A facile and effective synthesis of α-(1→6)-linked mannose di-, tri-, tetra-, hexa-, octa-, and dodecasaccharides, and β-(1→6)-linked glucose di-, tri-, tetra-, hexa-, and octasaccharides using sugar trichloroacetimidates as the donors and unprotected or partially protected glycosides as the acceptors

www.elsevier.nl/locate/carres

Carbohydrate Research 332 (2001) 1–21

A facile and effective synthesis of a-(16)-linked

mannose di-, tri-, tetra-, hexa-, octa-, and

dodecasaccharides, and b-(16)-linked glucose di-, tri-,

tetra-, hexa-, and octasaccharides using sugar

trichloroacetimidates as the donors and unprotected or

partially protected glycosides as the acceptors

Yuliang Zhu, Fanzuo Kong*

Research Center for Eco-En6ironmental Sciences, Chinese Academy of Sciences, Academia Sinica, PO Box 2871,

Beijing 100085, People’s Republic of China

Received 15 December 2000; accepted 28 February 2001

Abstract

Reaction of 2,3,4,6-tetra-O-acetyl-a-

presence of TMSOTf selectively gave allyl 2,3,4,6-tetra-O-acetyl-a-

through an orthoester intermediate. Benzoylation of 3, followed by deallylation, and then trichloroimidation afforded

the disaccharide donor 2,3,4,6-tetra-O-acetyl-a- -mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-a- -mannopyranosyl

trichloroimidate, while benzoylation of 3 followed by selective removal of acetyl groups yielded the disaccharide

-mannopyranoside. Coupling of 5 with 6 gave the

D

-mannopyranosyl trichloroimidate with allyl a-

D

-mannopyranoside in the

D

-mannopyranosyl-(16)-a-

D

-mannopyranoside

D

acceptor allyl a-

tetrasaccharide allyl 2,3,4,6-tetra-O-acetyl-a-

(16)-a- -mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-a-

saccharide donor 2,3,4,6-tetra-O-acetyl-a- -mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-a-

(16)-2,3,4-tri-O-benzoyl-a- -mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-a- -mannopyranosyl

and the tetrasaccharide acceptor allyl a- -mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-a-

2,3,4-tri-O-benzoyl-a- -mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-a- -mannopyranoside, respectively, by the same

D

-mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-a-

D

-mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-a-

D

-mannopyranosyl-

D

D-mannopyranoside, which were converted into the tetra-

D

-mannopyranosyl-

trichloroimdate

D

-mannopyranosyl-(16)-

D

strategies as used for conversion of 3 into 5 and 6. Condensation of 5 with 13 gave the hexasaccharide 14, while

condensation of 12 with 13 gave the octasaccharide 17. Dodecasaccharide 21 was obtained by the coupling of 12 with

the octasaccharide acceptor 20. Similar strategies were used for the syntheses of b-(16)-linked glucose di-, tri-,

tetra-, hexa-, and octamers. Deprotection of the oligosaccharides in ammonia-saturated methanol yielded the free

Keywords: Oligosaccharides; Trichloroimidates; Regio- and stereoselective synthesis

1. Introduction

Great effort has been contributed to the

development of new strategies for glycosidic

* Corresponding author. Tel.: +86-10-62936613; fax: 86-

10-62923563.

E-mail address: fzkong@mail.rcees.ac.cn (F. Kong).

coupling owing to the growing importance of

PII: S0008-6215(01)00070-2

2

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

synthetic oligosaccharides in glycobiology.¹In

the past decades, there has been considerable

progress²in the methods for construction of

glycosidic linkages. However, compared to the

synthesis of oligopeptides and oligonucle-

otides, the synthesis of oligosaccharides is still

laborious work. The use of unprotected or

partially protected sugars in glycosidic cou-

pling is of particular interest since synthetic

routes can be substantially simpliﬁed³to read-

ily afford biologically important compounds.

Our previous papers have described^3a–da new

method for regio- and stereoselective synthesis

of oligosaccharides via orthoester^4a–iforma-

tion–rearrangement using unprotected or par-

tially protected glycopyranosides as the

glycosyl acceptors and acetylated glycosyl brom-

ides as the donors. This method gave (16)-

linked oligosaccharides in satisfactory yields.

It was found, however, that careful separation

and puriﬁcation of the orthoesters was needed

for the further rearrangement. To simplify the

process we tried the glycosylation in a new

way⁵by which the orthoesters that initially

formed rearranged to the required glycosides

in situ. This one-pot, two-step reaction en-

sured the high regioseletivity of glycosylation

as it comes from the high regioselectivity of

orthoester formation. No separation and

puriﬁcation of the orthoesters was needed,

which simpliﬁed the glycosylation substan-

tially and made the preparation of biologically

important molecules possible in large scale.

Herein we present this one-pot reaction in

detail for the synthesis of a-(16)-linked

mannooligosaccharides and b-(16)-linked

glucooligosaccharides using unprotected or

partially protected glycopyranosides as the

glycosyl acceptors and sugar trichloroacetimi-

dates as the glycosyl donors.

been reported using 2,3,4-tri-O-benzoyl-6-O-

bromoacetyl-a-

-galactopyranosyl chloride⁸

or 6-O-acetyl-2-O-benzoyl-3,4-di-O-benzyl-a-

-galactopyranosyl tosylate⁹as the glycosyl

D

donor and protected galactose derivatives with

only six-free OH as the acceptors. In contrast

to the synthesis of galactooligosaccharides, lit-

tle attention¹⁰has been paid to the synthesis

of a-(16)-linked mannooligosaccharides

and b-(16)-linked glucooligosaccharides.

The glycosyl imidate donors, initially pro-

posed by Sinay¨¹¹and developed a few years

later by Schmidt,¹²are by far one of the most

convenient intermediates in oligosaccharide

synthesis. It was found that orthoesters were

the intermediates in the glycosylation with

imidates as the donors. Conversion of the

orthoesters to the corresponding glycosides

can be achieved by simply extending the gly-

cosylation time.^13aOur experiment using a

partially protected glycoside as the acceptor

and a trichloroacetimidate as the donor also

gave an orthoester as the intermediate, which

was transformed to the corresponding gly-

coside by addition of extra catalyst or exten-

sion of the reaction time.^13bThus we assumed

that glycosyl imidates will be good donors for

the one-pot, two-step glycosylation. A concise

and efﬁcient synthesis of a-(16)-linked man-

nose di-, tri-, tetra-, hexa-, octa-, and dode-

casaccharides and b-(16)-linked glucose di-,

tri-, tetra-, hexa-, and octasaccharides indi-

cated that this is indeed an excellent method

for construction of (16)-linked manno- and

glucooligosaccharides.

Scheme 1 outlines the synthesis of a-(16)-

linked mannosyl tetrasaccharide. Allyl a- -

D

mannopyranoside¹⁴was chosen as the starting

acceptor since its coupling product can be

converted easily to either a new donor 5 or a

new acceptor 6 by simple chemical transfor-

mation. Thus condensation of 2,3,4,6-tetra-O-

acetyl - a -

imidate^2d(1) with allyl a-

(2) in DMF promoted by TMSOTf afforded

allyl 2,3,4,6-tetra-O-acetyl-a- -mannopyran-

D

- mannopyranosyl trichloroacet-

2. Results and discussion

D

-mannopyranoside

a-(16)-Linked mannooligosaccharides oc-

cur in the cell-wall polysaccharides of yeast,⁶

while b-(16)-linked glucooligosaccharides,

known as gentiooligosaccharides, are found in

lichens⁷and can be used as a biﬁdus factor to

promote animal growth. Stepwise synthesis of

b-(16)-linked galactooligosacchrides has

D

osyl-(16)-a- -mannopyranoside (3), and

D

the crude 3 was benzoylated in situ with ben-

zoyl chloride in pyridine to give allyl 2,3,4,6-

tetra-O-acetyl-a-

2,3,4-tri-O-benzoyl-a-

in a satisfactory yield (67% for two steps). It

D

-mannopyranosyl-(16)-

D

-mannopyranoside (4)

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

3

was noted that the reaction temperature at

addition of TMSOTf was maintained below

−40 °C to ensure orthoester formation with

good regioselectivity; then it was gradually

raised to ambient temperature. The (16)

linkage in 4 was unambiguously veriﬁed from

for H-2, -4, and -3 and H-2%, -3%, and -4%, were

moved to a downﬁeld position by either a

benzoate or an acetate group, to give resonance

at l 5.92, 5.91, 5.41, 5.72, 5.33, and 5.27,

respectively. Deallylation of 4 with PdCl₂in

CH₃COOH–CH₃CONa, followed by reaction

with CCl₃CN in the presence of DBU, fur-

1

its H NMR spectrum in which the resonance

,

Scheme 1. Conditions and reagents: (a) TMSOTf, CH₂Cl₂(DMF), 4 A MS, −42 °C to rt, 3 h; (b) BzCl–pyridine (dry); (c) PdCl₂,

CH₃COOH–CH₃CONa, rt, 12 h; (d) CCl₃CN, CH₂Cl₂, DBU, rt, 2 h; (e) CH₃COCl–CH₃OH, rt; (f) MeOH, NH₃, rt, 2–5 days

or MeOH–MeONa rt.

4

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

acetyl-a-

D

-mannopyranosyl-(16)-2,3,4-tri-

-mannopyranosyl trichloroace-

nished the disaccharide donor 2,3,4,6-tetra-O-

O-benzoyl-a-

D

acetyl-a-

D

-mannopyranosyl-(16)-2,3,4-tri-

-mannopyranosyl trichloroacet-

timidate (5) with the tetrasaccharide acceptor

13 furnished hexasaccharide 14 (72%), and

benzoylation of 14 with benzoyl chloride in

pyridine gave 15 in quantitative yield. Depro-

tection of 15 with ammonia-saturated

methanol afforded unmasked hexasaccharide

16. Condensation of the tetrasaccharide donor

12 with the tetrasaccharide acceptor 13 yielded

the octasaccharide 17 (62%), and further ben-

zoylation quantitatively gave the fully pro-

tected octasaccharide 18. Serious overlapping

O-benzoyl-a-

D

imidate (5) in a good yield (90%), while selec-

tive deacetylation of 4 with acetyl chloride in

methanol¹⁵furnished the disaccharide accep-

tor a-

D

-mannopyranosyl-(16)-2,3,4-tri-O-

-mannopyranoside (6) smoothly

benzoyl-a-

D

(93%). As 6 was more soluble in organic sol-

vents than 2, coupling of 1 with 6 was carried

out in dichloromethane instead of DMF. Oth-

erwise the conditions were the same as de-

scribed for the condensation of 1 with 2.

Benzoylation of the product gave the trisac-

1

resonances in the H NMR spectrum of 18

charide 2,3,4,6-tetra-O-acetyl-a-

ranosyl-(16)-2,3,4-tri-O-benzoyl-a-

nopyranosyl-(16)-2,3,4-tri-O-benzoyl-a-

D

-mannopy-

-man-

made the assignment difﬁcult, while the ¹³C

NMR of 18 still showed no signals at the

region \71 ppm that would indicate (16)

linkages. We were gratiﬁed to ﬁnd that neither

the coupling reaction nor the selective

deacetylation presents any difﬁculties when

the donor or acceptor oligosaccharide chain

became longer. Unprotected octasaccharide 19

was readily obtained by deacylation of 18 in

ammonia-saturated methanol. The octasac-

charide acceptor 20 was prepared in a satisfac-

tory yield (82%) by selective deacetylation of

18 under the same conditions as used for the

preparation of tetrasaccharide acceptor 13

from 10. Coupling of the acceptor 20 with the

tetrasaccharide donor 12 gave the dodecasac-

charide 21. Subsequent benzoylation (22)

and then deprotection gave the unmasked do-

decasaccharide 23.

D

-

mannopyranoside (7) in a satisfactory yield

(72% for two steps). It was found that the

orthoester formed at the initial stage (within

30 min) of the coupling reaction could be

benzoylated and isolated to give the orthoester

1

8. The H NMR spectrum of 8 gave a charac-

teristic peak at l 1.60 for the orthoester, and 8

was transformed easily to the corresponding

trisaccharide 7 in the presence of a catalytic

amount of TMSOTf. Similarly, condensation

of 5 and 6 furnished the tetrasaccharide 9 in a

good yield (65%). Benzoylation of 9 gave 10 in

1

quantitative yield, and the 2D H NMR spec-

trum of 10 gave a clear indication of (16)

linkages as the 12 signals for H-2, -3, and -4 of

the four mannose residues were found at l

13

6.19–5.20. The C NMR spectrum of 10 also

b-(16)-Linked glucose di-, tri-, tetra-,

hexa- and octasaccharides were also success-

fully synthesized using the same strategy as

described above. Orthoester 26, obtained as

the intermediate in the preparation of disac-

charide 27, was also isolated and character-

ized. Scheme 3 shows the syntheses of glucose

oligosaccharides with the yields for each step.

It is noteworthy that almost all of the

oligosacchairides described above were ob-

tained as crystals or solids.

