2- and 3-Fluoro-3-deazaneplanocins, 2-fluoro-3-deazaaristeromycins, and 3-methyl-3-deazaneplanocin: Synthesis and antiviral properties

Article abstract of DOI:10.1016/j.bmc.2015.07.039

The 3-deaza analogs of the naturally occurring adenine-based carbocyclic nucleosides aristeromycin and neplanocin possess biological properties that have not been optimized. In that direction, this paper reports the strategic placement of a fluorine atom

Full text of DOI:10.1016/j.bmc.2015.07.039

Bioorganic & Medicinal Chemistry xxx (2015) xxx–xxx
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
2- and 3-Fluoro-3-deazaneplanocins, 2-fluoro-3-
deazaaristeromycins, and 3-methyl-3-deazaneplanocin: Synthesis
and antiviral properties
⇑
Chong Liu, Qi Chen, John D. Gorden, Stewart W. Schneller
Molette Laboratory for Drug Discovery, Department of Chemistry and Biochemistry, Auburn University, Auburn, AL 36849-5312, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
The 3-deaza analogs of the naturally occurring adenine-based carbocyclic nucleosides aristeromycin and
neplanocin possess biological properties that have not been optimized. In that direction, this paper
reports the strategic placement of a fluorine atom at the C-2 and C-3 positions and a methyl at the C-3
site of the 3-deazaadenine ring of the aforementioned compounds. The synthesis and S-adenosylhomo-
cysteine hydrolase inhibitory and antiviral properties of these targets are described. Some, but not all,
compounds in this series showed significant activity toward herpes, arena, bunya, flavi, and
orthomyxoviruses.
Received 24 May 2015
Revised 11 July 2015
Accepted 19 July 2015
Available online xxxx
Keywords:
Carbocyclic nucleosides
Fluoro 3-deazaadenine nucleosides
Antiviral activity
Ó 2015 Elsevier Ltd. All rights reserved.
1
. Introduction
The clinical success of entecavir (1)1 and abacavir (2)2 (Fig. 1)
Continuing our interest in the 3-deaza category,12 we recently
reported that 3-halo-3-deazaadenine carbocyclic nucleosides dis-
5d,e
played promising activity
that prompted us to further explore
have given carbocyclic nucleosides a prominent place among
antiviral drug therapeutics and, as a consequence, serve to invigo-
rate the search for other carbocyclic antiviral leads.1 While com-
pounds 1 and 2 are guanine and diaminopurine based agents (as
prodrugs of the active triphosphates),4 finding carbocyclic nucle-
this structural characteristic with the synthesis and antiviral
status of 2- and 3-fluoro-3-deazaneplanocins (7 and 8), 2-fluoro-
3-deazaaristeromycins (9), and 3-methyl-3-deazaneplanocin (10)
(Fig. 1).
,3
Target 7a was selected as the 3-deaza congener of the antiviral
5
13
oside antivirals based on the adenine ring continues in our and
candidate 2-fluoroneplanocin while 8a offers the 3-fluorolog of
6
5e
other laboratories as a result of their inhibition of S-adenosylho-
the broad spectrum agent 3-bromo-3-deazaneplanocin.
mocysteine hydrolase.7 Aristeromycin (3) and neplanocin A (4
herein referred to as neplanocin) represent the parent structures
in those studies.
Compound 9a places it (i) along side of 3-fluoro-3-
14
deazaaristeromycin, which has favorable antiviral promise, and
(ii) as the 3-deaza analog of the anti-malarial prospect 2-fluo-
1
5
Because of their structural similarity to adenosine, the naturally
occurring 3 and 4 have been shown to possess biological character-
istics,8 including inhibition of S-adenosylhomocysteine hydrolase
roaristeromycin. The compound represented by 10 became part
of this study to ascertain whether 3-alkyl-3-deazaneplanocins
offer antiviral potential and to provide access to functionalized
carbon units at the 3-deaza site for further agent discovery. The
7
0
9
(
SAHase) and 5 -nucleotide formation that have been designated
0
as loci for their antiviral properties. The synthetic 3-deaza analogs
of 3 and 4 (i.e., 5 and 6) arose to expand on the structural features
of 3 and 4 and have been found to possess similar antiviral profiles
most often associated with their potent inhibition of SAHase
5 -homo targets (7b, 8b, and 9b) have also been included as a con-
0
16a
sequence of the antiviral properties of 5 -homoneplanocin
5 -homoaristeromycin.
and
0
16b
0
The 5 -nor derivative of 9a (i.e., 9c)
0
follows from the significant antiviral properties of 5 -nor
1
0
5d
(
6 > 5), which, in turn, affects AdoMet-dependent methylation
aristeromycin.
reactions, including those of viral origin.6 Also, the class of
6
3
-deazaadenine nucleosides has drawn attention since they are
2
2
. Results and discussion
less susceptible to adenosine deaminase and adenosine kinase
and, consequently, less toxic than their aza parents.11
.1. Synthesis
⇑
Corresponding author. Tel.: +1 334 844 6947; fax: +1 334 844 0239.
