Synthesis of C-mannopyranosylphloroacetophenone derivatives and their anomerization

Article abstract of DOI:10.1016/S0008-6215(01)00076-3

The reaction of 2,3,4-tri-O-benzyl-α-L-rhamnopyranosyl fluoride (6-deoxy-2,3,4-tri-O-benzyl-α-L-mannopyranosyl fluoride) with 2,4-dibenzylphloroacetophenone, in the presence of boron trifluoride·diethyl etherate, afforded both the 3-C-α-L- and the 3-C-β-L-rhamnopyranosylphloroacetophenone derivatives. The 3-C-α-L-rhamnoside was produced as a major product, while the 3-C-β-L-rhamnoside was produced as a minor product via anomerization of the 3-C-α-L-rhamnoside. Alternatively, the reaction of 2,3,4,6-tetra-O-benzyl-α-D-mannopyranosyl fluoride with 2,4-di-benzylphloroacetophenone afforded both the 3-C-α-D- and the 3-C-β-D-mannnopyranosylphloroacetophenone derivatives under identical conditions. The 3-C-β-D-mannoside was produced as a major product via anomerization of the 3-C-α-D-mannoside during the reaction. These differences in composition result apparently from the magnitude of the 1,3-diaxial interactions between the C-3 and C-5 positions in these sugar moieties.

Full text of DOI:10.1016/S0008-6215(01)00076-3

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Carbohydrate Research 332 (2001) 103–108
Note
Synthesis of C-mannopyranosylphloroacetophenone
derivatives and their anomerization
Toshihiro Kumazawa,* Shingo Sato, Shigeru Matsuba, Jun-ichi Onodera
Department of Chemistry and Chemical Engineering, Faculty of Engineering, Yamagata Uni6ersity, 4-3-16 Jonan,
Yonezawa, Yamagata 992-8510, Japan
Received 11 December 2000; accepted 1 March 2001
Abstract
The reaction of 2,3,4-tri-O-benzyl-a-
fluoride) with 2,4-dibenzylphloroacetophenone, in the presence of boron trifluoride·diethyl etherate, afforded both
the 3-C-a- - and the 3-C-b- -rhamnopyranosylphloroacetophenone derivatives. The 3-C-a- -rhamnoside was pro-
duced as a major product, while the 3-C-b- -rhamnoside was produced as a minor product via anomerization of the
3-C-a- -rhamnoside. Alternatively, the reaction of 2,3,4,6-tetra-O-benzyl-a- -mannopyranosyl fluoride with 2,4-di-
benzylphloroacetophenone afforded both the 3-C-a- - and the 3-C-b- -mannnopyranosylphloroacetophenone
derivatives under identical conditions. The 3-C-b- -mannoside was produced as a major product via anomerization
of the 3-C-a- -mannoside during the reaction. These differences in composition result apparently from the
L
-rhamnopyranosyl fluoride (6-deoxy-2,3,4-tri-O-benzyl-a-L-mannopyranosyl
L
L
L
L
L
D
D
D
D
D
magnitude of the 1,3-diaxial interactions between the C-3 and C-5 positions in these sugar moieties. © 2001 Elsevier
Science Ltd. All rights reserved.
