d, J = 15.8 Hz,
1H), 7.69 (d, J = 15.9 Hz, 1H), 7.62 (dd, J = 8.7, 5.4 Hz, 2H), 7.54 (d, J =
8.9 Hz, 2H), 7.11(t, J = 8.6Hz, 2H), 7.04(d, J = 15.9Hz, 1H), 6.88 (d, J =
15.7 Hz, 1H), 6.72 (d, J = 8.9 Hz, 2H), 3.06 (s, 6H). MS (ESI): m/z calcd
for C19H18FNO 295.14; found 296.15 (M þ Hþ).
(1E,4E)-1-(4-Chlorophenyl)-5-(4-(dimethylamino)phenyl)penta-1,
4-dien-3-one (4). Compound 4 was prepared following general proce-
dure A. Yield, 78.5%. 1H NMR (400 MHz, CDCL3): δ 7.72 (d, J = 15.7
Hz, 1H), 7.65 (d, J = 15.9 Hz, 1H), 7.54 (d, J = 8.2 Hz, 2H), 7.52 (d, J =
8.6 Hz, 2H), 7.37 (d, J = 8.5 Hz, 2H), 7.06 (d, J = 15.9 Hz, 1H), 6.85 (d, J
= 15.8 Hz, 1H), 6.69 (d, J = 8.9 Hz, 2H), 3.05 (s, 6H). MS (ESI): m/z
calcd for C19H18ClNO, 311.11; found, 312.10 (M þ Hþ).
’ EXPERIMENTAL SECTION
All of the chemicals used were commercial products employed
1
without further purification. The H NMR spectra were obtained at
400 MHz on Jeol JNM-AL400 NMR spectrometers in CDCl3 solutions
at room temperature with TMS as an internal standard. Chemical shifts
are reported as δ values relative to the internal TMS. Coupling constants
are reported in Hertz. Multiplicity is defined by s (singlet), d (doublet), t
(triplet), and m (multiplet). Mass spectra were acquired with a
Shimadzu GC-MS-QP2010 Plus (ESI). HPLC was performed with a
Shimadzu system (a LC-20AT pump with a SPD-20A UV detector, λ =
254 nm) using a column of Cosmosil C18 (Nakalai Tesque, 5C18-AR-II,
4.6 mm ꢁ 150 mm or 10 mm ꢁ 150 mm) and acetonitrile/water as the
mobile phase. Fluorescence was observed with a Nikon Eclipse 80i
microscope equipped with a BV-2A filter set (excitation, 400ꢀ440 nm;
diachronic mirror, 455 nm; and long pass filter, 470 nm). The purity of
the synthesized compounds was determined using analytical HPLC and
was found to be more than 95%.
Chemistry. General Procedure A: Preparation of Compounds
2ꢀ9, 12ꢀ22, 26ꢀ29, and 32ꢀ48. To a solution of 1 (1ꢀ2 mmol)
and substitued aromatic aldehydes (1ꢀ2 mmol) in 20 mL of ethanol was
added 0.2 mL of NaOMe (28% in methanol). The reaction mixture was
stirred for 12 h at room temperature. The precipitate was collected by
filtration, washed with water and hexane, and recrystallized from ethanol
or purified by silica gel chromatography to afford the final products.
General Procedure B: Preparation of Compounds 10, 23, and 30. A
mixture of nitro compounds (1ꢀ2 mmol) and SnCl2 (2ꢀ4 mmol)
dissolved in 20 mL of ethanol containing 4 mL of concentrated
hydrochloric acid was stirred under reflux for 2 h. After the mixture
had cooled to room temperature, 2 M NaOH (50 mL) was added and
extracted with ethyl acetate (100 mL). The organic layer was dried over
Na2SO4. The solvent was removed, and the residue was purified by silica
gel chromatography to afford the final products.
(1E,4E)-1-(4-Bromophenyl)-5-(4-(dimethylamino)phenyl)penta-1,
4-dien-3-one (5). Compound 5 was prepared following general proce-
1
dure A. Yield, 49.4%. H NMR (400 MHz, CDCL3): δ 7.72 (d, J =
15.7 Hz, 1H), 7.63 (d, J = 15.9 Hz, 1H), 7.55ꢀ7.50 (m, 4H), 7.47 (d, J =
8.5 Hz, 2H), 7.08 (d, J = 15.8 Hz, 1H), 6.86 (d, J = 15.7 Hz, 1H), 6.70 (d,
J = 8.8 Hz, 2H), 3.05 (s, 6H). MS (ESI): m/z calcd for C19H18BrNO,
355.06; found, 356.05 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(4-iodophenyl)penta-1,
4-dien-3-one (6). Compound 6 was prepared following general proce-
dure A. Yield, 61.5%. 1H NMR (400 MHz, CDCL3): δ 7.76 (d, J = 8.4
Hz, 2H), 7.74 (d, J = 15.8 Hz, 1H), 7.63 (d, J = 15.8 Hz, 1H), 7.54 (d, J =
8.9 Hz, 2H), 7.35 (d, J = 8.5 Hz, 2H), 7.11 (d, J = 15.9 Hz, 1H), 6.88 (d,
J = 15.7 Hz, 1H), 6.72 (d, J = 8.9 Hz, 2H), 3.07 (s, 6H). HRMS (EI): m/z
(EIþ): calcd for C19H18INO, 403.0433; found, 403.0426 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(4-hydroxyphenyl)penta-1,
4-dien-3-one (7). Compound 7 was prepared following general proce-
dure A. Yield, 19.5%. 1H NMR (400 MHz, CD3OD): δ 7.72 (d, J = 16.3
Hz, 1H), 7.67 (d, J = 16.4 Hz, 1H), 7.56 (d, J = 8.8 Hz, 4H), 7.05 (d, J =
15.8 Hz, 1H), 6.97 (d, J = 15.7 Hz, 1H), 6.83 (d, J = 8.6 Hz, 2H), 6.76 (d,
J = 9.0 Hz, 2H), 3.03 (s, 6H). MS (ESI): m/z calcd for C19H19NO2,
293.14; found, 294.20 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(4-methoxyphenyl)penta-
1,4-dien-3-one (8). Compound 8 was prepared following general
1
procedure A. Yield, 71.3%. H NMR (400 MHz, CDCL3): δ 7.73 (d,
J = 15.8 Hz, 1H), 7.70 (d, J = 15.8 Hz, 1H), 7.59 (d, J = 8.8 Hz, 2H), 7.53
(d, J = 8.9 Hz, 2H), 6.99 (d, J = 15.8 Hz, 1H), 6.95 (d, J = 8.8 Hz, 2H),
6.89 (d, J = 15.7 Hz, 1H), 6.71 (d, J = 8.9 Hz, 2H), 3.87 (s, 3H), 3.05
(s, 6H). MS (ESI): m/z calcd for C20H21NO2, 307.16; found, 308.15
(M þ Hþ).
General Procedure C: Preparation of Compounds 11, 24, 25, and
31. To a solution of amino compounds (1ꢀ2 mmol) and K2CO3 (1ꢀ2
mmol) in 20 mL of acetone was added CH3I (2ꢀ4 mmol) dropwise, and
the reaction mixture was stirred for 8 h at room temperature. After
evaporation, the solvent was removed, and the residue was purified by
silica gel chromatography to afford the final products.
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(4-nitrophenyl)penta-1,4-
dien-3-one (9). Compound 9 was prepared following general procedure
A. Yield, 64.3%. 1H NMR (400 MHz, CDCL3): δ 8.28 (d, J = 8.8 Hz, 2H),
7.77 (d, J = 14.9 Hz, 1H), 7.77 (d, J = 9.0 Hz, 2H), 7.73 (d, J = 15.2 Hz,
2232
dx.doi.org/10.1021/jm101404k |J. Med. Chem. 2011, 54, 2225–2240

Journal of Medicinal Chemistry
ARTICLE
1H), 7.55 (d, J = 8.9 Hz, 2H), 7.22 (d, J = 15.8 Hz, 1H), 6.88 (d, J = 15.8
Hz, 1H), 6.72 (d, J = 8.9 Hz, 2H), 3.08 (s, 6H). MS (ESI): m/z calcd for
C19H18N2O3, 322.13; found, 323.10 (M þ Hþ).
(d, J = 15.7 Hz, 1H), 6.87 (d, J = 15.8 Hz, 1H), 6.70 (d, J = 8.9 Hz, 2H),
5.11 (s, 2H), 3.04 (s, 6H). MS (ESI): m/z calcd for C26H25NO2, 383.19;
found, 384.25 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(3-fluorophenyl)penta-1,4-
dien-3-one (19). Compound 19 was prepared following general proce-
dure A. Yield, 63.4%. 1H NMR (400 MHz, CDCL3): δ 7.87 (d, J = 15.8
Hz, 1H), 7.79 (d, J = 15.8 Hz, 1H), 7.67 (d, J = 8.9 Hz, 2H), 7.51 (ddd, J =
5.4, 3.7, 1.7 Hz, 2H), 7.45 (dd, J = 10.2, 3.0 Hz, 1H), 7.22 (d, J = 15.8 Hz,
1H), 7.00 (d, J = 15.7 Hz, 1H), 6.84 (d, J = 8.9 Hz, 2H), 3.19 (s, 6H). MS
(ESI): m/z calcd for C19H18FNO, 295.14; found, 296.10 (M þ Hþ).
(1E,4E)-1-(3-Bromophenyl)-5-(4-(dimethylamino)phenyl)penta-
1,4-dien-3-one (20). Compound 20 was prepared following general
procedure A. Yield, 77.5%. 1H NMR (400 MHz, CDCL3): δ 7.79 (t, J =
1.7 Hz, 1H), 7.75 (d, J = 15.8 Hz, 1H), 7.64 (d, J = 15.8 Hz, 1H),
7.58ꢀ7.50 (m, 4H), 7.30 (t, J = 7.9 Hz, 1H), 7.11 (d, J = 15.8 Hz, 1H),
6.88 (d, J = 15.7 Hz, 1H), 6.72 (d, J = 8.9 Hz, 2H), 3.08 (s, 6H). MS
(ESI): m/z calcd for C19H18BrNO, 355.06; found, 356.05 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(3-iodophenyl)penta-1,4-
dien-3-one (21). Compound 21 was prepared following general proce-
dure A. Yield, 57.3%. 1H NMR (400 MHz, CDCL3): δ 7.98(s, 1H), 7.73
(d, J = 15.6 Hz, 1H), 7.71 (d, J = 7.6 Hz, 1H), 7.61ꢀ7.52 (m, 4H), 7.15
(t, J = 7.6 Hz, 1H), 7.08 (d, J = 16.0 Hz, 1H), 6.86 (d, J = 15.6 Hz, 1H),
6.71 (d, J = 9.2 Hz, 2H), 3.06 (s, 6H). MS (ESI): m/z calcd for
C19H18INO, 403.04; found, 404.05 (M þ Hþ).
(1E,4E)-1-(4-Aminophenyl)-5-(4-(dimethylamino)phenyl)penta-1,
4-dien-3-one (10). Compound 10 was prepared following general
procedure B. Yield, 11.5%. 1H NMR (400 MHz, CDCL3): δ 7.71 (d, J =
15.1 Hz, 1H), 7.67 (d, J = 15.1 Hz, 1H), 7.53 (d, J = 8.8 Hz, 2H), 7.47 (d,
J = 8.4 Hz, 2H), 6.93 (d, J = 15.8 Hz, 1H), 6.89 (d, J = 15.7 Hz, 1H), 6.72
(d, J = 8.5 Hz, 2H), 6.69 (d, J = 8.2 Hz, 2H), 3.98 (s, 2H), 3.06 (s, 6H).
MS (ESI): m/z calcd for C19H20N2O, 292.16; found, 293.15 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(4-(methylamino)phenyl)
penta-1,4-dien-3-one (11). Compound 11 was prepared following
1
general procedure C. Yield, 6.2%. H NMR (400 MHz, CDCL3): δ
7.68 (d, J = 16.3 Hz, 1H), 7.67 (d, J = 15.7 Hz, 1H), 7.51 (d, J = 8.9 Hz,
2H), 7.48 (d, J = 8.6 Hz, 2H), 6.88 (d, J = 15.7 Hz, 1H), 6.88 (d, J = 15.7
Hz, 1H), 6.69 (d, J = 8.9 Hz, 2H), 6.59 (d, J = 8.6 Hz, 2H), 3.04 (s, 6H),
2.89 (s, 3H). MS (ESI): m/z calcd for C20H22N2O, 306.176; found,
307.20 (M þ Hþ).
(1E,4E)-1,5-Bis(4-(dimethylamino)phenyl)penta-1,4-dien-3-one
(12). Compound 12 was prepared following general procedure A. Yield,
32.2%. 1H NMR (400 MHz, CDCL3): δ 7.71 (d, J = 15.7 Hz, 2H), 7.54
(d, J = 8.9 Hz, 4H), 6.91 (d, J = 15.7 Hz, 2H), 6.72 (d, J = 8.9 Hz, 4H),
3.06 (s, 12H). MS (ESI): m/z calcd for C21H24N2O, 320.19; found,
321.20 (M þ Hþ).
