Cleavage of the C-C linkage between the sugar and the aglycon in C-glycosylphloroacetophenone, and the NMR spectral characteristics of the resulting di-C-glycosyl compound

Article abstract of DOI:10.1016/S0008-6215(01)00183-5

The treatment of unprotected mono-C-β-D-glucopyranosylphloroacetophenone with a cation-exchange resin in anhydrous acetonitrile afforded both a phloroacetophenone and a di-C-β-D-glucopyranosylphloroacetophenone. Treatment of an unprotected mono-C-(2-deoxy-β-D-arabino-hexopyranosyl)phloroacetophenone (mono-C-2-deoxy-β-D-glucopyranosylphloroacetophenone) also afforded both the aglycon and di-C-(2-deoxy-β-D-arabino-hexopyranosyl)phloroacetophenone. The reaction mixtures were acetylated, and the structures of the isolated products were determined by NMR spectroscopy. This is the first demonstration of the formation of a di-C-glycosyl compound during the chemical cleavage of the C-C linkage between the sugar and the aglycon in an aryl C-glycosyl derivative.

Full text of DOI:10.1016/S0008-6215(01)00183-5

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Carbohydrate Research 334 (2001) 207–213
Cleavage of the C–C linkage between the sugar and the
aglycon in C-glycosylphloroacetophenone, and the NMR
spectral characteristics of the resulting di-C-glycosyl
compound
Toshihiro Kumazawa,* Takayuki Kimura, Shigeru Matsuba, Shingo Sato,
Jun-ichi Onodera
Department of Chemistry and Chemical Engineering, Faculty of Engineering, Yamagata Uni6ersity, 4-3-16 Jonan,
Yonezawa, Yamagata 992-8510, Japan
Received 15 May 2001; accepted 27 June 2001
Abstract
The treatment of unprotected mono-C-b-
anhydrous acetonitrile afforded both a phloroacetophenone and a di-C-b-
Treatment of an unprotected mono-C-(2-deoxy-b- -arabino-hexopyranosyl)phloroacetophenone (mono-C-2-deoxy-
b- -glucopyranosylphloroacetophenone) also afforded both the aglycon and di-C-(2-deoxy-b- -arabino-hexopyran-
D
-glucopyranosylphloroacetophenone with a cation-exchange resin in
D
-glucopyranosylphloroacetophenone.
D
D
D
osyl)phloroacetophenone. The reaction mixtures were acetylated, and the structures of the isolated products were
determined by NMR spectroscopy. This is the first demonstration of the formation of a di-C-glycosyl compound
during the chemical cleavage of the C–C linkage between the sugar and the aglycon in an aryl C-glycosyl derivative.
© 2001 Elsevier Science Ltd. All rights reserved.
Keywords: C-Glycosylflavonoid; C-Glycosyl compound; Di-C-Glycosyl compound; C–C linkage; Cation exchange resin
1. Introduction
use as therapeutic agents for clinical use. C-
glycosylflavonoids are plant constituents,
some of which are biologically active.2 Re-
cently, we reported on the synthesis of C-gly-
cosylphloroacetophenone derivatives,3 which
represent synthetic intermediates in the prepa-
ration of C-glycosylflavonoids, and for the
regio- and stereoselective synthesis of isoori-
entin, 6-C-glucosylflavone.4 In the field of C-
glycosylflavonoid chemistry, three types of
reactions are possible under hydrolytic condi-
tions:5 (1) the Wessely–Moser rearrangement
of the aglycon moiety, but not the sugar; (2)
the expected pyranose–furanose interconver-
sion; and (3) the acid-catalyzed degradation of
the C-glycosyl compound. In order to avoid
Because of their biological activity, an effi-
cient synthesis of aryl C-glycosylic compounds
(aryl ‘C-glycosides’) has been a subject of
considerable interest, and several effective
methods in this area have been reported to
date.1 The characteristic properties of aryl C-
glycosyl compounds include resistance to acid
hydrolysis, in contrast to O-glycosides. There-
fore, these compounds have the potential for
* Corresponding author. Tel.: +81-238-263122; fax: +81-
238-263413.
E-mail address: tk111@dip.yz.yamagata-u.ac.jp (T. Ku-
mazawa).
