Syntheses, molecular structures, and antiviral activities of 1- and 2-(2′-deoxy-d-ribofuranosyl)cyclohepta[d][1,2,3]triazol-6(1H)-ones and 1-(2′-deoxy-d-ribofuranosyl)cyclohepta[b]pyrrol-8(1H)-one

Article abstract of DOI:10.1016/j.tet.2012.04.109

The synthesis of a novel class of 2′-deoxyribonucleosides possessing tropone-fused nitrogen heterocycles as nucleobases was developed. The reaction of alkali metal salts of 1H-cyclohepta[d][1,2,3]triazol-6-one with 2-deoxy-3,5-di-O-(p-toluoyl)-α-d-ribofuranosyl chloride (α-chlorosugar) afforded an anomeric mixture of N1- and N2-coupled glycosylation products. Good stereospecificity in relation to the amount of the β-anomer was achieved in the less polar solvent DME. The reactions of the sodium salt of 1H-cyclohepta[b]pyrrol-8-one and its 3-methyl derivative with an α-chlorosugar in DME gave the β-anomer of the N1-coupled glycosylation products. The glycosylation products were treated with NaOMe in MeOH to produce the desired 2′-deoxyribonucleosides. X-ray structural analyses of the three nucleosides prepared confirmed their anomeric configuration and revealed that their sugars were puckered. The β-anomers of the nucleosides had weak antiviral activities for herpes simplex virus type 1 and herpes simplex virus type 2 in comparison with those of acyclovir (ACV). These nucleosides showed no cytotoxicity on a lung (A549) and two colon (HT-29 and HCT-116) cancer cell lines.

Full text of DOI:10.1016/j.tet.2012.04.109

Tetrahedron 68 (2012) 5368e5374
Contents lists available at SciVerse ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Syntheses, molecular structures, and antiviral activities of 1- and
2-(20-deoxy-
-ribofuranosyl)cyclohepta[d][1,2,3]triazol-6(1H)-ones
D
and 1-(20-deoxy-
-ribofuranosyl)cyclohepta[b]pyrrol-8(1H)-one
D
,
a
b
c
a
Tomoo Nakazawa a , Takeshi Ohmae , Masahiro Fujimuro , Masahiko Ito , Tohru Nishinaga ,
*
,
Masahiko Iyoda a
*
a Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
b Department of Cell Biology, Kyoto Pharmaceutical University, Misasagi-Shichonocho 1, Yamashinaku, Kyoto 607-8412, Japan
c Department of Microbiology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Shimokato, Chuoh, Yamanashi 409-3898, Japan
a r t i c l e i n f o
a b s t r a c t
The synthesis of a novel class of 20-deoxyribonucleosides possessing tropone-fused nitrogen heterocycles
as nucleobases was developed. The reaction of alkali metal salts of 1H-cyclohepta[d][1,2,3]triazol-6-one
Article history:
Received 8 March 2012
Received in revised form 26 April 2012
Accepted 28 April 2012
Available online 3 May 2012
with 2-deoxy-3,5-di-O-(p-toluoyl)-
mixture of N1- and N2-coupled glycosylation products. Good stereospecificity in relation to the amount
of the -anomer was achieved in the less polar solvent DME. The reactions of the sodium salt of 1H-
cyclohepta[b]pyrrol-8-one and its 3-methyl derivative with an -chlorosugar in DME gave the -anomer
a-D-ribofuranosyl chloride (a-chlorosugar) afforded an anomeric
b
a
b
Keywords:
of the N1-coupled glycosylation products. The glycosylation products were treated with NaOMe in MeOH
to produce the desired 20-deoxyribonucleosides. X-ray structural analyses of the three nucleosides
prepared confirmed their anomeric configuration and revealed that their sugars were puckered. The b-
anomers of the nucleosides had weak antiviral activities for herpes simplex virus type 1 and herpes
simplex virus type 2 in comparison with those of acyclovir (ACV). These nucleosides showed no cyto-
toxicity on a lung (A549) and two colon (HT-29 and HCT-116) cancer cell lines.
Ó 2012 Elsevier Ltd. All rights reserved.
20-Deoxyribofuranosides
Cyclohepta[d][1,2,3]triazol-6(1H)-ones
Cyclohepta[b]pyrrol-8(1H)-ones
Glycosylation
X-ray structures
1. Introduction
was employed because of its importance and usefulness in the field
of nucleoside chemistry9 and because of the facile access to 20-
A number of fused seven-membered aromatics, such as azaa-
zulenes1 and troponoids condensed with a heterocyclic ring,2 have
been synthesized, and some of them exhibit biological activitie-
deoxyribonucleosides by using a simple glycosylation reaction.10
We report herein the glycosylation of 5e7 with 2-deoxy-3,5-di-O-
s.1a,d,e,2b The nucleoside coformycin, which has
a 3,6,7,8-
tetrahydro-1,3,4,6-tetraazaazulene ring, is a potent inhibitor of
adenosine deaminase.3 Nucleosides with a fused seven-membered
azaaromatic system are interesting building blocks for a novel class
of nucleoside analogs. Synthesis of
b-ribo- and b-arabinonucleo-
sides (1e4) with 1-azaazulen-2(1H)-one, 1,3-diazaazulen-2(1H)-
one and its thione, together with the a-anomers of 3 and 4 have
been reported (Fig. 1).4 The biological activity of triazoles5 and
pyrroles6 and the biochemical and pharmacodynamic interest in
troponoid-fused triazoles7 and pyrroles8 prompted us to synthesize
nucleoside analogs with 1H-cyclohepta[d][1,2,3]triazol-6-one 5,
1H-cyclohepta[b]pyrrol-8-one 6, and its methyl derivative 7 as
nucleobases. For the sugar moiety of the analog, 2-deoxy-D-ribose
Fig. 1. Molecular structures of b-ribo- and b-arabinonucleosides with 1-aza- and 1,3-
* Corresponding authors. Tel.: þ81 42 677 2731; fax: þ81 42 677 2525; e-mail
diazaazulen-2(1H)-one (thione) 1e4 together with tropone-fused nitrogen heterocy-
cles 5e7.
addresses: tomoon@yamanashi.ac.jp (T. Nakazawa), iyoda@tmu.ac.jp (M. Iyoda).
0040-4020/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2012.04.109

T. Nakazawa et al. / Tetrahedron 68 (2012) 5368e5374
5369
(p-toluoyl)-
a
-
D
-ribofuranosyl chloride (
a
-chlorosugar) 8,10a depro-
shown in Table 2. Anomers 9 and 11 are coupling products of 5 at
the N2 position, i.e., 2-( -ribofuranosyl)cyclohepta[d][1,2,3]triazol-
8(1H)-one, because of equivalent H4 and H8 and H5 and H7 pro-
tons, whereas anomers 10 and 12 are coupling products of 5 at the
tection of the glycosylation products, their molecular structures
based on X-ray structural analyses, and their antiviral and anti-
cellular activities.
D
N1 position, i.e., 1-(D-ribofuranosyl)cyclohepta[d][1,2,3]triazol-
8(1H)-one, on the basis of the two pairs of AX type protons (H4 and
H5 and H7 and H8). (3) Anomeric configurations of 9, 11, and 12
were determined on the basis of the coupling patterns of the peaks
2. Results and discussions
1H-Cyclohepta[d][1,2,3]triazol-6-one 5, 1H-cyclohepta[b]-pyr-
rol-8-one 6, and its methyl derivative 7 were prepared following
reported methods.11,12 Alkali metal salts of 5 were easily prepared
by treating it with an equimolar amount of LiOH, NaOH, NaHCO3, or
KOH in water, followed by evaporation to dryness.
for the H10 proton of the
b
-anomer of 10, as shown in Table 2.