4-((1E,4E)-5-(4-(Dimethylamino)phenyl)-3-oxopenta-1,4-dien-1-yl)-
benzoic Acid (13). Compound 13 was prepared following general
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(3-nitrophenyl)penta-1,4-
dien-3-one (22). Compound 22 was prepared following general proce-
dure A. Yield, 39.4%. 1H NMR (400 MHz, CDCL3): δ 8.49 (s, 1H), 8.23
(dd, J = 8.2, 2.2 Hz, 1H), 7.88 (d, J = 7.8 Hz, 1H), 7.76 (d, J = 15.2 Hz,
1H), 7.72 (d, J = 14.8 Hz, 1H), 7.59 (t, J = 8.0 Hz, 1H), 7.54 (d, J = 8.6
Hz, 2H), 7.22 (d, J = 15.9 Hz, 1H), 6.87 (d, J = 15.8 Hz, 1H), 6.71 (d, J =
8.8 Hz, 2H), 3.06 (s, 6H). MS (ESI): m/z calcd for C19H18N2O3,
322.13; found, 323.15 (M þ Hþ).
1
procedure A. Yield, 2.5%. H NMR (400 MHz, CDCL3): δ 8.14 (d,
J = 8.3 Hz, 2H), 7.75 (d, J = 15.8 Hz, 1H), 7.73 (d, J = 15.6 Hz, 1H), 7.71
(d, J = 8.1 Hz, 2H), 7.54 (d, J = 8.8 Hz, 2H), 7.20 (d, J = 15.9 Hz, 1H),
6.88 (d, J = 15.7 Hz, 1H), 6.71 (d, J = 8.8 Hz, 2H), 3.06 (s, 6H). MS
(ESI): m/z calcd for C20H19NO3, 321.14; found, 322.10 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(4-(trifluoromethyl)phenyl)
penta-1,4-dien-3-one (14). Compound 14 was prepared following
(1E,4E)-1-(3-Aminophenyl)-5-(4-(dimethylamino)phenyl)penta-1,
4-dien-3-one (23). Compound 23 was prepared following general
1
general procedure A. Yield, 79.9%. H NMR (400 MHz, CDCL3): δ
1
7.76 (d, J = 15.9 Hz, 1H), 7.75ꢀ7.66 (m, 5H), 7.55 (d, J = 8.8 Hz, 2H),
7.17 (d, J = 15.9 Hz, 1H), 6.89 (d, J = 15.7 Hz, 1H), 6.72 (d, J = 8.9 Hz,
2H), 3.08 (s, 6H). MS (ESI): m/z calcd for C20H18F3NO, 345.13; found,
346.15 (M þ Hþ).
procedure B. Yield, 40.9%. H NMR (400 MHz, CDCL3): δ 7.71 (d,
J = 15.7 Hz, 1H), 7.62 (d, J = 15.9 Hz, 1H), 7.52 (d, J = 8.9 Hz, 2H), 7.19
(t, J = 7.8 Hz, 1H), 7.04 (d, J = 2.3 Hz, 1H), 7.03 (d, J = 15.9 Hz, 1H),
6.92 (d, J = 1.8 Hz, 1H), 6.87 (d, J = 15.7 Hz, 1H), 6.71 (dd, J = 9.9, 2.3
Hz, 1H), 6.70 (d, J = 8.9 Hz, 2H), 3.74 (s, 2H), 3.05 (s, 6H). MS (ESI):
m/z calcd for C19H20N2O, 292.16; found, 293.10 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(p-tolyl)penta-1,4-dien-3-
one (15). Compound 15 was prepared following general procedure A.
Yield, 84.5%. 1H NMR (400 MHz, CDCL3): δ 7.74 (d, J = 15.8 Hz, 1H),
7.72 (d, J = 15.9 Hz, 1H), 7.55 (d, J = 8.9 Hz, 2H), 7.54 (d, J = 8.0 Hz,
2H), 7.24 (d, J = 8.0 Hz, 2H), 7.08 (d, J = 15.9 Hz, 1H), 6.91 (d, J = 15.7
Hz, 1H), 6.72 (d, J = 8.9 Hz, 2H), 3.07 (s, 6H), 2.41 (s, 3H). MS (ESI):
m/z calcd for C21H20NO, 291.16; found, 292.00 (M þ Hþ).
(1E,4E)-1-(4-(Diethylamino)phenyl)-5-(4-(dimethylamino)phenyl)
penta-1,4-dien-3-one (16). Compound 16 was prepared following
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(3-(methylamino)phenyl)
penta-1,4-dien-3-one (24). Compound 24 was prepared following
1
general procedure C. Yield, 30.0%. H NMR (400 MHz, CDCL3): δ
7.73 (d, J = 15.7 Hz, 1H), 7.67 (d, J = 15.8 Hz, 1H), 7.54 (d, J = 8.9 Hz,
2H), 7.24 (t, J = 7.8 Hz, 1H), 7.06 (d, J = 15.9 Hz, 1H), 7.01 (d, J = 7.6
Hz, 1H), 6.92 (d, J = 15.8 Hz, 1H), 6.84 (s, 1H), 6.72 (d, J = 8.9 Hz, 2H),
6.67 (d, J = 8.0 Hz, 1H), 3.07 (s, 6H), 2.90 (s, 3H). MS (ESI): m/z calcd
for C20H22N2O, 306.17; found, 307.15 (M þ Hþ).
1
general procedure A. Yield, 46.2%. H NMR (400 MHz, CDCL3): δ
7.47 (d, J = 15.9 Hz, 2H), 7.44 (d, J = 8.9 Hz, 4H), 6.68 (d, J = 8.8 Hz,
4H), 6.55 (d, J = 16.1 Hz, 2H), 3.03 (s, 12H), 2.34 (s, 6H). MS (ESI):
m/z calcd for C23H28N2O, 348.22; found, 349.20 (M þ Hþ).
(1E,4E)-1-(3-(Dimethylamino)phenyl)-5-(4-(dimethylamino)phenyl)
penta-1,4-dien-3-one (25). Compound 25 was prepared following
1
general procedure C. Yield, 28.4%. H NMR (400 MHz, CDCL3): δ
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(4-(diphenylamino)phenyl)
penta-1,4-dien-3-one (17). Compound 17 was prepared following gen-
eralprocedure A. Yield, 41.7%. 1H NMR (400 MHz, CDCL3): δ 7.70 (d, J
= 15.4 Hz, 1H), 7.66 (d, J = 15.5Hz, 1H), 7.52 (d, J = 8.8 Hz, 2H), 7.46 (d,
J = 8.7 Hz, 2H), 7.30 (t, J = 7.9 Hz, 4H), 7.14 (dd, J = 7.7, 0.9 Hz, 4H), 7.09
(td, J = 7.5, 1.0 Hz, 2H), 7.02 (d, J = 8.6 Hz, 2H), 6.95 (d, J = 15.8 Hz, 1H),
6.87 (d, J = 15.7 Hz, 1H), 6.69 (d, J = 8.8 Hz, 2H), 3.04 (s, 6H). MS (ESI):
m/z calcd for C31H28N2O, 444.22; found, 445.15 (M þ Hþ).
7.72 (d, J = 15.7 Hz, 1H), 7.68 (d, J = 15.8 Hz, 1H), 7.53 (d, J = 8.7 Hz,
2H), 7.27 (t, J = 7.7 Hz, 1H), 7.05 (dd, J = 15.9, 0.7 Hz, 1H), 7.01 (d, J =
7.3 Hz, 1H), 6.93 (s, 1H), 6.91 (dd, J = 15.7, 0.8 Hz, 1H), 6.78 (dd, J = 8.1,
2.4 Hz, 1H), 6.70 (d, J = 8.6 Hz, 2H), 3.04 (s, 6H), 2.99 (s, 6H). MS
(ESI): m/z calcd for C21H24N2O, 320.19; found, 321.10 (M þ Hþ).
(1E,4E)-1-(2-(Benzyloxy)phenyl)-5-(4-(dimethylamino)phenyl)penta
-1,4-dien-3-one (26). Compound 26 was prepared following general
procedure A. Yield, 51.0%. 1H NMR (400 MHz, CDCL3): δ 8.06 (d, J =
16.1 Hz, 1H), 7.62 (d, J = 7.4 Hz, 1H), 7.61 (d, J = 15.8 Hz, 2H),
7.53ꢀ7.28 (m, 10H), 7.23 (d, J = 16.1 Hz, 1H), 7.00 (t, J = 8.1 Hz, 2H),
6.85 (d, J = 15.8 Hz, 1H), 6.68 (d, J = 8.8 Hz, 2H), 5.19 (s, 2H), 3.04
(s, 8H). MS (ESI): m/z calcd for C26H25NO2, 383.19; found, 384.15
(M þ Hþ).
(1E,4E)-1-(4-(Benzyloxy)phenyl)-5-(4-(dimethylamino)phenyl)penta
-1,4-dien-3-one (18). Compound 18 was prepared following general
procedure A. Yield, 27.4%. 1H NMR (400 MHz, CDCL3): δ 7.70 (d, J =
15.8 Hz, 1H), 7.68 (d, J = 15.7 Hz, 1H), 7.57 (d, J = 8.7 Hz, 2H), 7.52
(d, J = 8.9 Hz, 2H), 7.47ꢀ7.31 (m, 5H), 7.00 (d, J = 8.8 Hz, 2H), 6.97
2233
dx.doi.org/10.1021/jm101404k |J. Med. Chem. 2011, 54, 2225–2240

Journal of Medicinal Chemistry
ARTICLE
(1E,4E)-1-(2-Chlorophenyl)-5-(4-(dimethylamino)phenyl)penta-1,
4-dien-3-one (27). Compound 27 was prepared following general
procedure A. Yield, 78.5%. H NMR (400 MHz, CDCL3): δ 7.72 (d,
Hz, 2H), 3.97 (s, 3H), 3.95 (s, 3H), 3.06 (s, 6H). MS (ESI): m/z calcd
for C21H23NO3, 337.17; found, 338.15 (M þ Hþ).
1
(1E,4E)-1-(3,5-Dimethoxyphenyl)-5-(4-(dimethylamino)phenyl)penta
-1,4-dien-3-one (36). Compound 36 was prepared following general
procedure A. Yield, 70.4%. 1H NMR (400 MHz, CDCL3): δ 7.72 (d, J =
15.7 Hz, 1H), 7.62 (d, J = 15.8 Hz, 1H), 7.53 (d, J = 8.9 Hz, 2H), 7.05 (d,
J = 15.8 Hz, 1H), 6.89 (d, J = 15.8 Hz, 1H), 6.76 (s, 2H), 6.70 (d, J = 8.9
Hz, 2H), 6.51 (s, 1H), 3.84 (s, 6H), 3.05 (s, 6H). MS (ESI): m/z calcd
for C21H23NO3, 337.17; found, 338.15 (M þ Hþ).
J = 15.7 Hz, 1H), 7.62 (d, J = 16.0 Hz, 2H), 7.60 (s, 1H), 7.52 (d, J = 8.9
Hz, 2H), 7.48ꢀ7.45 (m, 1H), 7.39ꢀ7.32 (m, 2H), 7.09 (d, J = 15.8 Hz,
1H), 6.85 (d, J = 15.8 Hz, 1H), 6.70 (d, J = 8.9 Hz, 2H), 3.05 (s, 6H). MS
(ESI): m/z calcd for C19H18ClNO, 311.11; found, 312.15 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(2-hydroxyphenyl)penta-
1,4-dien-3-one (28). Compound 28 was prepared following general
procedure A. Yield, 37.2%. 1H NMR (400 MHz, CDCL3): δ 8.09 (d, J =
16.1 Hz, 1H), 7.76 (d, J = 15.7 Hz, 1H), 7.59 (d, J = 7.6 Hz, 1H), 7.55 (d,
J = 8.8 Hz, 2H), 7.33ꢀ7.21 (m, 2H), 7.00ꢀ6.90 (m, 3H), 6.71 (d, J = 8.8
Hz, 2H), 3.06 (s, 6H). MS (ESI): m/z calcd for C19H19NO2, 293.14;
found, 294.00 (M þ Hþ).
