A mild, efficient, and selective procedure for transprotection of acetonides to acetates catalyzed with HClO4-SiO2

Article abstract of DOI:10.1016/j.carres.2009.08.035

The transformation of acetonides into acetates is frequently required in synthetic chemistry. An efficient procedure for direct conversion of acetonides into acetates in the presence of HClO₄-SiO₂ under mild conditions was developed.

Full text of DOI:10.1016/j.carres.2009.08.035

Carbohydrate Research 344 (2009) 2342–2348
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Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
A mild, efficient, and selective procedure for transprotection of acetonides
to acetates catalyzed with HClO4–SiO2
b
a
a
a
a
Hai-Xia Liu a, Qin-Pei Wu a, , Yi-Nan Shu , Xi Chen , Xiao-Dong Xi , Ti-Jian Du , Qing-Shan Zhang
*
a Department of Applied Chemistry and Pharmacy, Beijing Institute of Technology, Beijing 100081, China
b School of Life Science and Technology, Beijing Institute of Technology, Beijing 100081, China
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 11 March 2009
Received in revised form 24 July 2009
Accepted 27 August 2009
Available online 2 September 2009
The transformation of acetonides into acetates is frequently required in synthetic chemistry. An efficient
procedure for direct conversion of acetonides into acetates in the presence of HClO4–SiO2 under mild con-
ditions was developed. The acetonides of primary hydroxy groups are directly converted to diacetates,
and the anomeric acetonides of furanosides are stereoselectively transformed into the corresponding
acetyl b-D-furanosides with a 2-acetoxyisopropyl group.
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Acetals
Esterification
Esters
Heterogeneous catalysis
Protecting groups
1. Introduction
dene-a-D-xylofuranose (2, Scheme 1) in large scale during the
course of our studies in the synthesis of nucleoside mimetics, we
found that HClO4–SiO2 (0.5 mmol/g) is an extremely efficient sub-
stitute for Bi(OTf)3ꢀxH2O25 and is readily removed and recovered
via filtration after the reaction is complete.37
Both acetonides and acetates are most frequently used as pro-
tecting groups in synthetic chemistry because they are readily
introduced and removed,1–3 particularly, in carbohydrate,4–9 nucle-
oside,10–13 and polyhydroxy compound chemistries.14–16 In view the
fact that the transformation of acetonides into corresponding diace-
tates is often required in organic synthesis due to the complemen-
tary stability of these two kinds of protecting groups,17–24 studies
in this transformation, here termed ‘transprotection’, are consider-
ably worthy in spite of the limited methods that are currently
available.25
We herein wish to report an effective method for transprotec-
tion of isopropylidene acetals into acetates by making use of a
cheaper, non-toxic, and reusable catalyst reported by Chakraborti
and Gulhane,26 namely, HClO4–SiO2 (Scheme 1), which has been
used to catalyze a wide range of transformations such as the for-
mation of acetals,27–29 thioacetals,30 and acylal,31,32 acetylation of
carbohydrates,33–35 glycosylation,36,37 synthesis of quinoxalines,38
thio-Michael addition,39 and N-Boc formation.40
Treatment of 1 (0.15 mol) with Ac2O (5 equiv) in CH2Cl2 at rt in
the presence of HClO4–SiO2 (7.5 g) afforded 2 in 92% isolated yield
(Table 1, entry a). Therefore, we expected to investigate the gener-
ality of the application of HClO4–SiO2 in the transprotection of
acetonides into acetates. It could be seen from the results listed
in Table 1 that glucose derivatives 3, 5, 6, and 8 were all smoothly
and immediately transformed into corresponding acetates 4, 7,
and 9, respectively, at rt in quite good yields (Table 1, entries b–
e). Additionally, these results also demonstrated that the isopro-
pylidene acetals of primary hydroxyl groups could be selectively
transformed into the corresponding acetates in the presence of
anomeric acetonides under these one-pot conditions.
As anticipated, both isopropylidene and acyl groups in 10 were
simultaneously transformed, respectively, into acetates and acylal
AcO
AcO
O
2. Results and discussion
Ac2O (5 eq)
HClO4-SiO2
O
O
In order to transform 1,2:3,5-di-O-isopropylidene-a-D-xylofura-
nose (1) straightforwardly into 3,5-di-O-acetyl-1,2-O-isopropyli-
O
O
O
CH2Cl2, rt,
1.5 h, 92%
O
O
2
1
* Corresponding author. Tel.: +86 10 68918511; fax: +86 10 68912917.