0008-6215/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0008-6215(01)00183-5

208
T. Kumazawa et al. / Carbohydrate Research 334 (2001) 207–213
the Wessely–Moser rearrangement of the
aglycon moiety in the flavone during acid
nolic substituents (red–brown with 5% ferric
chloride spray), in addition to mono-C-gluco-
syl compound 1a and a number of noncolored
byproducts. Because of difficulties in the
purification of these compounds, the reaction
mixture was acetylated. After silica-gel
column chromatography, acetylphloroace-
tophenone 2 was obtained in 31% yield, along
hydrolysis,
C-glycosylphloroacetophenones
were used, and it was shown that they could
be converted into spiroketal compounds on
treatment with a catalytic amount of p-tolue-
nesulfonic acid in hot water.6 However, Mi-
namikawa and co-workers reported that
bergenin, a C-glucoside derivative of 4-O-
methylgallic acid, was transformed into a 4-O-
methylgallic acid by a strain of soil bacteria.7
Hattori and co-workers have showed that sev-
eral C-glycosyl compounds, including C-gly-
cosylflavonoids, were transformed into their
corresponding aglycons by human intestinal
bacteria on the course of a study of the
metabolites of C-glycosyl compounds.8 These
results provide a clear demonstration of the
enzymic hydrolysis of C-glycosyl compounds.
On the other hand, treatment with a hy-
droiodic acid–phenol mixture readily yielded
the corresponding isoflavones from C-glyco-
sylisoflavones.9 Ferric chloride oxidation also
has been used to identify the C-glycosyl
residue in C-glycosylisoflavones.9,10 These
chemical methods involve the cleavage of the
C–C linkage in the aryl C-glycosyl compound
and show that it is possible, using enzymic or
chemical methods, to convert them to the
corresponding aglycon and sugar. The present
report shows that the C–C bond linkage be-
tween the sugar and the carbon atom of an
aglycon in the C-glycosylphloroacetophenone
can be cleaved using a strongly acidic cation-
exchange resin in anhydrous acetonitrile, re-
sulting in the production of the aglycon and
di-C-glycosylphloroacetophenone. The forma-
tion of such a di-C-glycosyl compound under
conditions of acidic hydrolysis has not previ-
ously been reported.
with
mono-C-b- -glucosylphloroacetophe-
D
none acetate 3a in 22% yield, and di-C-b- -
D
glucosylphloroacetophenone acetate 4a in 9%
yield (Entry 2). The structure of the aglycon
acetate 2 was confirmed by a comparison of
1
its H NMR spectrum with an authentic sam-
1
ple. A H NMR spectrum of the mono-C-glu-
cosyl derivative 3a was obtained at 50 °C in
CDCl3 because a structural assignment by
NMR spectroscopy at ambient temperature
was hampered by the slow rotation around
the C-1ꢀaglycon bond. The 13C NMR spec-
trum of compound 3a in CDCl3 at ambient
temperature showed that some of the peaks
were broad and that the peaks that corre-
spond to the aglycon represented the pairing
1
of major and minor peaks. H NMR spectra
of the di-C-glucosyl derivative 4a showed that
the methine and methylene signals of each
glucose moiety could be identified indepen-
dently at ambient temperature in CDCl3. The
reason for this is mentioned above. To elimi-
nate the rotational hindrance in compound 4a,
1
the H NMR spectrum was obtained at an
elevated temperature of 140 °C in Me2SO-d6.