Keywords: C-Glycosylic compound; C-Glycosylflavonoid; C-Glycoside; C-a-
D
-Mannosyl compound; C-b-D-Mannosyl com-
pound; C-a- -Rhamnosyl compound; C-b- -Rhamnosyl compound; Diaxial interaction; Conformation
L
L
C-Glycosyl flavonoids are plant con-
stituents, some of which have biological activ-
ities.1 In this laboratory, our interests have
been focussed on the synthesis of the glyco-
sylic portion of C-glycosyl flavonoids. Among
previously described the syntheses of a 3-C-b-
-xylopyranosylphloroacetophenone deriva-
D
tive, as well as 3-C-a-
L
- and 3-C-b- -
L
arabinopyranosylphloroacetophenone deriva-
tives, which are important synthetic intermedi-
ates in C-glycosyl flavonoid syntheses. We
the C-glycosyl flavonoids, a C- -rhamnosyl
L
moiety is much less common, comprising only
7% of the sugar moieties in mono-C-glycosyl
flavonoids, and 2% of sugar moieties in di-C-
glycosyl flavonoids.2 In the course of our syn-
thetic study on C-glycosyl flavonoids, we
also described the anomerization of the C-a- -
L
arabinosyl derivative, a reaction which is con-
trolled by diaxial interactions.3 We describe
herein the synthesis of a 3-C-a- -rhamnopyran-
L
osylphloroacetophenone derivative 3, which
is the major product formed initially in the
reaction, and a 3-C-b- -rhamnopyranosyl-
L
* Corresponding author. Tel.: +81-238-263122; fax: +81-
238-263413.
E-mail address: tk111@dip.yz.yamagata-u.ac.jp (T. Ku-
mazawa).
phloroacetophenone derivative 4, which is a
minor product, produced via the anomeriza-
tion of the 3-C-a- -rhamnosyl derivative 3,
L
0008-6215/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0008-6215(01)00076-3

104
T. Kumazawa et al. / Carbohydrate Research 332 (2001) 103–108
derivative 3 was difficult. TLC monitoring
was carried out at reaction temperatures of
−78, −42, −20, 0 °C and ambient tempera-
ture. The bright red–brown spots correspond-
ing to the phenolic constituents of the reaction
mixture were observed by treatment with a 5%
ethanolic ferric chloride. Incidentally, the
prior O-rhamnoside was not colored by the
ethanolic ferric chloride. The colored spot cor-
in the presence of boron trifluoride·diethyl
etherate. We also report the synthesis of a
3-C-a- -mannopyranosylphloroacetophenone
D
derivative 6, which is a minor product formed
initially in the reaction, and a 3-C-b- -
D
mannnopyranosylphloroacetophenone deriva-
tive 7,4a which is a major product, produced
via the anomerization of the 3-C-a- -manno-
D
syl compound 6 under identical conditions. To
compare the magnitude of 1,3-diaxial interac-
tions between the C-3 and C-5 positions in the
responding to the C-b- -rhamnosyl com-
L
pound 4 on the TLC was initially observed at
−20 °C, not at −42 °C. After structural
analysis of compound 3 and 4 by NMR stud-
ies, TLC observation was carried out again, Rf
values of the compounds 3 and 4 were verified
by comparison between the preserved samples
of the reaction mixture at each temperature
sugar moiety, these C-
were synthesized using commercially available
-mannnose, not the commercially unavail-
able -mannose, as a starting glycosyl donor.
D
-mannosyl derivatives
D
L
But the isolation of a C-mannosyl flavonoid
as a natural product from plants has not been
described so far.
1
and these known products. The H NMR
The 3-C-a-
L
-rhamnopyranosylphloroaceto-
spectrum showed that the C-a- -rhamnosyl
L
4
phenone derivative 3 and the 3-C-b-
L
-
compound 3 exists in a C1 conformation, and
1
rhamnopyranosylphloroacetophenone deriva-
tive 4 were synthesized according to methods
previously described.4 The reaction of 2,4-
dibenzylphloroacetophenone 1 with 2,3,4-
the C-b- -rhamnosyl compound 4 had a C4
L
conformation. In previous studies, we re-
ported on the preparation of some C-glyco-
sylphloroacetophenone
derivatives
that
-xy-
tri-O-benzyl-a-
(6-deoxy-2,3,4-tri-O-benzyl-a-
osyl fluoride) 25 in the presence of boron
trifluoride·diethyl etherate gave the 3-C-a-
rhamnoside 3 and the 3-C-b- -rhamnoside 4.
