Stereoselective synthesis of jaspine B from d-xylose

Article abstract of DOI:10.1016/j.carres.2006.08.011

The natural cytotoxic marine compound, jaspine B, is stereoselectively synthesized from d-xylose in 11 linear steps with a 23.9% overall yield. The key step in the synthesis involves an iodine-induced debenzylation of a primary alcohol and the subsequent

Full text of DOI:10.1016/j.carres.2006.08.011

Carbohydrate Research 341 (2006) 2653–2657
Stereoselective synthesis of jaspine B from D-xylose
Jun Liu,a Yuguo Du,a,* Xiaomin Dong,b Shucong Meng,b Junjun Xiaob and Lijian Chengc
aState Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences,
Chinese Academy of Sciences, Beijing 100085, China
bDepartment of Cell Biology, Basic Medicinal College, Peking University Health Science Center, Beijing 100083, China
cSchool of Chemical and Environmental Engineering, China University of Mining and Technology-Beijing, Beijing 100083, China
Received 25 June 2006; received in revised form 7 August 2006; accepted 10 August 2006
Available online 14 September 2006
Abstract—The natural cytotoxic marine compound, jaspine B, is stereoselectively synthesized from D-xylose in 11 linear steps with a
23.9% overall yield. The key step in the synthesis involves an iodine-induced debenzylation of a primary alcohol and the subsequent
2,5-cyclization to fit the required configuration of jaspine B. A preliminary bioassay shows strong inhibition activities against human
MDA231, Hela, and CNE cell lines, indicating potential usage in various cancer treatments.
ꢀ 2006 Elsevier Ltd. All rights reserved.
Keywords: Natural products; Jaspine B; Antitumor activity; Carbohydrates; Total synthesis
1. Introduction
novel structural features have encouraged several
research groups to explore the preparation of this com-
pound.7 To improve our understanding of this anhydro-
sphingosine and its targeting to tumor cells and to lay
the groundwork for more potent analogues based on
this novel structure, we launched a stereoselective total
synthesis of natural jaspine B. We report herein a prac-
tical synthesis of jaspine B using D-xylose as the chiral
starting material, and a preliminary bioassay against
human MDA231, Hela, and CNE cell lines.
Phytosphingosine is involved in several biological
processes, including heat–stress response and endocytic
events.1 Further studies revealed that sphingosine 1-
phosphate induces a rapid and relevant release of ara-
chidonic acid, and increases phospholipase D activity
in A549 cells.2 Phytosphingosine is also found to be a
key intermediate from which more complex metabolites
are derived.3 Apart from the linear structures, phyto-
sphingosine derivatives also exist as anhydro forms that
were shown to be potent inhibitors of a variety of glyco-
sidase activities.4 Jaspine B (1, Scheme 1), one of the
natural occurring anhydrophytosphingosine derivatives,
was isolated from marine sponges, Pachastrissa sp. and
Jaspis sp.,5 and exhibited a significant cytotoxicity
against P388, A549, HT29, and MEL28 carcinoma cell
lines in vitro.6 High-resolution NMR and mass spectral
analyses, as well as chemical derivatization studies
suggested an all-syn trisubstituted tetrahydrofuran
framework, and the (2S,3S,4S) absolute configuration
of jaspine B. The impressive biological activity and
2. Results and discussion
We have previously accomplished the total synthesis of
jaspine B.7d To provide more samples for bioactivity
research, we enlarged the reaction scale (10 g) and
unexpectedly found that the conversion of mesylate into
azido intermediate in the presence of C-1 diethylacetal
group was quite slow. To explore a more practical
method toward jaspine B preparation, we designed the
following strategy as shown in Scheme 1.