In summary, here we present a very effec-

tive method for the synthesis of a-(16)-

linked

b-(16)-linked glucose oligosaccharides using

sugar imidates as the glycosyl donors and

unprotected or partially protected glycosides

as the glycosyl acceptors.

indicated (16) linkages as all of the C-2, -3,

-4, and -5 signals were at B73 ppm. Depro-

tection of tetrasaccharide 10 in methanol satu-

rated with ammonia gave allyl a-

pyranosyl-(16)-a- -mannopyranosyl-(16)-

a - - mannopyranosyl - (16) - a - - manno-

D

-manno-

D

pyranoside (11). Tetrasaccharide 10 was trans-

formed readily to the tetrasaccharide donor 12

by deallylation with palladium chloride in

CH₃COOH–CH₃COONa, followed by reac-

tion with trichloroacetonitrile (86% for two

steps). Meanwhile the tetrasaccharide acceptor

13 was smoothly prepared (89%) by selective

deacetylation of 10 with acetyl chloride–

methanol.

mannose

oligosaccharides

and

Scheme 2 shows the synthesis of higher

oligosaccharides. Coupling of 2,3,4,6-tetra-O-

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

5

,

Scheme 2. Conditions and reagents: (a) TMSOTf, CH₂Cl₂(DMF), 4 A MS, −42 °C to rt, 3 h; (b) BzCl–pyridine (dry); (c) PdCl₂,

CH₃COOH–CH₃CONa, rt, 12 h; (d) CCl₃CN, CH₂Cl₂, DBU, rt, 2 h; (e) CH₃COCl–CH₃OH, rt; (f) MeOH, NH₃, rt, 2–5 days.

6

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

,

Scheme 3. Conditions and reagents: (a) TMSOTf, CH₂Cl₂(DMF), 4 A MS, −42 °C to rt, 3 h; (b) BzCl–pyridine (dry); (c) PdCl₂,

CH₃COOH–CH₃CONa, rt, 12 h; (d) CCl₃CN, CH₂Cl₂, DBU, rt, 2 h; (e) CH₃COCl–CH₃OH, rt; (f) MeOH, NH₃, rt, 2–5 days.

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

7

under reduced pressure to afford the crude

allyl 2,3,4,6-tetra-O-acetyl-a- -mannopyran-

osyl-(16)-a- -mannopyranoside (3). To the

3. Experimental

D

General methods.—Melting points were de-

termined with a Mel-Temp apparatus. Optical

rotations were determined with a Perkin–

Elmer model 241-MC automatic polarimeter

for solutions in a 1-dm, jacketed cell at 20 °C.

¹H NMR spectra were recorded with Varian

XL-400 and Varian XL-200 spectrometers, for

solutions in CDCl₃with tetramethylsilane

(Me₄Si) as the internal standard. Chemical

shifts are expressed in ppm downﬁeld from the

internal Me₄Si absorption. Mass spectra were

measured using MALTI-TOF–MS with CCA

as matrix or recorded with a VG PLAT-

FORM mass spectrometer using the ESI tech-

nique to introduce the sample. Thin-layer

chromatography (TLC) was performed on sil-

ica gel HF, detection being effected by char-

ring with 30% (v/v) H₂SO₄in MeOH or

sometimes by UV detection. Column chro-

matography 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 performed with a

Gilson HPLC consisting of a pump (model

306), stainless steel packed with silica gel

(Spherisorb SiO₂, 10×300 mm or 4.6×250

mm), differential refractometer (132-RI Detec-

tor), UV–Vis detector (model 118), and

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 pres-

sure. Ethyl acetate–petroleum ether were used

for crystallization and recrystallization.

D

solution of crude 3 in Py (20 mL) BzCl (1.4

mL, 12 mmol) was added dropwise, and the

mixture was stirred overnight at rt. TLC (3:1

petroleum ether–EtOAc) indicated that the

reaction was complete. Ice water was added,

and 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 4 (2310 mg, 67% for two

steps) as colorless crystals: mp 152–154 °C;

[h]_D−14.2° (c 1.3, CHCl₃). ¹H NMR

(CDCl₃): l 8.13–7.22 (m, 15 H, BzꢀH), 6.02

(m, 1 H, CH₂ꢁCHꢀCH₂ꢀ), 5.92–5.90 (m, 2 H,

H-2, H-4), 5.72 (dd, 1 H, J_1,21.6, J_2,32.9 Hz,

H-2^I), 5.47–5.40 (m, 2 H, CH₂ꢁCHꢀCH₂, H-

3), 5.33–5.29 (m, 2 H, CH₂ꢁCHꢀCH₂, H-3^I),

5.27 (t, 1 H, J_3,4, J_4,510.0 Hz, H-4^I), 5.13 (d, 1

H, J_1,21.5 Hz, H-1), 4.86 (d, 1 H, H-1^I),

4.36–4.33 (m, 2 H), 4.20–4.10 (m, 2 H), 4.00–

3.94 (m, 3 H), 3.68–3.65 (dd, 1 H), 2.12 (s, 3

H, CH₃CO), 2.05 (s, 3 H, CH₃CO), 2.00 (s, 3

H, CH₃CO), 1.94 (s, 3 H, CH₃CO). Anal.

Calcd for C₄₄H₄₆O₁₈: C, 61.25; H, 5.34.

Found: C, 61.38; H, 5.29.

2,3,4,6 - Tetra - O - acetyl - h -

osyl-(16)-2,3,4-tri-O-benzoyl-h-

pyranosyl trichloroacetimidate (5).—To a solu-

tion of allyl 2,3,4,6-tetra-O-acetyl-a- -manno-

pyranosyl-(16)-2,3,4-tri-O-benzoyl-a-

D

- mannopyran-

D

-manno-

D

-

mannopyranoside (4) (862 mg, 1 mmol) in

90% AcOH (10 mL) containing AcONa (293

mg, 3 mmol) was added PdCl₂(89 mg, 0.5

mmol), and the mixture was stirred for 12 h,

at the end of which time TLC (2:1 petroleum

ether–EtOAc) indicated that the reaction was

complete. The mixture was diluted with

CH₂Cl₂(30 mL), washed with water and satd

aq NaHCO₃. The organic layer was concen-

trated under reduced pressure, and the residue

thus obtained was passed through a short

silica-gel column with 2:1 petroleum ether–

EtOAc as the eluent to give crude 2,3,4,6-

Allyl 2,3,4,6 - tetra - O - acetyl - h -

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h -

mannopyranoside (4).—2,3,4,6-Tetra-O-acetyl-

a- -mannopyranosyl trichloroacetimidate (1)

(1970 mg, 4 mmol) and allyl a- -mannopyra-

D

- manno-

D

-

D

noside (2) (880 mg, 4 mmol) were dried to-

gether under high vacuum for 2 h, then

dissolved in anhyd DMF (60 mL). TMSOTf

(60 mL, 0.08 equiv) was added dropwise at

−42 °C with N₂protection. The reaction mix-

ture was stirred for 3 h, during which time the

temperature was gradually raised to ambient

temperature. Then the mixture was neutral-

ized with Et₃N, and concentrated to dryness

tetra-O-acetyl-a-

D

-mannopyranosyl-(16)-

-mannopyranose (782

2,3,4-tri-O-benzoyl-

D

mg). The product was dissolved in CH₂Cl₂(20

mL), and then CCl₃CN (0.2 mL, 2 mmol) and

8

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-

h- -mannopyranoside (7).—2,3,4,6-Tetra-O-

acetyl-a- -mannopyranosyl trichloroacetimi-

date (1, 493 mg, 1 mmol) and allyl a-

mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-

a- -mannopyranoside (6, 694 mg, 1 mmol)

DBU (27 mL, 0.18 mmol) were added. The

reaction mixture was stirred for 2 h, at the end

of which time TLC (2:1 petroleum ether–

EtOAc) indicated that the reaction was com-

plete. Concentration of the reaction mixture

followed by puriﬁcation on a silica-gel column

with 2:1 petroleum ether–EtOAc as the eluent

furnished the disaccharide donor 5 as crystals

in a good yield (869.9 mg, 90%): mp 150–

D

-

D

were dried together under high vacuum for 2

h, then dissolved in anhyd CH₂Cl₂(60 mL).

TMSOTf (15 mL, 0.08 equiv) was added drop-

wise at −42 °C with N₂protection. The reac-

tion mixture was stirred for 3 h, during which

time the temperature was gradually raised to

ambient temperature. Then the mixture was

neutralized with Et₃N, and concentrated un-

der reduced pressure to give a syrupy residue.

To the solution of the residue in Py (20 mL),

BzCl (0.35 mL, 3 mmol) was added dropwise,

and the mixture was stirred overnight at rt.

TLC (2:1 petroleum ether–EtOAc) indicated

that the reaction was complete. The mixture

was diluted with CH₂Cl₂, washed sequentially

with 1 N HCl, water, and satd aq NaHCO₃.

The organic layer was combined, dried, and

concentrated. Puriﬁcation by column chro-

matography (2:1 petroleum ether–EtOAc)

gave 7 (962 mg, 72% for two steps) as a

colorless solid: mp 144–147 °C; [h]_D−10.3°

1

153 °C; [h]_D−11.3° (c 1.1, CHCl₃). H NMR

(CDCl₃): l 8.62 (s, 1 H, CꢁNH), 8.14–7.26

(m, 15 H, BzꢀH), 6.59 (d, 1 H, J_1,21.9 Hz,

H-1), 6.16–6.12 (m, 2 H), 5.86 (dd, 1 H, J_2,3

2.8 Hz, H-2), 5.44 (dd, 1 H, J_2,33.4, J_3,410.1

Hz, H-3^I), 5.36 (dd, 1 H, J_1,21.7 Hz, H-2^I),

5.27 (t, 1 H, H-3^I), 4.85 (d, 1 H, H-1^I), 4.59–

4.56 (m, 1 H), 4.15–4.06 (m, 2 H), 3.99–3.95

(m, 1 H), 3.90–3.84 (m, 1 H), 3.73–3.70 (m, 1

H), 2.13 (s, 3 H, CH₃CO), 2.08 (s, 3 H,

CH₃CO), 2.00 (s, 3 H, CH₃CO), 1.91 (s, 3 H,

CH₃CO). Anal. Calcd for C₄₃H₄₂Cl₃NO₁₈: C,

53.39; H, 4.35. Found: C, 53.14; H, 4.42.

Allyl

tri-O-benzoyl-h-

a solution of allyl 2,3,4,6-tetra-O-acetyl-a-

mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-

a- -mannopyranoside (4) (862 mg, 1 mmol) in

h-D

-mannopyranosyl-(16)-2,3,4-

D

-mannopyranoside (6).—To

D

-

D

1

(c 1.5, CHCl₃). H NMR (CDCl₃): l 8.19–

anhyd MeOH (50 mL) was added AcCl (1.5

mL) at 0 °C. The solution was sealed in a ﬂask

and stirred for 10 h at rt, and then another

portion of AcCl (1 mL) was added. The reac-

tion was monitored by TLC (1:2 petroleum

ether–EtOAc) until the starting material dis-

appeared. The solution was neutralized with

Et₃N, then concentrated to dryness. The

residue was passed through a short silica-gel

column to give crystalline 6 (625 mg, 90%),

which was directly used for the next reaction:

mp 159–162 °C; [h]_D−13.8° (c 2.3, CHCl₃).

¹H NMR (CDCl₃): l 8.04–7.21 (m, 15 H,

BzꢀH), 6.00 (m, 1 H, CH₂ꢁCHCH₂ꢀ), 5.95 (t,

1 H, J_3,49.8 Hz, H-4), 5.88 (dd, 1 H, J_2,33.1

Hz, H-3), 5.68 (s, 1 H, H-2), 5.42 (dd, 1 H,

CH₂ꢁCHꢀCH₂), 5.23 (dd, 1 H, CH₂ꢁCHꢀ

CH₂), 5.08 (s, 1 H, H-1), 4.80 (s, 1 H, H-1^I),

4.30–4.28 (m, 2 H), 4.25–4.23 (m, 1 H), 3.92–

3.45 (m, 8 H). Anal. Calcd for C₃₆H₃₈O₁₄: C,

62.25; H, 5.48. Found: C, 62.16; H, 5.53.

7.26 (m, 30 H, Bz-H), 6.18 (t, 1 H, J_3,410.1

Hz, H-4), 6.10–5.95 (m, 3 H, CH₂ꢁCHꢀCH₂,

H-3, H-3^I), 5.94 (t, 1 H, J_3,410.1 Hz, H-4^I),

5.84 (dd, 1 H, J_1,21.5, J_2,33.2 Hz, H-2), 5.77

(dd, 1 H, J_1,21.6, J_2,33.2 Hz, H-2^I), 5.50 (d, 1

H, CH₂ꢁCHꢀCH₂), 5.34–5.31 (m, 2 H,

CH₂ꢁCHꢀCH₂, H-3^II), 5.22–5.18 (m, 2 H, H-

4^II, H-2^II), 5.12 (s, 2 H, H-1, H-1^I), 4.57 (d, 1

H, J_1,21.3 Hz, H-1^II), 4.50–4.39 (m, 2 H,

H-6_B, H-6¹_B), 4.25–4.15 (m, 2 H, H-5, H-5¹),

4.15–4.03 (m, 2 H, H-6_A, H-6¹_A), 3.91–3.87

(m, 2 H, H-6^I_B^I, H-5^II), 3.76–3.73 (m, 2 H,

H-6^I_A^I, CH₂ꢁCHꢀCH₂), 3.31 (d,

1

H,

CH₂ꢁCHꢀCH₂), 2.10 (s, 3 H, CH₃CO), 2.05 (s,

3 H, CH₃CO), 2.00 (s, 3 H, CH₃CO), 1.92 (s,

3 H, CH₃CO). Anal. Calcd for C₇₁H₆₈O₂₆: C,

63.77; H, 5.09. Found: C, 63.63; H, 5.12.

