A practical synthesis of β-D-GlcA-(1→3)-β-D-Gal-(1→3)-β-D-Gal-(1→4)-D- Xyl, a part of the common linkage region of a glycosaminoglycan

Article abstract of DOI:10.1016/S0008-6215(02)00169-6

A practical synthesis of β-D-GlcA-(1→3)-β-D-Gal-(1→3)-β-D-Gal-(1→4)- β-D-Xyl-(1→OMe) was achieved by coupling of methyl 2,3,4-tri-O-acetyl-α-D-glucopyranosyluronate trichloroacetimidate with a trisaccharide acceptor. The trisaccharide acceptor was obtained by condensation of 3-O-allyl-2,4,6-tri-O-benzoyl-β-D-galactopyranosyl-(1→3)-2,4,6- tri-O-benzoyl-α-D-galactopyranosyl trichloroacetimidate with methyl 2,3-di-O-benzoyl-β-D-xylopyranoside, followed by deallylation. The β-(1→3)-linked disaccharide was prepared readily with p-methoxyphenyl 3-O-allyl-2,4,6-tri-O-benzoyl-β-D-galactopyranoside as the key synthon. The α-(1→3)-linkage was formed in considerable amount with galactose mono- and disaccharide trichloroacetimidate donors with C-2 neighboring group participation.

Full text of DOI:10.1016/S0008-6215(02)00169-6

Carbohydrate Research 337 (2002) 1373–1380
www.elsevier.com/locate/carres
A practical synthesis of
b-
D
-GlcA-(1“3)-b-
D
-Gal-(1“3)-b-
D
-Gal-(1“4)-
D
-Xyl, a part of
the common linkage region of a glycosaminoglycan
Langqiu Chen, Fanzuo Kong*
Research Center for Eco-En6ironmental Sciences, Chinese Academy of Sciences, P. O. Box 2871, Beijing 100085, China
Received 8 April 2002; accepted 8 May 2002
Abstract
A practical synthesis of b-
methyl 2,3,4-tri-O-acetyl-a- -glucopyranosyluronate trichloroacetimidate with a trisaccharide acceptor. The trisaccharide acceptor
was obtained by condensation of 3-O-allyl-2,4,6-tri-O-benzoyl-b- -galactopyranosyl-(1“3)-2,4,6-tri-O-benzoyl-a- -galactopy-
ranosyl trichloroacetimidate with methyl 2,3-di-O-benzoyl-b- -xylopyranoside, followed by deallylation. The b-(1“3)-linked
-galactopyranoside as the key synthon.
D
-GlcA-(1“3)-b-
D
-Gal-(1“3)-b-
D
-Gal-(1“4)-b-D-Xyl-(1“OMe) was achieved by coupling of
D
D
D
D
disaccharide was prepared readily with p-methoxyphenyl 3-O-allyl-2,4,6-tri-O-benzoyl-b-
D
The a-(1“3)-linkage was formed in considerable amount with galactose mono- and disaccharide trichloroacetimidate donors with
C-2 neighboring group participation. © 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Oligosaccharide; Proteoglycan; Trichloroacetimidate
1. Introduction
glycosyl orthoester as the intermediates. Earlier, synthe-
sis of some complex oligosaccharides containing the
tetrasaccharide moiety was also reported.7 In these
syntheses, orthogonal masking groups and multiple
steps were needed. We tried to find a practical method
for the synthesis of the tetrasaccharide. As outlined in
Scheme 1, our synthesis started from p-methoxyphenyl
Proteoglycans are biologically ubiquitous glycosyl-
ated glycoprotein conjugates with widely varying roles1
such as in lubrication,2 blood anticoagulation,3 and
light transmission.4 Several different proteoglycans
have in common a highly conserved tetrasaccharide
linkage region joining a glycosaminoglycan to a core
protein. The tetrasaccharide is considered to be a
biosynthetic intermediate of an immature glycosamino-
glycan chain.5 For a study of structure–function rela-
tionship of oligosaccharides, we present herein a
practical method for the synthesis of the linkage region
tetrasaccharide.
2,3,4,6-tetra-O-acetyl-b- -galactopyranoside (1), which
D
was obtained by the method used for the preparation of
the corresponding mannose analogue.8 Deacetylation of
1, 3-selective allylation through a dibutyltin complex,9
followed by benzoylation, afforded p-methoxyphenyl
3-O-allyl-2,4,6-tri-O-benzoyl-b-D-galactopyranoside
(2). Compound 2 was easily converted to either a donor
10
or an acceptor. Its deallylation with PdCl2 gave the
acceptor 4, while its oxidative cleavage of 1-OMP with
CAN followed by trichloroacetimidation11 furnished
the donor 3. Glycosylation of 4 with 3 in the presence
of catalytic TMSOTf gave the required b-linked disac-
charide 5 as the major product (54%) together with the
a-linked isomer 6 as the minor one (31%). Since the
a-linkage product was produced in a considerable
amount, this coupling was abnormal and contradictory
2. Results and discussion
Recently, the tetrasaccharide serine conjugate was
synthesized by Allen and Fraser-Reid6 with pentenyl
* Corresponding author. Tel.: +86-10-62936613; fax: +
86-10-62923563
E-mail address: fzkong@mail.rcees.ac.cn (F. Kong).
0008-6215/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.
PII: S0008-6215(02)00169-6

1374
L. Chen, F. Kong / Carbohydrate Research 337 (2002) 1373–1380
to the conventional rule that a 1,2-trans linkage can be
obtained solely with the donor with C-2 neighboring
group participation.12 This abnormality was similar to
that in the coupling of the corresponding glucose donor
and acceptor analogues that gave predominant a-(1“
3)-linkages.13 The disaccharide 5, as the inner moiety of
the target tetrasaccharide, was readily transformed to
the disaccharide donor 7 by oxidative cleavage of 1-
OMP, followed by trichloroacetimidation. The xyloside
acceptor 10 was prepared by deacetylation of 8, then
selective chloroacetylation14 of the resultant methyl b-
lowed by dechloroacetylation. Condensation of 7 with
10 yielded equivalent b-linked trisaccharide 11 (40%)
and a-linked trisaccharide 12 (40%). Here, it gave ab-
normal coupling again with the b-(1“3)-linked disac-
charide as the donor with a C-2 ester group, and this
result was also similar to that in the coupling with
b-(1“3)-linked glucodisaccharide donor analogue.13
Deallylation of 11 produced the trisaccharide acceptor
13, and subsequent coupling with 14 gave the required
tetrasaccharide 18 (31%), together with the a-linked
isomer 19 (31%). Alternatively, the nonreducing trisac-
charide was built first, then transformed to a donor,
D
-xylopyranoside, and subsequent benzoylation, fol-
Scheme 1. Reagents and conditions: (a) i. MeONaꢀMeOH; ii. MeOH, Bu2SnO, then AllBr, Bu4NI, toluene; iii. PhCOCl, pyr, rt.