Although a slow decomposition of compound
1
4a was observed during this H NMR experi-
1
ment at this temperature, the H NMR spec-
tra showed that the signals were sharpened,
and that the chemical shift values for both the
methine and methylene protons of the glucose
moieties were clear and equivalent. Judging
from J1%,2%=J1%%,2%%=9.5 Hz, the anomeric
configuration of both of the glucose moieties
of compound 4a is b. We previously described
the b stereoselective synthesis of mono-C-
glucopyranosylphloroacetophenone using 2,4-
dibenzyl-protected phloroacetophenone as a
glycosyl acceptor, benzyl-protected glucosyl
fluoride as a glycosyl donor, and boron tri-
fluoride diethyl etherate as an activator, in
CH2Cl2.3a In this study, the formation of the
di-C-glucosyl compound 4a, having a b
2. Results and discussion
Treatment of a solution of C-b- -gluco-
D
pyranosylphloroacetophenone (1a)3a with
Dowex® 50W (H+ form) at ambient tempera-
ture in anhydrous acetonitrile showed, by
thin-layer chromatography (TLC), the pres-
ence of two new zones at the top and near the
bottom of the plate that corresponded to phe-

T. Kumazawa et al. / Carbohydrate Research 334 (2001) 207–213
209
configuration for both of the glucose moieties,
was verified when unprotected starting mate-
rial 1a was used. In relation to this fact, the
glucose moieties in all natural di-C-gluco-
sylflavonoids isolated thus far are of the b
configuration. The 13C NMR spectrum of
compound 4a at ambient temperature in
CDCl3 showed that the chemical shift values
for C-3 and C-5 of the aromatic ring were not
equivalent, and that the chemical shift values
for the C-2 and C-6 were also not equivalent.
We previously reported on the synthesis of
sugar oxonium ion by treatment with acid.
The oxonium ion attacked the mono-C-gluco-
syl compound 1a to give the unprotected di-
C-glucosyl compound. The mechanism of the
formation of the unprotected di-C-glucosyl
compound is not clear. It is possible that the
second C-glucosylation of the mono-C-gluco-
syl compound involved a Friedel–Crafts type
reaction or underwent an O“C glycosylic
rearrangement. To the contrary, it is also pos-
sible that the unprotected di-C-glucosyl com-
pound was converted to the unprotected
mono-C-glucosyl compound 1a by acid, and
was then converted to the aglycon. In addi-
tion, the decomposition of the oxonium ion is
also possible during the reaction. Therefore,
the yield of the di-C-glucosyl compound 4a
would not be expected to be over 10%. The
possibility that a hydroxy group, positioned at
C-2 of the glucose moiety of the mono-C-glu-
cosyl compound 1a, influences the formation
of the di-C-glycosylation product also cannot
be excluded.
3,5-di-(2,3,4,6-tetra-O-acetyl-b- -glucopyran-
D
osyl)phloroacetophenone 4c.11 When the 13C
NMR spectra of the fully protected di-C-glu-
cosyl compound 4a was compared with that
of compound 4c, the data showed that the
chemical shift values for the C-3 and C-5, as
well as C-2 and C-6 of its aromatic ring, were
equivalent. These differences result from the
existence of acetyl groups on the phenolic
hydroxy groups and are the result of the slow
rotation around the C-1ꢀaglycon bonds.
HMBC spectra of the compound 4a indicated
that the H-1% signal was correlated to the C-2,
C-3, and the C-4 signals, and that the H-1%%
signal was correlated to the C-4, C-5, and the
C-6 signals. Therefore, all carbon signals in
the aromatic ring could be assigned.
The cleavage of the C–C linkage of C-glu-
cosylphloroacetophenone 1a with Dowex®
50W (H+) was examined under several con-
ditions, and the results are summarized in
Table 1. As a matter of course, when less
cation-exchange resin was used, the yields of
the aglycon acetate 2 and the di-C-glucosyl
compound 4a decreased, and when the reac-
tion was carried out at the low temperature,
their yields also decreased. Compound 1a
could be cleaved to generate an aglycon and a
We next examined the cleavage of an un-
protected C-(2-deoxy-b- -arabino-hexopyran-
D
osyl)phloroacetophenone 1b3a [C-(2-deoxy-b-
D
-glucopyranosyl)phloroacetophenone], which
does not contain a 2-OH group. The reaction
was carried out under identical conditions,
and the resulting mixture was acetylated.