(1E,4E)-1-(2,4-Dimethoxyphenyl)-5-(4-(dimethylamino)phenyl)
penta-1,4-dien-3-one (37). Compound 37 was prepared following
1
general procedure A. Yield, 71.4%. H NMR (400 MHz, CDCL3): δ
7.97 (d, J = 16.1 Hz, 1H), 7.69 (d, J = 15.7 Hz, 1H), 7.55 (d, J = 8.6 Hz,
1H), 7.52 (d, J = 8.9 Hz, 2H), 7.05 (d, J = 16.0 Hz, 1H), 6.92 (d, J = 15.7
Hz, 1H), 6.69 (d, J = 8.9 Hz, 2H), 6.53 (dd, J = 8.6, 2.4 Hz, 1H), 6.47 (d,
J = 2.3 Hz, 1H), 3.90 (s, 3H), 3.85 (s, 3H), 3.03 (s, 6H). MS (ESI): m/z
calcd for C21H23NO3, 337.17; found, 338.10 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(2-nitrophenyl)penta-1,4-
dien-3-one (29). Compound 29 was prepared following general proce-
dure A. Yield, 35.8%. 1H NMR (400 MHz, CDCL3): δ 8.07 (d, J = 15.9
Hz, 1H), 8.05 (dd, J = 8.1, 1.2 Hz, 1H), 7.75 (d, J = 15.8 Hz, 1H), 7.73
(dd, J = 7.7, 1.5 Hz, 1H), 7.66 (td, J = 7.8, 1.3 Hz, 1H), 7.55 (d, J = 7.7 Hz,
1H), 7.53 (d, J = 8.9 Hz, 2H), 6.93 (d, J = 15.9 Hz, 1H), 6.92 (d, J = 15.7
Hz, 1H), 6.70 (d, J = 8.9 Hz, 2H), 3.05 (s, 6H). MS (ESI): m/z calcd for
C19H18N2O3, 322.13; found, 323.15 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(3,4,5-trimethoxyphenyl)
penta-1,4-dien-3-one (38). Compound 38 was prepared following
1
general procedure A. Yield, 71.6%. H NMR (400 MHz, CDCL3): δ
7.73 (d, J = 15.7 Hz, 1H), 7.63 (d, J = 15.8 Hz, 1H), 7.53 (d, J = 8.7 Hz,
2H), 6.97 (d, J = 15.8 Hz, 1H), 6.90 (d, J = 15.7 Hz, 1H), 6.84 (s, 2H),
6.69 (d, J = 8.7 Hz, 2H), 3.92 (s, 6H), 3.90 (s, 3H), 3.05 (s, 6H). MS
(ESI): m/z calcd for C22H25NO4, 367.18; found, 368.05 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(2,4,6-trimethoxyphenyl)-
penta-1,4-dien-3-one (39). Compound 39 was prepared following
(1E,4E)-1-(2-Aminophenyl)-5-(4-(dimethylamino)phenyl)penta-1,
4-dien-3-one (30). Compound 30 was prepared following general
1
procedure B. Yield, 41.4%. H NMR (400 MHz, CDCL3): δ 8.09 (d,
J = 15.4 Hz, 1H), 8.07 (d, J = 15.6 Hz, 1H), 7.78 (d, J = 8.1 Hz, 1H), 7.70
(ddd, J = 8.4, 6.9, 1.5 Hz, 1H), 7.67 (d, J = 8.6 Hz, 1H), 7.64 (d, J = 16.3
Hz, 1H), 7.57 (d, J = 8.9 Hz, 2H), 7.48 (ddd, J = 8.0, 6.9, 1.1 Hz, 1H),
7.25 (d, J = 16.3 Hz, 1H), 6.76 (d, J = 8.9 Hz, 2H), 3.04 (s, 6H). MS
(ESI): m/z calcd for C19H20N2O, 292.16; found, 293.00 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(2-(methylamino)phenyl)
penta-1,4-dien-3-one (31). Compound 31 was prepared following
1
general procedure A. Yield, 58.8%. H NMR (400 MHz, CDCL3): δ
8.14 (d, J = 16.1 Hz, 1H), 7.67 (d, J = 15.7 Hz, 1H), 7.52 (d, J = 8.9 Hz,
2H), 7.41 (d, J = 16.1 Hz, 1H), 6.93 (d, J = 15.7 Hz, 1H), 6.69 (d, J = 8.9
Hz, 2H), 6.14 (s, 2H), 3.90 (s, 6H), 3.86 (s, 3H), 3.03 (s, 6H). MS (ESI):
m/z calcd for C22H25NO4, 367.18; found, 368.05 (M þ Hþ).
(1E,4E)-1-(4-(Benzyloxy)-3-methoxyphenyl)-5-(4-(dimethylamino)
phenyl)penta-1,4-dien-3-one (40). Compound 40 was prepared fol-
lowing general procedure A. Yield, 61.6%. 1H NMR (400 MHz,
CDCL3): δ 7.71 (d, J = 15.7 Hz, 1H), 7.65 (d, J = 15.8 Hz, 1H), 7.52
(d, J = 8.9 Hz, 2H), 7.45 (d, J = 8.4 Hz, 2H), 7.42ꢀ7.35 (m, 2H), 7.32 (d,
J = 7.1 Hz, 1H), 7.16 (d, J = 1.9 Hz, 1H), 7.13 (dd, J = 8.3, 2.0 Hz, 1H),
6.94 (d, J = 15.8 Hz, 1H), 6.90 (d, J = 8.7 Hz, 1H), 6.89 (d, J = 15.6
Hz, 1H), 6.69 (d, J = 8.9 Hz, 2H), 5.21 (s, 2H), 3.95 (s, 3H), 3.04
(s, 6H). MS (ESI): m/z calcd for C27H27NO3, 413.20; found, 414.20
(M þ Hþ).
1
general procedure C. Yield, 82.4%. H NMR (400 MHz, CDCL3): δ
8.35 (d, J = 8.8 Hz, 1H), 8.03 (d, J = 8.4 Hz, 1H), 8.00ꢀ7.92 (m, 6H),
7.84 (d, J = 16.2 Hz, 1H), 7.78 (t, J = 7.2 Hz, 1H), 7.59 (d, J = 16.2 Hz,
1H), 7.56 (d, J = 16.4 Hz, 1H), 3.72 (s, 9H). MS (ESI): m/z calcd for
C20H22N2O, 306.17; found, 307.10 (M þ Hþ).
(1E,4E)-1-(2,6-Dichlorophenyl)-5-(4-(dimethylamino)phenyl)penta-1,
4-dien-3-one (32). Compound 32 was prepared following general
1
procedure A. Yield, 6.3%. H NMR (400 MHz, CDCL3): δ 7.77 (d,
J = 16.2 Hz, 1H), 7.74 (d, J = 15.8 Hz, 1H), 7.54 (d, J = 8.9 Hz, 2H), 7.40
(d, J = 8.1 Hz, 2H), 7.25 (d, J = 16.2 Hz, 1H), 7.21 (t, J = 8.0 Hz, 1H),
6.88 (d, J = 15.8 Hz, 1H), 6.72 (d, J = 8.9 Hz, 2H), 3.07 (s, 6H). MS
(ESI): m/z calcd for C19H17Cl2NO, 345.07; found, 346.95 (M þ Hþ).
(1E,4E)-1-(2-Chloro-6-fluorophenyl)-5-(4-(dimethylamino)phenyl)
penta-1,4-dien-3-one (33). Compound 33 was prepared following
(1E,4E)-1-(4-Bromo-2-hydroxyphenyl)-5-(4-(dimethylamino)phenyl)
penta-1,4-dien-3-one (41). Compound 41 was prepared following
1
general procedure A. Yield, 15.0%. H NMR (400 MHz, CD3OD): δ
7.93 (d, J = 16.0 Hz, 1H), 7.89 (s, 1H), 7.76 (d, J = 2.7 Hz, 1H), 7.74 (d,
J = 16.4 Hz, 1H), 7.56 (d, J = 8.9 Hz, 2H), 7.32 (dd, J = 9.2, 3.0 Hz, 1H),
7.29 (d, J = 16.0 Hz, 1H), 6.94 (d, J = 15.7 Hz, 1H), 6.80 (d, J = 8.7 Hz,
1H), 6.75 (d, J = 9.0 Hz, 2H), 3.04 (s, 6H). MS (ESI): m/z calcd for
C19H18BrNO2, 371.05; found, 372.00 (M þ Hþ).
1
general procedure A. Yield, 62.5%. H NMR (400 MHz, CDCL3): δ
7.91 (d, J = 16.2 Hz, 1H), 7.75 (d, J = 15.8 Hz, 1H), 7.55 (d, J = 8.9 Hz,
2H), 7.39 (d, J = 16.2 Hz, 1H), 7.35ꢀ7.22 (m, 2H), 7.16ꢀ7.02 (m, 1H),
6.88 (d, J = 15.8 Hz, 1H), 6.72 (d, J = 8.9 Hz, 2H), 3.07 (s, 6H). MS
(ESI): m/z calcd for C19H17ClFNO, 329.10; found, 330.15 (M þ Hþ).
(1E,4E)-1-(3,5-Bis(trifluoromethyl)phenyl)-5-(4-(dimethylamino)
phenyl)penta-1,4-dien-3-one (34). Compound 34 was prepared fol-
lowing general procedure A. Yield, 21.3%. 1H NMR (400 MHz,
CDCL3): δ 8.01 (s, 1H), 7.87 (s, 1H), 7.76 (d, J = 15.8 Hz, 1H), 7.72
(d, J = 15.9 Hz, 1H), 7.54 (d, J = 8.9 Hz, 1H), 7.21 (d, J = 15.8 Hz, 1H),
6.86 (d, J = 15.7 Hz, 1H), 6.70 (d, J = 8.9 Hz, 1H), 3.06 (s, 6H). MS
(ESI): m/z calcd for C21H17F6NO, 413.12; found, 413.85 (M þ Hþ).
(1E,4E)-1-(3,4-Dimethoxyphenyl)-5-(4-(dimethylamino)phenyl)penta
-1,4-dien-3-one (35). Compound 35 was prepared following general
procedure A. Yield, 40.8%. 1H NMR (400 MHz, CDCL3): δ 7.74 (d, J =
15.7 Hz, 1H), 7.69 (d, J = 15.8 Hz, 1H), 7.55 (d, J = 8.9 Hz, 2H), 7.22
(dd, J = 8.3, 1.9 Hz, 1H), 7.17 (d, J = 1.9 Hz, 1H), 6.97 (d, J = 15.8 Hz,
1H), 6.92 (d, J = 15.8 Hz, 1H), 6.91 (d, J = 8.4 Hz, 1H), 6.72 (d, J = 8.9
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(3-phenoxyphenyl)penta-
1,4-dien-3-one (42). Compound 42 was prepared following general
procedure A. Yield, 83.9%. 1H NMR (400 MHz, CDCL3): δ 7.70 (d, J =
15.7 Hz, 1H), 7.64 (d, J = 15.9 Hz, 1H), 7.51 (d, J = 8.8 Hz, 2H),
7.42ꢀ7.31 (m, 4H), 7.25 (s, 1H), 7.15 (t, J = 7.4 Hz, 1H), 7.08ꢀ6.99 (m,
4H), 6.85 (d, J = 15.7 Hz, 1H), 6.69 (d, J = 8.8 Hz, 2H), 3.04 (s, 6H). MS
(ESI): m/z calcd for C25H23NO2, 369.17; found, 370.15 (M þ Hþ).
(1E,4E)-1-(2-(Benzyloxy)-4-nitrophenyl)-5-(4-(dimethylamino)phenyl)
penta-1,4-dien-3-one (43). Compound 43 was prepared following
1
general procedure A. Yield, 83.3%. H NMR (400 MHz, CDCL3): δ
8.54 (d, J = 2.8 Hz, 1H), 8.20 (dd, J = 9.1, 2.8 Hz, 1H), 8.02 (d, J = 16.0
Hz, 1H), 7.67 (d, J = 15.8 Hz, 1H), 7.56ꢀ7.36 (m, 7H), 7.30 (d, J = 15.9
Hz, 1H), 7.05 (d, J = 9.2 Hz, 1H), 6.82 (d, J = 15.7 Hz, 1H), 6.70 (d, J =
8.9 Hz, 2H), 5.30 (s, 2H), 3.06 (s, 6H). MS (ESI): m/z calcd for
C26H24N2O4, 428.17; found, 429.15 (M þ Hþ).
2234
dx.doi.org/10.1021/jm101404k |J. Med. Chem. 2011, 54, 2225–2240

Journal of Medicinal Chemistry
ARTICLE
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(4-(trityloxy)phenyl)penta-
1,4-dien-3-one (44). Compound 44 was prepared following general
procedure A. Yield, 40.6%. 1H NMR (400 MHz, CDCL3): δ 7.65 (d, J =
15.8 Hz, 1H), 7.53 (d, J = 15.8 Hz, 1H), 7.50ꢀ7.41 (m, 8H), 7.33ꢀ7.23
(m, 11H), 6.85 (d, J = 15.8 Hz, 1H), 6.81 (d, J = 15.7 Hz, 1H), 6.71 (d,
J = 8.6 Hz, 2H), 6.68 (d, J = 8.8 Hz, 2H), 3.03 (s, 6H). MS (ESI): m/z
calcd for C38H33NO2, 535.25; found, 536.75 (M þ Hþ).
7.05ꢀ7.02 (m, 2H), 6.79 (d, J = 15.7 Hz, 1H), 6.78 (d, J = 15.5 Hz, 1H),
6.69 (d, J = 8.9 Hz, 2H), 3.05 (s, 6H). MS (ESI): m/z calcd for
C17H16BrNOS, 361.01; found, 362.10 (M þ Hþ).
(1E,4E)-1-(50-Bromo-[2,20-bithiophen]-5-yl)-5-(4-(dimethylamino)-
phenyl)penta-1,4-dien-3-one (53). Compound 53 was prepared fol-
lowing general procedure A. Yield, 72.1%. 1H NMR (400 MHz,
CDCL3): δ 7.76 (d, J = 15.2 Hz, 1H), 7.69 (d, J = 15.6 Hz, 1H), 7.52
(d, J = 8.8 Hz, 2H), 7.20 (d, J = 3.2 Hz, 1H), 7.06 (d, J = 4.0 Hz, 1H), 7.00
(dd, J = 6.8, 4.0 Hz, 2H), 6.84 (d, J = 15.2 Hz, 1H), 6.81 (d, J = 15.6 Hz,
1H), 6.69 (d, J = 9.2 Hz, 2H), 3.05 (s, 6H). MS (ESI): m/z calcd for
C21H18BrNOS2, 443.00; found, 444.25 (M þ Hþ).
