CD4 mimics as HIV entry inhibitors: Lead optimization studies of the aromatic substituents

Article abstract of DOI:10.1016/j.bmc.2013.02.041

Several CD4 mimics have been reported as HIV-1 entry inhibitors that can intervene in the interaction between a viral envelope glycoprotein gp120 and a cell surface protein CD4. Our previous SAR studies led to a finding of a highly potent analogue 3 with bulky hydrophobic groups on a piperidine moiety. In the present study, the aromatic ring of 3 was modified systematically in an attempt to improve its antiviral activity and CD4 mimicry which induces the conformational changes in gp120 that can render the envelope more sensitive to neutralizing antibodies. Biological assays of the synthetic compounds revealed that the introduction of a fluorine group as a meta-substituent of the aromatic ring caused an increase of anti-HIV activity and an enhancement of a CD4 mimicry, and led to a novel compound 13a that showed twice as potent anti-HIV activity compared to 3 and a substantial increase in a CD4 mimicry even at lower concentrations.

Full text of DOI:10.1016/j.bmc.2013.02.041

Accepted Manuscript
CD4 mimics as HIV entry inhibitors: lead optimization studies of the aromatic
substituents
Tetsuo Narumi, Hiroshi Arai, Kazuhisa Yoshimura, Shigeyoshi Harada, Yuki
Hirota, Nami Ohashi, Chie Hashimoto, Wataru Nomura, Shuzo Matsushita,
Hirokazu Tamamura
PII:
S0968-0896(13)00174-0
DOI:
http://dx.doi.org/10.1016/j.bmc.2013.02.041
BMC 10636
Reference:
To appear in:
Bioorganic & Medicinal Chemistry
Received Date:
Revised Date:
Accepted Date:
22 January 2013
25 February 2013
26 February 2013
Please cite this article as: Narumi, T., Arai, H., Yoshimura, K., Harada, S., Hirota, Y., Ohashi, N., Hashimoto, C.,
Nomura, W., Matsushita, S., Tamamura, H., CD4 mimics as HIV entry inhibitors: lead optimization studies of the
aromatic substituents, Bioorganic & Medicinal Chemistry (2013), doi: http://dx.doi.org/10.1016/j.bmc.2013.02.041
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CD4 mimics as HIV entry inhibitors: lead optimization studies of
the aromatic substituents
Tetsuo Narumia, Hiroshi Araia, Kazuhisa Yoshimurab,c, Shigeyoshi Haradab,c, Yuki Hirotaa, Nami
Ohashia, Chie Hashimotoa, Wataru Nomuraa, Shuzo Matsushitab, and Hirokazu Tamamuraa*
aInstitute of Biomaterials and Bioengineering, Tokyo Medical and Dental University,
Chiyoda-ku, Tokyo 101-0062, Japan
bCenter for AIDS Research, Kumamoto University, Kumamoto 860-0811, Japan
cAIDS Research Center, National Institute of Infectious Diseases, Shinjuku-ku, Tokyo 162-8640,
Japan
E-mail: tamamura.mr@tmd.ac.jp
RECEIVED DATE (to be automatically inserted after your manuscript is accepted if
required according to the journal that you are submitting your paper to)
*To whom correspondence should be addressed; tamamura.mr@tmd.ac.jp, phone:
+81-3-5280-8036, fax: +81-3-5280-8039

Abstract
Several CD4 mimics have been reported as HIV-1 entry inhibitors that can intervene in the
interaction between a viral envelope glycoprotein gp120 and a cell surface protein CD4. Our
previous SAR studies led to a finding of a highly potent analogue 3 with bulky hydrophobic
groups on a piperidine moiety. In the present study, the aromatic ring of 3 was modified
systematically in an attempt to improve its antiviral activity and CD4 mimicry which induces the
conformational changes in gp120 that can render the envelope more sensitive to neutralizing
antibodies. Biological assays of the synthetic compounds revealed that the introduction of a
fluorine group as a meta-substituent of the aromatic ring caused an increase of anti-HIV activity
and an enhancement of a CD4 mimicry, and led to a novel compound 13a that showed twice as
potent anti-HIV activity compared to 3 and a substantial increase in a CD4 mimicry even at
lower concentrations.
Keywords
CD4 mimicry
conformational change in gp120
HIV entry inhibitor
envelope protein opener

1. Introduction
The first step of HIV entry into host cells is the interaction of a viral envelope glycoprotein gp120
with the cell surface protein CD4.1 Such a viral attachment process is an attractive target for the
development of the drugs to prevent the HIV-1 infection of its target cells.2 Several small molecules
including BMS-806,3 IC-95644 and NBDs5 have been identified that inhibit the viral attachment
process by binding to gp120. Recently, we and others have been exploring the potentials of
NBDs-derived CD4 mimics as a novel class of HIV entry inhibitors (Figure 1).6-8
Figure 1. Structures of NBD-556 (1), YYA-021 (2) and HAR-171 (3)
Small molecular CD4 mimics identified by an HIV syncytium formation assay showed potent cell
fusion and virus cell fusion inhibitory activity against several HIV-1 laboratory and primary isolates.5
Furthermore, the interaction of CD4 mimics with a highly conserved and functionally important
pocket on gp120, known as the “Phe43 cavity”, induces conformational changes in gp120,9 a process
which occurs with unfavorable binding entropy, leading to a favorable enthalpy change similar to
those caused by binding of the soluble CD4 binding to gp120. These unique properties render CD4
mimics valuable not only for the development of entry inhibitors, but which also, when combined
with neutralizing antibodies function as envelope protein openers-putatively, stimulants.10
The structure of the complex formed by NBD-556 (1) bound to the gp120 core from an HIV-1
clade C strain (C1086) was recently determined by X-ray analysis (PDB: 3TGS).11 As expected with
molecular modeling by us8a and others,6a NBD-556 binds with Phe43 cavity with its p-chlorophenyl

ring inserted into the cavity, and in addition multiple contacts were observed, with Trp112, Val255,
Phe382, Ile424, Asn425, Trp427, Gly473, and Val430 of gp120 were observed (Figure 2). However,
no obvious interaction with Arg59 of CD4 was observed, although the salt bridge formation between
Arg59 of CD4 and Asp368 of gp120 is a critical interaction of the viral attachment.12 Based on this
binding model, several potent compounds were recently identified.6c,7
Figure 2. Major interactions between NBD-556 and Phe43 cavity of gp120
Prior to those studies, we performed structure-activity relationship (SAR) studies based on the
modification of the piperidine moiety of CD4 mimics to interact with Val430 and/or Asp368. These
resulted in the discovery of a potent compound 3 which has bulky hydrophobic groups on its
piperidine ring, and shows significant anti-HIV activity and lower cytotoxicity than other known
CD4 mimics.8c Our study of the docking of 3 into the Phe43 cavity of gp120 suggests that the
cyclohexyl group of 3 can interact hydrophobically with the isopropyl group of Val430.
We hypothesized that the optimization of the aromatic ring of 3 would lead to an increase of
antiviral activity and CD4 mimicry, the latter inducing the conformational changes in gp120. Here,
we describe the systematic modification of the aromatic ring of 3 for further optimization to evaluate
substituent effects on anti-HIV activity, cytotoxicity and CD4 mimicry.
2. Results and Discussion