Thin-layer chromatography (TLC) of the re-
-rham-
L
-rhamnopyranosyl fluoride
contain b-
D
-glucosyl,4 b-
D
-galactosyl,4 b-
D
L
-mannopyran-
losyl,3 a-
L
-arabinosyl moieties,3 respectively,
1
as the glycosyl moiety. The H NMR experi-
ments were all conducted at elevated tempera-
tures \100 °C because structural assignment
by NMR spectroscopy at ambient tempera-
ture was hampered by the slow rotation of the
C-1ꢀaglycon bond. In spite of fact that the
L
-
L
action mixture indicated that the C-a-
L
noside 3 was produced via an O“C glycosylic
rearrangement at low temperature and that
C-a- -rhamnosyl compound 3 contains equa-
L
the resulting C-a-
L
-rhamnosyl compound 3
torial substitutions at 1% and 2% positions of the
1
was subsequently anomerized to give the C-b-
rhamnose moiety, the H NMR experiment
L
-rhamnosyl compound 4 by boron tri-
involving the C-a- -rhamnosyl compound 3
L
fluoride·diethyl etherate at temperatures
greater than −20 °C. When the initial tem-
perature of −78 °C was slowly elevated to
could be conducted at ambient temperature.
The 3-C-a- -mannopyranosylphloroace-
tophenone derivative 6 and the 3-C-b-
D
D
-
0 °C, the C-a-
L
-rhamnosyl derivative 3 was
-rhamno-
mannopyranosylphloroacetophenone deriva-
tive 74a were synthesized according to me-
thods previously described.4 The reaction
of 2,4-dibenzylphloroacetophenone 1 with
obtained in 41% yield, and the C-b-
L
syl derivative 4 in 25% yield. When the reac-
tion mixture reached ambient temperature, the
C-a-
L
-rhamnosyl compound 3 was obtained
-rhamnosyl com-
2,3,4,6-tetra-O-benzyl-a-
fluoride 55 in the presence of boron tri-
fluoride·diethyl etherate gave the 3-C-a-
mannosyl compound 6 and the 3-C-b- -man-
nosyl compound 7. TLC of the reaction
-mannosyl
D
-mannopyranosyl
in 40% yield, and the C-b-
L
pound 4 in 27% yield. The yields were deter-
mined after purification using silica-gel
column chromatography. The yield of the C-
D
-
D
a-
acetylation of compound 3, as compound 8,
because purification of the C-a- -rhamnosyl
L
-rhamnosyl derivative 3 was obtained after
mixture indicated that the C-a-
D
compound 6 was produced via an O“C gly-
L
coside rearrangement at low temperature

T. Kumazawa et al. / Carbohydrate Research 332 (2001) 103–108
105
anomeric effect, blocks access to the b-face.
The resulting C-a-glycosyl compounds
adopted the conformation in which the agly-
con is orientated equatorially in order to
avoid unfavorable 1,3-diaxial interactions be-
tween the C-1 and C-3 positions at low tem-
peratures. At elevated temperatures, the
1,3-diaxial interactions between the C-3 and
and that the resulting C-a-
pound 6 then underwent anomerization to
-mannosyl compound 7 by
boron trifluoride·diethyl etherate at tempera-
tures greater than −42 °C. When the initial
temperature of −78 °C was slowly elevated to
D
-mannosyl com-
give the C-b-
D
0 °C, the C-a-
D
-mannosyl compound 6 was
-manno-
obtained in 13% yield, and the C-b-
D
syl compound 7 in 38% yield. When the final
temperature was ambient temperature, the C-
C-5 positions of the C-a-
L
-rhamnosyl com-
-mannosyl compounds 6
pounds 3 and C-a-
D
a-
11% yield, and the C-b-
pound 7 in 28% yield. TLC indicated a slow-
-mannosyl
D
-mannosyl compound 6 was obtained in
led to anomerization in each case by boron
D
-mannosyl com-
trifluoride·diethyl etherate. On comparing the
yields of the C-
those of the C-
L
-rhamnosyl compounds with
-mannosyl compounds at
decomposition of the C-b-
D
D
compound 7 at ambient temperature. The
red–brown colored spot corresponding to the
