Physicochemical property-driven optimization of diarylaniline compounds as potent HIV-1 non-nucleoside reverse transcriptase inhibitors

Article abstract of DOI:10.1016/j.bmcl.2014.07.011

Using physicochemical property-driven optimization, twelve new diarylaniline compounds (DAANs) (7a-h, 11a-b and 12a-b) were designed and synthesized. Among them, compounds 12a-b not only showed high potency (EC ₅₀ 0.96-4.92 nM) against both wil

Full text of DOI:10.1016/j.bmcl.2014.07.011

Bioorganic & Medicinal Chemistry Letters 24 (2014) 3719–3723
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Physicochemical property-driven optimization of diarylaniline
compounds as potent HIV-1 non-nucleoside reverse transcriptase
inhibitors
a,
Na Liu a, Bingjie Qin a, Lian-Qi Sun a, Fei Yu b,c, Lu Lu b, Shibo Jiang b,c, Kuo-Hsiung Lee d,e, , Lan Xie
⇑
⇑
a Beijing Institute of Pharmacology & Toxicology, 27 Tai-Ping Road, Beijing 100850, China
b Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Shanghai Medical College and Institute of Medical Microbiology, Fudan University,
Shanghai 200032, China
c Lindsley F. Kimball Research Institute, New York Blood Center, NY 10065, USA
d Natural Products Research Laboratories, UNC Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599-7568, USA
e Chinese Medicine Research and Development Center, China Medical University and Hospital, Taichung, Taiwan
a r t i c l e i n f o
a b s t r a c t
Article history:
Using physicochemical property-driven optimization, twelve new diarylaniline compounds (DAANs)
(7a–h, 11a–b and 12a–b) were designed and synthesized. Among them, compounds 12a–b not only
showed high potency (EC50 0.96–4.92 nM) against both wild-type and drug-resistant viral strains with
the lowest fold change (FC 0.91 and 5.13), but also displayed acceptable drug-like properties based on
aqueous solubility and lipophilicity (LE > 0.3, LLE > 5, LELP < 10). The correlations between potency and
physicochemical properties of these DAAN analogues are also described. Compounds 12a–b merit further
development as potent clinical trial candidates against AIDS.
Received 25 April 2014
Revised 30 June 2014
Accepted 4 July 2014
Available online 11 July 2014
Keywords:
Anti-HIV agents
Diarylaniline
Ó 2014 Elsevier Ltd. All rights reserved.
NNRTIs
Physicochemical property
Non-nucleoside reverse transcriptase inhibitors (NNRTIs) with
diverse structures are a key component of antiretroviral therapy
(ART) for HIV infection and AIDS, because they exhibit high efficacy
and low toxicity, as well as synergistic activity in combination with
other anti-HIV drugs.1,2 Two new-generation NNRTIs, etravirine
(TMC125, 1a) and rilpivirine (TMC278, 1b) (Fig. 1), which were
recently approved by the FDA for anti-AIDS therapy, have much
better potency and pharmacological profiles than early NNRTIs,
such as nevirapine, delavirdine, and efavirenz, and can efficiently
inhibit a broad spectrum of drug-resistant viral strains.3 However,
clinical trials revealed novel resistance mutations4 conferred
against drugs 1a and 1b, which are both diarylpyrimidine (DAPY)
compounds, similar to the early NNRTIs. However, these newly
produced resistance mutations differ from those affecting the early
NNRTIs and from each other, suggesting that a subtle structural
difference between the drugs was sufficient to cause the occur-
rence of distinct HIV mutations. This discovery underscores the
necessity for developing new NNRTI drugs with diverse scaffolds
in order to provide more choices for AIDS treatment and overcome
new resistance mutants. Accordingly, a number of new-generation
NNRTI agents with diverse structures have been discovered5 and
are currently undergoing preclinical and clinical trials.
In our prior studies, several diarylanilines (DAANs) were identi-
fied as novel class of HIV-1 non-nucleoside reverse transcriptase
inhibitor (NNRTI) agents with low nanomolar anti-HIV potency
against wild-type and mutated viral strains,6,7 both comparable
to and better than new-generation NNRTI drugs 1a and 1b. These
DAANs are shown in Figure 1 as leads 2a and 2b. However, their
poor aqueous solubility (<1 lg/mL) resulted in very low absorption
in vivo. To improve molecular aqueous solubility, several polar
groups,8,9 including carboxyl, ester, amide, hydroxyl, and CF3, were
introduced at the R1 group on the central phenyl ring, a point
known to be modifiable for anti-HIV potency, while also associated
with molecular physicochemical properties. These efforts led to the
discovery of hydroxymethyl-DAAN 2c (Fig. 1) with high potency
against wild-type and multi drug-resistant viral strains (EC50
0.53 nM and 0.4 nM, respectively) and improved aqueous solubil-
ity of 3.23 lg/mL at pH 7.4 and 20.9 lg/mL at pH 2.0. Unfortu-
nately, 2c displayed low oral bioavailability (F% 6.10) in
pharmacokinetics assays in vivo. Herein, we have again modified
the DAAN compounds to identify potential drug candidates with
⇑
Corresponding authors. Tel.: +1 919 962 0066; fax: +1 919 966 3893 (K.-H.L.);
tel./fax: +86 10 66931690 (L.X.).