E-mail address: schnest@auburn.edu (S.W. Schneller).
The plan to the target compounds was designed to subject read-
5
e
16a
ily accessible cyclopentenols 11 or 12
(shown in Scheme 2)
http://dx.doi.org/10.1016/j.bmc.2015.07.039
968-0896/Ó 2015 Elsevier Ltd. All rights reserved.
0
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C. Liu et al. / Bioorg. Med. Chem. xxx (2015) xxx–xxx
Figure 1. Relevant purine carbocyclic nucleosides.
and cyclopentanols 25, 26,14 and 2714 (shown in Scheme 3) to a
5
e
conditions gave targets 7a, 7b, 8a, and 8b. A palladium catalyzed
cross-coupling reaction with trimethylaluminum converted 23
into 24, which was followed by the same silyl deprotection as
used previously to afford 10.
1
2a
Mitsunobu procedure
(
with requisite 3-deazaadenines 13
1
4
5e
Scheme 1), 17 and 18 (shown in Scheme 2). The preparation
of 13 began with 4,6-difluoroimidazo[4,5-c]pridine (2,6-difluoro-
3
-deazaadenine, 14)1 with the awareness that the 6-fluoro (pur-
7
In a similar approach, the three aristeromycin targets 9a–c were
synthesized according to Scheme 3. Subjecting 13 to Mitsunobu
ine numbering) would be more susceptible to displacement by
ammonia than a chloro at that position, which would require
hydrazine and Raney nickel conditions as is common for 3-deaza-
5
e
14
14
coupling conditions with 25, 26, and 27 smoothly gave prod-
ucts 28–30. Target compounds 9a–c were subsequently obtained
after acidic removal of the silyl protecting groups.
1
2a
adenine nucleosides.
This conclusion was validated with the
facile conversion of 14–15. Realizing that the free amino on 15
would compete with the Mitsunobu coupling, it was transformed
into the tri-Boc derivative 16 that was, in turn, converted to 13
with tetrabutylammonium fluoride.5e Besides NMR data, the
structure of 13 was further confirmed by X-ray crystallography.
The five neplanocin analog targets (7a/7b, 8a/8b, and 10) were
2.2. Antiviral and enzyme assay results
Tables 1 and 2 summarizes the viruses toward which the com-
1
4,18
pounds synthesized showed activity.
The 3-deaza-3-fluorone-
planocin series (8a, 8b) (Table 1) exhibit broad antiviral activities
against herpes (dsDNA), arena ((ꢀ)ssRNA), bunya ((ꢀ)ssRNA), flavi
((+)ssRNA), and orthomyxoviruses ((ꢀ)ssRNA). Target 8a showed
potent activities against tacaribe virus, human cytomegalovirus
(HCMV), influenza A (H5N1), influenza B and moderate activity
1
4
synthesized according to Scheme 2 employing 11, 12 and 13, 17
and 18,5e under Mitsunobu conditions12a to yield the coupling
products 19–23. That the coupling occurred on the purine N-9
position was confirmed by the X-ray crystal structures of 8a and
0
8
b. Removal of the silyl protecting groups of 19–22 under acidic
against Rift Valley fever and dengue virus. The 5 homo analog
3 2
Scheme 1. Synthesis of 13. Reagents and conditions: (a) NH /MeOH, 93%; (b) (Boc) O, DMAP, THF; (c) TBAF, THF, 53% from 15.
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C. Liu et al. / Bioorg. Med. Chem. xxx (2015) xxx–xxx
3
3 3
Scheme 2. Synthesis of 2-fluoro-(7a, 7b), 3-fluoro-(8a, 8b), and 3-methy-(10) 3-deazaneplanocins. Reagents and conditions: (a) DIAD, PPh , THF; (b) HCl/MeOH; (c) AlMe ,
Pd(PPh ) , THF, yields in Section 3.
3 4
0
Scheme 3. Synthesis of 2-fluoro-3-deazaaristeromycin and its 5 -modified analogs (9a–c). Reagents and conditions: (a) DIAD, PPh
3
, THF; (b) HCl/MeOH yields in Section 3.