Anomer 9, of which the H10 signal appeared as a triplet-like signal,
like 10, was assigned to have a -D configuration, whereas anomers
11 and 12, of which the H10 signal appeared as doublets of doublets,
b
were assigned to have a-D configurations. These assignments agree
Metal salts of 5 were reacted with a-chlorosugar 8 in acetone,
with those of related nucleosides.14
DMF, or DME at room temperature, affording four glycosylation
products 9e12, as shown in Scheme 1 and Table 1. These four
products were separated by using column chromatography and/or
preparative thin layer chromatography. The structure of 10, de-
termined from X-ray analysis, which is described below, is a gly-
As shown in Table 1, the glycosylation products from 1H-cyclo-
hepta[d][1,2,3]triazol-6-one 5 were obtained in relatively good
yields. From the viewpoint of the anomeric stereoselectivity,
b-
anomers 9 and 10 and -anomers 11 and 12 were obtained in
a
comparative yields in moderately polar solvents, such as acetone
and dimethylformamide (DMF) (entries 1e3). The relative ratios of
cosylation product of the b-anomer formed through N1-coupling of
5 and allowed us to confirm the assignment of the 1H NMR spec-
trum of 10. Anomeric structures of 9, 11, and 12 were determined
from their 1H NMR spectra as follows. (1) 20-Deoxyribose moieties
of 9e12 were assigned on the basis of the characteristic H10, H20,
H30, H40, and H50 peaks of the sugar groups and those of the pro-
tecting groups. (2) The structures of cyclohepta[d]triazol moieties
were determined on the basis of the 1H NMR data of 9e12, as
the yields of the
the metal counter cation of the salt of 5 (entries 2 and 3). Good
stereoselectivities were achieved in less polar DME (entries 4 and
5). The relative yield of -anomer 9 to -isomer 11 was comparable
with that of -anomer 10 to -isomer 12 under each reaction
condition (entries 1e5). The above results were explained in terms
of the easy anomerization of
-chlorosugar 8 in polar solvents.10d,15
b-anomers to those of the a-anomers depended on
b
-
b
a
b
a
a
Concerning the regioselectivity of the glycosylation reaction, the
ratios of the yield of N2-coupling products 9 and 11 to those of N1-
coupling products 10 and 12 were dependent on the metal cations
(entries 2 and 3) and solvent polarity (entries 1e4), as shown in
Table 1. The ratios were larger in less polar solvents, such as DME. A
similar substitution reaction involving 5 and O-(2,4-dinitropheny)
hydroxylamine, giving products substituted with N2- and N1-
amino groups, has been reported.16 In order to deprotect the
30,50-di-O-(p-toluoyl) glycosylation products, 9‒12 were reacted
with NaOCH3 in CH3OH to afford 13‒16 in moderate to good yields
with liberation of methyl p-toluate. The structures of 13‒16 were
confirmed by using 1H NMR spectroscopy.
Glycosylation product 10 was recrystallized from benzene/ether
to give single crystals suitable for X-ray analysis. The X-ray struc-
ture of 10, which is in a b
-D configuration, is shown in Fig. 2.13
In order to synthesize 20-deoxyribonucleosides with cyclo-
heptapyrrolone as a nucleobase, sodium salts of 1H-cyclohepta[b]
pyrrol-8-one 6 and its methyl derivative 7 were prepared by
reacting 6 and 7 with equimolar amounts of NaOC2H5 in anhydrous
ethanol, followed by evaporation to dryness. The reactions of 2-
deoxy-3,5-di-O-(p-toluoyl)-
a
-
D
-ribofuranosyl chloride
8
with
Naþ$6ꢀ and Naþ$7ꢀ afforded glycosylation products 17 and 18 in
65% and 70% yields, respectively. In a similar manner to the con-
version of 9 and 10 to 13 and 14, 17 and 18 were treated with
NaOCH3 in CH3OH to afford 19 and 20 in 90% and 67% yields, re-
spectively (Scheme 2).
X-ray quality single crystals of 20-deoxyribonucleosides of 18
and 19 were obtained by recrystallization from benzene/hexane
and methanol/dichloromethane, respectively. X-ray structures of 18
and 19, shown in Figs. 3 and 4, show that they are glycosylation
products formed through N1-coupling of 6 and 7 and that they have
b-D configurations. In addition, 17 and 20 were confirmed to be b-
anomers. The b-configuration of 17 was assigned on the basis of the
H10 signal in the 1H NMR spectrum, which was a triplet, as shown in
Table 2. Moreover, the anomeric configuration of 18 was main-
tained during deprotection under mild basic conditions.
The X-ray structures of 10, 18, and 19 exhibit important con-
formational features. Considering the similarities of tropone-fused
nitrogen heterocycles 5 and 6 to purine bases, the syn- and anti-
Scheme 1. Synthesis of 20-deoxyribonucleosides 13e16 by reacting the alkali metal
salt of 1H-cyclohepta[d][1,2,3]triazol-6-one 5 with 8, followed by deprotection.

5370
T. Nakazawa et al. / Tetrahedron 68 (2012) 5368e5374
Table 1
Yields of the glycosylation products 9e12 under various conditions
Entry
Metal cation of 5
Solventa
Total yield (%) of 9 and 11 (ratio of 9:11)
Total yield (%) of 10 and 12 (ratio of 10:12)
Total yield (%) of 9, 10, 11, and 12
1
2
3
4
5
Liþ
Acetone
DMF
DMF
DME
DME
41.3 (39:61)
49.5 (45:55)
34.9 (72:28)
60.0 (98:2)
61.7 (99:1)
34.5 (34:66)
38.4 (45:55)
45.9 (69:31)
25.5 (95:5)
25.1 (96:4)
75.8
87.9
80.8
85.5
86.8
Liþ
Naþ
Naþ
Kþ
a
DMF (dimethylformamide) and DME (dimethoxyethane).
Table 2
Selected 1H chemical shifts (
products 9e12, 17, and 18
d, ppm) and coupling constants (Hz) of the glycosylation
Compound H10 of sugar moietya,b H4 and H8 of 9, 10, H5 and H7 of 9, 10,
11, and 12a,b 11, and 12a,b
9
10
6.60 (t, Jz6.0)
6.57 (t, Jz6.0)
7.50 (d, 2H, J¼12.2) 6.82 (d, 2H, J¼12.2)
7.66 (d, J¼12.2)
7.75 (d, J¼11.9)
6.89 (dd, J¼12.2, 2.1)
6.86 (dd, J¼11.9, 2.1)
11
12
6.59 (dd, J¼6.9, 1.7)
6.60 (dd, J¼7.3, 1.8)
7.56 (d, 2H, J¼11.3) 6.85 (d, 2H, J¼11.3)
7.82 (d, J¼12.2)
7.85 (d, J¼12.2)
6.93 (dd, J¼12.2, 2.1)
6.97 (dd, J¼12.2, 2.1)
17
18
7.61 (br. t, Jz6.6)
7.65 (br. t, Jz6.6)
a
Solvent: CDCl3.
b
1H NMR chemical shift
d/ppm (coupling constant/Hz).
conformations were assigned in relation to the arrangement about
the glycosidic C10eN1 bond and depend on whether the tropone
nucleus lies above the plane of the sugar ring or points away from
it. The glycosidic torsion angle (c
) (O10eC10eN1eC9) was de-
Scheme 2. Reactions of the sodium salts of 1H-cyclohepta[b]pyrrol-8-one 6 and its
methyl derivative 7 with 2-deoxy-3,5-di-O-(p-toluoyl)- -D-ribofuranosyl chloride 8,
affording glycosylation products 17 and 18, respectively, and deprotection of the gly-
termined to be 54.1(6)ꢁ for 10 (syn-conformation), 161.7(3)ꢁ for 18
(anti-conformation), and ꢀ121.3(2)ꢁ for 19 (anti-conformation). X-
ray structures of anti-conformers 18 and 19 show that the H10
protons are close to the tropone oxygen O8 (interatomic C10eO8
a
cosylation products.
