Design and synthesis of N6-substituted-4′-thioadenosine-5′-uronamides as potent and selective human A3 adenosine receptor agonists

Article abstract of DOI:10.1016/j.bmc.2009.10.011

On the basis of a bioisosteric rationale, 4′-thionucleoside analogues of IB-MECA (N⁶-(3-Iodo-benzyl)-9-(5′-methylaminocarbonyl-β-d- ribofuranosyl)adenine), which is a potent and selective A₃ adenosine receptor (AR) agonist, were synt

Full text of DOI:10.1016/j.bmc.2009.10.011

Bioorganic & Medicinal Chemistry 17 (2009) 8003–8011
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Design and synthesis of N6-substituted-40-thioadenosine-50-uronamides
as potent and selective human A3 adenosine receptor agonists
Won Jun Choi a, Hyuk Woo Lee a, Hea Ok Kim a, Moshe Chinn b, Zhan-Guo Gao b, Amit Patel b,
Kenneth A. Jacobson b, Hyung Ryong Moon c, Young Hoon Jung d, Lak Shin Jeong a,
*
a Department of Bioinspired Science and Division of Life and Pharmaceutical Sciences, College of Pharmacy, Ewha Womans University, Seoul 120-750, Republic of Korea
b Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes, and Digestive and Kidney Disease, National Institutes of Health,
Bethesda, MD 20892, USA
c College of Pharmacy and Research Institute for Drug Development, Pusan National University, Busan 609-735, Republic of Korea
d College of Pharmacy, Sungkyunkwan University, Suwon 440-746, Republic of Korea
a r t i c l e i n f o
a b s t r a c t
On the basis of a bioisosteric rationale, 40-thionucleoside analogues of IB-MECA (N6-(3-Iodo-benzyl)-9-
Article history:
(50-methylaminocarbonyl-b-
D
-ribofuranosyl)adenine), which is a potent and selective A3 adenosine
Received 31 August 2009
Revised 5 October 2009
Accepted 6 October 2009
Available online 12 October 2009
receptor (AR) agonist, were synthesized from -gulonic acid
D
c
-lactone. The 40-thio analogue (5h) of IB-
MECA showed extremely high binding affinity (Ki = 0.25 nM) at the human A3AR and was more potent
than IB-MECA (Ki = 1.4 nM). Bulky substituents at the 50-uronamide position, such as cyclohexyl and 2-
methylbenzyl, in this series of 2-H nucleoside derivatives were tolerated in A3AR binding, although small
alkyl analogues were more potent.
Keywords:
A3 adenosine receptor
40-Thionucleosides
Agonist
Ó 2009 Elsevier Ltd. All rights reserved.
Binding affinity
1. Introduction
activity.7 Because IB-MECA 2 is another representative of A3AR
agonists, it would be of great interest to synthesize its 40-thio ana-
The A3 adenosine receptor (AR), which belongs to the family of
G-protein-coupled receptors (GPCRs), is known to be involved in
cell signaling by modulating the levels of cAMP, inositol triphos-
phate (IP3), and diacylglycerol (DAG) through binding of the
endogenous chemical messenger, adenosine.1 Thus, the A3AR has
been regarded as good therapeutic target for the treatment of sev-
eral diseases associated with cell signaling such as cancer, ische-
mia, inflammation, and glaucoma.2
logue and to compare their biological activities and substituent ef-
fects (H vs Cl) at the C2 position. It would be also interesting to
study SAR surrounding the 50-uronamide moiety of the 40-thionu-
cleosides. The A3AR has displayed a moderate tolerance for
sterically bulky substituents at this position, in contrast to the N-
methylamides of the protypical agonists 1 and 2.6b Herein, we
report the synthesis and binding affinity of the series of compound
5 as potent and selective A3AR agonists.
Adenosine has served as a good template for the development
of A3AR ligands. Extensive modification of adenosine resulted in
the discovery of Cl-IB-MECA, 1 (Ki = 1.0 nM for human A3AR)3
and IB-MECA, 2 (Ki = 1.4 nM for human A3AR)4 as potent and selec-
tive A3AR agonists and these are in clinical trials as anticancer
agents5 (Fig. 1). Recently, probing the structure–activity relation-
ship (SAR) of compound 1 on the basis of a bioisosteric rationale
indicated that a 40-thionucleoside could serve as an excellent tem-
plate for the development of A3AR agonists, among which com-
pounds 3 and 4 were discovered as more potent A3AR agonists
(Ki = 0.38 and 0.28 nM, respectively) than Cl-IB-MECA 1.6 Com-
pound 3 also showed potent in vitro as well as in vivo anticancer
2. Results and discussion
The target nucleoside 5 was synthesized from D-gulonic acid c-
lactone, as shown in Scheme 1.
D
-Gulonic acid c-lactone was smoothly converted to the
glycosyl donor 6 according to our previously published procedure.6
Condensation of 6 with 6-chloropurine in the presence of TMSOTf
afforded the 6-chloropurine derivative 7 (53%) and its
a-anomer
(5.4%).8 The anomeric configuration of 7 was easily confirmed by
an NOE effect between 10-H and 40-H. Irradiation on 10-H of
compound 6 gave NOE effect on its 40-H, indicating b-anomer,
but no NOE effect was observed on the same experiment in the
case of its
a
-anomer.8 Treatment of 7 with methyl amine and
* Corresponding author. Tel.: +82 2 3277 3466; fax: +82 2 3277 2851.
E-mail address: lakjeong@ewha.ac.kr (L.S. Jeong).
3-iodobenzylamine gave the N6-methyladenine derivative 8 and
0968-0896/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2009.10.011

8004
W. J. Choi et al. / Bioorg. Med. Chem. 17 (2009) 8003–8011
NHR1
HN
I
N
N
N
N
N
N
SAR
MeHN
O
MeHN
O
N
N
X
Cl
X = Cl
O
S
OH OH
OH OH
1 (X = Cl); Cl-IB-MECA
2 (X = H); IB-MECA
3 (R1 = 3-iodobenzyl)
4 (R1 = methyl)
X = H
SAR
NHR2
N
N
N
R3HN
O
N
H
S
OH OH
5
R2 = methyl or 3-iodobenzyl
R3 = alkyl, cycloalkyl, or arylalkyl
Figure 1.
Cl
N
N
O
S
ref. 6
a
O
BzO
N
O
N
BzO
S
HO
HO
OH OH
O
O
O
O
D-Gulonic acid γ-lactone
6
7
b
NHR2
NHR2
NHR2
N
N
N
N
N
N
N
N
N
c,d
e
N
BzO
N
N
HO
BzO
S
S
S
O
O
TBSO OTBS
12 (R2 = methyl) (63%)
TBSO OTBS
10 (R2 = methyl)
8 (R2 = methyl) (74%)
13 (R2 = 3-iodobenzyl) (82%)
11 (R2 = 3-iodobenzyl)
9 (R2 = 3-iodobenzyl) (88%)
Scheme 1. Reagents and conditions: (a) 6-chloropurine, TMSOTf, ClCH2CH2Cl, rt to 80 °C; (b) R2NH2, Et3N, EtOH, rt; (c) 80% AcOH, 70 °C; (d) TBSOTf, pyridine, 50 °C; (e)
NaOMe, MeOH.
N6-(3-iodobenzyl)adenine derivative 9, respectively. For the con-
version of 40-hydroxymethyl group into various 50-uronamides,
the 20,30-isopropylidene group was first changed to the 20,30-di-
O-TBS group, because the removal of the 20,30-isopropylidene
group at the final step resulted in the deglycosylation. Treat-
ment of 8 and 9 with 80% acetic acid followed by protection
of the resulting diol with the TBS group yielded 10 and 11,
respectively. Removal of the benzoyl group in 10 and 11 with
sodium methoxide gave the 40-hydroxymethyl derivatives 12
and 13, respectively.

W. J. Choi et al. / Bioorg. Med. Chem. 17 (2009) 8003–8011
8005
NHR2
NHR2
NHR2
N
N
N
N
N
N
N
N
N
N
O
a
O
N
HO
R3HN
b,c
N
HO
S
S
S
TBSO OTBS
OH OH
TBSO OTBS
5a-w
14 (R2 = methyl)
12 (R2 = methyl)
R2 = methyl or 3-iodobenzyl
15 (R2 = 3-iodobenzyl)
13 (R2 = 3-iodobenzyl)
R3 = alkyl, cycloalkyl, or arylakyl
Scheme 2. Reagents: (a) PDC, DMF; (b) R3NH2, EDC, HOBt, DIPEA, CH2Cl2; (c) TBAF, THF.
Treatment of 12 and 13 with PDC in DMF afforded the carbox-
ylic acid derivatives 14 and 15, respectively (Scheme 2). Coupling
of the acids 14 and 15 with various primary amines in the presence
of EDC and HOBt yielded various 50-uronamides 5a–w after the re-
moval of the TBS group.
