Synthesis of highly cytotoxic tiazofurin mimics bearing a 2,3-anhydro function in the furanose ring

Article abstract of DOI:10.1016/j.tet.2009.06.100

This paper describes a divergent de novo synthesis of 2-(2,3-anhydro-β-d-ribofuranosyl)thiazole-4-carboxamide (2′,3′-anhydro-tiazofurin) and the corresponding α- and β-homo-C-nucleosides. The synthetic approach was based on a multistep transformation of d-glucose into suitably protected aldonthioamides followed by their subsequent cyclocondensation with ethyl bromopyruvate to form the thiazole ring. Antiproliferative activity of the target molecules is reported against several human tumour cell lines.

Full text of DOI:10.1016/j.tet.2009.06.100

Tetrahedron 65 (2009) 7637–7645
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
Synthesis of highly cytotoxic tiazofurin mimics bearing a 2,3-anhydro
function in the furanose ring
,
a
a
b
b
Mirjana Popsavin a , Sasa Spaic , Milos Svircev , Vesna Kojic , Gordana Bogdanovic ,
*
ˇ
´
ˇ
ˇ
´
´
a
a
´
Vjera Pejanovic , Velimir Popsavin
a
´
Department of Chemistry, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad, Serbia
b Oncology Institute of Vovodina, Institutski put 4, 21204 Sremska Kamenica, Serbia
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 1 April 2009
Received in revised form 10 June 2009
Accepted 25 June 2009
Available online 2 July 2009
This paper describes a divergent de novo synthesis of 2-(2,3-anhydro-
b
-
D
-ribofuranosyl)thiazole-4-car-
-homo-C-nucleosides. The synthetic
D-glucose into suitably protected aldonthioamides
boxamide (20,30-anhydro-tiazofurin) and the corresponding
a- and b
approach was based on a multistep transformation of
followed by their subsequent cyclocondensation with ethyl bromopyruvate to form the thiazole ring.
Antiproliferative activity of the target molecules is reported against several human tumour cell lines.
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
dinucleotide, which induces the shutdown of guanylate synthesis.5
Despite the remarkable efficacy of 1, lack of specificity and occa-
C-Nucleosides are important targets in synthetic organic
chemistry due to their high potential value as bioactive molecules
and biochemical probes.1 A number of these nucleoside analogues
have been found to exhibit potent antiviral or antitumour activities.
Remarkable among them is tiazofurin (1, Fig. 1), a synthetic C-nu-
cleoside that shows antitumour activity in a variety of tumour
systems.2 In phase II clinical trials, it induced haematological re-
sponses in patients with acute myelogenous leukaemia, or chronic
myeloid leukaemia in blast crisis.3 Accordingly, tiazofurin has re-
cently been approved as an orphan drug for treatment of these
malignant diseases. The biological activity of tiazofurin derives
from a combination of cytotoxicity and maturation-inducing ac-
tivities.4 Both effects are attributed to inhibition of inosine 50-
monophosphate dehydrogenase (IMPDH) by the tiazofurin adenine
sional toxicity remains a problem in its clinical use.2 In order to
provide an access to derivatives of reduced toxicity, a number of
tiazofurin analogues have been synthesized and evaluated for their
antitumour activities.6 In the course of our recent program directed
towards total syntheses of tiazofurin analogues with modified
sugar moieties, we have recently disclosed the synthesis of a series
of novel b-D-ribofuranosyl-thiazoles that showed potent and se-
lective antiproliferative activities against a number of tumour cell
lines, but were devoid of any significant toxicity against the normal
foetal lung fibroblasts (MRC-5).7 As an extension of these studies,
our next endeavour was focused on the synthesis of hitherto un-
known tiazofurin derivative 2 (20,30-anhydro-tiazofurin), as well as
its homologue 3 having the 20,30-anhydro function in the furanose
ring. Synthesis and biological activity of a number of nucleoside
analogues with 20,30-anhydrofuranosyl sugar moieties has been
reported.8 Some of the results indicate that 20,30-anhydro-nucleo-
sides serve as DNA (or RNA) polymerase termination substrates,
that might be of use for development of new antitumour agents.
Herein we report on the synthesis of tiazofurin analogues 2 and 3
along with their effects on the proliferation of selected human tu-
mour cell lines.9
O
H2N
H2N
H2N
O
N
O
S
N
HO
HO
N
HO
O
O
O
S
S
OH
HO
1 (Tiazofurin)
O
O
3
2. Results and discussion
2
Figure 1. Tiazofurin (1) and the targeted analogues 2 and 3.
Our strategy to synthesise the target C-nucleosides 2 and 3 was
to synthesize the ribofuranosyl thioamides 8 (Scheme 1) and 22
(Scheme 3) as key intermediates and then to cyclocondense them
with ethyl bromopyruvate to form the thiazole ring. An alternative
strategy for the formation of thiazole rings involved direct
* Corresponding author. Tel.: þ381 21 485 27 67; fax: þ381 21 454 065.
E-mail address: mpopsavin@ih.ns.ac.yu (M. Popsavin).
0040-4020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2009.06.100

7638
M. Popsavin et al. / Tetrahedron 65 (2009) 7637–7645
cyclocondensation of cysteine ethyl ester hydrochloride with ap-
propriate aldononitriles in presence of triethylamine according to
a previous report.10
that the former two-step sequence based on the Hantzsch cycli-
zation of thioamide 8 with ethyl bromopyruvate represents a more
convenient route towards the key intermediate 9, since it provided
a considerably higher overall yield (39% from 7) compared to the
last method based on the cyclocondensation of cysteine ethyl ester
hydrochloride with nitrile 7 (23% from 7). Treatment of 9 with
methanolic ammonia provided the target 2 as a result of successive
ester aminolysis and debenzoylation, followed by concomitant
epoxide ring closure. Target compound 2 was thus prepared in 18%
overall yield calculated from the starting material 4 (6 steps).
For the preparation of homo-C-nucleoside 3 the one carbon
homologue of 7 is needed. It was assumed that the requisite in-
termediate may be accessed by nucleophilic displacement of a pri-
mary sulfonyloxy group with the cyanide anion in a suitably
BzO
BzO
R
O
O
O
5
2
3
1
a
6
O
4
BzO
BzO
OMs
OMs
5 R = O
6 R = NHOH
4
b
c
BzO
BzO
O
S
O
CN
d
functionalized 2,5-anhydro-D-glucitol derivative. Accordingly, the
NH2
2,5-anhydride 13 was envisaged not only as a convenient model
compound, but also as a possible intermediate for the preparation
of the opposite enantiomer of 3 (ent-3, Scheme 2). The rationale
underlying the preparation of ent-3 arises from the fact that en-
antiomers of certain biologically active nucleoside analogues very
often exhibit improved potencies or even novel activities
altogether.13
OMs
BzO
BzO
OMs
8
7
e
f
EtO
EtO
S
O
O
N
g
h
BzO
N
BzO
O
O
MsO
O
MsO
O
S
O
O
a
O
OMs
BzO
OMs
BzO
BzO
BzO
OMs
OMs
9
10
11
12
+
b
H2N
EtO
S
O
4
O
HO
N
N
BzO
NC
OBz
OH
O
MsO
4'
3'
1'
2'
5
5'
O
O
2
O
c or d
S
O
2
OMs
O
BzO
9a
14
13
Scheme 1. Reagents and conditions: (a) 4:1 TFA–6 M HCl, 4 ꢀC, 120 h; (b) NH2OH $ HCl,
NaOAc, EtOH, CH2Cl2, rt, 24 h; (c) MsCl, Py, ꢁ15 ꢀC, 0.5 h, then rt, 2 h, 66% from 4; (d) H2S,
Py, rt, 4 h, 90%; (e) BrCH2COCO2Et, EtOH, 80 ꢀC, 50 min, 43% of 9, 10% of 9a; (f) cysteine
ethyl ester hydrochloride, MeOH, Et3N, rt, 2 h; (g) BrCCl3, DBU, CH2Cl2, 0 ꢀC, 5 h, then
þ4 ꢀC, 3 days, 23% of 9, 16% of 9a (both from 7); (h) NH3, MeOH, rt, 7 days, 71%.
S
H2N
OBz
RO
OR1
O
O
O
O
The synthesis of 2 is outlined in Scheme 1. The sequence started
with hydrolytic removal of the dioxolane protection in 411 that was
achieved with 4:1 mixture of trifluoroacetic acid and 6 M hydro-
chloric acid at þ4 ꢀC. The resulting unstable aldehyde 5 was not
purified, but was immediately treated with hydroxylamine hydro-
chloride to yield the corresponding oxime 6 as a mixture of the
corresponding E- and Z-isomers. The mixture was not separated
but was further treated with mesyl chloride in pyridine to give the
corresponding nitrile 7 in 66% yield (with respect to reacted
starting compound 4). Exposure of 7 to hydrogen sulfide gas gave
the thioamide 8 (90%). The Hantzsch12 reaction of 8 with ethyl
bromopyruvate afforded the corresponding thiazole 9 (43%), along
with a minor amount of the aromatised product 9a (10%). At this
point we wanted to explore an alternative route to thiazole 9 via the
key thiazoline intermediate 10 that should be accessible from the
nitrile 7 according to an established protocol.10 Thus, compound 7
was allowed to react with cysteine ethyl ester hydrochloride in the
presence of triethylamine at room temperature to afford thiazoline
10 as an inseparable mixture of C-4 epimers. The crude mixture was
not separated but was immediately treated with bromotrichloro-
methane and DBU to give the thiazole 9 in a yield of 23% over the
two steps. Oxidation of 10 not only converted the thiazoline ring to
a thiazole ring but also concomitantly eliminated the 20,30-ester
groups to form the aromatised by-product 9a (16%). It appeared
15a R = Ms, R1 = H
15b R = Ms, R1 = Bz
16 R = R1 = Bz
14a
O
H2N
S
N
OH
RO
OBz
O
O
O
BzO
OMs
17 R = Ms
18 R = Bz
ent-3
Scheme 2. Reagents and conditions: (a) 4:1 TFA–6M HCl, 22 ꢀC, 25 h; (b) NaBH4,
MeOH, 0 ꢀC/rt, 2.5 h, 49% (from 11); (c) KCN, DMSO, 45–49 ꢀC, 76 h, 30% of 14, 3% of
16; (d) Bu4NCN, MeCN, 40 ꢀC, 72 h, 47% of 14, 10% of 15b, 5% of 16; (e) Bu4NCN, BzCN,
MeCN, 40 ꢀC, 76 h, 23% of 14, 12% of 16, 12% of 18.