3,5-Di-O-benzyl-a-D-xylofuranose (3) was easily ob-
tained from D-xylose (2) through a three-step reaction
in a 72% overall yield.8 Oxidation of diol 3 with NaIO4
*
Corresponding author. Tel.: +86 10 62914475; fax: +86 10
62923563; e-mail: duyuguo@rcees.ac.cn
0008-6215/$ - see front matter ꢀ 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2006.08.011

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J. Liu et al. / Carbohydrate Research 341 (2006) 2653–2657
BnO
OH
BnO
O
O
BnO
OH
CHO
OH
D-Xylose
OBn
a
b
OBn
2
4
OH
BnO
OH
3
O
O
OH
CHO
CH2I
c
d
BnO
g
e
OBn
7 R= OH
OBn
RO
HO
OBn
6
5
f
8
R= Ms
O
O
O
CH=CHC12H25
CH=CHC12H25
C(CH2)12CH3
i
h
OBn
OBn
MsO
OH
1
(jaspine B)
N3
H2N
10
9
Scheme 1. Total synthesis of jaspine B. Reagents and conditions: (a) Ref. 8, 72% in three steps; (b) NaIO4, MeOH, H2O; (c) CH3Ph3P+Brꢀ, BuLi,
dry THF, ꢀ40 ꢁC to rt, 82% for two steps; (d) I2, NaHCO3, CH3CN, 80%; (e) NaHCO3, dry DMSO, 150 ꢁC, 6 min; (f) MsCl, Py, rt, 30 min, 74% for
two steps; (g) C13H27Ph3P+Brꢀ, BuLi, dry THF, ꢀ40 ꢁC to rt, 90%, Z/E ratio >10/1; (h) NaN3, NH4Cl, DMF, 120 ꢁC, 20 h, 80%; (i) Pd/C, H2,
MeOH, TFA, 5 h, 95%.
in methanol9 gave (2S,3R)-2,4-bis(benzyloxy)-3-hydr-
oxybutanal (4), which was directly subjected to a Wittig
reaction with Ph3P@CH2 and gave (2R,3R)-1,3-di-O-
benzyl-4-pentene-1,2,3-triol (5) in an 82% yield (Scheme
1). An iodine-induced consecutive cyclization/benzyl
deprotection was carried out smoothly in anhyd aceto-
nitrile in the presence of I2 and NaHCO3,10 affording
side chain. The SN2 substitution of 9 with NaN3 in
DMF gave (2S,3S,4S)-4-azido-3-(benzyloxy)-2-((E,Z)-
tetradec-1-enyl)tetrahydrofuran (10) in an 80% yield.
A single step hydrogenation of the azido and benzyl
groups, and the side-chain double bond in methanol
(containing 1% TFA) furnished target molecule, jaspine
B (1), in a salt form in an excellent yield of 95%.
The effects of jaspine B against human MDA231,
CNE, and Hela cell growth were investigated based on
Higa’s method.6a Jaspine B significantly inhibited the
proliferation of human MDA231 cell lines with IC50
0.52, 0.37, and 0.1 lg/mL corresponding to the treat-
ments of 24, 48, and 72 h, respectively. For human
CNE cell lines, the IC50s were 0.78 and 0.005 lg/mL
corresponding to 48 and 72 h, while human Hela cell
lines had an IC50 0.79 lg/mL at 72 h. The results are
summarized in Table 1.