Table 1
Antiviral data for the active compounds
Cell-line
8a
8b
10
IC50
(
lM)
CC50
(l
M)
SI
IC50
(l
M)
CC50
(lM)
SI
IC50
(lM)
CC50
(
lM)
SI
Yellow fever
Rift Valley fever
Tacaribe
Dengue
HCMV
Vero
>224
6.4
<0.36
7.1
0.3
1.0
224.0
36.0
114.2
35.7
>300
32.5
>357
–
5.6
1.5
1.3
<0.34
15.0
5.1
>340
3.4
>240
2.6
>560
7.3
759.0
>2.4
>340
3.6
>36
1.2
>228
6.4
>362
36.0
83.3
228.0
247.0
250.0
>362
>100
–
72.0
–
38.6
3.3
>320
Vero 76
Vero 76
Vero
HFF
MDCK
MDCK
>317
5.0
>1035
34.0
>1000
190.4
108.8
>300
>340
>340
Influenza A (H5N1)
Influenza B
139.0
1.0
76.0
1.1
<0.36
Control drugs: Yellow fever, infergen IC50 = 0.00001
l
g/mL, CC50 > 0.01; Rift Valley fever, ribavirin, IC50 = 37.3
l
M, CC50 > 1000
l
M; Tacaribe, ribavirin, IC50 = 26.7
l
l
M,
M.
CC50 > 1000
lM; Dengue, infergen IC50 = 0.0002
lg/mL, CC50 > 0.1 g/mL; HCMV, ganciclovir, IC50 = 3.6 M, CC50 > 100
l
l
l
M; Infuenza B, ribavirin IC50 = 9.0
l
M, CC50 > 100
Table 2
Antiviral data for additional active compounds
Cell-Line
7a
7b
9a
9b
9c
IC50
M)
CC50
SI
IC50
M)
CC50
SI
IC50
M)
CC50
SI
IC50
CC50
SI
–
IC50
M)
CC50
M)
SI
(
l
(
lM)
(
l
(l
M)
(
l
(lM)
(
lM)
(lM)
(
l
(
l
Yellow
fever
Vero
6.8
>100
>50 29
>100
>3.4
2.1
>355
>170
–
–
15
>100
>6.7
HCMV
HBV
HFF
HepG
8.7
0.67
217.5
11
25
17
<0.1
0.99
>300
7.5
>300
8
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
22.2.15
Measles
CV-1
8.5
>100
>12 89.8
M, CC50 = 2176
>100
>1
9.6
>355
>37
162
>338
>2.1 30.2
>100
>3
Control drugs: HBV, lamivudine, IC50 = 0.039
l
l
M; measles, 3-deazaguanine, IC50 = 4.1
l
M, CC50 = 250
l
M. For yellow fever and HCMV, see Table 1.
8
b maintained the potent activity against tacaribe virus and
yellow fever virus and moderate activity against measles virus.
The two C-5 -side chain modified analogs (9b, 9c) lost both antivi-
ral activities (Table 2).
0
improved (relative to 8a) activity against yellow fever and Rift
Valley fever while displaying, in varying degrees, reduced activity
toward dengue, HCMV, influenza A (H5N1) and influenza B. The
Because of the potent inhibitory properties of 3-deazane-
planocin and 3-deazaaristeromycin toward S-adenosylhomocys-
3
-methyl analog 10 has similar antiviral trend as 8b except for
the loss of activity against Rift Valley fever virus and dengue virus.
-Deaza-2-fluoroneplanocin 7a produced broad-spectrum
1
4
teine (AdoHcy) hydrolase, and as their generally accepted mode
of antiviral properties, the target compounds in this study were
evaluated against this enzyme (Table 3). Of the compound collec-
tion, 8a is the most potent AdoHcy hydrolase inhibitor and showed
the best antiviral profile. This suggests inhibition of AdoHcy hydro-
lase activity could serve, in the future, as an indicator of possible
antiviral activity for 8a analogs. On the other hand, 7a and 7b
3
antiviral activities against yellow fever, HCMV, HBV (particularly
noteworthy) and measles viruses (Table 2). With a C-5 modified
side chain, compound 7b gave potent results toward HCMV and
maintained the activity (relative to 7a) against HBV. 3-Deaza-2-flu-
oroaristeromycin 9a (Table 2) produced high activity against
0
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C. Liu et al. / Bioorg. Med. Chem. xxx (2015) xxx–xxx
Table 3
evaporation under reduced pressure to give an oil residue (16,
AdoHcy hydrolase inhibition activities (nM)
2
.4 g), which was used directly for the next step.
7a
7b
8a
8b
9a
9b
9c
10
Tetrabutylammonium fluoride (11 mL, 1M in THF, 11 mmol)
was added to a solution of 16 in THF (40 mL). This reaction mixture
was stirred at room temperature for 6 h. The solvent was removed
by evaporation under reduced pressure and the residue purified by
IC50
1400
>10,000
6.8
145
3320
3750
1000
41
Control inhibitor: 3-deazaneplanocin (6) IC50 = 9.3.14
column chromatography (EtOAc/MeOH, 10:1) to afford 13 (1.1 g,
1
5
(
3% from 15) as a white solid. H NMR (250 MHz, CDCl
3
) d 11.66
C NMR
lacked hydrolase inhibition, but displayed some high antiviral
activities. This may indicate that they are acting by a mechanism
not exclusively involving the hydrolase.