Radioligand binding assay was performed using adherent CHO
(Chinese hamster ovary) cells stably transfected with cDNA encod-
ing the human ARs.9 Bindings at the human ARs were carried out
using [3H]R-PIA for A1AR, [3H]CGS21680 for A2AAR, and [125I]I-
AB-MECA for A3AR as radioligands. In cases of weak binding, the
percent inhibition of radioligand binding to the human ARs was
was also revealed that small alkyl or cycloalkyl substituents on
the 50-uronamide were essential for optimal binding affinity. Bulky
substituents on the 50-uronamide, such as cyclohexyl and 2-meth-
ylbenzyl, were tolerated, but less potent in A3AR binding. We be-
lieve that compound 5h has promise to be developed as a
clinically useful agent.
3. Experimental section
1H NMR spectra (CDCl3, CD3OD, or DMSO-d6) were recorded on
Varian Unity Inova 400 MHz. Chemical shifts were reported in
ppm units with TMS as the internal standard. 13C NMR spectra
(CDCl3, CD3OD, or DMSO-d6) were recorded on Varian Unity Inova
100 MHz. Analytical thin-layer chromatography (TLC) was per-
formed on Merck Silica Gel 60F-254 glass plates. Optical rotations
were determined on Jasco III in methanol. UV spectra were recorded
on U-3000 made by Histachi in methanol. Elementary analyses were
measured on EA1110. The crude products were purified using a
Silica Gel 60 (230–400 mesh, Merck). Reagents were purchased from
Aldrich Chemical Company. All the anhydrous solvents were dis-
tilled over CaH2 or P2O5 or Na/benzophenone prior to the reaction.
determined at 1
clase in comparison to the full agonist Cl-IB-MECA, 1) of the human
A3AR was determined at 1 M.
lM. Percent activation (inhibition of adenylate cy-
l
Most of the synthesized compounds showed very high binding
affinity at the human A3AR with high selectivity in comparison to
other subtypes (Table 1). When compared with the 40-oxonucleo-
side, IB-MECA (2) (Ki = 1.4 nM), the corresponding 40-thionucleo-
side, thio-IB-MECA (5h) exhibited higher binding affinity at the
human A3AR (Ki = 0.25 nM) as well as higher selectivity over other
subtypes, indicating that thio-IB-MECA (5h) has the potential to be
developed as a clinical candidate as IB-MECA (2). A similar trend
was observed between Cl-IB-MECA (1) (Ki = 1.0 nM) and thio-Cl-
IB-MECA (3) (Ki = 0.38 nM). However, thio-IB-MECA (5h) was
found to be less selective (81- vs 508-fold) for the human A3AR
in comparison to at the human A1AR than thio-Cl-IB-MECA (3).
This result indicated that substitution of the 2-H atom with more
hydrophobic 2-Cl substituent increased the A3 AR selectivity.10 It
should be noted that thio-IB-MECA (5h) showed the best binding
affinity at the human A3AR among 40-thionucleosides synthesized
so far. This compound also showed very high binding affinity
(Ki = 1.86 0.36 nM) at the rat A3AR. In the N6-methyladenine
series, the binding affinity at the human A3AR of the
synthesized 50-uronamides was dependent on the 50-N substitu-
tion in the following order: ethyl = cyclopentyl > cyclobutyl >
cyclopropylmethyl > methyl > cyclopropyl > 3-iodobenzyl, indicat-
ing that alkyl and cycloalkyl derivatives 5a–f showed better bind-
ing affinity (Ki = 0.97–2.16 nM) than arylalkyl derivative 5g
(Ki = 15.6 nM). A similar trend was observed in the N6-(3-iodoben-
zyl)adenine series, except that the N6-(3-iodobenzyl)adenine
derivatives showed slightly better binding affinity at the human
A3AR and generally were more selective versus the human A1AR
than the N6-methyladenine derivatives.
3.1. Benzoic acid (3aS,4R,6R,6aR)-6-(6-chloro-purin-9-yl)-2,2-
dimethyl-tetrahydro-thieno[3,4-d][1,3]dioxol-4-ylmethyl ester
(7)8
To a suspension of 6-chloropurine (3.36 g, 21.69 mmol) in a
solution of dry CH3CN (20 mL) and 1,2-dichloroethane (10 mL)
were added Et3N (2.19 g, 21.69 mmol) and TMSOTf (9.64 g,
43.38 mmol), and the mixture was stirred at room temperature un-
til the solution was clear. A solution of sulfoxide 6 (3.36 g,
10.85 mmol) in dry 1,2-dichloroethane (10 mL) was added to the
resulting solution in one shot at room temperature. An additional
amount of Et3N (2.19 g, 21.69 mmol) was added to the reaction
mixture to initiate the Pummerer reaction. The reaction mixture
was stirred under reflux at 80 °C for 4 d, during which time the ini-
tially formed N-3 isomer was converted to N-9 isomer. The reac-
tion mixture was partitioned between EtOAc and aqueous
saturated NaHCO3 solution, and the organic layer was washed with
brine, dried (MgSO4), filtered and evaporated. The residue was
purified by flash silica gel column chromatography (hexane/
EtOAc = 5:1) to give 7 (2.57 g, 53%), whose spectral data were iden-
tical with those of authentic sample.8
The most potent and selective compound 5h was a full agonist
in an assay of human A3 adenosine receptor-mediated inhibition of
cyclic AMP in transfected CHO cells, as previously observed for
compounds 1–4.
3.2. General procedure for the preparation of the N6-substituted
nucleosides 8 and 9
In summary, we have established SARs of bioisosteric 40-thio
analogues of potent and selective A3AR agonist, IB-MECA (2). From
this study, thio-IB-MECA (5h) was discovered as being among the
most potent A3 AR agonists and more potent than IB-MECA (2). It
To a solution of 7 in anhydrous EtOH (20 mL/mmol) were added
triethylamine (3.0 equiv) and appropriate amine (1.2 equiv). After
being stirred at room temperature for 24 h, the reaction mixture
was evaporated. The residue was purified by silica gel column

Table 1
Potency of 40-thioadenosine-50-uronamide derivatives 5a–w at human A1, A2A, and A3ARs and maximal agonist effects at human A3ARs expressed in CHO cellsa
NHR2
N
N
R3HN
O
N
N
Y
X
OH OH
Compound no.
R2
R3
Ki (hA1AR) nMa or % inhibition at 1
lM
Ki (hA2AAR) nMa or % inhibition at 1
lM
Ki (hA3AR) nMa or % inhibition at 1
lM
1 (X = O, Y = Cl)
2 (X = O, Y = H)
3 (X = S, Y = Cl)
4 (X = S, Y = Cl)
5a (X = S, Y = H)
5b (X = S, Y = H)
5c (X = S, Y = H)
5d (X = S, Y = H)
5e (X = S, Y = H)
5f (X = S, Y = H)
5g (X = S, Y = H)
5h (X = S, Y = H)
5i (X = S, Y = H)
5j (X = S, Y = H)
5k (X = S, Y = H)
5l (X = S, Y = H)
5m (X = S, Y = H)
5n (X = S, Y = H)
5o (X = S, Y = H)
5p (X = S, Y = H)
5q (X = S, Y = H)
5r (X = S, Y = H)
5s (X = S, Y = H)
5t (X = S, Y = H)
5u (X = S, Y = H)
5v (X = S, Y = H)
5w (X = S, Y = H)
3-Iodobenzyl
3-Iodobenzyl
3-Iodobenzyl
Methyl
Methyl
Methyl
Methyl
Methyl
Methyl
Methyl
Methyl
Methyl
Methyl
Methyl
Methyl
Ethyl
Cyclopropyl
Cyclopropylmethyl
Cyclobutyl
Cyclopentyl
3-Iodobenzyl
Methyl
222 22
51
5360 2470
2900
223 36
20%
35 8%
20%
1.4 0.3
1.0
193 46
1330 240
69.5 5.2
4.83 0.20
6.58 0.60
33.1 1.6
6.27 0.50
48.6 14.2
24 1%
20.2 2.9
5.4 0.3
9.27 0.83
159 40
23.6 4.2
28 14%
25 4%
25 3%
18 5%
4070 560
15 3%
34 1%
12 7%
20 6%
20%
17 0%
0.38 0.07
0.28 0.09
1.19 0.23
0.97 0.23
2.16 0.24
1.35 0.08
1.04 0.05
0.97 0.07
15.6 5.6
0.25 0.06
0.42 0.22
3.03 0.23
2.16 0.29
1.17 0.16
35.4 10.5
61.1 17.6
144 33
161 16
38 5%
108 18
45 1%
27 10%
475 144
57.6 6.9
15.2 2.6
1600 80
122 62
24 7%
35 8%
44 1%
26 10%
31 1%
37 0%
28 9%
23 8%
20 8%
11%
Methyl
3-Iodobenzyl
3-Iodobenzyl
3-Iodobenzyl
3-Iodobenzyl
3-Iodobenzyl
3-Iodobenzyl
3-Iodobenzyl
3-Iodobenzyl
3-Iodobenzyl
3-Iodobenzyl
3-Iodobenzyl
3-Iodobenzyl
3-Iodobenzyl
3-Iodobenzyl
3-Iodobenzyl
3-Iodobenzyl
Ethyl
Cyclopropyl
Cyclopropylmethyl
Cyclobutyl
Cyclohexyl
3-Fluorobenzyl
3-Chlorobenzyl
2-Methylbenzyl
3-Methylbenzyl
4-Methylbenzyl
2-Methoxybenzyl
2-Ethoxybenzyl
31.0 7.1
94.9 37.3
135 55
97.0 51.2
113
2
a-Naphthylmethyl
1200
433 141
116 48
2-Phenylethyl
1,1-Diphenylethyl
38 8%
a
All AR experiments were performed using adherent CHO cells stably transfected with cDNA encoding the human or rat ARs. Binding was carried out as described in ref. 6 using as radioligand [3H]R-PIA or [3H]NECA at the
human A1AR and [3H]CGS 21680 at the human A2AAR. Values from the present study are expressed as mean s.e.m., n = 3–5.