Acetylphloroacetophenone 2 in 31% yield,
mono - C - (2-deoxy-b-
syl)phloroacetophenone acetate 3b in 22%
yield, and di-C-(2-deoxy-b- -arabino-hexopy-
D
-arabino-hexopyrano-
D
ranosyl)phloroacetophenone acetate 4b in 9%
yield were obtained, respectively. The yield of
compound 4b was less than 10%, by analogy
with the di-C-glucosyl compound 4a. We con-
clude from this experiment that the 2-OH
group of the glucose moiety is not a factor in
Table 1
Cleavage of the C–C linkage of mono-C-glucosyl 1a and formation of both the corresponding aglycon 2 and di-C-glucosyl 4a
Entry 1a (mg)
Dowex®-50W CH3CN (mL) Time (h)
(H+) (g)
Temperature Yield 2 (%)
(°C)
Yield 3a (%) Yield 4a (%)
1
2
3
4
5
100
100
100
100
100
0.3
1.5
0.3
1.5
7.5
10
50
50
50
100
0.5
0.5
0.5
5
rt
rt
rt
15
31
17
32
15
50
22
53
27
67
8.2
9.1
5.0
9.3
4.4
0
5
−23

210
T. Kumazawa et al. / Carbohydrate Research 334 (2001) 207–213
cleavage of the C–C linkage between the
sugar and the aglycon in the aryl C-glycosyl
compound (Scheme 1).
3. Experimental
General methods.—All nonaqueous reac-
tions were carried out under an atmosphere of
dry Ar using freshly distilled solvent, unless
otherwise noted. All reactions were monitored
by TLC, which was carried out on 0.25 mm
Silica Gel 60 F254 plates (E. Merck) using
either UV light, a 5% ethanolic solution of
ferric chloride or a 5% ethanolic solution of
phosphomolybdic acid with heat as develop-
ing agents. Fuji Silysia BW-300 was used for
silica-gel column chromatography. Optical ro-
tations were recorded using CHCl3 as the
solvent on a JASCO DIP-370 digital polar-
imeter. IR spectra were recorded on a
HORIBA FT-720 IR spectrometer as KBr
pellets. Mass spectra were recorded on a
JEOL JMS-AX-505-HA mass spectrometer
under electron ionization (EI) conditions or
under fast-atom bombardment (FAB) condi-
tions using 3-nitrobenzyl alcohol as the ma-
Scheme 1.
1
this reaction. Whereas the H NMR spectrum
of the compound 3b was clear at ambient
1
temperature, the H NMR experiment of the
di-C-2-deoxy-glucosyl compound 4b had to be
carried out at 50 °C in CDCl3 because the
structural assignment by NMR spectroscopy
at ambient temperature was hampered by the
slow rotation around the C-1ꢀaglycon bond.
Based on the fact that J1%,2%ax=J1%%,2%%ax=9.5
Hz, the anomeric configuration of both of the
2-deoxy-glucose moieties of compound 4b can
be assigned as b. The 13C NMR spectrum of
compound 4b in CDCl3 at ambient tempera-
ture showed that some of carbon peaks of the
2-deoxy-glucose moieties were broad. In par-
ticular, the carbon signals of C-1% and C-1%% of
the sugar moieties were broadened. The rea-
son for this is mentioned above. Alternatively,
the 13C NMR spectrum of compound 4b in
acetone-d6 at ambient temperature showed
that the C-1% and C-1%% signals were identified
at 72.0 and 73.1 ppm, respectively, although
these peaks may be interchanged.
1
trix. H NMR spectra were recorded on a
VARIAN INOVA 500 instrument using
Me4Si as the internal reference.
2,4,6-Tri-acetoxyacetophenone (2), 2,4,6-tri-
acetoxy-3-C-(2,3,4,6-tetra-O-acetyl-i- -glu-
D
copyranosyl)acetophenone (3a), and 2,4,6-tri-
acetoxy-3,5-bis-C-(2,3,4,6-tetra-O-acetyl-i-
D
a
-
glucopyranosyl)acetophenone (4a).—To
stirred solution of compound 1a3a (100 mg),
Dowex®-50W (H+) which had been dried at
70 °C for 3 h under vacuo, was added. After
0.5 h, MeOH was added to the reaction mix-
ture, and it was filtered to remove the resin.