The co-crystal structure of 1 with the gp120 core revealed that the aromatic group of 1 binds to
gp120 by several aromatic-aromatic and hydrophobic interactions (Figure 2). In particular,
hydrophobic space surrounded by the hydrophobic amino acid residues Trp112, Val255, Phe382, and
Ile424 is likely to be affected by substituents at the meta- and para-positions of the aromatic ring,
and consequently we decided to investigate substituents at these positions (Figure 3).
Aromatic group
Piperidine moiety
Oxalamide linker
H
N
O
NH
N
H
Cl
Cl
Cl
Cl
O
A
Me
Br
Cl
F
NH
Me
Me
Me
Me
Cl
F
B
Figure 3. The structures of scaffolds in the design of novel CD4 mimics.
Initially, we selected a chlorine or a methyl group to serve as the para-substituent of the aromatic
group because CD4 mimic compounds such as 1 (NBD-556) with a p-chloro substituent, and
because 3 showed significant anti-HIV activity compared to other substituents. Further, CD4 mimic
structures such as 2 with a p-methyl substituent also showed potent anti-HIV activity and exhibits
lower cytotoxicity than those with the p-chlorophenyl derivatives.8a Next, we chose several halogens
including F, Cl and Br, to be the meta-substituent on the aromatic group since previous SAR studies
revealed that the introduction of an appropriate group with an electron-withdrawing ability at the
meta-position leads to an increase of binding affinity and antiviral activity.6a Furthermore, to
investigate whether electron withdrawal and hydrophobicity of the meta-position are appropriate, the
CD4 mimics with a meta-methyl substituent, which has electron-donating properties and is similar in
size to bromine, were also synthesized. Finally, two piperidine scaffolds (the

2,2,6,6-tetramethylpiperidine A and the dicyclohexylpiperidine B) were combined with these
aromatics via the oxalamide linker.
2.1 Chemistry
The syntheses of novel compounds are depicted in Schemes 1 and 2. Starting from the
appropriate aniline with m- and p-substituents, coupling with ethyl chloroglyoxylate in the presence
of Et3N gave the corresponding amidoesters 6a-c and 7a-c. Subsequently, microwave-assisted
aminolysis13 of 6a-c and 7a-c with commercially available 4-amino-2,2,6,6-tetramethylpiperidines
afforded the desired compounds 8a-c and 9a-c (Scheme 1). A series of CD4 mimics with two
cyclohexyl groups 13a-c and 14a-c were prepared from 2,2,6,6-tetramethylpiperidin-4-one 10 by the
method previously reported,8c with slight modification (Scheme 2). Briefly, treatment of 10 with
cyclohexanone in the presence of ammonium chloride gave a 2,6-substituted piperidin-4-one 11 via
Grob fragmentation followed by intramolecular cyclization.14 Reductive amination with
p-methoxybenzyl amine, acidic treatment with TMSBr/TFA, and oxidative cleavage of
p-methoxybenzyl group with cerium(IV) ammonium nitrates (CAN) furnished the corresponding
4-aminopiperidines (12) with higher yields and less burdensome purifications than the previous
method. Finally, coupling of 12 with the corresponding esters 6a-c and 7a-c under microwave
irradiation provided the desired compounds 13a-c and 14a-c.

Scheme 1. Reagents and conditions: (a) ethyl chloroglyoxylate, Et3N, THF; (b)
4-amino-2,2,6,6-tetramethylpiperidine, Et3N, EtOH, 150 °C, microwave.
Scheme 2. Reagents and conditions: (a) cyclohexanone, NH4Cl, DMSO, 60 °C; (b)
p-methoxybenzylamine, NaBH CN, MeOH, then 1 M TMSBr in TFA; (c) CAN, CH3CN/H2O (v:v
=2:1); (d) 6 or 7, Et3N, EtOH, 1350 °C, microwave.

2.2 Biological evaluation
The anti-HIV activity of the synthetic compounds was evaluated against an R5 primary isolate
YTA strain. IC50 values were determined by the WST-8 method as the concentrations of the
compounds that conferred 50% protection against HIV-1-induced cytopathogenicity in PM1/CCR5
cells. Cytotoxicity of the compounds based on the viability of mock-infected PM1/CCR5 cells was
also evaluated using the WST-8 method. The assay results for compounds 8a-c and 13a-c with a
p-chlorophenyl group are shown in Table 1. The parent compound 1 and compound 8a,6a known as
JRC-II-191, showed significant anti-HIV activities (IC50 of 1 = 0.61 M and IC50 of 8a = 0.32 M).
Compound 8b6a having a m,p-dichlorophenyl group and compound 8c6a (JRC-II-193) having a
p-chloro-m-tolyl group showed moderate anti-HIV activity (IC50 of 8b = 4.1 M and IC50 of 8c = 3.3
M) but their potency was approximately 10-fold lower than that of compound 8a. The cytotoxicity
of 8b and 8c is relatively stronger than that of 8a (CC50 of 8b = 36 M and CC50 of 8c = 38 M).
Compounds 13a-c with hydrophobic cyclohexyl groups in the piperidine moiety showed more
potent anti-HIV activity than the corresponding compounds 8a-c, confirming the contribution of the
bulky hydrophobic group(s) to an increase of antiviral activity. Our lead compound 3 showed
significant anti-HIV activity comparable to that of compound 8a (IC50 = 0.43 M) but, consistent
with previous results, exhibited lower cytotoxicity. In particular, compound 13a with a
m-fluoro-p-chlorophenyl group exhibited the highest anti-HIV activity. The IC50 value of 13a was
0.23 M, whose potency was approximately twice as high as that of compound 3. Notably,
compound 13b with a m,p-dichlorophenyl group showed 7-fold more potent anti-HIV activity than
the corresponding compound 8b. Compound 13c, which has a p-chloro-m-tolyl group, showed
potent anti-HIV activity comparable to that of the corresponding compound 8c and an increase of
cytotoxicity (CC50 = 15 M). We observed a tendency for compounds 13a-c with both hydrophobic
cyclohexyl groups and a m,p-disubstituted phenyl group to exhibit higher cytotoxicity than the
corresponding tetramethyl-type compounds 8a-c. No clear reason for an increase of cytotoxicity in