0
ꢀ
ꢀ
and H1 eO8 distances were 2.764 and 2.267 A for 18 and 2.844 and
2.108 A for 19, respectively). Although the tropone-fused hetero-
cycle ribonucleosides 10 and 17 have similar frameworks, except for
a tropone carbonyl group, the H10 protons of 17 and its methyl
derivative 18 are shifted downfield (1.04e1.08 ppm) in comparison
to that of 10, as shown in Table 2. The H10 protons of 19 and 20 are
downfield (0.67e0.69 ppm) from that of 14. Furthermore, 20-
deoxyuridine and 20-deoxycytidine in solution have been reported
Fig. 3. ORTEP diagram of 18. Thermal ellipsoids are drawn at the 50% probability level.
Selected atoms were numbered according to the nomenclature.
Fig. 4. ORTEP diagram of 19. Thermal ellipsoids are drawn at the 50% probability level.
Selected atoms were numbered according to the nomenclature.
to prefer the anti-conformation.17 Taking into account that the
tropone oxygen atoms (O8) of 17e20 are closer to the sugar ring
than the C2 carbonyl oxygens of pyrimidine nucleosides are, the
downfield shifts of the H10 protons of cyclohepta[b]pyrrol
Fig. 2. ORTEP diagram of 10. Thermal ellipsoids are drawn at the 50% probability level.
Selected atoms were numbered according to the nomenclature.

T. Nakazawa et al. / Tetrahedron 68 (2012) 5368e5374
5371
nucleosides and the X-ray structures of 18 and 19, described above,
4. Conclusion
indicate that 17‒20 prefer the anti-conformation in solution.
In relation to the 20-deoxyribose unit, the O50-C50eC40 side
chains of 10 and 18 are arranged in gaucheegauche conformations,
and the dihedral angles O50eC50eC40eC30 were determined to be
56.8(5)ꢁ and 55.1(5)ꢁ, respectively.18 In contrast, the O50eC50eC40
side chain of 19 is in a transegauche conformation, and the dihedral
angle was determined to be ꢀ74.7(2)ꢁ.18 For the sugar puckering,
there are three possible conformations, as shown in Fig. 5.19 10 has
an O10-endo conformation, whereas 18 has a C30-endo conforma-
tion (10: the pseudorotation phase angle (P)¼91.8ꢁ (envelope like)
and the maximum puckering amplitude (nm)¼41.4ꢁ); 18: P¼17.2ꢁ
(half-chair like) and nm¼37.6ꢁ.20 In contrast, 19 takes a C20-endo
conformation (P¼176.4ꢁ (half-chair like) and nm¼38.9ꢁ).20 It should
be noted that the O10-endo and C30-endo classes of sugar puckers of
10 and 18 are rarely found in 20-deoxyribonucleosides. The C20-
endo mode of puckering in 19 is comparable with the features of 20-
deoxyribopurines and 20-deoxyribopyrimidines.21 The bond
We synthesized hitherto unknown 20-deoxyribonucleosides
with 1H-cyclohepta[d][1,2,3]triazol-6-one and 1H-cyclohepta[b]
pyrrol-8-one as nucleobases. The reaction of 2-deoxy-3,5-di-O-(p-
toluoyl)-a-D-ribofuranosyl chloride 8 with alkali metal salts of 1H-
cyclohepta[d][1,2,3]triazol-6-one 5 in polar or slightly polar sol-
vents afforded anomeric mixtures of N2- and N1-coupling prod-
ucts, i.e., 9 (N2 coupled,
b
-), 10 (N1 coupled,
b-), 11 (N2 coupled, a-)
and 12 (N1 coupled, -). Good
a
b-stereoselectivities were achieved
using the less polar solvent DME. Furthermore, the reaction of 8
with the sodium salts of 1H-cyclohepta[b]pyrrol-8-one 6 and its 3-
methyl derivative 7 afforded the corresponding glycosylation
products 17 (N1 coupled, b-) and 18 (N1 coupled, b-), respectively.
9e12, 17 and 18 were deprotected with NaOCH3 in methanol to
afford the corresponding 20-deoxyribonucleosides 13e16, 19 and
20, respectively. The anomeric structures of 10, 18, and 19 and sugar
ring conformations (O10-endo for 10, C30-endo for 18, and C20-endo
for 19) were determined by using X-ray analysis. Compounds 13,14,
19, and 20 showed weak to no antiviral activities in comparison
with those of acyclovir (ACV) for herpes simplex virus type 1 and
herpes simplex virus type 2, although 13‒16, 19, and 20 showed no
cytotoxicity toward a lung (A549) and two colon (HT-29 and HCT-
0
0
ꢀ
lengths of sugar rings (O1 eC1 bond lengths) (1.405(5) A for 100,
0
ꢀ
ꢀ
1.417(5) A for 18, and 1.440(2) A for 19) are shorter than the C4 eO1
ꢀ
ꢀ
ꢀ
bond lengths (1.440(5) A for 10, 1.440(5) A for 18, and 1.447(3) A for
19), showing that the anomeric effect is due to hyperconjugation
[nO1
-nucleosides.22
0
/s C1 eN1] occurring in these b
*
0
116) cancer cell lines (0.01 nMe10
5. Experimental section
5.1. General
mM).
1H and 13C NMR spectra were recorded on JEOL 270 and LA-500
and BRUKER B-500 spectrometers. Chemical shift values are given
in d (ppm) relative to an internal SiMe4 standard or residual solvent,
and 1H NMR signals are expressed as s (singlet), d (doublet), t (trip-
let), q (quartet), m (multiplet), or br (broad). High resolution mass
spectra were acquired on a JEOL JMS-T100LC mass spectrometer. IR
spectra were recorded on PerkinElmer Spectrum Two FT-IR spec-
trometer. Column chromatography was carried out using Merck sil-
ica gel 60, 70e230, and 230 mesh ASTM and Daiso silica gel 1001W.
Thin layerchromatography was carried out using Merck TLC silica gel
60F254. Preparative layer chromatography was carried out using
Merck PLC plates (20 cmꢂ20 cm, Silica gel 60F254, Layer¼1 mm).
Melting points were determined with a Yanaco MP-500D melting
point apparatus. Elemental analyses were performed with Yanako
CHN Corder MT-5. All reactions described below were performed
under an argon or nitrogen atmosphere and monitored by TLC.
Fig. 5. Possible conformations of 20-deoxyribonucleosides.
3. Antiviral and anticellular activities
For pre-clinical information, we evaluated the antiviral effects of
13, 14, 19, and 20 on herpes simplex virus type 1 (HSV-1) and
herpes simplex virus type 2 (HSV-2). The antiviral activities on
HSV-1 and HSV-2 in Vero cells were determined by using plaque
reduction assays. Compounds 13, 14, 19, and 20 had weak to no
antiviral activities in comparison with those of acyclovir (ACV).
5.1.1. 2- and 1-[20-Deoxy-30,50-di-O-(p-toluoyl)-
cyclohepta[d][1,2,3]triazol-6(1H)-one (9 and 10) and 2- and 1-[20-
deoxy-30,50-di-O-(p-toluoyl)-
-ribofuranosyl]cyclohepta-[d][1,2,3]
b-D-ribofuranosyl]-
a-D
triazol-6(1H)-one (11 and 12). Entry 1, starting from the lithium salt
of 5 and 8 in anhydrous acetone.
After treatment with 50 mM solutions of 13, 14, 19, 20, and ACV, the
plaque numbers of HSV-1 decreased to approximately 75%, 100%,
85%, 85%, and 0% of the vehicle control (DMSO), respectively, where
the plaque numbers of the treatment with the vehicle control was
To a solution of the lithium salt of 5, prepared by evaporation of
a solution of 5 (0.181 g, 1.23 mmol) and LiOH$H2O (0.0517 g,
1.23 mmol) in water (3 mL) to dryness in vacuo, followed by drying
at 110 ꢁC, in anhydrous acetone (30 mL) was added 8 (0.320 g,
0.823 mmol). The mixture was stirred at room temperature for two
days. After evaporation of the reaction mixture to dryness under
reduced pressure below 50 ꢁC, the residue was dissolved in CH2Cl2
(20 mL). After filtration, the filtrate was evaporated under reduced
pressure, and the residue was loaded on a silica gel column, packed
with SiO2 deactivated with 10% H2O, and eluted with CH2Cl2/Et2O
(v:v¼95:5) to give a mixture of 9 and 11 (0.170 g, 41.3%, 9:11¼39:61)
and a mixture of 10 and 12 (0.142 g, 34.5%, 10:12¼34:66).