E-mail addresses: khlee@unc.edu (K.-H. Lee), lanxie4@gmail.com (L. Xie).
http://dx.doi.org/10.1016/j.bmcl.2014.07.011
0960-894X/Ó 2014 Elsevier Ltd. All rights reserved.

3720
N. Liu et al. / Bioorg. Med. Chem. Lett. 24 (2014) 3719–3723
CN
CN
CN
NH
CN
NH
O
N
HN
N
N
Br
N
NH2
1b
1a
rilpivirine (TMC278)
etravirine (TMC125)
R2
C
CN
A
New DAANs:
EC50 (nM)
NL4-3 RTMDR1 2.0
WS (ug/mL)
R2 = CN
optimization
7
7.0 F%
R2 = (E)-CH=CHCN
O
NH
11
2a
2b
2c
3.00
0.33
0.53
ND
0.87
0.36
0.42 0.47 ND
0.29 0.29 ND
20.9 3.23 6.1
12 R2 = CH2CH2CN
B
R1
NH2
DAANs
2a R1 = NO2, R2 = CN;
1 = NO2, R2 = (E)-CH=CHCN
2b
2c
R
R
1 = CH2OH, R2 = (E)-CH=CHCN
Figure 1. Next-generation NNRTI drugs, diarylaniline leads (DAANs), and new DAAN analogues.
balanced potency and a desirable absorption, distribution, metab-
olism, and excretion (ADME) profile.
chloride (BiCl3) to afford the corresponding alkoxymethyl-DAAN
compounds 6f and 6g. Furthermore, the hydroxyl group in 6a
was esterified with acetic anhydride to yield compound 6h. Finally,
the nitro group on the central ring of 6a–h was reduced via cata-
lytic hydrogenation in the presence of Pd–C (10%) in either EtOAc
or anhydrous ethanol to furnish new DAAN compounds 7a–h.
The structures of these new DAAN compounds were identified
from proton NMR and MS spectra.15
To explore the correlations between potency and physicochem-
ical properties associated with ADME profile, we continued to
focus on the R1 substituent on the central phenyl ring. In our newly
designed series of DAAN analogues (7a–h, 11a–b, and 12a–b), R1
was altered to alkylamines or alkoxyethers with different shapes,
lengths or volumes. After anti-HIV evaluations, the new active
DAAN compounds were further assessed for multiple physico-
chemical properties, including aqueous solubility and lipophilicity,
as estimated by logP. Apart from aqueous solubility, lipophilicity is
another major physicochemical property that contributes to
potency, affects compound solubility, determines the passive per-
meability of small molecules through biological membranes,
impacts drug metabolism and pharmacokinetics, and influences
adverse effects and compound-related toxicity. Most recently,
new lipophilic parameters, that is, lipophilic efficiency (LE), lipo-
philic ligand efficiency (LLE),10 and ligand-efficiency-dependent
lipophilicity (LELP),11 have been proposed and applied in many
medicinal chemistry programs12–14 to efficiently guide lead opti-
mization. Herein, the synthesis, anti-HIV potency, and assessments
of multiple physicochemical properties of three series of new
DAAN compounds (7a–h, 11a–b, and 12a–b) are reported. The
results will be helpful in guiding our further lead optimization
aimed at the discovery of new clinical trial candidates as potent
anti-AIDS drugs.
Newly synthesized DAAN compounds 7a–h were initially eval-
uated against wild-type HIV-1 (IIIB) replication in MT-2 cells in
parallel with drug 1b. The data are presented in Table 1. As
expected, most new DAANs, except 7e with a bulky N-methylpip-
erazinyl group at the R1 position (EC50 170 nM), exhibited low
nanomolar potency with EC50 values ranging from 1.06 to 14 nM
and high selective index (SI) values of 1142–114,019. The new
7-series compounds were also evaluated against K103N/Y181C
mutant-derived, NNRTI-resistant viral strain A17. However, their
potencies against the wild-type viral strain were clearly reduced,
as demonstrated by EC50 values of greater than 33–2000 nM.