the m,p-disubstituted phenyl group-containing compounds is apparent.
Table 1. Anti-HIV activity and cytotoxicity of compounds 8a-c and 13a-c containing a
p-chlorophenyl groupa
IC50 ( M)b
YTA48P
CC50 ( M)c
Compd
R
Y
H
0.61
110
1
F
0.32
4.1
94
36
38
8a
8b
8c
A
A
A
Cl
Me
3.3
H
0.43
120
3
F
0.23
0.62
2.6
11
11
15
13a
13b
13c
B
B
B
Cl
Me
aAll data are the mean values from three of more independent experiments.
bIC50 values of the multi-round assay are based on the inhibition of HIV-1-induced cytopathogenicity in
PM1/CCR5 cells.
cCC50 values are based on the reduction of the viability of mock-infected PM1/CCR5 cells.
Assay results for the compounds 9a-c and 14a-c with a p-tolyl group are shown in Table 2. As

expected, replacement of the p-chloro substituent with a p-methyl group resulted in somewhat
reduction of anti-HIV activity. Compound 2, YYA-021 has significant anti-HIV activity (IC50 = 9.0
M) and exhibits the lowest cytotoxicity among all of the compounds tested (CC50 = 260 M). These
results are consistent with our previous SAR studies involving the aromatic ring. Introduction of a
fluorine at the meta-position of the p-tolyl group, e.g. in compound 9a and 14a, improved the
antiviral activity, as observed with 8a and 13a and a similar tendency was observed for compound
9b with a m-chloro-p-tolyl group. In particular, compound 14a with cyclohexyl groups and a
m-fluoro-p-tolyl group showed slightly higher anti-HIV activity than the parent compound 1. Among
the compounds with m-bromo-p-tolyl groups, it was found that compound 9c, with a
2,2,6,6-tetramethylpiperidine group, showed no anti-HIV activity at a concentration below 10 M,
whereas compound 14c with hydrophobic cyclohexyl groups attached to the piperidine moiety,
showed moderate activity (IC50 = 3.2 M), indicating that the hydrophobic modification of piperidine
ring can contribute to an increase in anti-HIV activity.

Table 2. Anti-HIV activity and cytotoxicity of compounds 9a-c and 14a-c containing a p-tolyl groupa
IC50 ( M)b
YTA48P
CC50 ( M)c
Compd
R
Y
H
9.0
260
2
F
2.8
3.2
110
62
9a
9b
9c
A
A
A
Cl
Br
>10
32
F
0.54
91
14a
Cl
Br
6.2
3.2
11
11
14b
14c
B
B
aAll data are the mean values from three of more independent experiments.
bIC50 values of the multi-round assay are based on the inhibition of HIV-1-induced cytopathogenicity in
PM1/CCR5 cells.
cCC50 values are based on the reduction of the viability of mock-infected PM1/CCR5 cells.
All the synthetic compounds were evaluated for their CD4 mimicry on the conformational
changes in gp120 by fluorescence activated cell sorting (FACS) analysis, and the results are shown
in Figure 4. The profile of binding of a CD4-induced (CD4i) monoclonal antibody (4C11) to the

Env-expressing cell surface pretreated with the synthetic compounds was assessed in terms of the
mean fluorescence intensity (MFI). The increase in binding affinity for 4C11 (by the pretreatment
with synthetic compounds) suggests that those compounds can reflect the CD4 mimicry as a
consequence of the conformational changes in gp120. Our previous studies disclosed that the
profiles of the binding to the cell surface pretreated with 1, 2, or 3 were similar to those observed in
pretreatment with soluble CD4, indicating that these compounds offer a significant enhancement of
binding affinity for 4C11.8 As shown in Figure 4, similar results were obtained with those
compounds in this FACS analysis (MFI of 1, 2, and 3 = 34.94, 25.97, and 24.17, respectively). A
notable increase in binding affinity for 4C11 was observed in essentially all the synthetic compounds.
The compounds 8a, 9a, 13a and 14a with a meta-fluorine in the aromatic ring, showed significant
anti-HIV activity, and produced a substantial increase in binding affinity for 4C11. These results
suggested that the introduction of a fluorine group at the meta position of the aromatic ring is
significant not only for the increase of anti-HIV activity, but also for the enhancement of a CD4
mimicry. In particular, a remarkable improvement in binding affinity for 4C11 was observed with
13a (MFI = 51.39) which has 2-fold more potent anti-HIV activity than the lead compound 3
(HAR-171), and is the most active compound in terms of both anti-HIV activity and the CD4
mimicry resulting from the conformational change in gp120. The profiles of pretreatment of the cell
surface with compounds 8b and 13b having a m,p-dichlorophenyl group, compounds 8c and 13c
having a p-chloro-m-tolyl group, and compounds 9b and 14b with a m-chloro-p-tolyl group were
similar to results obtained for 3, suggesting that these compounds produced slightly lower
enhancement compared to those of compounds 8a, 9a, 13a and 14a but significant levels of binding
affinity for 4C11. On the other hand, pretreatment with compounds 9c, which failed to show
significant anti-HIV activity and 14c, which had moderate anti-HIV activity resulted in a slight
decrease of binding affinity for 4C11, suggesting that the introduction of a Br group at the
meta-position of p-tolyl group is not advantageous to a CD4 mimicry, possibly due to the steric

hindrance caused by the two bulky substituents. These results are consistent with previous
observations that a limited size and electron-withdrawing ability of the aromatic substituents are
required for potent anti-HIV activity and CD4 mimicry.8a
Since 13a showed higher CD4 mimicry than the other compounds tested, the effect of the
solution concentration of 13a on the binding affinity for 4C11 was investigated. As shown in Figure
5, pretreatment of the cell surface with a 100 M solution of 13a produced a higher increase in the
binding affinity for 4C11 than pretreatment with the same concentration of compound 3.
Interestingly, the profile pretreated with a 50 M solution of 13a was similar to that with a 100 µM of
compound 3, and even with a 25 µM solution of 13a a potent enhancement of the binding affinity for
4C11 was observed: MFI of 13a at concentrations of 50 M and 25µM = 19.07 and 16.06
respectively. This observation suggests that 13a could serve as a novel lead compound for the
development of envelope protein openers for the use combined with neutralizing antibodies because
of its effectiveness at low concentrations.
The substantial increase in the CD4 mimicry of 13a even at a low concentration is not easily
explained because HAR-171 (3) and 13a would be expected to form the similar binding modes with
gp120. A probable contribution of 13a is suggested by modeling studies docked into the Phe43
cavity in gp120 (3TGS) in which the depth and direction of the aromatic ring of 13a is slightly
different from those in compound 3 (Figure 6), leading to the possible formation of appropriate
interactions with the hydrophobic amino acid residues such as Val255 and Phe382, and therefore
explaining the increased potency observed in the anti-HIV activity and CD4 mimicry of 13a.

