Design, synthesis and antiproliferative activity of styryl lactones related to (+)-goniofufurone

Article abstract of DOI:10.1016/j.ejmech.2010.03.010

This paper describes a straightforward divergent synthesis of (+)-goniofufurone mimics (4, 5 and 6) starting from d-xylose. In a preliminary bioassay, analogues 4 and 5 exhibited a submicromolar antiproliferative activity towards HL-60 cells, while the co

Full text of DOI:10.1016/j.ejmech.2010.03.010

European Journal of Medicinal Chemistry 45 (2010) 2876e2883
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Design, synthesis and antiproliferative activity of styryl lactones related
to (þ)-goniofufurone
,
a
a
a
Velimir Popsavin a , Bojana Sreco , Goran Benedekovic , Jovana Francuz , Mirjana Popsavin ,
ꢀ a
*
ꢀ
ꢀ b
ꢀ b
Vesna Kojic , Gordana Bogdanovic
a
ꢀ
Department of Chemistry, Faculty of Sciences, University of Novi Sad, Trg D. Obradovica 3, 21000 Novi Sad, Serbia
b Oncology Institute of Vojvodina, 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:
This paper describes a straightforward divergent synthesis of (þ)-goniofufurone mimics (4, 5 and 6)
Received 10 November 2009
Received in revised form
25 February 2010
Accepted 9 March 2010
Available online 12 March 2010
starting from D-xylose. In a preliminary bioassay, analogues 4 and 5 exhibited a submicromolar anti-
proliferative activity towards HL-60 cells, while the corresponding parent compound 1 was completely
inactive against this cell line. At the same time, these molecules showed approximately 10-fold stronger
cytotoxicity in the same cell line when compared to the standard anticancer drug doxorubicin (DOX).
Analogue 6 displayed 18- and 3-fold higher potency in Raji cell line when compared to control
compounds 1 and DOX, respectively. A new divergent route for the preparation of (þ)-goniofufurone (1)
Keywords:
and (þ)-crassalactone C (3) from
D
-xylose is also disclosed.
Ó 2010 Elsevier Masson SAS. All rights reserved.
Styryl lactones
Crassalactone C
Goniofufurone
Antitumour agents
Analogues
Antiproliferatve activity
SAR
1. Introduction
having
synthesis of a number of styryl lactones by chirality transfer from
-xylose [19e21]. In continuation of this strategy, we report herein
on the synthesis and preliminary in vitro antitumour screening of
new styryl lactones 4, 5 and 6 as possible (þ)-goniofufurone
mimics. Compound 4 was designed as a conformationally flexible
analogue of (þ)-goniofufurone (1) and may be formally derived
from 1 through a cleavage of the C3eO6 bond. In the same time,
g-lactone rings and have recently accomplished the total
Phytochemical studies of the genus Goniothalamus have resul-
ted in the isolation and characterization of many compounds with
a variety of biological activity [1,2]. Due to their proven use in folk
medicine in Taiwan, Malaysia, and India to treat rheumatism,
edema, as abortifacients, and as mosquito repellents, there has
been an interest in the active ingredients as potential therapeutic
targets. This resulted in the isolation by McLaughlin et al. [3e5] of
a series of styryl lactones which were reported to show anti-
tumour, pesticidal, and embryotoxic activities. Amongst these,
(þ)-goniofufurone (1, Fig. 1) containing a furano-furone bicyclic
core has shown significant cytotoxic activities against several
human tumour cell lines [6,7]. Due to its unique and intriguing
structure, as well as its promising antitumour activity this natural
product along with a number of its analogues has attracted the
attention of many synthetic groups [8e18]. We have been involved
in the synthesis of bio-active natural products and analogues
D
molecule
diobutanolide (2),
4
represents
a
3-deoxy derivative of (þ)-car-
a
naturally occurring styryl lactone that
was recently isolated from the stem bark of Goniothalamus
cardiopetalus [22]. Both furano-lactones 5 and 6 were designed as
less polar analogues of (þ)-goniofufurone (1). Enhanced lipophilic
character of
5 and 6 should improve their cell membrane
permeation that may be beneficial for their antitumour activity.
On the other hand, molecule 5 might be considered as a non-
vinylogous analogue of (þ)-crassalactone C (3), the naturally
occurring styryl lactone that was very recently isolated from the
leaves and twigs of Polyalthia crassa [23]. Apart from the synthesis
of 4e6, a novel divergent route to 1 and 3 was also developed in
order to provide samples of the leads that would serve as positive
controls in antitumour assays.
* Corresponding author. Tel.: þ381 21 485 27 68; fax: þ381 21 454 065.
E-mail address: velimir.popsavin@dh.uns.ac.rs (V. Popsavin).
0223-5234/$ e see front matter Ó 2010 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2010.03.010

V. Popsavin et al. / European Journal of Medicinal Chemistry 45 (2010) 2876e2883
2877
Meldrum’s acid [26]. Accordingly, compound 10 was allowed to
react with Meldrum’s acid in DMF, in the presence of Et3N,
whereupon the protected lactone 11 was obtained in 73% yield.
Intermediate 11 was finally converted to (þ)-goniofufurone (1)
after hydrogenolytic removal of both benzyl protective groups
(H2-Pd/C, MeOH). This synthetic sequence, which produced the
target 1 in 35% overall yield (from 8), is somewhat less efficient
with respect to that previously completed in our laboratory (43%
overall yield) [20,21]. The physical and spectroscopic data of thus
prepared sample 1 are in good agreement with the literature
values [18].
The synthesis of (þ)-crassalactone C (3) commenced with
a conversion of 8 into the corresponding 5-O-cinnamoyl derivative
12. Accordingly, compound 8 was treated with cinnamic acid and
DCC, in anhydrous CH2Cl2 and in the presence of DMAP, to afford
an almost quantitative yield of 12. The intermediate 12 was con-
verted to the protected lactone 14 by using the same methodology
as that already applied for the conversion of 9e11. Thus, treatment
of 12 with aqueous acetic acid gave the expected lactol 13 (73%),
while the concomitant condensation of 13 with Meldrum’s acid
furnished 14 in 73% yield. Moreover, oxidative cleavage [27] of the
benzyl protecting group in 14 (DDQ, CHCl3, H2O) gave (þ)-cras-
salactone C (3), with physical and spectral properties in full
agreement with those previously reported [20,21,23]. This new
synthesis of 3 proceeds in eleven linear steps with 15.2% overall
Fig. 1. Naturally occuring styryl lactones and analogues.
2. Results and discussion
2.1. Chemistry
The divergent synthesis of natural products 1 and 3 is outlined
in Scheme 1. The known [20,21] alcohol 8 that is readily available
yield calculated to starting -xylose derivative 7. The preceding
D
from partially protected
D
-xylose derivative 7 [24], was conve-
preparation of 3 was accomplished in 7.8% overall yield over ten
linear steps [20,21].
niently used as a common intermediate for the preparation of both
targets 1 and 3.
The synthesis of analogues 4, 5 and 6 is shown in Scheme 2. The
known [20,21] 5-O-benzoyl derivative 15 has served as a convenient
starting compound for the preparation of both targets 4 and 5, via
the lactol 16 as a common intermediate. Thus, hydrolytic removal
of the cyclohexylidene protective group in 15 with diluted acetic
acid, gave the lactol 16 (78%). Wittig olefination of 16 with
Ph3P]CHCO2Me in DMF took place stereoselectively to afford the
(E)-unsaturated ester 17 in 69% yield. Catalytic hydrogenation of 17
over 10% Pd/C in methanol yielded the saturated ester 18 (72%).
Sodium methoxide O-debenzoylation of 18 occurred with
concomitant lactonisation to afford the target 4 ready for biological
testing.
For the sake of synthesis of 1, compound 8 was first converted
to the corresponding di-O-benzyl ether 9 (94%) by treatment
with BnBr (NaH, DMF). Hydrolytic removal of the cyclo-
hexylidene protective group in 9 with aqueous acetic acid gave
a 69% yield of the known lactol 10, with physical constants (mp
and optical rotation) in good agreement with those previously
reported [25]. Compound 10 may be converted to the target 1 via
the reported two-step sequence which consists of a Z-selective
Wittig olefination, followed by hydrogenolytic removal of both
benzyl ether protective groups [25]. However, we wanted to
explore an alternative method for elaboration of the required
[3.3.0] bicyclic lactone core based on the condensation of 10 with
Scheme 1. Reagents and conditions: (a) Ref. 20, 33.8% from 7 steps; (b) BnBr, NaH, DMF, 0ꢀC for 1 h, then rt for 0.5 h, 94%; (c) 70% aq AcOH, reflux, 5 h for 9, 69% of 10, 12 h for 12,
73% of 13; (d) Meldrum’s acid, Et3N, DMF, 46e48 ꢀC, 72 h for 10, 73% of 11, 65 h for 13, 73% of 14; (e) H2-Pd/C, MeOH, rt, 9 days, 74%; (f) cinnamic acid, DCC, DMAP, CH2Cl2, rt, 24 h,
97%; (g) DDQ, 10:1 CHCl3/H2O, reflux, 30 h, 87%.