(b) i. CH3CNꢀH2O, CAN; ii. CCl3CN, CH2Cl2, K2CO3, rt; (c) PdCl2, CH3OH, 40 °C; (d) TMSOTf, CH2Cl2, −25 °C to rt; (e)
i. MeONaꢀMeOH; ii. benzene, Bu2SnO, then ClCH2COCl; iii. PhCOCl, Pyr, rt; (f) thiourea, EtOH, CH2Cl2, reflux; (g)
NaOHꢀCH3OHꢀH2O, rt.

L. Chen, F. Kong / Carbohydrate Research 337 (2002) 1373–1380
1375
and coupled with 10. Thus, the disaccharide acceptor
methoxyphenyl
2,3,4,6-tetra-O-acetyl-b-
D
-galactopy-
15 was obtained by deallylation of 5, and subsequent
condensation of 15 with 14 furnished 16 as the major
product (55%). Oxidative cleavage of 1-OMP of 16, and
subsequent trichloroacetimidation gave the trisaccha-
ride donor 17, and then condensation with 10 gave 18
as the major product (40%). The latter route was more
effective since it minimized the a-isomer formation.
Finally, conventional deprotection offered the tetra-
saccharide as its methyl glycoside sodium salt. Al-
though some coupling reactions described above gave
anomeric mixtures, the anomers were readily separated
in sufficient quantities to complete the synthetic
sequences.
ranoside (1) (9.08 g, 20.0 mmol) in MeOH (100 mL)
was added 4.0 M NaOMe–MeOH solution dropwise to
pH 10. After stirring the mixture at rt for 5 h, TLC
(EtOAc) indicated that the reaction was complete. The
reaction mixture was neutralized with 1:10 HOAc–
MeOH, then the mixture was concentrated, and the
residue was purified by column chromatography (3:1
EtOH–MeOH) to give a solid. To a solution of the
solid in MeOH (200 mL) was added Bu2SnO (5.22 g,
21.0 mmol), and the mixture was heated under reflux
for 2 h, then concentrated to dryness. The residue was
diluted with toluene (200 mL), and then allyl bromide
(17.1 mL, 200 mmol), Bu4NI (7.38 g, 20.0 mmol) were
added to the mixture. The reaction was carried out at
60 °C for 24 h, at which time TLC (EtOAc) indicated
that the reaction was complete. The reaction mixture
was concentrated, and the residue was diluted with
CH2Cl2 (20 mL). To the mixture were added pyridine (8
mL) and BzCl (7.18 mL, 62.0 mmol). The mixture was
stirred overnight at rt, at which time TLC (3:1
petroleum ether–EtOAc) indicated that the reaction
was complete. The mixture was diluted with CH2Cl2
and washed with 1 N HCl, water, and satd aq
NaHCO3. The organic layer was combined, dried, and
concentrated. Purification of the crude product by
column chromatography (3:1 petroleum ether–EtOAc)
gave 2 as a syrup (9.19 g, 72%): [h]D +69.3° (c 1.0,
CHCl3); 1H NMR (CDCl3): l 8.19–7.45 (m, 15 H,
PhH), 6.94 (d, 2 H, J 9.1 Hz, CH3OC6H4Oꢀ), 6.64 (d,
2 H, J 9.1 Hz, CH3OC6H4Oꢀ), 5.87 (dd, 1 H, J3,4 3.5
Hz, H-4), 5.76 (dd, 1 H, J2,3 10.0 Hz, H-2), 5.66 (m, 1
In summary, we present herein a practical synthesis
of b-D
-GlcA-(1“3)-b-
D
-Gal-(1“3)-b-
D
-Gal-(1“4)-D-
Xyl. It should be possible to carry out a large-scale
preparation of the tetraose by employing this method.
In the preparation of (1“3)-linked galactobiose with a
galactose donor or in the preparation of trisaccharides
with b-(1“3)-linked galactobiose as the donor, the
a-linkage can be produced even with C-2 neighboring
group participation.
3. Experimental
General methods.—Melting points were determined
with a ‘Mel-Temp’ apparatus. Optical rotations were
determined with a Perkin–Elmer model 241-MC auto-
matic polarimeter for solutions in a 1-dm, jacketed cell.
1H NMR spectra were recorded with Varian XL-400
and Varian XL-200 spectrometers, for solutions in
CDCl3 with tetramethylsilane (Me4Si) as the internal
standard or for solutions in D2O with acetone as the
internal standard. Mass spectra were recorded with a
Shimadzu LCMS-2010 mass spectrometer using the
negative-ion electrospray-ionization mode. The pro-
gress of all reactions was followed by thin-layer chro-
matography (TLC) that was performed on silica gel HF
with detection by charring with 30% (v/v) sulfuric acid
in methanol or by UV detection. Column chromatogra-
phy was conducted by elution of a column (8×100
mm, 16×240 mm, 18×300 mm, 35×400 mm) of
silica gel (100–200 mesh) and EtOAc–petroleum ether
(bp 60–90 °C) as the eluent. Analytical LC was per-
formed with a Gilson HPLC consisting of a pump
(model 306), stainless steel column packed with silica
gel (Spherisorb SiO2, 10×300 mm or 4.6×250 mm),
differential refractometer (132-RI Detector) and UV/vis
detector (model 118). EtOAc–petroleum ether (bp 60–
90 °C) was used as the eluent at a flow rate of 1–4
mL/min. Solutions were concentrated at a temperature
B60 °C under diminished pressure.