Based on previous SAR results,9 we then designed and synthe-
sized two pairs of compounds 11a–b and 12a–b with a para-cyano-
vinyl and para-cyanoethyl (R2) group, respectively, on the phenoxy
ring (C-ring), as shown in Scheme 2. Similarly to the preparation of
7g and 7h, methoxymethyl-DAAN 9 and acetoxymethyl-DAAN 10
were synthesized from N1-(4-cyanophenyl)-5-(40-cyanovinyl-
20,60-dimethylphenoxy)-4-hydroxymethyl-2-nitroaniline (8).9 Sub-
sequently, the nitro group in 9 and 10 was reduced with iron
powder in the presence of NH4Cl to afford corresponding
para-cyanovinyl-DAAN compounds 11a and 11b,15 respectively,
while the nitro group (R1) and the conjugated double bond in the
cyanovinyl group (R2) of 9 and 10 were reduced simultaneously
using catalytic hydrogenation with Pd/C to produce para-
cyanoethyl-DAAN compounds 12a and 12b.15 The two pairs of
compounds, 11a–b and 12a–b, exhibited high potency against
wild-type HIV-1 replication with sub- to low nanomolar EC50
values ranging from 0.83 to 5.74 nM, and were as or more potent
than 7g and 7h, regardless of whether R2 was p-cyanovinyl or
p-cyanoethyl. More importantly, compounds 12a–b showed high
potency against resistant viral strain A17. Specifically, cyano-
ethyl-DAAN 12a (EC50 2.95 nM) was more potent than cyanovi-
nyl-DAAN 11a (14.7 nM), while both were more potent than
As shown in Scheme 1, target DAAN compounds 7a–h were pre-
pared through a short synthetic route, starting from commercially
available 4-hydroxy-3,5-dimethylbenzonitrile (3). The previously
synthesized
intermediate
5-chloro-N1-(4-cyanophenyl)-4-
methoxycarbonyl-2-nitroaniline (4)8 was coupled with 3 in the
presence of potassium carbonate in DMF under 120 °C for 6 h to
afford 2,4-diarylnitrobenzene 5. By using lithium borohydride
(LiBH4), the ester group on the central phenyl ring in 5 was reduced
to a hydroxymethyl group in the key intermediate 6a. Subse-
quently, 6a was treated with 2,4,6-trichloro-[1,3,5]triazine
followed by nucleophilic substitution with methylamine, cyclopro-
panamine, 3-aminopropan-1-ol, or 1-methyl-piperazine to pro-
duce the corresponding compounds 6b–e, respectively, with
different alkylamines at the R1 position. Alternatively, 6a was
reacted with isopropanol or methanol in the presence of bismuth

N. Liu et al. / Bioorg. Med. Chem. Lett. 24 (2014) 3719–3723
3721
CN
CN
CN
O
CN
HO
CN
CN
3
i
ii
+
O
NH
NH
Cl
MeOOC
NH
HO
MeOOC
NO2
NO2
NO2
4
5
6a
vii
CN
O
CN
CN
CN
iii, iv
v
vii
6a
NH
O
NH
vi
X
R1
R
NO2
NH2
7a-h
6b-e, X = N
6f-h,
X = O
Scheme 1. Reagents and conditions: (i) K2CO3/DMF, 120 °C, 6 h; (ii) LiBH4, THF/MeOH, 0 °C, 7 h; (iii) 2,4,6-trichloro-[1,3,5]triazine, DMF/CH2Cl2, rt, 4 h; (iv) amine, THF, 0 °C,
0.5 h; (v) ROH/BiCl3, CH2Cl2/CCl4, rt, 4 h; (vi) Ac2O, 100 °C, Microwave, 5 min; (vii) H2/Pd–C in EtOAc or EtOH.
Table 1
Anti-HIV data of new DAANs against wild-type and resistant viral strainsa
H
R2
O
N
7
R2 = CN
11 R2 = (E)-CH=CHCN
R1
NH2
CN
R
2 = CH2CH2CN
12
R1
EC50 (nM) IIIBb
CC50
(
lM)
SI
EC50 (nM) A17c
FCd
7a
7b
7c
7d
7e
OH
NHMe
1.07 0.25
9.94 1.57
10.6 0.64
6.10 1.10
170 5.60
14.0 1.10
3.54 0.62
1.06 0.01
5.74 2.20
3.25 0.23
0.82 0.07
0.96 0.12
0.49 0.17
122
114,019
1278
1142
2475
570
33.1 4.05
115 3.10 103.5
130 2.87
>2000
30.9
11.6
12.3
>328
>11.8
22.5
84.2
353
12.7
12.1
15.1
96.9
89.4
146
NHCH(CH2)2
NH(CH2)3OH
N(CH2CH2)2NMe
OCHMe2
OMe
OAc
OMe
OMe
OAc
>2000
7f
7g
6386
315 25.7
298 133
374 111
14.7 0.74
2.95 0.50
36.50 1.78
4.92 0.12
9.03 0.74
41,243
106,604
8763
>61,538
117,439
46,667
185,102
7h
11a
12a
11b
12b
1b
113
50.3
>200
96.3
44.8
90.7
2.6
0.91
44.5
5.1
OAc
TMC278
18.4
a
b
c
Experiments performed at least in triplicate in MT-2 cells and data presented as the mean SD.
HIV-1 wild-type virus.