iodide
6 (80%), which was further transformed
into (2R,3S,4R)-3-(benzyloxy)-4-hydroxytetrahydrofuran-
2-carbaldehyde (7) with dimethyl sulfoxide.11 On treat-
ment of crude 7 with methanesulfonyl chloride in pyri-
dine we obtained (2R,3S,4R)-3-(benzyloxy)-4-methane-
sulfonyloxytetrahydrofuran-2-carbaldehyde (8) in
a
74% isolated yield. The standard Wittig olefination of
8 with a C-13 alkyl donor resulted in the incorporation
of an inseparable mixture of (3R,4R,5S)-4-(benzyloxy)-
5-((E,Z)-tetradec-1-enyl)tetrahydrofuran-3-yl methane-
sulfonate (9, 90% yield) with the corresponding C-14
olefinic side chain. The Z/E ratio was determined to
In conclusion, utilizing a chiral-pool strategy based on
D-xylose as the starting material, the stereoselective total
synthesis of a structurally unique bioactive anhydro-
sphingosine natural product, jaspine B, has been
1
be greater than 10:1 based on H NMR spectroscopy,
but both could be further reduced to the desired alkyl
Table 1. Effect (inhibition rate, %) of jaspine B on the growth of human MDA231, CNE, and HeLa cells
Groups
Dose (lg/mL)
MDA231
48 h
Hela
48 h
CNE
48 h
24 h
72 h
24 h
72 h
24 h
72 h
Jaspine B
0.005
0.01
0.1
1
3
0
16
12
35
67
35
0
26
35
32
93
28
0
37
44
51
95
32
0
4
0
20
45
27
0
0
17
27
35
15
0
42
45
42
52
59
0
0
0
0
43
0
0
0
19
23
59
37
0
49
69
73
86
68
0
CDDP
Control

J. Liu et al. / Carbohydrate Research 341 (2006) 2653–2657
2655
achieved in 11 linear steps and a 23.9% overall yield. The
key step in the synthesis involves an iodine-induced
debenzylation on primary alcohol and the subsequent
2,5-cyclization to fit the required configuration toward
jaspine B. A preliminary bioassay shows that jaspine B
presents strong inhibition activities against human
MDA231, Hela, and CNE cell lines, indicating potential
usage in various cancer treatments. The current report
provides an alternative way for the preparation of the
antitumor agent jaspine B, and the method should be
valuable in the preparation of other tetrahydrofuran
derivatives.12
ether–EtOAc) until all starting materials disappeared.
The reaction was quenched by satd NH4Cl (0.2 mL),
then diluted with water and extracted with EtOAc
(3 · 20 mL). The combined organic phase was dried
over anhyd Na2SO4 and concentrated to dryness. Purifi-
cation of the residue by silica gel column chromatogra-
phy (3:1 petroleum ether–EtOAc) gave 5 (489 mg, 82%
for two steps) as a syrup: ½aꢁD ꢀ21 (c 1, CHCl3); H
NMR (400 MHz, CDCl3): d 2.70 (d, 1H, J 3.9 Hz),
3.50 (dd, 1H, J 5.5, 10.0 Hz), 3.58 (dd, 1H, J 3.9,
10.0 Hz), 3.76–3.80 (m, 1H), 3.92 (t, 1H, J 6.7 Hz),
4.36, 4.63 (2d, 2H, J = 11.6 Hz), 4.50, 4.55 (2d, 2H,
J = 12.0 Hz), 5.32–5.36 (m, 2H), 5.74–5.83 (m, 1H),
7.25–7.36 (m, 10H). Anal. Calcd for C19H22O3: C,
76.48; H, 7.43. Found: C, 76.81; H, 7.36.
25
1
3. Experimental
3.1. General methods
3.3. (2R,3S,4R)-3-Benzyloxy-2-(iodomethyl)tetrahydro-
furan-4-ol (6)
Optical rotations were determined at 25 ꢁC with a Per-
kin–Elmer Model 241-Mc automatic polarimeter, and
[a]D-values are in units of 10ꢀ1 deg cm2 gꢀ1. The 1H
and 13C NMR spectra were recorded with a Bruker
ARX 400 spectrometer for solutions in CDCl3 or
CD3OD. Chemical shifts are given in parts per million
downfield from internal Me4Si. Mass spectra were mea-
sured using a JEOL JMS-700 mass spectrometer. Thin-
layer chromatography (TLC) was performed on silica
gel HF254 with detection by charring with 30% (v/v)
H2SO4 in MeOH, or in some cases by a UV lamp. Col-
umn chromatography was conducted by elution of a col-
umn of silica gel (100–200 mesh) with EtOAc–petroleum
ether (60–90 ꢁC) as the eluent. Solutions were concen-
trated at <60 ꢁC under reduced pressure.