2878
V. Popsavin et al. / European Journal of Medicinal Chemistry 45 (2010) 2876e2883
Scheme 2. Reagents and conditions: (a) 70% aq AcOH, reflux, 7 h for 15, 78% of 16, 3 h for 21, 49% of 22; (b) Ph3P]CHCO2Me, DMF, 70 ꢀC, 5 h, 69%; (c) H2-Pd/C, MeOH, rt, 4 h, 72%;
(d) NaOMe, MeOH, rt, 1 h, 69%; (e) Ph3P]CHCO2Me, MeOH, ꢁ20 ꢀC for 1 h, then rt for 47 h, 52%; (f) Meldrum’s acid, Et3N, DMF, 46ꢀC, 65 h for 16, 58% of 19, 48 h for 22, 52% of 6; (g)
H2-Pd/C, HCl (cat.), EtOAc, rt, 44 h, 76% of 5, 22% of 6; (h) Ph3P, DEAD, MePh, reflux, 2.5 h, 73%; (i) PhMgBr/Et2O, THF, reflux, 8.5 h, 85%.
As mentioned above, the lactol 16 represents a divergent
intermediate for the preparation of target 5. At this point, we
wanted to examine both methods for elaboration of the bicyclic
lactone core in 5; the Z-selective Wittig reaction [28] of 16 with
Ph3P]CHCO2Me, as well as the condensation of Meldrum’s acid
with 16. When lactol 16 was reacted with the stabilized ylide
Ph3P]CHCO2Me in dry methanol the expected furano-lactone 19
was obtained in 52% yield. Alternatively, when the lactol 16 was
allowed to react with Meldrum’s acid, in dry N,N-dimethylforma-
mide and in the presence of triethyl amine, the desired lactone 19
was obtained in 58% yield. The last procedure for preparation of 19
is more convenient then that based upon the Wittig reaction, not
only because of slightly higher yield, but also due to easier product
isolation from the reaction mixture. The 5-O-Benzyl protecting
group from 19 was removed by catalytic hydrogenolysis to give
analogue 5 (76%) as a major reaction product.
yield. Hydrolytic removal of the cyclohexylidene protective group
(7:3 aq AcOH), followed by the -lactone formation (Meldrum’s
acid, Et3N, DMF) afforded the furano-lactone 6. This compound was
previously obtained as a side-product in the final step of the
Murphy and Dennison’s synthesis of goniofufurone [32]. X-ray data
g
of 6 were also reported [33]. Although the melting point and the
20
optical rotation {mp 139 ꢀC, [
a]
þ49.5 (c 0.62, CHCl3)} of thus
D
obtained sample 6 are different from the literature values {mp
20
101e103 ꢀC, [
a]
þ37.0 (c 0.14, CHCl3)}, the 1H and 13C NMR
D
spectral data are in good agreement with the reported values [32].
2.2. In vitro cytotoxic activity
Compounds 4, 5 and 6 were evaluated for their in vitro cyto-
toxicity against human myelogenous leukaemia (K562), human
promyelocytic leukaemia (HL-60), human T cell leukaemia (Jurkat),
human Burkitt’s lymphoma (Raji cells) human cervix carcinoma
(HeLa) and normal foetal lung fibroblasts (MRC-5). Cytotoxic
activity was evaluated by using the standard MTT colorimetric
assay after exposure of cells to the test compounds for 72 h.
(þ)-Goniofufurone (1), (þ)-crassalactone C (3) and the commercial
antitumour agent doxorubicin (DOX) were used as reference
compounds. According to the resulting IC50 values of the cytotoxic
assay (Table 1), all three styryl lactone analogues (4e6) exhibit
potent anticancer activities towards the most tested cell lines, with
IC50 values in the low-micromolar range. The only exception is
analogue 6, which showed a moderate cytotoxicity against the
HL-60 cells. Analogues 4 and 6 showed submicromolar activities
against K562 cells, with IC50 values comparable to that recorded for
the parent natural product 1. The 7-O-benzoyl derivative 5 is the
most cytotoxic molecule in this cell line, being essentially as potent
as the commercial antitumour agent doxorubicin (DOX). Remark-
ably, analogues 4 and 5 demonstrated the most potent activity
A minor amount of 7-deoxy derivative 6 (22%) was also obtained
from the last reaction (19/5). As we intended to evaluate its
antitumour activity, it was desirable to develop a more efficient
route for the preparation of 6. Accordingly, we envisaged a four-
step sequence, based on a nucleophilic oxetane ring opening in 20.
Compound 20 is usually prepared by
comprised of an initial regioselective 5-O-sulfonylation of 1,2-O-
cyclohexylidene- -xylofuranose (7), followed by a base-catalysed
a two-step sequence
a-D
3,5-anhydro ring closure [29]. For the purpose of this work we have
developed a one-step procedure for preparation of 20 under the
Mitsunobu cyclodehydration conditions [30,31]. Thus, compound 7
was treated with diethyl azodicarboxylate and triphenylphosphine
in refluxing toluene, whereupon the oxetane 20 was obtained as
a main reaction product in 73% yield. The physical and spectral data
of thus prepared sample 20 were in good agreement with those
reported in the literature [29]. Treatment of 20 with phenyl-
magnesium bromide produced the expected alcohol 21 in 85%

V. Popsavin et al. / European Journal of Medicinal Chemistry 45 (2010) 2876e2883
2879
Table 1
Antiproliferative activities of synthesized compounds and DOX.
Compound
IC50
,
m
Ma
K562
HL-60
Jurkat
Raji
HeLa
8.32 (0.78)
11.25 (0.60)
2.34 (0.34)
5.69 (0.08)
4.42 (0.42)
0.07 (0.001)
MRC-5
1
3
4
5
6
DOX
0.41 (0.01)
3.56 (0.03)
0.54 (0.022)
0.23 (0.03)
0.51 (0.02)
0.25 (0.04)
>100 (5.32)
>100 (5.36)
0.09 (0.006)
0.12 (0.01)
43.81 (2.45)
0.92 (0.04)
32.45 (1.35)
25.45 (0.98)
2.23 (0.11)
0.36 (0.002)
2.52 (0.04)
0.03 (0.0018)
18.45 (1.98)
15.46 (1.02)
2.21 (0.67)
1.01 (0.05)
1.03 (0.24)
2.98 (0.09)
>100 (6.78)
>100 (8.98)
>100 (7.45)
>100 (6.97)
>100 (8.86)
0.10 (0.03)
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 experiments
done in quadriplicates. Standard deviations are given in parentheses.
against HL-60 cells being essentially 10-fold more active than DOX,
while the parent compound 1 was completely inactive in the same
cell line. All synthesized analogues (4e6) exhibited notable anti-
proliferative effects on Jurkat cells, with IC50 values in the
low-micromolar range. The most active molecule against this cell
line was 7-O-benzoyl derivative 5 being over 90-fold more potent
than 1, while analogues 4 and 6 demonstrated 14- and 12-fold
stronger cytotoxicity when compared to the parent natural product
1. The most active molecules against Raji cells are analogues 5 and 6
that exhibited over 18-fold higher potency than the control
compound 1, as well as almost 3-fold stronger growth inhibitory
activity with respect to doxorubicin. The ring-opened analogue 4
also showed a notable activity against this cell line, being over
8-fold more active than 1. In the same time, this molecule showed
a similar activity as DOX in the same cell line. All three styryl
lactones 4e6 exhibit micromolar cytotoxicity against HeLa malig-
which represent goniofufurone derivatives of enhanced lipophilic
character, were designed by formal displacement of the C-7
hydroxyl function with OBz or H, respectively. Molecule 5 may also
be considered as a de-vinylated analogue of the naturally occurring
styryl lactone (þ)-crassalactone C (3). All three analogues 4e6
exhibit potent to moderate antiproliferative activities against the
all tested neoplastic cells, but were devoid of any cytotoxic activity
towards the normal foetal lung MRC-5 fibroblasts. Analogues 4 and
5 demonstrated the most potent activity against HL-60 cells being
approximately 10-fold more cytotoxic than the standard anti-
tumour agent doxorubicin. The parent compound 1 however, was
completely inactive towards this cell line. Against the Raji cells,
both 5 and 6 exhibited over 18-fold higher potency than the
reference compound 1, as well as almost 3-fold stronger cytotox-
icity with respect to DOX. Based upon these results, we believe that
compounds 4e6 may serve as convenient leads in the search for
more potent and selective antitumour agents. Further optimization
of the structures, as well as the preparation of a number of new
(þ)-goniofufurone and (þ)-crassalactone C mimics to perform
structureeactivity relationship (SAR) is currently underway.
nant cells, with IC50 values ranging from 2.34 to 5.69 mM. The most
active compound against these cells is the monocyclic lactone 4,
being over 3-fold more cytotoxic than the parent compound 1. The
7-O-benzoyl derivative 5 demonstrated a similar potency as 1
against HeLa cells, while the 7-deoxy derivative 6 displayed almost
2-fold higher potency in the same cell line when compared to
control compound 1. The data obtained indicated that the THF ring
opening in 1, as well as the replacement of the C-7 hydroxyl
function, may enhance the antitumour activity of resulting
analogues in vitro. However, a comparison of biological data of 5
and 3 revealed that analogue 5 showed a superior activity against
the all tested cells. It appears that the removal of double bond from
4. Experimental
4.1. General
Melting points were determined on a Büchi 510 apparatus and
were not corrected. Optical rotations were measured on a KRÜSS
P3002 polarimeter at room temperature. IR spectra were recorded
with a FTIR/NIR Nexus 670 spectrophotometer (Thermo-Nicolet).