Figure 4. FACS analysis of synthetic compounds 8,9,13 and 14.

Figure 5. FACS analysis of 3 and 13a in different concentrations.
Figure 6. The modeled structure of 13a (yellow carbon atoms) in the complex with the Phe43 cavity
in gp120 (3TGS) overlaid with the modeled structure of 3 (green carbon atoms).
3. Conclusion
CD4 mimics are attractive agents not only for the development of a novel class of HIV entry
inhibitors but also as possible cooperating agents for the neutralizing antibodies – i.e. envelope
protein openers. In the present study, a structure-activity relationship study of a series of CD4 mimic

compounds was performed with a view to improving the biological activity of HAR-171 (3), which
was identified in our previous studies as a promising lead compound with anti-HIV activity,
cytotoxicity and CD4 mimicry resulting from the conformational change in gp120. Systematic
modification of the meta- and para- substituents of the aromatic ring of 3 led to some potent
compounds. In particular, 13a, which has a bulky hydrophobic group on its piperidine ring and a
m-fluoro-p-chlorophenyl group, demonstrated 2-fold more potent anti-HIV activity and much higher
CD4 mimicry than 2 following the conformational changes in gp120, although the cytotoxicity of
13a is relatively high. Further structural modification studies of the aromatic ring and the oxalamide
linker to improve pharmaceutical profiles will be the subject of future reports.
4. Experimentals
1H-NMR and 13C-NMR spectra were recorded using a Bruker Avance III spectrometer. Chemical
shifts are reported in (ppm) relative to Me4Si (in CDCl3) as internal standard. Low- and
high-resolution mass spectra were recorded on a Bruker Daltonics microTOF focus in the positive
and negative detection mode. For flash chromatography, silica gel 60 N (Kanto Chemical Co., Inc.)
was employed. Microwave reactions were performed in Biotage Microwave Reaction Kit (sealed
vials) in an InitiatorTM (Biotage). The wattage was automatically adjusted to maintain the desired
temperature for the desired period of time.
4.1. Chemistry
Ethyl 2-((4-chloro-3-fluorophenyl)amino)-2-oxoacetate (6a): To
a
stirred solution of
3-fluoroaniline (1.11 g, 10.0 mmol) in CHCl3 (30.0 mL) was added dropwise N-chlorosuccinimide
(NCS) in CHCl3 (20.0 mL) at 0 °C. The mixture was stirred at 0 °C for 42 h. After the reaction
mixture was concentrated under reduced pressure, the residue was dissolved in Et2O. The mixture
was washed with water, and dried over MgSO4. Concentration under reduced pressure followed by
flash chromatography over silica gel with EtOAc/n-hexane gave 4-chloro-3-fluoroaniline (259.4 g,
18% yield) as crystalline solids. To a stirred solution of the above aniline (259.4 mg, 1.78 mmol) in

THF (8.9 mL) were added at 0 °C ethyl chloroglyoxylate (237.3 µL, 2.14 mmol) and Et3N (296.6 µL,
2.14 mmol). The mixture was stirred at room temperature for 12 h. After the precipitate was filtrated
off, the filtrate solution was concentrated under reduced pressure. The residue was dissolved in
EtOAc, and washed with 1.0 M HCl, saturated NaHCO3 and brine, then dried over MgSO4.
Concentration under reduced pressure to provide the title compound 6a (435.2 mg, 99% yield) as
brown crystals, which was used without further purification.
1H NMR (500 MHz, CDCl3) 1.44 (t, J = 7.50 Hz, 3H), 4.43 (q, J = 7.50 Hz, 2H), 7.24-7.25 (m, 1H),
7.35-7.40 (m, 1H), 7.70-7.75 (m, 1H), 8.93 (br, 1H); 13C NMR (125 MHz, CDCl3) 13.0, 64.1, 108.5
(d, J = 26.3 Hz), 115.9 (d, J = 3.75 Hz), 117.3 (d, J = 18.8 Hz), 130.9 (d, J = 10.0 Hz), 135.9, 153.9,
158.1 (d, J = 246.3 Hz), 160.5; HRMS (ESI), m/z calcd for C10H10ClFNO3 (MH−) 244.0182, found
244.0183.
Ethyl 2-((3,4-dichlorophenyl)amino)-2-oxoacetate (6b): To
a
stirred solution of
3,4-dichloroaniline 4b (1.94 g, 12.0 mmol) in THF (20.0 mL) were added ethyl chloroglyoxylate
(1.11 mL, 10.0 mmol) and Et3N (15.2 mL, 11.0 mmol) at 0 °C. The mixture was stirred at room
temperature for 6 h. After the precipitate was filtrated off, the filtrate solution was concentrated
under reduced pressure. The residue was dissolved in EtOAc, and washed with 1.0 M HCl, saturated
NaHCO3 and brine, then dried over MgSO4. Concentration under reduced pressure to provide the
title compound 6b (1.58 g, 95% yield) as white powder, which was used without further purification.
1H NMR (500 MHz, CDCl3) 1.44 (t, J = 7.00 Hz, 3H), 4.43 (q, J = 7.00 Hz, 2H), 7.44 (d, J = 8.50
Hz, 1H), 7.49-7.51 (m, 1H), 7.87 2.35 (d, J = 2.50 Hz, 1H); 13C NMR (125 MHz, CDCl3) 14.0,
64.0, 119.0, 121.5, 129.0, 130.8, 133.2, 135.7, 153.9, 160.5; HRMS (ESI), m/z calcd for
C10H10Cl2NO3 (MH+) 262.0038, found 262.0031.
Ethyl 2-((4-chloro-3-methylphenyl)amino)-2-oxoacetate (6c): By use of a procedure similar to
that described for the preparation of compound 6b, the aniline 4c (3.34 g, 24.0 mmol) was converted
into the title compound 6c (4.63 g, 96% yield) as white powder.
1H NMR (500 MHz, CDCl3) 1.43 (t, J = 7.00 Hz, 3H), 2.38 (s, 3H), 4.42 (q, J = 7.00 Hz, 2H), 7.33
(d, J = 8.50 Hz, 1H), 7.43-7.46 (m, 1H), 7.51-7.54 (m, 1H), 8.82 (s, 1H); 13C NMR (125 MHz,
CDCl3)
; HRMS (ESI), m/z calcd for C11H13ClNO3
(MH+) 242.0578, found 242.0568.
Ethyl 2-((3-fluoro-4-methylphenyl)amino)-2-oxoacetate (7a): By use of a procedure similar to
that described for the preparation of compound 6b, the aniline 5a (3.00 g, 24.0 mmol) was converted
into the title compound 7a (4.24 g, 94% yield) as white powder.
1H NMR (500 MHz, CDCl3) 1.43 (t, J = 7.20 Hz, 3H), 2.25 (s, 3H), 4.42 (q, J = 6.80 Hz, 2H),
13
7.12-7.21 (m, 2H), 7.48-7.56 (m, 1H), 8.83 (s, 1H); C NMR (125 MHz, CDCl3) 14.2 (2C), 63.8,
107.1 (d, J = 27.5 Hz), 115.0 (d, J = 10.0 Hz), 122.3 (d, J = 17.5 Hz), 131.6 (d, J = 6.25 Hz), 135.3

