Discovery of MK-1439, an orally bioavailable non-nucleoside reverse transcriptase inhibitor potent against a wide range of resistant mutant HIV viruses

Article abstract of DOI:10.1016/j.bmcl.2013.12.070

The optimization of a novel series of non-nucleoside reverse transcriptase inhibitors (NNRTI) led to the identification of pyridone 36. In cell cultures, this new NNRTI shows a superior potency profile against a range of wild type and clinically relevant,

Full text of DOI:10.1016/j.bmcl.2013.12.070

Accepted Manuscript
Discovery of MK-1439, an orally bioavailable non-nucleoside reverse tran-
scriptase inhibitor potent against a wide range of resistant mutant HIV viruses
Bernard Côté, Jason D. Burch, Ernest Asante-Appiah, Chris Bayly, Leanne
Bédard, Marc Blouin, Louis-Charles Campeau, Elizabeth Cauchon, Manuel
Chan, Amandine Chefson, Nathalie Coulombe, Wanda Cromlish, Smita
Debnath, Denis Deschenes, Kristina Dupont-Gaudet, Jean-Pierre Falgueyret,
Robert Forget, Sébastien Gagné, Danny Gauvreau, Melina Girardin, Sébastien
Guiral, Eric Langlois, Chun Sing Li, Natalie Nguyen, Rob Papp, Serge
Plamondon, Amélie Roy, Stéphanie Roy, Ria Seliniotakis, Miguel St-Onge,
Stéphane Ouellet, Paul Tawa, Jean-François Truchon, Joe Vacca, Marc Wrona,
Youwei Yan, Yves Ducharme
PII:
S0960-894X(13)01454-6
DOI:
http://dx.doi.org/10.1016/j.bmcl.2013.12.070
BMCL 21178
Reference:
Bioorganic & Medicinal Chemistry Letters
To appear in:
Received Date:
Revised Date:
Accepted Date:
4 November 2013
16 December 2013
17 December 2013
Please cite this article as: Côté, B., Burch, J.D., Asante-Appiah, E., Bayly, C., Bédard, L., Blouin, M., Campeau,
L-C., Cauchon, E., Chan, M., Chefson, A., Coulombe, N., Cromlish, W., Debnath, S., Deschenes, D., Dupont-
Gaudet, K., Falgueyret, J-P., Forget, R., Gagné, S., Gauvreau, D., Girardin, M., Guiral, S., Langlois, E., Li, C.S.,
Nguyen, N., Papp, R., Plamondon, S., Roy, A., Roy, S., Seliniotakis, R., St-Onge, M., Ouellet, S., Tawa, P., Truchon,
J-F., Vacca, J., Wrona, M., Yan, Y., Ducharme, Y., Discovery of MK-1439, an orally bioavailable non-nucleoside
reverse transcriptase inhibitor potent against a wide range of resistant mutant HIV viruses, Bioorganic & Medicinal
Chemistry Letters (2013), doi: http://dx.doi.org/10.1016/j.bmcl.2013.12.070
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Discovery of MK-1439, an orally bioavailable
non-nucleoside reverse transcriptase inhibitor
potent against a wide range of resistant mutant
HIV viruses
Leave this area blank for abstract info.