The sequence commenced from the known dimesylate 11,
which was readily available from glucose monoacetonide over six
steps.11 Hydrolytic removal of the acetal protecting group in 11 gave
the unstable aldehyde 12, which was not purified but was further
treated with sodium borohydride in methanol to afford the

M. Popsavin et al. / Tetrahedron 65 (2009) 7637–7645
7639
corresponding primary alcohol 13 (39% from 11). Treatment of 13
with potassium cyanide in dry DMSO (45–49 ꢀC) unexpectedly gave
a low yield of epoxy-nitrile 14 (30%) as the main reaction product,
along with a minor amount of di-O-benzoyl derivative 16 (3%).14
The major product 14 was most likely formed by a sequential three-
step process that was promoted by a cyanide anion. The first step
of the sequence presumably involved an initial cyanide-catalyzed
4-O-debenzoylation15 of 13 followed by epoxide ring closure to
afford 15a. The benzoyl cyanide thus released subsequently ben-
zoylated16 the primary hydroxyl group in 15a to give the in-
termediate 15b, which was finally converted to product 14 after
nucleophilic displacement of C-5 sulfonyloxy group with the cya-
nide anion. The postulated intermediates 15a and 15b could not be
isolated from the reaction mixture. However, when the reaction of
13 was carried out in the presence of tetrabutylammonium cyanide
(MeCN, 40 ꢀC, 72 h), apart from the epoxy-nitrile 14 that was
obtained in 47% yield and minor amounts of 16 (5%), the in-
termediate 15b was isolated in 10% yield. The side-product 16 was
presumably formed by a competitive two-step sequence that in-
volved demesylation of intermediate 15b promoted by cyanide
followed by concomitant benzoylation of the liberated primary OH
function at C-5 with benzoyl cyanide. This implies that, under these
reaction conditions, both epoxide ring closure and O-benzoylation
steps preceded nucleophilic displacement of the C-6 sulfonyloxy
group. However, when the reaction of 13 was carried out in the
presence of benzoyl cyanide (Bu4NCN, MeCN, 40 ꢀC, 72 h) a messy
reaction mixture was obtained containing at least three products
which were separated with difficulty. A complete conversion of 15b
was observed under these reaction conditions, along with a de-
creased yield of the epoxy-nitrile 14 (23%) as well as an increased
yield of 16 (12%). A minor amount of tribenzoate 18 (12%) was also
formed as a result of successive O-demesylation of 1717 and con-
comitant benzoylation of the liberated primary OH at C-6. This
indicates that under these reaction conditions the removal of the
primary O-mesyl group with cyanide anion occurs even faster with
respect to the competitive epoxide ring closure process.
group in 14 strongly decreases the reactivity of its nitrile function.
In order to avoid the epoxide ring closure process (that obviously
preceded the displacement of mesyloxy group in 13), the triflate
ester 20 was envisaged as a convenient intermediate for the
preparation of analogue 3 (Scheme 3). Compound 20 contains
a much better leaving group at the primary position that would
ensure introduction of the nitrile function under mild reaction
conditions, hopefully without undesirable epoxide ring closure.
BzO
R
BzO
O
O
c
R
BzO
OMs
BzO
OMs
20 R = OTf
21 R = CN
22 R = CSNH2
4 R = 2-dioxol.
5 R = CHO
19 R = CH2OH
a
b
d
e
f
O
O
EtO
EtO
N
N
S
S
BzO
BzO
O
O
BzO
OMs
BzO
OMs
23
24
g
g
O
O
N
H2N
O
H2N
O
4
5
N
S
S
HO
HO
2
5'
4'
2'
3'
1'
6'
Compound 14 proved to be crystalline and its structure was
conclusively established by X-ray analysis (Fig. 2).
O
O
3
25
Scheme 3. Reagents and conditions: (a) 4:1 TFA–6 M HCl, 4 ꢀC, 140 h; (b) NaBH4,
MeOH, 0 ꢀC, 40 min, then rt, 40 min, 64% from 4; (c) Tf2O, Py, CH2Cl2, ꢁ10 ꢀC, 0.5 h,
then rt, 0.5 h; (d) NaCN, DMF, rt, 1.5 h, 73% from 21; (e) H2S, Py, rt, 14 days, 78%;
(f) BrCH2COCO2Et, EtOH, 80 ꢀC, 50 min, 32% of 23, 21% of 24; (g) NH3, MeOH, rt, 8 days,
60% of 3, 65% of 25.
Compound 4 was hydrolysed under the same reaction condi-
tions as described above, and the resulting crude aldehyde 5 was
immediately treated with sodium borohydride in methanol. The
corresponding primary alcohol 19 was thus obtained in 64% overall
yield. Reaction of 19 with triflic anhydride in pyridine and
dichloromethane gave the unstable triflic ester 20 as an oil, which
was used in the next step immediately after its isolation from the
reaction mixture by solvent extraction. Treatment of crude 20 with
NaCN (DMF, rt), or with KCN in the presence of benzo-15-crown-5
ether (MeCN, 0 ꢀC), gave the heptononitrile 21 as the major reaction
product (72–73% from 19). The nitrile 21 was treated with hydrogen
sulfide gas under the conditions similar to those already used for
the preparation of 8. However, the conversion of 21 to 22 required 14
days to be complete, whereby the desired thioamide 22 was obtained
in 78% yield. The Hantzsch reaction of 22 with ethyl bromopyruvate in
ethanol gave the thiazole 23 (32%), accompanied with a minor amount
Figure 2. ORTEP presentation of structure 14.
Unfortunately, reaction of 14 with hydrogen sulfide failed to
produce the corresponding thioamide 14a (Scheme 2). Even after
14 days starting compound 14 remained as a predominant com-
ponent while only traces of thioamide 14a could be detected by TLC
in the reaction mixture. Attempted cyclocondensation of 14 with
cysteine ethyl ester hydrochloride also failed to give the corre-
sponding thiazoline. It appears that the presence of an epoxide
of the C-10 epimer 24 (21%). The
a-anomer 24 was presumably formed
from 23 via a ring opening/ring closure process promoted by HBr,
which was formed as a by-product in the Hantzsch reaction. Although
the acid-catalysed anomerisation of some
osides has been reported,18 this is the first example of such a conver-
sion involving a -arabinofuranosyl-C-nucleoside. Stereochemistry
a-D-ribofuranosyl-C-nucle-
b-D

7640
M. Popsavin et al. / Tetrahedron 65 (2009) 7637–7645
of 23 and 24 was unambiguously resolved by NOE differential 1H
NMR spectroscopy. Designation of the -anomer 23 was based
upon observation of a NOE at H-10 when H-60 was irradiated. This
line, when compared to 1 and DOX, respectively. Compound 2 was
devoid of any cytotoxicity against HT-29 cells, while both homo-C-
nucleosides 3 and 25 exhibited sub-micromolar cytotoxicity against
b
effect was not observed in 24, presumably the
a
-anomer. However,
these malignant cells. The b-homo-C-nucleoside 3 exhibited the
this stereoisomer exhibited a strong NOE between H-10 and H-30,
thus implying a spatial vicinity of these protons. Such an arrange-
most potent antiproliferative activity, being 26- and 15-fold more
active than 1 and DOX, respectively. Compound 25 demonstrated
a similar potency as DOX against HT-29 cells, but it was found to be
over 2-fold more potent with respect to tiazofurin (1) in the same cell
line. The analogues 3 and 25 were found to be somewhat less active
than the parent compound 1 against the breast adenocarcinoma
MCF-7. However, the 20,30-anhydro derivative 2 exhibited a similar
cytotoxicity towards this cell line as tiazofurin itself. Remarkably, all
newly synthesized tiazofurin analogues 2, 3 and 25 were found to be
completely inactive against the normal MRC-5 cells.
ment is only possible if the isomer 24 represents the a-anomer.
Both isomers 23 and 24 upon treatment with saturated ammonia in
methanol gave the expected homo-C-nucleosides 3 and 25 in 60%
and 65% yields, respectively.
2.1. Evaluation of cytotoxic activity
Compounds 2, 3 and 25 were evaluated for their in vitro cyto-
toxicity towards the following human leukemic and solid tumour
cell lines: myelogenous leukaemia K562, promyelocytic leukaemia
HL-60, T-cell leukaemia (Jurkat), Burkitt’s lymphoma (Raji), colon
adenocarcinoma HT-29, estrogen receptor positive breast adeno-
carcinoma MCF-7 cell line, as well as normal foetal lung fibroblasts
(MRC-5). Cytotoxic activity was evaluated by using the standard
MTT assay, after exposure of cells to the tested compounds for 72 h.
Tiazofurin (1) and the commercial antitumour agent doxorubicin
(DOX) were used as reference compounds in this bioassay. The
results are presented in Table 1.
3. Conclusions
In summary, three novel tiazofurin derivatives, 20,30-anhydro-
tiazofurin (2) and the corresponding
b-(3) and a-(25) homo-C-
nucleosides, have been synthesized and evaluated for their in vitro
antitumour activity against a number of human neoplastic cell
lines. Molecule 2 showed the most pronounced cytotoxic activity
against Raji cells, being almost 30-fold more potent than the parent
compound, tiazofurin (1). Compound 3 exhibited even more potent
cytotoxicity towards these cells, being 528-fold more active with
respect to the reference compound 1. The most powerful anti-
tumour activity of compound 25 was recorded in the K562 cell line,
being 38-fold more active than tiazofurin. Moreover, none of the
synthesized analogues showed any significant cytotoxicity towards
the normal foetal lung fibroblasts. Based upon the potent anti-
tumour activities of 2, 3 and 25, as well as upon their non-toxicity
against normal MRC-5 cells, we believe that these tiazofurin
mimics may serve as convenient leads in the synthesis of more
potent and selective antitumour agents derived from the parent
molecule 1. Finally, to the best of our knowledge, compounds 2, 3
and 25 are the first biologically active tiazofurin analogues bearing
a 2,3-anhydro ribofuranosyl moiety, while the analogues 3 and 25
represent the first homo-C-tiazofurin derivatives that demonstrate
antiproliferative activity.