(d, J = 13.8 Hz), 153.8, 160.8, 161.1 (d, J = 243.8 Hz); HRMS (ESI), m/z calcd for C11H13FNO3
(MH+) 226.0879, found 226.0878.
Ethyl 2-((3-chloro-4-methylphenyl)amino)-2-oxoacetate (7b): By use of a procedure similar to
that described for the preparation of compound 6b, the aniline 5b (3.40 g, 24.0 mmol) was converted
into the title compound 7b (5.19 g, 94% yield) as white powder.
1H NMR (500 MHz, CDCl3) 1.43 (t, J = 7.00 Hz, 3H), 2.35 (s, 3H), 4.42 (q, J = 7.00 Hz, 2H), 7.22
(d, J = 8.50 Hz, 1H), 7.41-7.43 (m, 1H), 7.71 (d, J = 2.00 Hz, 1H), 8.83 (s, 1H); 13C NMR (125 MHz,
CDCl3)
; HRMS (ESI), m/z calcd for C11H13ClNO3
(MH+) 242.0584, found 242.0573.
Ethyl 2-((3-bromo-4-methylphenyl)amino)-2-oxoacetate (7c): By use of a procedure similar to
that described for the preparation of compound 6b, the aniline 5c (4.47 g, 27.0 mmol) was converted
into the title compound 7c (6.24 g, 96% yield) as white powder.
1H NMR (500 MHz, CDCl3) 1.43 (t, J = 7.00 Hz, 3H), 2.38 (s, 3H), 4.42 (q, J = 7.00 Hz, 2H), 7.23
(t, J = 8.50 Hz, 1H), 7.48-7.53 (m, 1H), 7.83-7.90 (m, 1H), 8.80 (s, 1H); 13C NMR (125 MHz,
CDCl3) 14.0, 22.4, 63.9, 118.7, 123.4, 125.0, 131.0, 135.0, 135.2, 153.7, 160.8; HRMS (ESI), m/z
calcd for C11H13BrNO3 (MH+) 286.0079, found 286.0068.
N1-(4-chloro-3-fluorophenyl)-N2-(2,2,6,6-tetramethylpiperidin-4-yl)oxalamide (8a): To
a
solution of compound 6a (70.0 mg, 0.286) in EtOH (2.9 mL) were added Et3N (0.200 mL, 1.45
mmol) and 2,2,6,6-tetramethylpiperidin-4-amine (0.150 mL, 0.870 mmol). The reaction mixture was
stirred for 3 h at 150 °C under microwave irradiation. After being concentrated in vacuo, the residue
was extracted with CHCl3, and washed with saturated NaHCO3 and brine, then dried over MgSO4.
Concentration under reduced pressure to provide the title compound 8a (34.6 mg, 34% yield) as
white powder.
1H NMR (500 MHz, CDCl3) 0.99-1.50 (m, 15H), 1.92 (dd, J = 3.50, 9.00 Hz, 2H), 4.20-4.32 (m,
1H), 7.21-7.25 (m, 1H), 7.34-7.41 (m, 1H), 7.69-7.73 (m 1H), 9.31 (br, 1H); 13C NMR (125 MHz,
CDCl3) 28.4, 34.8, 43.8, 44.5, 51.0, 108.3 (d, J = 26.3 Hz), 115.8 (d, J = 3.75 Hz), 117.1 (d, J =
17.5 Hz), 130.8, 136.2 (d, J = 8.75 Hz), 157.6, 158.1 (d, J = 247.5 Hz), 158.4; HRMS (ESI), m/z
calcd for C17H24ClFN3O2 (MH+) 356,1536, found 356.1548.
N1-(3,4-dichlorophenyl)-N2-(2,2,6,6-tetramethylpiperidin-4-yl)oxalamide (8b): By use of a
procedure similar to that described for the preparation of compound 8a, the compound 6b (261.0 mg,
1.00 mmol) was converted into the title compound 8b (520.0 mg, 70% yield) as white powder.
1H NMR (500 MHz, CDCl3) 1.07 (t, J = 12.0 Hz, 2H), 1.16 (s, 6H), 1.28 (s, 6H), 1.90-1.93 (m, 2H),
4.20-4.32 (m, 1H), 7.26 (m, 1H), 7.40-7.48 (m, 2H), 7.88 (s, 1H), 9.33 (s, 1H); 13C NMR (125 MHz,
CDCl3) 28.5 (2C), 34.9 (2C), 43.8, 44.6 (2C), 50.9 (2C), 119.0, 121.4, 128.7, 130.8, 133.1, 135.8,