a final reaction temperature of 0 °C, the 1,3-di-
axial interaction between the C-3 and C-5
C-b-D
-mannosyl compound 7 on the TLC
positions of the C-a-
is weaker than that of the C-a-
compound 6. In fact, the temperature of the
conversion from the C-a- -rhamnosyl com-
pound 3 to the C-b- -rhamnosyl compound 4
is higher than that required for the conversion
of the C-a- -mannosyl compound 6 to the
C-b- -mannosyl compound 7, and the yield
of C-a- -rhamnoside 3 is higher than that of
the C-b- -rhamonosyl compound 4. On the
contrary, the yield of the C-b- -mannosyl
compound 7 is higher than that of the C-a-
-mannosyl compound 6. Compared with
the syntheses of both C- -rhamnosyl and C-
-mannosyl compounds, these facts provide
L
-rhamnosyl compound 3
with ferric chloride was initially observed at
−42 °C, not at −78 °C. After structural
analysis of the compound 6 and 7 by NMR
studies, TLC observation was carried out
again, and Rf values of compounds 6 and 7
were verified by comparison between the pre-
served samples of the reaction mixture at each
temperature and these known products, men-
D
-mannosyl
L
L
D
D
L
1
tioned above. The H NMR spectrum showed
L
that the C-a-
D
-mannosyl compound
6
D
1
adopted the C4 conformation, and that the
C-b- -mannosyl compound 7 was present in
D
4
D
the C1 conformation. As mentioned above,
L
1
the H NMR experiment of C-a- -mannosyl
D
D
compound 6 could be conducted at ambient
temperature.
experimental evidence for the magnitude of
the 1,3-diaxial interaction between the C-3
and C-5 positions in the sugar moieties
(Scheme 1).
Such an anomerization process has been
discussed by Suzuki et al.,6 by Schmidt,7 and
by our group,3 respectively. Lewis acid weak-
ens the C-1ꢀO bond by attack at the tetra-
hydropyran oxygen, which leads to an
open-chain intermediate that could undergo
isomerization and subsequent recyclization.
Recently Yamada and co-workers reported on
the axial-rich conformation derived form diax-
1. Experimental
General methods.—All nonaqueous reac-
tions were carried out under an atmosphere of
dry Ar using freshly distilled solvents, 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. Wakogel C-300® (particle size
0.045–0.075 mm) was used for column chro-
matography. Optical rotations were recorded
ial interactions in the
L
-rhamnopyranosyl ring
and the
D
-mannopyranosyl ring,8 and Suzuki
and co-workers reported that aryl C-a- -
L
4
rhamnosyl compounds prefer the flipped C1
conformation.9
In this study, after the cleavage of the O-
glycoside, a sugar oxonium ion is attacked
from the a-face, because the axial b-benzyloxy
group at the C-2 position, together with the

106
T. Kumazawa et al. / Carbohydrate Research 332 (2001) 103–108
using CHCl3 as solvent on a JASCO DIP-370
digital polarimeter. IR spectra were recorded
on a Horiba FT-200 IR spectrometer as films
on NaCl plates. Mass spectra were recorded
on a JEOL JMS-AX-505-HA mass spectrome-
ter under conditions of fast-atom bombard-
ment (FAB) using 3-nitrobenzyl alcohol as the
layer was washed with water and brine and
then dried over anhyd MgSO4. The solvent
was evaporated in vacuo. The residual syrup
was column chromatographed on silica gel
(5:1 hexane–EtOAc) to give 4 (443 mg, 25%)
as a colorless, highly viscous oil, and pure 3
(12 mg, 0.7%) as a colorless, highly viscous
oil, and a crude fraction of compound 3. The
fraction containing 3 was acetylated using
Ac2O, pyridine, and a catalytic amount of
4,4-dimethylaminopyridine to give the acetyl-
ated compound 8 (737 mg, 40%) as a color-
less, highly viscous oil.