Drug-resistant virus from NIH with mutated K103N and Y181C in the NNRTI binding pocket.
Fold change resistance.
d
cyano-DAAN compound 7g (298 nM). Similar differences in
potency were observed when comparing acetoxymethyl-DAAN
compounds 12b (4.92 nM), 11b (36.5 nM), and 7h (374 nM). These
results clearly demonstrate that the R2 group on the phenoxy ring
(C-ring) directly affects molecular potency against wild-type, as
well as resistant, viral strains. A cyanoethyl group, which is more
flexible due to its linearity, was more favorable than a cyanovinyl
or cyano group. Notably, highly potent 12a and 12b had low fold
change (FC) between A17 and wild-type IIIB virus with FC values
of 0.91 and 5.13, respectively, much lower than that of 1b (FC
18.4) in the same assay.
compounds in stomach and plasma, respectively. As expected,
alkylamine-DAAN compounds 7b, 7c, and 7d displayed greatly
improved solubility at both pH 2.0 (263, 285, and 290
respectively) and pH 7.4 (159, 13, and 236 g/mL, respectively)
compared with drug 1b (pH 2.0, 74 g/mL; pH 7.4, 0.29 g/mL).
lg/mL,
l
l
l
Thus, the introduction of suitable alkylamino groups at the R1
position could greatly improve the molecular aqueous solubility.
Active compounds hydroxymethyl-DAAN 7a (R1 = CH2OH),
methoxymethyl-DAANs 7g, 11a, and 12a (R1 = CH2OMe), and
acetoxymethyl-DAANs 7h, 11b, and 12b (R1 = CH2OAc) also dem-
onstrated improved aqueous solubility at pH 2.0 (1.7–9.10
lg/
Next, several physicochemical properties of newly generated
DAANs (EC50 < 11 nM) (7a–d, 7g–h, 11a–b and 12a–b) and drug
1b were assessed, and the resulting data are summarized in Table 2.
Aqueous solubility was measured by HPLC at pH 2.0 and 7.4 to
reflect the physiological conditions encountered by these
mL), but not at pH 7.4 (<1 g/mL). For oral drug candidates, better
l
aqueous solubility at pH 2.0 is desirable to enhance absorbability
in the stomach.18 Meanwhile, we observed that all 10 new active
compounds had lower melting points than 1b. This difference
might be explained by the assumption that the R1 group on the

3722
N. Liu et al. / Bioorg. Med. Chem. Lett. 24 (2014) 3719–3723
R2
CN
CN
CN
CN
CN
i or ii
iii or iv
O
NH
O
NH
O
NH
R1
NH2
HO
O
11a R1 = OMe, R2 = CH=CHCN
NO2
R
NO2
11b R1 = OAc, R2 = CH=CHCN
8
9 R = Me
10
12a R1 = OMe, R2 = CH2CH2CN
12b R1 = OAc, R2 = CH2CH2CN
R = Ac
Scheme 2. Reagents and conditions: (i) ROH/BiCl3, CH2Cl2/CCl4, rt, 4 h; (ii) Ac2O, 100 °C, Microwave, 5 min; (iii) Fe, NH4Cl, THF/MeOH/H2O, reflux, 3 h; (iv) H2/Pd–C in EtOH.
Table 2
Physicochemical parameters of new active DAAN compounds
Aqueous solubility (
l
g/mL)a
Mp (°C)
LogPb
pH 7.4
clogDc
tPSAd
Lipophilic efficiency indices16,17
(Å2)
LEf
LLEg
LELPh
e
pH 2.0
pH 7.4
pEC50
7a
7b
7c
7d
7g
7h
11a
12a
11b
12b
1b
9.12
263
286
290
3.75
16.7
1.70
1.82
1.87
2.63
86.8
0.86
159
13.0
236
0.07
0.20
0.11
0.66
0.49
1.86
0.24
230–2
202–3
72–3
3.57
1.86
3.84
1.81
3.84
4.40
4.13
3.25
4.48
2.84
>5
3.23
3.72
4.08
3.31
4.16
4.12
4.48
3.87
4.45
3.84
3.62
115.1
106.9
106.9
127.1
104.1
121.2
104.1
104.1
121.2
121.2
97.4
8.97
8.00
7.97
8.21
8.45
8.97
8.24
8.49
9.08
9.02
9.31
0.42
0.37
0.34
0.34
0.39
0.38
0.35
0.36
0.37
0.36
0.46
5.40
6.14
4.13
6.40
4.61
4.57
4.11
5.24
4.60
6.18
5.69i
8.50
5.03
11.30
5.32
9.85
11.60
11.80
9.03
76–8
176–8
161–3
171–2
104–5
194–6
164–6
246–8
12.20
7.92
7.87i
a,b
c
Measured by HPLC in triplicate.
Predicted by ACD software.
Topological polar surface area predicted by ChemDraw Ultra 12.0.
