Toward the automated solid-phase synthesis of oligoglucosamines: Systematic evaluation of glycosyl phosphate and glycosyl trichloroacetimidate building blocks

Carbohydrate Research 337 (2002) 1893–1916

www.elsevier.com/locate/carres

Toward the automated solid-phase synthesis of oligoglucosamines:

systematic evaluation of glycosyl phosphate and glycosyl

trichloroacetimidate building blocks

Luis G. Melean, Kerry R. Love, Peter H. Seeberger*

Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Received 30 April 2002; accepted 29 July 2002

Dedicated to Professor Derek Horton on the occasion of his 70th birthday

Abstract

Glucosamines are common components of many biologically important oligosaccharides. Reported is a systematic evaluation

of glucosamine phosphates and trichloroacetimidates as glycosylating agents for the efﬁcient construction of b-(16) glucosamine

linkages. A set of differentially protected glucosamine donors incorporating a host of amine protecting groups, including

2-phthaloyl, benzyloxycarbonyl (Z), trichloroetheoxycarbonyl (Troc) and trichloroacetyl (TCA) protective groups, were prepared.

Donors were initially evaluated for reactivity and protecting group compatibility in a solution-phase study with a model

6-hydroxyl galactose acceptor. Based on these results, glucosamine donor 10 was selected for the solution-phase synthesis of a

b-(16)-glucosamine pentasaccharide. Finally, building block 10 proved well suited for use in the automated solid-phase

synthesis of a repeating unit trisaccharide. An assessment of glucosamine phosphate donors as potential glycosylating agents for

Keywords: Glucosamines; Glycosyl phosphates; Automated solid-phase synthesis

1. Introduction

tive and passive immunization with PNSG was effective

in protecting mice against metastatic kidney infection

by S. aureus, making PNSG a potential vaccine for

clinical use.⁶The isolation of PNSG from natural

sources is a difﬁcult task that yields a heterogeneous

mixture of oligosaccharides. Synthetic polyglucosamine

oligosaccharides would be important tools to determine

the minimal length required to illicit a speciﬁc immune

response and to provide the necessary substrates for

biochemical and biophysical studies.

Oligosaccharides serve to mediate a host of biological

processes including cell–cell adhesion, immune re-

sponse, and parasitic infection.^1,2Cell-surface carbohy-

drates often are highly speciﬁc for a pathogen or cell

type, and the induction of an immune response against

a unique carbohydrate antigen may allow for the cre-

ation of carbohydrate-based vaccines. Vaccines against

bacteria and cancer based on carbohydrate antigens

have spurred substantial interest in recent years.³

In Nature, 2-amino-2-deoxy glycosides are frequently

encountered in glycoproteins and glycolipids.⁴Poly-N-

succinyl-b-(16)-glucosamine (PNSG, Fig. 1), for ex-

ample, is an in vivo-expressed surface polysaccharide in

human Staphylococcus aureus infection.⁵Recently, ac-

The coupling efﬁciency and relative ease in the prepa-

ration of 2-amino-2-deoxy glycosides is signiﬁcantly

lower than for other glycosides. Ideally, the construc-

* Corresponding author. Fax: +1-617-2537929

E-mail address: seeberg@mit.edu (P.H. Seeberger).

Figure 1. Structure of PNSG. R=acetyl or succinyl.

PII: S0008-6215(02)00299-9

1894

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

tion of polyglucosamine oligosaccharides, such as

PSNG, could be simpliﬁed by rapid assembly in an

automated fashion on solid support. Automated solid-

phase oligosaccharide synthesis requires differentially

protected building blocks that allow for the efﬁcient

and selective creation of each desired linkage. In this

case, glucosamine building blocks would be added se-

quentially to a growing oligosaccharide chain, until

completion of the oligomer of desired length. Stepwise

synthesis of this kind can greatly reduce overall reac-

tion times as longer oligomers can be assembled using

the same donor created for shorter constructs. Al-

though glucosamine building blocks have been utilized

for solid-phase carbohydrate synthesis⁷and even auto-

mated synthesis,⁸the preparation of polyglucosamine

sequences on solid support has not been reported to

date. Here we report a systematic evaluation of differ-

entially protected glycosyl phosphate and glycosyl

trichloroacetimidate monosaccharide building blocks

for the synthesis of oligosaccharides in solution, and by

automated solid-phase synthesis.