1
matrix. H NMR spectra were recorded on a
Varian Inova 500 instrument using Me4Si as
the internal reference.
4,6-Bis-benzyloxy-2-hydroxy-3-C-(2,3,4-tri-
O-benzyl-h- -rhamnopyranosyl)acetophenone
L
(3), 4,6-bis-benzyloxy-2-hydroxy-3-C-(2,3,4-
tri - O - benzyl - i - - rhamnopyranosyl)aceto-
phenone (4), and 2-acetoxy-4,6-bis-benzyloxy-
3-C-(2,3,4-tri-O-benzyl-h- -rhamnopyranosyl)-
L
Physicochemical data for (3): [h]2D0 −32° (c
1.0, CHCl3); Rf 0.44 (3:1 hexane–EtOAc); IR
(NaCl): 3088, 3062, 3030, 3005, 2968, 2931,
2872, 1622, 1593, 1497, 1454, 1429, 1369,
1273, 1155, 1113, 1028, 912, 795, 737cm−1; 1H
NMR (CDCl3): l 1.39 (d, 3 H, J 6.9 Hz,
H-6%), 2.57 (s, 3 H, ArAc), 3.50 (dd, 1 H, J
3.1, 4.3 Hz, H-4%), 3.97 (dd, 1 H, J 3.2, 4.3 Hz,
H-3%), 4.16 (dq, 1 H, J 3.1, 6.9 Hz, H-5%), 4.36
(d, 1 H, J 12.3 Hz, benzylic CH2), 4.42 (d, 1
H, J 12.3 Hz, benzylic CH2), 4.50 (s, 2 H,
benzylic CH2), 4.53 (d, 1 H, J 12.4 Hz, ben-
zylic CH2), 4.69 (d, 1 H, J 12.4 Hz, benzylic
CH2), 4.73 (dd, 1 H, J 3.2, 9.0 Hz, H-2%), 4.98
(d, 1 H, J 12.1 Hz, benzylic CH2), 5.06 (d, 1
H, J 12.1 Hz, benzylic CH2), 5.07 (s, 2 H,
L
acetophenone (8).—To a stirred mixture of 1
(2.39 g, 6.87 mmol, 3 equiv), 2,3,4-tri-O-ben-
zyl-a- -rhamnopyranosyl fluoride (2, 1.00 g,
L
,
2.29 mmol) and powdered 4 A molecular
sieves (3 g) in CH2Cl2 (30 mL) at −78 °C,
BF3·Et2O (592 mL, 4.81 mmol, 2.1 equiv) was
added dropwise, and the mixture was stirred
for 30 min. The temperature was then allowed
to increase to −42 °C with continued stirring
for 30 min, then to −20 °C with continued
stirring for 30 min, and finally to 0 °C for 1 h.
After adding ice-water, the resulting mixture
was filtered through a Celite® pad. The filtrate
was extracted with CHCl3, and the organic
Scheme 1.

T. Kumazawa et al. / Carbohydrate Research 332 (2001) 103–108
107
H, J 9.8 Hz, H-1%), 6.41 (s, 1 H, ArH), 7.14–
7.40 (m, 25 H, ArH); FABMS (positive-ion):
m/z 807 [M+H]+; FABMS (negative-ion):
m/z 805 [M−H]−. Anal. Calcd for C51H50O9:
C, 75.91; H, 6.25. Found: C, 75.69; H, 5.98.