NMR spectra were recorded on a Bruker AC 250 E instrument and
chemical shifts are expressed in ppm downfield from TMS. Low
resolution mass spectra were recorded on Finnigan-MAT 8230 (CI)
and on an Agilent Technologies HPLC/MS 3Q system, series 1200/
6410 (ESI). High resolution mass spectra were taken on a 6210
Time-of-Flight LC/MS Agilent Technologies instrument (ESI). Flash
column chromatography was performed using ICN silica 32e63.
TLC was performed on DC Alufolien Kieselgel 60 F254 (E. Merck). All
organic extracts were dried with anhydrous Na2SO4. Organic
solutions were concentrated in a rotary evaporator under dimin-
ished pressure at a bath temperature below 30 ꢀC.
3
significantly increases the antiproliferative activity of the
analogue. The difference of the potency between these two mole-
cules could be due to different size of the aromatic ester groups in
their structures. Moreover, the all synthesized lactones 4, 5 and 6,
including the natural products 1 and 3 were found to be completely
inactive against the normal MRC-5 cells. These results do suggest
that these molecules represent selective antitumour agents, but
this should be verified by additional in vitro experiments with
different normal cell lines.
It is obvious that natural styryl lactones and analogues
demonstrate promising antitumour activities. Some possible
mechanisms of action of this class of biologically active molecules
have been recently reviewed [6,7]. However, a more comprehen-
sive biological studies will be required to identify the exact mode of
action of these compounds in tumour cells.
4.1.1. 3,5-Di-O-benzyl-1,2-O-cyclohexylidene-5-C-phenyl-a-D-
gluco-pentofuranose (9)
To a cooled (0 ꢀC) and stirred solution of 8 (0.141 g, 0.36 mmol)
in dry DMF (5 mL) were added successively 80% NaH (0.021 g,
0.69 mmol) and BnBr (0.055 mL; 0.46 mmol). The mixture was
stirred at 0 ꢀC for 1 h and then at room temperature for 0.5 h.
Methanol (2 mL) was finally added, and the mixture was stirred at
room temperature for the additional 15 minutes and evaporated.
The residue was suspended in water (30 mL) and extracted with
CH2Cl2 (2 ꢂ 15 mL). The combined organic solutions were dried and
evaporated. The remaining crude 9 (0.18 g) was purified by flash
3. Conclusions
In summary, we have developed an efficient divergent route to
several styryl lactones related to (þ)-goniofufurone (1) and evalu-
ated them for in vitro cytotoxic activities against five human
malignant cell lines. Molecule 4 was designed as a ring-opened
analogue of (þ)-goniofufurone (1) that was formally derived from 1
through a cleavage of the C3eO6 bond. Both analogues 5 and 6,

2880
V. Popsavin et al. / European Journal of Medicinal Chemistry 45 (2010) 2876e2883
column chromatography (9:1/4:1 light petroleum/Et2O) to afford
J3,4 ¼ 4.2 Hz, H-4), 5.08 (dd, 1 H, J2b,3 ¼ 5.6, J3,4 ¼ 4.2 Hz, H-3), 5.12
(d, 1 H, J6,7 ¼ 5.3 Hz, H-7), 7.30e7.44 (m, 5 H, Ph). 13C NMR (CDCl3):
20
pure 9 (0.164 g, 94%) as a colourless syrup, [
a
]
ꢁ36.46 (c 0.84,
D
CHCl3), Rf ¼ 0.43 (4:1 hexane/Et2O). 1H NMR (CDCl3):
d
1.33e1.78
d 36.1 (C-2), 73.5 (C-7), 74.4 (C-5), 77.3 (C-3), 82.9 (C-6), 87.4 (C-4),
(m,10 H, C6H10), 3.37e4.27 (m, 2 H, J3,4 ¼ 3.0, Jgem ¼ 11.0 Hz, H-3 and
PhCHa), 4.38e4.52 (m, 2 H, J3,4 ¼ 3.0, J4,5 ¼ 9.1, Jgem ¼ 11.0 Hz, H-4
and PhCHb), 4.67 (d, 1 H, J1,2 ¼ 3.7 Hz, H-2), 4.68 and 4.79 (2 ꢂ d, 1 H
each, Jgem ¼ 11.6 Hz, PhCH2), 4.80 (d, 1 H, J4,5 ¼ 9.1 Hz, H-5), 5.94
(d, 1 H, J1,2 ¼ 3.7 Hz, H-1), 7.18e7.60 (m, 15 H, 3 ꢂ Ph). 13C NMR
125.8, 128.5, 128.8 and 138.8 (Ph), 175.4 (C-1). HRMS (ESI): Found:
251.0912 (Mþ þ H), calcd for C13H15O5: 251.0914.
4.1.5. 1,2-O-cyclohexylidene-3-O-benzyl-5-O-cinnamoyl-5-C-
phenyl-a-D-gluco-pentofuranose (12)
(CDCl3):
d
23.5, 23.7, 24.8, 35.6 and 36.2 (5 ꢂ CH2), 70.2 and 72.3
To a solution of 8 (0.115 g, 0.29 mmol) in dry CH2Cl2 (11 mL)
were added successively cinnamic acid (0.086 g, 0.58 mmol), DCC
(0.144 g, 0.7 mmol) and DMAP (0.142 g, 1.16 mmol). The mixture
was stirred at room temperature for 24 h then poured into H2O
(80 mL) and extracted with CH2Cl2 (3 ꢂ 15 mL). The combined
extracts were washed with 10% NaCl (80 mL) dried and evaporated.
The residue was purified by flash column chromatography (5:1
light petroleum/Et2O) to afford pure 12 (0.148 g, 97%) as a colour-
(2 ꢂ PhCH2), 78.2 (C-5), 81.5 (C-2), 81.9 (C-3), 82.7 (C-4),104.5 (C-1),
112.1 (Cq from C6H10), 127.4, 127.48, 127.5, 127.7, 127.8, 127.9, 128.0,
128.2, 128.3, 128.4, 137.7, 138.1, 139.3 (3 ꢂ Ph). LRMS (CI): m/z 487
(Mþ þ H). Anal. Found: C, 72.76; H, 7.03. Calcd for C24H28O5∙1.5H2O:
C, 72.49; H, 7.26.
4.1.2. 3,5-Di-O-benzyl-5-C-phenyl- -gluco-pentofuranose (10)
D
A solution of 9 (0.159 g, 0.33 mmol) in 70% aq. AcOH (6 mL) was
stirred for 5 h under reflux. After the mixture cooled to room
temperature it was concentrated by co-distillation with toluene
and the residue (0.142 g) purified by flash column chromatography
(3:2 Et2O/light petroleum) to afford pure 10 (0.092 g, 69%) as
less syrup. Crystallization from MeOH/H2O gave colourless crystals,
20
mp 63 ꢀC, [
a
]
þ31.88 (c 1, CHCl3), Rf ¼ 0.6 (1:1 hexane/Et2O). IR
D
(KBr): nmax 1716 (C]O), 1637 (C]C, cinnamoyl). 1H NMR (CDCl3):
d
1.35ꢁ1.77 (m, 10 H, C6H10), 4.17 (d, 1 H, J3,4 ¼ 3.1 Hz, H-3), 4.52 and
4.70 (2 ꢂ d, 2 H, Jgem ¼ 11.6 Hz, PhCH2), 4.59 (dd, 1 H, J4,5 ¼ 9.6 Hz,
H-4), 4.68 (d, 1 H, J1,2 ¼ 3.7 Hz, H-2), 5.95 (d, 1 H, J1,2 ¼ 3.7 Hz, H-1),
a colourless solid. Recrystallization from CH2Cl2/hexane gave col-
20
ourless needles, mp 100e101 ꢀC, [
a
]
ꢁ6.81 (c 1.4, CHCl3),
6.15 (d, 1 H, J4,5 ¼ 9.6 Hz, H-5), 6.36 (d, 1 H, J2 ,3 ¼16.2 Hz, H-2 ),
0
0
0
D
20
Rf ¼ 0.44 (4:1 Et2O/hexane); lit. [25] mp 98e99 ꢀC, [
a
]
D ꢁ8.2 (c 1.0,
7.16e7.56 (m, 15 H, 3 ꢂ Ph), 7.64 (d, 1 H, J2 ,3 ¼16.2 Hz, H-3 ). 13C
0
0
0
CHCl3). IR (CHCl3): nmax 3380 (OH). 1H NMR (CDCl3 þ D2O):
d
4.05
NMR (CDCl3):
d
23.5, 23.8, 24.8, 35.6 and 36.3 (5 ꢂ CH2), 72.0
(dd, 1 H, J1,2 ¼ 4.0, J2,3 ¼1.7 Hz, H-2
a
), 4.10e4.79 (m, 6.6 H), 5.01
(PhCH2), 72.2 (C-5), 80.8 (C-3), 81.2 (C-2), 81.3 (C-4), 104.8 (C-1),
112.3 (Cq from C6H10), 117.8 (C-20), 127.4, 127.8, 128.0, 128.17, 128.2,
128.3, 128.5, 128.8, 130.3, 134.2, 136.8 and 138.2 (3 ꢂ Ph), 144.9
(C-30), 164.9 (C-10). LRMS (ESI): m/z 565 (Mþ þ K), 549 (Mþ þ Na),
527 (Mþ þ H). Anal. Found: C, 75.59; H, 6.14. Calcd for C26H28O6: C,
75.26; H, 6.51.