1
3
br, 1H), 8.16 (s, 1H), 7.06 (s, 1H), 1.40 (s, 18H);
(
5
3
62.9 MHz, CDCl ) d 180.6, 159.4, 155.8, 151.1, 144.6, 84.0, 77.2,
3
+
3.6, 27.8; HRMS calcd for C16
53.1639.
22 4 4
H N O F [M+H] 353.1625, Found
2
.3. Conclusion
3
.1.2. General procedure for the Mitsunobu reaction of 3-
Placement of a fluorine atom on biological molecules has
opened new leads for drug discovery.19 Similar consequences have
deazaadenines with cyclopentanols and cyclopentenols and the
hydrolysis of coupling products
To a solution of cyclopentanols 11, 12, 25–27 (1 mmol) and
triphenylphosphine (1.5 mmol) in THF (10 mL) was added
arisen herein with 3-deazaneplanocin and 3-deazaaristeromycin
from the newly synthesized 2-fluoro- (7) and 3-fluoro-3-deazane-
planocins (8) and, to a less extent, 2-fluoro-3-dezaaristeromycins
3
-deazaadenines 13, 17, or 18 (1 mmol). This suspension was
(
9). Antiviral activity has been found for DNA viruses (HCMV, her-
cooled to 0 °C and DIAD (1.5 mmol) added dropwise. After comple-
tion of the addition, the reaction mixture was warmed to room
temperature and stirred at this temperature for 12 h. The solvent
was removed under reduced pressure and the residue purified by
column chromatography (hexanes/EtOAc, 3:1) to afford 19–23
and 28–30, which are contaminated with DIAD byproducts.
Products 19–22 and 28–30, were dissolved in a mixture of
MeOH (5 mL) and 2 N HCl (4 mL) and the resulting solution was
brought to reflux for 2 h and then cooled to room temperature.
After addition of basic resin (Amberlite IR67) for neutralization of
the solution and filtration, the solvent was removed under vacuum
and the residue purified by column chromatography
pes; HBV, hepadna) and for RNA viruses (yellow fever and dengue,
flavi; Rift Valley fever, bunya; Tacaribe, arena; influenza A and B,
orthomyxo; and measles, paramyxo). Antiviral results for 8a corre-
lates with its inhibition of AdoHcy hydrolase while this correlation
was not found for 7a and, certainly, 7b. The 9 series was both poor
AdoHcy hydrolase inhibitors and antiviral candidates and, with the
comparatively moderate hydrolase activity and their small range of
antiviral effects, 8b and 10 appear act by more than hydrolase inhi-
bition. It should be noted that the 3-fluoro-3-deazaneplanocin (8a)
reported here offers greater activity diversity than the correspond-
ing 3-fluoro-3-deazaaristeromycin congener.14
(
EtOAc/MeOH, 10:1) to give 7a, 7b, 8a, 8b and 9a–c.
3
3
. Experimental section
3
.1.3. (1R,4R,5S)-3-(Hydroxymethyl)-4,5-dihydroxy-2-
.1. Chemistry
cyclopenten-l-yl]-4-amino-6-fluoroimidazo[4,5-c]pyridine (7a)
1
Yield: 62% (for two steps), white solid. H NMR (400 MHz,
The combustion analyses were performed at Atlantic Microlab,
DMSO-d
.78 (m, 1H), 5.25 (d, J = 7.6 Hz, 1H), 5.20 (m, 1H), 5.09 (d,
J = 5.6 Hz, 1H), 5.04 (t, J = 5.6 Hz, 1H), 4.37, (t, J = 5.2 Hz, 1H), 4.13
6
) d 7.94 (s, 1H), 6.60 (br, 2H), 6.28 (d, J = 1.6 Hz, 1H),
1
13
Norcross, GA. H and C NMR spectra were recorded on either a
Bruker AV 600 spectrometer (600 MHz for proton and 150 MHz
for carbon) or a Bruker AV 400 spectrometer (400 MHz for proton
and 100 MHz for carbon), referenced to internal tetramethylsilane
5
13
(
m, 2H), 4.01 (dd, J = 13.2, 6.0 Hz, 1H).
DMSO-d ) d 150.4 (d, J = 157 Hz), 142.1, 141.5, 140.5, 129.4,
27.3 (d, J = 11 Hz), 125.8 (d, J = 21 Hz), 123.8, 78.4, 72.6, 67.2,
9.0. Anal. Calcd for C12 : C, 51.43; H, 4.68; N, 19.99.
C NMR (150 MHz,
6
(
TMS) at 0.0 ppm. The mass spectral data was determined using a
1
5
Waters Micromass Q-TOF Premier Mass Spectrometer. The reac-
tions were monitored by thin-layer chromatography (TLC) using
4 3
H13FN O
Found: C, 51.16; H, 4.60; N, 19.76.