(1E,4E)-1-(6-Chloropyridin-3-yl)-5-(4-(dimethylamino)phenyl)penta-
1,4-dien-3-one (45). Compound 45 was prepared following general
procedure A. Yield, 84.7%. 1H NMR (400 MHz, CDCL3): δ 8.59 (d, J =
2.3 Hz, 1H), 7.87 (dd, J = 8.3, 2.5 Hz, 1H), 7.73 (d, J = 15.7 Hz, 1H), 7.63
(d, J = 15.9 Hz, 1H), 7.52 (d, J = 8.9 Hz, 2H), 7.37 (d, J = 8.3 Hz, 1H),
7.12 (d, J = 15.9 Hz, 1H), 6.85 (d, J = 15.7 Hz, 1H), 6.69 (d, J = 8.9 Hz,
2H), 3.05 (s, 6H). MS (ESI): m/z calcd for C18H17ClN2O, 312.10;
found, 313.05 (M þ Hþ).
(1E,4E)-1-(Benzo[d][1,3]dioxol-5-yl)-5-(4-(dimethylamino)phenyl)
penta-1,4-dien-3-one (54). Compound 54 was prepared following
1
general procedure A. Yield, 71.9%. H NMR (400 MHz, CDCL3): δ
7.70 (d, J = 15.8 Hz, 1H), 7.63 (d, J = 15.8 Hz, 1H), 7.52 (d, J = 8.9 Hz,
2H), 7.13 (d, J = 1.6 Hz, 1H), 7.09 (dd, J = 8.0, 1.7 Hz, 1H), 6.93 (d, J =
15.8 Hz, 1H), 6.86 (d, J = 11.6 Hz, 1H), 6.83 (d, J = 3.9 Hz, 1H), 6.69 (d,
J = 8.9 Hz, 2H), 6.02 (s, 2H), 3.04 (s, 6H). MS (ESI): m/z calcd for
C20H19NO3, 321.14; found, 322.15 (M þ Hþ).
(1E,4E)-1-(6-Bromopyridin-3-yl)-5-(4-(dimethylamino)phenyl)penta-
1,4-dien-3-one (46). Compound 46 was prepared following general
procedure A. Yield, 67.7%. 1H NMR (400 MHz, CDCL3): δ 8.57 (d, J =
2.5 Hz, 1H), 7.76 (dd, J = 8.1, 2.5 Hz, 1H), 7.74 (d, J = 15.6 Hz, 1H), 7.61
(d, J = 15.9 Hz, 1H), 7.53 (dd, J = 8.6, 1.9 Hz, 3H), 7.14 (d, J = 16.0 Hz,
1H), 6.85 (d, J = 15.8 Hz, 1H), 6.70 (d, J = 8.7 Hz, 2H), 3.06 (s, 6H). MS
(ESI): m/z calcd for C18H17BrN2O, 356.05; found, 357.10 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(6-iodopyridin-3-yl)penta-
1,4-dien-3-one (47). Compound 47 was prepared following general
procedure A. Yield, 32.5%. 1H NMR (400 MHz, CDCL3): δ 8.50 (d, J =
2.5 Hz, 1H), 7.72 (d, J = 8.3 Hz, 1H), 7.69 (d, J = 15.8 Hz, 1H), 7.54 (d,
J = 16.0 Hz, 1H), 7.51ꢀ7.46 (m, 3H), 7.09 (d, J = 15.9 Hz, 1H), 6.80 (d,
J = 15.7 Hz, 1H), 6.65 (d, J = 8.9 Hz, 2H), 3.01 (s, 6H). MS (ESI): m/z
calcd for C18H17IN2O, 404.04; found, 405.10 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(1H-indol-5-yl)penta-1,4-
dien-3-one (55). Compound 55 was prepared following general proce-
dure A. Yield, 12.6%. 1H NMR (400 MHz, CDCL3): δ 8.33 (s, 1H), 7.90
(s, 1H), 7.88 (d, J = 15.9 Hz, 1H), 7.73 (d, J = 15.7 Hz, 1H), 7.54 (d, J =
8.9 Hz, 3H), 7.42 (d, J = 8.5 Hz, 1H), 7.25 (t, J = 2.8 Hz, 1H), 7.09 (d, J =
15.8 Hz, 1H), 6.93 (d, J = 15.8 Hz, 1H), 6.71 (d, J = 8.8 Hz, 2H),
6.64ꢀ6.59 (m, 1H), 3.05 (s, 6H). MS (ESI): m/z calcd for C21H20N2O,
316.16; found, 316.95 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(6-methoxynaphthalen-
2-yl)penta-1,4-dien-3-one (56). Compound 56 was prepared following
1
general procedure A. Yield, 43.8%. H NMR (400 MHz, CDCL3): δ
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(pyridin-2-yl)penta-1,4-dien-
3-one (48). Compound 48 was prepared following general procedure A.
Yield, 56.5%. 1H NMR (400 MHz, CDCL3): δ 8.68 (ddd, J = 4.7, 1.7, 0.8
Hz, 1H), 7.77 (d, J = 16.1 Hz, 1H), 7.72 (dd, J = 7.6, 1.9 Hz, 1H), 7.67 (d,
J = 5.3 Hz, 2H), 7.52 (d, J = 8.9 Hz, 2H), 7.47 (d, J = 7.8 Hz, 1H), 7.28
(dd, J = 4.8, 1.1 Hz, 1H), 6.89 (d, J = 15.8 Hz, 1H), 6.70 (d, J = 9.0 Hz,
2H), 3.05 (s, 6H). MS (ESI): m/z calcd for C18H18N2O, 278.14; found,
279.15 (M þ Hþ).
7.96 (s, 1H), 7.88 (d, J = 15.8 Hz, 1H), 7.84ꢀ7.73 (m, 4H), 7.56 (d, J =
8.9 Hz, 2H), 7.23ꢀ7.14 (m, 3H), 6.94 (d, J = 15.8 Hz, 1H), 6.73 (d, J =
8.9 Hz, 2H), 3.97 (s, 3H), 3.07 (s, 6H). MS (ESI): m/z calcd for
C24H23NO2, 357.17; found, 358.05 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(ferrocenyl)penta-1,4-dien-
3-one (57). Compound 57 was prepared following general procedure A.
Yield, 10.2%. 1H NMR (400 MHz, CDCL3): δ 7.68 (d, J = 15.7 Hz, 1H),
7.63 (d, J = 15.6 Hz, 1H), 7.52 (d, J = 8.9 Hz, 2H), 6.82 (d, J = 15.7 Hz,
1H), 6.70 (d, J = 8.8 Hz, 2H), 6.68 (d, J = 15.6 Hz, 1H), 4.57 (d, J = 1.8
Hz, 2H), 4.45 (d, J = 1.8 Hz, 2H), 4.17 (s, 5H), 3.04 (s, 6H). MS (ESI):
m/z calcd for C23H23FeNO, 385.13; found, 386.05 (M þ Hþ).
(1E,4E)-1,5-Diphenylpenta-1,4-dien-3-one (58). To a solution of
benzyaldehyde (2.0 mmol) and acetone (1.0 mmol) in 15 mL of ethanol
was added 0.2 mL of NaOMe (28% in methanol). The reaction mixture
was stirred for 12 h at room temperature. The precipitate was collected
by filtration, washed with water and hexane, and recrystallized from
ethanol. Yield, 15.7%. 1H NMR (400 MHz, CDCL3): δ 7.83 (d, J = 15.9
Hz, 2H), 7.71 (dd, J = 6.6, 2.9 Hz, 4H), 7.50 (dd, J = 4.9, 1.8 Hz, 4H),
7.17 (d, J = 15.9 Hz, 2H). MS (ESI): m/z calcd for C17H14O, 234.10;
found, 235.10 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(1H-pyrrol-2-yl)penta-1,4-
dien-3-one (49). Compound 49 was prepared following general proce-
dure A. Yield, 3.3%. 1H NMR (400 MHz, CDCL3): δ 7.72 (d, J = 15.6
Hz, 1H), 7.53 (d, J = 8.9 Hz, 2H), 7.08 (s, 1H), 6.84ꢀ6.77 (m, 2H), 6.71
(d, J = 8.9 Hz, 2H), 6.62 (d, J = 1.9 Hz, 1H), 6.36 (dd, J = 6.0, 2.4 Hz,
1H), 6.15 (d, J = 12.2 Hz, 1H), 3.07 (s, 6H). MS (ESI): m/z calcd for
C17H18N2O, 266.14; found, 267.15 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(furan-2-yl)penta-1,4-dien-
3-one (50). Compound 50 was prepared following general procedure A.
Yield, 83.9%. 1H NMR (400 MHz, CDCL3): δ 7.70 (d, J = 15.8 Hz, 1H),
7.51 (d, J = 8.8 Hz, 2H), 7.50 (d, J = 1.9 Hz, 1H), 7.48 (d, J = 15.5 Hz,
1H), 7.02 (d, J = 15.5 Hz, 1H), 6.81 (d, J = 15.8 Hz, 1H), 6.69 (d, J = 8.8
Hz, 2H), 6.66 (d, J = 3.2 Hz, 1H), 6.50 (dd, J = 3.3, 1.7 Hz, 1H), 3.04 (s,
6H). MS (ESI): m/z calcd for C17H17NO2, 267.13; found, 268.25 (M þ
Hþ).
(1E,4E)-1,5-Bis(4-chlorophenyl)penta-1,4-dien-3-one (59). The same
reaction described above to prepare 58 was used. Compound 59 was
obtained in a yield of 67.2%. 1H NMR (400 MHz, CDCL3): δ 7.68 (d,
J = 15.9 Hz, 2H), 7.54 (d, J = 8.4 Hz, 4H), 7.39 (d, J = 8.5 Hz, 4H), 7.03
(d, J = 16.0 Hz, 2H). MS (ESI): m/z calcd for C17H12Cl2O, 302.03;
found, 303.05 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(thiophen-2-yl)penta-1,4-
dien-3-one (51). Compound 51 was prepared following general proce-
dure A. Yield, 47.0%. 1H NMR (400 MHz, CDCL3): δ 7.98 (d, J = 15.2
Hz, 1H), 7.84 (d, J = 15.8 Hz, 1H), 7.66 (d, J = 8.9 Hz, 2H), 7.52 (d, J =
5.0 Hz, 1H), 7.46 (d, J = 3.2 Hz, 1H), 7.22 (dd, J = 4.8, 3.7 Hz, 1H), 7.04
(d, J = 15.5 Hz, 1H), 6.97 (d, J = 15.7 Hz, 1H), 6.84 (d, J = 8.9 Hz, 2H),
3.19 (s, 6H). MS (ESI): m/z calcd for C17H17NOS, 283.10; found,
284.10 (M þ Hþ).
(1E,4E)-1,5-Bis(4-methoxyphenyl)penta-1,4-dien-3-one (60). The
reaction described above to prepare 58 was used. Compound 60 was
obtained in a yield of 53.8%. 1H NMR (400 MHz, CDCL3): δ 7.71 (d,
J = 15.9 Hz, 2H), 7.58 (d, J = 8.8 Hz, 4H), 6.96 (d, J = 15.8 Hz, 2H), 6.94
(d, J = 8.8 Hz, 4H), 3.86 (s, 6H). MS (ESI): m/z calcd for C19H18O3,
294.13; found, 295.15 (M þ Hþ).
(1E,4E)-1-(5-Bromothiophen-2-yl)-5-(4-(dimethylamino)phenyl)penta-
1,4-dien-3-one (52). Compound 52 was prepared following general
procedure A. Yield, 71.0%. 1H NMR (400 MHz, CDCL3): δ 7.69 (d, J =
15.4 Hz, 1H), 7.68 (d, J = 15.8 Hz, 1H), 7.51 (d, J = 8.8 Hz, 2H),
(2E,6E)-2,6-Dibenzylidenecyclohexanone (61). To a solution of
benzyaldehyde (2.0 mmol) and cyclohexanone (1.0 mmol) in 15 mL
2235
dx.doi.org/10.1021/jm101404k |J. Med. Chem. 2011, 54, 2225–2240

Journal of Medicinal Chemistry
ARTICLE
of ethanol was added 0.2 mL of NaOMe (28% in methanol). The
reaction mixture was stirred for 12 h at room temperature. The
precipitate was collected by filtration, washed with water and hexane,
Yield, 63.1%. 1H NMR (400 MHz, CDCL3): δ 7.70 (d, J = 15.8 Hz, 1H),
7.62 (d, J = 15.9 Hz, 1H), 7.53 (d, J = 8.5 Hz, 2H), 7.48 (d, J = 8.3 Hz,
2H), 7.46 (d, J = 8.5 Hz, 2H), 7.06 (d, J = 15.9 Hz, 1H), 6.85 (d, J = 15.7
Hz, 1H), 6.59 (d, J = 8.6 Hz, 2H), 2.90 (s, 3H). MS (ESI): m/z calcd for
C18H16BrNO, 341.04; found, 342.10 (M þ Hþ).
1
and recrystallized from ethanol. Yield, 88.3%. H NMR (400 MHz,
CDCL3): δ 7.81 (s, 2H), 7.51ꢀ7.31 (m, 12H), 2.94 (dd, J = 8.3, 3.9 Hz,
4H), 1.80 (dt, J = 12.3, 6.3 Hz, 2H). MS (ESI): m/z calcd for C20H18O,
274.14; found, 275.10 (M þ Hþ).