Negative logarithm values of potency converted from experimental data against wild-type virus IIIB shown in Table 1.
d
e
f
Calculated by the formula ꢀG/HA(non-hydrogen atom), in which normalizing binding energy G = ꢀRTlnKd, presuming EC50 ꢁ Kd.
g
h
i
Calculated by the formula pEC50 ꢀlogP.
Defined as a ratio of measured logP and LE.
Data calculated with clogD.
central phenyl ring might disrupt molecular planarity and crystal
packing,19 which could also enhance molecular aqueous solubility.
To estimate molecular lipophilicity, the logP parameters of these
active compounds were measured by HPLC at pH 7.4.9 The exper-
imental logP values fell within an acceptable range of 1.80–4.40,
which is consistent with the measured aqueous solubilities, and
showed the same trend as the clogD values predicted by ACD
software. Additionally, topological polar surface area (tPSA)
parameters of all active compounds were calculated by ChemDraw
Ultra 12.0 and met the criterion20 of <140 Å2 for potential oral drug
candidates.
To estimate the possible ADME profiles and potential of our
drug candidates, we focused next on their lipophilic indices,
including lipophilic efficiency (LE), lipophilic ligand efficiency
(LLE), and ligand-efficiency-dependent lipophilicity (LELP). Defined
as the difference between the negative logarithm of the measured
potency (pEC50) and logP, LLE quantifies the contribution of lipo-
philicity to potency, whereas LELP17 correlates with ADME proper-
ties. Thus, compounds with a low LELP value would most likely
have a high chance of passing all ADME and safety criteria,21 while
compounds with high LELP values (typically >10) would have a
higher propensity to fail because of ADME and safety risks. Accord-
ingly, lipophilic parameters of the new active DAANs were calcu-
lated from their experimental EC50 and logP values by the
formulas cited at the bottom of Table 2. Consequently, compounds
7a, 7b, 7d, 12a, and 12b met acceptable levels for all three ligand
lipophilic-efficiency indices (LE > 0.3, LLE > 5, LELP < 10),21 while
the remaining compounds in Table 2 did not, having either LLE
values lower than 5 or LELP values higher than 10. Among the five
promising compounds, 7b and 7d showed higher aqueous solubil-
ity at different pH conditions as well as lower logP and LELP values
than the other compounds, suggesting better ADME profiles. On
the other hand, the 7 series of DAANs were not efficient against
resistant viral strain A17. Compounds 12a and 12b did show more
balanced potency between the HIV-1 wild-type and resistant viral
strains, as well as met acceptable lipophilic criteria, as determined
by the LE, LLE and LELP indices. However, the aqueous solubility of
both compounds was obviously lower than that of either 7b or 7d.
Thus, to avoid the risk of potential oral absorption, these results
suggested that the 12a–b pair requires additional optimization to
improve aqueous solubility.
In summary, three series of new DAAN compounds (7a–h,
11a–b, and 12a–b) with interchangeable R1 and R2 modification/
optimization were successfully synthesized as part of our ongoing
anti-HIV NNRTI program. Our current physicochemical property-
driven optimization resulted in the discovery of two promising
compounds, 12a and 12b, with high potency against wild-type
and drug-resistant viral strains, low nanomolar EC50 values
(0.96–4.92 nM), low fold change resistance (FC 0.91 and 5.13),
and acceptable lipophilicity, as demonstrated by meeting accept-
able values for all lipophilic parameters (LE > 0.3, LLE > 5,
LELP < 10; logP < 5, tPSA < 140 Å2),21 even though their aqueous
solubility needs further improvement. Optimization of the series
7 compounds revealed that (1) the presence of an alkylamine sub-