Bernard Côté∗, Jason D. Burch, Ernest Asante-Appiah, Chris Bayly, Leanne Bédard, Marc Blouin, Louis-Charles Campeau, Elizabeth Cauchon, Manuel
Chan, Amandine Chefson, Nathalie Coulombe, Wanda Cromlish, Smita Debnath, Denis Deschenes, Kristina Dupont-Gaudet, Jean-Pierre Falgueyret,
Robert Forget, Sébastien Gagné, Danny Gauvreau, Melina Girardin, Sébastien Guiral, Eric Langlois, Chun Sing Li, Natalie Nguyen, Rob Papp, Serge
Plamondon, Amélie Roy, Stéphanie Roy, Ria Seliniotakis, Miguel St-Onge, Stéphane Ouellet, Paul Tawa, Jean-François Truchon, Joe Vacca, Marc
Wrona, Youwei Yan and Yves Ducharme

Bioorganic & Medicinal Chemistry Letters
jo u rn al ho me p ag e : w ww .e lse vie r .c om
Discovery of MK-1439, an orally bioavailable non-nucleoside reverse
transcriptase inhibitor potent against a wide range of resistant mutant HIV
viruses
∗
Bernard Côté , Jason D. Burch, Ernest Asante-Appiah, Chris Bayly, Leanne Bédard, Marc Blouin, Louis-
Charles Campeau, Elizabeth Cauchon, Manuel Chan, Amandine Chefson, Nathalie Coulombe, Wanda
Cromlish, Smita Debnath, Denis Deschenes, Kristina Dupont-Gaudet, Jean-Pierre Falgueyret, Robert
Forget, Sébastien Gagné, Danny Gauvreau, Melina Girardin, Sébastien Guiral, Eric Langlois, Chun Sing
Li, Natalie Nguyen, Rob Papp, Serge Plamondon, Amélie Roy, Stéphanie Roy, Ria Seliniotakis, Miguel St-
Onge, Stéphane Ouellet, Paul Tawa, Jean-François Truchon, Joe Vacca, Marc Wrona, Youwei Yana and
Yves Ducharme
Merck Frosst Centre for Therapeutic Research, 16711 Trans Canada Highway, Kirkland, Quebec, Canada H9H 3L1
a Merck Research Laboratories, 770 Sumneytown Pike, PO Box 4, West Point, PA, 19486-0004, United States
ARTICLE INFO
ABSTRACT
Article history:
Received
The optimization of a novel series of non-nucleoside reverse transcriptase inhibitors (NNRTI)
led to the identification of pyridone 36. In cell cultures, this new NNRTI shows a superior
potency profile against a range of wild type and clinically relevant, resistant mutant HIV viruses.
The overall favorable preclinical pharmacokinetic profile of 36 led to the prediction of a once
daily low dose regimen in human. NNRTI 36, now known as MK-1439, is currently in clinical
development for the treatment of HIV infection.
Revised
Accepted
Available online
Keywords:
2009 Elsevier Ltd. All rights reserved.
Non-nucleoside reverse transcriptase
HIV
triazolinone
pyridone
inhibitor
Highly active antiretroviral therapy (HAART) is the standard
of care for the treatment of HIV infection.i Typically, this
protocol recommends the combination of two nucleoside reverse-
transcriptase inhibitors (NRTIs) with either a non-nucleoside
reverse-transcriptase inhibitor (NNRTI), a ritonavir-boosted
protease inhibitor or an integrase inhibitor.ii
viruses bearing mutations K103N and Y181C in patients failing
therapy.viii
NNRTI-based combinations have become first-line therapy
mainly because of their demonstrated efficacies, convenient
dosing regimen and relatively low toxicities.iii These inhibitors
block the polymerase activity of the HIV reverse transcriptase by
binding to an allosteric hydrophobic pocket adjacent to the active
site.iv Efavirenz (1, Fig. 1) is a first generation NNRTI that has
been conveniently co-formulated with NRTIs tenofovir
disoproxil fumarate (TDF) and emtricitabine (FTC) as a once-a-
day fixed-dose combination (Atripla®). Although recommended
for the therapy of treatment-naïve patients, efavirenz suffers from
neurocognitive side effects,v teratogenicityvi and exacerbation of
hyperlipidemia.vii Moreover, the low barrier to genetic resistance
of first generation NNRTIs led to the emergence of resistant
Figure 1. Structures of marketed and lead NNRTIs
———
∗ Corresponding author. Tel.: +1-514-924-1456; e-mail: bernard.cote67@videotron.ca

Second generation NNRTIs etravirine (2) and rilpivirine (3)
efficiently suppress the replication of the K103N resistant
mutants as shown by an improved activity in cell culture assays
(Table 1). Etravirine (200 mg, bid) is approved for use in
treatment-experienced adult patients with multi-drug resistance.ix
With an improved pharmacokinetic profile, the close analog
rilpivirine (25 mg, qd) was recently approved for use in
treatment-naïve patients. Phase III data reveal that at the 96-week
point, a rilpivirine/truvada®x combination was better tolerated
than efavirenz/truvada®.xi However, the virologic failure rate
was twice as high for rilpivirine (14%) than it was for efavirenz
(8%). For patients with viral load greater than 500,000
copies/mL, the response rate is 62% (rilpivirine) versus 81%
(efavirenz). As a result, rilpivirine is not recommended for
treating HIV patients with viral load >500,000 copies/mL. This
difference in treatment durability could be explained by the much
higher ratio of trough concentration over the antiviral activity for
efavirenz versus rilpivirine.