(1E,4E)-1-(4-Aminophenyl)-5-(4-iodophenyl)penta-1,4-dien-3-one
(70). Compound 70 was prepared following general procedure A. Yield,
46.1%. 1H NMR (400 MHz, CDCL3): δ 7.74 (d, J = 8.4 Hz, 2H), 7.68
(d, J = 15.8 Hz, 1H), 7.61 (d, J = 15.9 Hz, 1H), 7.45 (d, J = 8.5 Hz, 2H),
7.33 (d, J = 8.4 Hz, 2H), 7.06 (d, J = 15.9 Hz, 1H), 6.87 (d, J = 15.8 Hz,
1H), 6.68 (d, J = 8.5 Hz, 2H), 4.01 (s, 2H). HRMS (EI): m/z (EIþ):
calcd for C17H14INO, 375.0120; found, 375.0116.
(2E,6E)-2,6-Bis(4-chlorobenzylidene)cyclohexanone (62). The same
reaction described above to prepare 61 was used. Compound 62 was
obtained in a yield of 71.2%. 1H NMR (400 MHz, CDCL3): δ7.73 (s, 2H),
7.38 (s, 8H), 2.89 (dd, J = 8.3, 3.9 Hz, 4H), 1.81 (dd, J = 12.0, 6.0 Hz, 2H).
MS (ESI): m/z calcd for C20H16Cl2O, 342.06; found, 343.10 (M þ Hþ).
(2E,6E)-2,6-Bis(4-methoxybenzylidene)cyclohexanone (63). The
same reaction described above to prepare 61 was used, and 63 was
obtained in a yield of 74.3%. 1H NMR (400 MHz, CDCL3): δ 7.76 (s,
2H), 7.45 (d, J = 8.8 Hz, 4H), 6.94 (d, J = 8.8 Hz, 4H), 3.84 (s, 6H),
3.05ꢀ2.84 (m, 4H), 1.81 (dd, J = 11.9, 5.8 Hz, 2H). MS (ESI): m/z calcd
for C22H22O3, 334.16; found, 335.05 (M þ Hþ).
(1E,4E)-1-(4-Iodophenyl)-5-(4-(methylamino)phenyl)penta-1,4-
dien-3-one (71). Compound 71 was prepared following general proce-
1
dure A. Yield, 53.2%. H NMR (400 MHz, CDCL3): δ 7.74 (d, J =
8.4 Hz, 2H), 7.70 (d, J = 15.8 Hz, 1H), 7.61 (d, J = 15.8 Hz, 1H), 7.48 (d,
J = 8.7 Hz, 2H), 7.33 (d, J = 8.5 Hz, 2H), 7.07 (d, J = 15.9 Hz, 1H), 6.85
(d, J = 15.8 Hz, 1H), 6.60 (d, J = 8.7 Hz, 2H), 4.18 (s, 1H), 2.90 (s, 3H).
HRMS (EI): m/z (EIþ): calcd for C18H16INO, 389.0277; found, 389.0281.
(1E,4E)-1-(4-Aminophenyl)-5-(4-(tributylstannyl)phenyl)penta-1,4-
dien-3-one (72). A mixture of 68 (125 mg, 0.38 mmol), (Bu3Sn)2
(440.9 mg, 0.76 mmol), and (Ph3P)4Pd (47 mg, 0.04 mmol) in toluene
(10 mL) was stirred under reflux for 10 h. The solvent was removed, and
the residue was purified by silica gel chromatography to give 46.8 mg of
72 (22.9%). 1H NMR (400 MHz, CDCL3): δ 7.69 (d, J = 15.9 Hz, 1H),
7.68 (d, J = 15.8 Hz, 1H), 7.54 (d, J = 8.4 Hz, 2H), 7.51 (d, J = 8.1 Hz,
2H), 7.45 (d, J = 8.5 Hz, 2H), 7.08 (d, J = 15.9 Hz, 1H), 6.90 (d, J = 15.8
Hz, 1H), 6.67 (d, J = 8.5 Hz, 2H), 4.00 (s, 1H), 1.71ꢀ0.71 (m, 27H). MS
(ESI): m/z calcd for C29H41NOSn, 539.22; found, 540.30 (M þ Hþ).
(1E,4E)-1-(4-(Methylamino)phenyl)-5-(4-(tributylstannyl)phenyl)
penta-1,4-dien-3-one (73). The same reaction described above to
prepare 72 was used. Compound 73 was obtained in a yield of 30.2%.
1H NMR (400 MHz, CDCL3): δ 7.69 (d, J = 15.8 Hz, 1H), 7.69 (d, J =
15.9 Hz, 1H), 7.54 (d, J = 8.0 Hz, 2H), 7.53 (d, J = 8.0 Hz, 2H), 7.48 (d,
J = 8.6 Hz, 2H), 7.09 (d, J = 15.9 Hz, 1H), 6.88 (d, J = 15.7 Hz, 1H), 6.60
(d, J = 8.4 Hz, 2H), 4.12 (s, 1H), 2.90 (s, 3H), 1.82ꢀ0.58 (m, 27H). MS
(ESI): m/z calcd for C30H43NOSn, 552.24; found, 553.25 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(4-(tributylstannyl)phenyl)
penta-1,4-dien-3-one (74). The reaction described above to prepare 72
was used, and 74 was obtained in a yield of 26.9%. 1H NMR (400 MHz,
CDCL3): δ 7.71 (d, J = 15.7 Hz, 1H), 7.69 (d, J = 15.9 Hz, 1H),
7.60ꢀ7.44 (m, 6H), 7.10 (d, J = 15.9 Hz, 1H), 6.88 (d, J = 15.8 Hz, 1H),
6.69 (d, J = 8.9 Hz, 2H), 3.03 (s, 6H), 1.82ꢀ0.77 (m, 27H). MS (ESI):
m/z calcd for C31H45, 567.25; found, 568.25 (M þ Hþ).
(2E,6E)-2,6-Bis(4-(dimethylamino)benzylidene)cyclohexanone (64).
The same reaction described above to prepare 61 was used, and 64 was
obtained in a yield of 12.3%. 1H NMR (400 MHz, CDCL3): δ 7.75 (s,
2H), 7.44 (d, J = 8.9 Hz, 4H), 6.71 (d, J = 8.9 Hz, 4H), 3.01 (s, 12H),
2.96ꢀ2.90 (m, 4H), 1.82 (dd, J = 11.8, 5.7 Hz, 2H). MS (ESI): m/z calcd
for C24H28N2O, 360.22; found, 361.15 (M þ Hþ).
(E)-4-(4-Nitrophenyl)but-3-en-2-one (65). To a solution of 4-nitro-
benzaldehyde (6.04 g, 50 mmol) in 150 mL of acetone were added 1.38 g
of K2CO3 and 10 mL of water, and the reaction mixture was stirred for
12 h at room temperature. Then, 20 mL of concentrated HCl was added,
and the mixture was stirred for an additional 6 h at room temperature.
After 300 mL of water was added, the white precipitate formed was
collected by filtration, washed with water, and dried under vacuum to
obtain 8.34 g of 65 (87.2%). 1H NMR (400 MHz, CDCL3): δ 8.26 (d, J
= 8.9 Hz, 2H), 7.70 (d, J = 8.8 Hz, 2H), 7.54 (d, J = 16.3 Hz, 1H), 6.82 (d,
J = 16.3 Hz, 1H), 2.42 (s, 3H). MS (ESI): m/z calcd for C10H9NO3,
191.06; found, 192.10 (M þ Hþ).
(E)-4-(4-Aminophenyl)but-3-en-2-one (66). A mixture of 65 (1.92 g,
10 mmol) and SnCl2 (3.79 g, 20 mmol) dissolved in 80 mL of ethanol
containing 5 mL of concentrated hydrochloric acid was stirred under
reflux for 2 h. After the mixture was cooled to room temperature, 2 M
NaOH (100 mL) was added and extracted with ethyl acetate (100 mL).
The organic layer was dried over Na2SO4. The solvent was removed, and
the residue was purified by silica gel chromatography to give 1.16 g of 66
(72.1%). 1H NMR (400 MHz, CDCL3): δ 7.44 (d, J = 16.2 Hz, 1H),
7.37 (d, J = 8.7 Hz, 2H), 6.66 (d, J = 8.6 Hz, 2H), 6.55 (d, J = 16.1 Hz,
1H), 4.00 (s, 2H), 2.34 (s, 3H). MS (ESI): m/z calcd for C10H11NO,
161.08; found, 162.10 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(4-(2-hydroxyethoxy)phenyl)
penta-1,4-dien-3-one (75). Compound 75 was prepared following
1
general procedure A. Yield, 89.8%. H NMR (400 MHz, CDCL3): δ
(E)-4-(4-(Methylamino)phenyl)but-3-en-2-one (67). To a solution
of 66 (483 mg, 3 mmol) and 414 mg of K2CO3 in 50 mL of acetone was
added CH3I (852 mg, 6 mmol) dropwise, and the reaction mixture was
stirred for 8 h at room temperature. After filtration, the solvent was
removed, and the residue was purified by silica gel chromatography to
give 183.5 mg of 67 (34.9%). 1H NMR (400 MHz, CDCL3): δ 7.45 (d,
J = 16.1 Hz, 1H), 7.40 (d, J = 8.7 Hz, 2H), 6.58 (d, J = 8.7 Hz, 2H), 6.54
(d, J = 16.1 Hz, 1H), 4.13 (s, 1H), 2.88 (s, 3H), 2.33 (s, 3H). MS (ESI):
m/z calcd for C11H13NO, 175.10; found, 176.15 (M þ Hþ).
7.71 (d, J = 15.5 Hz, 1H), 7.68 (d, J = 15.8 Hz, 1H), 7.57 (d, J = 8.1 Hz,
2H), 7.52 (d, J = 8.2 Hz, 2H), 6.98 (d, J = 16.0 Hz, 1H), 6.95 (d, J = 8.0
Hz, 2H), 6.88 (d, J = 15.8 Hz, 1H), 6.70 (d, J = 8.2 Hz, 2H), 4.14 (t, J =
4.0 Hz, 2H), 4.05ꢀ3.92 (m, 2H), 3.05 (s, 6H). MS (ESI): m/z calcd for
C21H23NO3, 337.17; found, 338.10 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(4-(2-(2-hydroxyethoxy)-
ethoxy)phenyl)penta-1,4-dien-3-one (76). Compound 76 was pre-
pared following general procedure A. Yield, 84.3%. 1H NMR (400
MHz, CDCL3): δ 7.70 (d, J = 15.8 Hz, 1H), 7.67 (d, J = 15.8 Hz, 1H),
7.56 (d, J = 8.8 Hz, 2H), 7.52 (d, J = 8.9 Hz, 2H), 6.97 (d, J = 15.2 Hz,
1H), 6.94 (d, J = 8.6 Hz, 2H), 6.87 (d, J = 15.8 Hz, 1H), 6.70 (d, J = 8.8
Hz, 2H), 4.29ꢀ4.11 (m, 2H), 3.96ꢀ3.84 (m, 2H), 3.80ꢀ3.75 (m, 2H),
3.72ꢀ3.65 (m, 2H), 3.04 (s, 6H). MS (ESI): m/z calcd for C23H27NO4,
381.19; found, 382.10 (M þ Hþ).
(1E,4E)-1-(4-Aminophenyl)-5-(4-bromophenyl)penta-1,4-dien-3-one
(68). Compound 68 was prepared following general procedure A. Yield,
55.7%. 1H NMR (400 MHz, CDCL3): δ 7.68 (d, J = 15.8 Hz, 1H), 7.63
(d, J = 15.9 Hz, 1H), 7.54 (d, J = 8.5 Hz, 2H), 7.46 (d, J = 8.5 Hz, 2H),
7.45 (d, J = 8.5 Hz, 2H), 7.05 (d, J = 15.9 Hz, 1H), 6.87 (d, J = 15.8 Hz,
1H), 6.68 (d, J = 8.6 Hz, 2H), 4.01 (s, 1H). MS (ESI): m/z calcd for
C17H14BrNO, 327.03; found, 328.05 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(4-(2-(2-(2-hydroxyethox-
y)ethoxy)ethoxy)phenyl)penta-1,4-dien-3-one (77). Compound 77
(1E,4E)-1-(4-Bromophenyl)-5-(4-(methylamino)phenyl)penta-1,4-dien-
3-one (69). Compound 69 was prepared following general procedure A.
1
was prepared following general procedure A. Yield, 79.2%. H NMR
2236
dx.doi.org/10.1021/jm101404k |J. Med. Chem. 2011, 54, 2225–2240

Journal of Medicinal Chemistry
ARTICLE
(400 MHz, CDCL3): δ 7.70 (d, J = 12.0 Hz, 1H), 7.67 (d, J = 12.1 Hz,
1H), 7.55 (d, J = 8.8 Hz, 2H), 7.52 (d, J = 8.9 Hz, 2H), 6.97 (d, J = 13.9
Hz, 2H), 6.94 (d, J = 6.8 Hz, 1H), 6.87 (d, J = 15.7 Hz, 1H), 6.69 (d, J =
8.9 Hz, 2H), 4.19ꢀ4.16 (m, 2H), 3.91ꢀ3.85 (m, 2H), 3.77ꢀ3.68 (m,
6H), 3.66ꢀ3.59 (m, 2H), 3.04 (s, 6H). MS (ESI): m/z calcd for
C25H31NO5, 425.22; found, 426.25 (M þ Hþ).