W. J. Choi et al. / Bioorg. Med. Chem. 17 (2009) 8003–8011
8007
chromatography (hexane/ethyl acetate = 1:1) to give the N6-substi-
tuted nucleosides 8 and 9.
3.3.2. 9-[(20,30-Bis-tert-butyl-dimethyl-silanyloxy-50-hydroxyme-
thyl)-40-thio-b-
-ribofuranosyl]-6-(3-iodobenzylamino)purine (13)
D
Yield 82%; white solid; UV (MeOH) kmax 270 nm (pH 7); 1H NMR
(CDCl3) d 0.01 (m, 12H, 4 ꢁ Si–CH3), 0.62 (s, 9H, C(CH3)3), 0.83 (s,
9H, C(CH3)3), 3.27 (dd, 1H, J = 5.6, 11.7 Hz, 2-H), 3.74 (m, 1H,
HOCHH), 3.86 (m, 1H, HOCHH), 4.14 (dd, 1H, J = 5.7, 11.5 Hz, 30-
H), 4.63 (br s, 2H, N–CH2), 5.20 (dd, 1H, J = 6.3, 11.9 Hz, 20-H),
5.60 (d, 1H, J = 4.6 Hz, 10-H), 5.93 (br s, 1H, OH), 6.93 (t, 1H,
J = 7.7 Hz, aromatic H), 7.13 (s, 1H, NH), 7.58 (d, 1H, J = 7.5 Hz, aro-
matic H), 7.60 (d, 1H, J = 7.8 Hz, aromatic H), 7.67 (s, 1H, aromatic
H), 8.01 (s, 1H, H-2), 8.28 (s, 1H, H-8); FAB-MS m/z 728 (M+). Anal.
Calcd for C29H46IN5O3SSi2: C, 47.86; H, 6.37; N, 9.62; S, 4.41. Found:
C, 48.02; H, 6.43; N, 9.65; S, 4.39.
3.2.1. 6-Methylamino-9-[(50-O-benzoyl-20,30-O-isopropylidene)-
40-thio-b-
D-ribofuranosyl]purine (8)
Compound 8 was prepared using methylamineꢀHCl: yield 74%;
white foam; UV (MeOH) kmax 271 nm (pH 7); 1H NMR (CDCl3) d
1.40 (s, 3H, CH3), 1.68 (s, 3H, CH3), 3.10 (d, 3H, J = 3.0 Hz, N–
CH3), 4.12 (td, 1H, J = 2.7, 7.8 Hz, 40-H), 4.60 (dd, 1H, J = 6.7,
11.4 Hz, BzOCHH), 4.63 (dd, 1H, J = 7.8, 11.5 Hz, BzOCHH), 4.99
(dd, 1H, J = 2.9, 5.6 Hz, 30-H), 5.03 (dd, 1H, J = 1.9, 5.6 Hz, 20-H),
6.01 (d, 1H, J = 1.9 Hz, 10-H), 6.31 (br s, 1H, NH), 7.37–7.88 (m,
5H, Ph), 8.46 (s, 1H, H-8), 8.57 (s, 1H, H-2); FAB-MS m/z 442
(M++1). Anal. Calcd for C21H23N5O4S: C, 57.13; H, 5.25; N, 15.86;
S, 7.26. Found: C, 57.20; H, 5.28; N, 15.75; S, 7.32.
3.4. General procedure for the preparation of the N6-substitu-
ted-40-thioadenosine-50-uronamides 5a–w
3.2.2. 6-(3-Iodo-benzylamino)-9-[(50-O-benzoyl-20,30-O-isopro-
pylidene)-40-thio-b-
D-ribofuranosyl]purine (9)
To a stirred solution of 40-hydroxymethyl analogue (1 mmol, 12
and 13) in dry DMF (10 mL) was added pyridinium dichromate
(10.0 equiv) and the reaction mixture was stirred at room temper-
ature for 20 h. Water (50 mL) was added to the reaction mixture,
and stirred at room temperature for 1 h. The precipitate was fil-
tered and the filter cake was washed with water many times and
dried under high vacuum to give the acid (14 and 15) as a brownish
solid, which was used in the next step without further purification.
To a solution of 14 and 15 (1 mmol) in CH2Cl2 (20 mL) were added
EDC (1.5 equiv), HOBt (1.5 equiv), appropriate amine (1.5 equiv),
and DIPEA (3.0 equiv) and the mixture was stirred at room temper-
ature for 15 h. The reaction mixture was evaporated and the residue
was purified by a silica gel column chromatography (hexane/
EtOAc = 10:1–5:1) to give the corresponding silyl amide as a white
foam. To a stirred solution of silyl amide (1 mmol) in THF (5 mL)
was added TBAF (2.5 equiv) and the reaction mixture was stirred
at room temperature for 1 h. The solvent was evaporated and the
resulting residue was purified by silica gel column chromatography
(CH2Cl2/MeOH = 10:1) to give 5a–w as white solids.
Compound 9 was prepared using 3-iodo-benzylamine: yield
88%; white foam; UV (MeOH) kmax 272 nm (pH 7); 1H NMR (CDCl3)
d
1.23 (s, 3H, CH3), 1.37 (s, 3H, CH3), 4.06 (td, 1H, J = 2.4, 7.3 Hz, 40-
H), 4.46 (dd, 1H, J = 6.8, 11.4 Hz, BzOCHH), 4.53 (dd, 1H, J = 2.7,
11.4 Hz, BzOCHH), 4.73 (d, 2H, J = 5.8 Hz, N–CH2), 4.89 (dd, 1H,
J = 2.4, 5.6 Hz, 30-H), 5.02 (dd, 1H, J = 2.0, 5.6 Hz, 20-H), 5.96 (s,
1H, 10-H), 6.59 (br s, 1H, NH), 7.11–7.84 (m, 9H, aromatic H),
8.52 (s, 1H, H-8), 8.58 (s, 1H, H-2); FAB-MS m/z 644 (M++1). Anal.
Calcd for C27H26IN5O4S: C, 50.40; H, 4.07; N, 10.88; S, 4.98. Found:
C, 50.33; H, 4.21; N, 10.90; S, 4.88.
3.3. General procedure for the preparation of the 40-hydroxyme-
thyl analogues 12 and 13
A solution of per mmol of N6-substituted nucleosides (8 and 9)
in 80% aqueous AcOH solution (30 mL) was stirred at 70 °C for 12 h.
The solvent was removed under reduced pressure and the mixture
was neutralized with methanolic ammonia. After evaporation, the
residue was purified by silica gel column chromatography (CH2Cl2/
MeOH = 10:1) to give diol as a white foam.
To a stirred solution of per mmol of diol in dry pyridine (20 mL)
was added a solution of TBDMSOTf (5.0 equiv) dropwise and the
reaction mixture was stirred at 50 °C for 5 h. The mixture was par-
titioned between CH2Cl2 and H2O and the organic layer was
washed with water, aqueous NaHCO3 solution, water, brine, dried
over anhydrous MgSO4, and evaporated. The crude disilyl ether
was used in the next step without further purification.
To a stirred solution of per mmol of disilyl ether in anhydrous
methanol (30 mL) was added sodium methoxide (1.5 equiv) and
the mixture was stirred at room temperature for 4 h. After being
neutralized with glacial acetic acid, the mixture was evaporated.
The resulting residue was purified by silica gel column chromatog-
raphy (hexane/ethyl acetate = 1:1) to gave 40-hydroxymethyl ana-
logues 12 and 13, respectively.