E-mail address: qpwu@bit.edu.cn (Q.-P. Wu).
Scheme 1. Selective transprotection of terminal acetonides into diacetates.
0008-6215/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2009.08.035

H.-X. Liu et al. / Carbohydrate Research 344 (2009) 2342–2348
2343
Table 1
Direct transprotection of terminal acetonides into diacetates in the presence of HClO4–SiO2
Entry
Substrate
Producta
Time (h)
1.5
Yieldb (%)
O
AcO
AcO
O
O
a
9225
O
O
O
O
O
1
2
O
AcO
O
RO
AcO
RO
O
O
O
O
O
O
b
c
d
e
3R
H
4R
Ac
Ac
Bz
Ts
7
7
8
6
8625,43
8825,43
9025
5R
6R
8R
Ac
Bz
Ts
4R
7R
9R
9025
OAc
O
AcO
OAc
f
O
8
8341
O
OAc
10
OBz
11
OAc OBz
O
AcO
O
OAc
O
g
4 (reflux)
81
OBz OAc
OBz
O
13
12
AcO
OTBDPS
O
OTBDPS
OAc
O
h
2
78
14
15
O
AcO
AcO
O
O
O
O
O
8925
O
O
i
8
OH
OAc
17
16
O
AcO
AcO
O
O
O
j
0.5
8242
O
O
S
S
19
18
Characterized by 1H NMR, 13C NMR, and ESIMS: Calcd for.
Isolated yields.
a
b
groups to give 11 in 83% yield (Table 1, entry f).41 Surprisingly,
transprotection of the two terminal isopropylidene acetals of
Treatment of compound 2 with Ac2O under the same conditions
described as above afforded compound 20, in which the anomeric
acetonide was partially cleaved to generate a 2-acetoxyisopropyl
group (Table 2, entry a). This isopropylidene chain-opened structure
is similar to those that result from catalysis by Bi(OTf)3ꢀxH2O.25 Fol-
lowing these one-pot conditions, all similar transprotections shown
in Table 2 were performed smoothly as more candidates were em-
ployed as starting materials. It is noteworthy that hydroxyl group
could not interrupt this type of transprotection, and these were acet-
ylated simultaneously (Table 2, entries b and e). We also first ob-
served that the primary tert-butyldimethylsilyl (TBDMS) ether
group in 36 was selectively transprotected to the corresponding ace-
tate along with the transprotection of the anomeric isopropylidene
group to give 37 (Table 2, entry k). As to anomeric acetonide groups
in a pyranose, a similar selective transformation was also observed
D
-
mannitol derivative 12 failed at rt, and the tetra-acetyl product
13 was obtained under reflux in CH2Cl2 (Table 1, entry g). More-
over, it was also observed that the tert-butyldiphenylsilyl
(TBDPS)-protecting group remained intact as the isopropylidene
group was selectively transformed (Table 1, entry h). Furthermore,
the formation of both products 17 and 19 provided further illustra-
tions of the selectivity and efficiency of this one-pot transprotec-
tion procedure: (1) A terminal hydroxyl acetonide was selectively
replaced by acetates in the presence of secondary hydroxyl isopro-
pylidene acetal, and (2) the anomeric hydroxy function was con-
comitantly acetylated (Table 1, entry i).
In addition, we have also tested the application of this one-pot
methodology to transprotection of anomeric acetonides (Scheme 2).

2344
H.-X. Liu et al. / Carbohydrate Research 344 (2009) 2342–2348
as
mixture 39 in quite good yield (Table 2, entry l). The anomeric aceto-
nide group in 6-O-acetyl-1,2:3,4-di-O-isopropylidene- -galacto-
pyranose (40), however, was selectively transprotected to give a
pure isomer 41 without an isopropylidene group at the 2-position
(Table 2, entry m), which might arise from the participation of the
6-acetyloxy group.