Orthoester 8.—2,3,4,6-Tetra-O-acetyl-a-

mannopyranosyl trichloroacetimidate (1) (493

mg, 1 mmol) and allyl a- -mannopyranosyl-

(16)-2,3,4-tri-O-benzoyl-a- -mannopyran-

oside (6) (694 mg, 1 mmol) were dried to-

D

-

D

Allyl

2,3,4,6-tetra-O-acetyl-h-

D

-manno-

D

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h -

D

-

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

9

(483 mg, 0.5 mmol) and allyl a-

D

-mannopyran-

gether under high vacuum for 2 h, then dis-

solved in anhyd CH₂Cl₂(60 mL). TMSOTf

(7.5 mL, 0.04 equiv) was added dropwise at

−42 °C with N₂protection. The reaction mix-

ture was stirred for 0.5 h. Then the mixture

was neutralized with Et₃N, and concentrated

under reduced pressure. The residue was dis-

solved in Py (20 mL), BzCl (0.35 mL, 3 mmol)

was added dropwise, and the mixture was

stirred overnight at rt. TLC (2:1 petroleum

ether–EtOAc) indicated that the reaction was

complete. The mixture was concentrated un-

der reduced pressure to dryness. Puriﬁcation

by column chromatography (2:1 petroleum

ether–EtOAc) gave 8 (1002 mg, 75% for two

steps) as a colorless solid: mp 139–142 °C;

[h]_D−23.8° (c 2.0, CHCl₃). ¹H NMR

(CDCl₃): l 8.17–7.25 (m, 30 H, BzꢀH), 6.01

(m, 1 H, CH₂ꢁCHꢀCH₂ꢀ), 6.00–5.91 (m, 4 H,

H-4, H-4^I, H-3, H-1^II), 5.76 (dd, 1 H, J_1,21.7,

J_2,33.0 Hz, H-2), 5.70 (dd, 1 H, J_1,21.8 Hz,

H-2^I), 5.50 (d, 1 H, CH₂ꢁCHꢀCH₂ꢀ), 5.32 (d,

1 H, CH₂ꢁCHꢀCH₂ꢀ), 5.23–5.19 (m, 2 H,

H-3^I, H-4^II), 5.17 (d, 1 H, H-1) 5.13 (d, 1 H,

H-1^I), 5.10 (dd, 1 H, J_2,32.9, J_3,410.0 Hz,

H-3^II), 4.51 (dd, 1 H, J_1,21.6 Hz, H-2^II),

4.43–4.41 (m, 2 H, H-6_B, H-6^I_B), 4.24–4.06 (m,

5 H, H-5, H-5^I, H-6_A, H-6_A^I, H-6^I_B^I), 3.75 (dd, 1

H, CH₂ꢁCHꢀCH₂), 3.60–3.57 (m, 3 H, H-5^II,

H-6^I_A^I, CH₂ꢁCHꢀCH₂), 2.04 (s, 3 H, CH₃CO),

2.02 (s, 3 H, CH₃CO), 1.92 (s, 3 H, CH₃CO),

1.60 (s, 3 H, orthester CH₃). Anal. Calcd for

C₇₁H₆₈O₂₆: C, 63.77; H, 5.09. Found: C, 63.60;

H, 5.11.

osyl-(16)-2,3,4-tri-O-benzoyl-a- -manno-

D

pyranoside (6) (347 mg, 0.5 mmol) were dried

together under high vacuum for 2 h, then

dissolved in anhyd CH₂Cl₂(60 mL). TMSOTf

(10 mL, 0.10 equiv) was added dropwise at

−42 °C with N₂protection. The temperature

was gradually raised to ambient temperature,

and the reaction mixture was stirred totally

for 3 h, at the end of which time TLC (1:1.5

petroleum ether–EtOAc) indicated that the

reaction was complete. Then the mixture was

neutralized with Et₃N, and concentrated un-

der reduced pressure to dryness. Puriﬁcation

by column chromatography (1:1.5 petroleum

ether–EtOAc) gave 9 (487 mg, 65%) as a

colorless solid: [h]_D−26.7° (c 1.3, CHCl₃).

¹³C NMR (CDCl₃). l 170.53, 170.35, 170.10,

169.74, (4 CH₃CO), 166.01, 165.56, 165.48,

165.44, 165.36, 165.31, (6C₆H₅CO), 99.75,

97.08, 96.92, 96.71, (C-1^I–IV), 72.22, 71.02,

70.73, 70.55, 70.45, 69.88, 69.57, 69.49, 69.30,

69.21, 68.82, 68.63, 68.38, 67.14, 66.64, 66.46,

66.31, 65.87, 65.22, 62.26, (C-2,3,4,5,6^I–IV): H

1

NMR l 8.12–7.23 (m, 30 H, BzꢀH), 6.26 (t, 1

H, J_3,410.1 Hz, H-4^IIor H-4), 5.99 (m, 1 H,

CH₂ꢁCHꢀCH₂ꢀ), 5.92 (dd, 1 H, J_2,33.1, J_3,4

10.1 Hz, H-3^II, or H-3), 5.78–5.76 (m, 2 H),

5.73 (dd, 1 H, J_2,32.8, J_1,21.6 Hz, H-2^II, or

H-2), 5.41–5.36 (m, 2 H), 5.31 (dd, 1 H, J 2.7,

J 1.3 Hz), 5.27–5.24 (m, 3 H), 5.18 (d, 1 H, J

1.6 Hz), 5.06 (s, 1 H), 4.83 (d, 1 H, J 1.3 Hz),

4.74 (d, 1 H, J 1.3 Hz), (H-1, H-1^I, H-1^II,

H-1^III), 4.48 (d, 1 H), 4.39–4.32 (m, 2 H),

4.16–4.10 (m, 5 H), 4.00–3.97(m, 2 H), 3.91–

3.85 (m, 2 H), 3.79–3.60 (m, 5 H), 2.11 (s, 3

H, CH₃CO), 2.03 (s, 3 H, CH₃CO), 1.99 (s, 3

H, CH₃CO), 1.95 (s, 3 H, CH₃CO). Anal.

Calcd for C₇₇H₇₈O₃₁: C, 61.68; H, 5.21.

Found: C, 61.53; H, 5.26.

Preparation of 7 by rearrangement of 8.—A

solution of 8 (668 mg, 0.5 mmol) in anhyd

CH₂Cl₂(20 mL) was cooled to −5 to

−10 °C, then TMSOTf (5 mL) was added

under N₂ﬂow. The mixture was stirred at this

temperature for about 90 min, then neutral-

ized with Et₃N. After concentration under di-

minished pressure, the residue was subjected

to column chromatography to give a product

(601 mg, 90%) that was identical to 7.

Allyl 2,3,4,6 - tetra - O - acetyl - h -

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h -

mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-

h - - mannopyranosyl - (16) - 2,3,4 - tri - O-

benzoyl-h- -mannopyranoside (10).—To

D

- manno-

D

-

D

Allyl 2,3,4,6 - tetra - O - acetyl - h -

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h -

mannopyranosyl - (16) - h - - mannopyran-

osyl-(16)-2,3,4-tri-O-benzoyl-h- -manno-

pyranoside (9).—2,3,4,6-Tetra-O-acetyl-a-

mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-

a- -mannopyranosyl trichloroacetimidate (5)

D

- manno-

D

a

D

-

solution of 9 (300 mg, 0.2 mmol) in Py (10

mL), BzCl (0.1 mL, 0.86 mmol) was added

dropwise, and the mixture was stirred

overnight at rt. TLC (2:1 petroleum ether–

EtOAc) indicated that the reaction was com-

plete. The mixture was diluted with CH₂Cl₂,

D

-

D

10

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

h-

D

-mannopyranosyl

trichloroacetimidate

washed with 1 N HCl, water, and satd aq

NaHCO₃. The organic layer was combined,

dried, and concentrated. Puriﬁcation by

column chromatography (2:1 petroleum

ether–EtOAc) gave 10 quantitatively as a col-

orless solid: mp 143–146 °C; [h]_D−16.9° (c

(12).—To a solution of allyl 10 (905 mg, 0.5

mmol) in 90% AcOH (10 mL) containing

AcONa (293 mg, 3 mmol) was added PdCl₂

(89 mg, 0.5 mmol), and the mixture was

stirred for 12 h, at the end of which time TLC

(2:1 petroleum ether–EtOAc) indicated that

the reaction was complete. The mixture was

diluted with CH₂Cl₂(30 mL), washed with

water and satd aq NaHCO₃. The organic layer

was concentrated under reduced pressure, and

the residue thus obtained was passed a short

silica gel column with 2:1 petroleum ether–

EtOAc as the eluent to give crude 2,3,4,6-

1

1.3, CHCl₃). H NMR (CDCl₃): l 8.17–7.25

(m, 45 H, BzꢀH), 6.18 (t, 1 H, J 9.7 Hz), 6.10

(t, 1 H, J 9.6 Hz), 6.09–6.05 (m, 2 H), 6.04–

5.96 (m, 2 H), 5.94 (dd, 1 H, J 9.6, J 3.0 Hz),

5.88 (dd, 1 H, J 1.5, J 3.0 Hz), 5.79 (dd, 1 H,

J 1.7, J 3.2 Hz), 5.63 (dd, 1 H, J 1.6, J 2.8

Hz), 5.46 (d, 1 H, CH₂ꢁCHꢀCH₂), 5.36 (dd, 1

H, J 3.2, J 10.2 Hz), 5.28 (d, 1 H,

CH₂ꢁCHꢀCH₂), 5.25–5.21 (m, 2 H), 5.20 (s, 1

H) 4.84 (s, 1 H), 4.65 (d, 1 H, J 1.4 Hz,

H-1^III), 4.58–4.52 (m, 1 H), 4.49–4.42 (m, 1

H), 4.37–4.32 (m, 1 H), 4.28–4.22 (m, 2 H),

4.18–4.14 (m, 1 H), 4.06–4.01 (m, 1 H), 3.97–

3.92 (m, 1 H), 3.86–3.75 (m, 4 H), 3.74–3.71

(m, 1 H),3.45 (d, 1 H), 3.34 (d, 1 H), 2.10 (s,

3 H, CH₃CO), 2.04 (s, 3 H, CH₃CO), 1.98 (s,

3 H, CH₃CO), 1.90 (s, 3 H, CH₃CO). Anal.

Calcd for C₉₈H₉₀O₃₄: C, 64.97; H, 4.97.

Found: C, 64.93; H, 5.01.

tetra-O-acetyl-a-

2,3,4 - tri - O - benzoyl - a -

(16)-2,3,4-tri-O-benzoyl-a-

osyl-(16)-2,3,4-tri-O-benzoyl-

D

-mannopyranosyl-(16)-

- mannopyranosyl-

-mannopyran-

-manno-

D

pyranose (883 mg), which was dissolved in

CH₂Cl₂(20 mL), then CCl₃CN (0.1 mL, 2

mmol) and DBU (14 mL, 0.18 mmol) were

added. The reaction mixture was stirred for 2

h, at the end of which time TLC (2:1

petroleum ether–EtOAc) indicated that the

reaction was complete. Concentration of the

reaction mixture followed by puriﬁcation on a

silica gel column with 2:1 petroleum ether–

EtOAc as the eluent furnished the tetra-

saccharide donor 12 as crystals in a good yield

(823 mg, 86%): mp 136–139 °C; [h]_D−26.2°

Allyl

mannopyranosyl - (16) - h -

osyl-(16)-h- -mannopyranoside

h-

D

-mannopyranosyl-(16)-h-

- mannopyran-

(11).—

D

-

D

To the solution of 10 (181 mg, 0.1 mmol) in

CH₃OH (10 mL) was added dropwise

CH₃ONa (0.1 mL, 0.1 mmol), and the mixture

was stirred at rt for 12 h, at the end of which

time the reaction was complete as indicated by

TLC (2:1 MeOH–EtOAc). The solution was

neutralized with Amberlite-120 (H⁺), and

concentrated to give 11 (63.5 mg, 90%) as a

1

(c 1.4, CHCl₃). H NMR (CDCl₃): l 9.00 (s, 1

H, CꢁNꢀH), 8.14–7.25 (m, 45 H, BzꢀH), 6.62

(s, 1 H, H-1), 6.34 (t, 1 H, J 9.8 Hz, H-4),

6.05–5.89 (m, 5 H), 5.87–5.85 (m, 2 H), 5.49

(dd, 1 H, J 1.7, J 3.1 Hz), 5.37 (dd, 1 H, J

10.1, J 3.4 Hz), 5.27 (dd, 1 H, J 1.6, J 3.4 Hz),

5.23 (t, 1 H, J 10.0 Hz), 5.18 (d, 1 H, J 1.3

Hz), 4.80 (d, 1 H, J 1.3 Hz), 4.73–4.70 (m, 1

H), 4.67 (d, 1 H, J 1.4 Hz, H-1^III), 4.35–4.28

(m, 2 H), 4.15–4.11 (m, 1 H), 4.02–4.00 (m, 1

H), 3.92–3.90 (m, 2 H), 3.86–3.74 (m, 3 H),

3.39–3.35 (m, 2 H), 2.10 (s, 3 H, CH₃CO),

2.04 (s, 3 H, CH₃CO), 1.98 (s, 3 H, CH₃CO),

1.88 (s, 3 H, CH₃CO). Anal. Calcd for

C₉₇H₈₆Cl₃NO₃₄: C, 60.80; H, 4.49. Found: C,

60.75; H, 4.52.

13

colorless solid: [h]_D−46.9° (c 1.1, water). C

NMR (D₂O): l 100.85, 100.60, 100.38, 97.27

(C-1^I–IV), 73.76, 73.51, 73.33, 72.71, 71.22,

71.06, 70.87, 70.51, 69.04, 68.46, 67.48, 67.17,

66.63, 66.39, 66.17, 58.61 (C-2,3,4,5,6^I–IV

,

1

some signals overlapped): H NMR (D₂O): l

6.03–5.98 (m, 1 H, CH₂ꢁCHꢀCH₂), 5.39–5.28

(m, 2 H, CH₂ꢁCHꢀCH₂), 4.91–4.89 (4 H, H-1,

H-1^I, H-1^II, H-1^III), 4.21–3.66 (m, 26 H).