Two anomeric leaving groups were evaluated as they

had successfully been used in previous solid-phase

oligosaccharide syntheses: glycosyl trichloroacetimi-

dates and glycosyl phosphates. Glycosyl trichloroace-

timidates historically have served well in the formation

of a host of glycosidic linkages in solution and on solid

support.¹¹More recently, glycosyl phosphates have

proven useful building blocks in the preparation of a

variety of glycosidic linkages in solution¹²and for

solid-phase oligosaccharide assembly.^8,13Several differ-

entially protected glucosamine trichloroacetimidates

and glucosamine phosphates were prepared using stan-

dard protecting group manipulations. These glu-

cosamine building blocks were initially screened for

their performance in couplings with 1,2:3,4-di-O-iso-

propylidene-D-galctose (1) as a model acceptor (Table

1).

The construction of 2-amino-2-deoxy b-glycosides

typically relies on a 2-phthalimido group for the amino-

protecting and C-2 participating group.¹⁰Conse-

quently, our initial investigations focused on the

synthesis and use of 2-phthalimido-containing donors.

The 6-hydroxyl temporary protecting group was then

chosen for orthogonality with the amino protecting

group, since removal must be effected without the use

of strong base. 6-O-Triisopropylsilyl (TIPS) protected

glucosamine trichloroacetimidate 2 performed well in

the solution coupling with 1 to fashion disaccharide 3

in 70% yield, but removal of the silyl ether proved too

slow to be useful in automated synthesis. Installation of

an acid-labile p-methoxybenzyl PMB ether to mask the

6-hydroxyl group (donor 4) was not useful; exposure to

catalytic TMSOTf for donor activation resulted in a

loss of the PMB ether. Protection using the recently

developed 2-(azidomethyl)benzoate (AZMB)¹⁴or levuli-

nate esters, which are both removed under neutral

conditions via assisted cleavage reactions, proved suc-

cessful and allowed for the use of acetate esters as

permanent protecting groups on the 3- and 4-hydroxyl

groups. Coupling of glucosamine imidate donors 6 and

8 with acceptor 1 procured the corresponding disaccha-

rides 7 and 9 in similar yields.

While glycosyl phosphates have proven to be excel-

lent glycosylating agents for the installation of a variety

of glycosidic linkages,^12,15no systematic study of differ-

entially protected glycosyl phosphates for the formation

of b-glucosamine glycosidic linkages had been under-

taken. In order to address this challenge and to com-

pare glycosyl phosphates to the corresponding glycosyl

trichloracetimidate building blocks, we prepared glu-

cosamine phosphate donors 10 and 12. Based on previ-

ous experiments, a 6-O-levulinoyl group was selected

for temporary protection and acetate and benzyl ether

groups were employed as permanent protecting groups

for evaluation the electronic effects of the protective

groups on donor reactivity. Coupling of glycosyl phos-

2. Results and discussion

Glucosamine building blocks for the assembly of

linear b-(16)-glucosamine antigens containing acetyl-

ated and succinylated amino groups must be equipped

with: (a) two orthogonal, participating amine protect-

ing groups to ensure the formation of trans b-(16)

linkages; (b) a temporary protecting group for the

6-hydroxyl group that is stable to the glycosylation

reactions but can be readily removed under mild condi-

tions; and (c) stable, permanent protecting groups for

the 3- and 4-hydroxyl groups to be removed only at the

end of the synthesis.

In addition to these considerations, we were mindful

that different protecting groups have a fundamental

impact on the reactivity of glucosamine building blocks

both as glycosylating agents and as glycosyl accep-

tors.^9,10Fine-tuning the glucosamine building blocks to

fulﬁll these requirements necessitated a systematic eval-

uation of glucosamine monosaccharides containing dif-

ferent anomeric leaving groups, as well as various

combinations of hydroxyl and amine protecting groups

(Fig. 2).

Figure 2. Glucosamine phosphate building block design con-

siderations.