To a solution of 5 (220 mg, 0.74 mmol) in anhyd
CH3CN (10 mL) was added NaHCO3 (186 mg,
2.2 mmol). The mixture was stirred at 0 ꢁC for 5 min,
and then iodine (560 mg, 2.2 mmol) was added. The
reaction was monitored by TLC (2:1 petroleum ether–
EtOAc). After completion, the mixture was diluted with
EtOAc and washed with aq sodium thiosulfate. The
combined organic phase was dried over anhyd Na2SO4
and concentrated under vacuum to give a diastereomeric
mixtrue. Purification of the mixtures by silica gel column
chromatography (2:1 petroleum ether–EtOAc) gave
25
pure compound 6 (197 mg, 80%) as a syrup: ½aꢁD +78
1
(c 1, CHCl3); H NMR (400 MHz, CDCl3): d 1.65 (br
s, 1H), 3.28 (dd, 1H, J 6.0, 9.3 Hz), 3.36 (t, 1H, J
9.3 Hz), 3.82 (d, 1H, J 9.9 Hz), 4.00 (d, 1H, J 3.7 Hz),
4.20 (dd, 1H, J 3.9, 9.9 Hz), 4.39–4.44 (m, 2H), 4.62,
4.67 (2d, 2H, J 11.4 Hz), 7.32–7.37 (m, 5H). Anal. Calcd
for C12H15IO3: C, 43.13; H, 4.52. Found C, 43.31; H,
4.42.
3.2. (2R,3R)-1,3-Di-O-benzyl-4-pentene-1,2,3-triol (5)
To a solution of compound 3 (660 mg, 2 mmol) in
MeOH (10 mL) was added NaIO4 (642 mg in 5 mL
H2O, 3 mmol). The mixture was stirred at room temper-
ature and monitored by TLC (2:1 petroleum ether–
EtOAc) until all starting materials disappeared. The
mixture was then filtered, and the filtrate was extracted
with CH2Cl2 (2 · 15 mL). The combined organic phase
was dried over anhyd Na2SO4 and concentrated to give
3.4. (2R,3S,4R)-3-(Benzyloxy)-4-hydroxytetrahydro-
furan-2-carbaldehyde (7)
To a mixture of DMSO (5 mL) and NaHCO3 (400 mg)
at 150 ꢁC under N2 protection was added compound 6
(170 mg, 0.51 mmol). The mixture was stirred at
150 ꢁC for 5 min, and then rapidly cooled to room tem-
perature. The mixture was poured into ice water and
extracted with Et2O (3 · 10 mL). The combined organic
phase was dried over anhyd Na2SO4 and concentrated
to dryness. Purification of the residue by silica gel col-
umn chromatography (2:1 petroleum ether–EtOAc)
gave aldehyde 7, which was directly used in the next step
without further purification. A small sample was puri-
fied on a silica gel column to provide analytically pure
syrupy
(2S,3R)-2,4-bis(benzyloxy)-3-hydroxybutanal
(4), which was directly used for the next reaction with-
out purification. To a pre-cooled (ꢀ40 ꢁC) solution of
Wittig salt CH3Ph3P+Brꢀ (1.07 g, 3 mmol) in THF
(25 mL) was slowly added n-BuLi (2.5 M in hexane,
2 mL, 5 mmol) under N2 protection. The orange mixture
was stirred under these conditions for about 20 min,
then a solution of the above 4 in dry THF (5 mL) was
added dropwise under N2 protection. The mixture was
stirred at this temperature for another 30 min, then
allowed to warm up to room temperature. The progress
of the reaction was monitored by TLC (2:1 petroleum
25
1
7: ½aꢁD +64 (c 1, CHCl3); H NMR (400 MHz, CDCl3):
d 1.80 (br s, 1H), 3.95 (d, 1H, J 10.0 Hz), 4.28–4.31 (m,

2656
J. Liu et al. / Carbohydrate Research 341 (2006) 2653–2657
2H), 4.41 (d, 1H, J 3.3 Hz), 4.51 (dd, J 1.7, 4.9 Hz), 4.53,
4.60 (2d, 2H, J 11.9 Hz), 7.25–7.37 (m, 5H), 9.58 (d, 1H,
J 1.8 Hz). 13C NMR (100 MHz, CDCl3): d 72.5, 74.4,
75.0, 84.6, 85.9, 127.6, 127.9, 128.4, 136.9, 201.0.
HRFABMS: Calcd for C12H14O4: 222.0892. Found:
223.0878 (M+H)+.
82.6, 82.9, 123.3, 127.7, 127.9, 128.4, 135.7, 137.2. Anal.