H,
CH2ꢁCHꢀCH2O),
5.21–5.05
(m,
2
H,
CH2ꢁCHꢀCH2O), 5.09 (d, 1 H, J1,2 8.1 Hz, H-1),
4.62–4.54 (m, 2 H, H-6, H-6%), 4.25 (m, 1 H, H-5),
4.19–3.98 (m, 2 H, CH2ꢁCHꢀCH2O), 3.91 (dd, 1 H,
H-3), 3.71 (s, 3 H, CH3O). Anal. Calcd for C37H34O10:
C, 69.59; H, 5.33. Found: C, 69.89; H, 5.31
3-O-Allyl-2,4,6-tri-O-benzoyl-i-
trichloroacetimidate (3b) and 3-O-allyl-2,4,6-tri-O-ben-
zoyl-h- -galactopyranosyl trichloroacetimidate (3a).—
To a solution of 2 (12.76 g, 20.0 mmol) in 4:1
CH3CN–H2O (250 mL) was added CAN
D-galactopyranosyl
D
[(NH4)2Ce(NO3)6, 43.86 g, 80.0 mmol], and the mixture
was stirred at rt for 30 min, at the end of which time
TLC (2:1 petroleum ether–EtOAc) indicated that the
reaction was complete. The mixture was extracted with
EtOAc and washed with water. The organic layer was
concentrated under reduced pressure, and the crude
product was purified by column chromatography (2:1
petroleum ether–EtOAc) to afford a solid. To a solu-
tion of the solid in CH2Cl2 (100 mL) were added
trichloroacetonitrile (3.5 mL) and anhyd potassium car-
bonate (11.50 g). The reaction mixture was stirred
overnight at rt and then filtered, and the filtrate was
concentrated in vacuo. The residue was purified by
p-Methoxyphenyl 3-O-allyl-2,4,6-tri-O-benzoyl-i-
D-
galactopyranoside (2).—To solution of p-
a

1376
L. Chen, F. Kong / Carbohydrate Research 337 (2002) 1373–1380
column chromatography (3:1 petroleum ether–EtOAc)
to give 3b (8.25 g, 61%) and 3a (2.03 g, 15%), respec-
tively, as syrups: 3b: [h]D +192.4° (c 0.9, CHCl3); H
8.19–7.15 (m, 30 H, PhH), 6.81 (d, 2 H, J 9.1 Hz,
CH3OC6H4Oꢀ), 6.53 (d, 2 H, J 9.1 Hz, CH3OC6H4Oꢀ),
5.98 (d, 1 H, J3,4 3.7 Hz, H-4II), 5.82 (dd, 1 H, J1,2 7.8
Hz, J2,3 9.8 Hz, H-2II), 5.71 (d, 1 H, J3,4=3.0 Hz,
H-4I), 5.47 (m, 1 H, CH2ꢁCHꢀCH2O), 5.28 (dd, 1 H,
J1,2 7.8 Hz, J2,3=8.1 Hz, H-2I), 5.02–4.89 (m, 2 H,
CH2ꢁCHꢀCH2O), 4.97 (d, 1 H, H-1II), 4.89 (d, 1 H,
H-1I), 4.65–4.60 (m, 2 H), 4.47 (dd, 1 H, J5,6 8.5 Hz,
J6,6% 11.8 Hz, H-6), 4.30 (dd, 1 H, J5,6 6.3 Hz, J6,6% 11.5
Hz, H-6), 4.25 (dd, 1 H, H-3II), 4.16 (dd, 1 H), 4.08 (m,
1 H, H-5), 4.02–3.78 (m, 2 H, CH2ꢁCHꢀCH2O), 3.67
(dd, 1 H, H-3I) 3.65 (s, 3 H, CH3O). 13C NMR
(CDCl3): l 165.71, 165.57, 165.57, 165.22, 164.11,
164.06 (PhCO), 155.00, 150.79 (CH3OC6H4Oꢀ), 133.49,
132.88, 132.75, 132.43, 132.02, 129.80, 129.56, 129.34,
129.20, 129.04, 128.97, 128.85, 128.78, 128.22, 128.12,
128.07, 128.04, 127.97, 127.78, 127.55, 118.27
(CH3OC6H4Oꢀ), 117.13 (CH2ꢁCHꢀCH2O), 113.81
(CH3OC6H4Oꢀ), 101.31, 100.57 (C-1), 77.15, 75.83,
71.78, 70.78, 70.86, 70.70, 70.11, 69.75, 66.10, 62.78,
61.87, 55.06 (CH3O). Anal. Calcd for C64H56O18: C,
1
NMR (400 MHz, CDCl3): l 8.65 (s, 1 H, NH), 8.18–
7.43 (m, 15 H, PhH), 6.06 (d, 1 H, J1,2 8.1 Hz, H-1),
5.92 (dd, 1 H, J3,4 3.4 Hz, J4,5 1.3 Hz, H-4), 5.79 (dd, 1
H, J2,3 9.8 Hz, H-2), 5.68 (m, 1 H, CH2ꢁCHꢀCH2O),
5.21–5.06 (m, 2 H, CH2ꢁCHꢀCH2O), 4.67 (dd, 1 H, J5,6
6.8 Hz, H-6), 4.46 (dd, 1 H, J5,6% 6.3 Hz, J6,6% 11.4 Hz,
H-6%), 4.35 (m, 1 H, H-5), 4.20–4.00 (m, 2 H,
CH2ꢁCHꢀCH2O), 3.96 (dd, 1 H, H-3). Anal. Calcd for
C32H28Cl3NO9: C, 56.76; H, 4.14. Found: C, 56.49; H,
4.15. 3a: [h]D +124.7° (c 1.0, CHCl3); 1H NMR
(CDCl3): l 8.57 (s, 1 H, NH), 8.15–7.42 (m, 15 H,
PhH), 6.81 (d, 1 H, J1,2 3.7 Hz, H-1), 6.01 (dd, 1 H, J3,4
3.3 Hz, J4,5 1.1 Hz,H-4), 5.79 (m,
1
H,
CH2ꢁCHꢀCH2O), 5.70 (dd, 1 H, J2,3 10.4 Hz, H-2),
5.27–5.10 (m, 2 H, CH2ꢁCHꢀCH2O), 4.68 (m, 1 H,
H-5), 4.54 (dd, 1 H, J5,6 7.1 Hz, H-6), 4.45 (dd, 1 H,
J5,6% 5.5 Hz, J6,6% 11.5 Hz, H-6%), 4.30 (dd, 1 H, H-3),
4.26–4.07 (m, 2 H, CH2ꢁCHꢀCH2O). Anal. Calcd for
C32H28Cl3NO9: C, 56.76; H, 4.14. Found: C, 56.51; H,
4.25.
69.06; H, 5.04. Found: C, 69.37; H, 5.08. 6: [h]D
+
1
124.7° (c 0.8, CHCl3); H NMR (CDCl3): l 8.13–7.09
(m, 30 H, PhH), 6.87 (d, 2 H, J 9.0 Hz, CH3OC6H4Oꢀ),
6.69 (d, 2 H, J 9.0 Hz, CH3OC6H4Oꢀ), 5.92 (dd, 1 H,
J1,2 8.0 Hz, J2,3 10.3 Hz, H-2I), 5.81 (d, 1 H, J3,4 3.0 Hz,
H-4II), 5.74 (d, 1 H, J1,2 3.6 Hz, H-1II), 5.52 (m, 1 H,
CH2ꢁCHꢀCH2O), 5.46 (dd, 1 H, J2,3 10.4 Hz, H-2II),
p-Methoxyphenyl 2,4,6-tri-O-benzoyl-i-D-galactopy-
ranoside (4).—To a solution of 2 (6.38 g, 10.0 mmol) in
anhyd CH3OH (150 mL) was added PdCl2 (0.6 g), and
the mixture was stirred at 40 °C for 4 h, at the end of
which time TLC (2:1 petroleum ether–EtOAc) indi-
cated that the reaction was complete. The mixture was
filtered, and the filtrate was concentrated. The residue
was passed through a silica gel column with 2:1
petroleum ether–EtOAc as the eluent to give 4 as a
solid (4.78 g, 80%): [h]D +19.4° (c 1.0, CHCl3); 1H
NMR (CDCl3): l 8.20–7.43 (m, 15 H, PhH), 6.97 (d, 2
H, J 9.1 Hz, CH3OC6H4Oꢀ), 6.67 (d, 2 H, J 9.1 Hz,
CH3OC6H4Oꢀ), 5.80 (d, 1 H, J3,4 3.5 Hz, H-4), 5.61
(dd, 1 H, J1,2 8.0 Hz, J2,3 10.0 Hz, H-2), 5.14 (d, 1 H,
H-1), 4.61–4.52 (m, 2 H, H-6, H-6%), 4.28 (m, 1 H,
H-5), 4.21 (dd, 1 H, H-3). Anal. Calcd for C34H30O10:
C, 68.23; H, 5.02. Found: C, 67.92; H, 5.04.