The solvent was evaporated under reduced
pressure. The residual syrup was acetylated
for 12 h at 0 °C using Ac2O, pyridine, and a
catalytic amount of 4,4-dimethylaminopy-
ridine (DMAP). The reaction mixture was
poured into 0.5 M HCl in ice and extracted
with EtOAc. The organic layer was washed
with water and brine, and the solvent was
evaporated at reduced pressure. The residual
syrup was purified by column chromatogra-
phy on silica gel (1:1“1:2 hexane–EtOAc) to
In conclusion, the unprotected C-glyco-
sylphloroacetophenones gives the aglycon and
the
di-C-glycosylphloroacetophenone
on
treatment with a cation-exchange resin in an-
hydrous acetonitrile. Alternatively, they give
the spiroketal compounds on treatment with
p-toluenesulfonic acid in hot water. This is the
first demonstration of the formation of a di-
C-glycosyl compound during the chemical

T. Kumazawa et al. / Carbohydrate Research 334 (2001) 207–213
211
H-5%%), 3.92 (dd, 1 H, J5%,6%a 1.5, Jgem 13.5 Hz,
H-6%a), 3.98 (dd, 1 H, J5%%,6%%a 1.5, Jgem 13.5 Hz,
H-6%%a), 4.34 (d, 1 H, J1%,2% 10.0 Hz, H-1%), 4.40
(dd, 1 H, J5%,6%b 4.9, Jgem 13.5 Hz, H-6%b), 4.42
(dd, 1 H, J5%%,6%%b 4.9, Jgem 13.5 Hz, H-6%%b), 4.78
(d, 1 H, J1%%,2%% 10.0 Hz, H-1%%), 5.130 (dd, 1 H,
J3%,4% 9.3, J4%,5% 9.8 Hz, H-4%), 5.135 (dd, 1 H,
J3%%,4%% 9.3, J4%%,5%% 9.8 Hz, H-4%%), 5.22 (t, 1 H,
give compound 2 (28 mg, 31%) as a colorless
powder, compound 3a (41 mg, 22%) as a
colorless powder and compound 4a (26 mg,
9%) as a crude syrup. Recrystallization of
crude compound 4a from hexane–Et2O gave
an analytically pure sample.
Physicochemical data for (3a): mp 191–
193 °C; [h]2D5 −24° (c 1.0, CHCl3); Rf 0.26 (1:1
hexane–EtOAc); IR (KBr): w 3107, 3066,
2979, 2943, 2895, 1774, 1755, 1701, 1612,
1429, 1371, 1238, 1213, 1182, 1151, 1101,
J2%%,3%%=J3%%,4%% 9.3 Hz, H-3%%), 5.32 (t, 1 H, J2%,3%
=
J3%,4% 9.3 Hz, H-3%), 5.57 (dd, 1 H, J2%%,3%% 9.3,
J1%%,2%% 10.0 Hz, H-2%%), 5.71 (dd, 1 H, J2%,3% 9.3,
1
1
1055, 912, 901, 877, 839 cm−1; H NMR
J1%,2% 10.0 Hz, H-2%); H NMR (Me2SO-d6 at
(CDCl3 at 50 °C): l 1.79 (s, 3 H, ꢀOAc), 2.00
(s, 3 H, ꢀOAc), 2.03 (s, 3 H, ꢀOAc), 2.05 (s, 3
H, ꢀOAc), 2.25 (s, 3 H, ArOAc), 2.31* (s, 3 H,
ArOAc), 2.37* (s, 3 H, ArOAc), 2.41 (s, 3 H,