Anal. Calcd for C₂₇H₄₆O₂₁: C, 45.89; H, 6.52.

Found: C, 45.92; H, 6.51.

Allyl h -

tri - O - benzoyl - h -

2,3,4 - tri - O - benzoyl - h -

(16) - 2,3,4 - tri - O - benzoyl - h -

pyranoside (13).—To a solution of 10 (905

D

- mannopyranosyl - (16) - 2,3,4-

- mannopyranosyl - (16)-

- mannopyranosyl-

- manno-

2,3,4,6 - Tetra - O - acetyl - h -

osyl-(16)-2,3,4-tri-O-benzoyl-h-

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h -

mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-

D

- mannopyran-

D

-manno-

D

-

D

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

11

1

[h]_D−4.6° (c 0.8, CHCl₃). H NMR (CDCl₃):

l 8.07–7.20 (m, 60 H, BzꢀH), 6.30 (t, 1 H, J

9.7 Hz), 6.09–6.06 (m, 2 H), 6.00–5.95 (m, 2

H), 5.92–5.88 (m, 2 H), 5.81–5.78 (m, 4 H),

5.53 (dd, 1 H, J 1.4, J 2.8 Hz), 5.45 (dd, 1 H,

J 1.5, J 2.9 Hz), 5.40–5.38 (m, 2 H), 5.27–

5.22 (m, 3 H), 5.21 (s, 1 H), 5.19 (s, 1 H), 4.89

(s, 1 H), 4.84 (s, 1 H), 4.82 (s, 1 H), 4.77 (s, 1

H), (H-1, H-1^I, H-1^II, H-1^III, H-1^IV, H-1^V),

4.59–4.53 (m, 1 H), 4.42–4.33 (m, 3 H), 4.30–

4.17 (m, 4 H), 4.13–4.08 (m, 2 H), 4.05–3.86

(m, 7 H), 3.62–3.55 (m, 5 H), 3.50 (d, 1 H),

2.11 (s, 3 H, CH₃CO), 2.00 (s, 3 H, CH₃CO),

1.96 (s, 3 H, CH₃CO), 1.94 (s, 3 H, CH₃CO).

Anal. Calcd for C₁₃₁H₁₂₂O₄₇: C, 64.27; H,

4.99. Found: C, 64.03; H, 5.01.

mg, 0.5 mmol) in anhyd MeOH (50 mL) was

added AcCl (1.5 mL) at 0 °C. The solution

was sealed in a ﬂask and stirred for 10 h at rt,

and then another portion of AcCl (1 mL) was

added. The reaction was monitored by TLC

(1:2 petroleum ether–EtOAc) until the start-

ing material disappeared. The solution was

neutralized with Et₃N, then concentrated to

dryness. The residue was passed through a

short silica-gel column to give crystalline 13

(731 mg, 89%) which was directly used for the

next reaction: mp 145–148 °C; [h]_D−16.9° (c

1

1.4, CHCl₃). H NMR (CDCl₃): l 8.14–7.25

(m, 45 H, BzꢀH), 6.26 (t, 1 H, J 10.0 Hz),

6.06–6.94 (m, 5 H), 5.90 (dd, 1 H, J 1.4, J 3.3

Hz), 5.85 (dd, 1 H, J 2.8, J 10.1 Hz), 5.79 (dd,

1 H, J 1.6, J 3.3 Hz), 5.51 (dd, 1 H, J 1.7, J

2.9 Hz), 5.42 (d, 1 H, CH₂ꢁCHꢀCH₂), 5.24 (d,

1 H, CH₂ꢁCHꢀCH₂), 5.22 (d, 1 H, J 1.4 Hz),

5.20 (d, 1 H, J 1.6 Hz), 4.76 (d, 1 H, J 1.7 Hz),

(H-1, H-1^I, H-1^II), 4.74 (d, 1 H, J 1.5 Hz,

H-1^III), 4.53–4.57 (m, 1 H), 4.40–4.47 (dd, 1

H), 4.29–4.15 (m, 5 H), 3.92–3.83 (m, 5 H),

3.69–3.63 (m, 2 H), 3.47–3.34 (m, 3 H). Anal.

Calcd for C₉₀H₈₂O₃₀: C, 65.77; H, 4.99.

Found: C, 65.90; H, 5.04.

Allyl 2,3,4,6 - tetra - O - acetyl - h -

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h -

mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-

h - - mannopyranosyl - (16) - 2,3,4 - tri - O-

benzoyl - h - - mannopyranosyl - (16) - 2,3,4-

tri - O - benzoyl - h - - mannopyranosyl - (16)-

2,3,4 - tri - O - benzoyl - h - - mannopyranoside

D

- manno-

D

-

D

(15).—To a solution of 14 (122 mg, 0.05

mmol) in Py (5 mL), BzCl (0.1 mL, 18 mmol)

was added dropwise, and the mixture was

stirred overnight at rt. TLC (1.5:1 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 layers were

combined, dried, and concentrated. Puriﬁca-

tion by column chromatography (1.5:1

petroleum ether–EtOAc) gave 15 quantita-

tively as a colorless solid: [h]_D−6.3° (c 1.3,

Allyl 2,3,4,6 - tetra - O - acetyl - h -

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h -

mannopyranosyl - (16) - h - - mannopyran-

osyl-(16)-2,3,4-tri-O-benzoyl-h- -manno-

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h -

mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-

h - - mannopyranoside (14).—2,3,4,6 - Tetra-

O-acetyl-a- -mannopyranosyl-(16)-2,3,4-

tri - O - benzoyl - a - - mannopyranosyl tri-

D

- manno-

D

-

D

-

D

1

chloroacetimidate (5) (97 mg, 0.1 mmol) and

the tetrasaccharide acceptor 13 (164 mg, 0.1

mmol) were dried together under high vacuum

for 2 h, then dissolved in anhyd CH₂Cl₂(30

mL). TMSOTf (2 mL, 0.10 equiv) was added

dropwise at −42 °C with N₂protection. The

temperature of the reaction was gradually

raised to ambient temperature, and the mix-

ture was stirred for a total of 3 h, at the end

of which time TLC (1:1.5 petroleum ether–

EtOAc) indicated that the reaction was com-

plete. Then the mixture was neutralized with

Et₃N, and concentrated under reduced pres-

sure to dryness. Puriﬁcation by column chro-

matography (1:1.5 petroleum ether–EtOAc)

gave 14 (176 mg, 72%) as a colorless solid:

CHCl₃). H NMR (CDCl₃): l 8.16–7.20 (m,

75 H, BzꢀH), 6.28 (t, 1 H, J 9.8 Hz), 6.14–

6.07 (m, 4 H), 6.01–5.92 (m, 6 H), 5.79–5.68

(m, 4 H), 5.44–5.39 (m, 2 H), 5.29–5.21 (m, 4

H), 4.97 (s, 1 H), 4.95 (s, 1 H), 4.90 (s, 1 H),

4.89 (s, 1 H), 4.83 (s, 1 H), (H-1, H-1^I, H-1^II,

H-1^III, H-1^IV), 4.63 (s, 1 H, H-1^V), 4.56–4.52

(m, 1 H), 4.41–4.21 (m, 6 H), 4.06–3.90 (m, 7

H), 3.87–3.76 (m, 2 H), 3.63–3.51 (m, 2 H),

3.38–3.36 (m, 1 H), 3.20–3.17 (m, 1 H), 2.11

(s, 3 H, CH₃CO), 2.09 (s, 3 H, CH₃CO), 1.92

(s, 3 H, CH₃CO), 1.89 (s, 3 H, CH₃CO). Anal.

Calcd for C₁₅₂H₁₃₄O₅₀: C, 66.13; H, 4.86.

Found: C, 66.37; H, 4.82.

Allyl h -

D

- mannopyranosyl - (16) - h -

mannopyranosyl - (16) - h -

D

-

D

- mannopyran-

12

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

3 H, CH₃CO), 1.89 (s, 3 H, CH₃CO). Anal.

Calcd for C₁₈₅H₁₆₆O₆₃: C, 65.41; H, 4.89.

Found: C, 65.24; H, 4.85.

osyl-(16)-h-

D

-mannopyranosyl-(16)-h-

-mannopyran-

D

-mannopyranosyl-(16)-h-

D

oside (16).—A satd solution of NH₃in

MeOH (5 mL) was added to a solution of 15

(83 mg, 30 mmol) in MeOH (4 mL). After 48

h at rt, the reaction mixture was concentrated,

and the residue was puriﬁed by chromatogra-

phy on Sephadex LH-20 (MeOH) to afford 16

Allyl 2,3,4,6 - tetra - O - acetyl - h -

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h -

mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-

h - - mannopyranosyl - (16) - 2,3,4 - tri - O-

benzoyl - h - - mannopyranosyl - (16) - 2,3,4-

tri - O - benzoyl - h - - mannopyranosyl - (16)-

2,3,4 - tri - O - benzoyl - h - - mannopyranosyl-

(16)-2,3,4-tri-O-benzoyl-h- -mannopyran-

osyl-(16)-2,3,4-tri-O-benzoyl-h- -manno-

D

- manno-

D

-

D

1

(28 mg, 90%) as a syrup: H NMR (D₂O): l

D

6.01–5.93 (m, 1 H, CH₂ꢁCHꢀCH₂ꢀ), 5.37 (d,

D

1

H, CH₂ꢁCHꢀCH₂), 5.33 (d,

1

H,

D

CH₂ꢁCHCH₂), 4.93–4.89 (6 H, H-1), 4.25–

4.21 (dd, 1 H), 4.19–4.15 (dd, 1 H), 4.09–3.90

(m, 12 H), 3.85–3.69 (m, 24 H). Anal. Calcd

for C₃₉H₆₆O₃₁: C, 45.44; H, 6.41. Found: C,

45.58; H, 6.37.

D

pyranoside (18).—To a solution of 17 (119

mg, 0.035 mmol) in Py (5 mL), BzCl (0.1 mL,

24 mmol) was added dropwise, and the mix-

ture was stirred overnight at rt. TLC (1.5:1

petroleum ether–EtOAc) indicated that the

reaction was complete. The mixture was di-

luted with CH₂Cl₂, washed with 1 N HCl,

water, and satd aq NaHCO₃. The organic

layer was combined, dried, and concentrated.

Puriﬁcation by column chromatography (1.5:1

petroleum ether–EtOAc) gave 18 quantita-

tively as a colorless solid: [h]_D−14.1° (c 0.8,

Allyl 2,3,4,6 - tetra - O - acetyl - h -

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h -

mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-

h - - mannopyranosyl - (16) - 2,3,4 - tri - O-

benzoyl - h - - mannopyranosyl - (16) - h -

mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-

h - - mannopyranosyl - (16) - 2,3,4 - tri - O-

benzoyl - h - - mannopyranosyl - (16) - 2,3,4-

tri-O-benzoyl-h- -mannopyranoside (17).—

D

- manno-

D

-

D

-

D

13

CHCl₃). C NMR (CDCl₃): l 170.40, 169.70,

The tetrasaccharide donor 12 (191 mg, 0.1

mmol) and the tetrasaccharide acceptor 13

(164 mg, 0.1 mmol) were dried together under

high vacuum for 2 h, then dissolved in anhyd

CH₂Cl₂(30 mL). TMSOTf (1.5 mL, 0.08

equiv) was added dropwise at −42 °C with

N₂protection. The reaction mixture was

stirred for 3 h, during which time the reaction

temperature was gradually raised to ambient

temperature. Then the mixture was neutral-

ized with Et₃N, and concentrated under re-

duced pressure to an oily residue. Puriﬁcation

by column chromatography (1:1.5 petroleum

ether–EtOAc) gave 17 (210 mg, 62%) as a

colorless solid: mp 138–140 °C; [h]_D−32.0°

169.69, 169.33, (4 CH₃CO), 165.76, 165.56,

165.51, 165.55, 165.43, 165.40, 165.35, 165.35,

165.31, 165.25, 165.22, 165.10, (21C₆H₅CO,

some signals overlapped), 98.2, 98.1, 97.8,

97.7, 96.9, (C-1^I–VIIIsome signals overlapped),

70.63, 70.47, 70.33, 70.17, 69.30, 69.14, 66.42,

65.64, 61.96, (C-2,3,4,5,6^I–VIIIsome signals

1

overlapped). H NMR (CDCl₃): l 8.08–7.25

(m, 105 H, BzꢀH), 6.28–5.92 (m, 16 H), 5.85–

5.65 (m, 7 H), 5.46–5.35 (m, 2 H), 5.28–5.19

(m, 6 H), 5.02 (s, 1 H), 4.97 (s, 1 H), 4.89 (s,

1 H), 4.65 (s, 1 H, H-1^VII), 4.57–3.16 (m, 26

H), 2.09 (s, 3 H, CH₃CO), 2.04 (s, 3 H,

CH₃CO), 1.97 (s, 3 H, CH₃CO), 1.89 (s, 3 H,

CH₃CO). Anal. Calcd for C₂₀₆H₁₇₈O₆₆: C,

66.70; H, 4.80. Found: C, 66.53; H, 4.83.