Figure 2. Donor/acceptor hydrogen bonding of the pyrazolopyridine
To validate this strategy, two analogs were synthesized where
the pyridine nitrogen of the pyrazolopyridine was either removed
or shifted by one position (Table 2). The solubility was assessed
by light scattering as a measure of the concentration threshold at
which a DMSO solution of the test compounds precipitate in a
PBS solution. As shown in table 2, both structural modifications
found in pyridone 6 and 7 led to an improved aqueous solubility
(5.2 µM and 12.0 µM respectively) and better oral bioavailability
in rat (30% and 74%). This data set strongly suggested that the
originally observed low solubility and low oral absorption were
not inherent to the pyridone series. We therefore undertook the
synthesis of a library of pyridone analogs to identify a
pyrazolopyridine
replacement
using
the
intermediate
hydroxypyridine 12a (Scheme 1). In parallel with this effort,
SAR at the 4-position of the pyridone was also initiated using
intermediate 12b (Scheme 2).
Pyridone 4 was recently identified as a novel NNRTI with an
improved spectrum of antiviral activity against key mutant strains
(Table 1).xii The related pyridone 5 was also found to have a
similar in vitro profile. However, both analogs suffered from
poor oral bioavailability or high inter-animal exposure
variabilityxiii that limited their development potential. As poor
patient compliance is a key element leading to drug resistance,
optimization of the pharmacokinetic parameters becomes critical
to access a simple dosing regimen that will maximize around-the-
clock viral suppression. In our effort to optimize this new NNRTI
pyridone series, we therefore specifically aimed at developing a
low dose, once daily drug that could be conveniently co-
formulated with other therapeutic agents.
Table 2
Solubility and oral rat bioavailability of substituted pyridone
RTa
IC50 (µM)
WTe
SPREAD 50% NHSb
Solc
Rat PKd
Compd
IC95 (µM)
(µM)
WT
K103N/Y181C
0.069
0.186
F(%)
Clf
18
17
40
5
6
7
0.003
0.001
0.017
0.053
0.029
1.1
5.2
13
30
74
Table 1
Enzyme and Spread-of-virus inhibition of lead NNRTIs
0.006
0.092
12.0
RTa
IC50 (µM)
SPREAD 50% NHSb
IC95 (µM)
a RT: Reverse transcriptase. ECL assay. Values are the geometric mean of
at least two determinations. Assay protocols are detailed in Ref. 14. b IC95 is
defined as the concentration at which the Spread of the virus in inhibited by
>95% in the presence of 50% NHS (normal human serum). Assay protocols
Compound
WTc
WT
K103N
Y181C
0.09
K103N/Y181C
Efavirenz
0.002
0.001
0.001
0.003
0.003
0.039
0.033
0.036
0.008
0.017
1.4
3.2
c
are detailed in Ref.15. Sol: solubility threshold of the DMSO solution in
PBS buffered solution measured by light scattering. d Average of 2 Sprague
Dawley rat dosed at 5 mpk PO (methocel suspension) and 1 mpk IV 60%
PEG200). eWT: Wild type. f Cl: clearance in mL/min/kg.