3.4.1. N6-Methyl-9-(50-methylaminocarbonyl-40-thio-b-
D-ribofur-
anosyl)adenine (5a)
Compound 5a was prepared using methylamineꢀHCl: yield 70%;
white solid; ½a 2D5
ꢃ24.0 (c 0.13, MeOH); UV (MeOH) kmax 270 nm
ꢂ
(pH 7); 1H NMR (DMSO-d6) d 2.78 (d, 3H, J = 4.0 Hz, N–CH3), 2.90
(d, 3H, J = 4.5 Hz, N–CH3), 3.76 (d, 1H, J = 4.2 Hz, 40-H), 4.35 (dd,
1H, J = 4.6, 8.0 Hz, 30-H), 4.52 (dd, 1H, J = 4.8, 8.5 Hz, 20-H), 5.42
(d, 1H, J = 5.4 Hz, exchangeable with D2O, OH), 5.70 (d, 1H,
J = 5.1 Hz, exchangeable with D2O, OH), 5.80 (d, 1H, J = 5.4 Hz, 10-
H), 7.98 (s, 1H, H-2), 8.32 (br q, 2H, exchangeable with D2O, NH,
NH), 8.54 (s, 1H, H-8); 13C NMR (DMSO-d6) d 51.0, 55.3, 64.3,
70.2, 75.4, 78.2, 118.5, 139.9, 149.5, 150.3, 152.5, 174.4; FAB-MS
m/z 325 (M++1). Anal. Calcd for C12H16N6O3S: C, 44.44; H, 4.97;
N, 25.91; S, 9.89. Found: C, 44.52; H, 5.03; N, 25.98; S, 9.86.
3.4.2. 9-(50-Ethylaminocarbonyl-40-thio-b- -ribofuranosyl)-N6-
D
methyladenine (5b)
3.3.1. 9-[(20,30-Bis-tert-butyl-dimethyl-silanyloxy-50-hydroxyme-
Compound 5b was prepared using ethylamineꢀHCl: yield 65%;
white solid; ½a 2D5
ꢃ48.2 (c 0.15, MeOH); UV (MeOH) kmax 270 nm
ꢂ
thyl)-6-methylamino-40-thio-b-
D-ribofuranosyl]purine (12)
Yield 63%; white solid; UV (MeOH) kmax 270 nm (pH 7); 1H NMR
(CDCl3) d 0.01 (m, 12H, 4 ꢁ Si–CH3), 0.60 (s, 9H, C(CH3)3), 0.85 (s,
9H, C(CH3)3), 3.10 (br s, 3H, N–CH3), 3.20 (dd, 1H, J = 5.6, 11.7 Hz,
40-H), 4.20 (m, 1H, 30-H), 4.45 (dd, 1H, J = 5.8, 11.7 Hz, HOCHH),
4.75 (m, 1H, 20-H), 4.87 (dd, 1H, J = 6.3, 11.7 Hz, HOCHH), 5.43 (d,
1H, J = 4.6 Hz, 10-H), 5.65 (br s, 1H, OH), 8.00 (s, 1H, H-2), 8.03
(br s, 1H, NH), 8.23 (s, 1H, H-8); FAB-MS m/z 526 (M++1). Anal.
Calcd for C23H43N5O3SSi2: C, 52.53; H, 8.24; N, 13.32; S, 6.10.
Found: C, 52.40; H, 8.35; N, 13.22; S, 6.14.
(pH 7); 1H NMR (DMSO-d6) d 1.07 (t, 3H, J = 7.2 Hz, CH2CH3), 2.55
(d, 3H, J = 4.5 Hz, N–CH3), 3.11 (m, 2H, N–CH2), 3.76 (d, 1H,
J = 4.0 Hz, 40-H), 4.04 (dd, 1H, J = 4.0, 7.5 Hz, 30-H), 4.48 (dd, 1H,
J = 5.5, 8.0 Hz, 20-H), 5.54 (d, 1H, J = 5.0 Hz, exchangeable with
D2O, OH), 5.68 (d, 1H, J = 5.2 Hz, exchangeable with D2O, OH),
5.80 (d, 1H, J = 5.5 Hz, 10-H), 8.05 (s, 1H, H-2), 8.30 (br s, 2H,
exchangeable with D2O, NH, NH), 8.53 (s, 1H, H-8); 13C NMR
(DMSO-d6) d 24.3, 48.9, 50.2, 61.3, 73.2, 74.4, 78.5, 116.3, 140.5,
150.8, 151.5, 152.5, 173.4; FAB-MS m/z 339 (M++1). Anal. Calcd

8008
W. J. Choi et al. / Bioorg. Med. Chem. 17 (2009) 8003–8011
for C13H18N6O3S: C, 46.14; H, 5.36; N, 24.84; S, 9.48. Found: C,
46.25; H, 5.30; N, 25.00; S, 9.56.
1H, H-2), 8.33 (br s, 1H, exchangeable with D2O, NH), 8.43 (br s,
1H, J = 4.5 Hz, exchangeable with D2O, NH), 8.53 (s, 1H, H-8); 13C
NMR (CD3OD) d 23.4, 24.5, 31.7, 32.5, 38.3, 48.5, 48.6, 65.3, 74.5,
80.4, 129.3, 145.3, 148.5, 153.0, 155.4, 175.2; FAB-MS m/z
379(M++1). Anal. Calcd for C16H22N6O3S: C, 50.78; H, 5.86; N,
22.21; S, 8.47. Found: C, 50.75; H, 5.53; N, 22.45; S, 8.68.
3.4.3. 9-(50-Cyclopropylaminocarbonyl-40-thio-b-
N6-methyladenine (5c)
D-ribofuranosyl)-
Compound 5c was prepared using cyclopropyl amine: yield
61%; white solid; ½a D25
ꢃ15.8 (c 0.15, MeOH); UV (MeOH) kmax
ꢂ
269.0 nm (pH 7); 1H NMR (DMSO-d6) d 0.04 (m, 2H, cyclopropyl-
CH2), 0.27 (m, 2H, cyclopropyl-CH2), 2.65 (m, 1H, NCH), 2.93 (d,
3H, J = 4.5 Hz, N–CH3), 3.65 (d, 1H, J = 4.0 Hz, 40-H), 4.45 (dd, 1H,
J = 4.5, 8.0 Hz, 30-H), 4.52 (dd, 1H, J = 5.0, 8.5 Hz, 20-H), 5.40 (d,
1H, J = 4.0 Hz, exchangeable with D2O, OH), 5.59 (d, 1H, J = 4.8 Hz,
exchangeable with D2O, OH), 5.85 (d, 1H, J = 7.8 Hz, 10-H), 8.05 (s,
1H, H-2), 8.35 (br s, 1H, exchangeable with D2O, NH), 8.38 (br s,
1H, exchangeable with D2O, NH), 8.57 (s, 1H, H-8); 13C NMR
(DMSO-d6) d 6.1, 6.8, 24.0, 48.5, 50.6, 58.4, 75.4, 78.3, 114.8,
148.3, 150.2, 152.5, 155.3, 174.5; FAB-MS m/z 351 (M++1). Anal.
Calcd for C14H18N6O3S: C, 47.99; H, 5.18; N, 23.98; S, 9.15. Found:
C, 48.12; H, 5.25; N, 24.05; S, 9.23.
3.4.7. 9-[(50-(3-Iodo-benzylaminocarbonyl)-40-thio-b-
anosyl)]-N6-methyladenine (5g)
D-ribofur-
Compound 5g was prepared using 3-iodo-benzylamine: yield
54%; white solid; ½a D25
ꢃ23.0 (c 0.10, MeOH); UV (MeOH) kmax
ꢂ
270 nm (pH 7); 1H NMR (DMSO-d6) d 2.94 (d, 3H, J = 4.5 Hz, N–
CH3), 3.87 (d, 1H, J = 4.3 Hz, 40-H), 4.25 (dd, 1H, J = 4.4, 8.8 Hz, 30-
H), 4.56 (dd, 1H, J = 4.9, 8.8 Hz, 20-H), 4.68 (d, 2H, J = 3.5 Hz, NH2),
5.56 (d, 1H, J = 4.0 Hz, exchangeable with D2O, OH), 5.80 (d, 1H,
J = 4.8 Hz, exchangeable with D2O, OH), 5.82 (d, 1H, J = 7.8 Hz, 10-
H), 7.14–7.76 (m, 4H, aromatic H), 7.98 (br s, 1H, exchangeable
with D2O, NH), 8.05 (br s, 1H, J = 4.5 Hz, exchangeable with D2O,
NH), 8.25 (s, 1H, H-2), 8.53 (s, 1H, H-8); 13C NMR (CD3OD) d 45.3,
50.1, 53.3, 65.4, 78.8, 85.4, 99.4, 125.3, 127.5, 128.4, 130.2, 135.0,
144.2, 145.3, 148.5, 152.3, 156.8, 173.5; FAB-MS m/z 527 (M++1).
Anal. Calcd for C18H19IN6O3S: C, 41.07; H, 3.64; N, 15.97; S, 6.09.
Found: C, 41.35; H, 3.66; N, 16.12; S, 6.24.