1

(c 0.9, CHCl₃). H NMR (CDCl₃): l 8.20–

7.20 (m, 90 H, BzꢀH), 6.33 (t, 1 H, J 10.1 Hz),

6.15–5.80 (m, 15 H), 5.62 (dd, 1 H, J 1.4, J

2.7 Hz), 5.56 (dd, 1 H, J 1.4, J 2.8 Hz), 5.53

(dd, 1 H, J 1.5, J 2.8 Hz), 5.42 (d, 1 H,

CH₂ꢁCHꢀCH₂ꢀ), 5.37 (dd, 1 H, J 10.1, J 3.0

Hz), 5.26–5.18 (m, 6 H), 5.17 (s, 1 H), 4.96 (s,

1 H), 4.84 (s, 1 H), 4.79 (s, 1 H), 4.62 (s, 1 H),

4.60–4.56 (m, 2 H), 4.38–3.72 (m, 24 H), 3.50

(m, 1 H), 3.42 (m, 1 H), 3.30 (m, 1 H), 2.10 (s,

3 H, CH₃CO), 2.04 (s, 3 H, CH₃CO), 1.98 (s,

Allyl h -

mannopyranosyl - (16) - h -

osyl - (16) - h - - mannopyranosyl - (16)-

h - - mannopyranosyl - (16) - h - - manno-

pyranosyl - (16) - h - - mannopyranosyl-

(16)-h- -mannopyranoside (19).—A satd

D

- mannopyranosyl - (16) - h -

D

-

D

- mannopyran-

D

solution of NH₃in MeOH (5 mL) was added

to a solution of 18 (74 mg, 20 mmol) in MeOH

(4 mL). After 48 h at rt, the reaction mixture

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

13

osyl-(16)-2,3,4-tri-O-benzoyl-h-

D

-manno-

was concentrated, and the residue was puriﬁed

by chromatography on Sephadex LH-20

(MeOH) to afford 19 as a colorless solid (24.4

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h - -

D

mannopyranoside (21).—The tetrasaccharide

donor 12 (96 mg, 0.05 mmol) and the octasac-

charide acceptor 20 (177 mg, 0.05 mmol) were

dried together under high vacuum for 2 h,

then dissolved in anhyd CH₂Cl₂(20 mL). TMS-

OTf (1.5 mL, 0.16 equiv) was added dropwise

at −42 °C with N₂protection. The reaction

mixture was stirred for 3 h, during which time

the reaction temperature was gradually raised

to ambient temperature. Then the mixture was

neutralized with Et₃N, and concentrated un-

der reduced pressure to an oily residue. Puriﬁ-

cation by column chromatography (1:2

petroleum ether–EtOAc) gave 21 (122 mg,

46%) as a colorless solid: mp 122–125 °C; [h]_D

−4.1° (c 0.9, CHCl₃). MALDI-TOF–MS

Anal. Calcd for C₂₉₃H₂₅₄O₉₅: 5291.5 [M].

1

mg, 90%): H NMR (D₂O): l 6.05–5.97 (m, 1

H, CH₂ꢁCHꢀCH₂ꢀ), 5.40 (d,

1

H,

CH₂ꢁCHꢀCH₂), 5.33 (d, 1 H, CH₂ꢁCHꢀCH₂),

4.93–4.87 (8 H, H-1), 4.28–4.24 (dd, 1 H),

4.25–4.19 (dd, 2 H), 4.05–3.92 (m, 16 H),

3.90–3.67 (m, 31 H). Anal. Calcd for

C₅₁H₈₆O₄₁: C, 45.20; H, 6.35. Found: C, 45.16;

H, 6.40.

Allyl

tri - O - benzoyl - h -

2,3,4 - tri - O - benzoyl - h -

(16)-2,3,4-tri-O-benzoyl-h-

osyl-(16)-2,3,4-tri-O-benzoyl-h-

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h -

mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-

h - - mannopyranosyl - (16) - 2,3,4 - tri - O-

benzoyl-h- -mannopyranoside (20).—To a so-

h-D

-mannopyranosyl-(16)-2,3,4-

- mannopyranosyl - (16)-

- mannopyranosyl-

-mannopyran-

-manno-

D

-

D

1

D

Found: 5314 [M+Na], 5330 [M+K]: H

lution of 18 (371 mg, 0.1 mmol) in anhyd

MeOH (10 mL) was added AcCl (0.3 mL) at

0 °C. The solution was sealed in a ﬂask and

stirred for 10 h at rt, and then another portion

of AcCl (0.2 mL) was added. The reaction was

monitored by TLC (1:2 petroleum ether–

EtOAc) until the starting material disap-

peared. The solution was neutralized with

Et₃N, then concentrated to dryness. The

residue was passed through a short silica-gel

column to give crystalline 20 (290 mg, 82%)

that was directly used for the next reaction:

mp 143–146 °C; [h]_D−12.9° (c 1.4, CHCl₃).

¹H NMR (CDCl₃): l 8.06–7.24 (m, 105 H,

BzꢀH), 6.25–5.94 (m, 14 H), 5.82–5.64 (m, 7

H), 5.42–5.33 (m, 2 H), 5.30–5.21 (m, 5 H),

5.05 (s, 1 H), 5.00 (s, 1 H), 4.93 (s, 1 H), 4.69

(s, 1 H, H-1^VII), 4.60–3.12 (m, 29 H). Anal.

Calcd for C₁₉₈H₁₇₀O₆₂: C, 66.16; H, 4.80.

Found: C, 66.33; H, 4.83.

NMR (CDCl₃): l 8.16–7.22 (m, 150 H,

BzꢀH), 6.26–5.70 (m, 30 H), 5.40–5.21 (m, 8

H), 4.96–3.20 (m, 51 H), 2.15 (s, 3 H,

CH₃CO), 2.10 (s, 3 H, CH₃CO), 1.98 (s, 3 H,

CH₃CO), 1.89 (s, 3 H, CH₃CO). Anal. Calcd

for C₂₉₃H₂₅₄O₉₅: C, 66.47; H, 4.80. Found: C,

66.64; H, 4.82.

Allyl 2,3,4,6 - tetra - O - acetyl - h -

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h -

mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-

h - - mannopyranosyl - (16) - 2,3,4 - tri - O-

benzoyl - h - - mannopyranosyl - (16) - 2,3,4-

tri - O - benzoyl - h - - mannopyranosyl - (16)-

2,3,4 - tri - O - benzoyl - h - - mannopyranosyl-

(16)-2,3,4-tri-O-benzoyl-h- -mannopyran-

osyl-(16)-2,3,4-tri-O-benzoyl-h- -manno-

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h -

mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-

h - - mannopyranosyl - (16) - 2,3,4 - tri - O-

benzoyl - h - - mannopyranosyl - (16) - 2,3,4-

tri-O-benzoyl-h- -mannopyranoside (22).—

D

- manno-

D

-

D

-

D

Allyl 2,3,4,6 - tetra - O - acetyl - h -

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h -

mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-

h - - mannopyranosyl - (16) - 2,3,4 - tri - O-

benzoyl - h - - mannopyranosyl - (16) - h -

mannopyranosyl-(16)-2,3,4-tri-O-benzoyl-

h - - mannopyranosyl - (16) - 2,3,4 - tri - O-

benzoyl - h - - mannopyranosyl - (16) - 2,3,4-

tri - O - benzoyl - h - - mannopyranosyl - (16)-

2,3,4 - tri - O - benzoyl - h - - mannopyranosyl-

(16)-2,3,4-tri-O-benzoyl-h- -mannopyran-

D

- manno-

D

-

To a solution of 21 (106 mg, 0.02 mmol) in Py

(5 mL) BzCl (0.1 mL, 24 mmol) was added

dropwise, and the mixture was stirred over-

night at rt. TLC (1.5:1 petroleum ether–

EtOAc) indicated that the reaction was com-

plete. 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 (1:1 petroleum

D

-

D

14

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

mg, 4 mmol) and allyl a- -glucopyranoside

D

ether–EtOAc) gave 22 (103 mg, 92%) as a

13

(25) (880 mg, 4 mmol) were dried together

under high vacuum for 0.5 h, then dissolved in

anhyd DMF (60 mL). TMSOTf (30 mL, 0.04

equiv) was added dropwise at −42 °C with

N₂protection. The reaction mixture was

stirred for 0.5 h. Then the mixture was neu-

tralized with Et₃N and concentrated under

reduced pressure to dryness. To the solution

of the residue in Py (20 mL), BzCl (1.4 mL, 12

mmol) was added dropwise, and the mixture

was stirred overnight at rt. TLC (2:1

petroleum ether–EtOAc) indicated that the

reaction was complete. Then the mixture was

concentrated under reduced pressure to dry-

ness. Puriﬁcation by column chromatography

(2:1 petroleum ether–EtOAc) gave 26 (2414

mg, 70% for two steps) as a colorless solid:

colorless solid: [h]_D−6.5° (c 0.6, CHCl₃). C

NMR (CDCl₃): l 170.33, 169.80, 169.80,

169.47, (4 CH₃CO), 166.74, 166.34, 165.98,

165.86, 165.80, 165.79, 165.78, 165.76, 165.70,

165.68, 165.65, 165.63, 165.60, 165.59, 165.55,

165.52, 165.48, 165.45, 165.43, 165.40, 165.37,

165.35, 165.32, 165.31, 165.22, 165.10,

(33C₆H₅CO, some signals overlapped), 98.37,

98.34, 98.29, 98.10, 98.03, 97.88, 97.46, 97.40,

97.33, (C-1^I–XIIsome signals overlapped),

70.64, 70.62, 70.61, 70.59, 70.55, 70.52, 70.44,

70.38, 70.33, 70.30, 70.24, 70.19, 69.97, 69.90,

69.84, 69.80, 69.70, 69.62, 69.59, 69.20, 69.11,

67.86, 67.80, 67.73, 67.65, 67.37, 67.19, 66.89,

66.73, 66.58, 66.50, 66.42, 66.29, 66.07, 65.78,

63.98, 63.80, 63.57, 63.29, 62.77, 62.37, 62.07,

61.73, 61.50, 61.40, (C-2,3,4,5,6^I–XIIsome sig-

nals overlapped); MALDI-TOF–MS Anal.

Calcd for C₃₁₄H₂₆₆O₉₈: 5603.6 [M]. Found:

1

[h]_D+3.6° (c 1.4, CHCl₃). H NMR (CDCl₃):

l 7.98–7.26 (m, 15 H, BzꢀH), 6.14 (t, 1 H, J_2,3

10.0, J_3,410.0 Hz, H-3), 5.95–5.89 (m, 1 H,

CH₂ꢁCHꢀCH₂ꢀ), 5.74 (d, 1 H, J_1,25.2 Hz,

H-1^I), 5.55 (t, 1 H, H-4), 5.37–5.27 (m, 3 H,

H-4^I, H-1, CH₂ꢁCHCH₂ꢀ), 5.18 (dd, 1 H,

CH₂ꢁCHꢀCH₂ꢀ), 5.15 (dd, 1 H, J_1,23.1 Hz,

H-2), 4.89 (dd, 1 H, J_2,33.0, J_3,49.5 Hz, H-3^I),

4.33 (dd, 1 H, H-2^I), 4.30–4.17 (m, 4 H),

4.10–4.06 (m, 1 H), 3.97–3.94 (m, 1 H), 3.69–

3.67 (m, 2 H), 2.10 (s, 3 H, CH₃CO), 2.08 (s,

3 H, CH₃CO), 2.00 (s, 3 H, CH₃CO), 1.69 (s,

3 H, orthester CH₃). Anal. Calcd for

C₄₄H₄₆O₁₈: C, 61.25; H, 5.34. Found: C, 61.52;

H, 5.27.

1

5601.8 [M]. H NMR (CDCl₃): l 8.16–7.22

(m, 165 H, BzꢀH), 6.30–5.70 (m, 35 H), 5.42–

5.22 (m, 6 H), 5.00–4.85 (m, 4 H), 4.70–3.30

(m, 44 H), 2.11 (s, 3 H, CH₃CO), 2.05 (s, 3 H,

CH₃CO), 1.98 (s, 3 H, CH₃CO), 1.90 (s, 3 H,

CH₃CO). Anal. Calcd for C₃₁₄H₂₆₆O₉₈: C,

66.26; H, 4.75. Found: C, 66.19; H, 4.82.