L-arabinopyranose derivative 38 was converted into an anomeric
AcO
AcO
AcO
AcO
Ac2O (5 eq)
HClO4-SiO2
OAc
O
O
a-D
O
CH2Cl2, rt,
1 h, 86%
OAc
O
O
2
20
Scheme 2. Transprotection of anomeric acetonides of furanoses into corresponding
acetylated 2-O-(20-acetoxyisopropyl)-b-
D-furanosides.
The assignment of the isopropylidene acetal chain-opened
structures listed in Table 2 are supported by 1H NMR, 13C NMR,
Table 2
Transprotection of anomeric acetonides of furanoses and pyranoses into corresponding 2-O-(2-acetoxyisopropyl)-1-O-acetyl-b-D-furanosides and 2-O-(2-acetoxyisopropyl)-1-O-
acetyl-b-D-pyranosides with HClO4–SiO2
Entry
a
Substrate
Producta
Time (h)
Yieldb (%)
AcO
AcO
AcO
AcO
OAc
O
O
1
8625
O
OAc
O
O
2
20
OAc
O
O
HO
O
AcO
b
1
87
OAc
O
O
O
21
22
TsO
AcO
TsO
AcO
OAc
O
O
c
1
84
O
O
OAc
OAc
O
24
23
BzO
RO
BzO
RO
OAc
O
O
O
O
d
e
f
25R
27R
29R
Bz
H
p-Ts
26R
28R
30R
Bz
Ac
p-Ts
1
4
1
9025
90
8525
BnO
BnO
BnO
BnO
AcO
O
O
g
1.5
8925
O
OAc
O
O
32
31
AcO
OAc
AcO
AcO
RO
AcO
RO
O
O
O
OAc
O
O
h
i
j
7R
4R
9R
Bz
Ac
p-Ts
33R
34R
35R
Bz
Ac
p-Ts
2
1.5
2
8925
8725
8325

H.-X. Liu et al. / Carbohydrate Research 344 (2009) 2342–2348
2345
Table 2 (continued)
Entry
Substrate
Producta
Time (h)
Yieldb (%)
AcO
OAc
TBDMSO
O
O
TBDMSO
OAc
k
0.5
84
TBDMSO
O
O
O
36
37
O
O
O
O
O
O
OAc
OAc
l
7.5
82
O
O
O
38
40
39
OAc
O
O
O
OAc
O
O
m
8
88
O
O
O
OAcOAc
41
a
Characterized by 1H NMR, 13C NMR, and ESIMS: Calcd for.
Isolated yields.
b
and ESIMS: Calcd for data, which also provide evidence that all
these products are pure anomeric furanosides rather than a mix-
ture. As to compound 20, the molecular structure was further con-
firmed to be a b anomer by a NOESY spectrum. In the 1H–1H
dimension of the NMR spectrum of compound 20, two cross-peaks
are observed between the resonance signals of the anomeric pro-
ton (at d 6.16) and H-3, 4 (at d 5.33), and the methyl protons in
the isopropylidene group (at d 1.45), respectively. Furthermore, it
is also observed that the methyl protons of the isopropylidene
group (at d 1.45) interact with H-3, 4 (at d 5.33) and not with H-
5 (at d 4.09–4.36). We believe that these NOESY spectroscopic data
provide strong evidence for the b-anomeric configurational
assignments.
In conclusion, we have developed a useful procedure for the
direct transprotection of terminal hydroxy acetonides into their cor-
responding acetates in an efficient process and under mild condi-
tions with HClO4–SiO2 as catalyst. This procedure also provides
excellent selectivity in transprotection of primary hydroxy aceto-
nides into acetates in the presence of anomeric acetonides of fura-
noses. Anomeric acetonides of furanoses are stereoselectively
transformed into the corresponding acetyl 2-O-(20-acetoxyisopro-
a LCMS2010 spectrometer equipped with a standard electro-
spray-ionization (ESI) interface.
3.2. Preparation of HClO4–SiO2
HClO4 (1.8 g) was added to a stirred suspension of SiO2 (23.7 g,
300–400 mesh) in EtOH (70 mL) and stirred for 10 min. The mix-
ture was concentrated under reduced pressure to give a free-flow-
ing powder (HClO4, 0.5 mmol/g) for application.