Entry2, startingfrom thelithium saltof5 and 8 in anhydrous DMF.
To a solution of the lithium salt of 5, prepared by evaporation of
a solution of 5 (0.174 g, 1.18 mmol) and LiOH$H2O (0.0483 g,
defined as 100%. On the other hand, after treatment with 50 mM
solutions of 13, 14, 19, 20, and ACV, the plaque numbers of HSV-2
decreased to approximately 95%, 90%, 70%, 100%, and 0% of the
vehicle control, respectively. In addition, all compounds had weak
cytotoxic activities toward Vero cells. The CC50 values of 13, 14, 19,
and 20 as well as ACV were all over 100
A lung (A549) and two colon (HT-29 and HCT-116) cancer cell
lines were treated with 0.01 nMe10 M solutions of 13e16, 19, and
mM.
m
20 for 96 h. After treatment, live cell numbers were measured and
compared with that of a non-treated control. In this assay, com-
pounds 13‒16, 19, and 20 had no effect on cell proliferation and
survival regardless of the concentration tested (IC50>10 m
M).23

5372
T. Nakazawa et al. / Tetrahedron 68 (2012) 5368e5374
1.18 mmol) in water (3 mL) to dryness in vacuo, followed by drying
at 110 ꢁC, in anhydrous DMF (15 mL) was added 8 (0.308 g,
0.792 mmol). The reaction mixture was stirred at room tempera-
ture for two days and then worked up in a similar manner to that of
entry 1, affording a mixture of 9 and 11 (0.196 g, 49.5%, 9:11¼45:55)
and a mixture of 10 and 12 (0.152 g, 38.4%, 10:12¼45:55).
Entry 3, starting from the sodium salt of 5 and 8 in anhydrous
DMF.
To a solution of the sodium salt of 5, prepared by evaporation of
a solution of 5 (0.221 g, 1.50 mmol) and 2 N aqueous NaOH
(0.75 mL) in water (2 mL) to dryness in vacuo, followed by drying at
110 ꢁC, in anhydrous DMF (30 mL) was added 8 (0.407 g,
1.05 mmol). The reaction mixture was stirred at room temperature
for two days and then worked up in a similar manner to that of
entry 1, affording a mixture of 9 and 11 (0.183 g, 34.9%, 9:11¼72:28)
and a mixture of 10 and 12 (0.241 g, 45.9%, 10:12¼69:31).
Entry 4, starting from the sodium salt of 5 and 8 in anhydrous
DME.
To a solution of the sodium salt of 5, prepared by evaporation of
a solution of 5 (0.209 g, 1.42 mmol) and 2 N aqueous NaOH
(0.71 mL) in water (2 mL) to dryness in vacuo, followed by drying at
110 ꢁC, in anhydrous dimethoxyethane (DME) (30 mL) was added 8
(0.369 g, 0.949 mmol). The reaction mixture was stirred at room
temperature for two days and then worked up in a similar manner
to that of entry 1, affording a mixture of 9 and 11 (0.285 g, 60.0%,
9:11¼98:2) and a mixture of 10 and 12 (0.121 g, 25,5%, 10:12¼95:5).
Entry 5, starting from the potassium salt of 5 and 8 in anhydrous
DME.
134.89, 130.28, 129.74, 129.59, 129.25, 129.11, 126.33, 126.26, 120.80,
87.33, 84.11, 74.40, 63.16, 36.27, 21.68, 21.61; IR (ATR) 1708 (nC]O of
ester), 1609, 1591, 1557 cmꢀ1
(nC]O and nC]C of tropone); Anal.
Calcd for C28H25O6N3: C, 67.33; H, 5.04; N, 8.41%. Found: C, 67.18; H,
4.91; N, 8.43%.
5.1.1.3. Isolation of 11. A mixture of
9 and 11 (0.311 g,
9:11¼38:62) was separated by using column chromatography with
SiO2 deactivated with 10% H2O and CH2Cl2 as an eluent. Several
eluted fractions, checked with TLC, were collected. After drying the
collected fractions, compound 11 (0.025 g) was obtained as color-
less crystals and was recrystallized from C6H6/Et2O, affording col-
orless plates: mp 137.0e137.5 ꢁC; 1H NMR (500 MHz, CDCl3):
d 7.94
(d, 2H, J¼7.9 Hz, ArH), 7.74 (d, 2H, J¼8.2 Hz, ArH), 7.56 (d, 2H,
J¼11.3 Hz, H4, H8), 7.25 (d, 2H, J¼7.9 Hz, ArH), 7.16 (d, 2H, J¼8.2 Hz,
ArH) 6.85 (d, 2H, J¼11.3 Hz, H5, H7), 6.59 (dd, 1H, J¼6.9, 1.7 Hz, H10),
5.63 (m, 1H, H30), 4.97 (m, 1H, H40), 4.69 (dd, 1H, J¼12.2, 3.7 Hz,
H50b), 4.61 (dd, 1H, J¼12.2, 4.1 Hz, H50a), 3.18 (dt, 1H, J¼15.0,
w1.7 Hz, H20b), 3.09 (dt, 1H, J¼15.0 and 6.9 Hz, H20a), 2.42 (s, 3H,
CH3), 2.40 (s, 3H, CH3). HRMS (ESIþ) m/z C28H25O6N3Na (MþNa)þ
calcd 522.16410. obsd: 522.16576.
5.1.1.4. Isolation of 12. A mixture of 10 and 12 (19 mg,
10:12¼1.0:1.1) was chromatographed on four PL plates. After re-
peated development of the plates with CH2Cl2 for 2 days, 10 (9 mg)
was obtained from the first migrating zone, and 12 (9 mg) was
obtained from second migrating zone as a waxy solid: 1H NMR
(500 MHz, CDCl3):
d
7.94 (d, 2H, J¼7.9 Hz, ArH), 7.85 (d, 1H,
To a solution of the potassium salt of 5, prepared by evaporation
of a solution of 5 (0.187 g, 1.27 mmol) and 1 N aqueous KOH
(1.27 mL) in water (2 mL) to dryness in vacuo, followed by drying at
110 ꢁC, in anhydrous DME (50 mL) was added 8 (0.329 g,
0.846 mmol). The reaction mixture was stirred at room tempera-
ture for two days and then worked up in a similar manner as that of
entry 1, affording a mixture of 9 and 11 (0.261 g, 61.7%, 9:11¼99:1)
and a mixture of 10 and 12 (0.106 g, 25.1%, 10:12¼96:4).
J¼12.2 Hz, H4 or H8), 7.82 (d, 1H, J¼12.2 Hz, H8 or H4), 7.81 (d, 2H,
J¼7.9 Hz, ArH), 7.27 (d, 2H, J¼7.9 Hz, ArH), 7.22 (d, 2H, J¼7.9 Hz,
ArH), 6.97 (dd, 1H, J¼12.2, 2.1 Hz, H5 or H7), 6.93 (dd, 1H, J¼12.2,
2.1 Hz, H7 or H5), 6.60 (dd, 1H, J¼7.3 and 1.8 Hz, H10), 5.70 (m, 1H,
H30), 4.70 (dd, 1H, J¼11.3, 3.1 Hz, H50b), 4.67 (m, 1H, H40), 4.62 (dd,
1H, J¼11.3, 3.9 Hz, H50a), 3.80 (dt, 1H, J¼15.3, 1.8 Hz, H20b), 3.12 (dt,
1H, J¼15.3, 7.3 Hz, H20a), 2.43 (s, 3H, CH3), 2.40 (s, 3H, CH3).