Allyl

mannopyranosyl - (16) - h -

osyl - (16) - h - - mannopyranosyl - (16)-

h - - mannopyranosyl - (16) - h - - manno-

pyranosyl - (16) - h - - mannopyranosyl-

(16) - h - - mannopyranosyl - (16) - h -

mannopyranosyl - (16) - h - - mannopyran-

osyl - (16) - h - - mannopyranosyl - (16)-

h- -mannopyranoside (23).—A satd solution

h-D

-mannopyranosyl-(16)-h-

D

-

D

- mannopyran-

D

-

D

Allyl 2,3,4,6-tetra-O-acetyl-i-

osyl-(16)-2,3,4-tri-O-benzoyl-h-

pyranoside (27).—2,3,4,6-Tetra-O-acetyl-h-

glucopyranosyl trichloroacetimidate (24) (1972

mg, 4 mmol) and allyl a- -glucopyranoside

D

-glucopyran-

-gluco-

D

-

of NH₃in MeOH (5 mL) was added to a

solution of 22 (112 mg, 20 mmol) in MeOH (4

mL). After 48 h at rt, the reaction mixture was

concentrated, and the residue was puriﬁed by

chromatography on Sephadex LH-20 (MeOH)

D

(25) (880 mg, 4 mmol) were dried together

under high vacuum for 2 h, then dissolved in

anhyd DMF (60 mL). TMSOTf (60 mL, 0.08

equiv) was added dropwise at −42 °C with

N₂protection. The reaction mixture was

stirred for 3 h, during which time the tempera-

ture was gradually raised to ambient tempera-

ture. Then the mixture was neutralized with

Et₃N, and concentrated under reduced pres-

sure to afford crude allyl 2,3,4,6-tetra-O-ace-

1

to afford 23 (29 mg, 72%) as a syrup: H

NMR (D₂O):

l

6.00–5.92 (m,

1

H,

CH₂ꢁCHꢀCH₂ꢀ), 5.38 (d, 1 H, CH₂ꢁCHꢀ

CH₂), 5.32 (d, 1 H, CH₂ꢁCHꢀCH₂), 4.88–4.82

(12 H, H-1), 4.30–4.26 (m, 2 H), 4.22–4.17

(m, 3 H), 3.98–3.80 (m, 25 H), 3.78–3.60 (m,

44 H). Anal. Calcd for C₇₅H₁₂₆O₆₁: C, 44.96;

H, 6.29. Found: C, 44.92; H, 6.33.

tyl-b-

D

-glucopyranosyl-(16)-a- -glucopy-

D

Orthoester 26.—2,3,4,6-Tetra-O-acetyl-b-

D

-

ranoside. To the solution of the crude product

in Py (20 mL), BzCl (1.4 mL, 12 mmol) was

glucopyranosyl trichloroacetimidate (24) (1972

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

15

glucopyranose (741 mg) was dissolved in

CH₂Cl₂(20 mL), then CCl₃CN (0.2 mL, 2

mmol) and DBU (27 mL, 0.18 mmol) were

added. The reaction mixture was stirred for 2

h and the disaccharide donor 28 was obtained

as crystals in a good yield (841 mg, 87% for

two steps): mp 147–150 °C; [h]_D+1.5° (c 1.3,

added dropwise, and the mixture was stirred

overnight at rt. TLC (2:1 petroleum ether–

EtOAc) indicated that the reaction was com-

plete. The mixture was diluted with CH₂Cl₂

(30 mL), washed with water and satd aq

NaHCO₃. The organic layer was combined,

dried, and concentrated. Puriﬁcation by

column chromatography (2:1 petroleum

ether–EtOAc) gave 27 (2241 mg, 65% for two

steps) as a colorless solid: mp 156–158 °C;

[h]_D+24.1° (c 1.3, CHCl₃). ¹H NMR

(CDCl₃): l 7.98–7.26 (m, 15 H, BzꢀH), 6.16

(t, 1 H, J_2,39.8, J_3,49.8 Hz,, H-3), 5.85 (m, 1

H, CH₂ꢁCHꢀCH₂ꢀ), 5.43 (t, 1 H, J_4,59.8 Hz,

H-4), 5.37–5.28 (m, 2 H, H-1, H-2), 5.26–5.17

(m, 3 H, CH₂ꢁCHꢀCH₂, H-2^I, H-3^I), 5.08–

5.05 (m, 2 H, CH₂ꢁCHꢀCH₂, H-4^I), 4.57 (d, 1

H, J_1,27.9 Hz, H-1^I), 4.30–4.20 (m, 3 H),

4.08–4.03 (m, 3 H), 3.71–3.67 (m, 2 H), 2.10

(s, 3 H, CH₃CO), 2.04 (s, 9 H, 3CH₃CO).

Anal. Calcd for C₄₄H₄₆O₁₈: C, 61.25; H, 5.34.

Found: C, 61.20; H, 5.39.

Preparation of 27 by rearrangement of 26.—

A solution of 26 (862 mg, 1 mmol) in anhyd

CH₂Cl₂(20 mL) was cooled to −5 to

−10 °C, then TMSOTf (5 mL) was added

under N₂ﬂow. The mixture was stirred at this

temperature for about 90 min, then neutral-

ized with Et₃N. After concentration under di-

minished pressure, the residue was subjected

to column chromatography to give a product

(776 mg, 90%) that was identical to 27.

1

CHCl₃). H NMR (CDCl₃): l 8.60 (s, 1 H,

CꢁNH), 8.14–7.26 (m, 15 H, BzꢀH), 6.65 (d,

1 H, J_1,23.6 Hz, H-1), 6.24 (t, 1 H, J_2,39.8, J_3,4

9.8 Hz, H-3), 5.60 (t, 1 H, J_4,59.7 Hz, H-4),

5.53 (dd, 1 H, H-2), 5.19 (t, J_2,39.7, J_3,49.7

Hz, H-3^I), 5.08–4.95 (m, 2 H, H-4^I, H-2^I),

4.60 (d, 1 H, J_1,27.9 Hz, H-1^I), 4.49–4.44 (m,

1 H), 4.25–4.20 (m, 2 H), 4.11–4.05 (m, 2 H),

3.67–3.64 (m, 1 H), 2.08 (s, 3 H, CH₃CO),

2.05 (s, 3 H, CH₃CO), 2.02 (s, 3 H, CH₃CO),

1.97 (s, 3 H, CH₃CO). Anal. Calcd for

C₄₃H₄₂Cl₃NO₁₈C, 53.39; H, 4.35. Found: C,

53.55; H, 4.39.

Allyl i-

O-benzoyl-h-

solution of allyl 2,3,4,6-tetra-O-acetyl-b-

glucopyranosyl-(16)-2,3,4-tri-O-benzoyl-a-

-glucopyranoside (27) (862 mg, 1 mmol) in

D

-glucopyranosyl-(16)-2,3,4-tri-

D

-glucopyranoside (29).—To a

D

-

D

anhyd MeOH (50 mL) was added AcCl (1.5

mL) at 0 °C. The solution was sealed in a ﬂask

and stirred for 10 h at rt, and then another

portion of AcCl (1 mL) was added. The reac-

tion was monitored by TLC until the starting

material disappeared. The solution was neu-

tralized with Et₃N, then concentrated to dry-

ness. The residue was passed through a short

silica-gel column to give 29 (611 mg, 88%)

that was directly used for the next reaction:

mp 161–164 °C; [h]_D−18.0° (c 1.4, CHCl₃).

¹H NMR (CDCl₃): l 7.98–7.26 (m, 15 H,

BzꢀH), 6.20 (t, 1 H, J_2,39.8, J_3,49.8 Hz, H-3),

5.90–5.80 (m, 2 H, H-4, CH₂ꢁCHCH₂ꢀ), 5.41

(dd, 1 H, CH₂ꢁCHꢀCH₂ꢀ), 5.36–5.30 (m, 2 H,

H-2, H-1), 5.17–5.15 (dd, 1 H, CH₂ꢁCHꢀ

CH₂ꢀ), 4.50 (d, 1 H, J_1,27.9 Hz, H-1^I), 4.49–

4.18 (m, 3 H), 4.10–4.04 (m, 2 H), 3.92–3.78

(m, 2 H), 3.70–3.48 (m, 4 H). Anal. Calcd for

C₃₆H₃₈O₁₄: C, 62.25; H, 5.48. Found: C, 62.36;

H, 5.50.

2,3,4,6-Tetra-O-acetyl-i-

(16)-2,3,4-tri-O-benzoyl-h-

osyl trichloroacetimidate (28).—To a solution

of allyl 2,3,4,6-tetra-O-acetyl-b- -glucopyran-

osyl-(16)-2,3,4-tri-O-benzoyl-a- -gluco-

D

-glucopyranosyl-

D

-glucopyran-

D

pyranoside (27) (862 mg, 1 mmol) in 90%

AcOH (10 mL) containing AcONa (293 mg, 3

mmol) was added PdCl₂(89 mg, 0.5 mmol),

and the mixture was stirred for 12 h, at the

end of which time TLC (2:1 petroleum ether–

EtOAc) indicated that the reaction was com-

plete. The mixture was diluted with CH₂Cl₂

(30 mL), washed with water and satd aq

NaHCO₃. The organic layer was concentrated

under reduced pressure, and the residue was

passed through a short silica-gel column with

2:1 petroleum ether–EtOAc as the eluent. The

Allyl 2,3,4,6-tetra-O-acetyl-i-

osyl-(16)-2,3,4-tri-O-benzoyl-i-

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h -

glucopyranoside (30).—2,3,4,6-Tetra-O-acetyl-

a- -glucopyranosyl trichloroacetimidate (24)

D

-glucopyran-

D

-gluco-

D

-

obtained crude 2,3,4,6-tetra-O-acetyl-b-

D

-glu-

copyranosyl - (16) - 2,3,4 - tri - O - benzoyl -

D

-

D

16

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

170.55, 169.41, 169.41 (4 CH₃CO), 166.07,

165.77, 165.68, 165.68, 165.40, 165.38 (6

C₆H₅CO), 103.29, 101.75, 100.20, 97.30 (C-1^I–

IV), 75.36, 75.33, 73.60, 73.11, 72.71, 71.89,

71.83, 71.69, 71.51, 70.49, 69.68, 69.53, 68.65,

68.51, 68.51, 67.89, 67.60, 67.30, 62.81, 61.93

(493 mg, 1 mmol) and allyl b-

D

-glucopyran-

-gluco-

osyl-(16)-2,3,4-tri-O-benzoyl-a-

D

pyranoside (29) (694 mg, 1 mmol) were dried

together under high vacuum for 2 h, then

dissolved in anhyd CH₂Cl₂(60 mL). TMSOTf

(15 mL, 0.08 equiv) was added dropwise at

−42 °C with N₂protection. The reaction mix-

ture was stirred for 3 h. Then the mixture was

neutralized with Et₃N, and concentrated un-

der reduced pressure to an oily residue. To the

solution of the residue in Py (20 mL) was

added dropwise BzCl (0.35 mL, 3 mmol), and

the mixture was stirred overnight at rt. TLC

(2:1 petroleum ether–EtOAc) indicated that

the reaction was complete. The mixture was

diluted with CH₂Cl₂(30 mL), washed with

water and satd aq NaHCO₃. The organic layer

was combined, dried, and concentrated.

Puriﬁcation by column chromatography (2:1

petroleum ether–EtOAc) gave 30 (962 mg,

72% for two steps) as a colorless solid: [h]_D

1

(C-2,3,4,5,6^I–IV). H NMR (CDCl₃): l 7.99–

7.26 (m, 30 H, BzꢀH), 6.17 (t, 1 H, J 9.9 Hz),

5.92 (t, 1 H, J 9.7 Hz), 5.83 (m, 1 H,

CH₂ꢁCHꢀCH₂ꢀ), 5.78 (t, 1 H, J 9.9 Hz), 5.53

(dd, 1 H, J 8.1, J 9.8 Hz), 5.38–5.32 (m, 3 H),

5.28–5.23 (m, 3 H), 5.17–5.14 (dd, 1 H,

CH₂ꢁCHꢀCH₂), 5.07 (t, 1 H, J 8.1 Hz), 5.04

(d, 1 H, J 8.0 Hz), 5.02–4.95 (m, 2 H),

4.26–4.17 (m, 4 H), 4.09–4.01 (m, 3 H), 3.97–

3.87 (m, 2 H), 3.86–3.72 (m, 2 H), 3.71–3.66

(m, 1 H), 3.60–3.55 (m, 2 H), 3.53–3.45 (m, 1

H), 3.43 (t, 1 H, J 8.5 Hz), 3.39–3.37 (m, 1

H), 2.03 (s, 3 H, CH₃CO), 2.00 (s, 3 H,

CH₃CO), 1.99 (s, 3 H, CH₃CO), 1.95 (s, 3 H,

CH₃CO). Anal. Calcd for C₇₇H₇₈O₃₁: C, 61.68;

H, 5.21. Found: C, 61.43; H, 5.26.

1

+1.9° (c 1.4, CHCl₃). H NMR (CDCl₃): l

7.94–7.26 (m, 30 H, BzꢀH), 6.07–5.86 (m, 3

H), 5.44–5.23 (m, 5 H), 5.14–4.89 (m, 5 H),

4.88 (d, 1 H, J 7.7 Hz), 4.67 (d, 1 H, J 7.9 Hz),

4.22–4.16 (m, 3 H), 4.11–3.99 (m, 3 H), 3.79–

3.69 (m, 5 H), 2.05 (s, 3 H, CH₃CO), 2.04 (s,

3 H, CH₃CO), 2.00 (s, 3 H, CH₃CO), 1.97(s, 3

H, CH₃CO). Anal. Calcd for C₇₁H₆₈O₂₆: C,

63.77; H, 5.09. Found: C, 63.67; H, 5.12.

Allyl 2,3,4,6-tetra-O-acetyl-i-

osyl-(16)-2,3,4-tri-O-benzoyl-i-

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - i -

glucopyranosyl-(16)-2,3,4-tri-O-benzoyl-h-

-glucopyranoside (32).—To the solution of

D

-glucopyran-

-gluco-

D

-

D

31 (300 mg, 0.2 mmol) in Py (10 mL), BzCl

(0.1 mL, 0.86 mmol) was added dropwise, and

the mixture was stirred overnight at rt. TLC

(2:1 petroleum ether–EtOAc) indicated that

the reaction was complete. The mixture was

diluted with CH₂Cl₂(30 mL), washed with

water and satd aq NaHCO₃. The organic layer

was combined, dried, and concentrated.

Column chromatography (2:1 petroleum

ether–EtOAc) gave 32 quantitatively as a col-

Allyl 2,3,4,6-tetra-O-acetyl-i-

osyl-(16)-2,3,4-tri-O-benzoyl-i-

pyranosyl-(16)-i- -glucopyranosyl-(16)-

2,3,4-tri-O-benzoyl-h- -glucopuranoside (31).