(s, 0.4 H, H-1
b
), 5.36 (d, 1 H, J1,2 ¼ 4.0 Hz, H-1
a
), 7.25e7.63 (m, 15 H,
70.2, 70.3, 72.4, 73.3, 74.6, 77.2, 78.4,
), 103.2 (C-1 ), 127.5, 127.6,
3 ꢂ Ph). 13C NMR (CDCl3):
d
79.4, 81.7, 82.0, 83.4, 84.3, 96.3 (C-1
a
b
127.8, 127.9, 127.93, 128.1, 128.15, 128.2, 128.3, 128.4, 128.41, 128.5,
128.6, 137.0, 137.9, 138.1, 138.14, 139.3 and 139.4 (3 ꢂ Ph). LRMS (CI):
m/z 407 (Mþ þ H).
4.1.6. 3-O-benzyl-5-O-cinnamoyl-5-C-phenyl-a-D-gluco-
4.1.3. 3,6-Anhydro-5,7-di-O-benzyl-2-deoxy-7-C-phenyl-
-ido-heptono-1,4-lactone (11)
To a solution of 10 (0.045 g, 0.11 mmol) in dry DMF (1 mL) was
added Meldrum’s acid (0.024 g, 0.17 mmol) and dry Et3N (0.023 mL,
0.16 mmol). The mixture was stirred for 72 h at 46e48 ꢀC and
evaporated. Flash column chromatography (4:1/2:3 hexane/Et2O)
D
-glycero-
pentofuranose (13)
D
A solution of 12 (0.211 g, 0.40 mmol) in 70% aq AcOH (7 mL) was
stirred for 12 h under reflux. After workup as described above
(Procedure 4.1.2.) crude 13 (0.192 g) remained as a yellow oil. Flash
column chromatography (1:1 hexane/EtOAc) of the residue gave
two fractions. Unreacted starting compound 12 (0.020 g, 11.3%) was
first eluted, followed by pure 13 (0.13 g, 73%), as a mixture of
of the residue gave pure 11 (0.035 g, 73%) as a colourless syrup,
20
[
[
a
a
]
]
ꢁ0.8 (c 0.93, CHCl3), Rf ¼ 0.23 (3:2 Et2O/hexane); lit. [25]
corresponding anomers (
a
/
b
z 2:1, from 1H NMR). Crystallization
20D
20
ꢁ5.8 (c 1.0, CHCl3). IR (CHCl3): nmax 1789 (C]O). 1H NMR
from MeOH/H2O gave colourless crystals, mp 106 ꢀC, [
a]
þ87.5
D
D
(CDCl3 þ D2O):
d
2.49 (d, 1 H, J2a,2b ¼ 18.9 Hz, H-2a), 2.63 (dd, 1 H,
(c 1.0, CHCl3), Rf ¼ 0.3 (1:1 hexane/EtOAc). IR (KBr): nmax 3430 (OH),
1709 (C]O), 1636 (C]C, cinnamoyl). 1H NMR (CDCl3):
2.42, 2.97,
3.71 and 3.95 (4 ꢂ bs, exchangeable with D2O, 2 ꢂ OH and ),
4.01e4.23 (m, H-2 , H-2 , H-3 and 3 ), 4.46e4.77 (m, PhCH2
and , H-4 and ), 5.04 (s, H-1 ), 6.07
), 5.37 (d, J1,2 ¼ 3.7 Hz, H-1
), 6.36
J2a,2b ¼ 18.9, J2b,3 ¼ 5.4 Hz, H-2b), 4.22 (dd,
1
H, J5,6 ¼ 3.1,
d
J6,7 ¼ 8.8 Hz, H-6), 4.28 and 4.42 (2 ꢂ d, 1 H each, Jgem ¼ 11.4 Hz,
PhCH2), 4.47 (d, 1 H, J5,6 ¼ 3.1 Hz, H-5), 4.65e4.77 (m, 3 H, H-4, H-7
and PhCHa), 4.86e4.96 (m, 2 H, H-3 and PhCHb), 7.21e7.51 (m, 15 H,
a
b
a
b
a
b
a
b
a
b
b
a
3 ꢂ Ph). 13C NMR (CDCl3):
d
35.8 (C-2), 70.1 and 73.2 (2 ꢂ PhCH2),
(d, J4,5 ¼ 9.2 Hz, H-5
a
), 6.15 (d, J4,5 ¼ 9.8 Hz, H-5
b
(d, J2 ,3 ¼15.9 Hz, H-20a), 6.37 (d, J2 ,3 ¼15.9 Hz, H-20b), 7.22e7.57
0
0
0
0
76.8 and 78.0 (C-4 and C-7), 80.8 (C-5), 83.3 (C-6), 84.9 (C-3), 127.5,
127.7, 127.8, 128.0, 128.3, 128.5, 128.52, 129.12,137.2, 137.9 and 139.0
(3 ꢂ Ph), 175.5 (C-1).
(m, 15 H, 3 ꢂ Ph), 7.63 (d, H-30
a b
), 7.64 (d, H-30 ). 13C NMR (CDCl3):
d
72.2 (PhCH2a), 72.8 (C-5
a
), 72.9 (PhCH2b), 73.2 (C-5
), 81.1 (C-3 ), 82.3 (C-3 ), 82.7 (C-4
), 117.7 (C-20 ), 117.8 (C-20
), 127.6, 127.8, 128.1,
b), 74.4 (C-2
a),
76.8 (C-2
b
), 80.2 (C-4
a
b
a
b), 96.4
4.1.4. (þ)-Goniofufurone (1)
(C-1 ), 103.6 (C-1
a
b
b
a
A solution of 11 (0.103 g, 0.24 mmol) in MeOH (5 mL) was
hydrogenated over 10% Pd/C (0.1 g) for 9 days at room temperature.
The mixture was filtered through a celite pad and the catalyst
washed with MeOH. The combined organic solutions were evapo-
rated and the residue was purified by flash chromatography (Et2O)
128.2, 128.3, 128.4, 128.5, 128.7, 128.9, 130.4, 130.5, 134.1, 134.2,
137.1, 138.2 and 138.3 (3 ꢂ Ph), 145.1 (C-30
a b), 165.1
), 145.3 (C-30
(C-10
a
), 165.2 (C-10
b
). LRMS (ESI): m/z 485 (Mþ þ K), 469 (Mþ þ Na).