Calcd for C26H42O5S: C, 66.92; H, 9.07. Found: C,
67.15; H, 8.98.
3.7. (2S,3S,4S)-4-Azido-3-(benzyloxy)-2-((E,Z)-tetradec-
1-enyl)tetrahydrofuran (10)
3.5. (2R,3S,4R)-3-(Benzyloxy)-4-methanesulfonyloxy-
tetrahydrofuran-2-carbaldehyde (8)
To a solution of 9 (47 mg, 0.1 mmol, Z, E mixture) in
dry DMF (5 mL) was added NaN3 (39 mg, 0.6 mmol)
and anhyd NH4Cl (107 mg, 0.2 mmol). The mixture
was heated to 120 ꢁC and stirred for about 20 h in a
dark room. The reaction was monitored by TLC (4:1
petroleum ether–EtOAc) until all starting materials dis-
appeared, then the mixture was diluted with water and
extracted with EtOAc (4 · 8 mL). The organic phase
was dried over anhyd Na2SO4 and concentrated. Purifi-
cation of the residue by silica gel column chromatogra-
phy (4:1 petroleum ether–EtOAc) gave 10 (33 mg, 80%,
To a solution of crude 7 (0.51 mmol) in pyridine (2 mL)
was added methanesulfonyl chloride (90 lL, 1.2 mmol).
The mixture was stirred at room temperature for 30 min,
and then co-evaporated with toluene under vacuum.
Purification of the residue by silica gel column chroma-
tography (1:1 petroleum ether–EtOAc) gave 8 (113 mg,
25
74% for two steps) as a syrup: ½aꢁD +27 (c 0.4, CHCl3);
1H NMR (400 MHz, CDCl3): d 2.94 (s, 3H), 4.10 (d, 1H,
J 11.1 Hz), 4.28 (dd, 1H, J 3.5, 11.1 Hz), 4.44 (d, 1H, J
4.6 Hz), 4.50, 4.60 (2d, 2H, J 11.9 Hz), 4.57 (d, 1H, J
4.9 Hz), 5.12 (d, 1H, J 3.1 Hz), 7.21–7.31 (m, 5H), 9.53
(s, 1H). 13C NMR (100 MHz, CDCl3): d 37.9, 71.8,
72.2, 80.6, 82.9, 83.9, 127.5, 127.9, 128.2, 136.1, 198.7.
HRFABMS: Calcd for C13H16O6S: 300.0668; Found:
301.0685 (M+H)+.
1
Z, E mixture) as a syrup: Selected H NMR (400 MHz,
CDCl3) for the Z isomer: d 0.88 (t, 3H, J 7.1 Hz), 1.20
(br s, 20H), 2.07–2.09 (m, 2H), 3.88–3.97 (m, 3H), 4.11
(t, 1H, J 5.0 Hz), 4.62, 4.70 (2d, 2H, J 11.8 Hz), 4.71–
4.72 (m, 1H), 5.65–5.73 (m, 2H, J 11.0 Hz), 7.29–7.37
(m, 5H). 13C NMR (100 MHz, CDCl3): d 14.0, 22.6,
27.7, 29.2, 29.3, 29.4, 29.5, 29.6, 31.8, 61.5, 68.6, 73.3,
75.8, 80.4, 124.9, 127.7, 127.8, 128.3, 135.0, 137.4.
HRFABMS: Calcd for C25H39N3O2: 413.3042. Found:
414.3068 (M+H)+.