—2,3,4,6-Tetra-O-acetyl-b- -glucopyranosyl-

(16)-2,3,4-tri-O-benzoyl-a- -glucopyran-

osyl trichloroacetimidate (28) (483 mg, 0.5

mmol) and allyl b- -glucopyranosyl-(16)-

2,3,4-tri-O-benzoyl-a- -glucopyranoside (29)

D

-glucopyran-

D

-gluco-

D

1

D

orless solid: [h]_D+4.8° (c 1.4, CHCl₃). H

D

NMR (CDCl₃): l 8.10–7.46 (m, 45 H, BzꢀH),

6.20 (t, 1 H, J 9.8 Hz), 5.99 (t, 1 H, J 9.6 Hz),

5.87–5.80 (m, 2 H), 5.76 (t, 1 H, J 9.6 Hz),

5.45 (t, 1 H, J 8.6 Hz), 5.38–4.96 (m, 10 H),

4.80 (d, 1 H, J 7.9 Hz), 4.72 (d, 1 H, J 7.8 Hz),

4.57 (dd, 1 H, J 9.7, J 7.9 Hz), 4.23–4.05 (m,

8 H), 3.80–3.62 (m, 6 H). 2.03 (s, 3 H,

CH₃CO), 2.01 (s, 3 H, CH₃CO), 2.00 (s, 3 H,

CH₃CO), 1.99 (s, 3 H, CH₃CO). Anal. Calcd

for C₉₈H₉₀O₃₄: C, 64.97; H, 4.97. Found: C,

64.89; H, 5.04.

(347 mg, 0.5 mmol) were dried together under

high vacuum for 2 h, then dissolved in anhyd

CH₂Cl₂(60 mL). TMSOTf (10 mL, 0.10 equiv)

was added dropwise at −42 °C with N₂pro-

tection. The reaction mixture was stirred for 3

h. Then the mixture was neutralized with

Et₃N, and concentrated under reduced pres-

sure to afford the crude product. Puriﬁcation

by column chromatography (1:1.5 petroleum

ether–EtOAc) gave 31 (487 mg, 65%) as a

colorless solid: mp 151–152 °C; [h]_D+12.0°

(c 1.3, CHCl₃). ¹³C HMR (CDCl₃): l 170.61,

i-

D

-Glucopyranosyl-(16)-i-

D

-glucopy-

ranosyl-(16)-i-

D

-glucopyranosyl-(16)- -

D

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

17

in CH₂Cl₂(20 mL), then CCl₃CN (0.1 mL, 2

mmol) and DBU (14 mL, 0.18 mmol) were

added. The reaction mixture was stirred for 2

h, at the end of which time TLC (2:1

petroleum ether–EtOAc) indicated that the

reaction was complete. Concentration of the

reaction mixture followed by puriﬁcation on a

silica-gel column with 2:1 petroleum ether–

EtOAc as the eluent gave the tetrasaccharide

donor 34 as crystals in a good yield (862 mg,

90%): mp 129–131 °C; [h]_D+4.8° (c 1.4,

glucopyranose (33).—To a solution of 32 (72

mg, 40 mmol) in 90% AcOH (1 mL) contain-

ing AcONa (29.3 mg, 0.3 mmol) was added

PdCl₂(8.9 mg, 0.5 mmol), and the mixture

was stirred for 12 h, at the end of which time

TLC (2:1 petroleum ether–EtOAc) indicated

that the reaction was complete. The mixture

was diluted with CH₂Cl₂(30 mL), washed

with water and satd aq NaHCO₃. The organic

layer was concentrated under reduced pres-

sure, and the residue was passed through a

short silica-gel column with 2:1 petroleum

ether–EtOAc as the eluent to give crude

1

CHCl₃). H NMR (CDCl₃): l 9.02 (s, 1 H,

CꢁNꢀH), 8.13–7.26 (m, 45 H, BzꢀH), 6.62 (s,

1 H, H-1), 6.21 (t, 1 H, J 9.8 Hz), 5.95 (t, 1 H,

J 9.6 Hz), 5.92–5.85 (m, 2 H), 5.60 (t, 1 H, J

9.6 Hz), 5.57 (t, 1 H, J 8.0 Hz), 5.52 (dd, 1 H,

J 9.7, J 7.9 Hz), 5.40–5.10 (m, 5 H), 5.05 (d,

1 H, J 7.9 Hz), 5.01 (d, 1 H, J 7.8 Hz), 4.95 (d,

1 H, J 7.9 Hz), 4.25–4.15 (m, 3 H), 4.07–3.90

(m, 3 H), 3.80–3.70 (m, 2 H), 3.65–3.54 (m, 2

H), 3.50–3.46 (m, 2 H), 2.05 (s, 3 H, CH₃CO),

2.03 (s, 3 H, CH₃CO), 2.01 (s, 3 H, CH₃CO),

1.99 (s, 3 H, CH₃CO). Anal. Calcd for

C₉₇H₈₆Cl₃NO₃₄C, 60.80; H, 4.49. Found: C,

60.63; H, 4.53.

2,3,4,6 - tetra - O - acetyl - b -

(16)-2,3,4-tri-O-benzoyl-b-

osyl-(16)-2,3,4-tri-O-benzoyl-b-

pyranosyl-(16)-2,3,4-tri-O-benzoyl-

D

- glucopyranosyl-

-glucopyran-

-gluco-

D

pyranose (65 mg), which was dissolved in a

satd solution of NH₃in MeOH (5 mL). After

48 h at rt, the reaction mixture was concen-

trated, and the residue was puriﬁed by chro-

matography on Sephadex LH-20 (MeOH) to

1

afford 33 (20.8 mg, 78%) as a syrup: H NMR

(D₂O): l 4.74 (s,1 H, H-1), 4.48 (d, 1 H, J 8.1

Hz), 4.46 (d, 1 H, J 8.0 Hz), 4.43 (d, 1 H, J 8.1

Hz), 3.98–3.75 (m, 8 H), 3.62–3.52 (m, 12 H),

Allyl i-

O-benzoyl-i-

tri - O - benzoyl - i -

2,3,4-tri-O-benzoyl-h-

D

-glucopyranosyl-(16)-2,3,4-tri-

-glucopyranosyl-(16)-2,3,4-

- glucopyranosyl - (16)-

-glucopyranoside (35).

3.36–3.30 (m,

4

H). Anal. Calcd for

D

C₂₄H₄₂O₂₁: C, 43.24; H, 6.31. Found: C, 43.17;

H, 6.35.

D

Allyl 2,3,4,6-tetra-O-acetyl-i-

osyl-(16)-2,3,4-tri-O-benzoyl-i-

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - i -

glucopyranosyl-(16)-2,3,4-tri-O-benzoyl-h-

-glucopyranosyl trichloroacetimidate (34).—

D

-glucopyran-

—To a solution of 32 (905 mg, 0.5 mmol) in

anhyd MeOH (50 mL) was added AcCl (1.5

mL) at 0 °C. The solution was sealed in a ﬂask

and stirred for 10 h at rt, and then another

portion of AcCl (1 mL) was added. The reac-

tion was monitored by TLC (1:2 petroleum

ether–EtOAc) until the starting material dis-

appeared. The solution was neutralized with

Et₃N, then concentrated to dryness. The

residue was passed through a short silica-gel

column to give 35 as a colorless solid (698 mg,

85%) that was directly used for the next reac-

D

-gluco-

D

-

D

To a solution of 32 (905 mg, 0.5 mmol) in

90% AcOH (10 mL) containing AcONa (293

mg, 3 mmol) was added PdCl₂(89 mg, 0.5

mmol), and the mixture was stirred for 12 h,

at the end of which time TLC (2:1 petroleum

ether–EtOAc) indicated that the reaction was

complete. The mixture was diluted with

CH₂Cl₂(30 mL), washed with water and satd

aq NaHCO₃. The organic layer was concen-

trated under reduced pressure, and the residue

was passed a short silica gel column with 2:1

petroleum ether–EtOAc as the eluent to give

1

tion: [h]_D+7.6° (c 1.4, CHCl₃). H NMR

(CDCl₃): l 8.15–7.25 (m, 45 H, BzꢀH), 6.18

(t, 1 H, J 9.9 Hz), 5.98 (t, 1 H, J 9.7 Hz),

5.95–5.87 (m, 2 H), 5.80 (t, 1 H, J 9.8 Hz),

5.59 (t, 1 H, J 8.1 Hz), 5.48 (dd, 1 H, J 9.8, J

7.9 Hz), 5.35–5.25 (m, 3 H), 5.18–5.09 (m, 3

H), 5.04 (d, 1 H, J 7.8 Hz), 4.99 (d, 1 H, J 7.7

Hz), 4.96 (d, 1 H, J 7.9 Hz), 4.60–4.50 (m, 3

H), 4.41–4.16 (m, 9 H), 3.98–3.87 (m, 3 H),

crude 2,3,4,6-tetra-O-acetyl-b-

D

-glucopyran-

-glucopy-

osyl-(16)-2,3,4-tri-O-benzoyl-b-

D

ranosyl-(16)-2,3,4-tri-O-benzoyl-b-

D

-gluco-

pyranosyl-(16)-2,3,4-tri-O-benzoyl-

D

pyranose (860 mg). The product was dissolved

18

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

and the mixture was stirred overnight at rt.

3.60–3.51 (m,

C₉₀H₈₂O₃₀: C, 65.77; H, 4.99. Found: C, 65.62;

H, 5.03.

2

H). Anal. Calcd for

TLC (1.5:1 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 or-

ganic layer was combined, dried, and concen-

trated. Puriﬁcation by column chromato-

graphy (1.5:1 petroleum ether–EtOAc) gave

37 (135 mg, 98%) as a colorless solid: mp

Allyl 2,3,4,6-tetra-O-acetyl-i-

osyl-(16)-2,3,4-tri-O-benzoyl-i-

pyranosyl-(16)-i- -glucopyranosyl-(16)-

2,3,4 - tri - O - benzoyl - i - - glucopyranosyl-

(16)-2,3,4-tri-O-benzoyl-i- -glucopyran-

osyl-(16)-2,3,4-tri-O-benzoyl-h- -gluco-

pyranoside (36).—2,3,4,6-Tetra-O-acetyl-b-

glucopyranosyl-(16)-2,3,4-tri-O-benzoyl-a-

-glucopyranosyl trichloroacetimidate (28) (97

mg, 0.1 mmol) and allyl b- -glucopyranosyl-

(16)-2,3,4-tri-O-benzoyl-b- -glucopyran-

osyl-(16)-2,3,4-tri-O-benzoyl-b- -glucopy-

ranosyl-(16)-2,3,4-tri-O-benzoyl-a- -gluco-

D

-glucopyran-

D

-gluco-

D

1

D

-

125–128 °C; [h]_D+11.2° (c 1.0, CHCl₃). H

NMR (CDCl₃): l 8.10–7.46 (m, 75 H, BzꢀH),

6.22 (t, 1 H, J 9.7 Hz), 6.19 (t, 1 H, J 9.8 Hz),

6.14 (t, 1 H, J 9.9 Hz), 6.07 (t, 1 H, J 9.7 Hz),

6.01 (t, 1 H, J 9.7 Hz), 5.88–5.73 (m, 6 H),

5.65–5.50 (m, 5 H), 5.40–5.08 (m, 7 H), 5.06

(d, 1 H, J 7.9 Hz), 5.02 (d, 1 H, J 7.8 Hz), 4.89

(d, 1 H, J 7.9 Hz), 4.82 (d, 1 H, J 7.8 Hz),

4.65–4.60 (m, 3 H), 4.52–4.38 (m, 5 H), 4.22–

4.05 (m, 6 H), 3.85–3.42 (m, 6 H), 2.04 (s, 3

H, CH₃CO), 2.01 (s, 3 H, CH₃CO), 2.00 (s, 3

H, CH₃CO), 1.98 (s, 3 H, CH₃CO). Anal.

Calcd for C₁₅₂H₁₃₄O₅₀: C, 66.13; H, 4.86.

Found: C, 66.19; H, 4.81.