ArAc), 3.75 (ddd, 1 H, J5%,6%a 2.2, J5%,6%b 4.6, J4%,5%
10.1 Hz, H-5%), 3.99 (dd, 1 H, J5%,6%a 2.2, Jgem
12.6 Hz, H-6%a), 4.37 (dd, 1 H, J5%,6%b 4.6,
Jgem12.6 Hz, H-6%b), 4.73* (br. d, 1 H, J1%,2% 9.9
Hz, H-1%), 5.14 (dd, 1 H, J3%,4% 9.3, J4%,5% 10.1
Hz, H-4%), 5.25 (t, 1 H, J2%,3%=J3%,4% 9.3 Hz,
H-3%), 5.61* (dd, 1 H, J2%,3% 9.3, J1%,2% 9.9 Hz,
H-2%), 7.01* (br. s, 1 H, ArH). The (*) indi-
140 °C): l 1.73 (s, 6 H, ꢀOAc), 1.92 (s, 6 H,
ꢀOAc), 1.96 (s, 6 H, ꢀOAc), 1.98 (s, 6 H,
ꢀOAc), 2.27 (s, 6 H, ꢀOAc), 2.30 (s, 3 H,
ꢀOAc), 2.38 (s, 3 H, ArAc), 3.95 (dd, 2 H,
J
5%,6%a=J5%%,6%%a 2.2, J6%a,6%b=J6%%a,6%%b 12.5 Hz, H-
6a%,6%%a), 4.03 (ddd, 2 H, J5%,6%a=J5%%,6%%a 2.2,
5%,6%b=J5%%,6%%b 5.1, J4%,5%=J4%%,5%% 9.8 Hz, H-5%,5%%),
J
4.14 (dd, 2 H, J5%,6%b=J5%%,6%%b 5.1, J6%a,6%b=J6%%a,6%%b
12.5 Hz, H-6%b,6%%b), 4.75* (d, 2 H, J1%,2%=J1%%,2%%
9.5Hz, H-1%,1%%), 5.00 (t, 2 H, J3%,4%=J3%%,4%%
=
J4%,5%=J4%%,5%% 9.8 Hz, H-4%,4%%), 5.33 (dd, 2 H,
J2%,3%=J2%%,3%% 9.5, J3%,4%=J3%%,4%% 9.8 Hz, H-3%,3%%),
5.55 (t, 2 H, J1%,2%=J1%%,2%%=J2%,3%=J2%%,3%% 9.5 Hz,
H-2%,2%%). The (*) indicates a broad peak. 13C
NMR (CDCl3): l 20.1, 20.3, 20.58, 20.62,
20.67, 20.68, 20.8, 20.9, 21.08, 21.13 (ꢀOAc),
29.9 (ArAc), 61.6 (C-6%), 61.8 (C-6%%), 68.0
(C-4%,4%%), 69.4 (C-2%%), 70.0 (C-2%), 73.0 (C-1%%),
73.6 (C-1%), 74.4 (C-3%), 74.5 (C-3%%), 76.9 (C-
5%), 77.1 (C-5%%), 119.6 (C-5), 121.7 (C-3), 128.7
(C-1), 146.4 (C-6) 148.4 (C-2), 150.8 (C-4)
167.3, 167.6, 168.1, 169.2, 169.5, 169.8, 170.22,
170.28, 170.41, 170.44 (ꢀOAc), 197.4 (ArAc);
FABMS (positive ion): m/z 955 [M+H]+.
Anal. Calcd for C42H50O25: C, 52.83; H, 5.28.
Found: C, 53.00; H, 5.31.
13
cates broad peaks. C NMR (CDCl3): l 20.3,
20.59, 20.65, 20.7, 20.9*, 21.0, 21.2* (ꢀOAc),
30.7*, 30.9* (ArAc), 61.9* (C-6%), 68.0 (C-4%),
69.7*, 70.0* (C-2%), 72.8 (C-1%), 74.5* (C-3%),
76.7* (C-5%), 115.4*, 116.9* (C-5), 118.8*,
119.2* (C-3), 125.7*, 127.2* (C-1), 146.5*,
147.8*, 148.0*, 148.2*, 149.8*, 151.3* (C-
2,4,6), 167.6*, 167.7*, 167.8*, 168.0, 168.3,
169.3*, 169.5, 170.3, 170.5 (ꢀOAc), 197.2*,
197.7*(ArAc). The (*) indicates broad peaks,
and C-2, -4, and -6 may be interchanged.
EIMS: m/z 624 [M]+. Anal. Calcd for
C28H32O16: C, 53.85; H, 5.16. Found: C, 53.61;
H, 5.16.