5.21 (dd,
1
H, H-4I), 4.93–4.86 (m,
2
H,
CH2ꢁCHꢀCH2O), 4.71 (d, 1 H, H-1), 4.49 (dd, 1 H, J5,6
7.6 Hz, J6,6% 11.4 Hz, H-6), 4.43–4.28 (m, 4 H), 4.21
(dd, 1 H, H-3II), 3.84 (m, 1 H, H-5I), 3.81–3.63 (m, 2
H, CH2ꢁCHꢀCH2O), 3.75 (s, 3 H, CH3O), 3.68 (dd, 1
H, J3,4 3.2 Hz, H-3I). 13C NMR (CDCl3): l 165.44,
165.28, 165.28, 165.21, 164.73, 164.50 (PhCO), 155.29,
150.74 (CH3OC6H4Oꢀ), 133.43, 133.36, 132.96, 132.59,
132.21, 129.50, 129.35, 129.21, 129.12, 128.87, 128.68,
128.38, 128.23, 128.09, 127.73, 127.60, 118.50
(CH3OC6H4Oꢀ), 116.88 (CH2ꢁCHꢀCH2O), 113.95
(CH3OC6H4Oꢀ), 100.71, 91.94 (C-1), 72.13, 71.57,
71.29, 70.38, 69.53, 68.71, 67.67, 67.35, 64.58, 62.60,
61.85, 55.19 (CH3O). Anal. Calcd for C64H56O18: C,
69.06; H, 5.04. Found: C, 69.41; H, 5.11.
p-Methoxyphenyl 3-O-allyl-2,4,6-tri-O-benzoyl-i-
galactopyranosyl-(1“3)-2,4,6-tri-O-benzoyl-i- -gal-
actopyranoside (5) and p-methoxyphenyl 3-O-allyl-2,4,6-
tri-O-benzoyl-h- -galactopyranosyl-(1“3)-2,4,6-tri-O-
benzoyl-i- -galactopyranoside (6).—A mixture of 3a,
D-
D
D
3-O-Allyl-2,4,6-tri-O-benzoyl-i-
(1“3)-2,4,6-tri-O-benzoyl-i- -galactopyranosyl
chloroacetimidate (7b) and 3-O-allyl-2,4,6-tri-O-benzoyl
- i - - galactopyranosyl - (1“3) - 2,4,6 - tri - O - benzoyl-
h- -galactopyranosyl trichloroacetimidate (7a).—To a
D
-galactopyranosyl-
D
D
tri-
3b (1.35 g, 2.0 mmol) and 4 (1.20 g, 2.0 mmol) were
dried together under high vacuum for 2 h, then dis-
solved in anhyd CH2Cl2 (30 mL). TMSOTf (30 mL, 0.08
equiv) was added dropwise at −25 °C with N2 protec-
tion. The reaction mixture was stirred for 3 h, during
which time the mixture was gradually warmed to ambi-
ent temperature. Then the mixture was neutralized with
Et3N, concentrated and purified by column chromatog-
raphy (2:1 petroleum ether–EtOAc) to afford 5 (1.20 g,
54%) and 6 (0.69 g, 31%), respectively, as foamy solids:
D
D
solution of 5 (11.12 g, 10.0 mmol) in 4:1 CH3CN–H2O
(250 mL) was added CAN (43.86 g, 80.0 mmol), and
the mixture was stirred at rt for 30 min, at the end of
which time TLC (2:1 petroleum ether–EtOAc) indi-
cated that the reaction was complete. The mixture was
extracted with EtOAc, and the extract was washed with
water. The organic layer was concentrated and purified
by column chromatography (2:1 petroleum ether–
1
5: [h]D +52.3° (c 1.1, CHCl3); H NMR (CDCl3): l

L. Chen, F. Kong / Carbohydrate Research 337 (2002) 1373–1380
1377
Hz, H-4), 4.66 (d, 1 H, H-1), 4.28 (dd, 1 H, J5,5% 12.2
Hz, H-5), 4.00 (ABq, 2 H, J 14.9 Hz, ClCH2CO), 3.63
(dd, 1 H, H-5%), 3.49 (s, 3 H, CH3O). Anal. Calcd for
C22H21ClO8: C, 58.86; H, 4.68. Found: C, 58.69; H,
4.73.
EtOAc) to afford a solid. To a solution of the solid in
CH2Cl2 (80 mL) were added trichloroacetonitrile (3.0
mL) and anhyd potassium carbonate (10.0 g). The
reaction mixture was stirred overnight at rt and then
filtered, and the filtrate was concentrated in vacuo. The
residue was purified by column chromatography (2:1
petroleum ether–EtOAc) to give 7b (5.52 g, 48%) and
Methyl 2,3-di-O-benzoyl-i- -xylopyranoside (10).—
D
To a solution of 9 (4.49 g, 10.0 mmol) in EtOH (350
mL)–CH2Cl2 (50 mL) was added thiourea (0.94 g, 13.0
mmol), and the mixture was refluxed for 16 h, at the
end of which time TLC (3:1 petroleum ether–EtOAc)
indicated that the reaction was complete. The mixture
was concentrated, and the residue was passed through a
silica gel column with 3:1 petroleum ether–EtOAc as
the eluent to give 10 as foamy solid (2.98 g, 80%); [h]D
7a (2.76 g, 24%), respectively, as syrups: 7b: [h]D
+
1
66.5° (c 1.0, CHCl3); H NMR (CDCl3): l 8.56 (s, 1 H,
NH), 8.18–7.10 (m, 30 H, PhH), 6.05 (d, 1 H, J3,4 3.3
Hz, H-4II), 5.96 (d, 1 H, J1,2 8.3 Hz, H-1I), 5.86 (dd, 1
H, J2,3 9.8 Hz, H-2I), 5.72 (d, 1 H, J3,4 3.3 Hz, H-4I),
5.49 (m, 1 H, CH2ꢁCHꢀCH2O), 5.27 (dd, 1 H, J1,2 7.8
Hz, J2,3 10.1 Hz, H-2II), 5.03–4.88 (m,
2 H,
1
CH2ꢁCHꢀCH2O), 4.89 (d, 1 H, H-1II), 4.62 (dd, 1 H,
J5,6 6.8 Hz, J6,6% 11.5 Hz, H-6), 4.51 (m, 2 H), 4.35–4.28
(m, 2 H), 4.23 (m, 1 H, H-5II), 4.08 (m, 1 H, H-5I),
4.02–3.78 (m, 2 H, CH2ꢁCHꢀCH2O), 3.66 (dd, 1 H,
H-3II). Anal. Calcd for C59H50Cl3NO17: C, 61.54; H,
4.35. Found: C, 61.31; H, 4.39. 7a: [h]D +61.7° (c 1.0,
CHCl3); 1H NMR (CDCl3): l 8.47 (s, 1 H, NH),
8.15–7.06 (m, 30 H, PhH), 6.70 (d, 1 H, J1,2 3.6 Hz,
H-1I), 6.14 (d, 1 H, J3,4 3.3 Hz, H-4II), 5.76–5.73 (m, 2
H, H-4I, H-2I), 5.50 (m, 1 H, CH2ꢁCHꢀCH2O), 5.29
(dd, 1 H, J1,2 7.9 Hz, J2,3 10.0 Hz, H-2II), 5.03–4.91 (m,
2 H, CH2ꢁCHꢀCH2O), 5.02 (d, 1 H, H-1II), 4.65 (dd, 1
H, H-6), 4.59 (m, 1 H, H-5II), 4.55–4.35 (m, 4 H), 4.19
(m, 1 H, H-5I), 4.06–3.81 (m, 2 H, CH2ꢁCHꢀCH2O),
3.72 (dd, 1 H, H-3II). Anal. Calcd for C59H50Cl3NO17:
C, 61.54; H, 4.35. Found: C, 61.29; H, 4.41.