D

pyranoside (35) (164 mg, 0.1 mmol) were dried

together under high vacuum for 2 h, then

dissolved in anhyd CH₂Cl₂(30 mL). TMSOTf

(2 mL, 0.10 equiv) was added dropwise at

−42 °C with N₂protection. The reaction mix-

ture was stirred for 3 h, at the end of which

time TLC (1:1.5 petroleum ether–EtOAc) in-

dicated that the reaction was complete. Then

the mixture was neutralized with Et₃N, and

concentrated under reduced pressure to dry-

ness. Further puriﬁcation by column chro-

matography (1:1.5 petroleum ether–EtOAc)

gave 36 (171 mg, 70%) as a colorless solid: mp

i-

ranosyl - (16) - i -

i- -glucopyranosyl-(16)-i-

osyl-(16)-h- -glucopyranoside (38).—To a

D

-Glucopyranosyl-(16)-i-

- glucopyranosyl - (16)-

-glucopyran-

D

-glucopy-

D

solution of 37 (83 mg, 30 mmol) in 90% AcOH

(1 mL) containing AcONa (29.3 mg, 0.3

mmol) was added PdCl₂(8.9 mg, 0.5 mmol),

and the mixture was stirred for 12 h, at the

end of which time TLC (2:1 petroleum ether–

EtOAc) indicated that the reaction was com-

plete. The mixture was diluted with CH₂Cl₂

(20 mL), washed with water and satd aq

NaHCO₃. The organic layer was concentrated

under reduced pressure, and the residue was

passed through a short silica-gel column with

2:1 petroleum ether–EtOAc as the eluent to

1

126–129 °C; [h]_D+5.4° (c 1.3, CHCl₃). H

NMR (CDCl₃): l 8.10–7.25 (m, 60 H, BzꢀH),

6.20 (t, 1 H, J 9.7 Hz), 6.15 (t, 1 H, J 9.8 Hz),

6.06 (t, 1 H, J 9.9 Hz), 5.90–5.70 (m, 6 H),

5.46–5.09 (m, 10 H), 5.07 (d, 1 H, J 7.9 Hz),

5.00 (d, 1 H, J 8.0 Hz), 4.90 (d, 1 H, J 7.9 Hz),

4.85 (d, 1 H, J 7.8 Hz), 4.78 (d, 1 H, J 7.8 Hz),

4.65–4.53 (m, 3 H), 4.40–3.92 (m, 12 H),

3.84–3.56 (m, 5 H), 3.44–3.40 (m, 2 H), 3.26–

3.17 (m, 1 H), 2.05 (s, 3 H, CH₃CO), 2.03 (s,

3 H, CH₃CO), 2.01 (s, 3 H, CH₃CO), 2.00 (s,

3 H, CH₃CO). Anal. Calcd for C₁₃₁H₁₂₂O₄₇: C,

64.27; H, 4.99. Found: C, 64.40; H, 4.93.

give crude 2,3,4,6-tetra-O-acetyl-b-

ranosyl-(16)-2,3,4-tri-O-benzoyl-b-

pyranosyl-(16)-2,3,4-tri-O-benzoyl-b-

glucopyranosyl-(16)-2,3,4-tri-O-benzoyl-b-

-glucopyranosyl-(16)-2,3,4-tri-O-benzoyl-

b- -glucopyranosyl-(16)-2,3,4-tri-O-ben-

zoyl- -glucopyranose, which was dissolved in

D

-glucopy-

D

-gluco-

D

-

Allyl 2,3,4,6-tetra-O-acetyl-i-

osyl-(16)-2,3,4-tri-O-benzoyl-i-

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - i -

glucopyranosyl-(16)-2,3,4-tri-O-benzoyl-i-

-glucopyranosyl-(16)-2,3,4-tri-O-benzoyl-

i- -glucopyranosyl-(16)-2,3,4-tri-O-benz-

oyl-h-

D

-glucopyran-

-gluco-

D

-

D

a satd solution of NH₃in MeOH (5 mL).

After 48 h at rt, the reaction mixture was

concentrated and the residue was puriﬁed by

chromatography on Sephadex LH-20 (MeOH)

D

-glucopyranoside (37).—To the solu-

tion of 36 (122 mg, 0.05 mmol) in Py (5 mL),

BzCl (0.1 mL, 18 mmol) was added dropwise,

1

to afford 38 (23 mg, 78%) as a syrup: H

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

19

EtOAc) indicated that the reaction was com-

plete. 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 (1.5:1 petroleum

ether–EtOAc) gave 40 (125 mg, 96%) as a

colorless solid: [h]_D+12.6° (c 1.3, CHCl₃).

¹³C HMR (CDCl₃): l 170.58, 170.22, 169.34,

169.30, (4 CH₃CO), 166.09, 166.05, 166.01,

165.90, 165.87, 165,84, 165.81, 165.68, 165.47,

165.22, 165.14, 165.03, 164.93, 164.90, 164.82,

164.77, (21 C₆H₅CO, some signals over-

lapped), 104.11, 103.76, 102.75, 102.34,

101.85, 101.29, (C-1^I–VIIIsome signals over-

lapped), 75.42, 75.40, 75.36, 75.22, 75.12,

74.89, 74.68, 74.52, 74.48, 74.29, 73.87, 73.65,

73.44, 73.38, 73.11, 72.98, 72.90, 72.85, 72.62,

72.34, 72.29, 72.19, 72.12, 72.04, 71.77, 71.34,

69.37, 68.76, (C-2,3,4,5,6^I–VIIIsome signals

overlapped); MALDI-TOF–MS Anal. Calcd

for C₂₀₆H₁₇₈O₆₆: 3707.1 [M]. Found: 3730.1

NMR (D₂O): l 4.76 (s, 1 H, H-1), 4.50–4.43

(m, 5 H), 3.97–3.70 (m, 12 H), 3.68–3.51 (m,

18 H), 3.36–3.30 (m, 6 H). Anal. Calcd for

C₁₅₂H₁₃₄O₅₀: C, 66.13; H, 4.86. Found: C,

66.17; H, 4.82.

Allyl 2,3,4,6-tetra-O-acetyl-i-

osyl-(16)-2,3,4-tri-O-benzoyl-i-

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - i -

glucopyranosyl-(16)-2,3,4-tri-O-benzoyl-i-

-glucopyranosyl-(16)-i- -glucopyranosyl-

(16)-2,3,4-tri-O-benzoyl-i- -glucopyran-

osyl-(16)-2,3,4-tri-O-benzoyl-i- -gluco-

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - h -

D

-glucopyran-

-gluco-

D

-

D

-

glucopyranoside (39).—Compound 34 (191

mg, 0.1 mmol) and 35 (164 mg, 0.1 mmol)

were dried together under high vacuum for 2

h, then dissolved in anhyd CH₂Cl₂(30 mL).

TMSOTf (1.5 mL, 0.08 equiv) was added

dropwise at −42 °C with N₂protection. The

reaction mixture was stirred for 3 h. Then the

mixture was neutralized with Et₃N, and con-

centrated under reduced pressure to an oily

residue. Puriﬁcation by column chromatogra-

phy (1:1.5 petroleum ether–EtOAc) gave 39

(210 mg, 62%) as a colorless solid: mp 123–

1

[M+Na], 3746.0 [M+K]: H NMR (CDCl₃):

l 8.08–7.25 (m, 105 H, BzꢀH), 6.30–5.60 (m,

19 H), 5.38–5.23 (m, 9 H), 4.90–3.30 (m, 33

H), 2.10 (s, 3 H, CH₃CO), 2.05 (s, 3 H,

CH₃CO), 1.98 (s, 3 H, CH₃CO), 1.88 (s, 3 H,

CH₃CO). Anal. Calcd for C₂₀₆H₁₇₈O₆₆: C,

66.70; H, 4.80. Found: C, 66.63; H, 4.83.

1

126 °C; [h]_D+9.6° (c 1.2, CHCl₃). H NMR

(CDCl₃): l 8.16–7.26 (m, 90 H, BzꢀH), 6.30

(t, 1 H, J 9.8 Hz), 6.24 (t, 1 H, J 9.8 Hz), 6.18

(t, 1 H, J 9.9 Hz), 6.15–5.75 (m, 11 H),

5.60–5.26 (m, 8 H), 5.22–5.06 (m, 6 H), 5.02

(d, 1 H, J 7.8 Hz), 4.96 (d, 1 H, J 7.7 Hz), 4.85

(d, 1 H, J 7.8 Hz), 4.75 (d, 1 H, J 7.9 Hz),

4.60–4.42 (m, 8 H), 4.36–4.04 (m, 11 H),

4.00–3.70 (m, 5 H), 3.67–3.50 (m, 5 H), 2.08

(s, 3 H, CH₃CO), 2.04 (s, 3 H, CH₃CO), 1.96

(s, 3 H, CH₃CO), 1.89 (s, 3 H, CH₃CO). Anal.

Calcd for C₁₈₅H₁₆₆O₆₃: C, 65.41; H, 4.89.

Found: C, 65.47; H, 4.83.

i-

ranosyl - (16) - i -

i- -glucopyranosyl-(16)-i-

osyl - (16) - i - - glucopyranosyl - (16) - i-

-glucopyranosyl-(16)-h- -glucopyranoside

D

-Glucopyranosyl-(16)-i-

- glucopyranosyl - (16)-

-glucopyran-

D

-glucopy-

D

(41).—To a solution of 40 (148 mg, 40 mmol)

in 90% AcOH (1 mL) containing AcONa

(29.3 mg, 0.3 mmol) was added PdCl₂(8.9 mg,

0.5 mmol), and the mixture was stirred for 12

h, at the end of which time TLC (2:1

petroleum ether–EtOAc) indicated that the

reaction was complete. The mixture was di-

luted with CH₂Cl₂(30 mL), washed with wa-

ter and satd aq NaHCO₃. The organic layer

was concentrated under reduced pressure, and

the residue was passed a short silica-gel

column with 2:1 petroleum ether–EtOAc as

the eluent to give crude 2,3,4,6-tetra-O-acetyl-

Allyl 2,3,4,6-tetra-O-acetyl-i-

osyl-(16)-2,3,4-tri-O-benzoyl-i-

pyranosyl - (16) - 2,3,4 - tri - O - benzoyl - i -

glucopyranosyl-(16)-2,3,4-tri-O-benzoyl-i-

-glucopyranosyl-(16)-2,3,4-tri-O-benzoyl-

i- -glucopyranosyl-(16)-2,3,4-tri-O-ben-

zoyl-i- -glucopyranosyl-(16)-2,3,4-tri-O-

benzoyl-i- -glucopyranosyl-(16)-2,3,4-tri-

O-benzoyl-h- -glucopyranoside (40).—To a

D

-glucopyran-

D

-gluco-

D

-

D

solution of 39 (119 mg, 0.035 mmol) in Py (5

mL), BzCl (0.1 mL, 24 mmol) was added

dropwise, and the mixture was stirred

overnight at rt. TLC (1.5:1 petroleum ether–

b-

zoyl - b -

O-benzoyl-b-

D

-glucopyranosyl-(16)-2,3,4-tri-O-ben-

- glucopyranosyl - (16) - 2,3,4 - tri-

-glucopyranosyl-(16)-2,3,4-

D

20

Y. Zhu, F. Kong / Carbohydrate Research 332 (2001) 1–21

(d) Wang, W.; Kong, F. Angew. Chem., Int. Ed. Engl.

1999, 38, 1247–1250; Angew. Chem. 1999, 111, 1330–

1334;

tri - O - benzoyl - b -

D

- glucopyranosyl - (16)-

- glucopyranosyl-

-glucopyran-

2,3,4 - tri - O - benzoyl - b -

D

(16)-2,3,4-tri-O-benzoyl-b-

osyl-(16)-2,3,4-tri-O-benzoyl-b-

D

(e) Becker, B.; Furneaux, R. H.; Reck, F.; Zubkov, O. A.

Carbohydr. Res. 1999, 315, 148–157;

(f) Kaur, K. J.; Hindsgaul, O. Glycoconjugate J. 1991, 8,

90–96;

(g) Roy, R.; Page, D.; Figueroa-Perez, S.; Verez-Ben-

como, V. Glycoconjugate J. 1998, 15, 251–258;

(h) Gan, Z.; Cao, S.; Wu, Q.; Roy, R. J. Carbohydr.

Chem. 1999, 18, 755–765;

(i) Numomura, S.; Iida, M.; Numata, M.; Sugimoto, M.;

Ogawa, T. Carbohydr. Res. 1994, 263, 148–157;

(j) Zhang, Y.-M.; Brodzky, A.; Sinay¨, P.; Saint-Marcoux,

G.; Perly, B. Tetrahedron: Asymmetry 1995, 6, 1195–

1202;

D

ose (122 mg), which was dissolved in a satd

solution of NH₃in MeOH (5 mL). After 48 h

at rt, the reaction mixture was concentrated,

and the residue was puriﬁed by chromatogra-

phy on Sephadex LH-20 (MeOH) to afford 41

1

as a syrup (40 mg, 76%): H NMR (D₂O): l

4.78 (s, 1 H, H-1), 4.52–4.41 (m, 7 H), 3.98–

3.71 (m, 16 H), 3.69–3.50 (m, 24 H), 3.39–

3.28 (m, 8 H). Anal. Calcd for C₄₈H₈₂O₄₁: C,

43.84; H, 6.24. Found: C, 43.80; H, 6.27.

(k) Jain, R. K.; Huang, B. -G.; Chandrasekaran, E. V.;

Matta, K. L. Chem. Commun. (Cambridge) 1997, 23–26;

(l) Figueroa-Perez, S.; Verez-Bencomo, V. Tetrahedron

Lett. 1998, 9143–9146.

4. (a) Ernst, B.; De Mesmaeker, A.; Wagner, B.; Winkler, T.

Tetrahedron Lett. 1990, 6167–6170;

Acknowledgements

(b) Banoub, J.; Boullanger, P.; Potier, M.; Descotes, G.

Tetrahedron Lett. 1986, 4145–4148;

(c) Dahlin, B. M.; Garegg, P. J.; Johansson, R.; Sa-

muelsson, B.; Orn, U. Acta Chem. Scand. Ser. B 1981, 35,

669–672;

This work was supported by The Chinese

Academy of Sciences (Projects KJ952J₁510

and RCEES9904) and by The National Natu-

ral Science Foundation of China (Projects

29802009, 30070185 and 39970864).

(d) Banoub, J.; Bundle, D. R. Can J. Chem. 1979, 57,

2091–2096;

(e) Ogawa, T.; Matsui, M. Carbohydr. Res. 1976, 51, C13;

(f) Zurabyan, S. E.; Tikhomirov, M. M.; Nesmeyanov, V.

A.; Khorlin, A. Y. Carbohydr. Res. 1973, 26, 117–126;

(g) Wulff, G.; Kruger, W. Carbohydr. Res. 1971, 19,

139–146;

(h) Kochetkov, N. K.; Bochkov, A. F.; Sokolovskaya, T.

A.; Snyatkova, V. J. Carbohydr. Res. 1971, 16, 17–25;

(i) Kochetkov, N. K.; Khorlin, A. J.; Bochkov, A. F.

Tetrahedron 1967, 23, 693–702.

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.

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