Physicochemical data for (4a): mp 137–
139 °C; [h]2D5 −21° (c 1.0, CHCl3); Rf 0.10 (1:1
hexane–EtOAc); IR (KBr): w 2943, 1784,
1759, 1707, 1597, 1435, 1371, 1230, 1171,
2,4,6-Tri-acetoxyacetophenone (2), 2,4,6-tri-
acetoxy-3-C-(3,4,6-tri-O-acetyl-2-deoxy-i- -
D
arabino-hexopyranosyl)acetophenone (3b), and
2,4,6-tri-acetoxy-3,5-bis-C-(3,4,6-tri-O-acetyl-
1
1142, 1090, 1055, 1036, 903, 874 cm−1; H
2 - deoxy - i -
D
- arabino-hexopyranosyl)aceto-
NMR (CDCl3): l 1.73 (s, 3 H, ꢀOAc), 1.93 (s,
3 H, ꢀOAc), 2.01 (s, 3 H, ꢀOAc), 2.032 (s, 6
H, ꢀOAc), 2.038 (s, 3 H, ꢀOAc), 2.043 (s, 3 H,
ꢀOAc), 2.09 (s, 3 H, ꢀOAc), 2.30 (s, 3 H,
ꢀOAc), 2.37 (s, 3 H, ꢀOAc), 2.41 (s, 3 H,
ArAc), 2.46 (s, 3 H, ꢀOAc), 3.62 (ddd, 1 H,
J5%,6%a 1.5, J5%,6%b 4.9, J4%,5% 9.8 Hz, H-5%), 3.78
(ddd, 1 H, J5%%,6%%a 1.5, J5%%,6%%b 4.9, J4%%,5%% 9.8 Hz,
phenone (4b).—The reaction conditions, post-
treatment, and isolation were carried out in
the same manner as described above. Recrys-
tallization of crude compound 4b from hex-
ane–Et2O gave an analytically pure sample.
Physicochemical data for (3b): mp 132–
133 °C; [h]2D5 −14° (c 1.0, CHCl3); Rf 0.29 (1:1
hexane–EtOAc); IR (KBr): w 3103, 3064,

212
T. Kumazawa et al. / Carbohydrate Research 334 (2001) 207–213
2.003 (s, 6 H, ꢀOAc), 2.37 (s, 6 H, ꢀOAc), 2.40
(s, 3 H, ArAc), 2.50 (s, 3 H, ꢀOAc), 3.88 (br.
s, 2 H, H-5%,5%%), 3.89 (dd, 2 H, J5%,6%a=J5%%,6%%a
2.0, J6%a,6%b=J6%%a,6%%b 12.9 Hz, H-6%a,6%%a), 4.36
(br. s, 2 H, H-6%b,6%%b), 4.92 (m, 2 H, H-1%,1%%),
5.01 (t, 2 H, J3%,4%=J3%%,4%%=J4%,5%=J4%%,5%% 9.8 Hz,
H-4%,4%%), 5.19 (m, 2 H, H-3%,3%%). The H-2%, and
H-2%% peaks are very broad and not identified.
13C NMR (CDCl3): l 20.7, 20.80, 20.84, 20.92,
20.94 (ꢀOAc), 30.5 (ArAc), 34.1* (C-2%,2%%),
62.2 (C-6%,6%%), 68.7* (C-4%,4%%), 71.9* (C-3%,3%%),
77.2 (C-5%,5%%), 124.2* (C-3,5), 129.6 (C-1),
145.8* (C-2,6), 147.8 (C-4), 168.2, 168.3,
169.8, 170.4, 170.5 (ꢀOAc), 197.8 (ArAc). The
(*) indicates broad peaks, and the C-1% and
C-1%% peaks appear broad around 73 ppm in
3024, 2995, 2972, 2962, 2943, 2904, 2893,
1770, 1743, 1695, 1618, 1437, 1371, 1254,
1219, 1190, 1151, 1113, 1066, 1053, 1012, 920,
1
906, 881 cm−1; H NMR (CDCl3): l 2.03 (s, 3
H, ꢀOAc), 2.04 (s, 3 H, ꢀOAc), 2.06 (s, 3 H,
6%-OAc), 2.14 (ddd, 1 H, J1%,2%eq 2.2, J2%eq,3% 5.4,
Jgem 13.2 Hz, H-2%eq), 2.28 (s, 3 H, 6-OAc),