stituent at the R1 position can greatly improve molecular aqueous
solubility (see 7b–d) without loss of antiviral potency, (2) a bulky
R1 group can result in substantially impaired antiviral activity (see
7e), and (3) introducing an H-bond acceptor or donor at the R1

N. Liu et al. / Bioorg. Med. Chem. Lett. 24 (2014) 3719–3723
3723
of THF/water/MeOH (v/v/v 1:1:1) for 4 h. Compound 7a: yield 73%, white solid,
mp 230.0–232 °C; 1H NMR (CDCl3) d ppm 2.14 (6H, s, 2ꢂ CH3),4.88 (2H, s, CH2),
5.51 (1H, s, NH) 5.99 (1H, s, ArH-6), 6.54 (2H, d, J = 8.4 Hz, ArH-20,60), 6.97 (1H,
s, ArH-3), 7.40 (2H, s, ArH-300,500), 7.41 (2H, d, J = 8.4 Hz, ArH-30,50); MS m/z (%)
385.2 (M+1, 100). Compound 7b: white solid, mp 201–203 °C; 1H NMR (CDCl3)
d ppm 2.13 (6H, s, 2ꢂ CH3), 2.56 (3H, s, NCH3), 3.58 (2H, s, NH2), 3.95 (2H, s,
ArCH2), 5.51 (1H, s, NH), 5.96 (1H, s, ArH-6), 6.53 (2H, d, J = 8.4 Hz, ArH-20,60),
6.93 (1H, s, ArH-3), 7.38 (2H, s, ArH-300,500), 7.39 (2H, d, J = 8.4 Hz, ArH-30,50);
MS m/z (%) 398.1 (M+1, 1), 358 (Mꢀ30, 100). Compound 7c: yield 83%, white
solid, mp 72.0–73.3 °C; 1H NMR (CDCl3) d ppm 0.49 (4H, m, CH2CH2), 2.14 (6H,
s, 2ꢂ CH3), 2.24 (3H, m, CH), 3.53 (2H, s, NH2), 4.00 (2H, s, ArCH2), 5.48 (1H, s,
NH), 5.96 (1H, s, ArH-6), 6.53 (2H, d, J = 8.8 Hz, ArH-20,60), 6.93 (1H, s, ArH-3),
7.38 (2H, s, ArH-300,500), 7.39 (2H, d, J = 8.8 Hz, ArH-30,50); MS m/z (%) 434.2
(M+1, 3), 367.2 (Mꢀ56, 100). Compound 7d: yield 38%, white solid, mp 76.0–
78.0 °C; 1H NMR (CDCl3) d ppm 1.79 (2H, f, J = 5.6 Hz, CH2), 2.13 (6H, s, 2ꢂ CH3),
3.01 (2H, t, J = 5.6 Hz, NCH2), 3.87 (2H, t, J = 5.6 Hz, CH2O), 3.95 (2H, s, ArCH2),
5.51 (1H, s, NH), 5.96 (1H, s, ArH-6), 6.54 (2H, d, J = 8.8 Hz, ArH-20,60), 6.86 (1H,
s, ArH-3), 7.39 (2H, s, ArH-300,500), 7.41 (2H, d, J = 8.8 Hz, ArH-30,50); MS m/z (%)
442.6 (M+1, 20), 367.2 (Mꢀ74, 100). Compound 7e: yield 40%, white solid, mp
210.2–212.0 °C; 1H NMR (CDCl3) d ppm 2.09 (3H, s, CH3), 2.08 (3H, s, CH3), 2.12
(6H, s, 2ꢂ CH3), 2.78 (4H, t, J = 4.8 Hz, CH2CH2), 3.05 (4H, s, J = 4.8 Hz, CH2CH2),
3.72 (2H, s, ArCH2), 5.87 (1H, s, NH), 6.01 (1H, s, ArH-3), 6.60 (2H, d, J = 8.4 Hz,
ArH-20,60), 7.44 (2H, d, J = 8.4 Hz), 7.69 (2H, s, ArH-300,500), 8.62 (1H, s, ArH-6);
MS m/z (%) 467.6 (M+1, 31), 367.3 (Mꢀ99, 100). Compound 7f: yield 33%, white
solid, mp 140.9–142.9 °C; 1H NMR (CDCl3) d ppm 1.28 (6H, d, J = 6.4 Hz, 2ꢂ
CH3), 2.14 (6H, s, 2ꢂ CH3), 3.81 (1H, q, J = 6.4 Hz, CH), 4,69 (2H, s, ArCH2), 5.53
(1H, s, NH), 5.96 (1H, s, ArH-6), 6.53 (2H, d, J = 8.4 Hz, ArH-20,60), 7.04 (1H, s,
ArH-3), 7.38 (2H, s, ArH-300,500), 7.40 (2H, d, J = 8.4 Hz, ArH-30,50); MS m/z (%)
position (such as 7a–b and 7d–g) might regulate the molecular
lipophilicity to meet desired drug criteria. Our optimization efforts
at the R2 position on the phenoxy ring (C-ring) indicated that a
more flexible and longer linear cyanovinyl (11 series) or, prefera-
bly, cyanoethyl (12 series) substituent, rather than a cyano group
(7 series) is crucial for high potency against both wild-type and
double-mutant drug-resistant viral strains (compare 7g–h, 11a–
b, and 12a–b). Consequently, a number of compounds from this
series are being considered for in vivo pharmacokinetic evaluation,
and the results will be reported later.
Acknowledgments
This investigation was supported by Grants 30930106 and
81120108022 from the Natural Science Foundation of China (NSFC)
to L.X., the National Megaprojects of China for Major Infectious Dis-
eases (2013ZX10001-006) to L.X. and S.J., and U.S. NIH Grant
(AI33066) to K.-H.L. This study was also supported in part by the
Taiwan Department of Health, China Medical University Hospital
Cancer Research Center of Excellence (DOH100-TD-C-111-005).