Table 1
In vitro cytotoxicity of 1, 2, 3, 25 and DOX
Compds
IC50, m
Ma
K562
HL-60
Jurkat
Raji
HT-29
MCF-7
MRC-5
Tiazofurin (1)
2
3
25
DOX
1.89
0.64
0.16
0.05
0.25
0.19
0.21
33.69
>100
0.92
0.04
1.64
1.68
>100
0.03
5.28
0.18
0.01
>100
2.98
0.26
>100
0.01
0.12
0.15
1.78
1.91
2.67
10.08
0.20
0.36
>100
>100
>100
0.10
a
IC50 is the concentration of compound required to inhibit the cell growth by 50%
compared to an untreated control. Values are means of three independent experi-
ments done in quadruplicates. Coefficients of variation were <10%.
Remarkably, all three analogues 2, 3 and 25 exhibit sub-micro-
molar cytotoxicity against K562 malignant cells, with IC50 values
ranging from 0.05 to 0.64
mM. The most active compound against
4. Experimental
these cells is the -homo-C-nucleoside 25, being 38-fold more cy-
a
totoxic than tiazofurin, an orphan drug which was approved for
treatment of myelogenous leukaemia. At the same time, this mol-
ecule demonstrated a 5-fold greater cytotoxicity than DOX towards
K562 cell line. Compounds 2 and 3 also efficiently inhibited
the growth of K562 cells, with respective IC50 values being 3- and
12-fold lower than those observed for the reference compound 1.
The most active compound against HL-60 cells was 20,30-anhydro-
tiazofurin (2) that exhibited the same antiproliferative activity as
tiazofurin (1). However, this molecule was found to be over 4-fold
4.1. General methods
Melting points were determined on a Bu¨chi 510 apparatus and
were not corrected. Optical rotations were measured on P 3002
(Kru¨ss) and Polamat A (Carl–Zeiss) polarimeters at room temper-
ature. IR spectra were recorded with Specord 75 (Carl–Zeiss) and
Nexus 670 (Thermo Nicolet, DTGS-detector) IR spectrophotome-
ters. NMR spectra were recorded on a Bruker AC 250 E instrument
and the chemical shifts (
d-scale) are expressed in ppm values
more active than DOX in the same cell line. The
b
-homo-C-nucle-
downfield from tetramethylsilane. Chemical ionization low reso-
lution mass spectra were recorded on Finnigan-MAT 8230 spec-
trometer with isobutane as a reagent gas. High-resolution mass
spectra (ESI) were taken on a Micromass LCT KA111 spectrometer.
TLC was performed on DC Alufolien Kieselgel 60 F254 (E. Merck).
Column chromatography was performed on Kieselgel 60
(<0.063 mm, E. Merck). Flash column chromatography was per-
formed using Kieselgel 60 (0.040–0.063, E. Merck). Self-made
preparative TLC plates were prepared using Kieselgel 60 G
(E. Merck) with Fluorescent Indicator F254 as additive. The corre-
sponding bands were scraped and eluted with the respective sol-
vent through short column chromatography. All organic extracts
were dried with anhydrous Na2SO4 (if not stated otherwise). Or-
ganic solutions were concentrated in a rotary evaporator under
diminished pressure at a bath temperature below 35 ꢀC.
oside 3 showed a moderate cytotoxicity against the HL-60 cells,
while the analogue 25 was found to be completely inactive against
this cell line. Tiazofurin remains the most potent compound to-
wards the Jurkat T cells and exhibited almost the same cytotoxicity
as the commercial antitumour agent doxorubicin (DOX). The ana-
logues 2 and 3, showed similar and potent antitumour activities in
this cell line, but they were over 40-fold less potent than the ref-
erence compound 1. The most potent antiproliferative activity of
compounds 2 and 3 was recorded towards Raji malignant cells.
Remarkably, the
b-homo-C-nucleoside 3 exhibited much more
pronounced cytotoxicity against these cells, being approximately
530- and 300-fold more active with respect to both reference
compounds 1 and DOX, respectively. At the same time, compound 2
demonstrated a 30- and 16-fold greater cytotoxicity in the same cell

M. Popsavin et al. / Tetrahedron 65 (2009) 7637–7645
7641
4.1.1. 2,5-Anhydro-4,6-di-O-benzoyl-3-O-methanesulfonyl-
D
-
d 38.1 (OMs), 63.8 (C-6), 78.2 (C-4), 83.5 (C-3), 84.9 (C-5), 86.8 (C-2),
glucononitrile (7)
128.2,128.4,128.6,128.9, 129.3,129.9,133.4 and 134.0 (2ꢂPh),165.0
and 167.0 (2ꢂPhCO), 197.7 (CSNH2). No extraneous peaks viewed by
NMR. LRMS (CI): m/z 480 (MHþ).
A solution of 4 (1.230 g, 2.50 mmol) in a mixture of TFA (6 mL)
and 6 M HCl (1.5 mL) was kept at þ4 ꢀC for 120 h and then poured
into satd aq NaHCO3 (20 mL). The aqueous solution was rendered
alkaline with solid NaHCO3 (to pH 8–9) and extracted with CH2Cl2
(4ꢂ20 mL). The combined extracts were dried (1:1 Na2SO4/Na2CO3)
and evaporated to give crude 5 (1.287 g) as a yellow oil. The crude
aldehyde 5 was immediately dissolved in a mixture of dry EtOH
(13.5 mL) and CH2Cl2 (1.2 mL) and treated with NH2OH$HCl
(0.631 g, 9.08 mmol) and anhydrous NaOAc (0.473 g, 5.77 mmol)
while stirring at room temperature for 24 h. The mixture was
evaporated, the residue was suspended in water (15 mL) and
extracted with CH2Cl2 (4ꢂ20 mL). The extract was dried (1:1
Na2SO4/Na2CO3) and evaporated to afford crude oxime 6 (1.069 g)
4.1.3. Ethyl 2-(3,5-di-O-benzoyl-2-O-methanesulfonyl-b-D-
arabinofuranosyl)thiazole-4-carboxylate (9)
Procedure A. A solution of 8 (1.653 g, 3.45 mmol) and ethyl
bromopyruvate (0.49 mL, 3.92 mmol) in absolute EtOH (24 mL) was
stirred under reflux for 50 min. The solvent was evaporated in
vacuum, and the residue was chromatographed through a column
of silica gel (100 g, 17:3/7:3 toluene/EtOAc). The aromatised side-
product 9a (0.123 g, 10%) was isolated first as a colourless syrup,
Rf¼0.64 (17:3 toluene/EtOAc). 1H NMR (CDCl3):
d 1.42 (t, 3H,
J¼7.0 Hz, CO2CH2CH3), 4.43 (q, 2H, J¼7 Hz, CO2CH2CH3), 5.36 (s, 2H,
as a mixture of E- and Z-isomers. 1H NMR (CDCl3):
d 3.08 and 3.12
H-50), 6.64 and 7.16 (2ꢂd, 2H, J2 ,3 ¼3.3 Hz, H-2 and H-3 ), 7.37–8.10
0
0
0
0
(2ꢂs, 6H, 2ꢂOMs, E/Z-isomers), 4.39 and 4.47 (2ꢂm, 2ꢂH-5, E/Z-
isomers), 4.59–4.78 (m, 2ꢂH-6, E/Z-isomers), 4.83 (dd, J1,2¼6.7 Hz,
J2,3¼3.7 Hz, H-2, E-isomer), 5.27 (t, J¼3.4 Hz, H-2, Z-isomer),
5.32 (d, H-3, E-isomer), 5.59 and 5.56 (2ꢂd, H-4, E/Z-isomers), 5.61
(d, H-3, Z-isomer), 7.00 (d, H-1, Z-isomer), 7.55 (d, H-1, E-isomer),
7.35–8.20 (m, 2ꢂPh, E/Z-isomers), 8.60 and 9.11 (2ꢂbr s, OH, E/Z-
(m, 5H, Ph), 8.13 (s, 1H, H-5). 13C NMR (CDCl3):
d 14.2 (CO2CH2CH3),
58.2 (C-50), 61.5 (CO2CH2CH3), 111.1 and 113.3 (C-20 and C-30), 126.3
(C-5), 128.3, 128.4, 129.8 and 133.2 (Ph), 147.9 (C-4), 151.3 and 158.2
(C-10 and C-40), 161.1 (C-2), 166.0 (PhCO), 170.1 (CO2Et). No extra-
neous peaks viewed by NMR. The major product 9 (0.844 g, 43%)
23
was isolated as a pale yellow oil, homogeneous by TLC, [
1.37, MeOH); Rf¼0.47 (17:3 toluene/EtOAc).
a]
þ3.4 (c
D
isomers). 13C NMR (CDCl3):
d
38.5 and 38.6 (2ꢂOMs, E/Z-isomers),
63.5 (C-6, E/Z-isomers), 76.0 (C-2, Z-isomer), 78.2 (C-2, E-isomer),
79.1 and 79.4 (C-4, E/Z-isomers), 81.7 and 81.8 (C-5, E/Z-isomers),
82.9 (C-3, Z-isomer), 83.5 (C-3, E-isomer), 128.3, 128.4, 128.56,
128.61, 129.4, 129.5, 129.7, 129.8, 129.9, 130.0, 133.2, 133.3, 133.9,
140.0 (2ꢂPh, E/Z-isomers), 145.8 (C-1, E-isomer), 147.4 (C-1, Z-iso-
mer), 165.3, 165.4, 166.3 (2ꢂPhCO, E/Z-isomers). To a cooled
(ꢁ15 ꢀC) and stirred solution of crude 6 in anhydrous pyridine
(7.4 mL) was added dropwise during 30 min a cold solution
(ꢁ15 ꢀC) of MsCl (1.61 mL, 20.77 mmol) in dry pyridine (4.4 mL).