HRMS (ESI): Found: 469.1622 (Mþ þ Na), calcd for C13H15O5:
469.1622.
to afford pure 1 (0.044 g, 74%) as a colourless solid. Recrystallization
20
from EtOAc/hexane gave colourless plates, mp 154e155 ꢀC, [
a
]
4.1.7. 5-O-benzyl-7-O-cinnamoyl-5-C-phenyl-a-D-glycero-D-ido-
heptono-1,4-lactone (14)
To a solution of 13 (0.092 g, 0.20 mmol) in dry DMF (2 mL) was
added anhydrous Et3N (0.028 mL, 0.39 mmol) and Meldrum’s acid
(0.057 g, 0.39 mmol). The mixture was stirred at 46e48 ꢀC for 65 h
and then evaporated. Chromatographic purification on a column of
D
þ39.2 (c 0.94, CHCl3), Rf ¼ 0.28 (Et2O); lit. [18] mp 154e156 ꢀC,
20
[
a]
D þ39.5 (c 1.0, CHCl3). IR (KBr): nmax 3410 (OH), 1755 (C]O). 1H
NMR (CDCl3):
d
2.61 (d, 1 H, J2a,2b ¼ 18.7 Hz, H-2a), 2.74 (dd, 1 H,
J2a,2b ¼ 18.7, J2b,3 ¼ 5.6 Hz, H-2b), 4.05 (dd,
1
H, J5,6 ¼ 2.7,
J6,7 ¼ 5.3 Hz, H-6), 4.43 (d, 1 H, J5,6 ¼ 2.7 Hz, H-5), 4.87 (d, 1 H, Hz

V. Popsavin et al. / European Journal of Medicinal Chemistry 45 (2010) 2876e2883
2881
flash silica (7:3 Et2O/hexane) gave pure 14 (0.071 g, 73%), which
stirred for 5 h at 60e70 ꢀC and then evaporated. The residue was
20
crystallized from CH2Cl2/hexane as white fibers, mp 176 ꢀC, [
a]
purified by flash column chromatography (4:1 CH2Cl2/EtOAc) to
D
20
þ86.8 (c 0.5, CHCl3), Rf ¼ 0.23 (7:3 Et2O/hexane). IR (KBr): nmax 1788
afford pure 17 (0.248 g, 69%) as a colourless syrup, [
a]
þ34.5
D
(C]O, lactone), 1713 (C]O, cinnamoyl), 1636 (C]C, cinnamoyl). 1H
(c 1.0, CHCl3), Rf ¼ 0.55 (4:1 CH2Cl2/EtOAc). IR (CHCl3): nmax 3364
NMR (CDCl3):
d
2.57 (d, 1 H, J2a,2b ¼ 18.9 Hz, H-2a), 2.68 (m, 1 H, H-
(OH), 1720 (C]O), 1652 (C]C). 1H NMR (CDCl3):
d
2.68 (bs, 2 H,
2b), 4.37 (d, 1 H, J5,6 ¼ 3.5 Hz, H-5), 4.46 (dd, 1 H, J5,6 ¼ 3.5,
J6,7 ¼ 9.2 Hz, H-6), 4.54 and 4.67 (2 ꢂ d, 2 H, Jgem ¼ 11.6 Hz, PhCH2),
4.96 (m, 2 H, H-3 and0H-4), 6.10 (d, 1 H, J6,7 ¼ 9.2 Hz, H-7), 6.35 (d, 1
exchangeable with D2O, 2 ꢂ OH), 3.76 (s, 3 H, CO2Me), 3.82 (dd, 1 H,
J4,5 ¼ 4.9, J5,6 ¼ 1.6 Hz, H-5), 4.19 (dd, 1 H, J5,6 ¼ 1.6, J6,7 ¼ 8.5 Hz,
H-6), 4.58 (td, 1 H, J2,4 ¼1.7, J3,4 ¼ 4.7, J4,5 ¼ 4.9 Hz, H-4), 4.60 and
4.67 (2 ꢂ d, 2 H, Jgem ¼ 10.9 Hz, PhCH2), 5.99 (d, 1 H, J6,7 ¼ 8.5 Hz,
H-7), 6.20 (dd, 1 H, J2,3 ¼ 15.7, J2,4 ¼1.7 Hz, H-2), 7.08 (dd, 1 H,
J2,3 ¼ 15.7, J3,4 ¼ 4.7 Hz, H-3), 7.23e8.09 (m, 15 H, 3 ꢂ Ph). 13C NMR
0
0
H, J2 ,3 ¼16.1 Hz, H-2 ), 7.19e7.57 (m, 15 H, 3 ꢂ Ph), 7.63 (d, 1 H,
J2 ,3 ¼16.1 Hz, H-3 ). 13C NMR (CDCl3):
d
35.9 (C-2), 72.2 (C-7), 73.0
0
0
0
(PhCH2), 77.4 (C-3), 80.1 (C-5), 82.0 (C-6), 84.6 (C-4), 117.6 (C-20),
127.6, 128.2, 128.3, 128.5, 128.7, 128.9, 130.5, 134.2, 136.4 and 138.0
(3 ꢂ Ph), 145.4 (C-30), 164.9 (C-10), 175.3 (C-1). LRMS (ESI): 509
(Mþ þ K), 493 (Mþ þ Na). Anal. Found: C, 74.03; H, 5.57. Calcd for
C29H26O6: C, 73.84; H, 5.54.
(CDCl3):
d 51.6 (CO2Me), 72.1 (C-4), 73.5 (C-6), 75.0 (PhCH2), 75.6
(C-7), 79.0 (C-5), 121.4 (C-2), 127.5, 128.2, 128.4, 128.5, 129.6, 133.3,
137.0 and 137.4 (3 ꢂ Ph), 146.7 (C-3), 165.1 and 166.7 (2 ꢂ C]O).
HRMS (ESI): Found: 499.1723 (Mþ þ Na), calcd for C28H28NaO7:
499.1727.
4.1.8. (þ)-Crassalactone C (3)
Compound 14 (0.03 g, 0.06 mmol) was refluxed for 30 h with
DDQ (0.073 g, 0.32 mmol) in 10:1 CHCl3/H2O (2 mL). The mixture
was poured to 1% aq NaHCO3 (100 mL) and extracted with CH2Cl2
(3 ꢂ 15 mL). The organic layer was dried and evaporated. The
residue was purified by flash column chromatography (4:1 Et2O/
light petroleum) to afford pure 3 (0.021 g, 87%) as a colourless solid.
4.1.11. Methyl 7-O-benzoyl-2,3-dideoxy-7-C-phenyl-D-gluco-
heptonate (18)
A solution of 17 (0.083 g, 0.17 mmol) in dry MeOH (2 mL) was
hydrogenated over 10% Pd/C (0.036 g) for 4 h at room temperature.
The mixture was filtered and the catalyst washed with EtOH. The
organic solution was evaporated and the residue was purified by
Recrystallization from diethyl ether gave colourless crystals, mp
flash column chromatography (1:1 Et2O/light petroleum) to afford
20
20
153 ꢀC, [
a
]
þ111.6 (c 0.5, EtOH), Rf ¼ 0.46 (1:1 light petroleum/
pure 18 (0.049 g, 72%) as a colourless syrup, [
a
]
þ14.5 (c 0.92,
D
D
30
EtOAc); lit. [23] mp 147e150 ꢀC (EtOH), [
IR (KBr): nmax 3459 (OH), 1784 (C]O, lactone), 1695 (C]O, cinna-
moyl), 1635 (C]C, cinnamoyl). 1H NMR (CDCl3):
2.56 (d, 1 H,
a
]
¼þ98.4 (c 0.5, EtOH).
CHCl3), Rf ¼ 0.43 (Et2O). IR (CHCl3): nmax 3442 (OH), 1721 (C]O). 1H
D
NMR (CDCl3):
d
1.85 (m, 2 H, J2,3 ¼ 7.1, J3,4 ¼ 6.1 Hz, H-3), 2.47 (t, 2 H,
d
J2,3 ¼ 7.1 Hz, H-2), 3.32 (bs, 3 H, exchangeable with D2O, 3 ꢂ OH),
3.63 (m, 1 H, J4,5 ¼ 4.3, J5,6 ¼ 0.9 Hz, H-5), 3.64 (s, 3 H, CO2Me), 3.81
(m, 1 H, J3,4 ¼ 6.1, J4,5 ¼ 4.3 Hz, H-4), 4.11 (dd, 1 H, J5,6 ¼ 0.9,
J6,7 ¼ 8.2 Hz, H-6), 6.03 (d, 1 H, J6,7 ¼ 8.2 Hz, H-7), 7.29e8.16 (m, 10
J2a,2b ¼ 18.6 Hz, H-2a), 2.70 (dd, 1 H, J2a,2b ¼ 18.6, J2b,3 ¼ 5.8 Hz,
H-2b), 4.19 (bs, 1 H, exchangeable with D2O, OH), 4.26 (dd, 1 H,
J6,7 ¼ 9.2, J5,6 ¼ 2.4 Hz, H-6), 4.43 (bs,1 H, H-5), 5.00 (m, 2 H, H-3 and
H-4), 6.00 (d, 1 H, J6,7 ¼ 9.2 Hz, H-7), 6.47 (d, 1 H, J2 ,3 ¼15.9 Hz,
H, 2 ꢂ Ph). 13C NMR (CDCl3):
d 28.4 (C-3), 30.1 (C-2), 51.7 (CO2Me),
0
0
0
H-20), 7.36e7.59 (m, 10 H, 2 ꢂ Ph), 7.78 (d, 1 H, J2 ,3 ¼15.9 Hz, H-3 ).
71.3 (C-5), 72.6 (C-4), 74.7 (C-6), 75.6 (C-7), 127.5, 128.4, 128.5,
128.53, 129.6, 129.7, 133.3 and 137.4 (2 ꢂ Ph),165.6 (PhC]O), 174.62
(CO2Me). HRMS (ESI): Found: 411.1404 (Mþ þ Na), calcd for
C21H24NaO7: 411.1414.