0
.25 mm Whatman Diamond silica gel 60-F254 precoated plates
with visualization by irradiation with a Mineralight UVGL-25 lamp.
Column chromatography was performed on Whatman silica,
3
.1.4. (1R,4R,5S)-3-(2-Hydroxyethyl)-4,5-dihydroxy-2-
cyclopenten-l-yl]-4-amino-6-fluoroimidazo[4,5-c]pyridine (7b)
2
30–400 mesh, and 60 Å using elution with the indicated solvent
1
Yield: 65% (for two steps), white solid. H NMR (600 MHz,
system.
CD
3
OD) d 8.05 (s, 1H), 6.24 (s, 1H), 6.05 (d, J = 1.8 Hz, 1H), 5.30
(
d, J = 5.4 Hz, 1H), 4.59 (m, 1H), 4.35 (t, J = 5.4 Hz, 1H), 3.61 (t,
3
.1.1. 4-(N,N-Di-tert-butyloxycarbonylamino)-6-fluoroimidazo
1
3
J = 6.6 Hz, 2H), 2.19 (m, 1H), 1.97 (m, 1H). C NMR (100 MHz,
DMSO-d ) d 148.9 (d, J = 185 Hz), 148.8, 141.5, 140.2, 129.5,
1
5
1
[
4,5-c]pyridine (13)
1
7
6
A solution of 14 (1.1 g, 7.1 mmol) in MeOH (30 mL) was satu-
rated with NH at 0 °C and then heated at 90 °C for 24 h in a Parr
stainless steel, sealed reaction vessel. The solvent was removed
27.2 (d, J = 12 Hz), 125.8 (d, J = 21 Hz), 125.5, 79.0, 78.0, 74.8,
9.4, 33.0. Anal. Calcd for C13 : C, 53.06; H, 5.14; N,
9.04. Found: C, 53.40; H, 5.21; N, 18.75.
3
4 3
H15FN O
under reduced pressure, and the residue purified by column chro-
matography (EtOAc/MeOH, 7:1) to afford 15 as a white solid (1.0 g,
1
9
6
1
3%). H NMR (400 MHz, DMSO-d
6
) d 12.51 (br, 1H), 8.02 (s, 1H),
3.1.5. (1R,4R,5S)-3-(Hydroxymethyl)-4,5-dihydroxy-2-
+
.50 (br, 2H), 6.20 (s, 1H) HRMS Calcd for C
53.0576 Found 153.0591.
H FN
6 5 4
[M+H] :
cyclopenten-l-yl]-4-amino-7-fluoroimidazo[4,5-c]pyridine (8a)
1
Yield: 55% (for two steps), white solid. H NMR (400 MHz,
To a suspension of 15 (0.95 g, 6.25 mmol) and 4-(dimethy-
lamino)pyridine (DMAP, 77 mg, 0.63 mmol) in dry THF (50 mL)
was added 5.5 g (25 mmol) of (Boc) O. After stirring for 24 h at
room temperature, the reaction mixture was quenched by adding
O (50 mL) followed by extraction with EtOAc and the extracts
dried (anhydrous Na SO ). The solvent was removed by
CD
3
OD) d 8.12 (s, 1H), 7.61 (d, J = 3.6 Hz, 1H), 5.92 (dd, J = 2.0,
4.0 Hz, 1H), 5.60 (m, 1H), 4.62 (m, 1H), 4.32 (m, 2H), 4.26 (m,
1
3
1H). C NMR (100 MHz, CD
124.8, 123.9, 78.4, 77.4, 72.7, 67.4, 61.5, 58.8. Anal. Calcd for
: C, 51.43; H, 4.68; N, 19.99. Found: C, 51.67; H,
4.70; N, 20.01.
3
OD) d 150.3, 142.9, 141.2, 125.0,
2
H
2
12 4 3
C H13FN O
2
4
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C. Liu et al. / Bioorg. Med. Chem. xxx (2015) xxx–xxx
5
3
.1.6. (1R,4R,5S)-3-(2-Hydroxyethyl)-4,5-dihydroxy-2-
N, 20.15. Found: C, 55.91; H, 5.91; N, 19.85. HRMS calcd for
C H N O [M+H] , 277.1301, found 277.1292.