3.4.4. 9-(50-Cyclopropylmethylaminocarbonyl-40-thio-b-
furanosyl)-N6-methyladenine (5d)
D-ribo-
Compound 5d was prepared using cyclopropyl methylamineꢀHCl:
yield 68%; white solid; ½a D25
ꢃ15.8 (c 0.15, MeOH); UV (MeOH) kmax
ꢂ
270 nm (pH 7); 1H NMR (DMSO-d6) d 0.05 (m, 2H, cyclopropyl-
CH2), 0.35 (m, 2H, cyclopropyl-CH2), 0.78 (m, 1H, cyclopropyl-
CH), 2.93 (d, 3H, J = 4.0 Hz, N–CH3), 3.03 (t, 2H, J = 4.5, 7.8 Hz,
N–CH2), 3.77 (d, 1H, J = 4.0 Hz, 40-H), 4.27 (dd, 1H, J = 4.5, 9.0 Hz,
30-H), 4.45 (dd, 1H, J = 4.6, 8.8 Hz, 20-H), 5.46 (d, 1H, J = 4.3 Hz,
exchangeable with D2O, OH), 5.68 (d, 1H, J = 4.8 Hz, exchangeable
with D2O, OH), 5.77 (d, 1H, J = 7.8 Hz, 10-H), 8.12 (s, 1H, H-2),
8.34 (br s, 1H, exchangeable with D2O, NH), 8.43 (br s, 1H,
exchangeable with D2O, NH), 8.53 (s, 1H, H-8); 13C NMR (CD3OD)
d 2.5, 2.7, 10.8, 43.2, 46.3, 58.3, 60.5, 72.3, 75.6, 120.5, 148.7,
150.1, 153.4, 156.5, 173.5; FAB-MS m/z 365 (M++1). Anal. Calcd
for C15H20N6O3S: C, 49.44; H, 5.53; N, 23.06; S, 8.80. Found: C,
49.40; H, 5.55; N, 22.98; S, 8.87.
3.4.8. N 6 -(3-Iodo-benzyl)-9-(50-methylaminocarbonyl-40-thio-
b-D
-ribofuranosyl)adenine (5h)
Compound 5h was prepared using methylamineꢀHCl: yield 53%;
white solid; ½a 2D5
ꢃ20.5 (c 0.15, MeOH); UV (MeOH) kmax 270 nm
ꢂ
(pH 7); 1H NMR (DMSO-d6) d 2.70 (d, 3H, J = 4.0 Hz, N–CH3), 3.82
(d, 1H, J = 4.5 Hz, 40-H), 4.37 (br dd, 1H, J = 4.5, 8.4 Hz, 30-H), 4.57
(m, 1H, 20-H), 4.65 (d, 2H, J = 5.7 Hz, N–CH2), 5.62 (d, 1H,
J = 5.5 Hz, exchangeable with D2O, OH), 5.80 (d, 1H, J = 5.1 Hz,
exchangeable with D2O, OH), 5.88 (d, 1H, J = 5.4 Hz, 10-H), 7.13 (t,
1H, J = 7.8 Hz, aromatic H), 7.35 (d, 1H, J = 7.6 Hz, aromatic H),
7.60 (d, 1H, J = 7.8 Hz, aromatic H), 7.73 (s, 1H, aromatic H), 8.26
(br s, 1H, H-2), 8.54 (s, 1H, H-8), 8.55 (br s, 1H, exchangeable with
D2O, NH); 13C NMR (DMSO-d6) d 42.0, 51.5, 60.3, 64.5, 76.0, 78.2,
118.8, 126.4, 133.5, 135.3, 136.0, 140.3, 141.5, 149.9 , 150.4,
153.0, 154.7, 170.3; FAB-MS m/z 527 (M++1). Anal. Calcd for
C18H19IN6O3S: C, 41.07; H, 3.64; N, 15.97; S, 6.09. Found: C,
41.35; H, 3.66; N, 16.12; S, 6.24.
3.4.5. 9-(50-Cyclobutylaminocarbonyl-40-thio-b-
N6-methyladenine (5e)
D-ribofuranosyl)-
Compound 5e was prepared using cyclobutylamine: yield 59%;
white solid; ½a 2D5
ꢃ24.0 (c 0.10, MeOH); UV (MeOH) kmax 270 nm
ꢂ
(pH 7); 1H NMR (DMSO-d6) d 1.71 (m, 2H, cyclobutyl-CH2), 1.96
(m, 2H, cyclobutyl-CH2), 2.25 (m, 2H, cyclobutyl-CH2), 2.98 (d,
3H, J = 4.5 Hz, N–CH3), 3.84 (m, 1H, cyclopropyl-CH), 4.01 (d, 1H,
J = 4.0 Hz, 40-H), 4.47 (dd, 1H, J = 4.7, 8.8 Hz, 30-H), 4.54 (dd, 1H,
J = 4.5, 8.0 Hz, 20-H), 5.63 (d, 1H, J = 4.5 Hz, exchangeable with
D2O, OH), 5.83 (d, 1H, J = 4.8 Hz, exchangeable with D2O, OH),
5.90 (d, 1H, J = 8.0 Hz, 10-H), 8.21 (s, 1H, H-2), 8.34 (br s, 1H,
exchangeable with D2O, NH), 8.43 (br s, 1H, exchangeable with
D2O, NH), 8.53 (s, 1H, H-8); 13C NMR (CD3OD) d 16.3, 32.5, 33.2,
35.3, 40.3, 42.8, 65.4, 75.3, 76.5, 135.4, 145.3, 147.8, 153.4, 155.0,
175.4; FAB-MS m/z 365 (M++1). Anal. Calcd for C15H20N6O3S: C,
49.44; H, 5.53; N, 23.06; S, 8.80. Found: C, 49.51; H, 5.49; N,
23.10; S, 8.78.
3.4.9. 9-(50-Ethylaminocarbonyl-4-thio-b- -ribofuranosyl)-N6-
D
(3-iodo-benzyl)adenine (5i)
Compound 5i was prepared using ethylamineꢀHCl: yield 66%;
white solid;
½ ꢂ
a 2D0
ꢃ45.6 (c 0.15, MeOH); UV (MeOH) kmax
273.0 nm (pH 7); 1H NMR (DMSO-d6) d 1.09 (t, 3H, J = 7.0 Hz,
CH2CH3), 3.19 (q, 2H, J = 6.0 Hz, CH2CH3), 3.82 (d, 1H, J = 4.0 Hz,
40-H), 4.38 (d, 1H, J = 4.5 Hz, 30-H), 4.59 (d, 1H, J = 3.6 Hz, 20-H),
4.67 (d, 2H, J = 4.5 Hz, N–CH2), 5.60 (d, 1H, J = 5.0 Hz, exchangeable
with D2O, OH), 5.77 (d, 1H, J = 4.8 Hz, exchangeable with D2O, OH),
5.88 (d, 1H, J = 5.0 Hz, 10-H), 7.12 (t, 1H, J = 8.0 Hz, aromatic H), 7.38
(d, 1H, J = 7.6 Hz, aromatic H), 7.60 (d, 1H, J = 7.6 Hz, aromatic H),
7.73 (s, 1H, aromatic H), 8.25 (s, 1H, H-2), 8.50 (br s, 1H, exchange-
able with D2O, NH), 8.55 (s, 1H, H-8); 13C NMR (CD3OD) d 15.4,
35.3, 44.5, 54.4, 68.0, 79.1, 80.1, 94.5, 120.3, 125.8, 128.5, 130.5,
135.3, 140.4, 142.7, 151.4, 155.5, 172.3, 174.5; FAB-MS m/z 541
(M++1). Anal. Calcd for C19H21IN6O3S: C, 42.23; H, 3.92; N, 15.55;
S, 5.93. Found: C, 42.51; H, 3.95; N, 15.73; S, 5.95.