3.3. Typical synthetic procedure
HClO4–SiO2 (0.5 mmol/g, 70 mg) was added to a stirred solution
of substrate (1.0 mmol) and Ac2O (0.45 mL, 5.0 mmol) in CH2Cl2
(5 mL) at rt or in CH2Cl2 (5 mL) heated under reflux. After complete
conversion and filtration to remove catalyst, a satd aq solution of
NaHCO3 (10 mL) was added and separated. The aqueous solution
was extracted with CH2Cl2 (2 ꢁ 10 mL). The organic layer was com-
bined, washed with brine (10 mL), dried (MgSO4), and concen-
trated under reduced pressure. The crude product was purified
through short column chromatography on silica gel, which was
eluted with EtOAc–petroleum ether (bp 60–90 °C) to give the prod-
ucts that are described in the following.
pyl)-b-D-furanosides. In view of economy and environmental con-
cerns, this one-pot mild procedure might be remarkably valuable
in synthetic chemistry. The application of this methodology to the
synthesis of nucleosides and their transformations is underway in
our laboratory, and the results will be reported in due course.
3.3.1. 3,5-Di-O-acetyl-1,2-O-isopropylidene-a-D-xylofuranose
(2)
Oil; 1H NMR (400 MHz, CDCl3): dH 1.32 (s, 3H), 1.53 (s, 3H), 2.09
(s, 3H), 2.10 (s, 3H), 4.19 (dd, J 7.2 Hz and 11.6 Hz, 1H), 4.29 (m,
1H), 4.50 (m, 2H), 5.25 (d, J 3.1 Hz, 1H), 5.94 (d, J 3.7 Hz, 1H); 13C
NMR (CDCl3): dC 20.9, 21.0, 26.4, 26.9, 61.6, 76.3, 77.3, 83.6,
105.1, 112.5, 169.8, 170.8; ESIMS: Calcd for C12H18O7, m/z
274.11; found, 297.2 (M+Na)+.
3. Experimental
3.1. General
CH2Cl2 was dried over P2O5 and distilled. Ac2O was distilled be-
fore use. All reactions were monitored by thin-layer chromatogra-
phy (TLC) on silica gel F254 plates. 1H NMR and 13C NMR spectra
were recorded on a Varian Mercury 400 spectrometer or a Bruker
AV300 spectrometer in CDCl3 or DMSO-d6 and using TMS as the
internal standard. Exact mass measurements were performed on
3.3.2. 3,5,6-Tri-O-acetyl-1,2-O-isopropylidene-a-D-
glucofuranose (4)
Colorless solid, mp 76–77 °C (lit43 mp 78 °C); 1H NMR
(400 MHz, CDCl3): dH 1.32 (s, 3H), 1.53 (s, 3H), 2.02 (s, 3H), 2.06

2346
H.-X. Liu et al. / Carbohydrate Research 344 (2009) 2342–2348
(s, 6H), 4.13 (dd, J 5.6 Hz and 12.3 Hz, 1H), 4.42 (dd, J 3.0 Hz and
9.4 Hz, 1H), 4.49 (d, J 3.6 Hz, 1H), 4.57 (dd, J 2.4 and 12.3 Hz, 1H),
5.22 (m, 1H), 5.35 (d, J 2.8 Hz, 1H), 5.93 (d, J 4.0 Hz 1H); 13C NMR
(CDCl3): dC 20.9, 21.0, 26.4, 27.0, 63.6, 67.7, 74.9, 77.0, 83.4,
105.4, 112.7, 169.8, 169.9, 170.8; ESIMS: Calcd for C15H22O9, m/z
346.13; found, m/z 369.1 (M+Na)+.
3.3.9. 2-(R)-[10(R), 20-Di-O-acetylethyl]-[1,3]oxathiolan-5-one
(19)
Colorless solid, mp 75–77 °C; 1H NMR (DMSO-d6): dH 2.00 (s,
3H), 2.09 (s, 3H), 3.78 (d, J 16.8 Hz, 1H), 3.85 (d, J 16.8 Hz, 1H),
4.16 (dd, J 6.8 Hz and 12.0 Hz, 1H), 4.26 (dd, J 4.4 Hz and 12.0 Hz,
1H), 5.21 (m, 1H), 5.84 (d, J 4.0 Hz, 1H); 13C NMR (DMSO-d6): dC
20.6, 20.7, 30.0, 61.9, 72.5, 78.8, 169.6, 170.2, 173.2; HRESIMS:
Calcd for C9H12O6S m/z 248.0355; found, m/z 248.0357 (M+Na)+.