5.1.2. 2-(20-Deoxy-
b-D-ribofuranosyl)cyclohepta[d][1,2,3]triazol-
5.1.1.1. Isolation of 9. To a mixture of 9 and 11 (0.285 g,
9:11¼98:2) was added Et2O (20 mL). The resulting colorless crystals
of 9 were collected by filtration (0.238 g) and were recrystallized
from CH3CN to give colorless plates: mp 170.8e171.2 ꢁC; 1H NMR
6(1H)-one (13). To a solution of 9 (75 mg, 0.15 mmol) in MeOH
(2 mL) was added a solution of NaOMe in MeOH (0.0913 mmol/mL,
1.97 mL). The mixture was stirred at room temperature for one day
(TLC control) and then concentrated under reduced pressure. The
residue was separated by using column chromatography with SiO2
deactivated with 10% MeOH and with CH2Cl2 as the eluent to afford
methyl toluate (38 mg, 84%) and CH2Cl2/MeOH (v:v¼9:1) to afford
13 (41 mg, 98%) as colorless crystals. 13 was recrystallized from
CH2Cl2/MeOH, affording colorless needles: mp 127.5e128.0 ꢁC; 1H
(500 MHz, CDCl3):
d
7.96 (d, 2H, J¼8.2 Hz, ArH), 7.90 (d, 2H,
J¼8.2 Hz, ArH), 7.50 (d, 2H, J¼12.2 Hz, H4, H8), 7.28 (d, 2H, J¼8.2 Hz,
ArH), 7.19 (d, 2H, J¼8.2 Hz, ArH), 6.82 (d, 2H, J¼12.2 Hz, H5, H7),
6.60 (t,1H, Jz6.0 Hz, H10), 5.96 (m, 1H, H30), 4.72 (m,1H, H50b), 4.69
(m, 1H, H40), 4.53 (m, 1H, H50a), 3.43 (ddd, 1H, J¼14.3, 6.7, 5.2 Hz,
H20b), 2.82 (ddd, 1H, J¼14.3, 6.7, 4.9 Hz, H20a), 2.44 (s, 3H, CH3), 2.40
NMR (500 MHz, DMSO-d6):
d
7.80 (dd, 2H, J¼12.2, 1.2 Hz, H4, H8),
(s, 3H, CH3); 13C NMR (125 MHz, CDCl3):
d
188.18, 166.03, 165.85,
6.79 (dd, 2H, J¼12.2, 1.2 Hz, H5, H7), 6.46 (dd,1H, J¼6.7, 4.3 Hz, H10),
5.45 (d,1H, J¼4.9 Hz, OH30), 4.78 (t,1H, J¼5.5 Hz, OH50), 4.50 (m,1H,
H30), 3.89 (m,1H, H40), 3.51 (m,1H, H50b), 3.43 (m,1H, H50a), 2.83 (m,
145.89, 144.43, 143.89, 136.14, 129.74, 129.22, 129.02, 128.61, 126.80,
126.35, 92.75, 83.62, 74.49, 63.55, 37.41, 21.68, 21.62; IR (ATR) 1723,
1703 (nC]O of ester), 1626, 1608, 1598 cmꢀ1
(nC]O and nC]C of tro-
1 H, H20b), 2.45 (m,1H, H20a); 13C NMR (125 MHz, CD3OD):
d
190.38,
pone); Anal. Calcd for C28H25O6N3: C, 67.33; H, 5.04; N, 8.41%.
Found: C, 67.56; H, 4.95; N, 8.45%.
147.07,136.69,131.11, 94.65, 90.14, 72.44, 63.77, 40.95; IR (ATR) 3308
(OH),1621,1583 cmꢀ1
(
nC]O and nC]C of tropone); HRMS (ESIþ) m/z
C12H13N3O4Na (MþNa)þ calcd 286.08038, obsd 286.08039.
5.1.1.2. Isolation of 10. A mixture of 10 and 12 (0.121 g,
10:12¼95:5) was recrystallized from C6H5/Et2O to afford 10
(0.068 g) as pale yellow prisms: mp 148.7e149.8 ꢁC; 1H NMR
5.1.3. 1-(20-Deoxy-
b-D-ribofuranosyl)cyclohepta[d][1,2,3]triazol-
6(1H)-one (14). To a solution of 10 (74 mg, 0.148 mmol) in MeOH
(2 mL) was added a solution of NaOMe in MeOH (0.0913 mmol/mL
1.95 mL). The mixture was stirred at room temperature for one day
(TLC control). The reaction mixture was worked up in a manner
similar to that of 13, affording methyl toluate (33 mg, 74%) and 14
(39 mg, 98%) as colorless crystals, which was recrystallized from
EtOAc to afford colorless needles: mp 135.0e136.5 ꢁC; 1H NMR
(500 MHz, CDCl3):
d
7.96 (d, 2H, J¼7.9 Hz, ArH), 7.78 (d, 2H, J¼7.9 Hz,
ArH), 7.75 (d, 1H, J¼11.9 Hz, H4 or H8), 7.66 (d, 1H, J¼12.2 Hz, H8 or
H4), 7.28 (d, 2H, J¼7.9 Hz, ArH), 7.20 (d, 2H, J¼7.9 Hz, ArH) 6.89 (dd,
J¼12.2, 2.1 Hz, 1H, H7 or H5), 6.86 (dd, J¼11.9, 2.1 Hz, 1H, H5 or H7),
6.57 (t, 1H, Jz6.0 Hz, H10), 5.88 (m, 1H, H30), 4.71 (m, 1H, H40), 4.57
(dd, 1H, J¼12.2, 4.3 Hz, H50b), 4.39 (dd, 1H, J¼12.2, 4.9 Hz, H50a),
3.90 (dt, 1H, J¼14.3, 6.1 Hz, H20b), 2.93 (ddd, 1H, J¼14.3, 6.1, 4.1 Hz,
H20a), 2.44 (s, 3H, CH3), 2.40 (s, 3H, CH3); 13C NMR (125 MHz,
(500 MHz, DMSO-d6):
1H, J¼12.2 Hz, H8 or H4), 6.91 (dd, 1H, J¼12.2, 2.1 Hz, H5 or H7),
6.81 (dd, 1H, J¼12.2, 2.1 Hz, H7 or H5), 6.70 (dd, 1H, J¼6.4, 4.9 Hz,
d
7.98 (d, 1H, J¼12.2 Hz, H4 or H8), 7.92 (d,
CDCl3):
d 187.28, 165.81, 146.86, 144.52, 144.02, 138.09, 135.28,

T. Nakazawa et al. / Tetrahedron 68 (2012) 5368e5374
5373
H10), 5.47 (d, 1H, J¼4.6 Hz, OH30), 4.75 (t, 1H, J¼5.3 Hz, OH50), 4.50
(m,1H, H30), 3.92 (m,1H, H40), 3.43 (m,1H, H50b), 3.26 (m,1H, H50a),
3.14 (m, 1H, H20b), 2.45 (m, 1H, H20a); 13C NMR (125 MHz, CD3OD):
1.53 mmol) and NaOEt (1.06 mmol/mL EtOH solution, 1.5 mL) in
absolute EtOH (5 mL) to dryness, followed by drying at 100 ꢁC, in
anhydrous DME (20 mL) was added 8 (0.423 g, 1.09 mmol). The
reaction mixture was stirred for two days at room temperature and
then filtered. The filtrate was evaporated under reduced pressure.
The residue was separated by using column chromatography with
SiO2 deactivated with 10% H2O and with CH2Cl2 as the eluent to give
18 (0.392 g, 70.3% for compound 8 used) as colorless crystals and
with CH2Cl2/EtOAc (v:v¼9:1) to recover the remaining 7 (0.111 g,
45.7% for compound 7 used). Compound 18 was recrystallized from
MeOH to give colorless needles: mp 151.9e152.3 ꢁC; 1H NMR
d
189.78, 147.81, 138.29, 136.68, 135.87, 132.37, 124.23, 90.24, 88.68,
72.30, 63.28, 40.03; IR (ATR) 3310 (OH), 1604, 1548 cmꢀ1
(nC]O and
nC]C of tropone); HRMS (ESIþ) m/z C12H13N3O4Na (MþNa)þ calcd
286.08038, obsd 286.07619.