3.4.6. 9-(50-Cyclopentylaminocarbonyl-40-thio-b-
N6-methyladenine (5f)
D-ribofuranosyl)-
Compound 5f was prepared using cyclopentylamine: yield 65%;
white solid; ½a 2D5
ꢃ13.8 (c 0.13, MeOH); UV (MeOH) kmax 269 nm
ꢂ
(pH 7); 1H NMR (DMSO-d6) d 1.30 (m, 4H, cyclopentyl-CH2 ꢁ 2),
1.59 (m, 4H, cyclopentyl-CH2 ꢁ 2), 2.95 (d, 3H, J = 4.0 Hz, N–CH3),
3.53 (m, 1H, NCH), 3.87 (d, 1H, J = 4.0 Hz, 40-H), 4.07 (dd, 1H,
J = 4.5, 8.0 Hz, 30-H), 4.54 (dd, 1H, J = 5.0, 8.8 Hz, 20-H), 5.55 (d,
1H, J = 4.0 Hz, exchangeable with D2O, OH), 5.78 (d, 1H, J = 4.8 Hz,
exchangeable with D2O, OH), 5.82 (d, 1H, J = 7.8 Hz, 10-H), 8.25 (s,
3.4.10. 9-(50-Cyclopropylaminocarbonyl-40-thio-b-
N6-(3-iodo-benzyl)adenine (5j)
D-ribofuranosyl)-
Compound 5j was prepared using cyclopropyl amine: yield 62%;
white solid; ½a 2D0
ꢃ35.8 (c 0.15, MeOH); UV (MeOH) kmax 272.0 nm
ꢂ
(pH 7); 1H NMR (DMSO-d6) d 0.48 (br s, 2H, cyclopropyl-CH2), 0.72
(m, 2H, cyclopropyl-CH2), 2.54 (m, 1H, NH), 3.80 (d, 1H, J = 4.3 Hz,

W. J. Choi et al. / Bioorg. Med. Chem. 17 (2009) 8003–8011
8009
40-H), 4.18 (dd, 1H, J = 4.0, 8.5 Hz, 30-H), 4.42 (m, 1H, 20-H), 4.70 (br
s, 2H, N–CH2), 5.63 (d, 1H, J = 5.5 Hz, exchangeable with D2O, OH),
5.83 (d, 1H, J = 5.0 Hz, exchangeable with D2O, OH), 5.90 (d, 1H,
J = 5.4 Hz, 10-H), 7.13 (t, 1H, J = 7.8 Hz, aromatic H), 7.35 (d, 1H,
J = 7.6 Hz, aromatic H), 7.60 (d, 1H, J = 7.8 Hz, aromatic H), 7.73
(s, 1H, aromatic H), 8.27 (br s, 1H, H-2), 8.58 (s, 1H, H-8), 8.59
(br s, 1H, exchangeable with D2O, NH); 13C NMR (DMSO-d6) d
8.4, 10.5, 24.5, 50.5, 64.3, 66.8, 77.0, 80.4, 116.5, 127.4, 133.5,
135.4, 135.9, 140.3, 141.5, 148.5 , 150.3, 152.9, 153.5, 171.4;
FAB-MS m/z 553 (M++1). Anal. Calcd for C20H21IN6O3S: C, 43.49;
H, 3.83; N, 15.21; S, 5.80. Found: C, 43.54; H, 3.92; N, 15.28; S, 5.85.
153.5, 154.4, 172.8; FAB-MS m/z 595 (M++1). Anal. Calcd for
C23H27IN6O3S: C, 46.47; H, 4.58; N, 14.14; S, 5.39. Found: C,
46.55; H, 4.46; N, 14.25; S, 5.50.
3.4.14. 9-[50-(3-Fluoro-benzylaminocarbonyl-40-thio-b-
anosyl)]-N6-(3-iodobenzyl)adenine (5n)
D-ribofur-
Compound 5n was prepared using 3-fluoro-benzylamine: yield
59%; white solid; ½a D20
ꢃ40.1 (c 0.10, MeOH); UV (MeOH) kmax
ꢂ
1
272 nm (pH 7); H NMR (DMSO-d6) d 3.79 (d, 1H, J = 4.0 Hz, 40-
H), 4.28 (m, 3H, 30-H, N–CH2), 4.50 (d, 1H, J = 4.0 Hz, 20-H), 4.62
(d, 2H, J = 4.4 Hz, N–CH2), 5.54 (d, 1H, J = 5.6 Hz, exchangeable with
D2O, OH), 5.67 (d, 1H, J = 4.8 Hz, exchangeable with D2O, OH), 5.78
(d, 1H, J = 5.2 Hz, 10-H), 6.92–7.58 (m, 8H, aromatic H), 8.34 (s, 1H,
H-2), 8.53 (s, 1H, H-8), 8.91 (br s, 1H, exchangeable with D2O, NH),
9.03 (br s, 1H, exchangeable with D2O, NH); 13C NMR (CD3OD) d
50.3, 52.4, 54.3, 60.4, 77.4, 78.5, 101.3, 114.3, 115.4, 116.8, 125.7,
125.9, 128.4, 130.5, 135.0, 140.3, 142.1, 145.8, 150.2, 155.31,
158.2, 160.5, 164.8, 173.5; FAB-MS m/z 621 (M++1). Anal. Calcd
for C24H22FIN6O3S: C, 46.46; H, 3.57; N, 13.55; S, 5.17. Found: C,
46.55; H, 3.46; N, 13.65; S, 5.26.
3.4.11. 9-(50-Cyclopropylmethylaminocarbonyl-40-thio-b-
furanosyl)-N6-(3-iodobenzyl)adenine (5k)
D-ribo-
Compound 5k was prepared using cyclopropylmethyl ami-
neꢀHCl: yield 61%; white solid; ½a D20
ꢃ14.8 (c 0.15, MeOH); UV
ꢂ
(MeOH) kmax 274.0 nm (pH 7); 1H NMR (DMSO-d6) d 0.18 (m, 2H,
cyclopropyl-CH2), 0.23 (m, 2H, cyclopropyl-CH2), 0.75 (m, 1H,
cyclopropyl-CH), 2.54 (m, 1H, NH), 2.87 (t, 2H, J = 3.8 Hz, N–CH2),
3.67 (d, 1H, J = 4.2 Hz, 40-H), 4.19 (dd, 1H, J = 4.0, 8.7 Hz, 30-H),
4.42 (m, 1H, 20-H), 4.47 (br s, 2H, N–CH2-cyclopropyl), 5.41 (d,
1H, J = 5.0 Hz, exchangeable with D2O, OH), 5.59 (d, 1H, J = 4.8 Hz,
exchangeable with D2O, OH), 5.70 (d, 1H, J = 5.3 Hz, 10-H), 6.92 (t,
1H, J = 7.6 Hz, aromatic H), 7.18 (d, 1H, J = 7.6 Hz, aromatic H),
7.40 (d, 1H, J = 7.8 Hz, aromatic H), 7.53 (s, 1H, aromatic H), 8.05
(br s, 1H, H-2), 8.33 (s, 1H, H-8), 8.43 (br s, 1H, exchangeable with
D2O, NH); 13C NMR (DMSO-d6) d 2.3, 3.2, 13.4, 23.8, 54.3, 63.5, 67.0,
77.4, 81.0, 116.4, 126.3, 132.1, 133.4, 135.2, 139.8, 140.2, 147.5 ,
150.1, 151.9, 153.4, 171.8; FAB-MS m/z 567 (M++1). Anal. Calcd
for C21H23IN6O3S: C, 44.53; H, 4.09; N, 14.84; S, 5.66. Found: C,
44.60; H, 4.12; N, 14.95; S, 5.62.
3.4.15. 9-[50-(3-Chloro-benzylaminocarbonyl-40-thio-b-
anosyl)]-N6-(3-iodobenzyl)adenine (5o)
D-ribofur-
Compound 5o was prepared using 3-chloro-benzylamine: yield
68%; white solid; ½a D20
ꢃ25.4 (c 0.13, MeOH); UV (MeOH) kmax
ꢂ
1
273 nm (pH 7); H NMR (DMSO-d6) d 3.78 (d, 1H, J = 3.8 Hz, 40-
H), 4.26 (m, 3H, 30-H, N–CH2), 4.49 (m, 3H, N–CH2), 5.52 (d, 1H,
J = 5.0 Hz, exchangeable with D2O, OH), 5.67 (d, 1H, J = 4.8 Hz,
exchangeable with D2O, OH), 5.77 (d, 1H, J = 5.2 Hz, 10-H), 6.94–
7.58 (m, 8H, aromatic H), 8.03 (s, 1H, H-2), 8.37 (s, 1H, H-8), 8.38
(br s, 1H, exchangeable with D2O, NH), 9.02 (br s, 1H, exchangeable
with D2O, NH); 13C NMR (CD3OD) d 51.4, 52.5, 54.0, 61.3, 78.1, 79.8,
102.3, 114.8, 115.6, 117.2, 125.9, 128.0, 136.3, 138.4, 140.0, 141.2,
142.0, 148.3, 149.5, 150.2, 153.4, 157.2, 158.4, 174.0; FAB-MS m/z
637 (M++1). Anal. Calcd for C24H22ClIN6O3S: C, 45.26; H, 3.48; N,
13.20; S, 5.03. Found: C, 45.46; H, 3.46; N, 13.25; S, 5.26.
3.4.12. 9-(50-Cyclobutylaminocarbonyl-40-thio-b-
N6-(3-iodobenzyl)adenine (5l)
D-ribofuranosyl)-
Compound 5l was prepared using cyclobutyl amine: yield 53%;
white solid; ½a 2D0
ꢃ15.3 (c 0.10, MeOH); UV (MeOH) kmax 270 nm
ꢂ
(pH 7); 1H NMR (DMSO-d6) d 1.71 (m, 2H, cyclobutyl-CH2), 1.96
(m, 2H, cyclobutyl-CH2), 2.25 (m, 2H, cyclobutyl-CH2), 3.84 (d,
1H, J = 4.0 Hz, 40-H), 4.30 (m, 1H, NCH), 4.41 (dd, 1H, J = 4.5,
8.7 Hz, 30-H), 4.61 (m, 1H, 20-H), 4.70 (br s, 2H, N–CH2), 5.63 (d,
1H, J = 5.5 Hz, exchangeable with D2O, OH), 5.83 (d, 1H, J = 5.0 Hz,
exchangeable with D2O, OH), 5.90 (d, 1H, J = 5.4 Hz, 10-H), 7.15 (t,
1H, J = 8.0 Hz, aromatic H), 7.41 (d, 1H, J = 7.6 Hz, aromatic H),
7.62 (d, 1H, J = 7.8 Hz, aromatic H), 7.76 (s, 1H, aromatic H), 8.28
(br s, 1H, H-2), 8.57 (s, 1H, H-8), 8.72 (br s, 1H, exchangeable with
D2O, NH); 13C NMR (DMSO-d6) d 20.4, 35.3, 37.2, 50.5, 54.8, 64.2,
66.5, 78.0, 79.5, 116.4, 126.5, 132.7, 135.3, 135.8, 141.7, 142.3,
148.4, 151.3, 153.0, 154.5, 172.0; FAB-MS m/z 567 (M++1). Anal.