Etravirine
0.044
0.044
0.012
0.024
0.24
0.59
0.37
0.07
0.07
Rilpivirine
0.12
4
0.02
5
0.06
The synthetic sequence to prepare the hydroxypyridine 12a is
outlined in Scheme 1. Chloropyridine 8 was coupled with 2-
bromo-4-chlorophenol (9) under basic conditions to afford the
biaryl ether 10 in 79% yield. This chloropyridine was then
hydrolyzed to the hydroxypyridine 11 with potassium hydroxide
in 71% yield. Finally, this intermediate was treated with zinc
cyanide in the presence of a catalytic amount of Pd(PPh3)4 to
provide the desired cyano derivative 12a. Scheme 2 describes the
general approach to synthesize the different 4-substituted
pyridones. The synthesis of the common intermediate 12b first
involves the SNAr reaction of commercially available 2-iodo-4-
chlorophenol (14) with the nitropyridine-N-oxide 13 in 80%
yield. The iodophenol was preferred to the previously used
bromo analog in order to avoid the formation of a regioisomeric
mixture during the cyanation reaction. Sequential treatment of the
nitropyridine-N-oxide 15 with acetylbromide in acetic acid
followed by the reaction of the crude material with phosphorus
tribromide in chloroform provided the dibromopyridine 16 in
87% overall yield. Hydrolysis of the bromopyridine with
potassium hydroxide (72% yield) followed by the quantitative
cyanation of the iodoaryl moiety gave the 4-bromo-2-
hydroxypirydine 12b. This key intermediate was then
fonctionnalized by taking advantage of the selective reactivity of
the bromide. The final assemblage was completed by alkylating
the hydroxypyridines 12b-f as describe before (see ref. 12) with
a RT: Reverse transcriptase. ECL assay. Values are the geometric mean of
at least two determinations. Assay protocols are detailed in Ref. xiv. b IC95 is
defined as the concentration at which the Spread of the virus is inhibited by
>95% in the presence of 50% NHS (normal human serum). Assay protocols
are detailed in Ref. xv. c WT: Wild type.
One of the striking elements that initially oriented our efforts
to improve the oral bioavailability of the pyridone series was the
poor aqueous solubilityxvi of 5 (0.2 ng/mL in water). This low
solubility, as well as the high crystallinity of 5 (m.p. = 299oC),
could be rationalized by the analysis of the solid-state x-ray
structure of a close analog sharing the pyrazolopyridine moiety
found in 5 (Fig. 2). We hypothesized that disruption of the strong
donor/acceptor hydrogen bond motif of the pyrazolopyridine
would weaken the crystal lattice and enhance the solubility.

the protected 3-bromomethyl pyrazolopyridine followed by TFA-
mediated hydrolysis of the tert-butyl carboxylate.
Scheme 1. Reagents and conditions: (a) K2CO3, NMP, 120oC; (b) KOH, tert-BuOH, 75oC; (c) Zn(CN)2, Pd(PPh3)4, DMF, 100oC.
Scheme 2. Reagents and conditions: (a) K2CO3, DMF, 55oC; (b) AcBr, AcOH, 80oC; (c) PBr3, CHCl3, 60oC; (d) KOH, tert-BuOH;
(c) Zn(CN)2, Pd(PPh3)4, DMF, 100oC; (f) K2CO3, bromide, DMF, 55oC, then TFA.
rats. With the fluorinated analog 26, we were able to extend the
rat half-life to 4 hours with an oral bioavailability of 65% but
unfortunately, a significant potency shift was observed in the
cellular assay in the presence of 50% NHS (IC95 = 76 nM).
The biological activity and the rat pharmacokinetic properties
of pyrazolopyridines 17-21 were evaluated (Table 3). In general,
most of the functional groups were very well tolerated with low
nanomolar enzyme inhibition activity. In the Spread assay,
bromo derivative 17 was identified as the most potent analog
ever prepared in the pyridone series with an IC95 = 0.004 µM
against the wild type virus and an IC95 = 0.021 µM against the
double mutant K103N/Y181C. In cell culture, the antiviral
potency of all these new analogs is superior to the benchmark
NNRTIs efavirenz and rilpivirine. The key differentiation factor
amongst them is their in vivo ADME properties. The CF3-
substituted pyridone 5 presents a substantially longer elimination
half-life (t1/2 = 7 h) in rats compared to its close analogs. Further
studies in dogs (data not shown) corroborated this
pharmacokinetic trend and the strong electron withdrawing CF3
group was therefore considered as optimal.
Table 3
Biological activity and rat half-life of 4-substituted pyridones.