The mixture was stirred at ꢁ15 ꢀC for 0.5 h and then at room
temperature for the next 2 h. The mixture was poured into ice and
6 M HCl (pHz2), and the resulting emulsion was extracted with
CH2Cl2 (4ꢂ20 mL). The combined extracts were washed with water
(20 mL), satd aq NaHCO3 (20 mL) and again with water (20 mL). The
extract was dried (1:1 Na2SO4/Na2CO3) and evaporated, and the
residue (0.984 g) was purified by flash column chromatography
Procedure B. To a stirred solution of 7 (0.591 g, 1.33 mmol) in dry
MeOH (20 mL) was added L-cysteine ethyl ester hydrochloride
(0.371 g, 2 mmol) followed by Et3N (0.28 mL, 2.0 mmol) at room
temperature. The reaction mixture was stirred for 2 h and evapo-
rated. The residue was dissolved in CH2Cl2 (75 mL) and washed
with water (30 mL), satd NaHCO3 solution (30 mL), and brine
(30 mL). The organic layer was dried, filtered and evaporated to
give crude 10 (0.805 g) as a colourless foam. To a stirred solution of
crude 10 (0.805 g, 1.39 mmol) in anhydrous CH2Cl2 was added DBU
(0.42 mL, 2.78 mmol). The solution was cooled to 0 ꢀC and BrCCl3
(0.16 mL, 1.67 mmol) was added. The reaction mixture was stirred
for 5 h at 0 ꢀC and then stored at þ4 ꢀC for 3 days. The mixture was
evaporated and the residue was purified by preparative TLC (4:1
toluene/EtOAc, 2 successive developments, eluted with EtOAc) to
give pure by-product 9a (0.076 g, 16%) and slightly impure thiazole
9. Fractions containing 9 were combined and re-chromatographed
on preparative TLC plates (7:3 cyclohexane/Me2CO, 3 successive
(17:3 toluene/EtOAc). 7 (0.607 g, 66% based on reacted 4) was
23
obtained as a colourless oil homogeneous by TLC, [
a
]
ꢁ13.6 (c 1.13,
developments, eluted with EtOAc) to afford 9 (0.177 g, 23%) as
D
23
CHCl3); Rf¼0.45 (17:3 toluene/EtOAc). 1H NMR (CDCl3):
d
3.21 (s, 3H,
a pale yellow oil homogeneous by TLC, [
a]
þ3.4 (c 1.37, MeOH);
D
OMs), 4.51 (ddd, 1H, J5,6a¼5.0 Hz, J5,6b¼4.6 Hz, J4,5¼5.9 Hz, H-5),
4.66 (dd, 1H, J6a,6b¼12.2 Hz, J5,6a¼5.0 Hz, H-6a), 4.74 (dd, 1H,
J6a,6b¼12.2 Hz, J5,6b¼4.6 Hz, H-6b), 5.08 (d, 1H, J2,3¼4.7 Hz, H-2),
5.51 (dd, 1H, J3,4¼2.4 Hz, J2,3¼4.7 Hz, H-3), 5.69 (dd, 1H, J3,4¼2.4 Hz,
Rf¼0.47 (17:3 toluene/EtOAc). IR (neat): nmax 1723 (C]O), 1368 (as.
SO2), 1179 (sym. SO2). 1H NMR (CDCl3):
1.37 (t, 3H, CH3CH2), 2.82
(s, 3H, OMs), 4.39 (q, 2H, CH3CH2), 4.60 (td, 1H, J3 ,4 ¼2.3 Hz,
d
0
0
0
0
0
0
0
0
0
J4 ,5a ¼4.9 Hz, J4 ,5b ¼4.8 Hz, H-4 ), 4.74 (dd, 1H, J5a ,5b ¼11.9 Hz,
J4,5¼5.9 Hz, H-4), 7.42–8.20 (m, 10H, 2ꢂPh). 13C NMR (CDCl3):
d
39.0
J4 ,5a ¼4.9 Hz, H-5a ), 4.83 (dd, 1H, J5a ,5b ¼11.9 Hz, J4 ,5b ¼4.8 Hz, H-
0
0
0
0
0
0
0
0
0
5b0), 5.58 (d, 1H, J1 ,2 ¼3.4 Hz, H-2 ), 5.70 (d, 1H, J3 ,4 ¼2.3 Hz, H-3 ),
0
0
0
0
(OMs), 62.9 (C-6), 69.3 (C-2), 77.4 (C-4), 79.7 (C-3), 82.4 (C-5), 113.6
(CN), 127.9, 128.4, 128.9, 129.3, 129.9, 133.4, 134.2 (2ꢂPh), 165.1 and
166.0 (2ꢂPhCO). No extraneous peaks viewed by NMR. LRMS (CI):
m/z 446 (MHþ). A minor amount of unreacted starting compound 4
(0.215 g, 17%) was recovered.
0
0
0
5.81 (d, 1H, J1 ,2 ¼3.4 Hz, H-1 ), 7.38–8.18 (m, 10H, 2ꢂPh), 8.23 (s, 1H,
H-5). 13C NMR (CDCl3):
d 14.2 (CH3CH2), 38.0 (OMs), 61.5 (CH3CH2),
63.2 (C-50), 80.3 (C-30), 82.7 (C-20), 82.9 (C-40), 128.6 (C-5), 128.28,
128.34, 129.3, 129.7, 129.8, 130.0, 133.2, and 133.4 (2ꢂPh), 146.8 (C-
4), 160.9 (C-2), 165.1 and 166.2 (2ꢂPhCO), 171.1 (CO2Et). No extra-
neous peaks viewed by NMR. LRMS (CI): m/z 576 (MHþ).
4.1.2. 2,5-Anhydro-4,6-di-O-benzoyl-3-O-methanesulfonyl-
D-gluconothioamide (8)
Throughout a solution of 7 (0.591 g, 1.33 mmol) in anhydrous
4.1.4. 2-(2,3-Anhydro-b-D-ribofuranosyl)thiazole-4-
pyridine (3 mL) was passed H2S gas for 4 h at room temperature.
The mixture was evaporated and the residue was purified on
a column of silica gel (33 g, 4:1 toluene/EtOAc). 8 (0.572 g, 90%) was
carboxamide (2)
A solution of 9 (0.153 g, 0.27 mmol) in saturated methanolic
ammonia (8 mL) was kept at room temperature for 7 days, and then
evaporated. The residue was purified by preparative TLC (9:1
CH2Cl2/MeOH, eluted with 1:1 iPrOH/EtOAc) to afford pure 2
23
obtained as a colourless oil homogeneous by TLC, [
a]
þ29.4 (c 1.11,
D
CHCl3). Rf¼0.6 (7:3 toluene/EtOAc). 1H NMR (CDCl3):
d 3.08 (s, 3H,
OMs), 4.59 (ddd, 1H, J4,5¼1.4 Hz, J5,6a¼3.2 Hz, J5,6b¼7.2 Hz, H-5),
4.67 (dd, 1H, J6a,6b¼11.9 Hz, J5,6a¼3.2 Hz, H-6a), 4.96 (dd, 1H,
J6a,6b¼11.9 Hz, J5,6b¼7.2 Hz, H-6b), 5.28 (d, 1H, J2,3¼3.6 Hz, H-2),
5.51 (d, 1H, J2,3¼3.6 Hz, H-3), 5.58 (d, 1H, J4,5¼1.4 Hz, H-4), 7.40–8.14
(m, 10H, 2ꢂPh), 7.99 and 8.59 (2ꢂbr s, 2H, NH2). 13C NMR (CDCl3):
(0.046 g, 71%) as a white solid. Recrystallization from MeOH gave an
23
analytical sample 16 as colourless crystals, mp 120–121 ꢀC, [
a]
D
þ32.8 (c 1.18, MeOH), Rf¼0.35 (9:1 CH2Cl2/MeOH). 1H NMR
0
0
0
0
0
(methanol-d4):
d
3.36 (dd, 1H, J5a ,5b ¼11.4 Hz, J4 ,5a ¼6.5 Hz, H-5a ),
0
0
0
0
0
3.45 (dd, 1H, J5a ,5b ¼11.4 Hz, J4 ,5b ¼5.5 Hz, H-5b ), 3.75 (d, 1H,

7642
M. Popsavin et al. / Tetrahedron 65 (2009) 7637–7645
0
0
0
0
0
0
0
0
J2 ,3 ¼2.8 Hz, H-3 ), 4.05 (dd, 01H, J4 ,5a ¼6.5 Hz, J4 ,5b ¼5.5 Hz, H-4 ),
J2b,3¼6.3 Hz, H-3), 4.48 (dd, 1H, J6,7a¼4.8 Hz, J6,7b¼3.6 Hz, H-6), 4.58
(dd, 1H, J7a,7b¼10.8 Hz, J6,7b¼3.6 Hz, H-7b), 7.44–8.08 (m, 5H, Ph).
0
0
0
4.11 (d, 1H, J2 ,3 ¼2.8 Hz, H-2 ), 5.10 (s, 1H, H-1 ), 8.21 (s, 1H, H-5).
NOE contact: H-10 and H-40. 13C NMR (methanol-d4):
d
59.9 (C-30),
13C NMR (CDCl3):
d 21.8 (C-2), 58.4 and 59.4 (C-4, C-5), 64.3 (C-7),
61.0 (C-20), 63.3 (C-50), 79.0 (C-10), 82.1 (C-40), 126.1 (C-5), 151.2 (C-
4), 165.5 (C-2), 172.1 (CONH2). LRMS (CI): m/z 243 (MHþ). Anal.
Found: C, 43.00; H, 4.34; N, 11.42; S, 12.81. Calcd for
C9H10N2O4Sꢂ0.5H2O: C, 43.02; H, 4.41; N, 11.15; S, 12.76.
74.1 (C-3), 77.5 (C-6), 116.1 (CN), 128.7, 129.2, 129.5 and 133.6 (Ph),
165.9 (PhCO). HRMS (ESI): Found: 282.0735 (MNaþ). Calcd for
C14H13NO4Na: 282.0742.