Calcd for C21H23IN6O3S: C, 44.53; H, 4.09; N, 14.84; S, 5.66. Found:
C, 44.55; H, 4.12; N, 14.96; S, 5.70.
3.4.16. N6-(3-Iodo-benzyl)-9-[50-(2-methyl-benzylaminocarbonyl-
40-thio-b-
D-ribofuranosyl)]adenine (5p)
Compound 5p was prepared using 2-methyl-benzylamine:
yield 60%; white solid; ½a D20
ꢃ43.0 (c 0.10, MeOH); UV (MeOH) kmax
ꢂ
274 nm (pH 7); 1H NMR (DMSO-d6) d 2.32 (s, 3H, CH3), 3.98 (d, 1H,
J = 2.7 Hz, 40-H), 4.40 (m, 3H, 30-H, N–CH2), 4.69 (m, 3H, 20-H, N–
CH2), 5.68 (d, 1H, J = 5.0 Hz, exchangeable with D2O, OH), 5.85 (d,
1H, J = 4.8 Hz, exchangeable with D2O, OH), 5.94 (d, 1H, J = 5.0 Hz,
10-H), 7.13–7.76 (m, 8H, aromatic H), 8.11 (s, 1H, H-2), 8.54 (s,
1H, H-8), 8.96 (br s, 1H, exchangeable with D2O, NH); 13C NMR
(CD3OD) d 24.8, 49.8, 50.3, 52.8, 56.3, 68.4, 78.0, 80.3, 98.6, 102.4,
115.8, 120.3, 125.6, 135.4, 137.6, 139.8, 140.4, 142.5, 146.4,
148.1, 151.3, 154.5, 156.7, 158.4, 173.8; FAB-MS m/z 617 (M++1).
Anal. Calcd for C25H25IN6O3S: C, 48.71; H, 4.09; N, 13.63; S, 5.20.
Found: C, 48.88; H, 4.14; N, 13.82; S, 5.26.
3.4.13. 9-(50-Cyclohexylaminocarbonyl-40-thio-b-
N6-(3-iodobenzyl)adenine (5m)
D-ribofuranosyl)-
Compound 5m was prepared using cyclohexyl amine: yield
3.4.17. N6-(3-Iodo-benzyl)-9-[50-(3-methyl-benzylaminocarbonyl-
68%; white solid; ½a D20
ꢂ
ꢃ25.4 (c 0.13, MeOH); UV (MeOH) kmax
40-thio-b-
D-ribofuranosyl)]adenine (5q)
272 nm (pH 7); 1H NMR (DMSO-d6) d 1.41–1.82 (m, 10H, cyclo-
hexyl-CH2), 3.65 (m, 1H, cyclohexyl-CH), 3.83 (d, 1H, J = 4.5 Hz,
40-H), 4.45 (dd, 1H, J = 4.4, 9.0 Hz, 30-H), 4.75 (m, 1H, 20-H), 4.82
(br s, 2H, N–CH2), 5.65 (d, 1H, J = 5.5 Hz, exchangeable with D2O,
OH), 5.85 (d, 1H, J = 5.0 Hz, exchangeable with D2O, OH), 5.95 (d,
1H, J = 5.4 Hz, 10-H), 7.25 (t, 1H, J = 7.5 Hz, aromatic H), 7.43 (d,
1H, J = 8.0 Hz, aromatic H), 7.65 (d, 1H, J = 7.8 Hz, aromatic H),
7.79 (s, 1H, aromatic H), 8.25 (br s, 1H, H-2), 8.54 (s, 1H, H-8),
8.56 (br s, 1H, exchangeable with D2O, NH); 13C NMR (DMSO-d6)
d 20.5, 22.4, 30.5, 35.4, 36.8, 46.3, 55.6, 64.4, 66.9, 77.5, 79.4,
117.5, 128.4, 133.5, 134.0, 135.6, 141.6, 142.1, 148.5, 152.1,
Compound 5q was prepared using 3-methyl-benzylamine:
yield 58%; white solid; ½a D20
ꢃ33.5 (c 0.13, MeOH); UV (MeOH) kmax
ꢂ
274 nm (pH 7); 1H NMR (DMSO-d6) d 2.31 (s, 3H, CH3), 3.96 (d, 1H,
J = 2.0 Hz, 40-H), 4.40 (d, 2H, J = 8.0 Hz, N–CH2), 4.45 (dd, 1H, J = 5.2,
7.8 Hz, 30-H), 4.68 (m, 3H, 20-H, N–CH2), 5.69 (d, 1H, J = 5.0 Hz,
exchangeable with D2O, OH), 5.84 (d, 1H, J = 4.8 Hz, exchangeable
with D2O, OH), 5.94 (d, 1H, J = 5.0 Hz, 10-H), 7.09–7.76 (m, 8H, aro-
matic H), 8.17 (s, 1H, H-2), 8.53 (s, 1H, H-8), 8.54 (br s, 1H,
exchangeable with D2O, NH), 8.96 (br s, 1H, exchangeable with
D2O, NH); 13C NMR (CD3OD) d 23.5, 50.0, 50.4, 52.8, 56.4, 68.4,
78.1, 80.3, 98.6, 102.4, 115.9, 120.3, 125.6, 135.4, 136.5, 140.0,

8010
W. J. Choi et al. / Bioorg. Med. Chem. 17 (2009) 8003–8011
140.5, 142.5, 146.5, 148.2, 151.3, 154.6, 156.7, 158.5, 174.0; FAB-
MS m/z 617 (M++1). Anal. Calcd for C25H25IN6O3S: C, 48.71; H,
4.09; N, 13.63; S, 5.20. Found: C, 48.85; H, 4.13; N, 13.62; S, 5.15.
55.3, 60.4, 73.8, 89.1, 98.4, 121.2, 122.4, 122.5, 124.1, 124.8,
126.3, 127.0, 127.8, 128.1, 129.2, 132.4, 133.5, 135.4, 136.0,
144.8, 145.5, 147.8, 152.0, 154.4, 156.8, 174.4; FAB-MS m/z 653
(M++1). Anal. Calcd for C28H25IN6O3S: C, 51.54; H, 3.86; N, 12.88;
S, 4.91. Found: C, 51.68; H, 3.92; N, 12.92; S, 4.90.
3.4.18. N6-(3-Iodo-benzyl)-9-[50-(4-methyl-benzylaminocarbonyl-
40-thio-b-
D-ribofuranosyl)]adenine (5r)
Compound 5r was prepared using 4-methyl-benzylamine: yield
3.4.22. N6-(3-Iodo-benzyl)-9-[50-(2-phenetylaminocarbonyl-40-
thio-b-D-ribofuranosyl)]adenine (5v)
60%; white solid; ½a D20
ꢂ
ꢃ38.1 (c 0.15, MeOH); UV (MeOH) kmax
273 nm (pH 7); 1H NMR (DMSO-d6) d 2.31 (s, 3H, CH3), 3.95 (d,
1H, J = 2.5 Hz, 40-H), 4.39 (d, 2H, J = 8.0 Hz, N–CH2), 4.44 (br s, 1H,
30-H), 4.68 (br s, 3H, 20-H, N–CH2), 5.69 (br s, 1H, exchangeable
with D2O, OH), 5.82 (br s, 1H, exchangeable with D2O, OH), 5.95
(d, 1H, J = 4.8 Hz, 10-H), 7.13–7.76 (m, 8H, aromatic H), 8.16 (s,
1H, H-2), 8.53 (s, 1H, H-8), 8.54 (br s, 1H, exchangeable with
D2O, NH), 9.13 (br s, 1H, exchangeable with D2O, NH); 13C NMR
(CD3OD) d 20.9, 49.8, 50.5, 53.4, 56.5, 67.9, 78.4, 80.5, 98.9, 102.7,
116.3, 120.4, 125.6, 135.5, 136.7, 140.5, 140.9, 142.5, 146.4,
148.2, 151.4, 154.6, 156.8, 158.5, 173.9; FAB-MS m/z 617 (M++1).
Anal. Calcd for C25H25IN6O3S: C, 48.71; H, 4.09; N, 13.63; S, 5.20.
Found: C, 48.79; H, 4.15; N, 13.55; S, 5.18.