5.1.4. 2-(20-Deoxy-
a-D-ribofuranosyl)cyclohepta[d][1,2,3]triazol-
6(1H)-one (15). A solution of NaOMe in MeOH (0.045 mmol/mL,
0.42 mL) was added to 11 (7.8 mg, 0.016 mmol). The mixture was
stirred at room temperature for one day (TLC control). The reaction
mixture was worked up in a manner similar to that of 13, affording
15 (2.3 mg, 55%) as a colorless waxy solid: 1H NMR (500 MHz,
(500 MHz, CDCl3):
d
7.98 (d, 2H, J¼8.2 Hz, ArH), 7.93 (d, 2H, J¼8.4 Hz,
ArH), 7.65 (br. t, 1H, Jz6.6 Hz, H10), 7.59 (s, 1H, H2), 7.46 (d, 1H,
J¼10.7 Hz, H4), 7.28 (d, 2H, J¼8.4 Hz, ArH), 7.22 (d, 2H, J¼8.2 Hz,
ArH), 7.15 (dd,1H, J¼12.5 and 8.2 Hz, H6), 7.03 (d,1H, J¼12.5 Hz, H7),
6.75 (dd, 1H, J¼10.7, 8.2 Hz, H5), 5.62 (m, 1H, H30), 4.80 (dd, 1H,
J¼12.1, 3.2 Hz, H50b), 4.70 (dd, 1H, J¼12.1, 3.6 Hz, H50a), 4.61 (m, 1H,
H40), 3.05 (ddd, 1H, J¼14.3, 5.6, 2.7 Hz, H20b), 2.43 (s, 3H, CH3), 2.42
(m,1H, H20a), 2.40 (s, 3H, CH3), 2.14 (s, 3H, CH3); 13C NMR (125 MHz,
CD3OD):
d
7.82 (d, 2H, J¼12.1 Hz, H4, H8), 6.87 (d, 2H, J¼12.1 Hz, H5,
H7), 6.47 (dd, 1H, J¼7.3, 3.8 Hz, H10), 4.40 (m, 1H, H30), 4.25 (m, 1H,
H40), 3.78 (dd, 1H, J¼12.2, 3.1 Hz, H50b), 3.66 (dd, 1H, J¼12.2, 4.6 Hz,
H50a), 2.93 (dt, 1H, J¼14.2, 7.6 Hz, H20b), 2.75 (ddd, 1H, J¼14.2, 5.1,
3.8 Hz, H20a); HRMS (ESIþ) m/z C12H13N3O4Na (MþNa)þ calcd
286.08038, obsd 286.08020.
CDCl3):
d 177.84, 166.27, 166.19, 144.25, 144.07, 136.81, 135.46,
134.65, 130.81, 130.55, 129.87, 129.66, 129.22, 129.20, 126.83, 126.57,
124.74, 123.01, 118.68, 88.74, 82.76, 74.63, 64.18, 41.74, 21.71,
21.67, 9.80; IR (ATR) 1712 (nC]O of ester), 1629, 1612, 1564,
5.1.5. 1-(20-Deoxy-
a-D-ribofuranosyl)cyclohepta[d][1,2,3]triazol-
6(1H)-one (16). A solution of NaOMe in MeOH (0.060 mmol/mL
0.55 mL) was added to 12 (13.8 mg, 0.0276 mmol). The mixture was
stirred at room temperature for one day (TLC control). The reaction
mixture was worked up in a manner similar to that of 13, affording
methyl toluate (8.3 mg, 95%) and 16 (5.4 mg, 74%) as a colorless oil:
1551 cmꢀ1
(nC]O and nC]C of tropone); Anal. Calcd for C31H29O6N: C,
72.78; H, 5.71; N, 2.74%. Found: C, 72.67; H, 5.74; N, 2.75%.
5.1.8. 1-(20-Deoxy-
b-D-ribofuranosyl)cyclohepta[b]pyrrol-8(1H)-one
1H NMR (270 MHz, CD3OD):
d
8.09 (d, 1H, J¼12.2 Hz, H4 or H8), 7.94
(19). To a solution of 17 (75 mg, 0.151 mmol) in anhydrous MeOH
(2 mL) was added a solution of NaOMe in MeOH (0.0913 mmol/mL,
1.98 mL). The mixture was stirred at room temperature for one day
(TCL control). The reaction mixture was worked up in a manner
similar to that of 13, affording methyl toluate (42 mg, 93%) and 19
(35 mg, 90%) as colorless prisms: mp 182.0e183.5 ꢁC; 1H NMR
(d, 1H, J¼12.0 Hz, H8 or H4), 6.99 (dd, 1H, J¼12.2, 2.3 Hz, H5 or H7),
6.92 (dd, 1H, J¼12.0, 2.3 Hz, H7 or H5), 6.68 (dd, 1H, J¼7.2, 3.8 Hz,
H10), 4.46 (m,1H, H30), 4.09 (m,1H, H40), 3.76 (dd,1H, J¼12.2, 3.2 Hz,
H50b), 3.67 (dd, 1H, J¼12.2, 4.4 Hz, H50a), 3.14 (ddd, 1 H, J¼14.2, 4.6,
3.8 Hz, H20b), 2.94 (dt, 1H, J¼14.2, 7.2 Hz, H20a); HRMS (ESIþ) m/z
C12H13N3O4Na (MþNa)þ calcd 286.08038, obsd 286.08130.
(500 MHz, DMSO-d6):
d
8.07 (d, 1H, J¼2.4 Hz, H2), 7.60 (d, 1H,
J¼10.7 Hz, H4), 7.37 (br. t, 1H, Jz5.8 Hz, H10), 7.19 (dd, 1H, J¼12.5,
8.5 Hz, H6), 6.88 (d, 1H, J¼12.5 Hz, H7), 6.77 (dd, 1H, J¼10.7, 8.5 Hz,
H5), 6.75 (d, J¼2.4 Hz, H3), 5.26 (d, 1H, J¼4.0 Hz, OH30), 5.07 (t,
J¼4.7 Hz, OH50), 4.25 (m, 1H, H30), 3.86 (m, 1H, H40), 3.65 (m, 1H,
H50b), 3.60 (m, 1H, H50a), 2.40 (m, 1H, H20b), 2.09 (m, 1H, H20a); 13C
5.1.6. 1-[20-Deoxy-30,50-di-O-(p-toluoyl)-
b-D-ribofuranosyl]cyclo-
hepta[b]pyrrol-8(1H)-one (17). To a solution of the sodium salt of 6,
prepared by evaporation of a solution of 6 (0.182 g, 1.25 mmol) and
NaOC2H5 (1.06 mmol/mL EtOH solution, 1.2 mL) in absolute EtOH
(5 mL) to dryness, followed by drying at 100 ꢁC, in anhydrous DME
(30 mL) was added 8 (0.348 g, 0.895 mmol). The reaction mixture
was stirred for two days at room temperature and then filtered. The
filtrate was evaporated under reduced pressure. The residue was
separated by using column chromatography with SiO2 deactivated
with 10% H2O and with CH2Cl2 as the eluent to afford 17 (0.291 g,
65.2% for compound 8 used) as a colorless oil and with CH2Cl2/Et2O
(v:v¼9:1) to recover the remaining 6 (0.071 g, 39.0% for compound
NMR (125 MHz, DMSO-d6):
d 176.92, 136.32, 134.53, 134.15, 133.28,
131.59,127.61,123.44,110.94, 87.51, 87.34, 69.58, 61.10, 43.53; IR (ATR)
3288 (OH), 1628, 1567, 1547 cmꢀ1
(nC]O and nC]C of tropone); HRMS
(ESIþ) m/z C14H15NO4Na (MþNa)þ calcd 284.08988, obsd 284.08921.