0
0
13C NMR (CDCl3):
d 35.8 (C-2), 72.8 (C-7), 73.1 (C-5), 77.1 (C-3), 82.4
(C-6), 87.0 (C-4), 116.4 (C-20), 127.6, 128.3, 128.6, 128.9, 130.9, 133.6
and 136.6 (2 ꢂ Ph), 147.5 (C-30), 167.5 (C-10), 175.5 (C-1). LRMS (ESI):
m/z 403 (Mþ þ Na), 363 (Mþ þ HꢁH2O).
4.1.12. 2,3-Dideoxy-7-C-phenyl-D-gluco-heptono-1,4-lactone
4.1.9. 5-O-benzoyl-3-O-benzyl-5-C-phenyl-
D-gluco-
(3-deoxycardiobutanolide, 4)
pentofuranose (16)
A solution of 18 (0.035 g, 0.1 mmol) in 0.1 M methanolic NaOMe
(0.2 mL, 0.02 mmol) was stirred for 1 h at room temperature, then
acidified with 2:1 aq. TFA (0.003 mL) and concentrated by co-
distillation with toluene. Flash column chromatography (1:1
CH2Cl2/EtOAc) of the residue gave pure 4 (0.016 g, 69%) as a solid.
A solution of 15 (0.452 g, 0.9 mmol) in 70% aq. AcOH (18 mL) was
stirred for 7 h under reflux. After workup as described above
(Section 4.1.2.), crude sample 16 remained as a yellow syrup. Flash
column chromatography (9:1/4:1 CH2Cl2/EtOAc) of the residue
gave pure 16 (0.296 g, 78%) as a colourless solid. Recrystallization
Recrystallization from CH2Cl2/hexane gave colourless needles, mp
20
20
from CH2Cl2/hexane gave colourless needles, mp 156e157 ꢀC, [
a
]
108e112 ꢀC, [
a
]
D ꢁ11.1 (c 0.44, CHCl3), Rf ¼ 0.34 (EtOAc). IR (KBr):
D
þ29.1/þ33.9 (c 1.27, CHCl3, 72 h), Rf ¼ 0.23 (9:1 CH2Cl2/EtOAc). IR
nmax 3407 (OH), 1760 (C]O). 1H NMR (acetone-d6 þ D2O):
d 1.80
(KBr): nmax 3441 (OH), 1712 (C]O). 1H NMR (CDCl3 þ D2O):
(m, 1 H, H-3a), 2.17e3.36 (m, 1 H, H-3b), 2.39e2.60 (m, 2 H, H-2),
3.67 (dd, 1 H, J5,6 ¼ 2.0, J6,7 ¼ 7.7 Hz, H-6), 3.89 (dd, 1 H, J4,5 ¼ 6.3,
J5,6 ¼ 2.0 Hz, H-5), 4.65 (m, 1 H, J4,5 ¼ 6.3 Hz, H-4), 4.73 (d, 1 H,
J6,7 ¼ 7.7 Hz, H-7), 7.14e7.43 (m, 5 H, Ph). 13C NMR (acetone-d6):
d
4.01e4.18 (m, 3 H, H-2
a
, H-3
a
, H-3
b
and
), 4.23 (d, 1 H, J ¼ 2.8 Hz,
H-2
H-4
b
), 4.33e4.66 (d, 4 H, 2 ꢂ PhCH2
a
b
), 4.68e4.81 (m, 2 H,
), 6.19
),
72.0 and 72.8
), 76.7 (C-2 ), 80.2
), 96.3 (C-1 ), 103.5
), 125.1, 125.2, 125.9, 127.5, 127.7, 128.0, 128.1, 128.3, 128.4,
a
, H-4 ), 5.07 (s, 1 H, H-1
b
b
), 5.39 (d, 1 H, J1,2 ¼ 3.9 Hz, H-1
a
(d, 1 H, J4,5 ¼ 9.6 Hz, H-5
a), 6.20 (d, 1 H, J4,5 ¼ 9.6 Hz, H-5
b
d 24.7 (C-2), 29.0 (C-3), 73.2 (C-5), 74.0 (C-6), 74.5 (C-7), 83.2 (C-4),
7.11e8.04 (m, 30 H, 3 ꢂ Ph). 13C NMR (CDCl3):
d
127.8, 127.84, 128.5 and 143.6 (Ph), 179.0 (C-1). HRMS (ESI): Found:
(2 ꢂ PhCH2), 73.1 (C-5
a
), 73.5 (C-5
b), 74.3 (C-2
a
b
275.0890 (Mþ þ Na), calcd for C13H16NaO5: 275.0890.
(C-4
(C-1
a
b
), 82.7 (C-4
b), 81.2 (C-3
a), 82.4 (C-3
b
a
4.1.13. 3,6-Anhydro-7-O-benzoyl-5-O-benzyl-2-deoxy-7-C-phenyl-
129.6, 129.96, 130.0, 132.99, 133.0, 133.1 133.4, 136.1, 136.9, 138.0
D-glycero-D-ido-heptono-1,4-lactone (19)
and 138.1 (3 ꢂ Ph), 164.62 and 164.76 (PhC]O,
a
and
b
). LRMS (CI):
Procedure A. To a cooled (ꢁ20 ꢀC) and stirred solution of 16
m/z 421 (Mþ þ H). Anal. Found: C, 68.80; H, 5.92. Calcd for
C25H24O6∙H2O: C, 68.48; H, 5.98.
(0.240 g, 0.57 mmol) in dry MeOH (9.6 mL), was added Ph3P]
CHCO2Me (0.385 g, 1.14 mmol) in four equal portions. The mixture
was stirred for 1 h at ꢁ20 ꢀC then for 22 h at room temperature
after which an additional quantity of Ph3P]CHCO2Me (0.292 g,
0.87 mmol) was added. The mixture was stirred for additional 25 h
at room temperature, and then evaporated. The residue was puri-
fied by flash column chromatography (7:3 light petroleum/EtOAc)
4.1.10. Methyl 7-O-benzoyl-5-O-benzyl-2,3-dideoxy-7-C-phenyl-D-
gluco-hept-2-enonate (17)
To a solution of 16 (0.318 g, 0.76 mmol) in dry DMF (6.5 mL) was
added Ph3P]CHCO2Me (0.509 g, 1.52 mmol). The mixture was

2882
V. Popsavin et al. / European Journal of Medicinal Chemistry 45 (2010) 2876e2883
to give 19 (0.132 g, 52%) as a solid. Recrystallization from CH2Cl2/
4.1.16. 1,2-O-cyclohexylidene-5-deoxy-5-C-phenyl-a-D-xylo-
pentofuranose (21)
20
hexane afforded colourless needles, mp 163e165 ꢀC, [
(c 0.91, CHCl3); Rf ¼ 0.46 (7:3 light petroleum/EtOAc).
a]
ꢁ54.2
D
To a stirred solution of 20 (0.659 g, 3.1 mmol) in dry THF
(1.7 mL) was added a 3 M solution of PhMgBr in Et2O (2 mL,
6 mmol). The mixture was stirred under reflux in an atmosphere
of nitrogen for 8.5 h, then quenched with 10% aq. NH4Cl (45 mL)
and extracted with CH2Cl2 (2 ꢂ 30 mL). The combined extracts
were washed with 10% aq NaCl (45 mL), dried and evaporated.