Compound 5v was prepared using 2-phenylethylamine: yield
59%; white solid; ½a D20
ꢃ45.0 (c 0.15, MeOH); UV (MeOH) kmax
ꢂ
270 nm (pH 7); 1H NMR (DMSO-d6) d 2.65 (t, 2H, J = 2.5 Hz,
NCH2CH2), 3.54 (m, 2H, NCH2CH2), 3.71 (d, 1H, J = 4.0 Hz, 40-H),
4.23 (br s, 1H, 30-H), 4.48 (br s, 1H, 20-H), 4.55 (d, 2H, J = 8.0 Hz,
N–CH2), 5.51 (br s, 1H, exchangeable with D2O, OH), 5.65 (br s,
1H, exchangeable with D2O, OH), 5.77 (d, 1H, J = 5.2 Hz, 10-H),
6.98–7.61 (m, 9H, aromatic H), 8.09 (s, 1H, H-2), 8.38 (s, 1H, H-
8), 8.39 (br s, 1H, exchangeable with D2O, NH), 8.57 (br s, 1H,
exchangeable with D2O, NH); 13C NMR (CD3OD) d 37.3, 44.5,
45.3, 56.0, 60.3, 74.2, 79.8, 97.3, 123.1, 123.4, 124.5, 125.3, 126.4,
126.8, 127.1, 128.4, 129.4, 136.2, 137.1, 144.3, 145.2, 147.1,
147.8, 154.2, 174.5; FAB-MS m/z 617 (M++1). Anal. Calcd for
C25H25IN6O3S: C, 48.71; H, 4.09; N, 13.63; S, 5.20. Found: C,
48.79; H, 4.15; N, 13.55; S, 5.18.
3.4.19. N6-(3-Iodo-benzyl)-9-[50-(2-methoxy-benzylaminocarbon-
yl-40-thio-b-
D-ribofuranosyl)]adenine (5s)
Compound 5s was prepared using 2-methoxy-benzylamine:
yield 72%; white solid; ½a D20
ꢃ30.2 (c 0.10, MeOH); UV (MeOH) kmax
ꢂ
3.4.23. 9-[50-(3,3-Diphenylpropylaminocarbonyl-40-thio-b-
ribofuranosyl)]-N6-(3-iodobenzyl)adenine (5w)
D-
270 nm (pH 7); 1H NMR (DMSO-d6) d 3.83 (s, 3H, OCH3), 3.98 (d,
1H, J = 2.5 Hz, 40-H), 4.38 (m, 3H, 30-H, N–CH2), 4.69 (m, 3H, 20-H,
N–CH2), 5.69 (d, 1H, J = 5.5 Hz, exchangeable with D2O, OH), 5.82
(d, 1H, J = 4.8 Hz, exchangeable with D2O, OH), 5.94 (d, 1H,
J = 5.0 Hz, 10-H), 6.94–7.61 (m, 8H, aromatic H), 8.15 (s, 1H, H-2),
8.53 (br s, 1H, exchangeable with D2O, NH), 8.54 (s, 1H, H-8),
8.97 (br s, 1H, exchangeable with D2O, NH); 13C NMR (CD3OD) d
49.8, 50.4, 52.8, 56.3, 57.8, 68.0, 78.4, 80.9, 98.5, 102.8, 115.8,
120.5, 125.6, 135.8, 137.6, 139.8, 140.5, 142.7, 146.4, 148.1,
151.8, 153.5, 156.9, 158.3, 173.9; FAB-MS m/z 633 (M++1). Anal.
Calcd for C25H25IN6O4S: C, 48.48; H, 3.98; N, 13.29; S, 5.07. Found:
C, 48.65; H, 4.04; N, 13.42; S, 5.01.
Compound 5w was prepared using 3,3-diphenylpropylamine:
yield 72%; white solid; ½a D20
ꢃ25.6 (c 0.32, MeOH); UV (MeOH) kmax
ꢂ
274 nm (pH 7); 1H NMR (DMSO-d6) d 2.27 (m, 2H, NCH2CH2CH),
3.10 (m, 2H, NCH2CH2CH), 3.87 (d, 1H, J = 4.0 Hz, 40-H), 4.07 (t,
1H, J = 8.0 Hz, NCH2CH2CH), 4.41 (dd, 1H, J = 3.6, 7.4 Hz, 30-H),
4.64 (m, 1H, 20-H), 4.69 (d, 2H, J = 5.7 Hz, N–CH2), 5.64 (d, 1H,
J = 5.6 Hz, exchangeable with D2O, OH), 5.83 (d, 1H, J = 5.6 Hz,
exchangeable with D2O, OH), 5.93 (d, 2H, J = 4.2 Hz, 10-H), 7.13–
7.76 (m, 14H, aromatic H), 8.20 (s, 1H, H-2), 8.54 (s, 1H, H-8),
8.55 (br s, 1H, exchangeable with D2O, NH), 8.62 (br d, 1H,
J = 6.1 Hz, exchangeable with D2O, NH); 13C NMR (CD3OD) d 34.5,
35.3, 40.6, 45.5, 60.1, 73.4, 79.1, 80.4, 97.1, 112.3, 120.5, 126.0,
128.4, 129.3, 129.5, 129.7, 129.9, 132.7, 135.3, 141.5, 143.0,
144.3, 147.8, 152.4, 155.7, 174.8; FAB-MS m/z 707 (M++1). Anal.
Calcd for C32H31IN6O3S: C, 54.39; H, 4.42; N, 11.89; S, 4.54. Found:
C, 54.48; H, 4.45; N, 11.75; S, 4.64.
3.4.20. 9-[50-(2-Ethoxy-benzylaminocarbonyl-40-thio-b-
anosyl)]-N6-(3-iodobenzyl)adenine (5t)
D-ribofur-
Compound 5t was prepared using 2-ethoxy-benzylamine: yield
63%; white solid; ½a D20
ꢃ35.8 (c 0.10, MeOH); UV (MeOH) kmax
ꢂ
270 nm (pH 7); 1H NMR (DMSO-d6) d 1.36 (t, 3H, J = 4.2 Hz,
OCH2CH3), 4.09 (m, 2H, OCH2CH3), 3.98 (d, 1H, J = 2.5 Hz, 40-H),
4.38 (m, 3H, 30-H, N–CH2), 4.70 (m, 3H, 20-H, N–CH2), 5.69 (d, 1H,
J = 5.5 Hz, exchangeable with D2O, OH), 5.83 (d, 1H, J = 4.8 Hz,
exchangeable with D2O, OH), 5.95 (d, 1H, J = 4.8 Hz, 10-H), 6.93–
7.76 (m, 8H, aromatic H), 8.14 (s, 1H, H-2), 8.53 (br s, 1H,
exchangeable with D2O, NH), 8.54 (s, 1H, H-8), 8.93 (br s, 1H,
exchangeable with D2O, NH); 13C NMR (CD3OD) d 23.8, 48.2,
51.3, 52.8, 57.8, 65.2, 67.3, 78.4, 81.0, 98.6, 103.4, 116.4, 120.1,
124.5, 135.7, 137.8, 139.8, 141.3, 142.9, 146.5, 148.3, 152.1,
153.6, 155.4, 158.4, 170.1; FAB-MS m/z 647 (M++1). Anal. Calcd
for C26H27IN6O4S: C, 48.30; H, 4.21; N, 13.00; S, 4.96. Found: C,
48.35; H, 4.24; N, 13.13; S, 5.04.
Acknowledgments
This work was supported by the grant from the World Class
University (WCU) Project from Ministry of Education and Science,
Korea (R31-2008-000-10010-0) and Seoul R; BD Program, Korea
(10541). K.A.J. and Z.G. acknowledge support from the NIDDK
Intramural Research Program of the National Institutes of Health.
References and notes
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3.4.21. N6-(3-Iodo-benzyl)-9-[50-(1-naphthylmethylaminocarbon-
yl-40-thio-b-
D-ribofuranosyl)]adenine (5u)
Compound 5u was prepared using 1-naphthyl-methylamine:
yield 57%; white solid; ½a D20
ꢃ13.5 (c 0.15, MeOH); UV (MeOH) kmax
ꢂ
1
273 nm (pH 7); H NMR (DMSO-d6) d 3.97 (d, 1H, J = 2.5 Hz, 40-H),
4.47 (d, 2H, J = 8.4 Hz, N–CH2), 4.68 (br s, 1H, 30-H), 4.92 (br s, 3H,
20-H, N–CH2), 5.66 (br s, 1H, exchangeable with D2O, OH), 5.82 (br
s, 1H, exchangeable with D2O, OH), 5.93 (d, 1H, J = 4.8 Hz, 10-H),
7.10–7.98 (m, 11H, aromatic H), 8.10 (s, 1H, H-2), 8.53 (s, 1H,
H-8), 8.54 (br s, 1H, exchangeable with D2O, NH), 9.09 (br s, 1H,
exchangeable with D2O, NH); 13C NMR (CD3OD) d 45.3, 46.5,

W. J. Choi et al. / Bioorg. Med. Chem. 17 (2009) 8003–8011
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