3.3.3. 5,6-Di-O-acetyl-3-O-benzoyl-1,2-O-isopropylidene-a-D-
glucofuranose (7)
Oil; 1H NMR (CDCl3): dH 1.34 (s, 3H), 1.57 (s, 3H), 1.94 (s, 3H),
2.06 (s, 3H), 4.19 (dd, J 5.2 Hz and 12.4 Hz, 1H), 4.59 (m, 3H),
5.32 (m, 1H), 5.54 (d, J 2.4 Hz, 1H), 5.99 (d, J 3.2 Hz, 1H), 7.45 (m,
2H), 7.58 (m, 1H), 7.99 (d, J 8.0 Hz, 2H); 13C NMR (CDCl3): dC
20.9, 21.0, 26.5, 27.0, 63.4, 68.1, 75.9, 77.3, 83.5, 105.4, 112.8,
128.8, 129.2, 130.0, 133.9, 165.5, 169.6, 170.8; ESIMS: Calcd for
C20H24O9, m/z 408.14; found, m/z 431.1 (M+Na)+.
3.3.10. 1,3,5-Tri-O-acetyl-2-O-(2-acetoxyisopropyl)-b-D-
xylofuranoside (20)
Oil; 1H NMR (CDCl3): dH 1.45 (s, 3H), 1.46 (s, 3H), 2.05 (s, 3H),
2.06 (s, 3H), 2.07 (s, 3H), 2.10 (s, 3H), 4.10 (dd, J 3.6 Hz and
8.0 Hz, 1H), 4.35 (m, 2H), 5.33 (m, 2H), 6.16 (d, J 1.6 Hz, 1H); 13C
NMR (CDCl3): dC 13.6, 13.7, 13.8, 14.1, 19.6, 20.0, 54.9, 62.4, 62.5,
73.3, 89.4, 106.8, 162.8, 162.9, 163.0, 163.5; ESIMS: Calcd for
C16H24O10, m/z 376.14; found, m/z 399.1 (M+Na)+.
3.3.4. 5,6-Di-O-acetyl-1,2-O-isopropylidene-3-O-p-
toluenesulfonyl-a-D-glucofuranose (9)
3.3.11. 1,3-Di-O-acetyl-2-O-(2-acetoxyisopropyl)-5-deoxy-b-D-
xylofuranoside (22)
Oil; 1H NMR (CDCl3): dH 1.28 (s, 3H), 1.48 (s, 3H), 1.95 (s, 3H),
2.03 (s, 3H), 2.44 (s, 3H), 4.06 (dd, J 4.0 Hz and 12.4 Hz, 1H), 4.45
(t, J 6.8 Hz, 1H), 4.57 (d, J 12.4 Hz, 1H), 4.69 (d, J 3.2 Hz, 1H), 5.03
(m, 2H), 5.89 (d, J 3.2 Hz, 1H), 7.34 (d, J 8.0 Hz, 2H), 7.77 (d, J
8.0 Hz, 2H); 13C NMR (CDCl3): dC 21.0, 21.9, 26.5, 26.9, 29.9, 62.8,
67.8, 76.4, 80.2, 83.0, 105.1, 113.0, 128.3, 130.2, 132.8, 145.8,
169.8, 170.7; ESIMS: Calcd for C20H26O10S, m/z 458.12; found, m/z
481.2 (M+Na)+.
Oil; 1H NMR (DMSO-d6): dH 1.14 (d, J 6.4 Hz, 3H), 1.39 (s,
3H),1.41 (s, 3H), 1.99 (s, 3H), 2.03 (s, 3H), 2.08 (s, 3H), 4.35 (dd, J
2.4 Hz and 6.4 Hz, 1H), 5.05 (m, 1H), 5.12 (t, J 4.2 Hz, 1H), 6.13
(d, J 2.3 Hz, 1H); 13C NMR (DMSO-d6): dC 16.2, 20.6, 20.8, 21.0,
26.7, 26.9, 68.2, 72.6, 80.2, 95.6, 112.7, 169.7, 170.0; ESIMS: Calcd
for C14H22O8, m/z 318.13; found, m/z 341.1 (M+Na)+.