5.1.9. 1-(20-Deoxy-
b-D-ribofuranosyl)-3-methylcyclohepta[b]pyrrol-
8(1H)-one (20). To a solution of 18 (80 mg, 0.156 mmol) in anhy-
drous MeOH (2 mL) was added a solution of NaOMe in MeOH
(0.0913 mmol/mL, 2.05 mL). The mixture was stirred at room tem-
perature for one day (TLC control). The reaction mixture was worked
up in a manner similar to that of 13, affording methyl toluate (31 mg,
66%) and 20 (29 mg, 67%) as colorless needles: mp 186.5e188.0 ꢁC;
6 used). Compound 17: 1H NMR (500 MHz, CDCl3):
d 7.99 (d, 2H,
J¼8.2 Hz, ArH), 7.90 (d, 2H, J¼8.2 Hz, ArH), 7.81 (d,1H, J¼3.1 Hz, H2),
7.61 (br. t, 1H, Jz6.6 Hz, H10), 7.47 (d, 1H, J¼10.7 Hz, H4), 7.26 (d, 2H,
J¼8.2 Hz, ArH), 7.21 (d, 2H, J¼8.2 Hz, ArH), 7.13 (dd, 1H, J¼12.5,
8.2 Hz, H6), 7.04 (d, 1H, J¼12.5 Hz, H7), 6.72 (dd, 1H, J¼10.7, 8.2 Hz,
H5), 6.56 (d, J¼3.1 Hz, H3), 5.60 (m, 1H, H30), 4.75 (dd, 1H, J¼12.0,
3.5 Hz, H50b), 4.73 (dd, 1H, J¼12.0, 3.8 Hz, H50a), 4.64 (m, 1H, H40),
3.12 (ddd, 1H, J¼14.3, 5.6, 2.6 Hz, H20b), 2.43 (m, 1H, H20a), 2.43 (s,
1H NMR (500 MHz, DMSO-d6):
d 7.87 (s, 1H, H2), 7.55 (d, 1H,
J¼11.0 Hz, H4), 7.39 (br. t, 1H, Jz6.3 Hz, H10), 7.20 (dd, 1H, J¼12.5,
8.2 Hz, H6), 6.87 (d, 1H, J¼12.5 Hz, H7), 6.80 (dd, 1H, J¼11.0, 8.2 Hz,
H5), 5.24 (d,1H, J¼4.0 Hz, OH30), 5.04 (t,1H, J¼5.2 Hz, OH50), 4.24 (m,
1H, H30), 3.78 (m, 1H, H40), 3.62 (m, 2H, H50a, H50b), 2.36 (m, 1H,
H20b), 2.24 (s, 3H, CH3), 2.08 (m, 1H, H20a); 13C NMR (125 MHz,
3H, CH3), 2.40 (s, 3H, CH3), 13C NMR (125 MHz, CDCl3):
d 177.89,
166.21, 166.12, 144.22, 144.03, 136.84, 134.91, 134.63, 133.23, 132.25,
129.83, 129.63, 129.17, 129.16, 126.72, 126.51, 126.10, 123.70, 111.06,
89.13, 82.87, 74.65, 64.25, 41.83, 21.67, 21.62; IR (ATR) 1715 (nC]O of
DMSO-d6):
d 176.80, 136.25, 134.66, 134.49, 130.57, 129.93, 126.06,
122.82, 117.89, 87.43, 86.89, 69.84, 61.29, 43.29, 9.72; IR (ATR) 3300
ester),1631,1612,1573,1555 cmꢀ1
(
nC]O and nC]C of tropone); Anal.
(OH),1604,1548 cmꢀ1
(
nC]O and nC]C of tropone); HRMS (ESIþ) m/z
Calcd for C30H27O6N: C, 72.42; H, 5.47; N, 2.82%. Found: C, 72.04; H,
5.40; N, 2.59%.
C15H17NO4Na (MþNa)þ calcd 298.10553, obsd 298.10411.
5.2. X-ray crystallography
5.1.7. 1-[20-Deoxy-30,50-di-O-(p-toluoyl)-
b-D-ribofuranosyl]-3-
methylcyclohepta[b]pyrrol-8(1H)-one (18). To a solution of the so-
dium salt of 7, prepared by evaporation of a solution of 7 (0.243 g,
X-ray data were acquired on a Bruker Smart APEX diffractom-
eter equipped with
a CCD area detector with graphite-

5374
T. Nakazawa et al. / Tetrahedron 68 (2012) 5368e5374
ꢀ
monochromated Mo K
a
radiation (
l
¼0.71073 A). The structure was
Prof. Masayoshi Takase, and Prof. Kotohira Nomura (Graduate
School of Science and Engineering, Tokyo Metropolitan University)
for their kind supports. The authors also thank Prof. Noriaki Min-
akawa (Institute of Health Biosciences, The University of Tokush-
ima) for experimental discussions.
solved by using direct methods (SHELXTL) and refined by using full-
matrix least-squares method on F2 (SHELXL-97). Non-hydrogen
atoms were refined anisotropically, and hydrogen atoms were
placed using AFIX instructions. Crystallography data has been de-
posited at the Cambridge Crystallography Data Center with de-
position number of 869269, 869270, and 869271 for 10, 18, and 19.
Copies of this information may be obtained free of charge from The
CCDC, 12 Union road, Cambridge CB2 1EZ, UK (fax: þ44 1223
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.tet.2012.04.109.
336033;
e-mail:
deposit@ccdc.cam.ac.uk
or
http://
www.ccdc.cam.ac.uk).
Crystal data for 10. C28H25N3O6, M¼499.51; orthorhombic, space
group P212121; a¼6.1410(6), b¼16.8267(16), c¼23.706(2),
a
¼90ꢁ,
References and notes
3
ꢁ
ꢀ
b
¼90ꢁ,
g
¼90 , V¼2449.6(4) A ; Dc (Z¼4)¼1.354 g cmꢀ3; T¼293 K,
1. (a) Nishiwaki, T.; Abe, N. Heterocycles 1981, 15, 547; (b) Kimura, M. Yuki Gosei
Kagaku Kyoukaishi 1981, 39, 690; (c) Abe, N. Trend in Heterocyclic Chemistry
2001, 7, 25 Research Trends; (d) Abe, N. Recent Res. Devel. Org. & Bioorg. Chem.
2001, 4, 17; (e) Abe, N.; Gunji, T. Heterocycles 2010, 82, 201.
2. (a) Fischer, G. Advan. Heterocycl. Chem. 1995, 64, 81; (b) Fischer, G. Advan.
Heterocycl. Chem. 1996, 66, 285.
3. Ohno, M.; Yagisawa, N.; Shibahara, S.; Kondo, S.; Maeda, K.; Umezawa, H. J. Am.
Chem. Soc. 1974, 96, 4327.
4. (a) Nishiwaki, T.; Abe, N. J. Chem. Research (s) 1984, 264; (b) Nishiwaki, T.; Fukui,
T. J. Chem. Research (s) 1986, 288.
5. (a) Xia, Y.; Qu, F.; Peng, L. Mini. Rev. Med. Chem. 2010, 10, 806; (b) Gadhave, P. P.;
Dighe, N. S.; Pattan, S. R.; Deotarse, P.; Musmade, D. S.; Shete, R. V. Ann. Biol. Res.
2010, 1, 82.
6. (a) Bellina, F.; Rossi, R. Tetrahedron 2006, 62, 7213; (b) Saracoglu, N. Bioactive
Heterocycles V Top. Heterocycl. Chem. 2007, 11, 1; (c) Ono, N. Heterocycles 2008,
75, 243.
7. (a) Miura, Y.; Noguchi, T.; Nozoe, T. Bull. Soc. Chim. Biol. 1956, 38, 1441; (b)
Miura, Y.; Okamoto, N.; Shimamune, A. Seikagaku 1960, 32, 744; (c) Yamazaki,
M.; Satoh, Y.; Ito, S. Yakugaku Zasshi. 1988, 108, 754; Chem. Abstr. 1989, 110,
53542.