4,6-Bis-benzyloxy-2-hydroxy-3-C-(2,3,4,6-
benzylic CH2), 5.73 (d, 1 H, J 9.0 Hz, H-1%),
6.02 (s, 1 H, ArH), 7.05–7.42 (m, 25 H, ArH),
14.25 (s, 1 H, ArOH); FABMS (positive-ion):
m/z 765 [M+H]+; FABMS (negative-ion):
m/z 763 [M−H]−. Anal. Calcd for C49H48O8:
C, 76.94; H, 6.32. Found: C, 76.68; H, 6.11.
Physicochemical data for (4): [h]2D0 −39° (c
1.0, CHCl3); Rf 0.53 (3:1 hexane–EtOAc); IR
(NaCl): 3317, 3089, 3063, 3030, 3007, 2974,
2931, 2904, 2873, 1699, 1614, 1533, 1497,
1454, 1368, 1352, 1273, 1163, 1120, 1079,
tetra - O - benzyl - h -
phenone (6) and 4,6-bis-benzyloxy-2-hydroxy-
3-C-(2,3,4,6-tetra-O-benzyl-i- -mannopyran-
D
- mannopyranosyl)aceto-
D
osyl)acetophenone (7).—The reaction condi-
tions, post-treatment and isolation were car-
ried out in the same manner as described
above. An analytically pure sample of com-
pound 6 was obtained by HPLC.
1
1028, 912, 797, 750, 735 cm−1; H NMR
(CDCl3): l 1.38 (d, 3 H, J 6.1 Hz, H-6%), 2.53
(s, 3 H, ArAc), 3.45 (dq, 1 H, J 6.1, 9.3 Hz,
H-5%), 3.63 (dd, 1 H, J 2.9, 9.3 Hz, H-3%), 3.72
(t, 1 H, J 9.3 Hz, H-4%), 3.98 (dd, 1 H, J 1.1,
2.9 Hz, H-2%), 4.40 (d, 1 H, J 11.7 Hz, benzylic
CH2), 4.56 (d, 1 H, J 11.8 Hz, benzylic CH2),
4.63 (d, 1 H, J 11.8 Hz, benzylic CH2), 4.66
(d, 1 H, J 11.7 Hz, benzylic CH2), 4.67 (d, 1
H, J 10.9 Hz, benzylic CH2), 4.80 (d, 1 H, J
11.6 Hz, benzylic CH2), 4.83 (d, 1 H, J 11.6
Hz, benzylic CH2), 4.91 (d, 1 H, J 1.1 Hz,
H-1%), 4.96 (d, 1 H, J 10.9 Hz, benzylic CH2),
5.06 (d, 1 H, J 11.9 Hz, benzylic CH2), 5.08
(d, 1 H, J 11.9 Hz, benzylic CH2), 5.98 (s, 1 H,
ArH), 7.03–7.41 (m, 25 H, ArH), 11.02 (br.,s,
1 H, ArOH); FABMS (positive-ion): m/z 765
[M+H]+; FABMS (negative-ion): m/z 763
[M−H]−. Anal. Calcd for C49H48O8: C,
76.94; H, 6.32. Found: C, 76.68; H, 6.16.