+54.4° (c 1.0, CHCl3); H NMR (CDCl3): l 8.00–7.37
(m, 10 H, PhH), 5.38–5.28 (m, 2 H, H-3, H-2), 4.61 (d,
1 H, J1,2 6.3 Hz, H-1), 4.21 (dd, 1 H, J4,5 4.8 Hz, J5,5%
11.9 Hz, H-5), 4.01 (m, 1 H, H-4), 3.53 (dd, 1 H, J4,5%
8.4 Hz, H-5%), 3.51 (s, 3 H, CH3O), 2.80 (br, 1 H, OH).
Anal. Calcd for C20H20O7: C, 64.52; H, 5.38. Found: C,
64.33; H, 5.40.
Methyl 3-O-allyl-2,4,6-tri-O-benzoyl-i-
ranosyl-(1“3)-2,4,6-tri-O-benzoyl-i- -galactopyran-
osyl-(1“4)-2,3-di-O-benzoyl-i- -xylopyranoside (11)
and methyl 3-O-allyl-2,4,6-tri-O-benzoyl-i- -galacto-
pyranosyl-(1“3)-2,4,6-tri-O-benzoyl-h- -galactopy-
ranosyl-(1“4)-2,3-di-O-benzoyl-i- -xylopyranoside
D-galactopy-
D
D
D
D
D
(12).—A mixture of 7a, 7b (1.15 g, 1.0 mmol) and 10
(0.37 g, 1.0 mmol) were dried together under high
vacuum for 2 h, then dissolved in anhyd CH2Cl2 (20
mL). TMSOTf (30 mL, 0.16 equiv) was added dropwise
at −25 °C with N2 protection. The reaction mixture
was stirred for 3 h, during which time the mixture was
gradually warmed to ambient temperature. Then the
mixture was neutralized with Et3N and concentrated,
and the crude product was purified by flash chromato-
graphy (2:1 petroleum ether–EtOAc) to afford 11 (0.54
g, 40%), and 12 (0.54 g, 40%), respectively, as foamy
solids: 11: [h]D +24.1° (c 1.2, CHCl3); 1H NMR
(CDCl3): l 8.05–7.12 (m, 40 H, PhH), 5.82 (d, 1 H, J3,4
3.4 Hz, H-4III), 5.68 (d, 1 H, J3,4 3.3 Hz, H-4II), 5.55
(dd, 1 H, J2,3=J3,4=7.5 Hz, H-3I), 5.49 (m, 1 H,
CH2ꢁCHꢀCH2O), 5.48 (dd, 1 H, J1,2 7.9 Hz, J2,3 10.0
Hz, H-2III), 5.22 (dd, 1 H, J1,2 7.9 Hz, J2,3 10.1 Hz,
H-2II), 5.18 (dd, 1 H, J1,2 6.1 Hz, H-2I), 5.01–4.87 (m,
2 H, CH2ꢁCHꢀCH2O), 4.80 (d, 1 H, H-1III), 4.71 (d, 1
H, H-1II), 4.56 (dd, 1 H), 4.45 (d, 1 H, H-1I), 4.28 (dd,
1 H), 4.16–4.09 (m, 2 H), 4.01 (m, 1 H, H-5), 4.00–3.75
(m, 2 H, CH2ꢁCHꢀCH2O), 3.94–3.84 (m, 3 H), 3.67
(dd, 1 H), 3.62 (dd, 1 H, H-3III) 3.38 (s, 3 H, CH3O),
3.25 (m, 1 H, H-4I). 13C NMR (CDCl3): l 165.66,
165.49, 165.23, 165.19, 164.94, 164.85, 163.98, 163.76
(PhCO), 133.49, 132.87, 132.71, 132.64, 132.60, 132.55,
132.51, 132.40, 131.97, 129.71, 129.57, 129.49, 129.42,
129.40, 129.31, 129.27, 129.21, 129.18, 129.09, 129.06,
Methyl
xylopyranoside (9).—To a solution of methyl 2,3,4-tri-
O-acetyl-b- -xylopyranoside (8, 5.80 g, 20.0 mmol) in
2,3-di-O-benzoyl-4-O-chloroacetyl-i-D-
D
MeOH (80 mL) was added 4.0 M NaOMe–MeOH
solution dropwise to pH 10. After stirring the mixture
at rt for 5 h, TLC (EtOAc) indicated that the reaction
was complete. The reaction mixture was directly passed
through a silica gel column with 3:1 EtOH–MeOH as
the eluent to give a solid. The solid was dispersed in
benzene (150 mL), and Bu2SnO (5.23 g, 21.0 mmol) was
added. The mixture was heated under reflux for 2 h,
then cooled to rt, at which time ClCH2COCl (1.59 mL,
20.0 mol) was added to the mixture. The reaction was
carried out at rt for 1 h. To the solution were added
pyridine (8 mL), BzCl (4.87 mL, 42.0 mmol), and the
mixture was stirred overnight at rt. TLC (3:1 petroleum
ether–EtOAc) indicated that the reaction was complete.