1H NMR (400 MHz, CDCL3): δ 7.70 (d, J = 15.5 Hz, 1H), 7.67 (d, J =
15.5 Hz, 1H), 7.55 (d, J = 7.2 Hz, 2H), 7.51 (d, J = 7.7 Hz, 2H), 6.97 (d,
J = 16.0 Hz, 1H), 6.93 (d, J = 8.8 Hz, 2H), 6.86 (d, J = 15.7 Hz, 1H), 6.68
(d, J = 7.7 Hz, 2H), 4.67ꢀ4.59 (m, 1H), 4.53ꢀ4.45 (m, 1H), 4.17 (t, J =
3.9 Hz, 2H), 3.88 (t, J = 3.9 Hz, 2H), 3.83ꢀ3.77 (m, 1H), 3.77ꢀ3.67 (m,
5H), 3.03 (s, 6H). HRMS (EI): m/z (EIþ): calcd for C25H30FNO4,
427.2159; found, 427.2152.
2-(4-((1E,4E)-5-(4-(Dimethylamino)phenyl)-3-oxopenta-1,4-dien-1-yl)-
phenoxy)ethyl 4-methylbenzenesulfonate (78). To a solution of 75
(101 mg, 0.3 mmol) in pyridine (8 mL) was added tosyl chloride (69 mg,
0.36 mmol). The reaction mixture was stirred for 3 h at room
temperature, 50 mL of water was added, and the mixture was extracted
with CHCl3. The organic layer was dried over Na2SO4, and evaporation
of the solvent afforded a residue, which was purified by silica gel
chromatography to give 69.2 mg of 78 (46.9%). 1H NMR (400 MHz,
CDCL3): δ 7.82 (d, J = 8.3 Hz, 2H), 7.70 (d, J = 15.8 Hz, 1H), 7.65 (d,
J = 15.9 Hz, 1H), 7.52 (d, J = 8.8 Hz, 2H), 7.52 (d, J = 9.0 Hz, 2H), 6.97
(d, J = 15.8 Hz, 1H), 6.86 (d, J = 15.7 Hz, 1H), 6.80 (d, J = 8.8 Hz, 2H),
6.70 (d, J = 8.9 Hz, 2H), 4.50ꢀ4.32 (m, 2H), 4.19 (dd, J = 5.5, 3.9 Hz,
2H), 3.04 (s, 6H), 2.45 (s, 3H). MS (ESI): m/z calcd for C28H29NO5S,
491.18; found, 492.34 (M þ Hþ).
4-(2-(2-(2-Fluoroethoxy)ethoxy)ethoxy)benzaldehyde (84). To a
solution of 4-(2-(2-(2-hydroxyethoxy)ethoxy)ethoxy)benzaldehyde
(508 mg, 2 mmol) in CHCl3 (5 mL) was added DAST (645 mg,
4 mmol) in a dry iceꢀacetone bath. The reaction mixture was stirred for
2 h at room temperature and then poured into a saturated NaHSO3
solution and extracted with chloroform. The organic phase was sepa-
rated, dried over MgSO4, and filtered, and the residue was purified by
silica gel chromatography to give 299 mg of 84 (58.3%). 1H NMR (400
MHz, CDCL3): δ 9.88 (s, 1H), 7.83 (d, J = 8.9 Hz, 2H), 7.02 (d, J = 8.8
Hz, 2H), 4.62 (dd, J = 4.6, 3.7 Hz, 1H), 4.50 (dd, J = 4.7, 3.7 Hz, 1H),
4.22 (dd, J = 5.4, 4.2 Hz, 2H), 3.90 (dd, J = 5.4, 4.2 Hz, 2H), 3.83ꢀ3.67
(m, 6H). MS (ESI): m/z calcd for C13H17FO4, 256.11; found, 257.10
(M þ Hþ).
2-(2-(4-((1E,4E)-5-(4-(Dimethylamino)phenyl)-3-oxopenta-1,4-dien-
1-yl)phenoxy)ethoxy)ethyl 4-Methylbenzenesulfonate (79). The same
reaction described above to prepare 78 was used. Compound 79 was
obtained in a yield of 37.5%. 1H NMR (400 MHz, CDCL3): δ 7.80 (d,
J = 8.3 Hz, 2H), 7.70 (d, J = 15.7 Hz, 1H), 7.67 (d, J = 15.7 Hz, 1H), 7.55
(d, J = 8.7 Hz, 2H), 7.52 (d, J = 8.9 Hz, 2H), 7.30 (d, J = 8.4 Hz, 2H), 6.98
(d, J = 15.8 Hz, 1H), 6.91 (d, J = 8.8 Hz, 2H), 6.87 (d, J = 15.8 Hz, 1H),
6.70 (d, J = 8.9 Hz, 2H), 4.23ꢀ4.16 (m, 2H), 4.14ꢀ4.02 (m, 2H),
3.90ꢀ3.66 (m, 4H), 3.04 (s, 6H), 2.41 (s, 3H). MS (ESI): m/z calcd for
C30H33NO6S, 535.20; found, 536.17 (M þ Hþ).
(1E,4E)-1-(4-(2-(2-(2-Fluoroethoxy)ethoxy)ethoxy)phenyl)-5-(4-
(methylamino)phenyl)penta-1,4-dien-3-one (85). Compound 85 was
1
prepared following general procedure A. Yield, 67.2%. H NMR (400
MHz, CDCL3): δ 7.68 (d, J = 15.8 Hz, 1H), 7.67 (d, J = 15.8 Hz, 1H),
7.54 (d, J = 8.8 Hz, 2H), 7.47 (d, J = 8.7 Hz, 2H), 6.96 (d, J = 15.8 Hz,
1H), 6.93 (d, J = 8.8 Hz, 2H), 6.86 (d, J = 15.8 Hz, 1H), 6.58 (d, J = 8.7
Hz, 2H), 4.62 (dd, J = 4.7, 3.7 Hz, 1H), 4.50 (dd, J = 4.7, 3.7 Hz, 1H),
4.26ꢀ4.11 (m, 2H), 3.88 (dd, J = 5.4, 4.2 Hz, 2H), 3.83ꢀ3.66 (m, 6H),
2.87 (s, 3H). HRMS (EI): m/z (EIþ): calcd for C24H28FNO4, 413.2002;
found, 413.2007.
2-(2-(2-(4-((1E,4E)-5-(4-(Dimethylamino)phenyl)-3-oxopenta-1,4-
dien-1-yl)phenoxy)ethoxy)ethoxy)ethyl 4-Methylbenzenesulfonate
(80). The reaction described above to prepare 78 was used, and 80 was
obtained in a yield of 58.8%. 1H NMR (400 MHz, CDCL3): δ 7.80 (d,
J = 8.2 Hz, 2H), 7.70 (d, J = 15.7 Hz, 1H), 7.67 (d, J = 15.8 Hz, 1H), 7.55
(d, J = 8.7 Hz, 2H), 7.52 (d, J = 8.8 Hz, 2H), 7.33 (d, J = 8.1 Hz, 2H), 6.97
(d, J = 15.9 Hz, 1H), 6.93 (d, J = 8.7 Hz, 2H), 6.87 (d, J = 15.7 Hz, 1H),
6.70 (d, J = 8.8 Hz, 2H), 4.16 (dd, J = 8.9, 4.0 Hz, 2H), 3.90ꢀ3.80 (m,
2H), 3.73ꢀ3.68 (m, 2H), 3.64 (ddd, J = 9.0, 5.6, 3.5 Hz, 4H), 3.04 (s,
6H), 2.43 (s, 3H). MS (ESI): m/z calcd for C32H37NO7S, 579.23;
found, 580.39 (M þ Hþ).
(1E,4E)-1-(4-(2-(2-(2-Hydroxyethoxy)ethoxy)ethoxy)phenyl)-5-
(4-(methylamino)phenyl)penta-1,4-dien-3-one (86). Compound 86
1
was prepared following general procedure A. Yield, 70.5%. H NMR
(400 MHz, CDCL3): δ 7.68 (d, J = 15.8 Hz, 1H), 7.66 (d, J = 15.8 Hz,
1H), 7.54 (d, J = 8.8 Hz, 2H), 7.47 (d, J = 8.7 Hz, 2H), 6.95 (d, J = 15.8
Hz, 1H), 6.93 (d, J = 8.8 Hz, 2H), 6.85 (d, J = 15.7 Hz, 1H), 6.58 (d, J =
8.7 Hz, 2H), 4.20ꢀ4.13 (m, 2H), 3.93ꢀ3.83 (m, 2H), 3.72 (ddd, J = 5.8,
4.6, 2.8 Hz, 6H), 3.65ꢀ3.58 (m, 2H), 2.88 (s, 3H). MS (ESI): m/z calcd
for C24H29NO5, 411.20; found, 412.40 (M þ Hþ).
(1E,4E)-1-(4-(Methylamino)phenyl)-5-(4-((2,2,3,3-tetramethyl-4,7,
10-trioxa-3-siladodecan-12-yl)oxy)phenyl)penta-1,4-dien-3-one (87).
Compound 86 (659 mg, 1.60 mmol) and TBDMSCl (386 mg, 2.56
mmol) were dissolved in dichloromethane (15 mL) followed by
imidazole (120 mg, 3.20 mmol). The solution was stirred at room
temperature for 2 h. A white solid formed and was filtered off. After the
filtrate was evaporated, the residue was purified by silica gel column
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(4-(2-fluoroethoxy)phenyl)-
penta-1,4-dien-3-one (81). To a solution of 78 (100 mg, 0.2 mmol) in
15 mL of dry tetrahydrofuran (THF) was added anhydrous TBAF (400
μL, 1 M in THF). The reaction mixture was refluxed for 3 h. After
removal of the THF, the residue was purified by silica gel chromatog-
raphy to give 33.9 mg of 81 (50.0%). 1H NMR (400 MHz, CDCL3): δ
7.71 (d, J = 15.7 Hz, 1H), 7.68 (d, J = 15.7 Hz, 1H), 7.57 (d, J = 8.8 Hz,
2H), 7.52 (d, J = 8.9 Hz, 2H), 6.98 (d, J = 15.1 Hz, 1H), 6.95 (d, J = 8.6
Hz, 2H), 6.87 (d, J = 15.7 Hz, 1H), 6.70 (d, J = 8.8 Hz, 2H), 5.09ꢀ4.58
(m, 2H), 4.27 (dd, J = 27.6, 4.2 Hz, 2H), 3.04 (s, 6H). MS (ESI): m/z
calcd for C21H22FNO2, 339.16; found, 340.17 (M þ Hþ).
1
chromatography to afford 87 (502 mg, 59.5%). H NMR (400 MHz,
CDCL3): δ 7.61 (d, J = 15.7 Hz, 1H), 7.59 (d, J = 15.8 Hz, 1H), 7.44 (d,
J = 8.7 Hz, 2H), 7.36 (d, J = 8.6 Hz, 2H), 6.88 (d, J = 15.9 Hz, 1H), 6.84
(d, J = 8.7 Hz, 2H), 6.77 (d, J = 15.7 Hz, 1H), 6.48 (d, J = 8.6 Hz, 2H),
4.46 (s, 1H), 4.05 (t, J = 5.3 Hz, 2H), 3.77 (t, J = 5.3 Hz, 2H), 3.70 (t, J =
5.3 Hz, 2H), 3.68ꢀ3.57 (m, 4H), 3.49 (t, J = 5.3 Hz, 2H), 2.74 (s, 3H),
0.83 (s, 9H). MS (ESI): m/z calcd for C30H43NO5Si, 525.29; found,
526.29 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(4-(2-(2-fluoroethoxy)-
ethoxy)phenyl)penta-1,4-dien-3-one (82). The same reaction de-
scribed above to prepare 81 was used. Compound 82 was obtained in
a yield of 41.3%. 1H NMR (400 MHz, CDCL3): δ 7.70 (d, J = 15.7 Hz,
1H), 7.67 (d, J = 15.8 Hz, 1H), 7.56 (d, J = 8.7 Hz, 2H), 7.52 (d, J = 8.9
Hz, 2H), 6.97 (d, J = 14.9 Hz, 1H), 6.95 (d, J = 8.6 Hz, 2H), 6.87 (d, J =
15.7 Hz, 1H), 6.70 (d, J = 8.9 Hz, 2H), 4.67ꢀ4.53 (m, 1H), 4.28ꢀ4.11
(m, 2H), 4.02ꢀ3.75 (m, 4H), 3.66 (t, J = 5.9 Hz, 1H), 3.04 (s, 6H). MS
(ESI): m/z calcd for C23H26FNO3, 383.19; found, 384.21 (M þ Hþ).
(1E,4E)-1-(4-(Dimethylamino)phenyl)-5-(4-(2-(2-(2-fluoroethoxy)-
ethoxy)ethoxy)phenyl)penta-1,4-dien-3-one (83). The reaction described
above to prepare 81 was used, and 83 was obtained in a yield of 36.6%.
tert-Butylmethyl(4-((1E,4E)-3-oxo-5-(4-((2,2,3,3-tetramethyl-4,7,
10-trioxa-3-siladodecan-12-yl)oxy)phenyl)penta-1,4-dien-1-yl)phenyl)-
carbamate (88). Under a nitrogen atmosphere, 87 (491 mg, 0.94
mmol) was dissolved in anhydrous THF (20 mL) followed by Boc-
anhydride (408 mg, 1.87 mmol). The solution was refluxed for 48 h.