The residue was purified by flash column chromatography (17:3
toluene/EtOAc), to give pure 21 (0.795 g, 85%) as a colourless
Procedure B. Partially protected lactol derivative 16 (0.603 g,
1.43 mmol) and Meldrum’s acid (0.286 g, 1.98 mmol) were dis-
solved in dry DMF (6.5 mL). Dry triethyl amine (0.4 mL, 2.20 mmol)
was added to the reaction mixture and stirred at 46 ꢀC for 65 h. The
volatiles were removed and the residue was purified by flash
column chromatography (9:1 toluene/EtOAc). Pure 19 (0.371 g,
58%) was thus obtained as a solid. Recrystallization from CH2Cl2/
20
hexane gave colourless needles, mp 163e165 ꢀC, [
a
]
ꢁ54.2
solid. Recrystallization from CH2Cl2/hexane gave an analytical
D
20
(c 0.91, CHCl3); Rf ¼ 0.46 (7:3 light petroleum/EtOAc). IR (KBr): nmax
sample 21, mp 119e120 ꢀC, [
a
]
ꢁ2.5 (c 0.5, CHCl3), Rf ¼ 0.23
D
1788 (C]O, lactone), 1721 (PhC]O). 1H NMR (CDCl3):
d
2.58 (d, 1 H,
(1:1 hexane/Et2O). IR (KBr): nmax 3423 (OH). 1H NMR (CDCl3):
1.32e1.74 (m, 10 H, C6H10), 1.85 (d, 1 H, exchangeable with D2O,
J2a,2b ¼ 18.3 Hz, H-2a), 2.70 (dd, 1 H, J2a,2b ¼ 18.3, J2b,3 ¼ 4.6 Hz,
H-2b), 4.34 (d, 1 H, J5,6 ¼ 3.4 Hz, H-5), 4.49 and 4.61 (2 ꢂ d, 2 H,
Jgem ¼ 11.6 Hz, PhCH2), 4.54 (dd, 1 H, J5,6 ¼ 3.4, J6,7 ¼ 9.2 Hz, H-6),
4.93e5.01 (m, 2 H, H-3 and H-4), 6.21 (d, 1 H, J6,7 ¼ 9.2 Hz, H-7),
d
J3,OH ¼ 6.6 Hz, OH-3), 3.00 (dd, 1 H, J5a,5b ¼ 13.6, J4,5a ¼ 8.5 Hz,
H-5a), 3.08 (dd, 1 H, J5a,5b ¼ 13.6, J4,5b ¼ 6.3 Hz, H-5b), 4.00 (d, 1 H,
J3,4 ¼ 2.3 Hz, H-3), 4.40 (ddd,
1
H, J3,4 ¼ 2.3, J4,5a ¼ 8.5,
7.12e8.02 (m, 15 H, 3 ꢂ Ph). 13C NMR (CDCl3):
d
35.9 (C-2), 72.6 (C-
J4,5b ¼ 6.3 Hz, H-4), 4.51 (d, 1 H, J1,2 ¼ 3.9 Hz, H-2), 5.96 (d, 1 H,
7), 73.0 (PhCH2), 77.4 (C-3), 80.2 (C-5), 82.1 (C-6), 84.5 (C-4), 127.5,
128.2, 128.3, 128.4, 128.5, 128.52, 129.6, 129.9, 133.1, 136.2 and 137.9
(3 ꢂ Ph), 164.5 (PhC]O), 175.2 (C-1). LRMS (CI): m/z 445 (Mþ þ H).
Anal. Found: C, 72.41; H, 5.18. Calcd for C27H24O6∙0.2H2O: C, 72.37;
H, 5.49.
J1,2 ¼ 3.9 Hz, H-1), 7.22e7.39 (m, 5 H, Ph). 13C NMR (CDCl3):
d
23.5, 23.8, 24.9, 35.5 and 36.1 (5 ꢂ CH2), 33.9 (C-5), 74.8 (C-3),
81.1 (C-4), 84.7 (C-2), 104.0 (C-1), 112.2 (Cq from C6H10), 126.5,
128.6, 129.2 and 137.5 (Ph). LRMS (ESI): m/z 329 (Mþ þ K), 313
(Mþ þ Na), 291 (Mþ þ H). Anal. Found: C, 67.93; H, 7.42. Calcd for
C17H22O4∙0.5 H2O: C, 68.21; H, 7.72.
4.1.14. 3,6-Anhydro-7-O-benzoyl-2-deoxy-7-C-phenyl-D-glycero-D-
ido-heptono-1,4-lactone (5)
4.1.17. 5-Deoxy-5-C-phenyl-D-xylo-pentofuranose (22)
To a solution of 19 (0.041 g, 0.09 mmol) in EtOAc (2 mL) was
added concetrated HCl (0.02 mL) and 10% Pd/C (0.0164 g). The
suspension was hydrogenated for 44 h at room temperature, then
filtrated through a celite pad and evaporated. Chromatographic
separation on a column of flash silica (7:3 toluene/EtOAc) gave two
A solution of 21 (0.767 g, 2.64 mmol) in 70% aq. AcOH (28 mL)
was stirred for 3 h under reflux. The workup as described above
(Section 4.1.2.) followed by chromatographic separation on
a column of flash silica (3:2 EtOAc/toluene) gave two fractions.
A minor amount of starting compound 21 (0.099 g, 13%) was first
eluted, followed by major product 22 (0.270 g, 49%) isolated as
compounds; eluted first was the major product 5 (0.025 g, 76%) that
20
was isolated as a colourless oil, [
a]
D þ50.0 (c 1.0, CHCl3), Rf ¼ 0.25
a colourless solid. Recrystallization from EtOAc/hexane gave
20
(19:1 CH2Cl2/EtOAc). IR (CHCl3): nmax 3454 (OH), 1787 (C]O,
transparent needles, mp 126e128 ꢀC, [
a
]
þ24.2 / þ16.2
D
lactone), 1722 (PhC]O). 1H NMR (CDCl3):
d
1.30 (bs, 1 H,
(c 0.99, MeOH, 72 h), Rf ¼ 0.49 (EtOAc). IR (KBr): nmax 3410 (OH).
exchangeable with D2O, OH), 2.55 (d, 1 H, J2a,2b ¼ 18.8 Hz, H-2a),
2.67 (dd, 1 H, J2a,2b ¼ 18.8, J2b,3 ¼ 5.1 Hz, H-2b), 4.32 (dd, 1 H,
J5,6 ¼ 2.1, J6,7 ¼ 9.2 Hz, H-6), 4.45 (d, 1 H, J5,6 ¼ 2.1 Hz, H-5),
4.95e5.04 (m, 2 H, H-3 and H-4), 6.12 (d, 1 H, J6,7 ¼ 9.3 Hz, H-7),
1H NMR (Methanol-d4):
3.81e4.8 (m, 3.75 H, H-2, H-3, H-4
5.41 (d, 1 H, J1,2 ¼ 3.8 Hz, H-1
(Methanol-d4): 36.3 and 37.0 (C-5
82.5, 84.4 (C-2, C-3, C-4, both - and
104.2 (C-1
d
2.75e3.13 (m, 2.5 H, 2 ꢂ H-5
a
and
b
b
),
),
a
and ), 5.06 (s, 0.25 H, H-1
b
a
), 7.09e7.37 (m, 6 H, Ph). 13C NMR
d
a
and
b
), 76.8, 77.6, 78.2, 81.4,
-anomers), 97.6 (C-1 ),
7.35e8.14 (m, 10 H, Ph). 13C NMR (CDCl3):
d
35.8 (C-2), 73.1 (C-5),
a
b
a
73.2 (C-7), 77.1 (C-3), 82.5 (C-6), 87.0 (C-4), 127.6, 128.6, 128.7, 128.9,
129.9,133.9 and 136.8 (Ph),166.9 (PhC]O),175.4 (C-1). HRMS (ESI):
Found: 377.0984 (Mþ þ Na), calcd for C20H18NaO6: 377.0996. Eluted
second was pure 6 (0.005 g, 22%) which was isolated as a colourless
b
), 127.1, 129.2, 130.32, 140.1, 140.3 (Ph). HRMS (ESIꢁ):
Found: 209.0812 (MꢁꢁH), calcd for C11H13O4: 209.0819.
Anal. Found: C, 62.44; H, 6.51. Calcd for C11H14O4: C, 62.85;
H, 6.71.
solid. Recrystallization from CH2Cl2/hexane gave needles, mp
20
139 ꢀC, [
a
]
þ49.52 (c 0.62, CHCl3), Rf ¼ 0.24 (4:1 CH2Cl2/EtOAc);
4.1.18. 3,6-Anhydro-2,7-dideoxy-7-C-phenyl-D-gluco-heptono-
1,4-lactone (6)
D
20
lit. [32] mp 101e103 ꢀC, [
HRMS data of 6 see Section 4.1.18.
a
]
D þ37.0 (c 0.14, CHCl3). For IR, NMR and
To a solution of 22 (0.09 g, 0.43 mmol) in dry DMF (0.9 mL) was
added Meldrum’s acid (0.117 g, 0.81 mmol) and dry Et3N (0.12 mL,
0.86 mmol). The mixture was stirred at 46 ꢀC for 48 h and then
evaporated. Chromatographic purification on a column of flash
silica (9:1 CH2Cl2/EtOAc) gave pure 6 (0.052 g, 52%) as a colourless
4.1.15. 3,5-Anhydro-1,2-O-cyclohexylidene-a-D-xylofuranose (20)
To a cooled (0ꢀC) and stirred solution of 7 (0.173 g, 0.75 mmol)
and Ph3P (0.488 g, 1.88 mmol) in dry toluene (2 mL) was added
DEAD (0.3 mL, 1.88 mmol) dropwise over a period of 2e3 min. The
cooling bath was replaced by an oil bath, the mixture was stirred
under reflux for 2.5 h and then evaporated. Flash column chro-
solid. Recrystallization from CH2Cl2/hexane gave an analytical
20
sample 6, mp 139 ꢀC, [
a]
þ49.5 (c 0.62, CHCl3), Rf ¼ 0.24 (4:1
D
20
CH2Cl2/EtOAc); lit. [32] mp 101e103 ꢀC, [
a
]
D þ37.0 (c 0.14, CHCl3).