Physicochemical data for (8): [h]2D0 +34° (c
1.0, CHCl3); Rf 0.40 (3:1 hexane–EtOAc); IR
(NaCl): 3088, 3062, 3030, 3007, 2968, 2931,
2873, 1770, 1693, 1605, 1585, 1497, 1454,
1369, 1350, 1319, 1250, 1203, 1155, 1092,
Physicochemical data for (6): [h]2D0 +20° (c
1.0, CHCl3); Rf 0.46 (3:1 hexane–EtOAc); IR
(NaCl): 3088, 3063, 3030, 3007, 2929, 2864,
1621, 1593, 1497, 1454, 1429, 1367, 1271,
1169, 1113, 1097, 1028, 1003, 910, 797, 737
1
cm−1; H NMR (CDCl3): l 2.57 (s, 3 H,
ArAc), 3.73 (dd, 1 H, J 2.4, 4.3 Hz, H-4%), 3.78
(dd, 1 H, J 6.2, 10.2 Hz, H-6%a), 3.88 (dd, 1 H,
J 6.9, 10.2 Hz, H-6%b), 3.93 (dd, 1 H, J 3.1, 4.3
Hz, H-3%), 4.23 (ddd, 1 H, J 2.4, 6.2, 6.9 Hz,
H-5%), 4.34 (d, 1 H, J 12.2 Hz, benzylic CH2),
4.36 (d, 1 H, J 12.3 Hz, benzylic CH2), 4.39
(d, 1 H, J 12.2 Hz, benzylic CH2), 4.46 (d, 1
H, J 12.4 Hz, benzylic CH2), 4.47 (d, 2 H, J
12.3 Hz, benzylic CH2), 4.51 (d, 1 H, J 12.4
Hz, benzylic CH2), 4.62 (d, 1 H, J 12.3 Hz,
benzylic CH2), 4.76 (dd, 1 H, J 3.1, 9.3 Hz,
H-2%), 4.94 (d, 1 H, J 12.0 Hz, benzylic CH2),
5.05 (d, 1 H, J 12.0 Hz, benzylic CH2), 5.07
(d, 1 H, J 12.4 Hz, benzylic CH2), 5.09 (d, 1
H, J 12.4 Hz, benzylic CH2), 5.68 (d, 1 H, J
9.3 Hz, H-1%), 6.02 (s, 1 H, ArH), ꢀ7.06–7.43
(m, 30 H, ArH), 14.28 (s, 1 H, ArOH);
FABMS (positive-ion): m/z 871 [M+H]+;
FABMS (negative-ion): m/z 869 [M−H]−.
Anal. Calcd for C56H54O9: C, 77.22; H, 6.25.
Found: C, 77.25; H, 6.24.
1
1028, 914, 885, 810, 739 cm−1; H NMR
(CDCl3): l 1.40 (d, 3 H, J 7.1 Hz, H-6%), 2.03
(s, 3 H, ArOAc), 2.46 (s, 3 H, ArAc), 3.45 (dd,
1 H, J 1.3, 3.8 Hz, H-4%), 3.93 (dd, 1 H, J 2.9,
3.8 Hz, H-3%), 4.07 (dq, 1 H, J 1.3, 7.1 Hz,
H-5%), 4.31 (d, 1 H, J 12.2 Hz, benzylic CH2),
4.34 (d, 1 H, J 12.2 Hz, benzylic CH2), 4.37
(d, 1 H, J 11.7 Hz, benzylic CH2), 4.41 (d, 1
H, J 11.7 Hz, benzylic CH2), 4.45 (dd, 1 H, J
2.9, 9.8 Hz, H-2%), 4.57 (d, 1 H, J 12.2 Hz,
benzylic CH2), 4.78 (d, 1 H, J 12.2 Hz, ben-
zylic CH2), 4.96 (d, 1 H, J 12.0 Hz, benzylic
CH2), 5.02 (d, 1 H, J 12.0 Hz, benzylic CH2),
5.05 (d, 1 H, J 12.1 Hz, benzylic CH2), 5.07
(d, 1 H, J 12.1 Hz, benzylic CH2), 5.70 (d, 1
References
1. (a) Waiss, Jr., A. C.; Chan, B. G.; Elliger, C. A.; Wiseman,
B. R.; McMillian, W. W.; Widstrom, N. W.; Zuber, M. S.;
Keaster, A. J. J. Econ. Entomol. 1979, 72, 256–258;
(b) Elliger, C. A.; Chan, B. G.; Waiss, Jr., A. C.; Lundin,
R. E.; Haddon, W. F. Phytochemistry 1980, 19, 293–297;
(c) Catarte, B. K.; Carr, S.; DeBrosse, C.; Hemling, M. E.;
Mackenzie, L.; Offen, P.; Berry, D. E. Tetrahedron 1991,
47, 1815–1821;

108
T. Kumazawa et al. / Carbohydrate Research 332 (2001) 103–108
K. K.; Unnikrishnan, M. K. Radiat. Res. 2000, 154,
(d) Snook, M. E.; Gueldner, R. C.; Widstrom, N. W.;
455–460.