3.6. (3R,4R,5S)-4-(Benzyloxy)-5-((E,Z)-tetradec-1-enyl)-
tetrahydrofuran-3-yl methanesulfonate (9)
To a pre-cooled (ꢀ40 ꢁC) solution of the Wittig salt
C13H27Ph3P+Brꢀ (884 mg, 1.68 mmol) in anhyd THF
(25 mL) was slowly added n-BuLi (2.5 M in hexane,
0.67 mL, 1.68 mmol) under N2 protection. The orange
solution was stirred under these conditions for about
20 min, and then a solution of 8 (336 mg, 1.12 mmol)
in dry THF (3 mL) was added dropwise under N2 pro-
tection. The mixture was stirred at this temperature
for another 30 min, and then allowed to warm up to
room temperature. The reaction was monitored by
TLC (3:1 petroleum ether–EtOAc) until all starting
materials disappeared. The reaction was then quenched
by satd NH4Cl (0.2 mL), and the mixture was diluted
with water and extracted with EtOAc (3 · 20 mL). The
combined organic phase was dried over anhyd Na2SO4
and concentrated to dryness. Purification of the residue
by silica gel column chromatography (3:1 petroleum
ether–EtOAc) gave 9 (470 mg, 90%, Z/E >10:1, deter-
mined by 1H NMR) as a syrup: Selected 1H NMR
(400 MHz, CDCl3) for the Z-isomer: d 0.88 (t, 3H, J
7.1 Hz), 1.27 (br s, 20H), 2.07–2.13 (m, 2H), 2.99 (s,
3H), 3.98 (dd, 1H, J 1.9, 10.9 Hz), 4.08 (d, 1H, J
3.9 Hz), 4.29 (dd, 1H, J 4.9, 10.9 Hz), 4.64 (2d, 2H, J
12.1 Hz), 4.77 (dd, 1H, J 3.9, 8.3 Hz), 5.16 (d, 1H, J
4.7 Hz), 5.63–5.77 (m, 2H), 7.29–7.35 (m, 5H). 13C
NMR (100 MHz, CDCl3): d 14.0, 22.6, 27.9, 29.1,
29.2, 29.3, 29.4, 29.5, 29.6, 31.8, 38.3, 70.5, 72.3, 76.0,
3.8. Synthesis of jaspine B (1)
To a mixture of olefin 10 (210 mg, 0.5 mmol) and Pd/C
(10% content, 50 mg) in MeOH (50 mL, containing 1%
of TFA) H2 was bubbled in at a flow rate of 100 mL/
min under room temperature and 4 atm pressure.
(Caution! Extreme fire hazard!) The hydrogenation
was kept at these conditions for about 5 h, at the end
of which time, TLC (4:1 EtOAc–MeOH) showed only
one product generated. The Pd/C was filtered, and the
filtrate was concentrated. The residue was purified on
a short silica gel column using 4:1 EtOAc–MeOH as
eluent to furnish target compound 1 (145 mg, 95%) as
a white solid in salt form: ½aꢁD +11 (c 1, CHCl3); H
NMR (400 MHz, CD3OD): d 0.89 (t, 3H, J 7.0 Hz),
1.26–1.45 (m, 24H), 1.60–1.65 (m, 2H), 3.70 (dt, 1H,
J 3.5, 6.8 Hz), 3.79 (dd, 1H, J 4.8, 7.9 Hz), 3.82–3.93
(m, 2H), 4.23 (dd, 1H, J 3.5, 4.8 Hz). 13C NMR
(100 MHz, CD3OD): d 14.5, 23.7, 27.2, 29.7, 30.5,
30.7, 30.8, 30.9, 33.1, 54.3, 68.9, 70.9, 84.4. HRFABMS:
Calcd for C18H37NO2 (after co-evaporation with
NH4OH): 299.2824. Found: 300.2856 (M+H)+.
25
1
3.9. Bioassay
Human MDA231, CNE, and HeLa cells (3 · 105/well)
were cultured in a suspension of Dulbcco’s Modified

J. Liu et al. / Carbohydrate Research 341 (2006) 2653–2657
2657
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born calf serum, 100 kU/mL of penicillin and 100 mg/
mL of streptomycin in a humidified atmosphere of 5%
CO2 at 37 ꢁC. Exponentially growing tumor cells at
1 · 105 cells/mL in culture were treated with jaspine B
at a concentration of 0.005, 0.01, 0.1, and 1 lg/L for
24, 48, and 72 h, respectively. The positive control
cultures were treated with CDDP at 3 lg/mL under
the same conditions, while the negative control cultures
(DMEM) were left untreated at 37 ꢁC for the same
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Acknowledgments
This work was supported by the National Basic
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Supplementary data
Supplementary data (images of NMR spectra for com-
pounds) associated with this article can be found, in
the online version, at doi:10.1016/j.carres.2006.08.011.
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