2.64 (d, 1
matography (iPr2O) of the residue gave pure 20 (0.126 g, 73%) as
IR (KBr): nmax 3438 (OH), 1784 (C]O). 1H NMR (CDCl3):
d
20
a colourless oil, [
EtOAc); lit. [29] [
a
]
þ16.6 (c 0.6, CHCl3), Rf ¼ 0.8 (4:1 toluene/
H, J2a,2b ¼ 18.9 Hz, H-2a), 2.78 (dd, 1 H, J2a,2b ¼ 18.9, J2b,3 ¼ 6.1 Hz,
H-2b), 2.97 (dd, 1 H, J7a,7b ¼ 13.6, J6,7a ¼ 7.3 Hz, H-7a), 3.04 (dd, 1 H,
J7a,7b ¼ 13.6, J6,7b ¼ 6.8 Hz, H-7b), 4.15e4.25 (m, 2 H, H-5 and H-6),
4.90 (d, 1 H, J3,4 ¼ 4.7 Hz, H-4), 5.02 (dd, 1 H, J2b,3 ¼ 6.1, J3,4 ¼ 4.7 Hz,
2D0
a
]
þ17.4 (c 0.66, CHCl3). 1H NMR (CDCl3):
D
d
1.30e1.71 (m, 10 H, C6H10), 4.15 (ddd, 1 H, J5a,5b ¼ 7.6 Hz,
J3,5a ¼ 0.5 Hz, J4,5a ¼ 2.4 Hz, H-5a), 4.59e4.70 (m, 2 H, J1,2 ¼ 3.6 Hz,
J4,5b ¼ 4.1 Hz, H-2 and H-5b), 5.01 (m, 1 H, H-4), 5.1 (d, 1 H,
J3,4 ¼ 4.0 Hz, H-3), 6.18 (d, 1 H, J1,2 ¼ 3.6 Hz, H-1). 13C NMR (CDCl3):
H-3), 7.19e7.40 (m, 5 H, Ph). 13C NMR (CDCl3):
d 34.2 (C-7), 35.8
(C-2), 74.1 (C-5), 76.1 (C-3), 81.4 (C-6), 87.6 (C-4), 126.7, 128.5, 129.0
and 137.2 (Ph), 175.6 (C-1). LRMS (CI): m/z 469 (2Mþ þ H), 235
(Mþ þ H). HRMS (ESI): Found: 235.0954 (Mþ þ H), calcd for
C13H15O4: 235.0965.
d
23.3, 23.5, 24.5, 36.2 and 37.1 (C6H10), 77.9 (C-4), 78.0 (C-5), 83.9
(C-2), 87.3 (C-3), 107.5 (C-1), 114.0 (Cq from C6H10). LRMS (CI): m/z
212 (Mþ).

V. Popsavin et al. / European Journal of Medicinal Chemistry 45 (2010) 2876e2883
2883
[10] L. Hernández-García, L. Quintero, H. Höpfl, M. Sosa, F. Sartillo-Piscil, Tetrahe-
dron 65 (2009) 139e144.
4.2. In vitro antitumour assay
[11] K.R. Prasad, S.L. Gholap, J. Org. Chem. 73 (2008) 2e11.
[12] P. Kapitán, T. Gracza, Tetrahedron: Asymmetry 19 (2008) 38e44.
[13] K.R. Prasad, M.G. Dhaware, Synthesis (2007) 3697e3705.
[14] V.K. Yadav, D. Agrawal, Chem. Commun. (2007) 232e5234.
[15] C. Sartillo-Melendez, S. Cruz-Gregorio, L. Quintero, F. Sartillo-Piscil, Lett. Org.
Chem. 3 (2006) 504e509.
[16] M.D. Mihovilovic, D.A. Bianchi, F. Rudroff, Chem. Commun. (2006)
3214e3216.
[17] R. Fernández de la Pradilla, J. Fernández, A. Viso, J. Fernández, A. Gómez,
Heterocycles 68 (2006) 1579e1584.
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
5 ꢂ103 (HeLa and MRC-5) cells per well to assure logarithmic
growth rate throughout the assay period. Antiproliferative activity
was evaluated by the tetrazolium colorimetric MTT assay, after
exposure of cells to the tested compounds for 72 h, following the
recently reported procedure [34].
[18] P. Ruiz, J. Murga, M. Carda, J.A. Marco, J. Org, Chem. 70 (2005) 713e716.
ꢀ
ꢀ
ꢀ
[19] V. Popsavin, G. Benedekovic, B. Sreco, M. Popsavin, J. Francuz, V. Kojic,
ꢀ
G. Bogdanovic, Bioorg. Med. Chem. Lett. 18 (2008) 5178e5181.
Acknowledgement
ꢀ
ꢀ
ꢀ
[20] V. Popsavin, G. Benedekovic, B. Sreco, M. Popsavin, J. Francuz, V. Kojic,
ꢀ
G. Bogdanovic, Org. Lett. 9 (2007) 4235e4238.
ꢀ
ꢀ
ꢀ
[21] V. Popsavin, G. Benedekovic, B. Sreco, J. Francuz, M. Popsavin, V. Kojic,
This work was supported by a research grant from the Ministry
of Science and Technological Development of the Republic of Serbia
(Project No. 142005).
ꢀ
ꢀ
G. Bogdanovic, V. Divjakovic, Tetrahedron 65 (2009) 10596e10607.
[22] A. Hisham, M. Toubi, W. Shuaily, M.D.A. Bai, Y. Fujimoto, Phytochemistry 62
(2003) 597e600.
[23] P. Tuchinda, B. Munyoo, M. Pohmakotr, P. Thinapong, S. Sophasan, T. Santisuk,
V. Reutrakul, J. Nat. Prod. 69 (2006) 1728e1733.
References
ꢀ
ꢀ
[24] M. Popsavin, V. Popsavin, N. Vukojevic, D. Miljkovic, Collect. Czech. Chem.
Commun. 59 (1994) 1884e1888.
[25] K.R.C. Prakash, S. Prahlada Rao, Tetrahedron 49 (1993) 1505e1510.
[26] A.S. Ivanov, Chem. Soc. Rev. 37 (2008) 789e811.
[27] N. Ikemoto, S.L. Schreiber, J. Am. Chem. Soc. 114 (1992) 2524e2536.
[1] C. Wiart, Evid.-based Complement. Altern. Med. 4 (2007) 299e311.
[2] M.A. Blazquez, A. Bermejo, M.C. Zafra-Polo, D. Cortes, Phytochem. Anal. 10
(1999) 161e170.
[3] X.P. Fang, J.E. Anderson, C.J. Chang, P.E. Fanwick, J.L. McLaughlin, J. Chem. Soc.
Perkin. Trans. 1 (1990) 1655e1661.
ꢁ
ꢀ
ꢀ
ꢀ
[28] V. Popsavin, S. Grabez, M. Popsavin, I. Krstic, V. Kojic, G. Bogdanovic,
ꢀ
V. Divjakovic, Tetrahedron. Lett. 45 (2004) 9409e9413.
[29] P. Hadzic, N. Vukojevic, M. Popsavin, J. Canadi, J. Serb, Chem. Soc. 66 (2001)
1e8.
ꢁ
ꢁ ꢀ
ꢀ
[4] X.P. Fang, J.E. Anderson, C.J. Chang, J.L. McLaughlin, P.E. Fanwick, J. Nat. Prod. 54
(1991) 1034e1043.
[30] K.C. Kumara Swamy, N.N. Bhuvan Kumar, E. Balaraman, K.V.P. Pavan Kumar,
Chem. Rev. 109 (2009) 2551e2651.
[5] X.P. Fang, J.E. Anderson, C.J. Chang, J.L. McLaughlin, Tetrahedron 47 (1991)
9751e9758.
[31] T.Y.S. But, P.H. Toy, Chem. Asian J. 2 (2007) 1340e1355.
[32] P.J. Murphy, S.T. Dennison, Tetrahedron 49 (1993) 6695e6700.
[33] S. Henkel, T. Gracza, V. Jager, Z. Kristallogr. 212 (1997) 423e424.
[6] A. de Fatima, L.V. Modolo, L.S. Conegero, R.A. Pilli, C.V. Ferreira, L.K. Kohn, J.E. de
Carvalho, Curr. Med. Chem. 13 (2006) 3371e3384.
[7] H.B. Mereyala, M. Joe, Curr. Med. Chem. Anti-Cancer Agents 1 (2001) 293e300.
[8] M. Mondon, J.-P. Gesson, Curr. Org. Synth. 3 (2006) 41e75.
[9] G. Zhao, B. Wu, X.Y. Wu, Y.Z. Zhang, Mini-Rev. Org. Chem. 2 (2005) 546e564.
ꢀ
ꢀ
ꢀ
ꢀ
[34] V. Popsavin, B. Sreco, I. Krstic, M. Popsavin, V. Kojic, G. Bogdanovic, Eur. J. Med.
Chem. 41 (2006) 1217e1222.