Wiseman, B. R.; Himmelsbach, D. S.; Harwood, H. S.;
Costello, C. E. J. Agric. Food Chem. 1993, 41, 1481–1485;
(e) Besson, E.; Dellamonica, G.; Chopin, J.; Markham, K.
R.; Kim, M.; Koh, H.-S.; Fukami, H. Phytochemistry
1985, 24, 1061–1064;
(f) Bohm, K. H.; Lotter, H.; Seligmann, O.; Wagner, H.
Planta Med. 1992, 58, 544–548;
(g) Matsubara, Y.; Sawabe, A. J. Synth. Org. Chem. Jpn.
1994, 52, 318–327; Chem. Abstr. 1994, 120, 319319j;
(h) Hutter, J. A.; Salman, M.; Stavinoha, W. B.; Satsangi,
N.; Williams, R. F.; Streeper, R. T.; Weintraub, S. T. J.
Nat. Prod. 1996, 59, 541–543;
(i) Okamura, N.; Hine, N.; Harada, S.; Fujioka, T.; Mi-
hashi, K.; Yagi, A. Phytochemistry 1996, 43, 495–498;
(j) Haribal, M.; Renwick, J. A. A. Phytochemistry 1998,
47, 1237–1240;
(k) Markham, K. R.; Tanner, G. J.; Lit, M.-C.; White-
cross, M. I.; Nayudu, M.; Mitchell, K. A. Phytochemistry
1998, 49, 1913–1919;
(l) Ju, Y.; Sacalis, J. N.; Still, C. C. J. Agric. Food Chem.
1998, 46, 3785–3788;
(m) Afifi, F. U.; Khalil, E.; Abdalla, S. J. Ethnopharmacol.
1999, 65, 173–177;
(n) Deci, P. U.; Ganasoundari, A.; Vrinda, B.; Srinivasan,
2. Jay, M. In The Fla6onoids: Ad6ances in Research Since
1986; Harborne, J. B., Ed.; Chapman and Hall: London,
1994; pp. 57–93.
3. Kumazawa, T.; Saito, T.; Matsuba, S.; Sato, S.; Onodera,
J. Carbohydr. Res. 2000, 329, 855–859.
4. (a) Kumazawa, T.; Akutsu, Y.; Matsuba, S.; Sato, S.;
Onodera, J. Carbohydr. Res. 1999, 320, 129–137;
(b) Kumazawa, T.; Chiba, M.; Matsuba, S.; Sato, S.;
Onodera, J. Carbohydr. Res. 2000, 328, 599–603.
5. Hayashi, M.; Hashimoto, S.; Noyori, R. Chem. Lett. 1984,
1747–1750.
6. (a) Hosoya, T.; Takashiro, E.; Matsumoto, T.; Suzuki, K.
J. Am. Chem. Soc. 1994, 116, 1004–1015;
(b) Hosoya, T.; Takashiro, E.; Matsumoto, T.; Suzuki, K.
Tetrahedron Lett. 1994, 35, 4591–4594;
(c) Hosoya, T.; Ohashi, Y.; Matsumoto, T.; Suzuki, K.
Tetrahedron Lett. 1996, 37, 663–666.
7. (a) Schmidt, B.; J. Chem. Soc., Perkin Trans. 1 1999,
2627–2637;
(b) Schmidt, B. Org. Lett. 2000, 2, 791–794.
8. Yamada, H.; Nakatani, M.; Ikeda, T.; Marumoto, Y.
Tetrahedron Lett. 1999, 40, 5573–5576.
9. Matsumoto, T.; Katsuki, M.; Suzuki, K. Tetrahedron Lett.
1989, 30, 833–836.
.
.