The mixture was diluted with CH2Cl2, washed with 1 N
HCl, water, and satd aq NaHCO3. The organic layer
was combined, dried, and concentrated. Purification by
column chromatography (3:1 petroleum ether–EtOAc)
gave 9 (6.46 g, 72%) as a syrup: [h]D +63.0° (c 1.0,
CHCl3); 1H NMR (CDCl3): l 7.99–7.36 (m, 10 H,
PhH), 5.59 (dd, 1 H, J2,3=J3,4=7.8 Hz, H-3), 5.32 (dd,
1 H, J1,2 5.8 Hz, H-2), 5.21 (m, 1 H, J4,5 4.6 Hz, J4,5% 7.5

1378
L. Chen, F. Kong / Carbohydrate Research 337 (2002) 1373–1380
129.06, 129.03, 128.97, 128.89, 128.83, 128.79, 128.11,
128.07, 128.01, 127.98, 127.91, 127.83, 127.78, 127.74,
127.70, 127.64, 127.52, 117.08 (CH2ꢁCHꢀCH2O),
101.17, 101.06, 100.83 (C-1III, II, I), 77.07, 75.79, 75.24,
71.53, 71.16, 70.80, 70.74, 70.06, 69.73, 66.08, 62.08,
61.81, 61.72, 56.20 (CH3O). Anal. Calcd for C77H68O23:
C, 67.94; H, 5.00. Found: C, 67.87; H, 5.07. 12: [h]D
128.12, 127.99, 101.48, 101.18, 100.78 (C-1), 76.74,
75.69, 73.49, 71.80, 71.61, 71.59, 71.24, 71.11, 70.42,
70.03, 69.87, 62.27, 62.06, 61.95, 56.56 (CH3O). Anal.
Calcd for C74H64O23: C, 67.27; H, 4.85. Found: C,
66.99; H, 4.82.
p-Methoxyphenyl 2,4,6-tri-O-benzoyl-i-D-galactopy-
ranosyl-(1“3)-2,4,6-tri-O-benzoyl-i- -galactopyran-
D
1
+74.0° (c 1.0, CHCl3); H NMR (CDCl3): l 8.09–6.99
oside (15).—To a solution of 5 (2.22 g, 2.0 mmol) in
anhyd CH3OH (50 mL) was added PdCl2 (0.1 g), and
the mixture was stirred at 40 °C for 4 h, at the end of
which time TLC (2:1 petroleum ether–EtOAc) indi-
cated that the reaction was complete. The mixture was
filtered, and the filtrate was concentrated. The residue
was passed through a silica gel column with 2:1
petroleum ether–EtOAc as the eluent to give 15 as a
(m, 40 H, PhH), 5.98 (d, 1 H, J3,4=3.3 Hz, H-4III), 5.74
(d, 1 H, J3,4=3.2 Hz, H-4II), 5.53 (dd, 1 H, J2,3
=
H,
J
3,4=8.9 Hz, H-3I), 5.51–5.39 (m,
1
CH2ꢁCHꢀCH2O), 5.42–5.40 (m, 2 H), 5.19 (dd, 1 H,
J1,2 7.8 Hz, J2,3 10.0 Hz, H-2III), 5.12 (dd, 1 H, J1,2 7.2
Hz, J2,3 9.2 Hz, H-2I), 5.01–4.87 (m,
2
H,
CH2ꢁCHꢀCH2O), 4.86 (d, 1 H, H-1III), 4.74 (dd, 1 H),
4.54–4.41 (m, 4 H), 4.33 (dd, 1 H), 4.27 (dd, 1 H),
1
syrup (1.93 g, 90%): [h]D +72.9° (c 1.0, CHCl3); H
4.16–4.01 (m,
3
H), 4.01–3.76 (m,
2
H,
NMR (CDCl3): l 8.07–7.15 (m, 30 H, PhH), 6.82 (d, 2
H, J 9.1 Hz, CH3OC6H4Oꢀ), 6.55 (d, 2 H, J 9.1 Hz,
CH3OC6H4Oꢀ), 5.98 (d, 1 H, J3,4 3.3 Hz, H-4II), 5.85
(dd, 1 H, J1,2 7.9 Hz, J2,3 9.8 Hz, H-2II), 5.65 (d, 1 H,
J3,4 3.3 Hz, H-4I), 5.16 (dd, 1 H, J1,2 7.7 Hz, J2,3 9.8 Hz,
H-2I), 4.95 (d, 1 H, H-1II), 4.92 (d, 1 H, H-1I), 4.65–
4.56 (m, 2 H), 4.47 (dd, 1 H), 4.34–4.30(m, 2 H),
4.16–4.07 (m, 2 H), 3.92 (m, 1 H), 3.67 (s, 3 H, CH3O);
Anal. Calcd for C61H52O18: C, 68.28; H, 4.85. Found:
C, 68.50; H, 4.89.
CH2ꢁCHꢀCH2O), 3.61 (dd, 1 H, J2,3 10.0 Hz, H-3III),
3.42 (dd, 1 H), 3.38 (s, 3 H, CH3O); 13C NMR (CDCl3):