References and notes
427.4 (M+1, 100). Compound 7g: yield 33%, white solid, mp 140.9–142.9 °C; 1
H
NMR (CDCl3) d ppm 1.28 (6H, d, J = 6.4 Hz, 2ꢂ CH3), 2.14 (6H, s, 2ꢂ CH3), 3.81
(1H, q, J = 6.4 Hz, CH), 4.69 (2H, s, ArCH2), 5.53 (1H, s, NH), 5.96 (1H, s, ArH-6),
6.53 (2H, d, J = 8.4 Hz, ArH-20,60), 7.04 (1H, s, ArH-3), 7.38 (2H, s, ArH-300,500),
7.40 (2H, d, J = 8.4 Hz, ArH-30,50); MS m/z (%) 427.4 (M+1, 100). Compound 7h:
yield 34%, white solid, mp 161.0–162.8 °C; 1H NMR (CDCl3) d ppm 2.14 (9H, s,
2ꢂ CH3, COCH3), 3.55 (2H, s, NH2), 5.29 (2H, s, ArCH2), 5.52 (1H, s, NH), 6.00
(1H, s, ArH-6), 6.56 (2H, d, J = 8.4 Hz, ArH-20,60), 6.94 (1H, s, ArH-3), 7.39 (2H, s,
ArH-300,500), 7.42 (2H, d, J = 8.4 Hz, ArH-30,50); MS m/z (%) 427.5 (M+1, 62), 367
(Mꢀ99, 100). Compound 11a: 50% yield, white solid, mp 170.5–172.0 °C; 1H
NMR (CDCl3) d ppm 2.13 (6H, s, 2ꢂ CH3), 3.54 (5H, s, OCH3, NH2), 4.67 (2H, s,
CH2O), 5.51 (1H, s, NH), 5.79 (1H, d, J = 16.4 Hz, @CH), 6.03 (1H, s, ArH-6), 6.55
(2H, d, J = 8.8 Hz, ArH-20,60), 6.99 (1H, s, ArH-3), 7.17 (2H, s, ArH-300,500), 7.31
(2H, d, J = 16.4 Hz, CH@), 7.40 (2H, d, J = 8.8 Hz, ArH-30,50); MS m/z (%) 425.3
(M+1, 100). Compound 11b: 35% yield, white solid, mp 194.1–195.9 °C; 1H
NMR (CDCl3) d ppm 2.14 (6H, s, 2ꢂ CH3), 2.15 (3H, s, CH3CO), 3.53 (2H, s, NH2),
5.30 (2H, s, ArCH2O), 5.51 (1H, s, NH), 5.78 (1H, d, J = 16.8 Hz, @CH), 6.05 (1H, s,
ArH-6), 6.55 (2H, d, J = 8.8 Hz, ArH-20,60), 6.93 (1H, s, ArH-3), 7.17 (2H, s, ArH-
300,500), 7.30 (1H, d, J = 16.8 Hz, CH@), 7.40 (2H, d, J = 8.8 Hz, ArH-3); MS m/z (%)
393.2 (Mꢀ59, 100), 453.3 (M+1, 97.2). Compound 12a: 79% yield, white solid,
mp 103.6–104.8 °C; 1H NMR (CDCl3) d ppm 2.09 (6H, s, 2ꢂ CH3), 2.61(2H, t,
J = 7.2 Hz, CH2CN), 2.87 (2H, t, J = 7.2 Hz, ArCH2), 3.52 (3H, s, OCH3), 4.67 (2H, s,
CH2O), 5.56 (1H, s, NH), 6.03 (1H, s, ArH-6), 6.55 (2H, d, J = 8.8 Hz, ArH-20,60),
6.92 (2H, s, ArH-300,500), 6.99 (1H, s, ArH-3), 7.39 (2H, d, J = 8.8 Hz, ArH-30,50);
MS m/z (%) 427.3 (M+1, 100). Compound 12b: 40% yield, white solid, mp
164.1–165.7 °C; 1H NMR (DMSO-d6) d ppm 2.04 (6H, s, 2ꢂ CH3), 2.09 (3H, s,
COCH3), 2.78 (4H, s, 2ꢂ CH2), 4.58 (2H, s, NH2), 5.19 (2H, s, CH2O), 5.90 (1H, s,
NH), 6.54 (2H, d, J = 8.8 Hz, ArH-20,60), 6.87 (1H, s, ArH-6), 7.04 (2H, s, ArH-
300500), 7.45 (2H, d, J = 8.8 Hz, ArH-30,50), 8.08 (1H, s, ArH-3); MS m/z (%) 395.2
(Mꢀ59, 100), 455.3 (M+1, 17).
1. Tronchet, J. M.; Seman, M. Curr. Top. Med. Chem. 2003, 3, 1496.
2. Tarby, C. M. Curr. Top. Med. Chem. 2004, 4, 1045.
3. Guillemont, J.; Pasquier, E.; Palandjian, P.; Vemier, D.; Gaurrand, S.; Lewi, P. J.;
Heeres, J.; De Jonge, M. R.; Koymans, L. M. H.; Daeyaert, F. F. D.; Vinkers, M. H.;
Arnold, E.; Das, K.; Pauwels, R.; Andries, K.; De Bethune, M.-P.; Bettens, E.;
Hertogs, K.; Wigerinck, P.; Timmerman, P.; Janssen, P. A. J. Med. Chem. 2005, 48,
2072.