20
Compound 15b: mp 96 ꢀC (CH2Cl2/hexane), [
a
]
þ15.8 (c 1.17,
D
CHCl3); Rf¼0.53 (10:1 CH2Cl2/EtOAc). IR (KBr): nmax 1720 (C]O),
1357 (as. SO2), 1176 (sym. SO2). 1H NMR (CDCl3):
3.05 (s, 3H, OMs),
3.93 (s, 2H, H-3 and H-4), 4.31–4.62 (m, 6H, 2ꢂH-1, 2ꢂH-6, H-2 and
H-5), 7.42–8.18 (m, 5H, Ph). 13C NMR (CDCl3):
37.5 (OMs), 58.2 and
4.1.5. 2,5-Anhydro-4-O-benzoyl-3,6-di-O-methanesulfonyl-
d
D-glucitol (13)
A solution of 11 (3.344 g, 7.18 mmol) in a mixture of TFA (32 mL)
d
and 6 M HCl (8 mL) was kept at 22 ꢀC for 25 h. The workup as de-
scribed above (preparation of 5) gave crude 12 (3.032 g) as a brown
oil. To a stirred and cooled (0 ꢀC) solution of 12 in MeOH (15 mL),
was added NaBH4 (0.360 g, 9.52 mmol) in portions over 0.5 h. The
cooling bath was removed and the stirring was continued at room
temperature for 2.5 h. The mixture was poured into saturated aq
NaCl (20 mL) and the resulting emulsion was extracted with CH2Cl2
(4ꢂ25 mL). The combined extracts were washed with satd aq NaCl,
dried and evaporated. The remaining crude mixture was purified by
preparative TLC (87 plates, 7:3 toluene/EtOAc, eluted with 1:1
58.4 (C-3 and C-4), 64.1 (C-1), 68.1 (C-6), 128.6, 129.3, 129.6 and
133.4 (Ph), 166.1 (PhCO). HRMS (ESI): Found: 329.0682 (MHþ).
Calcd for C14H17O7S: 329.0690.
Compound 16: Rf¼0.84 (2:1 CH2Cl2/EtOAc). IR (neat): nmax 1721
(C]O). 1H NMR (CDCl3):
d 3.96 (s, 2H, H-3 and H-4), 4.34–4.55 (m,
6H, H-1, H-6, H-2 and H-5), 7.37–8.11 (m,10H, Ph). 13C NMR (CDCl3):
58.5 (C-3 and C-4), 64.1 (C-1 and C-6), 76.9 (C-2 and C-5), 128.5,
d
129.4, 129.7 and 133.4 (Ph), 166.1 (PhCO). HRMS (ESI): Found:
355.1179 (MHþ). Calcd for C20H19O6: 355.1176.
20
Compound 18: [
a
]
þ26.1 (c 0.27, CHCl3), Rf¼0.87 (10:1 CH2Cl2/
D
iPrOH/EtOAc) to give pure 13 (1.484 g, 49% from 11) that was iso-
EtOAc). IR (neat): nmax 1720 (C]O), 1367 (as. SO2), 1178 (sym. SO2).
lated as a colourless oil, [
a
]
D
þ6.6 (c 1.88, CHCl3), Rf¼0.6 (2:1
1H NMR (CDCl3):
d
3.18 (s, 3H, Ms), 4.48 (m, 1H, J4,5¼3.2 Hz,
23
CH2Cl2/EtOAc). 1H NMR (CDCl3):
d
2.85 (br s, 1H, exchangeable with
J5,6¼4.3 Hz, J5,6¼4.9 Hz, H-5), 4.58 (m, 1H, J2,3¼3.4 Hz, J1,2¼6.1 Hz,
H-2), 4.62–4.75 (m, 4H, H-1 and H-6), 5.37 (d, 1H, J2,3¼3.4 Hz, H-3),
5.57 (d, 1H, J4,5¼3.2 Hz, H-4), 7.30–8.21 (m, 15H, Ph). 13C NMR
D2O, OH), 3.09 and 3.24 (2ꢂs, 3H each, 2ꢂOMs), 3.93 (d, 2H,
J1,2¼6.0 Hz, 2ꢂH-1), 4.33 (m, 2H, H-2 and H-5), 4.49 (dd, 1H,
J6a,6b¼11.4 Hz, J5,6a¼4.5 Hz, H-6a), 4.55 (dd, 1H, J6a,6b¼11.4 Hz,
J5,6b¼4.2 Hz, H-6b), 5.27 (dd, 1H, J3,4¼0.8 Hz, J2,3¼3.4 Hz, H-3), 5.45
(dd, 1H, J3,4¼0.8 Hz, J4,5¼3.2 Hz, H-4), 7.44–8.11 (m, 5H, Ph). 13C
(CDCl3):
d 38.7 (OMs), 61.5 and 63.5 (C-1 and C-6), 78.3, 79.1, 81.6
and 82.4 (C-2, C-4, C-5 and C-3), 128.37, 128.43, 128.6, 129.56,
129.64, 129.67, 129.79, 129.84, 133.2, 133.3, 134.0 (Ph), 165.5, 166.1
and 166.2 (3ꢂPhCO). HRMS (ESI): Found: 555.1319 (MHþ). Calcd for
C28H27O10S: 555.1319.
NMR (CDCl3):
d
37.5 and 38.3 (2ꢂOMs), 59.4 (C-1), 67.9 (C-6), 78.3
(C-4), 80.87 and 80.91 (C-2, C-5), 81.7 (C-3), 128.2, 128.6, 129.8 and
134.0 (Ph), 165.5 (PhCO). LRMS (CI): m/z 425 (MHþ). Anal. Found: C,
42.03; H, 4.87; S, 15.39. Calcd for C15H20O10S2: C, 42.45; H, 4.75; S,
15.11.
4.1.7. 2,5-Anhydro-4,6-di-O-benzoyl-3-O-methanesulfonyl-
D-glucitol (19)
A solution of 4 (5.6 g, 11.38 mmol) in a mixture of TFA (27.3 mL)
4.1.6. 3,6:4,5-Dianhydro-7-O-benzoyl-2-deoxy-
heptononitrile (14)
L
-alo-
and 6 M HCl (6.8 mL) was kept at þ4 ꢀC for 140 h. The workup as
described above (Section 4.1.1.) gave crude 5 (5.857 g) as a yellow
oil. The crude aldehyde 5 (5.857 g, 13.07 mmol) was immediately
dissolved in MeOH (22 mL) cooled to 0 ꢀC and treated with NaBH4
(0.49 g, 12.95 mmol) for 40 min. The cooling bath was removed and
the stirring was continued at room temperature for 40 min, then
quenched with saturated NH4Cl (40 mL), and extracted with EtOAc
(4ꢂ25 mL). The combined organic phases were dried and evapo-
rated, and the residue was purified by flash column chromatogra-
phy (7:3 toluene/EtOAc). The unchanged starting compound 4
Procedure A. A suspension composed of 13 (0.319 g, 0.75 mmol)
and KCN (0.151 g, 2.32 mmol) in DMSO (8 mL) was stirred at 45–
49 ꢀC for 76 h. The solvent was removed and the residue was
extracted with CH2Cl2. The organic solution was evaporated and the
oily residue was purified by preparative TLC (7 plates, 10:1 CH2Cl2/
EtOAc, eluted with 1:1 CH2Cl2/EtOAc) to furnish 14 (0.058 g, 30%) as
a colourless solid. Crystallization from a mixture of CHCl3/hexane
gave an analytical sample of 14. A minor amount of 16 (0.007 g; 3%)
was also isolated as colourless oil.
Procedure B. A solution of 13 (0.208 g; 0.49 mmol) and Bu4NCN
(0.254 g; 0.94 mmol) in dry MeCN (8.4 mL) was stirred at 40 ꢀC for
72 h. The mixture was evaporated and purified by preparative TLC
(4 plates, 10:1 CH2Cl2/EtOAc, eluted with 1:1 CH2Cl2/EtOAc) to give
14 (0.0597 g; 47%). A minor amount of 15b (0.016 g; 10%) was iso-
lated as a colourless solid. A minor amount of 16 (0.009 g; 5%) was
also isolated as colourless oil.
(1.426 g, 25%) was first eluted, followed by pure 19 (2.440 g, 64% on
23
the basis of the recovered 4) isolated as a colourless oil, [
a
]
þ20.0
D
(c 1.3, CHCl3), Rf¼0.61 (2:1 CH2Cl2/EtOAc). 1H NMR (CDCl3):
d 2.94
(br s, 1H, exchangeable with D2O, OH), 3.15 (s, 3H, OMs), 3.93 (d, 2H,
J1,2¼6.0 Hz, 2ꢂH-1), 4.30 (td, 1H, J1,2¼6.0 Hz, J2,3¼3.6 Hz, H-2), 4.40
(m, 1H, H-5), 4.59 and 4.64 (2ꢂdd, 2H, Jgem¼11.9 Hz, J5,6¼4.6 Hz,
2ꢂH-6), 5.25 (d, 1H, J3,4¼1.0 Hz, H-3), 5.49 (dd, 1H, J3,4¼1.0 Hz,
J4,5¼3.7 Hz, H-4), 7.36–8.10 (m, 10H, 2ꢂPh). 13C NMR (CDCl3):
d 38.2
Procedure C. A solution of 13 (0.202 g; 0.48 mmol), Bu4NCN
(0.254 g; 0.94 mmol) and BzCN (0.0837 g; 0.64 mmol) in dry MeCN
(8.2 mL) was stirred at 40 ꢀC for 76 h. The mixture was evaporated
and purified by preparative TLC as described above (Section B) to
give pure 14 (0.028 g; 23%) as colourless crystals. A minor amounts
of 16 (0.020 g; 12%) and 18 (0.032 g; 12%) were isolated as colour-
(CH3SO2), 59.5 (C-1), 63.6 (C-6), 79.1 (C-4), 80.8 (C-2), 80.9 (C-5),
82.6 (C-3), 128.3, 129.3, 129.48, 129.54, 129.6, 129.7, 133.2, 133.8
(2ꢂPh), 165.5 and 166.2 (2ꢂPhCO). LRMS (CI): m/z 451 (MHþ). Anal.
Found: C, 54.60; H, 5.03; S, 7.00. Calcd for C21H22O9Sꢂ0.5H2O: C,
54.89; H, 5.05; S, 6.98.
less oils.