l 165.74, 165.67, 165.44, 165.27, 164.72, 164.72,
1645.63, 163.92 (PhCO), 133.49, 132.76, 132.63, 132.37,
132.32, 131.87, 129.73, 129.64, 129.57, 129.44, 129.32,
129.21, 128.99, 128.96, 128.92, 128.80, 128.73, 128.20,
128.12, 128.04, 127.94, 127.89, 127.86, 127.82, 127.60,
127.47, 117.05 (CH2ꢁCHꢀCH2O), 101.41, 101.13, 97.60
(C-1), 75.93, 74.78, 72.70, 72.39, 71.38, 70.98, 70.85,
70.74, 70.09, 69.59, 67.89, 66.17, 63.59, 63.41, 61.92,
56.10 (CH3O). Anal. Calcd for C77H68O23: C, 67.94; H,
5.00. Found: C, 67.78; H, 5.02.
p-Methoxyphenyl (methyl 2,3,4-tri-O-acetyl-i-
glucopyranosyluronate)-(1“3)-2,4,6-tri-O-benzoyl-i-
-galactopyranosyl-(1“3)-2,4,6-tri-O-benzoyl-i-D-
D-
D
Methyl
(1“3)-2,4,6-tri-O-benzoyl-i-
4)-2,3-di-O-benzoyl-i- -xylopyranoside (13).—To
2,4,6-tri-O-benzoyl-i-
D-galactopyranosyl-
galactopyranoside (16).—A mixture of 14 (0.96 g, 2.0
mmol) and 15 (2.14 g, 2.0 mmol) were dried together
under high vacuum for 2 h, then dissolved in anhyd
CH2Cl2 (40 mL). TMSOTf (60 mL, 0.16 equiv) was
added dropwise at −25 °C with N2 protection. The
reaction mixture was stirred for 3 h, during which time
the mixture was gradually warmed to ambient tempera-
ture. Then the mixture was neutralized with Et3N,
concentrated and purified by column chromatography
(1:1 petroleum ether–EtOAc) to afford 16 (1.53 g, 55%)
D
-galactopyranosyl-(1“
D
a
solution of 11 (1.36 g, 1.0 mmol) in anhyd CH3OH (50
mL) was added PdCl2 (0.1 g), and the mixture was
stirred at 40 °C for 4 h, at the end of which time TLC
(1:1 petroleum ether–EtOAc) indicated that the reac-
tion was complete. The mixture was filtered, and the
filtrate was concentrated. The residue was passed
through a silica gel column with 1.5:1 petroleum ether–
EtOAc as the eluent to give 13 as a syrup (1.19 g, 90%):
1
1
as foamy solid: [h]D +43.6° (c 0.8, CHCl3); H NMR
[h]D +9.1° (c 1.3, CHCl3); H NMR (CDCl3): l 8.04–
7.13 (m, 40 H, PhH), 5.81 (d, 1 H, J3,4 3.5 Hz, H-4III),
(CDCl3): l 8.11–7.15 (m, 30 H, PhH), 6.77 (d, 2 H, J
9.1 Hz, CH3OC6H4O), 6.52 (d, 2 H, J 9.1 Hz,
CH3OC6H4O), 5.92 (d, 1 H, J3,4 3.6 Hz, H-4II), 5.78
(dd, 1 H, J1,2 7.9 Hz, J2,3 9.7 Hz, H-2II), 5.72 (d, 1 H,
J3,4 3.4 Hz, H-4I), 5.41 (dd, 1 H, J1,2 7.8 Hz, J2,3 9.9 Hz,
H-2I), 5.07 (dd, 1 H, J3,4=J4,5=9.5 Hz, H-4III), 4.88
(d, 1 H, H-1II), 4.84 (d, 1 H, H-1I), 4.82 (dd, 1 H,
H-3III), 4.65 (dd, 1 H, J1,2 7.5 Hz, J2,3 9.5 Hz, H-2III),
4.58–4.35 (m, 4 H), 4.50 (d, 1 H, H-1III), 4.24 (dd, 1 H,
H-3II), 4.10–4.03 (m, 3 H), 3.80 (d, 1 H, H-5III), 3.65 (s,
3 H, CH3O), 3.63 (s, 3 H, CH3O), 1.91 (s, 3 H,
CH3CO), 1.80 (s, 3 H, CH3CO), 1.34 (s, 3 H, CH3CO);
5.62 (d, 1 H, J3,4 3.2 Hz, H-4II), 5.57 (dd, 1 H, J2,3
J
=
3,4=7.5 Hz, H-3I), 5.51 (dd, 1 H, J1,2 7.6 Hz, J2,3 10.0
Hz, H-2III), 5.19 (dd, 1 H, J1,2 6.1 Hz, J2,3 7.8 Hz, H-2I),
5.10 (dd, 1 H, J1,2 7.7 Hz, J2,3 10.0 Hz, H-2II), 4.83 (d,
1 H, H-1III), 4.69 (d, 1 H, H-1II), 4.55 (dd, 1 H, H-3II),
4.47 (d, 1 H, H-1I), 4.28 (dd, 1 H), 4.21 (dd, 1 H,
H-3III), 4.07 (dd, 1 H, J5,6 4.7 Hz, J6,6% 11.8 Hz, H-6),
4.02 (m, 1 H, H-5III), 3.94–3.85 (m, 4 H), 3.70 (dd, 1 H,
J4,5 7.5 Hz, J5,5% 11.5 Hz, H-5I), 3.39 (s, 3 H, CH3O),
3.27 (m, 1 H, H-4I); 13C NMR (CDCl3): l 166.27,
166.01, 165.89, 165.80, 165.43, 165.29, 165.19, 164.26
(PhCO), 133.36, 133.23, 133.02, 132.94, 132.91, 132.89,
132.86, 130.00, 129.93, 129.82, 129.63, 129.53, 129.46,
129.28, 129.21, 128.80, 128.77, 128.47, 128.43, 128.38,
13C NMR (CDCl3):
l
169.43, 168.48, 168.09
(3CH3CO), 166.28 (ꢀCO2CH3), 165.63, 165.51, 165.32,
164.93, 164.03, 163.56 (PhCO), 155.09, 150.81

L. Chen, F. Kong / Carbohydrate Research 337 (2002) 1373–1380
1379
(CH3OC6H4Oꢀ), 132.71, 132.63, 132.58, 132.53, 132.51,
132.35, 129.70, 129.65, 129.41, 129.38, 129.18, 129.07,
128.96, 128.93, 128.78, 128.05, 127.91, 127.87, 127.77,
purified by column chromatography (1:1 petroleum
ether–EtOAc) to afford 18 (0.25 g, 31%), and 19 (0.25
g, 31%), respectively, as foamy solids. Alternatively,
donor 17 (0.71 g, 0.5 mmol) and acceptor 10 (0.19 g,
0.5 mmol) were dried together under high vacuum for 2
h, then dissolved in anhyd CH2Cl2 (20 mL). TMSOTf
(30 mL, 0.31 equiv) was added dropwise at −25 °C
with N2 protection. The reaction mixture was stirred
for 3 h, during which time the mixture was gradually
warmed to ambient temperature. Then the mixture was
neutralized with triethylamine, concentrated and
purified by column chromatography (1:1 petroleum
ether–EtOAc) to afford 18 (0.33 g, 40%) as foamy
solid: 18: [h]D +23.7° (c 1.0, CHCl3); 1H NMR
(CDCl3): l 8.05–7.11 (m, 40 H, PhH), 5.76 (d, 1 H, J3,4
3.5 Hz, H-4III), 5.69 (d, 1 H, J3,4 3.4 Hz, H-4II), 5.53
(dd, 1 H, J2,3=J3,4=7.7 Hz, H-3I), 5.45 (dd, 1 H, J1,2
8.2 Hz, H-2III), 5.35 (dd, 1 H, J1,2 7.5 Hz, H-2II), 5.16
118.29, 113.86 (CH3OC6H4Oꢀ), 100.85, 100.62, 100.19
II,
(C-1III,
I), 72.10, 71.77, 71.48, 71.42, 71.15, 70.97,
70.31, 69.65, 69.05, 68.60, 62.65, 61.99, 55.05, 52.23 (2
CH3O), 19.86, 19.86, 19.06 (3 CH3CO). Anal. Calcd for
C74H68O27: C, 63.98; H, 4.90. Found: C, 63.79; H, 4.95.
(Methyl 2,3,4-tri-O-acetyl-i-
ate)-(1“3)-2,4,6-tri-O-benzoyl-i-
(1“3)-2,4,6-tri-O-benzoyl-h- -galactopyranosyl
chloroacetimidate (17a) and (methyl 2,3,4-tri-O-acetyl-i
-glucopyranosyluronate)-(1“3)-2,4,6-tri-O-benzoyl-
-galactopyranosyl-(1“3)-2,4,6-tri-O-benzoyl-i-D-
D
-glucopyranosyluron-
-galactopyranosyl-
tri-
D
D
-
D
i-
D
galactopyranosyl trichloroacetimidate (17b).—To a so-
lution of 16 (1.39 g, 1.0 mmol) in 4:1 CH3CN–H2O (50
mL) was added CAN (4.39 g, 8.0 mmol), and the
mixture was stirred at rt for 30 min, at the end of which
time TLC (1:1 petroleum ether–EtOAc) indicated that
the reaction was complete. The mixture was extracted
with EtOAc, and the extract was washed with water.