After the reaction was complete, the solvent was removed, and the
residue was purified by silica gel column chromatography to afford 88
(433 mg, 74.1%). 1H NMR (400 MHz, CDCL3): δ 7.64 (d, J = 15.9 Hz,
1H), 7.63 (d, J = 15.9 Hz, 1H), 7.51 (d, J = 3.6 Hz, 2H), 7.49 (d, J =
3.9 Hz, 2H), 7.24 (d, J = 8.6 Hz, 2H), 6.95 (d, J = 15.9 Hz, 1H), 6.89
2237
dx.doi.org/10.1021/jm101404k |J. Med. Chem. 2011, 54, 2225–2240

Journal of Medicinal Chemistry
ARTICLE
(d, J = 16.0 Hz, 1H), 6.87 (s, J = 8.5 Hz, 2H), 4.17ꢀ4.06 (m, 2H),
3.84ꢀ3.80 (m, 2H), 3.71 (t, J = 5.4 Hz, 2H), 3.64 (qdd, J = 4.8, 3.7, 1.8 Hz,
4H), 3.51 (t, J = 5.4 Hz, 2H), 3.23 (s, 3H), 1.41 (s, 9H), 0.83 (s, 9H). MS
(ESI): m/z calcd for C35H51NO7Si, 625.34; found, 626.30 (M þ Hþ).
tert-Butyl(4-((1E,4E)-5-(4-(2-(2-(2-hydroxyethoxy)ethoxy)ethoxy)-
phenyl)-3-oxopenta-1,4-dien-1-yl)phenyl)(methyl)carbamate (89).
To a solution of 88 (433 mg, 0.69 mmol) in dry THF (15 mL) was
added anhydrous TBAF (1.4 mL, 1 M in THF). The solution was stirred
at room temperature for 2 h. After removal of the THF, the residue was
purified by silica gel chromatography to give 300 mg of 89 (85.0%). 1H
NMR (400 MHz, CDCL3): δ 7.70 (d, J = 15.9 Hz, 1H), 7.69 (d, J = 15.9
Hz, 1H), 7.57 (d, J = 5.2 Hz, 2H), 7.55 (d, J = 5.3 Hz, 2H), 7.31 (d, J = 8.4
Hz, 2H), 7.02 (d, J = 15.9 Hz, 1H), 6.96 (d, J = 16.3 Hz, 1H), 6.95 (d, J =
8.3 Hz, 2H), 4.21ꢀ4.14 (m, 2H), 3.92ꢀ3.84 (m, 2H), 3.76ꢀ3.66 (m,
6H), 3.65ꢀ3.58 (m, 2H), 3.29 (s, 3H), 1.48 (s, 9H). MS (ESI): m/z
calcd for C29H37NO7, 511.26; found, 534.35 (M þ Naþ).
system (CH3CN/water = 7/3; flow rate = 4 mL/min). The preparation
took 40 min, and the radiochemical yield was 49% (decay corrected). For
[18F]85, a solution of the mesylate precursor 90 (1.0 mg) in DMSO
(0.2 mL) was added to the reaction vessel containing the 18Fꢀ activity.
The mixture was heated at 120 °C for 5 min. Water (2 mL) was added,
and the solution was cooled down for 1 min. HCl (1 M aqueous solution,
2 mL) was then added, and the mixture was heated at 120 °C again for 5
min. An aqueous solution of K2CO3 was added to adjust the pH to basic
(pH 8ꢀ9). The mixture was extracted with ethyl acetate (1 mL ꢁ 2), the
combined organic layer was dried (Na2SO4), and the solvent was
removed. The residue was dissolved in CH3CN and subjected to HPLC
for purification (Waters, 5C18-AR-II, 10 mm ꢁ 150 mm, CH3CN/water
= 1/1; flow rate = 4 mL/min). The retention time of [18F]85 was 6.6 min
in this HPLC system. The preparation took 80 min, and the radio-
chemical yield was 13% (decay corrected). The radiochemical purity of
both tracers was greater than 98% with an estimated specific activity of
900ꢀ1500 Ci/mmol.
2-(2-(2-(4-((1E,4E)-5-(4-((tert-Butoxycarbonyl)(methyl)amino)phenyl)
-3-oxopenta-1,4-dien-1-yl)phenoxy)ethoxy)ethoxy)ethyl methanesul-
fonate (90). Compound 89 (290 mg, 0.567 mmol) was dissolved in
dichloromethane (15 mL) followed by triethylamine (287.2 mg, 2.84
mmol). Methanesulfonyl chloride (195 mg, 1.70 mmol) was then added
via a syringe. The solution was stirred at room temperature for 4 h. Next,
50 mL of water was added and extracted with CHCl3 (3 ꢁ 50 mL). The
organic layer was dried over MgSO4. After the solvent was removed, the
residue was purified by silica gel chromatography to afford 90 (214 mg,
64%). 1H NMR (400 MHz, CDCL3): δ 7.70 (d, J = 15.8 Hz, 1H), 7.69
(d, J = 16.0 Hz, 1H), 7.58 (d, J = 3.1 Hz, 2H), 7.56 (d, J = 3.3 Hz, 2H),
7.31 (d, J = 8.5 Hz, 2H), 7.03 (d, J = 15.9 Hz, 1H), 6.97 (d, J = 15.8 Hz,
1H), 6.94 (d, J = 8.5 Hz, 2H), 4.44ꢀ4.29 (m, 2H), 4.23ꢀ4.02 (m, 2H),
3.91ꢀ3.79 (m, 2H), 3.79ꢀ3.75 (m, 2H), 3.74ꢀ3.64 (m, 4H), 3.29 (s,
3H), 3.05 (s, 3H), 1.48 (s, 9H). MS (ESI): m/z calcd for C30H39NO9S,
589.23; found, 590.25 (M þ Hþ).
Binding Assay in Vitro Using Aβ Aggregates. Inhibition
experiments were carried out in 12 mm ꢁ 75 mm borosilicate glass
tubes according to procedures described previously with some
modifications.22 Briefly, 100 μL of aggregated Aβ fibrils (60 nM in the
final assay mixture) was added to a mixture containing 100 μL of
radioligands ([125I]IMPY) at an appropriate concentration, 10 μL of
inhibitors (10ꢀ5ꢀ10ꢀ10 M in ethanol), and 790 μL of PBS (0.2 M, pH =
7.4) in a final volume of 1 mL. Nonspecific binding was defined in the
presence of 1 μM IMPY. The mixture was incubated for 2 h at 37 °C with
constant shaking, and then, the bound and free radioactive fractions were
separated by vacuum filtration through borosilicate glass fiber filters
(Whatman GF/B) using a M-24 cell harvester (Brandel, Gaithersburg,
MD). The radioactivity from filters containing the bound 125I ligand was
measured in a γ-counter (WALLAC/Wizard 1470, United States) with
70% efficiency. Under the assay conditions, the specifically bound
fraction accounted for about 10% of total radioactivity. The half maximal
inhibitory concentration (IC50) was determined using GraphPad Prism 4.0,
and the inhibition constant (Ki) was calculated using the ChengꢀPrusoff
equation: Ki = IC50/(1 þ [L]/Kd).40
Radiolabeling. Procedure for Labeling of [125I]6, [125I]70, and
[
125I]71. The radioiodinated ligands [125I]6, [125I]70, and [125I]71 were
prepared from the corresponding tributyltin precursors through an
iododestannylation reaction using hydrogen peroxide as an oxidant with
radiochemical yields of 27.6, 15.3, and 24.1%, respectively. After
purification by HPLC, the radiochemical purity of these ligands was
greater than 98% [HPLC conditions: Waters 5C18-AR-II column
(Analytical 4.6 mm ꢁ 150 mm) CH3CN/H2O = 6/4, 1 mL/min for
70, CH3CN/H2O = 7/3, 1 mL/min for 71, and CH3CN/H2O = 8/2,
1 mL/min for 6]. The specific activity of the no carrier-added prepara-
tion was comparable to that of Na125I, 2200 Ci/mmol. Finally, the
radiochemical identity of the radioiodinated ligands was verified by
coinjection with nonradioactive compounds using HPLC profiles. The
final product was stored at ꢀ20 °C for autoradiography and biodistribu-
tion experiments.
Autoradiography in Vitro Using Tg Mouse Brains. Paraffin-
embedded mouse brain sections (C57BL6-APP/PS1, 12 months old, male)
and wild-type control mouse brain sections (C57BL6, 12 months old, male)
were deparaffinized with 2 ꢁ 20 min washes in xylene, 2 ꢁ 5 min washes
in 100% ethanol, a 5 min wash in 90% ethanol/H2O, a 5 min wash in 80%
ethanol/H2O, a 5 min wash in 60% ethanol/H2O, and a 10 min wash in
running tap water, and then incubated in PBS (0.2 M, pH = 7.4) for 30
min. The sections were incubated with radiolabeled tracers (5 μCi/100
μL) for 1 h at room temperature, then washed with 40% ethanol for 3
min, and rinsed with water for 30 s. After they were dried, the labeled
sections were exposed to a Fuji Film imaging plate overnight. The in vitro
autoradiographic images were obtained using a BAS5000 scanner system
(Fuji Film). The presence and location of plaques in the sections were
confirmed with fluorescent staining using thioflavin S.
Autoradiography in Vitro Using Human AD Brains. Paraffin-
embedded postmortem brain sections (Temporal lobe) of an AD patient
(75 year old male) and normal control brain sections (20 year old male)
were obtained from BioChain. The same protocol was employed as for
the Tg mouse brains. Finally, the presence and location of plaques in the
sections were confirmed with immunohistochemical staining using a
monoclonal Aβ1ꢀ42 antibody, BC05 (Wako).
Procedure for Labeling of [18F]83 and [18F]85. [18F]Fluoride was
produced by the JSW typeBC3015 cyclotron via an 18O(p,n)18F reaction
and passed through a Sep-Pak Light QMA cartridge (Waters) as an
aqueous solution in 18O-enriched water. The cartridge was dried by
airflow, and the 18Fꢀ activity was eluted with a K2CO3 solution (33 mM).
Kryptofix222 (6ꢀ8 mg) was dissolved in the solution of [18F]fluoride in
water. The solvent was removed at 120 °C under a stream of nitrogen gas.
The residue was azeotropically dried with 0.3 mL of anhydrous acetoni-
trile twice at 120 °C under a stream of nitrogen gas. For [18F]83, a
solution of the tosylate precursor 80 (1.0 mg) in DMSO (0.2 mL) was
added to the reaction vessel containing the 18Fꢀ activity. The mixture was
heated at 120 °C for5 min. Water (3 mL) was added, and the mixture was
passed through a preconditioned Sep-Pak Plus-C18 cartridge (Waters).
The cartridge was washed with 10 mL of water, and the labeled
compound was eluted with 2 mL of acetonitrile. The eluted compound
was purified by semipreparative HPLC (Waters, 5C18-AR-II, 10 mm ꢁ
150 mm). The retention time of [18F]83 was 13.1 min in this HPLC
Biodistribution Experiments in Vivo Using Normal ddY
Mice. The biodistribution experiments were performed in normal
female ddY mice (5 weeks, average weight, about 20 g) and approved
by the animal care committee of Kyoto University. A saline solution
containing the radiolabeled tracers (1 μCi/100 μL for radioiodinated
tracers, 10 μCi/100 μL for radiofluorinated tracers) was injected directly
into the tail. The mice were sacrificed at various time points
2238
dx.doi.org/10.1021/jm101404k |J. Med. Chem. 2011, 54, 2225–2240

Journal of Medicinal Chemistry
ARTICLE
postinjection. The organs of interest were removed and weighed, and the
radioactivity was measured with an automatic γ-counter (WALLAC/
Wizard 1470). The percent dose per gram of wet tissue was calculated by
a comparison of the tissue counts to suitably diluted aliquots of the
injected material.
(5) Klein, W. L.; Krafft, G. A.; Finch, C. E. Targeting small Aβ
oligomers: The solution to an Alzheimer's disease conundrum? Trends
Neurosci. 2001, 24, 219–224.
(6) McLean, C. A.; Cherny, R. A.; Fraser, F. W.; Fuller, S. J.; Smith,
M. J.; Beyreuther, K.; Bush, A. I.; Masters, C. L. Soluble pool of Aβ
amyloid as a determinant of severity of neurodegeneration in Alzhei-
mer's disease. Ann. Neurol. 1999, 46, 860–866.
(7) Nelson, P. T.; Braak, H.; Markesbery, W. R. Neuropathology and
cognitive impairment in Alzheimer disease: A complex but coherent
relationship. J. Neuropathol. Exp. Neurol. 2009, 68, 1–14.
(8) N€aslund, J.; Haroutunian, V.; Mohs, R.; Davis, K. L.; Davies, P.;
Greengard, P.; Buxbaum, J. D. Correlation between elevated levels of
amyloid β-peptide in the brain and cognitive decline. J. Am. Med. Assoc.
2000, 283, 1571–1577.
(9) Sorrentino, G.; Bonavita, V. Neurodegeneration and Alzheimer's
disease: The lesson from tauopathies. J. Neurol. Sci. 2007, 28, 63–71.
(10) Skovronsky, D. M.; Lee, V. M.; Trojanowski, J. Q. Neurode-
generative Diseases: New concepts of pathogenesis and their therapeutic
implications. Annu. Rev. Pathol.: Mech. Dis. 2006, 1, 151–170.
(11) Mathis, C. A.; Wang, Y.; Klunk, W. E. Imaging β-amyloid
plaques and neurofibrillary tangles in the aging human brain. Curr.