4.1.8. 3,6-Anhydro-5,7-di-O-benzoyl-2-deoxy-4-O-
methanesulfonyl-D-gluco-heptononitrile (21)
20
Compound 14: mp 144–148 ꢀC (CHCl3/hexane), [
a]
þ19.0 (c
D
0.76, CHCl3), Rf¼0.69 (10:1 CH2Cl2/EtOAc). IR (KBr): nmax 2249 (CN),
Procedure A. To a cooled (ꢁ10 ꢀC) and stirred solution of 19
(1.245 g, 2.77 mmol) in dry pyridine (0.96 mL, 11.92 mmol) and
CH2Cl2 (25 mL), was added a cooled (ꢁ10 ꢀC) solution of Tf2O
(0.71 mL, 3.58 mmol) in dry CH2Cl2 (9.5 mL). The mixture was first
stirred at ꢁ10 ꢀC for 0.5 h, then at room temperature for 0.5 h, and
1718 (C]O). 1H NMR (CDCl3):
d
2.62 (dd, 1H, J2a,2b¼16.8 Hz,
J2a,3¼7.1 Hz, H-2a), 2.70 (dd, 1H, J2a,2b¼16.8 Hz, J2b,3¼6.3 Hz, H-2b),
3.89 and 3.98 (2ꢂd, 2H, J4,5¼2.7 Hz, H-4, H-5), 4.41 (dd, 1H,
J7a,7b¼10.8 Hz, J6,7a¼4.8 Hz, H-7a), 4.42 (dd, 1H, J2a,3¼7.1 Hz,

M. Popsavin et al. / Tetrahedron 65 (2009) 7637–7645
7643
then diluted with CH2Cl2 (50 mL). The organic solution was washed
successively with 10% aq HCl (50 mL), and water (50 mL). The or-
ganic phase was dried and evaporated to give crude 20 (1.726 g) as
an unstable pale yellow syrup that was used in the next synthetic
50 min. After workup as described above (Section 4.1.3A), the
crude mixture was first purified by flash column chromatography
(4:1 toluene/EtOAc), and then by preparative TLC (7:3 toluene/
EtOAc, 3 successive developments, eluted with EtOAc) to afford
pure 23 (0.186 g, 32%) as a colourless syrup, and pure 24 (0.123 g,
step immediately after its brief isolation. 1H NMR (CDCl3):
d 3.18 (s,
3H, OMs), 4.51 (m, 1H, H-5), 4.57 (m, 1H, H-2), 4.63 (m, 2H,
Jgem¼11.6 Hz, 2ꢂH-6), 4.75 (dd, 1H, J1a,1b¼10.9 Hz, J1a,2¼4.1 Hz, H-
1a), 4.83 (dd, 1H, J1a,1b¼10.9 Hz, J1b,2¼6.7 Hz, H-1b), 5.34 (dd, 1H,
J2,3¼3.6 Hz, J3,4¼1.0 Hz, H-3), 5.54 (dd, 1H, J3,4¼1.0 Hz, J4,5¼3.7 Hz,
21%) as a colourless oil.
23
Compound 23: [
a
]
ꢁ3.0 (c 1.39, CHCl3), Rf¼0.55 (7:3 toluene/
D
EtOAc, 2ꢂdeveloped). 1H NMR (CDCl3):
d
1.37 (t, 3H, J¼7.3 Hz,
CH3CH2), 3.20 (s, 3H, OMs), 03.48 and 3.58 (2ꢂdd, 2H, Jgem¼15.4 Hz,
H-4), 7.36–8.15 (m, 10H, 2ꢂPh). 13C NMR (CDCl3):
d
38.3 (OMs), 63.1
J1 ,2 ¼8.1 and 4.8 Hz, 2ꢂH-1 ), 4.39 (m, 3H, CH3CH2 and H-50), 4.63
0
0
0
0
0
0
0
0
(C-6), 72.9 (C-1), 77.4 (C-2), 78.6 (C-4), 81.4 (C-5), 81.6 (C-3),118.4 (q,
JC,F¼319.8 Hz, CF3), 128.4, 128.5, 129.2, 129.3, 129.4, 129.7, 133.2 and
134.0 (2ꢂPh), 165.4 and 166.0 (2ꢂPhCO). To a solution of crude 20
(1.779 g, 3.06 mmol) in DMF (27.5 mL) was added NaCN (0.374 g,
7.64 mmol) and the resulting suspension was stirred at room tem-
perature for 1.5 h. The mixture was diluted with water (50 mL) and
extracted with a 1:1 mixture of benzene and hexane (4ꢂ60 mL). The
combined extract was washed with water (1ꢂ50 mL), dried and
(d, 2H, J5 ,6 ¼4.7 Hz, H-6 ), 4.71 (m, 1H, J2 ,3 ¼3.4 Hz, H-2 ), 5.22 (d,
1H, H-30), 5.54 (d,1H, H-40), 7.40–8.17 (m,10H, 2ꢂPh), 8.07 (s,1H, H-
5). NOE contacts: CH3SO2 and H-40, CH3SO2 and CH2CH3, H-60 and
H-40, H-60 and H-10. 13C NMR (CDCl3):
d
14.2 (CH3CH2), 32.9 (C-10),
38.6 (OMs), 61.3 (CH3CH2), 63.4 (C-60), 79.3 (C-40), 79.4 (C-20), 81.4
(C-50), 83.5 (C-30), 127.7 (C-5), 128.3, 128.4, 128.5, 129.5, 129.7, 129.8,
133.1 and 133.8 (2ꢂPh), 146.9 (C-4), 161.1 (C-2), 165.4, 166.1 and
166.2 (2ꢂPhCO and CO2Et). LRMS (CI): m/z 590 (MHþ). Anal. Found:
C, 55.04; H, 4.34; N, 2.21; S, 10.54. Calcd for C27H27NO10S2: C, 55.00;
evaporated. Flash column chromatography (9:1 toluene/EtOAc) of
23
the residue gave 21 (0.957 g, 73% from 19) as a colourless oil, [
a
]
H, 4.62; N, 2.38; S, 10.88.
D
23
þ19.6 (c 2.4, CHCl3), Rf¼0.71 (9:1 CH2Cl2/EtOAc).
Compound 24: [
a]
ꢁ5.8 (c 1.6, CHCl3), Rf¼0.63 (7:3 toluene/
D
Procedure B. To a suspension of crude 20 (0.541 g, 0.93 mmol) in
dry MeCN (2 mL) was added KCN (0.058 g, 0.89 mmol) and a solu-
tion of benzo-15-crown-5 (0.727 g, 2.71 mmol) in dry MeCN
(10 mL). The mixture was stirred at 0 ꢀC for 1 h and then evapo-
rated. The residue was dissolved in CH2Cl2 (25 mL) and washed
with satd aq NaCl (2ꢂ10 mL). The organic solution was separated,
dried and evaporated. Chromatographic purification of the residue
EtOAc, 2ꢂdeveloped). 1H NMR (CDCl3):
d 1.37 (t, 3H, CH3CH2), 3.15
0
0
(s, 3H, OMs), 3.49 and 3.62 (2ꢂdd, 2H, J1 ,2 ¼7.7 and 5.2 Hz,
Jgem¼15.3 Hz, 2ꢂH-10), 4.370 (q, 2H, CH3CH2), 4.51–4.73 (m, 3H,
0
0
0
0
0
0
J4 ,5 ¼2.4 Hz, 2ꢂH-6 and H-5 ), 4.79 (m, 1H, J20,3 ¼3.9 Hz, H-2 ), 5.28
0
0
0
(dd, 1H, J3 ,4 ¼2.4 Hz, H-3 ), 5.63 (t, 1H, H-4 ), 7.40–8.12 (m, 10H,
2ꢂPh), 8.09 (s, 1H, H-5). NOE contact: H-30 and H-10. 13C NMR
(CDCl3):
d
14.2 (CH3CH2), 35.6 (C-10), 38.4 (OMs), 61.3 (CH3CH2),
by preparative TLC (9:1 CH2Cl2/EtOAc, eluted with 1:1 CH2Cl2/
63.7 (C-60), 79.4 (C-40), 81.1 (C-50), 81.3 (C-20), 84.7 (C-30), 128.1 (C-
5), 128.4, 128.48, 128.54, 129.4, 129.7, 129.8, 133.2 and 133.8 (2ꢂPh),
146.8 (C-4), 161.0 (C-2), 165.5, 165.6 and 166.1 (2ꢂPhCO and CO2Et).
LRMS (CI): m/z 590 (MHþ). Anal. Found: C, 55.14; H, 4.42; N, 2.19; S,
11.17. Calcd for C27H27NO10S2: C, 55.00; H, 4.62; N, 2.38; S, 10.88.
23
EtOAc) gave 21 (0.315 g, 74% from 19) as a colourless oil, [
a
]
þ19.6
D
(c 2.4, CHCl3), Rf¼0.71 (9:1 CH2Cl2/EtOAc). IR (neat): nmax 2260 (CN),
1726.67 (C]O), 1366.67 (as. SO2), 1186.67 (sym. SO2). 1H NMR
(CDCl3):
d
2.83 (dd, 1H, J1a,2¼6.0 Hz, J1a,1b¼17.2 Hz, H-1a), 2.90 (dd,
1H, J1a,1b¼17.2 Hz, J1b,2¼6.6 Hz, H-1b), 3.21 (s, 3H, OMs), 4.48 (m, 2H,
H-2 and H-5), 4.63 (pseudo d, 2H, J5,6¼4.6 Hz, 2ꢂH-6), 5.20 (d, 1H,
J2,3¼3.5 Hz, H-3), 5.51 (d, 1H, J4,5¼3.4 Hz, H-4), 7.36–8.15 (m, 10H,
4.1.11. 2-(2,5:3,4-Dianhydro-1-deoxy-D-allitol-1-C-yl)thiazole-
4-carboxamide (3)
2ꢂPh). 13C NMR (CDCl3):
d
18.4 (C-1), 38.5 (OMs), 63.2 (C-6), 75.9 (C-
A solution of 23 (0.117 g, 0.2 mmol) in saturated methanolic
ammonia (5 mL), was stored at room temperature for 8 days. After
workup as described above (Section 4.1.4.), the mixture was
purified by preparative TLC (5:1 CHCl3/MeOH, eluted with 1:1
2), 79.0 (C-4), 81.5 (C-5), 82.5 (C-3), 116.3 (CN), 128.1, 128.4, 128.6,
129.3,129.7,129.8,133.3 and 134.1 (2ꢂPh), 165.4 and 166.1 (2ꢂPhCO).
LRMS (CI): m/z 460 (MHþ). Anal. Found: C, 57.29; H, 4.31; N, 2.67; S,
6.69. Calcd for C22H21NO8S: C, 57.51; H, 4.61; N, 3.05; O, S, 6.98.
iPrOH/EtOAc) to give pure 3 (0.030 g, 60%) as colourless crystals, mp
23
141–141.5 ꢀC, [
a
]
þ53.3 (c 0.45, MeOH), Rf¼0.6 (5:1 CHCl3/MeOH).