3.3.12. 2-O-(2-Acetoxyisopropyl)-1,3-di-O-acetyl-5-O-p-
toluenesulfonyl-b-D-xylofuranoside (24)
Oil; 1H NMR(CDCl3): dH 1.44 (s, 6H), 2.00 (s, 3H), 2.07 (s, 3H),
2.09 (s, 3H), 2.45 (s, 3H), 4.23 (dd, J 2.0 Hz and 4.0 Hz, 2H), 4.38
(dd, J 2.4 Hz and 4.0 Hz, 1H), 5.23 (d, J 5.2 Hz, 1H), 5.3 (dd, J
4.0 Hz and 5.6 Hz, 1H), 6.13 (d, J 1.0 Hz, 1H), 7.36 (d, J 4.0 Hz,
2H), 7.78 (d, J 4.0 Hz, 2H); 13C NMR(CDCl3): dC 20.8, 20.9, 21.4,
21.9, 26.9, 27.2, 67.3, 69.3, 69.5, 80.3, 96.3, 114.1, 128.3, 130.2,
132.7, 145.4, 169.9, 170.2; ESIMS: Calcd for C21H28O11S, m/z
488.14; found, m/z 511.2 (M+Na)+.
3.3.5. (R)-Propane-1,1,2,3-tetraol tetraacetate (1,1,2,3-tetra-O-
acetyl-D-glyceraldehyde hydrate) (11)
Oil; 1H NMR (DMSO-d6): dH 2.01 (s, 3H), 2.04 (m, 6H), 2.09 (m,
3H), 4.16 (dd, J 7.2 Hz and 12.4 Hz, 1H), 4.29 (dd, J 3.2 Hz and
12 Hz, 1H), 5.20 (m, 1H), 6.84 (dd, J 1.6 Hz and 4.4 Hz, 1H); 13C
NMR (DMSO-d6): dC 20.9, 21.0, 21.1, 61.4, 69.9, 86.5, 169.0, 170.2,
170.7. The NMR spectra matched that reported41 in the literature,
allowing for the fact that the latter spectra were measured in CDCl3
rather than in DMSO-d6 solution.
3.3.13. 2-O-(2-Acetoxyisopropyl)-1-O-acetyl-3,5-di-O-benzoyl-
b-
D
-xylofuranoside (26)
3.3.6. 1,2,5,6-Tetra-O-acetyl-3,4-di-O-benzoyl-D-mannitol (13)
Oil; 1H NMR (CDCl3): dH 1.50 (s, 3H), 1.54 (s, 3H), 2.02 (s, 6H),
Oil; 1H NMR (DMSO-d6): dH 1.93 (s, 12H), 4.14 (dd, J 5.2 Hz and
12.0 Hz, 2H), 4.28 (dd, J 3.2 Hz and 12.4 Hz, 2H); 5.24 (m, 2H), 5.72
(d, J 7.2 Hz, 2H), 7.56 (m, 4H), 7.70 (m, 2H), 8.01 (m, 4H); 13C NMR
(DMSO-d6): dC 20.5, 20.6, 61.6, 68.4, 68.5, 128.8, 129.1, 129.7,
4.52 (m, 1H), 4.62 (m, 2H), 5.74 (m, 2H), 6.33 (d, J 2.4 Hz, 1H),
7.44 (m, 4H), 7.57 (m, 2H), 8.03 (m, 4H); 13C NMR (CDCl3): dC
20.8, 21.1, 26.7, 26.8, 62.9, 69.6, 70.1, 80.5, 96.5, 113.8, 128.4,
128.6, 128.9, 129.4, 129.7, 129.9, 133.3, 133.6, 165.5, 166.1,
170.0, 171.0; ESIMS: Calcd for C26H28O10, m/z 500.49; found, m/z
523.1 (M+Na)+.
134.1, 164.8, 169.4, 170.0; ESIMS: Calcd for C28H30O12, m/z
558.17; found, m/z 581.3 (M+Na)+.