RTa
IC50 (µM)
WTc
Spread 50% NHSb
Rat t1/2
(h)d
Compd
X
IC95 (µM)
WT
K103N/Y181C
4
Cl
CF3
0.003
0.003
0.002
0.007
0.005
0.009
0.007
0.008
0.017
0.004
0.012
0.014
0.015
0.012
0.069
0.069
0.021
0.096
0.044
0.033
0.11
2.2
7.0
1.7
0.8
1.3
1.5
1.5
5
The next series of pyridone analogs were synthesized by the
alkylation of intermediate 12a with different heterocycle
derivatives (Table 4). Using standard reaction conditions (K2CO3,
DMF) a 48-membered library was rapidly built. The specific aim
of this exercise was to identify compounds that would retain the
antiviral activity of 5, and would present increased aqueous
solubility and ultimately improved systemic exposure following
oral administration in pre-clinical species. Inhibitors 22 to 25 are
pyrazolopyridine derivatives that were substituted to increase the
polarity of the compounds (22 and 23) or to reduce the basicity of
the pyridine nitrogen (24 and 25). All four analogs were found to
be potent, but suffered from poor rat pharmacokinetics.xvii We
have previously shown in table 2 that the potent regioisomeric
pyrazolopyridine 7 is well absorbed but eliminated too rapidly in
17
18
19
20
21
Br
CH3
CF2CH3
SCH3
c-Pr
a RT: Reverse transcriptase. ECL assay. Values are the geometric mean of
at least two determinations. Assay protocols are detailed in Ref. 14. b IC95 is
defined as the concentration at which the Spread of the virus in inhibited by
>95% in the presence of 50% NHS (normal human serum). Assay protocols
are detailed in Ref.15. c WT: Wild type. d Average of 2 Sprague Dawley rats
dosed at 1 mpk IV (60% PEG200).
Greater structural diversity was explored with the following
heterocycles. Despite their good intrinsic potency against the
enzyme, the large lipophilic quinoline 27 and benzoisoxazole 28

a
RT: Reverse transcriptase. ECL assay. Values are the geometric mean of at
showed largely shifted potencies in the Spread assay. The
incorporation of small heterocyclic rings to produce inhibitors
such as 4-methylthiazole 29, generally resulted in significantly
increased aqueous solubility. While this finding was true for most
small rings, the nature of the heterocycle and its substitution
pattern had a tremendous impact on the antiviral potency. While
substitution with a methyl group at the 4-position seems to assure
enzyme activity in the thiazole series (29 and 31 vs 30), this
observation did not translate well for the pyrazole 32 (IC50 = 140
b
least two determinations. Assay protocols are detailed in Ref. 14. IC95 is
defined as the concentration at which the Spread of the virus in inhibited by
>95% in the presence of 50% NHS (normal human serum). Assay protocols
are detailed in Ref. 15. c Sol: solubility threshold of the DMSO solution in
PBS buffered solution measured by light scattering.
In addition to the 4-methyl substitution of the triazolinone,
one of the key structural features contributing to the good
antiviral potency of inhibitor 36xviii is the presence of the N-NH
motif that was also present in the pyrazolopyridine series. In an
analogous biaryl ether series, Sweeney et al. have described a
series of heterocycles sharing this structural feature.xix Based on
crystal structure analysis with HIV-RT, they highlighted the role
of the N-NH acceptor-donor motif that engages a pair of
hydrogen-bonds with the K103 backbone of the RT enzyme. This
type of interaction was also observed in the binding of pyridone
36 with HIV-RT in the structural elucidation of a co-crystal by
X-ray, as shown in Figure 3.
nM), the imidazole 33 (IC50 = 300 nM) and the triazole 34 (IC50
=
43 nM). In the triazolinone series though, methylation at the 4-
position as described in Scheme 3, was found to be beneficial
with a 5-fold increase in enzyme potency (35 vs 36).
Conversely, the slight increase in steric hindrance of the 4-ethyl
substituted triazolone 37 negatively impacted the cell culture
activity (IC95 > 125 nM).
Table 4.
Potency and solubility of alkylated pyridones
Y
Figure 3. X-ray crystal structure of compound 36 bound to HIV-RT. The
wild-type RT complex structure has been deposited in the Protein Data Bank
under accession code 4NCG.
As seen in Table 5, inhibitor 36 presents an exceptional in
vitro profile against clinically relevant resistant viruses.
Compared to efavirenz, pyridone 36 is 33-fold more active
against K103N and 59-fold more potent against the double
mutant K103N/Y181C. Compared to rilpivirine, inhibitor 36 is
respectively 5 and 7-fold more potent against the mutant viruses
Y181C and K103N/Y181C respectively.