2.31 (s, 3 H, 2-OAc), 2.34 (ddd, 1 H, J2%ax,3%
11.2, J1%,2%ax 12.0, Jgem 13.2 Hz, H-2%ax), 2.37 (s,
3 H, 4-OAc), 2.45 (s, 3 H, ArAc), 3.66 (ddd, 1
H, J=J5%,6%a 2.0, J5%,6%b 4.6, J4%,5% 9.8 Hz, H-5%),
3.94 (dd, 1 H, J5%,6%a 2.0, Jgem 12.5 Hz, H-6%a),
4.43 (dd, 1 H, J5%,6%b 4.6, Jgem 12.5 Hz, H-6%b),
4.66 (dd, 1 H, J1%,2%eq 2.2, J1%,2%ax 12.0 Hz, H-1%),
5.03 (dd, 1 H, J3%,4% 9.3, J4%,5% 9.8 Hz, H-4%), 5.10
(ddd, 1 H, J2%eq,3% 5.4, J3%,4% 9.3, J2%ax,3% 11.2 Hz,
13
13
CDCl3. C NMR (acetone-d6): l 20.71, 20.77,
H-3%), 6.98 (s, 1 H, ArH); C NMR (CDCl3):
20.85, 21.08, 21.12 (ꢀOAc), 30.8 (ArAc),
35.0*, 35.3* (C-2%,2%%), 63.2 (C-6%,6%%), 69.9*
(C-4%,4%%), 72.3* (C-3%,3%%), 72.0*, 73.1* (C-
1%,1%%), 77.3* (C-5%,5%%), 125.6* (C-3,5), 130.7
(C-1), 146.8* (C-2, 6), 149.0 (C-4), 169.0,
169.4, 170.2, 170.4, 170.7 (ꢀOAc), 197.6
(ArAc). The (*) indicates broad peaks, and the
C-1% and C-1%% peaks may be interchanged.
FABMS (positive ion): m/z 839 [M+H]+.
Anal. Calcd for C38H46O21: C, 54.42; H, 5.53.
Found: C, 54.14; H, 5.61.
l 20.71, 20.79, 20.8, 20.9, 21.02, 21.03 (ꢀOAc),
31.0 (ArAc), 34.4 (C-2%), 62.4 (C-6%), 68.9 (C-
4%), 71.5 (C-1%), 71.9 (C-3%), 76.9 (C-5%), 116.3
(C-5), 122.9 (C-3), 126.6 (C-1), 146.2 (C-2),
147.4 (C-6), 149.8 (C-4), 167.8 (6-OAc), 168.2
(2-OAc), 168.5 (4-OAc), 169.9 (ꢀOAc), 170.3
(ꢀOAc), 170.5 (6%-OAc), 197.8 (ArAc); EIMS:
m/z 566 [M]+. Anal. Calcd for C26H30O14: C,
55.12; H, 5.34. Found: C, 55.06; H, 5.34.
Physicochemical data for (4b): mp 113–
115 °C; [h]2D5 −1° (c 0.5, CHCl3); Rf 0.12 (1:1
hexane–EtOAc); IR (KBr): w 2956, 2943,
2877, 1780, 1747, 1705, 1597, 1435, 1369,
1232, 1180, 1107, 1053, 962, 908, 883, 868
References
1
cm−1; H NMR (CDCl3 at 50 °C): l 2.02 (s, 6
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J2%eq,3%=J2%%eq,3%% 5.4, J2%ax,2%eq=J2%%ax,2%%eq 13.3 Hz,
H-2%eq, 2%%eq), 2.30 (s, 6 H, ꢀOAc), 2.304 (ddd,
2 H, J2%ax,3%=J2%%ax,3%% 11.0, J1%,2%ax=J1%%,2%%ax 11.7,
J2%ax,2%eq=J2%%ax,2%%eq 13.3 Hz, H-2%ax, 2%%ax),
2.411* (s, 3 H, ArAc), 2.412* (s, 3 H, ꢀOAc),
3.61 (ddd, 2 H, J5%,6%a=J5%%,6%%a 2.0, J5%,6%b=J5%%,6%%b
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6%a,6%b=J6%%a,6%%b 12.5 Hz, H-6%b,6%%b), 4.54 (dd, 2
H, J1%,2%eq=J1%%,2%%eq 2.0 J1%,2%ax=J1%%,2%%ax 11.7 Hz,
H-1%,1%%), 5.00 (t, 2 H, J3%,4%=J3%%,4%%=J4%,5%
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