157.7, 158.5; HRMS (ESI), m/z calcd for C17H22Cl2N3O2 (MH-) 370.1095, found 370.1105.
N1-(4-chloro-3-methylphenyl)-N2-(2,2,6,6-tetramethylpiperidin-4-yl)oxalamide (8c): By use of a
procedure similar to that described for the preparation of compound 8a, the compound 6c (482.0 mg,
2.00 mmol) was converted into the title compound 8c (364.0 mg, 49% yield) as white powder.
1H NMR (500 MHz, CDCl3) 1.07 (t, J = 12.0 Hz, 2H), 1.15 (s, 6H), 1.28 (s, 6H), 1.86-1.94 (m, 2H),
4.15-4.31 (m, 1H), 7.21-7.24 (m, 1H), 7.32-7.38 (m, 2H), 7.74 (s, 1H), 9.24 (s, 1H); 13C NMR (125
MHz, CDCl3) 19.6, 28.5 (2C), 34.9 (2C), 43.7, 44.7 (2C), 50.9 (2C), 117.9, 120.2, 131.2, 133.1,
134.7, 135.1, 157.5, 158.8; HRMS (ESI), m/z calcd for C18H25ClN3O2 (MH-) 350.1641, found
350.1656.
N1-(3-fluoro-4-methylphenyl)-N2-(2,2,6,6-tetramethylpiperidin-4-yl)oxalamide (9a): By use of a
procedure similar to that described for the preparation of compound 8a, the compound 7a (225.0 mg,
1.00 mmol) was converted into the title compound 9a (161.0 mg, 48% yield) as white powder.
1H NMR (500 MHz, CDCl3) 1.07 (t, J = 12.5 Hz, 2H), 1.15 (s, 6H), 1.28 (s, 6H), 1.92 (dd, J = 12.5,
3.50 Hz, 2H), 2.26 (s, 3H), 4.12-4.32 (m, 1H), 7.12-7.20 (m, 2H), 7.30-7.37 (m, 1H), 7.48-7.54 (m,
1H), 9.27 (s, 1H); 13C NMR (125 MHz, CDCl3) 14.2, 28.5 (2C), 34.9 (2C), 43.7, 44.7 (2C), 50.9
(2C), 107.1 (d, J = 26.3 Hz), 115.0, 121.8, (d, J = 17.5 Hz) 131.6, 135.4(d, J = 15.0 Hz), 157.5,
158.8, 161.1 (d, J = 242.5 Hz); HRMS (ESI), m/z calcd for C18H25FN3O2 (MH-) 334.1936, found
334.1942.
N1-(3-chloro-4-methylphenyl)-N2-(2,2,6,6-tetramethylpiperidin-4-yl)oxalamide (9b): By use of a
procedure similar to that described for the preparation of compound 8a, the compound 7b (482.0 mg,
1.00 mmol) was converted into the title compound 9b (448.0 mg, 48% yield) as white powder.
1H NMR (500 MHz, CDCl3) 1.09 (t, J = 12.5 Hz, 3H), 1.18 (s, 6H), 1.30 (s, 6H), 1.93-1.95 (m, 2H),
2.41 (s, 3H), 4.20-4.34 (m, 1H), 7.30-7.37 (m, 2H), 7.44-7.46 (m, 1H), 7.53 (d, J = 2.50 Hz, 1H),
13
9.25 (s, 1H); C NMR (125 MHz, CDCl3) 20.3, 28.5 (2C), 34.9 (2C), 43.7, 44.7 (2C), 50.9 (2C),
118.5, 122.0, 130.0, 130.7, 134.8, 137.1, 157.5, 158.8; HRMS (ESI), m/z calcd for C18H25ClN3O2
(MH-) 350.1641, found 350.1636.
N1-(3-bromo-4-methylphenyl)-N2-(2,2,6,6-tetramethylpiperidin-4-yl)oxalamide (9c): By use of a
procedure similar to that described for the preparation of compound 8a, the compound 7c (285.0 mg,
1.00 mmol) was converted into the title compound 9c (157.0 mg, 40% yield) as white powder.
1H NMR (500 MHz, CDCl3) 1.07 (t, J = 12.5 Hz, 3H), 1.15 (s, 6H), 1.28 (s, 6H), 1.91 (dd, J = 8.00,
4.00 Hz, 2H), 2.38 (s, 3H), 3.70-3.75 (m, 1H), 7.22 (d, J = 8.50 Hz, 1H), 7.30-7.37 (m, 1H),
7.43-7.45 (m, 1H), 7.90 (d, J = 2.50 Hz, 1H), 9.25 (s, 1H); 13C NMR (125 MHz, CDCl3) 22.4, 28.5
(2C), 34.9 (2C), 43.7, 44.7 (2C), 50.9 (2C), 118.6, 123.4, 125.0, 131.0, 134.9 (2C), 157.5, 158.8;
HRMS (ESI), m/z calcd for C18H25BrN3O2 (M-) 394.1136, found 394.1158.

Amine (12): the compound 11 was prepared according to the reported procedure.14 To a stirred
solution of piridone 11 (247.8 mg, 1.05 mmol) in MeOH (2.10 mL) was added
p-methoxybenzylamine (0.41 mL, 3.15 mmol). After being stirred at room temperature for 23 h,
sodium cyanoborohydride was added and stirred at room temperature for 48 h. The reaction mixture
was poured into saturated NaHCO3 and extracted with EtOAc, then dried over MgSO4. After
concentration under reduced pressure, the residue was treated with 1 M TMS in THF (4.8 mL). The
mixture was stirred at 0℃ for 14 h. Concentration under reduced pressure followed by short
chromatography with CHCl3/MeOH gave the PMB-protected amine. To a solution of the above
amine (584.0 mg, 1.64 mmol) in CH3CN/H2O (13.1 mL, v:v = 2:1) was added CAN (2.74 g, 8.2
mmol). The mixture was stirred at room temperature for 14 h. The reaction mixture was diluted with
0.5 M HCl and washed with CH2Cl2. The water layer was alkalized and extracted with EtOAc, then
dried over Na2SO4. Concentration under reduced pressure followed by flash chromatography over
silica gel with EtOAc-EtOH (4:1) to gave the title compound 12 (175.5 mg, 71% yield) as a yellow
oil.
1H NMR (500 MHz, CDCl3) 1.15-1.85 (m, 24H), 2.95-3.05 (m, 1H); 13C NMR (125 MHz,
CDCl3) 22.2 (2C), 22.8 (2C), 26.2 (2C), 37.3 (2C), 42.3 (2C), 43.6 (2C), 47.0, 53.2 (2C); HRMS
(ESI), m/z calcd for C15H29N2 (MH+) 237.2325, found 237.2321.
N1-((4-chloro-3-fluorophenyl)-N2-(2,6-dicyclohexylpiperidin-4-yl)oxalamide (13a): By use of a
procedure similar to that described for the preparation of compound 8a, the compound 6a (36.8 mg,
0.150 mmol) was converted into the title compound 13a (7.6 mg, 12% yield) as yellow powder.
1H NMR (400 MHz, CDCl3) 0.71-2.28 (m, 24H), 2.03-2.20 (m, 2H), 4.02-4.16 (m, 1H), 7.13-7.18
13
(m, 1H), 7.27-7.33 (m, 1H), 7.62-7.66 (m, 1H), 9.25 (br, 1H); C NMR (125 MHz, CDCl3) 14.1,
22.0 (2C), 22.6 (2C), 25.8 (2C), 29.3, 29.7 (2C), 31.9, 70.5, 108.3 (d, J = 26.3 Hz), 115.8, 117.1 (d, J
= 18.8 Hz), 130.8, 136.2 (d, J = 10.0 Hz), 157.6, 158.1 (d, J = 247.5 Hz), 158.6; HRMS (ESI), m/z
calcd for C23H32ClFN3O2 (MH+) 436.2162, found 436.2156.
N1-(4-chlorophenyl)-N2-(2,6-dicyclohexylpiperidin-4-yl)oxalamide (13b): By use of a procedure
similar to that described for the preparation of compound 8a, the compound 6b (31.3 mg, 0.120
mmol) was converted into the title compound 13b (28.0 mg, 52% yield) as white powder.
1H NMR (400 MHz, CDCl3) 0.96 (t, J = 12.5 Hz, 2H), 1.10-1.84 (br, 20H), 2.05-2.19 (m, 2H),
4.08-4.21 (m, 1H), 7.23-7.33 (br, 1H), 7.39-7.46 (m, 2H), 7.88 (t, J = 1.00 Hz, 1H), 9.34 (s, 1H); 13C
NMR (125 MHz, CDCl3) 14.1, 22.1 (2C), 22.7 (2C), 26.1 (2C), 31.6, 37.2 (2C), 42.6, 43.0, 43.6,
52.6 (2C), 119.0, 121.4, 128.7, 130.8, 133.1, 135.8, 157.7, 158.5; HRMS (ESI), m/z calcd for
C23H32Cl2N3O2 (MH+) 452.1872, found 452.1865.