D
1H NMR (methanol-d4):
d
3.35 (d, 2H, J1 ,2 ¼7.0 Hz, 2ꢂH-1 ), 3.60
0
0
0
4.1.9. 3,6-Anhydro-5,7-di-O-benzoyl-2-deoxy-4-O-
methanesulfonyl-D-gluco-heptonthioamide (22)
Through a solution of 21 (0.50 g, 1.09 mmol) in dry pyridine
(3 mL) was passed H2S gas at room temperature for 14 days. After
workup as described above (Section 4.1.2.) followed by chro-
matographic purification on a column of flash silica (4:1 toluene/
(dd, 1H, J6a ,6b ¼11.8 Hz, J5 ,6a ¼5.2 Hz, H-6a0), 3.68 (dd, 1H,
0
0
0
0
0
0
0
0
0
0
0
0
J6a ,6b ¼11.8 Hz, J5 ,6b ¼4.1 Hz, H-6b ), 3.90 (d, 1H, J3 ,4 ¼2.8 Hz, H-4 ),
3.96 (d, 1H, J3 ,4 ¼2.8 Hz, H-30), 4.10 (dd, 01H, J5 ,6a ¼5.2 Hz,
0
0
0
0
0
0
0
0
0
J5 ,6b ¼4.1 Hz, H-5 ), 4.44 (t, 1H, J1 ,2 ¼7.0 Hz, H-2 ), 8.13 (s, 1H, H-5).
NOE contacts: H-10 and H-60, H-10 and H-30. 13C NMR (methanol-
EtOAc) pure 22 (0.420 g, 78%) was obtained as a colourless syrup,
d4): d
37.3 (C-10), 59.8 (C-40), 60.9 (C-30), 63.3 (C-60), 78.9 (C-20), 81.3
23
[
a]
ꢁ12.8 (c 1.76, CHCl3), Rf¼0.39 (7:3 toluene/EtOAc). 1H NMR
(C-50), 126.0 (C-5), 150.2 (C-4), 159.2 (C-2), 168.8 (CONH2). LRMS
(CI): m/z 257 (MHþ). Anal. Found: C, 46.90; H, 4.85; N, 10.81; S,
12.55. Calcd for C10H12N2O4S: C, 46.86; H, 4.69; N, 10.93; S, 12.53.
D
(CDCl3):
d
3.11 (d, 2H, J2,3¼6.2 Hz, 2ꢂH-2), 3.16 (s, 3H, OMs), 4.43
(m, 1H, J6,7¼4.5 Hz, H-6), 4.64 (d, 2H, 2ꢂH-7), 4.78 (td, 1H,
J2,3¼6.2 Hz, J3,4¼3.3 Hz, H-3), 5.24 (d, 1H, J3,4¼3.3 Hz, H-4), 5.48 (d,
1H, J5,6¼3.3 Hz, H-5), 7.40–8.15 (m, 10H, 2ꢂPh), 7.80–8.00 (2ꢂbr s,
4.1.12. 2-(2,5:3,4-Dianhydro-1-deoxy-D-altritol-1-C-yl)thiazole-
4-carboxamide (25)
2H, NH2). 13C NMR (CDCl3):
d
38.4 (OMs), 43.9 (C-2), 63.4 (C-7), 79.1
(C-5), 79.6 (C-3), 81.3 (C-6), 83.7 (C-4), 128.1, 128.2, 129.0, 129.3,
129.6, 129.8, 133.3 and 133.9 (2ꢂPh), 165.6 and 166.3 (2ꢂPhCO),
204.8 (CSNH2). Anal. Found: C, 50.90; H, 4.81; N, 2.63; S, 11.16. Calcd
for C22H23NO8S2ꢂ1.5H2O: C, 50.76; H, 5.03; N, 2.69; S, 12.32.
A solution of 24 (0.074 g, 0.12 mmol) in saturated methanolic
ammonia (3 mL) was kept at room temperature for 8 days. After
workup as described above (Section 4.1.4.), the mixture was
purified by preparative TLC (5:1 CHCl3/MeOH, eluted with 1:1
iPrOH/EtOAc) to afford pure 25 (0.021 g, 65%) as colourless crystals,
23
4.1.10. Ethyl 2-(2,5-anhydro-4,6-di-O-benzoyl-1-deoxy-3-O-
mp 200 ꢀC, [
a
]
D
þ4.0 (c 0.47, DMSO), Rf¼0.55 (5:1 CHCl3/MeOH).
1H NMR (DMSO-d6):
d
3.15 (dd, 1H, J1a ,1b ¼14.9 Hz, J10a ,2 ¼7.3 Hz, H-
0
0
0
0
methanesulfonyl-
ethyl 2-(2,5-anhydro-4,6-di-O-benzoyl-1-deoxy-3-O-
methanesulfonyl- -mannitol-1-C-yl)thiazole-4-carboxylate (24)
D
-glucitol-1-C-yl)thiazole-4-carboxylate (23) and
1a0), 3.28 (dd, 1H, J1a ,1b ¼14.9 Hz, J1b ,2 ¼5.7 Hz, H-1b ), 3.45 (m, 2H,
0
0
0
0
0
0
0
0
0
0
D
J5 ,6 ¼4.6 Hz, 2ꢂH-6 0), 3.79 (d, 1H, J3 ,4 ¼3.0 Hz, H-4 ), 3.96 (d,
0
0
0
0
0
A solution of 22 (0.485 g, 0.984 mmol) and ethyl bromopyruvate
(0.15 mL, 1.18 mmol) in absolute ethanol (7 mL), was refluxed for
1H, J3 ,4 ¼3.0 Hz, H-3 ), 3.99 (t, 1H, J5 ,6 ¼4.6 Hz, H-5 ), 4.37 (dd, 1H,
0
0
0
0
0
J1a ,2 ¼7.3 Hz, J1b ,2 ¼5.7 Hz, H-2 ), 4.94 (br t, 1H, exchangeable with

7644
M. Popsavin et al. / Tetrahedron 65 (2009) 7637–7645
D2O, OH), 7.52 and 7.71 (2ꢂbr s, 2H, NH2), 8.10 (s, 1H, H-5). NOE
contact: H-60 and H-40. 13C NMR (DMSO-d6): 34.6 (C-10), 57.7 (C-
30), 58.0 (C-40), 61.5 (C-60), 76.3 (C-20), 79.1 (C-50), 124.7 (C-5), 149.7
(C-4), 162.8 (C-2), 167.2 (CONH2). LRMS (CI): m/z 257 (MHþ). Anal.
Found: C, 46.96; H, 4.91; N,10.65; S,12.28. Calcd for C10H12N2O4S: C,
46.86; H, 4.69; N, 10.93; S, 12.53.
References and notes
d
1. For recent reviews on the chemistry of C-nucleosides, see: (a) Dolzhenko, A. V.;
Dolzhenko, A. V.; Chui, W. K. Heterocycles 2008, 75, 1575; (b) Merino, P.; Tejero,
T.; Delso, I. Curr. Med. Chem. 2008, 15, 954; (c) Enguehard-Gueiffier, C.; Gueiffier,
A. Mini-Rev. Med. Chem. 2007, 7, 888; (d) Wellington, K. W.; Benner, S. A. Nu-
cleosides Nucleotides Nucleic Acids 2006, 25, 1309; (e) Wu, Q.; Simons, C. Syn-
thesis 2004, 1533; (f) Pankiewicz, K. W.; Watanabe, K. A.; Lesiak-Watanabe, K.;
Goldstein, B. M.; Jayaram, H. N. Curr. Med. Chem. 2002, 9, 733; (g) Lamberth, C.
Org. Prep. Proced. Int. 2002, 34, 149.
4.2. Single crystal X-ray analysis19
2. For a brief overview of the biological and clinical impact of tiazofurin, see:
Grifantini, M. Curr. Opin. Invest. Drugs 2000, 1, 257.
3. (a) Malek, K.; Boosalis, M.; Waraska, K.; Mitchell, B. S.; Wright, D. G. Leukemia
Res. 2004, 28, 1125; (b) Wright, D. G.; Boosalis, M.; Malek, K.; Waraska, K.
Leukemia Res. 2004, 28, 1137.
Single crystals of compound 14 were grown from slow evapo-
ration of a solution of the compound in a mixture of CHCl3 and
hexane. Crystallographic data were measured on a Nonius Kappa
4. (a) Wright, D. G.; Boosalis, M. S.; Waraska, K.; Oshry, L. J.; Weintraub, L. R.;
Vosburgh, E. Anticancer Res. 1996, 16, 3349; (b) Tricot, G.; Weber, G. Anticancer
Res. 1996, 16, 3341; (c) Weber, G.; Nagai, M.; Natsumeda, Y.; Eble, J. N.; Jayaram,
H. N.; Paulik, E.; Zhen, W. N.; Hoffman, R.; Tricot, G. Cancer Commun. 1991, 3, 61.
5. For reviews on recent progress in the development of new drugs based on
inhibition of IMP dehydrogenase, see: (a) Shu, Q.; Nair, V. Med. Res. Rev. 2008,
28, 219; (b) Nair, V.; Shu, Q. Antiviral Chem. Chemother. 2007, 18, 245; (c) Pan-
kiewicz, K. W.; Patterson, S. E.; Black, P. L.; Jayaram, H. N.; Risal, D.; Goldstein, B.
M.; Stuyver, L. J.; Schinazi, R. F. Curr. Med. Chem. 2004, 11, 887; (d) Sintchak, M.
D.; Nimmesgern, E. Immunopharmacology 2000, 47, 163.
CCD area-detector diffractometer using
radiation (
u- and j-scans and Mo Ka
¼0.71073 Å). Experimental details from the structure
l
determinations are given in Table 2. The structure was resolved by
direct method (SHELXS-9720) and refined by full matrix least-
squares on F2 (SHELXL-9721
)
Table 2
Crystallographic data and structure refinement of 14
6. (a) Merino, P.; Tejero, T.; Unzurrunzaga, F. J.; Franco, S.; Chiacchio, U.; Saita, M.