8981 collected reflections, 3492 reflections with I>2
R1¼0.0509, wR2¼0.112.
s(I),
Crystal data for 18. C31H29NO6, M¼511.55; orthorhombic, space
group P212121; a¼5.8101(12), b¼14.674(3), c¼30.356(6),
a
¼90ꢁ,
3
ꢁ
ꢀ
b
¼90ꢁ,
g
¼90 , V¼2588.9(9) A ; Dc (Z¼4)¼1.313 g cmꢀ3; T¼293 K,
9459 collected reflections, 3734 reflections with I>2
R1¼0.0449, wR2¼0.110.
s(I),
Crystal data for 19. C14H15NO4, M¼261.27; monoclinic, space
group P21; a¼11.733(4), b¼4.6709(15), c¼12.052(4),
a
¼90ꢁ,
3
ꢀ
ꢀ3
ꢁ
b
¼112.443(5)ꢁ,
g
¼90 , V¼610.5(3) A ; Dc (Z¼2)¼1.345 g cm
;
T¼293 K, 2624 collected reflections, 1655 reflections with I>2
R1¼0.0326, wR2¼0.0837.
s
(I),
5.3. Determination of antiviral and anticellular activities
8. (a) Takagi, H.; Kobayashi, S.; Iizuka, Y.; Mori, M. Sankyo Kenkyusho Nempo 1969,
21, 72; Chem. Abstr. 1970, 72, 130936; (b) Goodie, A. C.; Ward, R. W. Eur. Patent
24,807, 1981; Chem. Abstr. 1981, 95, 97583. (c) Goudie, A. C.; Ward, R. W.;
Rosenberg, H. E. Eur. Patent 35,853, 1981; Chem. Abstr. 1982, 96, 35223.
9. Komatsu, H.; Oikawa, T.; Ishibashi, H. Yuki Gosei Kagaku Kyoukaishi 2005,
63, 594.
10. (a) Hoffer, M. Chem. Ber. 1960, 93, 2777; (b) Kazimierezuk, Z.; Revankar, G. R.;
Robins, R. K. Nucleic Acids Res. 1984, 12, 1179; (c) Kazimierezuk, Z.; Cottam, H. B.;
Revankar, G. R.; Robins, R. K. J. Am. Chem. Soc. 1984, 106, 6379; (d) Kawakami, H.;
Matsushita, H.; Naoi, Y.; Itoh, K.; Yoshikoshi, H. Chem. Lett. 1989, 235; (e) Wang,
Z. eX.; Duan, W.; Wiebe, L. I.; Balzarini, J.; De Clercq, E.; Knaus, E. E. Nucleosides,
Nucleotides, Nucleic Acids 2001, 20, 11.
11. Nozoe, T.; Ito, S.; Matsui, K. Proc. Japan Acad. 1954, 30, 313.
12. Sunagawa, G.; Soma, N.; Nakao, H.; Matsumoto, Y. Yakugaku Zasshi 1961, 81,
1799.
13. From supplementary data are available X-ray structures of 10, 18, and 19, for
which the atoms were numbered according to cif files.
14. (a) Kazimierezuk, Z.; Seela, F. Justus Liebigs Ann. Chem. 1990, 647; (b) Aoyama, H.
Bull. Chem. Soc. Jpn. 1987, 60, 2073.
15. Hubbard, A. J.; Jones, A. S.; Walker, R. T. Nucleic Acids Res. 1984, 12, 6827.
16. Nakazawa, T.; Murata, I. Angew. Chem. 1975, 87, 742 Angew. Chem. Int. Ed. Engl.
1975, 14, 711.
17. Davies, D. B. Progress in NMR Spectroscopy 1978, 12, 135.
18. The C50eO50 bond can rotate relative to the sugar ring assuming three possible
conformations, designated gauche-gauche, gauche-trans, and trans-gauche
depending on whether the torsion angle O50-C50eC40eC30 is about þ60ꢁ,
180ꢁ or ꢀ60ꢁ Saenger, W. Angew. Chem. 1973, 85, 680 Angew. Chem. Int. Ed. Engl.
1973, 12, 591.
The antiviral activities of the compounds against the HF strain of
herpes simplex virus type 1 (HSV-1) and SAVAGE strain of herpes
simplex virus type 2 (HSV-2) in Vero cells were determined by
using a plaque reduction assay. Vero cells were cultivated with
DMEM supplemented with 10% fetal bovine serum (DMEM-10%
FBS). Vero cells seeded in a 6-well tissue culture plate were culti-
vated for two days, and then the cell monolayers were washed once
with a phosphate buffered saline solution (PBS). Vero cell sheets
were inoculated with about 100 PFU of HSV-1 or HSV-2 in 0.2 mL of
DMEM-0%FBS. After adsorption for 60 min, the inoculum was re-
moved, and HSV-infected cell sheets in duplicated wells were fed
with DMEM-10%FBS containing 0.5% methylcellulose and serially
diluted test compounds. After incubating for 2e3 days in a 5% CO2
humidified incubator at 37 ꢁC, the maintenance medium was re-
moved. Then the cell sheets were stained with 1% crystal violet in
50% methanol, and the plaque numbers were counted. The plaque
number for the treatment with the vehicle control (DMSO) was
defined as 100%. Determination of anticellular activities of
compounds.
Cells were seeded in a 96-well tissue culture plate at 1ꢂ104 cells
per well. After 1 day, the cells were fed again with DMEM-10%FBS
containing an appropriate amount of the test compound. After 2
days, the number of viable cells was estimated by using a cell-
counting kit-8 (Dojindo). The optical density of the sample was
measured at 450 nm with a microplate spectrophotometer and
expressed as a percentage of the value of the untreated cells (de-
fined as 100%). The value of CC50, a 50% cytotoxic concentration of
drug, was calculated from the plot of the drug concentration versus
the percentage of live cells.
19. The deoxyribose ring is arranged in an envelope or half-chair conformation.
Substituent effe0cts lead to preference of those conformations, in which the
0
0
ꢀ
atoms C(2 ), C(3 ), and O(1 ) are displaced about 0.5 A from the plane through
the other four atoms. Atoms lying on the same side of this plane as C(50) were
assigned to be endo, and those on the other side are exo Jardetzky, C. D. J. Am.
Chem. Soc. 1960, 82, 229.
20. Calculated from tan P¼[(
n
4þ
n1)ꢀ(
n3þn0)]/2
n
2(sin 36ꢁþsin 72ꢁ) and
n2¼nmcos
P Altona, C.; Sundaralingam, M. J. Am. Chem. Soc. 1972, 94, 8205.
21. (a) Sundaralingam, M. Ann. N. Y. Acad. Sci. 1975, 255, 3; (b) Sundaralingam, M. In
Conformations of Biological Molecules and Polymers; Bergmann, V. E. D., Pullman,
B., Eds.; The Jerusalem Symposia on Quantum Chemistry and Biochemistry;
1973; vol. 5, p 417.
22. (a) Deslongchamps, P. In Stereoelectronic Effect in Organic Chemistry;
Baldwin, J. E., Ed.; Pergamon: Oxford, 1983; (b) Thibaudeau, C.; Acharya,
P.; Chattopadhyaya, J. In Stereoelectronic Effects in Nucleosides & Nucleotides
and Their Structural Implications; Uppsala University: Uppsala-Sweden,
2005.
Acknowledgements
The authors thank Prof. Haruki Niwa (Faculty of Electro-
communications, The University of Electro-communications)
for the measurement of high resolution mass spectra and
Dr. Yoshiyuki Kuwatani, Dr. Hideyuki Shimizu, Dr. Fatema Sultana,
23. The assay on these cancer cell lines was conducted by Yakult Honsha Co. LTD,
Ginza 7-16-21, Chuou-ku, Tokyo 104-0061, Japan.