4. Bourgeois, A.; Womack, S.; Newsom, D.; Caldwell, D. HIV Clin. 2012, 24, 12.
5. Rawal, R. K.; Murugesan, V.; Katti, S. B. Curr. Med. Chem. 2012, 19, 5364.
6. Qin, B.; Jiang, X. K.; Lu, H.; Tian, X. T.; Barbault, F.; Huang, L.; Qian, K.; Chen, C.
H.; Huang, R.; Jiang, S.; Lee, K. H.; Xie, L. J. Med. Chem. 2010, 53, 4906.
7. Tian, X. T.; Qin, B.; Wu, Z. Y.; Wang, X. F.; Lu, H.; Morris-Natschke, S. L.; Chen, C.
H.; Jiang, S.; Lee, K. H.; Xie, L. J. Med. Chem. 2010, 53, 8287.
8. Sun, L. Q.; Qin, B.; Huang, L.; Qian, K.; Chen, C. H.; Lee, K. H.; Xie, L. Bioorg. Med.
Chem. Lett. 2012, 22, 2376.
9. Sun, L. Q.; Zhu, L.; Qian, K.; Qin, B.; Huang, L.; Chen, C. H.; Lee, K. H.; Xie, L. J.
Med. Chem. 2012, 55, 7219.
10. Leeson, P. D.; Springthorpe, B. Nat. Rev. Drug Disc. 2007, 6, 881.
11. Keseru, G. M.; Makara, G. M. Nat. Rev. Drug Disc. 2009, 8, 203.
12. Jabeen, I.; Plehab, K.; Rinner, U.; Chibe, P.; Ecker, G. F. J. Med. Chem. 2012, 55,
3261.
13. Christiansen, E.; Due-Hansen, M. E.; Urban, C.; Grundmann, M.; Schroder, R.;
Hudson, B. D.; Milligan, G.; Cawthorne, M. A.; Kostenis, E.; Kassack, M. U.;
Ulven, T. J. Med. Chem. 2012, 55, 6624.
14. Diaz, J. L.; Christmann, U.; Fernandez, A.; Luengo, M.; Bordas, M.; Enrech, R.;
Carro, M.; Pascual, R.; Burgueno, J.; Merlos, M.; Bebet-Buchholz, J.; Ceron-
Bertran, J.; Ramirez, J.; Reinoso, R. F.; de Henestrosa, F. A. R.; Vela, J. M.;
Almansa, C. J. Med. Chem. 2013, 56, 3656.
15. Synthetic procedure for 4-substituted 1,5-diarylbenzene-1,2-diamines (7a–h and
12a–b). A solution of diarylnitrobenzene in 20 mL of anhydrous EtOAc (for 7a–
c and 7e–f) or anhydrous EtOH (for 7d, 7g–h and 12a–b) in the presence of
excess Pd/C (5%) was shaken with hydrogen gas under 50–55 p.s.i. until the
hydrogen was no longer absorbed (ca. 4 h). The catalyst was filtered from the
solution and washed with EtOAc several times. After the solvent was removed
under reduced pressure, the residue was purified by flash column
chromatography (gradual elution: MeOH/CH2Cl2, 0–5%) with the CombiflashÒ
flash chromatography system (Teledyne ISCO Company, Inc., Lincoln, NE) to
obtain pure target compounds 7a–h and 12a–b. Otherwise, para-cyanovinyl-
compounds 11a and 11b were obtained from 9 and 10 by reaction with excess
iron powder in the presence of NH4Cl at reflux temperature in a mixed solvent
16. Ramurthy, S.; Subramanian, S.; Aikawa, M.; Amiri, P.; Costales, A.; Dove, J.;
Fong, S.; Jansen, J. M.; Levine, B.; Ma, S.; McBride, C. M.; Michaelian, J.; Pick, T.;
Poon, D. J.; Girish, S.; Shafer, C. M.; Stuart, D.; Sung, L.; Renhowe, P. A. J. Med.
Chem. 2008, 51, 7049.
17. Ishikawa, M.; Hashimoto, Y. J. Med. Chem. 2011, 54, 1539.
18. Veber, D. F.; Johnson, S. R.; Cheng, H.-Y.; Smith, B. R.; Ward, K. W.; Kopple, K. D.
J. Med. Chem. 2002, 45, 2615.
19. Tarcsay, A.; Nyiri, K.; Keseru, G. M. J. Med. Chem. 2012, 55, 1252.
20. Jabeen, I.; Pleban, K.; Rinner, U.; Chiba, P.; Ecker, G. F. J. Med. Chem. 2012, 55,
3261.
}
21. Keseru, G. M.; Makara, G. M. Nat. Rev. Drug Disc. 2009, 8, 203.