13 17 4 3
+
cyclopenten-l-yl]-4-amino-7-fluoroimidazo[4,5-c]pyridine (8b)
Yield: 58% (for two steps), white solid. 1H NMR (400 MHz,
CD
3
OD) d 8.13 (s, 1H), 7.60 (d, J = 3.6 Hz, 1H), 5.80 (dd, J = 1.6,
3.2. X-ray data for compounds 8a, 8b, and 13
3
5
.2 Hz, 1H), 5.56 (m, 1H), 4.55 (d, J = 5.2 Hz, 1H), 4.23 (dt, J = 1.6,
1
3
.2 Hz, 1H), 3.81 (m, 2H), 2.52 (t, J = 6.4 Hz, 2H)
OD) d 150.6, 149.6, 143.3 (d, J = 241 Hz), 142.8,
30.5, 129.3 (d, J = 12 Hz), 126.5 (d, J = 23 Hz), 79.6, 76.4, 69.2,
0.9, 49.2, 33.7. Anal. Calcd for C13 : C, 53.06; H, 5.14; N,
9.04. Found: C, 52.99; H, 5.14; N, 18.87.
C NMR
Crystallographic data (excluding structure factors) for the struc-
ture in this paper have been deposited with the Cambridge
Crystallographic Data Centre with the following deposition num-
bers CCDC 1063211 (13), 1063212 (8a), and 1063213 (8b).
Copies of the data can be obtained, free of charge, on application
to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK, fax: +44
(
100 MHz, CD
3
1
6
1
H
4 3
15FN O
(
0)1223 336033 or e-mail: deposit@ccdc.cam.ac.uk.
3
.1.7. (1R,2S,3R,5R)-3-(4-Amino-6-fluoro-1H-imidazo[4,5-
c]pyridin-1-yl)-5-(hydroxymethyl)cyclopentane-1,2-diol (9a)
Yield: 59% (for two steps), white solid. 1H NMR (600 MHz,
3.3. Antiviral assays
DMSO-d
6
) d 8.12 (s, 1H), 6.58 (br, 2H), 6.43 (s, 1H), 5.00 (d,
These assays are presented in Ref. 14.
3.4. S-Adenosylhomocysteine (AdoHcy) hydrolase assay
This assay is described in Ref. 14.
Acknowledgements
J = 7.0 Hz, 1H), 4.87 (t, J = 5.0 Hz, 1H), 4.74 (d, J = 5.0 Hz, 1H), 4.52
(
2
dd, J = 7.0, 19.2 Hz, 1H), 4.15 (m, 1H), 3.80 (m, 2H), 3.40 (m, 1H),
.26 (m, 1H), 2.06 (m, 1H), 1.69 (m, 1H). 1 C NMR (150.9 MHz,
3
DMSO-d
41.2, 124.6, 78.6 (d, J = 46 Hz), 75.2, 72.2, 62.8, 60.7, 45.2, 28.4.
Anal. Calcd for C12 : C, 51.06; H, 5.36; N, 19.85. Found:
C, 50.88; H, 5.50; N, 19.65.
6
) d 158.7 (d, J = 220 Hz), 150.1 (d, J = 22 Hz), 141.3,
1
4 3
H15FN O
We are grateful to the Molette Fund and Auburn University for
support and to Gloria Kozamin of Microbiotix, Inc. Worcester, MA
3
.1.8. (1R,2S,3R,5R)-3-(4-Amino-6-fluoro-1H-imidazo[4,5-
c]pyridin-1-yl)-5-(2-hydroxyethyl)cyclopentane-1,2-diol (9b)
for the AdoHcy hydrolase assays. We are also indebted to the
Yield: 63% (for two steps), white solid. 1H NMR (400 MHz,
NIAID in vitro assay team for the viral data presented herein.5
CD
3
OD) d 8.17 (s, 1H), 6.46 (s, 1H), 4.58 (m, 1H), 5.77 (m, 1H),
4
2
.25 (dd, J = 6.0, 7.6 Hz, 1H), 3.84 (t, J = 6.0 Hz, 1H), 3.68 (m, 2H),
References and notes
1
3
.46 (m, 1H), 2.15 (m, 1H), 1.93 (m, 1H), 1.68 (m, 1H). C NMR
OD) d 160.9 (d, J = 225 Hz), 151.2 (d, J = 20 Hz),
43.5, 142.3, 125.4, 80.4 (d, J = 45 Hz), 76.8, 76.6, 63.0, 61.6, 41.9,
8.2, 33.5. Anal. Calcd for C13 : C, 52.70; H, 5.78; N,
8.91. Found: C, 52.60; H, 5.70; N, 18.78.
(
100 MHz, CD
3
1.
Campian, M.; Putala, M.; Sebesta, R. Curr. Org. Chem. 2014, 18, 2808.
1
3
1
2. Curran, A.; Ribera, E. Expert Opin. Drug Saf. 2011, 10, 389.
3
4
.
.
Wang, J.; Rawal, R. K.; Chu, C. K. Med. Chem. Nucleic Acids 2011, 1.