N1-((4-chloro-3-methylphenyl)-N2-(2,6-dicyclohexylpiperidin-4-yl)oxalamide (13c): By use of a
procedure similar to that described for the preparation of compound 8a, the compound 6c (121.0 mg,
0.500 mmol) was converted into the title compound 13c (15.1 mg, 7% yield) as white powder.
1H NMR (500 MHz, CDCl3) 0.87-1.88 (br, 22H), 2.09-2.20 (m, 2H), 2.38 (s, 3H), 4.09-4.22 (m,
1H), 7.32-7.33 (m, 1H), 7.41-7.43 (m, 1H), 7.51 (d, J = 2.00 Hz, 1H), 7.73 (m, 1H), 9.24 (s, 1H); 13C
NMR (125 MHz, CDCl3) 20.2, 22.1 (2C), 22.7 (2C), 26.0 (2C), 29.7, 37.0, 42.3 (2C), 42.8 (2C),
43.4, 52.9 (2C), 118.4, 122.0, 130.0, 130.6, 134.8, 137.1, 157.5, 158.9; HRMS (ESI), m/z calcd for
C24H35ClN3O2 (MH+) 430.2267, found 430.2264.
N1-(3-fluoro-4-methylphenyl)-N2-(2,6-dicyclohexylpiperidin-4-yl)oxalamide (14a): By use of a
procedure similar to that described for the preparation of compound 8a, the compound 7a (225.0 mg,
1.00 mmol) was converted into the title compound 14a (27.5 mg, 7% yield) as white powder.
1H NMR (500 MHz, CDCl3) 0.971 (t, J = 12.5 Hz, 2H), 1.18-1.86 (m, 20H), 2.13-2.16 (m, 2H),
2.26 (s, 3H), 4.09-4.21 (m, 1H), 7.13-7.18 (m, 2H), 7.33 (d, J = 8.00 Hz, 1H), 7.50-7.53 (m, 1H),
9.27 (s, 1H); 13C NMR (125 MHz, CDCl3) 14.2, 22.2 (2C), 22.8 (2C), 26.1 (2C), 37.2 (2C), 42.2
(2C), 43.3 (2C), 43.5, 52.6 (m, 2C), 107.0 (d, J = 27.5 Hz), 115.0 (d, J = 3.75 Hz), 121.8 (d, J = 17.5
Hz), 131.6 (d, J = 6.25 Hz), 135.4 (d, J = 10.0 Hz), 157.5, 158.9,161.3 (d, J = 242.5 Hz); HRMS
(ESI), m/z calcd for C24H33FN3O2 (M-) 414.2554, found 414.2562.
N1-(3-chloro-4-methylphenyl)-N2-(2,6-dicyclohexylpiperidin-4-yl)oxalamide (14b): By use of a
procedure similar to that described for the preparation of compound 8a, the compound 7b (120.5 mg,
0.500 mmol) was converted into the title compound 14b (12.9 mg, 6% yield) as white powder.
1H NMR (500 MHz, CDCl3) 0.973 (t, J = 12.5 Hz, 2H), 1.18-1.86 (br, 20H), 2.11-2.19 (m, 2H),
2.35 (s, 3H), 4.09-4.21 (m, 1H), 7.20-7.22 (m, 1H), 7.30-7.32 (m, 1H), 7.35-7.37 (d, J = 2.50 Hz,
1H), 7.73 (m, 1H), 9.22 (s, 1H); 13C NMR (125 MHz, CDCl3) 19.6, 22.1 (2C), 22.7 (2C), 26.0 (2C),
29.7, 37.0, 42.1 (2C), 42.7 (2C), 43.2, 53.3 (2C), 118.0, 120.3, 131.2, 133.0, 134.7, 135.1, 157.5,
158.8; HRMS (ESI), m/z calcd for C24H33ClN3O2 (MH+) 430.2267, found 430.2257.
N1-(3-bromo-4-methylphenyl)-N2-(2,6-dicyclohexylpiperidin-4-yl)oxalamide (14c): By use of a
procedure similar to that described for the preparation of compound 8a, the compound 7c (142.0 mg,
0.500 mmol) was converted into the title compound 14c (11.5 mg, 5% yield) as white powder.
1H NMR (500 MHz, CDCl3) 0.67-2.07 (br, 22H), 2.28 (br, 2H), 2.38 (s, 3H), 4.09-4.21 (m, 1H),
7.22 (d, J = 8.00 Hz, 1H), 7.28-7.38 (br, 1H), 7.43 (dd, J = 4.50, 2.50 Hz, 1H), 7.90 (d, J = 2.50 Hz,
13
1H), 9.21 (s, 1H); C NMR (125 MHz, CDCl3) 14.1, 22.1 (2C), 22.4 (2C), 22.7 (2C), 25.9, 30.0,
31.6, 36.9 (2C), 42.7 (3C), 52.7, 52.9, 118.6, 123.4, 125.0, 131.0, 134.9, 135.1, 157.4, 158.8; HRMS
(ESI), m/z calcd for C24H33BrN3O2 (MH+) 474.1762, found 474.1746.
4.2 Antiviral assay and cytotoxicity assay

Anti-HIV activity and cytotoxicity measurements in PM1/CCR5 cells (Yoshimura et al.,
2010) were based on viability of cells that had been infected or not infected with 100 TCID50 of an
R5 primary isolate YTA48P exposed to various concentrations of the test compound. After the
PM1/CCR5 cells were incubated at 37 ºC for 7 days. The 50% inhibitory concentration (IC50) values
and the 50% cytotoxic concentration (CC50) were then determined using the Cell Counting Kit-8
assay (Dojindo Laboratories). All assays were performed in duplicate or triplicate.
4.3 FACS analysis
JR-FL (R5, Sub B) chronically infected PM1 cells were pre-incubated with 0.5 µg/mL of
sCD4 or 100 M of a CD4 mimic for 15 min, and then incubated with an anti-HIV-1 mAb, 4C11, at
4 °C for 15 min. The cells were washed with PBS, and fluorescein isothiocyanate (FITC)-conjugated
mouse anti-human IgG antibody was used for antibody-staining. Flow cytometry data for the
binding of 4C11 (green lines) to the Env-expressing cell surface in the presence of a CD4 mimic are
shown among gated PM1 cells along with a control antibody (anti-human CD19: black lines). Data
are representative of the results from a minimum of two independent experiments. The number at the
bottom of each graph shows the mean fluorescence intensity (MFI) of the antibody 4C11.
4.4. Molecular modeling
Dockings of compounds 3 and 13a were performed using Molecular Operating
Environment modeling package (MOE 2008. 10, Canada), into the crystal structure of gp120 (PDB,
entry 3TGS).
Supplementary data
Supplementary data (NMR charts of compounds) associated with this article can be found, in
the online version, at doi: .bmc.
.