G.; Iannazzo, D.; Pipernoc, A.; Romeo, G. Tetrahedron: Asymmetry 2005, 16,
3865; (b) Chiacchio, U.; Rescifina, A.; Saita, M. G.; Iannazzo, D.; Romeo, G.;
Mates, J. A.; Tejero, T.; Merino, P. J. Org. Chem. 2005, 70, 8991; (c) Chun, M. W.;
Kim, M. J.; Shin, J. H.; Jeong, L. S. Nucleosides Nucleotides Nucleic Acids 2005, 24,
975; (d) Cai, D.-M.; Lin, K. H.; Li, M.-Z.; Wen, J. W.; Li, H.-Y.; Jou, T.-P. Chin. J.
Chem. 2005, 22, 1425; (e) Nair, V.; Wenzel, T. ARKIVOC 2004, 14, 128; (f) Navarre,
J.-M.; Guianvarc’h, D.; Farese-Di Giorgio, A.; Condom, R.; Benhida, R. Tetrahe-
dron Lett. 2003, 44, 2199; (g) Liang, C. W.; Kim, M. J.; Jeong, L. S.; Chun, M. W.
Nucleosides Nucleotides Nucleic Acids 2003, 22, 2039; (h) Cappellacci, L.; Bar-
boni, G.; Franchetti, P.; Martini, C.; Jayaram, H. N.; Grifantini, M. Nucleosides
Nucleotides Nucleic Acids 2003, 22, 869; (i) Franchetti, P.; Marchetti, S.; Cap-
pellacci, L.; Yalowitz, J. A.; Jayaram, H. N.; Goldstein, B. M.; Grifantini, M. Bioorg.
Med. Chem. Lett. 2001, 11, 67; (j) Franchetti, P.; Marchetti, S.; Cappellacci, L.;
Jayaram, H. N.; Yalowitz, J. A.; Goldstein, B. M.; Barascut, J.-L.; Dukhan, D.;
Imbach, J.-L.; Grifantini, M. J. Med. Chem. 2000, 43, 1264; (k) Franchetti, P.;
Marchetti, S.; Cappellacci, L.; Grifantini, M.; Goldstein, B. M.; Dukhan, D.; Bar-
ascut, J.-L.; Imbach, J.-L. Nucleosides Nucleotides 1999, 18, 679; (l) Zhang, H. Y.;
Yu, H. W.; Ma, L. T.; Min, J. M.; Zhang, L. H. Tetrahedron: Asymmetry 1998, 9, 141;
(m) Franchetti, P.; Cappellacci, L.; Abu Seikha, G.; Jayaram, H. N.; Gurudutt, V.
V.; Sint, T.; Schneider, B. P.; Jones, W. D.; Goldstein, B. M.; Perra, G.; De Montis,
A.; Loi, A.; La Colla, G. P.; Grifantini, M. J. Med. Chem. 1997, 40, 1731; (n) Fran-
chetti, P.; Cappellacci, L.; Grifantini, M.; Barzi, A.; Nocentini, G.; Yang, H.;
O’Conor, A.; Jayaram, H. N.; Corell, C.; Goldstein, B. M. J. Med. Chem. 1995, 38,
3829.
Crystallographic parameter
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
C14H13NO4
259.25
150(2)
0.71073 [Mo K
Orthorhombic
P212121
a]
Space group
Unit cell dimensions
a¼5.5071(9)
b¼9.4337(11)
c¼23.674(3)
1229.9(3)
4
Volume (Å3)
Z
Density (calculated)
Absorption coefficient (mmꢁ1
F(000)
Crystal size
Data collection range
Index ranges
Reflections collected
Independent reflections
Observed reflections
Absorption correction
Max. and min. transmission
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
1.4 mg/m3
0.104
)
544
0.30 mmꢂ0.20 mmꢂ0.20 mm
1.72ꢃ
Q
ꢃ24.55ꢀ
ꢁ6ꢃhꢃ5, ꢁ11ꢃkꢃ11, ꢁ27ꢃlꢃ27
2368
1936 [R(int)¼0.0343]
1518 [I>2s(I)]
Multi-scan
0.9907 and 0.9676
Full
1936/0/172
1.123
ˇ
´
7. (a) Popsavin, M.; Spaic´, S.; Svircev, M.; Kojic, V.; Bogdanovic,
´
G.; Popsavin, V.
ˇ
Bioorg. Med. Chem. Lett. 2006, 16, 5317; (b) Popsavin, M.; Torovic´, Lj.; Svircev,
M.; Kojic´, V.; Bogdanovic´, G.; Popsavin, V. Bioorg. Med. Chem. Lett. 2006, 16,
2773; (c) Popsavin, M.; Torovic´, Lj.; Kojic´, V.; Bogdanovic´, G.; Popsavin, V.
´
´
Tetrahedron Lett. 2004, 45, 7125; (d) Popsavin, M.; Torovic, Lj.; Kojic, V.; Bog-
danovic´, G.; Spaic´, S.; Popsavin, V. Bioorg. Med. Chem. Lett. 2003, 13, 3167.
8. (a) Takatsuki, K.; Ohgushi, S.; Kohmoto, S.; Kishikawa, K.; Yamamoto, M. Nu-
cleosides Nucleotides Nucleic Acids 2006, 25, 719; (b) Li, Z.; Chen, S.; Jiang, N.;
Cui, G. Nucleosides Nucleotides Nucleic Acids 2003, 22, 419; (c) Dyatkina, N. B.;
Atrazheva, E. D.; Alexandrova, L. A.; Krayevsky, A. A.; von Janta-Lippinsky, M.
Bioorg. Khim. 1988, 14, 815; (d) Webb, T. R.; Mitsuya, H.; Broder, S. J. Med. Chem.
1988, 31, 1475.
Final R indices [I>2
s(I)]
R1¼0.0647, wR2¼0.1439
R indices
(all data)
Largest diff.
peak and hole
Absolute structure parameter
R1¼0.0919, wR2¼0.1671
0.366 and ꢁ0.41 e Åꢁ3
ꢁ1(3)
ˇ
9. For a preliminary account of this work see: Popsavin, M.; Spaic´, S.; Svircev, M.;
Kojic´, V.; Bogdanovic´, G.; Popsavin, V. Bioorg. Med. Chem. Lett. 2007, 17, 4123.
10. Brown, R. S.; Dowden, J.; Moreau, C.; Potter, B. V. L. Tetrahedron Lett. 2002, 43,
6561.
4.3. In vitro antitumour assay
Exponentially growing cells were harvested, counted by trypan
blue exclusion and plated into 96-well microtitar plates (Costar) at
optimal seeding density of 104 (K562, HL-60, Jurkat and Raji) or
5ꢂ103 (HT-29 and MCF-7) cells per well to assure logarithmic
growth rate throughout the assay period. Antiproliferative activity
was evaluated by the tetrazolium colorimetric MTT assay following
the recently reported procedure.22
´
´
´
11. Popsavin, M.; Popsavin, V.; Vukojevic, N.; Csanadi, J.; Miljkovic, D. Carbohydr.
Res. 1994, 260, 145.
12. Hantzsch, A.; Weber, J. H. Ber. Dtsch. Chem. Ges. 1887, 20, 3118.
13. (a) For a brief review on biological features of L-nucleoside analogues see:
Gumina, G.; Song, G.-Y.; Chu, C. K FEMS Microbiol. Lett. 2001, 202, 9.
14. Apart from the isolated products, several more polar components were also
detected in the reaction mixture. However, none of these by-products could be
obtained in pure form due to their similar chromatographic mobility.
15. For cyanide-catalyzed removal of acetate and benzoate groups in a variety of
sugar derivatives, see: (a) Herzig, J.; Nudelman, A.; Gottlieb, H. E.; Fischer, B. J.
Org. Chem. 1986, 51, 727; (b) Schuerch, C.; El-Shenawy, H. A. J. Carbohydr. Chem.
1985, 4, 215.
16. For application of benzoyl cyanide as benzoylating agent, see: (a) Lin, F. L.; van
Halbeek, H.; Bertozzi, C. R. Carbohydr. Res. 2007, 342, 2014; (b) Prasad, A. K.;
Kumar, V.; Malhotra, S.; Ravikumar, V. T.; Sanghvi, Y. S.; Parmar, V. S. Bioorg.
Med. Chem. 2005, 13, 4467; (c) Lay, L.; Windmuller, R.; Reinhardt, S.; Schmidt,
Acknowledgements
This work was supported by a research grant from the Ministry
of Science of the Republic of Serbia (Project No. 142005). The
authors are grateful to Dr. M. Thornton-Pett and Mr. C. A. Kilner
(University of Leeds, UK) for single crystal X-ray structure
determination.
ˇ
R. R. Carbohydr. Res. 1997, 303, 39; (d) Holy´, A.; Soucek, M. Tetrahedron Lett. 1971,
185.
17. The postulated intermediate 17 could not be detected in the reaction mixture.
However, a small amount of 17 (8%) was obtained from the reaction of 13 with

M. Popsavin et al. / Tetrahedron 65 (2009) 7637–7645
7645
KCN in the presence of BzCN (DMSO, 40–50 ꢀC, 44 h). 250 MHz 1H NMR (CDCl3):
free of charge, on application to CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK
[fax: þ44(0) 1223 336033 or e-mail: deposit@ccdc.cam.ac.uk].
20. Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467.
21. Sheldrick, G. M. SHELXL 93, Program for Refinement of Crystal Structures; Uni-
versity of Go¨ttingen: Go¨ttingen, 1993.
d
3.13 and 3.29 (2ꢂs, 3H each, 2ꢂOMs), 4.36 (m,1H, H-5), 4.51–4.74 (m, 5H, H-1,
H-2 and 2ꢂH-6), 5.35 (dd, 1H, H-3), 5.53 (dd, 1H, H-4), 7.32–8.14 (m, 10H, 2ꢂPh).
18. Cupps, T. L.; Wise, D. S.; Townsend, L. B. J. Org. Chem. 1986, 51, 1058.
19. Crystallographic data (excluding structure factors) for the structure 14 have
been deposited with the Cambridge Crystallographic Data Centre as supple-
mentary publication number CCDC 706390. Copies of the data can be obtained,
22. Popsavin, V.; Krstic´, I.; Popsavin, M.; Srec´o, B.; Benedekovic´, G.; Kojic´, V.;
´
Bogdanovic, G. Tetrahedron 2006, 62, 11044.