4 3
H17FN O
Cooperwood, J. S.; Gumina, G.; Boudinot, G.; Chu, C. K. Nucleoside and
Nucleotide Prodrugs. In Recent Advances in Nucleosides: Chemistry and
Chemotherapy; Chu, C. K., Ed.; Elsevier Science B.V: Amsterdam, 2002; pp
127–128.
3
.1.9. (1S,2R,3S,4R)-4-(4-Amino-6-fluoro-1H-imidazo[4,5-
5.
For example, (a) Das, S. R.; Schneller, S. W. Nucleosides Nucleotides Nucleic Acids
2014, 33, 668; (b) Ye, W.; Schneller, S. W. Bioorg. Med. Chem. 2014, 22, 5315; (c)
Chen, Q.; Liu, C.; Shulyak, T. S.; Schneller, S. W. Tetrahedron 2014, 70, 892; (d)
Liu, C.; Chen, Q.; Yang, M.; Schneller, S. W. Bioorg. Med. Chem. 2013, 21, 359; (e)
Liu, C.; Chen, Q.; Schneller, S. W. Bioorg. Med. Chem. Lett. 2012, 22, 5182; (f) Liu,
C.; Chen, Q.; Schneller, S. W. Tetrahedron Lett. 2011, 52, 4931; (g) Chen, C.; Ye,
W.; Liu, C.; Schneller, S. W. Tetrahedron 2012, 68, 3908.
c]pyridin-1-yl)cyclopen-tane-1,2,3-triol (9c)
Yield: 62% (for two steps), white solid. 1H NMR (400 MHz,
CD
3
OD) d 8.13 (s, 1H), 6.68 (s, 1H), 4.71 (m, 1H), 5.57 (dd, J = 4.4,
8
1
1
7
4
.4 Hz, 1H), 4.14 (m, 1H), 3.94 (d, J = 4.4 Hz, 1H), 2.83 (m, 1H),
1
3
.94 (m, 1H). C NMR (100 MHz, CD
49.7 (d, J = 21 Hz), 142.0, 141.1, 124.2, 79.2 (d, J = 45 Hz), 76.9,
5.9, 73.7, 60.6, 35.3. Anal. Calcd for C11 : C, 49.25; H,
.89; N, 20.89. Found: C, 49.43; H, 4.96; N, 20.85.
3
OD) d 159.2 (d, J = 225 Hz),
6
7
.
.
De Clercq, E. Nucleosides Nucleotides Nucleic Acids 2005, 24, 1395.
De Clercq, E. Nucleosides Nucleotides 1998, 17, 625.
H13FN
4
O
3
8. (a) Herdewijn, P.; Balzarini, J.; De Clercq, E.; Vanderhaeghe, H. J. Med. Chem.
1985, 28, 1385; (b) Borchardt, T.; Keller, T.; Patel-Thombre, U. J. Biol. Chem.
1984, 259, 4353; (c) De Clercq, E. Antimicrob. Agents Chemother. 1985, 28, 84.
9
. Wolfe, S.; Borchardt, T. J. Med. Chem. 1991, 34, 1521.
3
.1.10. (1R,4R,5S)-3-(Hydroxymethyl)-4,5-dihydroxy-2-
1
0. (a) Montgomery, J.; Clayton, S.; Thomas, J.; Shannon, W.; Arnett, G.; Bodner, A.;
Kion, I.; Cantoni, G.; Chiang, P. J. Med. Chem. 1982, 25, 626; (b) Tseng, C.;
Marquez, V.; Fuller, R.; Goldstein, B.; Haines, D.; McPherson, H.; Parsons, J.;
Shannon, W.; Arnett, G. J. Med. Chem. 1989, 32, 1442; (c) Bray, M.; Paragas, J.
Antiviral Res. 2002, 54, 1; (d) Schneller, S. W.; Yang, M. S-
cyclopenten-l-yl]-4-amino-7-methylimidazo[4,5-c]pyridine
10)
To a solution 23 (obtained in Section 3.1.2) in dry THF (20 mL)
was added Pd(Ph P) (100 mg, 0.087 mmol). To this mixture,
AlMe (1.25 mL, 2.0 M in THF, 2.5 mmol) was added dropwise at
(
Adenosylhomocysteine Hydrolase Inhibitors as a Source of Antifilovirus
Agents. In Antiviral Drug Discovery for Emerging Diseases and Bioterrorism
Threats; Terrence, P. F., Ed.; John Willey and Sons: New York, 2005; pp 139–
3
4
3
room temperature. The reaction mixture was then stirred at room
temperature for 1 h followed by heating at reflux for 12 h. The
reaction mixture was allowed to cool to room temperature and
was then diluted with Et
and brine and dried (anhydrous MgSO
152.