Table 5
Antiviral activity of pyridone 36 in cell culture
SPREAD IC95 (µM) with 50% NHSa
Compound
WT
K103N
0.042
1.4
Y181C
0.025
0.089
0.120
K103N/Y181C
36
0.019
0.039
0.036
0.054
3.2
Efavirenz
Rilpivirine
0.044
0.37
a IC95 is defined as the concentration at which the Spread of the virus in
inhibited by >95% in the presence of 50% NHS (normal human serum).
Assay protocols are detailed in Ref. 15.
In addition to the above mutant substituted viruses, pyridone
36 was tested against a panel of 15 mutant viruses (Monogram
Biosciences) and compared to efavirenz, rilpivirine and lead
inhibitor 5.

bioavailability of our new NNRTI confers a 16-fold increase in
systemic exposure (AUCN = 3.9 µM*h). In dog, the same net
result is also observed with a 26-fold improvement in exposure.
In this case, a combination of low clearance (Cl = 0.36
mL/min/kg) and better oral absorption (F = 52%) is responsible
for the high observed AUCN of 44 µM*h. The overall favorable
pharmacokinetic profile of 36 in preclinical species, combined to
a low metabolic turnover (<10%) in human liver microsomes and
hepatocytesxx lead to the prediction of a once daily low dose
regimen in human.
700
600
500
400
300
200
100
0
With a broad spectrum of antiviral activity against clinically
relevant mutant viruses, analogs from the new pyridone series
clearly meet a mandatory criterion for next generation NNRTIs.
Unfortunately, poor oral bioavailability in preclinical species was
a key liability originally associated with this series. Using a
simple synthetic approach, we rapidly built a library of inhibitors
that led to the identification of pyridone 36. In cell culture, this
new inhibitor has a superior profile against the wild type and
K103N/Y181C viruses compared with benchmark compounds
efavirenz, etravirine and rilpivirine. The increased aqueous
Efavirenz
Rilpivirine
Compd 5
Compd 36
Mutant viruses
Figure 4. Fold change in activity (IC50 versus the control CNDO virus) of
NNRTIs in a panel of 15 mutant viruses (Monogram Biosciences).
A
maximum cut-off of 625-fold is shown. The data for the inhibitors are
presented as follows: efavirenz (purple), rilpivirine (green), compound 5
(red), compound 36 (blue).
solubility of pyridone 36 translated into
a significant
improvement of pharmacokinetic parameters in preclinical
species. NNRTI 36, now known as MK-1439, is currently in
clinical development for the treatment of HIV infection.
As indicated in Figure 4, efavirenz was less active against a
number of the mutant viruses in contrast to the second-generation
inhibitor, rilpivirine. Pyridone 36 maintained the potent antiviral
activity of compound 5 and demonstrated a robust activity
against the mutant viruses. It was less active against the rare
mutants harboring the Y188L and V106A/G109A/F227L amino
acid changes for which two or more nucleotide changes are
required. Additional profiling of the antiviral activity of
compound 36 on a panel of 96 mutant viruses shows a similar
robust activity (to be reported in a future publication).
Table 6
Comparative pharmacokinetic parameters of pyridones 5 and 36 in rat and
dog
Species
Rata
Parameters
Vd (L/kg)
5
8.8
15
7
36
2.3
5.4
4.4
57
Cl (mL/min/kg)
t1/2 (hr)
F (%)
AUCN (µM*h)c
15
0.25
1.5
1.8
10
9
As shown before, the solubility threshold of compound 36 (45
µM) is significantly increased compared to the original lead
pyridone 5 (1.0 µM) in water. At both pH 4 and 8, the
equilibrium solubility of 36 is 6 µg/mL in comparison to <0.1
µg/mL for 5. Solubility in fasted simulated intestinal fluid
(FaSSIF) went up from 1.3 µg/mL for pyrazolopyridine 5 to 130
µg/mL for the crystalline triazolinone 36. These improved
3.9
1.2
0.36
37
Vd (L/kg)
Cl (mL/min/kg)
t1/2 (hr)
Dogb
F (%)
52
AUCN (µM*h)
1.7
44
physicochemical properties correlate with
pharmacokinetic profile for 36 in rats and dogs as presented in
a
superior
a
Average of 2 Sprague Dawley rats for each doses. 5 was dosed IV at 1
mpk (80%PEG200) and PO at 5 mpk (Ball-milled, 0.5% methocel). 36 was
dosed IV at 1 mpk (60%PEG200) and PO at 5 mpk (Ball-milled, 0.5%
methocel). b Average of 2 Beagle dogs for each doses. 5 was dosed IV at 0.5
mpk (80%PEG200) and PO at 1 mpk (Ball-milled, 0.5% methocel). 36 was
dosed IV at 0.5 mpk (60%PEG200) and PO at 1 mpk (Ball-milled, 10%
Tween). c Normalized for 1 mpk from 0-24h.