3.3.7. 1,2-Di-O-acetyl-3-O-tert-butyldiphenylsilyl-D-glycerol
(15)
3.3.14. 2-O-(2-Acetoxyisopropyl)-1,3-di-O-acetyl-5-O-benzoyl-
b-D
-xylofuranoside (28)
Oil; 1H NMR (CDCl3): dH 1.06 (s, 9H), 2.04 (s, 6H), 3.78 (m, 2H),
4.23 (dd, J 6.0 Hz and 12.0 Hz, 1H), 4.41 (m, 1H), 5.17 (m, 1H), 7.42
(m, 6H), 7.66 (m, 4H); 13C NMR (CDCl3): dC 19.5, 21.0, 21.2, 26.9,
62.4, 62.9, 71.9, 128.0, 130.1, 133.2, 133.3, 135.8, 170.5, 170.9;
ESIMS: Calcd for C23H30O5Si, m/z 414.19; found, m/z 437.2 (M+Na)+.
Oil; 1H NMR (DMSO-d6): dH 1.42 (s, 3H), 1.43 (s, 3H), 2.05 (s,
3H), 2.07 (s, 3H), 2.09 (s, 3H), 4.34 (dd, J 6.8 Hz and 12.0 Hz, 1H),
4.48 (m, 2H), 5.42 (m, 2H), 6.18 (d, J 2.0 Hz, 1H), 7.54 (m, 2H),
7.67 (m, 1H), 7.92 (m, 2H); 13C NMR (DMSO-d6): dC 20.6, 20.7,
21.0, 26.72, 27.0, 62.8, 69.1, 69.7, 80.2, 95.7, 113.0, 129.0, 129.4,
133.7, 165.4, 169.8, 169.9; ESIMS: Calcd for C21H26O10, m/z
438.15; found, m/z 461.2 (M+Na)+.
3.3.8. 1,5,6-Tri-O-acetyl-2,3-O-isopropylidene-a,b-D-
mannofuranoside (17)
Oil; 1H NMR (CDCl3): dH 1.30 (s, 3H), 1.46 (s, 3H), 2.08 (s, 9H),
4.16 (dd, J 5.6 Hz and 12.4 Hz, 1H), 4.23 (dd, J 3.6 Hz and 7.6 Hz,
1H), 4.60 (dd, J 2.4 Hz and 12.4 Hz, 1H), 4.67 (d, J 6.0 Hz, 1H),
4.80 (dd, J 4.0 Hz and 6.0 Hz, 1H), 5.29 (m, 1H), 6.16 (s, 1H); 13C
NMR (CDCl3): dC 21.0, 21.1, 21.2, 25.1, 26.2, 63.2, 69.2, 79.4, 80.2,
84.9, 100.8, 113.7, 169.4, 169.8 and 170.8; ESIMS: Calcd for
C15H22O9, m/z 346.33; found, 369.3 (M+Na)+.
3.3.15. 2-O-(2-Acetoxyisopropyl)-1-O-acetyl-5-O-benzoyl-3-O-
p-toluenesulfonyl-b-D-xylofuranoside (30)
Oil; 1H NMR (CDCl3): dH 1.36 (s, 3H), 1.45 (s, 3H), 2.06 (s, 3H),
2.08 (s, 3H), 2.39 (s, 3H), 4.39 (m, 2H), 4.53 (m, 1H), 5.14 (dd, J
3.6 Hz and 5.2 Hz, 1H), 5.52 (dd, J 5.2 Hz and 10.4 Hz, 1H), 6.33
(d, J 2.2 Hz, 1H), 7.28 (t, J 8.0 Hz, 2H), 7.46 (m, 2H), 7.59 (m, 1H),
7.81 (d, J 8.3 Hz, 2H), 8.01 (d, J 0.7 Hz, 2H); 13C NMR (CDCl3): dC

H.-X. Liu et al. / Carbohydrate Research 344 (2009) 2342–2348
2347
20.8, 21.1, 26.4, 26.8, 29.7, 62.2, 68.9, 77.0, 80.4, 96.5, 114.2, 127.8,
128.5, 129.3, 129.7, 129.9, 133.3, 145.4, 165.7, 169.9, 170.0; ESIMS:
Calcd for C26H30O11S, m/z 550; found, m/z 550 (M+).
108.6, 111.3, 112.5, 169.9, 170.0, 170.1, 170.3; ESIMS: Calcd for
15H24O8, m/z 332.15; found, 355.2 (M+Na)+.