11. Chiang, K.; Richards, H.; Cantoni, L. Mol. Pharmacol. 1977, 13, 939.
1
1
1
1
2. (a) Yang, M.; Zhou, J.; Schneller, S. W. Tetrahedron 2006, 62, 1295; (b) Yang, M.;
Zhou, J.; Schneller, S. W. Tetrahedron Lett. 2004, 45, 8981.
3. Obara, T.; Shuto, S.; Saiyo, Y.; Snoeck, R.; Andrei, G.; Balzarini, J.; De Clercq, E. J.
Med. Chem. 1996, 39, 3847.
2
O (30 mL); this was washed with H
2
O
4
). Concentration of the solu-
4. Chen, Q.; Liu, C.; Komazin, G.; Bowlin, T. L.; Schneller, S. W. Bioorg. Med. Chem.
tion in vacuo gave 24 as a dark solid, which was used in the next
step without further purification.
2014, 22, 6961.
5. Ando, T.; Iwata, M.; Zulfiqar, F.; Miyamoto, T.; Nakanishi, M.; Kitade, Y. Bioorg.
Med. Chem. 2008, 16, 3809.
Crude 24 was subjected to the hydrolysis procedure as with
1
9–22 and 28–30 to give 10: yield: 43% (for three steps), white
16. (a) Yang, M.; Schneller, S. W.; Korba, B. J. Med. Chem 2005, 48, 5043; (b) Yang,
M.; Schneller, S. W. Bioorg. Med. Chem. Lett. 2005, 15, 149.
1
solid. H NMR (400 MHz, CD
3
OD) d 8.04 (s, 1H), 7.44 (s, 1H), 5.95
dd, J = 2.0 Hz, 3.6 Hz, 1H), 5.77 (m, 1H), 4.62 (dd, J = 0.8 Hz,
17. Liu, M.; Luo, M.; Mozdziesz, D. E.; Lin, T.; Dutschman, G. E.; Gullen, E. A.; Cheng,
(
Y.; Sartorelli, A. C. Nucleosides Nucleotides Nucleic Acids 2001, 20, 1975.
5
5
1
5
.6 Hz, 1H), 4.34 (dd, J = 2.0 Hz, 4.0 Hz, 2H), 4.12 (dd, J = 4.8 Hz,
18. There was no activity by the target compounds for (host cell): Compounds 8a,
8b and 10 were inactive towards WNV (Vero 76), cowpox (HFF), vaccinia (HEL),
rhinovirus (Hela Ohio-1), adenovirus (A-549), respiratory syncytial virus (Hela/
MA-104), influenza A (H1N1) (MDCK), influenza A (H3N2) (MDCK), Venezuelan
equine encephalitis virus (Vero), PIV (MA-104), and SARS corona (Vero E6);
.6 Hz, 1H), 2.58 (s, 3H). 1 C NMR (62.9 MHz, DMSO-d
51.0, 140.5, 140.4, 139.1, 137.6, 123.4, 106.7, 78.9, 72.5, 65.4,
8.6, 15.2. Anal. Calcd for C13 O: C, 56.15; H, 5.87;
ꢁ0.1 H
3
6
) d 151.2,
H
16
N
4
O
3
2
Please cite this article in press as: Liu, C.; et al. Bioorg. Med. Chem. (2015), http://dx.doi.org/10.1016/j.bmc.2015.07.039

6
C. Liu et al. / Bioorg. Med. Chem. xxx (2015) xxx–xxx
Compounds 7a and b were inactive when assayed against rift valley fever (Vero
6), dengue (Vero), West Nile (Vero 76), vaccinia (HEL), hepatitis C (Ava5),
Venezuelan equine encephalitis virus (Vero), respiratory syncytial virus (Hela/
MA104), herpes virus 1 and 2 (HEL), influenza A (H1N1) (MDCK), polio (LLC-
encephalitis virus (Vero), and respiratory syncytial virus (Hela/MA-104). Target
9c was also inactive versus herpes virus 1 and 2 (HEL), influenza A (H1N1)
(MDCK), polio (LLC-MK clone 7.1), SARS corona (Vero E6), cowpox (HFF),
chikungunya (Vero 76), entero-71 (LLC-MK ), cytomegalovirus (HEL),
7
2
2
MK
2
clone 7.1), SARS corona (Vero E6). Compounds 9a, 9b, and 9c were
pinchinde (Vero), and human papilloma virus (HEK 293).
inactive towards Rift Valley fever (Vero 76), Tacaribe (Vero 76), dengue (Vero),
West Nile (Vero 76), vaccinia (HEL), hepatitis C (Ava5), Venezuelan equine
19. Hagmann, W. K. J. Med. Chem. 2008, 51, 4359.
Please cite this article in press as: Liu, C.; et al. Bioorg. Med. Chem. (2015), http://dx.doi.org/10.1016/j.bmc.2015.07.039