table 6.
Scheme 3. Reagents and conditions: (a) K2CO3, DMF, -10oC; (b) MeI or EtI,
K2CO3, DMF.
Acknowledgements
The authors wish to thank Neville Anthony, Christopher
Burgey and Ming-Tain Lai for reviewing the manuscript.
Although the clearance of 36 (Cl = 5.4 mL/min/kg) is lower
compared to 5 (15 mL/min/kg) in rats, the half-life of 36 is
slightly shorter due to its smaller volume of distribution (Vd).
Nevertheless, this lower Vd combined with the good rat
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Lecocq, P.; Kraus, G.; Picchio, G.; de Bethune, M.-P. Antiviral Ther. 2009,
14(1), 103.
ix. Schiller, D. S.; Youssef-Bessler, M. Clin. Res. 2009, 31(4), 692.
x. Truvada® is a fixed dose combination of 300 mg of tenofovir disoproxil
fumarate and 200 mg of emtricitabine.
xi. Sanford, M. Drugs 2012, 72(4), 525.
xii. Gomez, R.; Jolly, S.; Williams, T.; Tucker, T.; Tynebor, R.; Vacca, J.;
McGaughey, G.; Lai, M.T.; Felock, P.; Munshi, V.; DeStefano, D.; Touch, S.;
Miller, M.; Yan, Y.; Sanchez, R.; Liang, Y.; Paton, B.; Wan, B.L.; Anthony,
N. Bioorg. Med. Chem. Lett. 2011, 21, 7344.
xiii. For analog 4, F = 57% in rat at 10 mpk as a methocel suspension but the
exposure varied from 1.5 µM*h up to 38 µM*h. For analog 5, F = 15% in rat
at 5 mpk as a methocel suspension. In dog F = 9% at 1 mpk as a methocel
suspension.
xiv. Saggar, S. A.; Sisko, J. T.; Tucker, T. J.; Tynebor, R. M.; Su, D.-S.;
Anthony, N. J. U.S. Patent Appl. US 2007/021442 A1, 2007.
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Roth, E.; Sardana, V. V.; Schlabac, A. J.; Graham, P. I.; Condra, J. H.;
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1994, 91, 4096.
xvi. Aqueous equilibrium solubility was evaluated by stirring excess solid in
water at room temperature for 24h in the absence of light. The solubility was
measured by HPLC.
xvii. For analog 24, F = 0% in rat. For analog 25, F = 15% in rat.
xviii. 36: m.p. 280 oC. 1H NMR (500 MHz): δ 3.11 (s, 3H), 5.16 (s, 2H), 6.67
(d, 1H), 7.53 (s, 1H), 7.61 (s, 1H), 7.75 (s, 1H), 7.88 (d, 1H), 11.68 (s, 1H).
xix. Sweeney, Z. K.; Acharya, S.; Briggs, A.; Dunn, J. P.; Elworthy, T. R.;
Fretland, J.; Giannetti, A. M. Bioorg. Med. Chem. Lett. 2008, 18, 4348.
xx. Microsomes: 0.5 mg/mL protein with 1 µM cpd + 1 mM NADPH,
incubated for 30 min at 37 oC; hepatocytes: 106 cells + 1 µM cpd, incubated
for 60 min at 37 oC.

*Graphical Abstract (for review)
Cl
CN
O
CH3
N
O
O
N
N
NH
F3C
(MK-1439)