The organic layer was concentrated under reduced pres-
sure, and the crude product was purified by column
chromatography (1:1 petroleum ether–EtOAc) to af-
ford a solid. To a solution of the solid in CH2Cl2 (20
mL) were added trichloroacetonitrile (0.5 mL) and an-
hyd potassium carbonate (1.0 g). The reaction mixture
was stirred overnight at rt and then filtered, and the
filtrate was concentrated in vacuo. The residue was
purified by column chromatography (1:1 petroleum
ether–EtOAc) to give 17a (0.29 g, 20%) and 17b (0.71
g, 50%), respectively, as syrups: 17a: [h]D +65.4° (c 1.0,
CHCl3); 1H NMR (CDCl3): l 8.44 (s, 1 H, NH),
8.11–7.07 (m, 30 H, PhH), 6.66 (d, 1 H, J1,2 3.8 Hz,
H-1I); Anal. Calcd for C69H62Cl3NO26: C, 58.04; H,
4.35. Found: C, 57.83; H, 4.36. 17b: [h]D +49.3° (c 1.0,
CHCl3); 1H NMR (CDCl3): l 8.54 (s, 1 H, NH),
8.08–7.15 (m, 30 H, PhH), 5.89 (d, 1 H, J1,2 8.3 Hz,
H-1I); Anal. Calcd for C69H62Cl3NO26: C, 58.04; H,
4.35. Found: C, 57.78; H, 4.39.
(dd, 1 H, J1,2 6.1 Hz, H-2I), 5.06 (dd, 1 H, J2,3=J3,4
=
9.4 Hz, H-3IV), 4.81 (dd, 1 H, J3,4=J4,5=9.4 Hz,
H-4IV), 4.75 (d, 1 H, J1,2 7.8 Hz, H-1IV), 4.63 (dd, 1 H,
H-2IV), 4.62 (d, 1 H, H-1III), 4.48 (d, 1 H, H-1II), 4.44
(d, 1 H, H-1I), 4.44 (m, 1 H), 4.34 (m, 1 H), 4.14–3.98
(m, 4 H), 3.88–3.79 (m, 3 H), 3.79 (d, 1 H, H-5IV), 3.65
(dd, 1 H), 3.62 (s, 3 H, CH3O), 3.38 (s, 3 H, CH3O),
3.21 (m, 1 H), 1.91 (s, 3 H, CH3CO), 1.80 (s, 3 H,
CH3CO), 1.32 (s, 3 H, CH3CO); 13C NMR (CDCl3): l
169.89, 168.93, 168.51, 166.64, 165.97, 165.79, 165.36,
165.25, 165.25, 165.17, 164.05, 163.85 (ꢀCOꢀ), 133.15,
132.98, 132.90, 132.72, 129.99, 129.81, 129.67, 129.59,
129.53, 129.25, 129.14, 128.74, 128.70, 128.42, 128.29,
128.25, 128.12, 127.97, 101.41, 101.16, 101.09, 100.51
(C-1), 75.60, 72.34, 71.82, 71.74, 71.69, 71.59, 71.33,
71.08, 70.54, 70.37, 69.91, 69.29, 68.84, 68.05, 62.27,
62.21, 62.02, 56.54, 52.65 (CH3O), 20.30, 20.30, 19.42
(CH3CO). Anal. Calcd for C87H80O32: C, 63.81; H,
4.89. Found: C, 63.52; H, 4.91. 19: [h]D +22.8° (c 1.0,
CHCl3); 1H NMR (CDCl3): l 8.02–7.11 (m, 40 H,
PhH), 5.79 (d, 1 H, J3,4 3.5 Hz, H-4III), 5.71 (dd, 1 H,
J3,4 3.4 Hz, H-4II), 5.54 (dd, 1 H, J2,3=J3,4=7.6 Hz,
H-3I), 5.48–5.43 (m, 3 H), 5.39 (dd, 1 H, J1,2 8.0 Hz,
H-2II), 5.26 (s, 1 H, H-4IV), 5.17 (dd, 1 H, J1,2 6.1 Hz,
J2,3 7.9 Hz, H-2I), 4.81 (d, 1 H, J1,2 7.8 Hz, H-1III), 4.68
(d, 1 H, H-1II), 4.55 (dd, 1 H), 4.44 (d, 1 H, H-1I),
4.21–4.16 (m, 3 H), 4.11–4.05 (dd, 1 H), 4.09 (m, 1 H,
H-5), 3.94–3.73 (m, 5 H), 3.66 (dd, 1 H), 3.62 (s, 3 H,
CH3O), 3.38 (s, 3 H, CH3O), 3.23 (dd, 1 H), 1.74 (s, 3
H, CH3CO), 1.61 (s, 6 H, CH3CO); 13C NMR (CDCl3):
l 169.44, 168.24, 168.18, 165.80, 165.80, 165.80, 165.47,
165.47, 165.27, 165.17, 164.10, 163.95 (ꢀCOꢀ), 133.32,
133.24, 133.00, 132.94, 132.86, 132.32, 130.01, 129.95,
129.81, 129.65, 129.62, 129.53, 129.47, 129.31, 129.26,
129.15, 129.02, 128.77, 128.70, 128.48, 128.42, 128.31,
128.11, 127.98, 127.78, 101.40, 101.40, 101.17, 89.66
(C-1), 75.60, 73.12, 71.77, 71.52, 71.12, 71.01, 70.40,
70.03, 69.92, 67.39, 65.23, 65.06, 62.30, 62.05, 61.64,
Methyl (methyl 2,3,4-tri-O-acetyl-i-
osyluronate)-(1“3)-2,4,6-tri-O-benzoyl-i-
pyranosyl-(1“3)-2,4,6-tri-O-benzoyl-i- -galactopy-
ranosyl-(1“4)-2,3-di-O-benzoyl-i- -xylopyranoside
(18) and methyl (methyl 2,3,4-tri-O-acetyl-h- -glucopy-
ranosyluronate)-(1“3)-2,4,6-tri-O-benzoyl-i- -gal-
actopyranosyl-(1“3)-2,4,6-tri-O-benzoyl-i- -galacto-
pyranosyl-(1“4)-2,3-di-O-benzoyl-i- -xylopyranoside
D
-glucopyran-
D
-galacto-
D
D
D
D
D
D
(19).—A mixture of 14 (0.24 g, 0.5 mmol) and 13 (0.66
g, 0.5 mmol) were dried together under high vacuum
for 2 h, then dissolved in anhyd CH2Cl2 (20 mL).
TMSOTf (30 mL, 0.31 equiv) was added dropwise at
−25 °C with N2 protection. The reaction mixture was
stirred for 3 h, during which time the mixture was
gradually warmed to ambient temperature. Then the
mixture was neutralized with Et3N, concentrated and

1380
L. Chen, F. Kong / Carbohydrate Research 337 (2002) 1373–1380
56.54, 52.27 (CH3O), 20.46, 20.46, 20.28 (CH3CO).
Anal. Calcd for C87H80O32: C, 63.81; H, 4.89. Found:
C, 63.70; H, 4.92.
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Acknowledgements
50, 21–125.
This work was supported by The Chinese Academy
of Sciences (KIP-RCEES9904), The National Natural
Science Foundation of China (Projects 39970864 and
30070815), and The Ministry of Science and Technol-
ogy.
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