C
3.3.22. 1,2,6-Tri-O-acetyl-3,4-O-isopropylidene-a-D-
galactopyranoside (41)
3.3.16. 2-O-(2-Acetoxyisopropyl)-1-O-acetyl-3,5-di-O-benzyl-b-
Oil; 1H NMR (DMSO-d6): dH 1.29 (s, 3H), 1.42 (s, 3H), 2.03 (s,
3H), 2.05 (s, 3H), 2.10 (s, 3H), 4.18 (m, 2H), 4.32 (m, 1H), 4.38
(m, 2H), 4.88 (dd, J 3.6 Hz and 7.2 Hz, 1H), 6.04 (d, J 3.6 Hz, 1H);
13C NMR (DMSO-d6): dC 20.5, 20.6, 25.9, 27.4, 62.8, 67.7, 69.2,
71.8, 72.3, 88.4, 109.3, 169.0, 169.8, 170.2; ESIMS: Calcd for
C15H22O9, m/z 346.13; found, 369.2 (M+Na)+.
D
-xylofuranoside (32)
Oil; 1H NMR (CDCl3): dH 1.45 (s, 3H), 1.48 (s, 3H), 2.07 (s, 3H),
2.08 (s, 3H), 3.68 (m, 2H), 3.94 (t, J 4.8 Hz, 1H), 4.34 (dd, J 2.4 Hz
and 3.6 Hz, 1H), 4.51 (dd, J 12.0 Hz and 22.4 Hz, 2H), 4.72 (s, 2H),
5.30 (m, 1H), 6.26 (d, J 2.8 Hz, 1H), 7.32 (m, 10H); 13C NMR (CDCl3):
dC 21.3, 21.4, 26.7, 27.0, 68.1, 72.0, 73.4, 74.6, 76.2, 81.6, 96.8,
113.2, 128.0, 128.1, 128.6, 138.0, 138.1, 170.4, 170.5; ESIMS: Calcd
for C26H32O8, m/z 472.53; found, m/z 495.3 (M+Na)+.
Acknowledgments
Financial supports of this work by the NNSFC and the Ministry of
Science and Technology of China (2006AA100216) are appreciated.
3.3.17. 2-O-(2-Acetoxyisopropyl)-1,5,6-tri-O-acetyl-3-O-
benzoyl-b-D-glucofuranoside (33)
Oil; 1H NMR (DMSO-d6): dH 1.39 (s, 6H), 1.92 (s, 3H), 1.99 (s,
3H), 2.02 (s, 3H), 2.05 (s, 3H), 4.12 (m 1H), 4.28 (dd, J 2.8 Hz and
12.3 Hz, 1H), 4.51 (dd, J 2.0 Hz and 4.6 Hz, 1H), 5.15 (m, 1H), 5.47
(dd, J 3.7 Hz and 6.8 Hz, 1H), 5.8 (t, J 4.2 Hz, 1H), 6.22 (d, J 2.0 Hz,
1H), 7.57 (m, 2H), 7.70 (m,1H), 7.96 (m, 2H); 13C NMR (DMSO-
d6): dC 20.4, 20.5, 20.8, 26.6, 26.9, 61.4, 68.3, 68.8, 69.2, 80.7,
95.5, 112.9, 128.8, 128.9, 129.3, 133.9, 164.9, 169.2, 169.5, 169.6,
170.0; ESIMS: Calcd for C24H30O12, m/z 510.17; found, m/z 533.2
(M+Na)+.
Supplementary data
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.carres.2009.08.035.
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Oil; 1H NMR (CDCl3): dH 1.32 (s, 3H), 1.42 (s, 3H), 2.06 (s, 3H),
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6.8 Hz, 1H), 6.30 (s, 1H), 7.35 (d, J 8.4 Hz, 2H), 7.81 (d, J 8.0 Hz,
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61.3, 68.7, 69.4, 76.0, 81.0, 96.5, 114.2, 128.2, 130.0, 133.5, 145.5,
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2.05 (s, 3H), 2.07 (s, 3H), 2.10 (s, 3H), 4.05 (t, J 4.0 Hz, 1H), 4.22
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6H), 3.95–4.44 (m, 5H), 6.06–6.27 (m, 1H); 13C NMR (DMSO-d6):
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73.8, 74.4, 74.7, 75.6, 77.0, 77.3, 80.1, 83.9, 93.2, 96.7, 108.4,

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