Pharm. Des. 2004, 10, 1469–1492.
Determination of the Partition Coefficient. The partition
coefficients for these radiolabeled compounds were determined as
described previously but with some modifications.41 The radiola-
beled compound (10 μCi) was added to a premixed suspensions
containing 3 g of n-octanol and 3 g of PBS (0.05 M, pH = 7.4) in a test
tube. The test tube was vortexed for 3 min at room temperature and
centrifuged for 5 min at 3000 rpm. Two weighted samples from the
n-octanol (100 μL) and buffer (500 μL) layers were measured. The
partition coefficient was expressed as the logarithm of the ratio of
the count per gram from n-octanol versus PBS. Samples from the
n-octanol layer were repartitioned until consistent partition coeffi-
cient values were obtained. The measurement was done in triplicate
and repeated three times.
’ ASSOCIATED CONTENT
(12) Cai, L. S.; Innis, R. B.; Pike, V. W. Radioligand development for
PET imaging of β-amyloid (Aβ)-current status. Curr. Med. Chem. 2007,
14, 19–52.
(13) Mathis, C. A.; Wang, Y.; Holt, D. P.; Huang, G. F.; Debnath,
M. L.; Klunk, W. E. Synthesis and evaluation of 11C-labeled 6-substituted
2-arylbenzothiazoles as amyloid imaging agents. J. Med. Chem. 2003,
46, 2740–2754.
(14) Klunk, W. E.; Engler, H.; Nordberg, A.; Wang, Y.; Blomqvist,
G.; Holt, D. P.; Bergstrom, M.; Savitcheva, I.; Huang, G. F.; Estrada, S.;
Ausen, B.; Debnath, M. L.; Barletta, J.; Price, J. C.; Sandell, J.; Lopresti,
B. J.; Wall, A.; Koivisto, P.; Antoni, G.; Mathis, C. A.; Langstrom, B.
Imaging brain amyloid in Alzheimer's disease with Pittsburgh Com-
pound-B. Ann. Neurol. 2004, 55, 306–319.
S
Supporting Information. Purity of key target com-
b
pounds together with HPLC chromatograms, 1H NMR spectra
of compounds, and HRMS data of key target compounds. This
material is available free of charge via the Internet at http://pubs.
acs.org.
’ AUTHOR INFORMATION
Corresponding Author
*Tel: þ81-75-753-4608. Fax: þ81-75-753-4568. E-mail: ono@
pharm.kyoto-u.ac.jp (M.O.). Tel: þ81-75-753-4556. Fax: þ81-
75-753-4568. E-mail: hsaji@pharm.kyoto-u.ac.jp (H.S.).
(15) Koole, M.; Lewis, D.; Buckley, C.; Nelissen, N.; Vandenbulcke,
M.; Brooks, D. J.; Vandenberghe, R.; Laere, K. V. Whole-body biodis-
tribution and radiation dosimetry of 18F-GE067: A radioligand for
in vivo brain amyloid imaging. J. Nucl. Med. 2009, 50, 818–822.
(16) Rowe, C. C.; Ackerman, U.; Browne, W.; Mulligan, R.; Pike,
K. L.; O'Keefe, G.; Tochon-Danguy, H.; Chan, G.; Berlangieri, S. U.;
Jones, G.; Dickinson-Rowe, K. L.; Kung, H. F.; Zhang, W.; Kung, M. P.;
Skovronsky, D.; Dyrks, T.; Holl, G.; Krause, S.; Friebe, M.; Lehman,
L.; Lindemann, S.; Dinkelborg, L. M.; Masters, C. L.; Villemagne,
V. L. Imaging of amyloid β in Alzheimer's disease with 18F-BAY94-
9172, a novel PET tracer: proof of mechanism. Lancet Neurol. 2008,
7, 129–135.
(17) Choi, S. R.; Golding, G.; Zhuang, Z. P.; Zhang, W.; Lim, N.;
Hefti, F.; Benedum, T. E.; Kilbourn, M. R.; Skovronsky, D.; Kung, H. F.
Preclinical properties of 18F-AV-45: A PET agent for Aβ plaques in the
brain. J. Nucl. Med. 2009, 50, 1887–1894.
(18) Kung, H. F.; Choi, S. R.; Qu, W. C.; Zhang, W.; Skovronsky, D.
18F stilbenes and styrylpyridines for PET imaging of Aβ plaques in
Alzheimer's disease: A miniperspective. J. Med. Chem. 2010, 53,
933–941.
’ ACKNOWLEDGMENT
This study was supported by a Grant-in-aid for Young Scien-
tists (A) and Exploratory Research from the Ministry of Educa-
tion, Culture, Sports, Science and Technology, Japan. This study
was also supported by the China Scholarship Council (CSC).
’ ABBREVIATIONS USED
AD, Alzheimer's disease; Aβ, β-amyloid; NFTs, neurofibrillary
tangles; PET, positron emission tomography; SPECT, single
photon emission computed tomography;ThT, thioflavin T; CR,
Congo Red; BBB, bloodꢀbrain barrier; SAR, structureꢀactivity
relationship;TBDMSCl, tert-butyldimethylsilyl chloride; BOC,
butyloxycarbonyl; DMSO, dimethyl sulfoxide; HPLC, high-per-
formance liquid chromatography; THF, tetrahydrofuran;TBAF,
tetra-n-butylammonium fluoride; FPEG, fluoro-pegylated; Tg,
transgenic; IMSB, 1-iodo-2,5-bis(3-hydroxycarbonyl-4-methoxy)
styrylbenzene
(19) Kung, M. P.; Hou, C.; Zhuang, Z. P.; Zhang, B.; Skovronsky, D.;
Trojanowski, J. Q.; Lee, V. M.; Kung, H. F. IMPY: An improved
thioflavin-T derivative for in vivo labeling of β-amyloid plaques. Brain
Res. 2002, 956, 202–210.
(20) Zhuang, Z. P.; Kung, M. P.; Wilson, A.; Lee, C. W.; Plossl, K.;
Hou, C.; Holtzman, D. M.; Kung, H. F. Structure-activity relationship of
imidazo[1,2-a]pyridines as ligands for detecting β-amyloid plaques in
the brain. J. Med. Chem. 2003, 46, 237–243.
’ REFERENCES
(1) Selkoe, D. J. The origins of Alzheimer disease: A is for amyloid.
J. Am. Med. Assoc. 2000, 283, 1615–1617.
(2) Selkoe, D. J. Alzheimer's disease: Genes, proteins, and therapy.
Physiol. Rev. 2001, 81, 741–766.
(3) Hardy, J. A.; Higgins, G. A. Alzheimer's disease: The amyloid
cascade hypothesis. Science 1992, 256, 184–185.
(4) Hardy, J. A.; Selkoe, D. J. The amyloid hypothesis of Alzheimer's
disease: Progress and problems on the road to therapeutics. Science
2002, 297, 353–356.
(21) Newberg, A. B.; Wintering, N. A.; Plossl, K.; Hochold, J.;
Stabin, M. G.; Watson, M.; Skovronsky, D.; Clark, C. M.; Kung,
M. P.; Kung, H. F. Safety, biodistribution, and dosimetry of 123I-IMPY:
A novel amyloid plaque-imaging agent for the diagnosis of Alzheimer's
disease. J. Nucl. Med. 2006, 47, 748–754.
2239
dx.doi.org/10.1021/jm101404k |J. Med. Chem. 2011, 54, 2225–2240

Journal of Medicinal Chemistry
ARTICLE
(22) Qu, W. C.; Kung, M. P.; Hou, C.; Benedum, T. E.; Kung, H. F.
Novel styrylpyridines as probes for SPECT imaging of amyloid plaques.
J. Med. Chem. 2007, 50, 2157–2165.
(23) Watanabe, H.; Ono, M.; Haratake, M.; Kobashi, M.; Saji, H.;
Nakayama, M. Synthesis and characterization of novel phenylindoles as
potential probes for imaging of β-amyloid plaques in the brain. Bioorg.
Med. Chem. 2010, 18, 4740–4746.
inhibition (I50) of an enzymatic reaction. Biochem. Pharmacol. 1973,
22, 3099–3108.
(41) Wu, C. Y.; Wei, J. J.; Gao, K. Q.; Wang, Y. M. Dibenzothiazoles as
novel amyloid-imaging agents. Bioorg. Med. Chem. 2007, 15, 2789–2796.
(24) Cui, M. C.; Ono, M.; Kimura, H.; Kawashima, H.; Liu, B. L.;
Saji, H. Radioiodinated benzimidazole derivatives as single photon
emission computed tomography probes for imaging of β-amyloid
plaques in Alzheimer's disease. Nucl. Med. Biol. DOI: 10.1016/j.
nucmedbio.2010.09.012.
(25) Lockhart, A.; Ye, L.; Judd, D. B.; Merritt, A. T.; Lowe, P. N.;
Morgenstern, J. L.; Hong, G.; Gee, A. D.; Brown, J. Evidence for the
presence of three distinct binding sites for the thioflavin T class of
Alzheimer's disease PET imaging agents on beta-amyloid peptide fibrils.
J. Biol. Chem. 2005, 280, 7677–7684.
(26) Ono, M.; Yoshida, N.; Ishibashi, K.; Haratake, M.; Arano, Y.;
Mori, H.; Nakayama, M. Radioiodinated flavones for in vivo imaging of
β-amyloid plaques in the brain. J. Med. Chem. 2005, 48, 7253–7260.
(27) Ono, M.; Watanabe, R.; Kawashima, H.; Kawai, T.; Watanabe,
H.; Haratake, M.; Saji, H.; Nakayama, M. 18F-Labeled flavones for in vivo
imaging of β-amyloid plaques in Alzheimer's brains. Bioorg. Med. Chem.
2009, 17, 2069–2076.
(28) Ono, M.; Haratake, M.; Mori, H.; Nakayama, M. Novel
chalcones as probes for in vivo imaging of β-amyloid plaques in
Alzheimer's brains. Bioorg. Med. Chem. 2007, 15, 6802–6809.
(29) Ono, M.; Watanabe, R.; Kawashima, H.; Cheng, Y.; Kimura, H.;
Watanabe, H.; Haratake, M.; Saji, H.; Nakayama, M. Fluoro-pegylated
chalcones as positron emission tomography probes for in vivo imaging of
β-amyloid plaques in Alzheimer's disease. J. Med. Chem. 2009,
52, 6394–6401.
(30) Ono, M.; Maya, Y.; Haratake, M.; Ito, K.; Mori, H.; Nakayama,
M. Aurones serve as probes of β-amyloid plaques in Alzheimer's disease.
Biochem. Biophys. Res. Commun. 2007, 361, 116–121.
(31) Maya, Y.; Ono, M.; Watanabe, H.; Haratake, M.; Saji, H.;
Nakayama, M. Novel radioiodinated aurones as probes for SPECT
imaging of β-amyloid plaques in the brain. Bioconjugate Chem. 2009,
20, 95–101.
(32) Ryu, E. K.; Choe, Y. S.; Lee, K. H.; Choi, Y.; Kim, B. T.
Curcumin and dehydrozingerone derivatives: Synthesis, radiolabeling,
and evaluation for β-amyloid plaque imaging. J. Med. Chem. 2006,
49, 6111–6119.
(33) Price, L. C.; Buescher, R. W. Kinetics of alkaline degradation of
the food pigments curcumin and curcuminoids. J. Food Sci. 2006,
62, 267–269.
(34) Tonnesen, H. H.; Karlsen, J. Studies on curcumin and curcu-
minoid. VI. Kinetics of curcumin degradation in aqueous solution. Z.
Lebensm.-Unters. Forsch. A 1985, 180, 402–404.
(35) Van Der Goot, H. The chemistry and qualitative structure-
activity relationship of curcumin. In Recent development in Curcumin
Pharmacochemistry. Proc. Int. Symp. Curcumin Pharmacochemistry
(ISCP) 1995, 23–33.
(36) Zhang, W.; Kung, M. P.; Oya, S.; Hou, C.; Kung, H. F. 18F-
labeled styrylpyridines as PET agents for amyloid plaque imaging. Nucl.
Med. Biol. 2007, 34, 89–97.
(37) Zhang, W.; Oya, S.; Kung, M. P.; Hou, C.; Maier, D. L.; Kung,
H. F. F-18 polyethyleneglycol stilbenes as PET imaging agents targeting
Aβ aggregates in the brain. Nucl. Med. Biol. 2005, 32, 799–809.
(38) Stephenson, K. A.; Chandra, R.; Zhuang, Z. P.; Hou, C.; Oya, S.;
Kung, M. P.; Kung, H. F. Fluoro-pegylated (FPEG) imaging agents
targeting Aβ aggregates. Bioconjugate Chem. 2007, 18, 238–246.
(39) Zhuang, Z. P.; Kung, M. P.; Hou, C.; Skovronsky, D. M.; Gur,
T. L.; Plossl, K.; Trojanowski, J. Q.; Lee, V. M. Y.; Kung, H. F.
Radioiodinated styrylbenzenes and thioflavins as probes for amyloid
aggregates. J. Med. Chem. 2001, 44, 1905–1914.
(40) Cheng, Y.; Prusoff, W. Relationship between the inhibition
constant (Ki) and the concentration of inhibitor which causes 50%
2240
dx.doi.org/10.1021/jm101404k |J. Med. Chem. 2011, 54, 2225–2240