Acknowledgements
This work was supported in part by Grant-in-Aid for Scientific Research from the Ministry
of Education, Culture, Sports, Science, and Technology of Japan, and Health and Labour Sciences
Research Grants from Japanese Ministry of Health, Labor, and Welfare. We are grateful to Prof.
Yoshio Hayashi and Dr. Fumika Yakushiji, Tokyo University of Pharmacy and Life Sciences for
their assistance in the molecular modelings.

References
1. Chan, D. C.; Kim, P. S. Cell 1998, 93, 681.
2. (a) Kadow, J.; Wang, H.-G.; Lin, P.-F. Curr. Opin. Investig. Dugs 2006, 7, 721; (b) Repik, A.;
Clapham, P. R. Structure 2008, 16, 1603.
3. Holz-Smith, S.; Sun, I. C.; Jin, L.; Matthews, T. J.; Lee, K. H.; Chen, C. H. Antimicrob. Agents
Chemother. 2001, 45, 60.
4. Lin, P.-F.; Blair, W.; Wang, T.; Spicer, T.; Guo, Q.; Zhou, N.; Gong, Y.-F.; Wang, H.-F. H.;
Rose, R., Yamanaka, G.; Robinson, B.; Li, C.-B.; Fridell, R.; Deminie, C.; Demers, G.; Yang,
Z.; Zadjura, L.; Meanwell, N.; Colonno, R. Proc. Natl Acad. Sci. USA. 2003, 100, 11013.
5. Zhao, Q.; Ma, L.; Jiang, S.; Lu, H.; Liu, S.; He, Y.; Strick, N.; Neamati, N.; Debnath, A. K.
Virology 2005, 339, 213.
6. (a) Madani, N.; Schön, A.; Princiotto, A. M.; LaLonde, J. M.; Courter, J. R.; Soeta, T.; Ng, D.;
Wang, L.; Brower, E. T.; Xiang, S.-H.; Do Kwon, Y.; Huang, C.-C.; Wyatt, R.; Kwong, P. D.;
Freire, E.; Smith, A. B., 3rd; Sodroski, J. Structure 2008, 16, 1689; (b) LaLonde, J. M.; Elban,
M. A.; Courter, J. R.; Sugawara, A.; Soeta, T.; Madani, N.; Princiotto, A. M.; Kwon, Y. D.;
Kwong, P. D.; Schön, A.; Freire, E.; Sodroski, J.; Smith, A. B., 3rd, Bioorg. Med. Chem. Lett.,
2011, 20, 354: (c) LaLonde, J. M.; Kwon, Y. D.; Jones, D. M.; Sun, A. W.; Courter, J. R.; Soeta,
T.; Kobayashi, T.; Princiotto, A. M.; Wu, X.; Schön, A.; Freire, E.; Kwong, P. D.; Mascola, J.
R.; Sodroski, J.; Madani, N.; Smith, A. B., 3rd, J. Med. Chem. 2012, 55, 4382.
7. Curreli, F.; Choudhury, S.; Pyatkin, I.; Zagorodnikov, V. P.; Bulay, A. K.; Altieri, A.; Kwon, Y.
D.; Kwon, P. D.; Debnath, A. K. J. Med. Chem. 2012, 55, 4764.
8. (a) Yamada, Y.; Ochiai, C.; Yoshimura, K.; Tanaka, T.; Ohashi, N.; Narumi, T.; Nomura, W.;
Harada, S.; Matsushita, S.; Tamamura, H. Bioorg. Med. Chem. Lett. 2010, 20, 354; (b) Narumi,
T.; Ochiai, C.; Yoshimura, K.; Harada, S.; Tanaka, T.; Nomura, W.; Arai, H.; Ozaki, T.; Ohashi,
N.; Matsushita, S.; Tamamura, H. Bioorg. Med. Chem. Lett. 2010, 20, 5853; (c) Narumi, T.;
Arai, H.; Yoshimura, K.; Harada, S.; Nomura, W.; Matsushita, S.; Tamamura, H. Bioorg. Med.
Chem. 2011, 19, 6735.

9. (a) Schön, A.; Madani, N.; Klein, J. C.; Hubicki, A.; Ng, D.; Yang, X; Smith, A. B., 3rd;
Sodroski, J.; Freire, E. Biochemistry 2006, 45, 10973; (b) Schön, A.; Lam, S. Y.; Freire, E.
Future Med. Chem. 2011, 3, 1129.
10. Yoshimura, K.; Harada, S.; Shibata, J.; Hatada, M.; Yamada, Y.; Ochiai, C.; Tamamura, H.;
Matsushita, S. J. Virol. 2010, 84, 7558.
11. Kwon, Y. D.; Finzi, A.; Wu, X.; Dogo-Isonagie, C.; Lee, L. K.; Moore, L. R.; Schmidt, S. D.;
Stuckey, J.; Yang, Y.; Zhou, T.; Zhu, J.; Vicic, D. A.; Debnath, A. K.; Shapiro, L.; Bewley, C.
A.; Mascola, J. R.; Sodroski, J. G.; Kwong, P. D. Proc. Natl. Acad. Sci. U.S.A. 2012, 109, 5663.
12. (a) Kwong, P. D.; Wyatt, R.; Robinson, J.; Sweet, R. W.; Sodroski, J.; Hendrickson, W. A.
Nature, 1998, 393, 648; (b) Kwong, P. D.; Wyatt, R.; Mcajeed, S.; Robinson, J.; Sweet, R. W.;
Sodroski, J.; Hendrickson, W. A. Structure 2000, 8, 1329.
13. McFarland, C.; Vicic, D. A.; Debnath, A. K. Synthesis 2006, 807.
14. Sakai, K.; Yamada, K.; Yamasaki, T.; Kinoshita, Y.; Mito, F.; Utsumi, H. Tetrahedron 2010, 66,
2311.

CD4 mimics as HIV entry inhibitors: lead optimization studies of the
aromatic substituents
Tetsuo Narumia, Hiroshi Araia, Kazuhisa Yoshimurab,c, Shigeyoshi Haradab,c, Yuki Hirotaa, Nami
Ohashia, Chie Hashimotoa, Wataru Nomuraa, Shuzo Matsushitab, and Hirokazu Tamamuraa*