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

1895

Table 1

Summary of the glycosylation experiments involving different glucosamine building blocks

Glucosamine

R¹

R²

R³

R⁴

Disaccharide

Coupling yield (%)

2

4

6

8

10

12

14

16

18

20

22

24

26

C(NH)CCl₃

PO(OBu)₂

C(NH)CCl₃

PO(OBu)₂

C(NH)CCl₃

PO(OBu)₂

Phth

Z

TIPS

PMB

AZMB

Lev

Ac

Lev

Ac

Bn

Ac

Bn

Ac

Bn

Ac

Bn

Ac

Bn

Ac

Bn

3

5

7

70

decompos.

68

65

85

83

88

90

91

81

87

88

50

9

11

13

15

17

19

21

23

25

27

Troc

TCA

Lev

phate donors 10 and 12 with galactose 1 furnished the

desired disaccharides 11 and 13 in good yields of 85 and

83%, respectively.

furnished disaccharide 33 (Scheme 1). Glycosylation

with donor 10 and subsequent deprotection of the

6-hydroxyl was repeated an additional 3 times to com-

plete pentasaccharide 36 in a 33% overall yield. Solu-

tion phase studies indicated that coupling yields for the

formation of b-(16) linkages are lower than those

obtained for other glucosamine couplings.⁸

Based on our solution-phase results, the automated

synthesis of polyglucosamine oligosaccharides was in-

vestigated. Octenediol-functionalized resin 37¹⁸was

used as the initial acceptor in the automated assembly

of trisaccharide 34 (Scheme 2). Each monomer unit was

incorporated via a coupling cycle employing ﬁve equiv-

alents of donor 10 for each glycosylation step. Building

block 10 was delivered to the reaction vessel and acti-

vated by stoichiometric TMSOTf at −15 °C. Each

The limitations imposed by base lability of the ph-

thalimido group for amine protection prompted us to

study the use of other, more base-stable participating

protecting groups. Benzyloxycarbonyl (Z) protected

glucosamine trichloroacetimidates (14, 16) and phos-

phates (18, 20) resulted in acceptable coupling yields

regardless of the protecting group pattern selected.

Trichloroethoxycarbonyl (Troc) protected trichloroace-

timidate 22 also yielded high levels of desired disaccha-

ride 23. Finally, N-trichloroacetate-protected gluco-

samine trichloroacetimidate 24 outperformed phos-

phate 26 due to electronically favorable oxazoline for-

mation in the case of electron-rich donor 26.¹⁶

Additionally, we wanted to demonstrate the scope of

glycosylations involving glucosamine phosphate build-

ing blocks. Phosphate 10 was successfully reacted with

the 3-hydroxyl group of galactopyranoside 28 and the

4-hydroxyl group of glucopyranoside 30 to afford dis-

accharides 29 and 31 (Table 2).

Table 2

Scope of glycosylation reactions involving glucosamine glyco-

syl phosphates

Encouraged by the performance of differentially pro-

tected glucosamine phosphates in the formation of dis-

accharides, we conducted the solution-phase assembly

of pentaglucoside 36. Glycosyl phosphate 10 proved to

be the highest yielding donor amenable to conditions

for automated solid-phase synthesis. Coupling of glyco-

syl phosphate 10 with n-pentenyl glucosamine 32, fol-

lowed by removal of the 6-O levulinate group with

hydrazine monohydrate¹⁷in a pyridine–AcOH solution

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L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

disaccharide 31 (9%) resulting from incomplete glycosy-

lation and deprotection steps (Schemes 3–14.

3. Conclusions

Glucosamine trichloroacetimidate and phosphate

donors were evaluated for the construction of b-(16)-

polyglucosamines. Glucosamine phosphates also

demonstrated usefulness in glycosylation of other posi-

tions; both the 3-hydroxyl of a galactose acceptor and

the 4-hydroxyl of a glucose acceptor were glycosylated

in high yield. Phosphate donor 10 was selected for use

in the solution-phase synthesis of a repeating unit pen-

tasaccharide based on a good coupling yield with model

acceptor 1 and possession of a protecting group scheme

amenable to future automation. Protected pentasaccha-

ride 36 was subsequently synthesized in a 33% overall

yield. This solution-phase synthesis served as the basis

for an automated solid-phase synthesis of a repeating

unit trisaccharide. Again, phosphate 10 was used in a

series of three coupling–deprotection cycles to afford

trisaccharide 34 in a 17% yield in nine hours.

Scheme 1. Synthesis of pentasaccharide 36 in solution using

phosphate donor 10. (a) 10, TMSOTf, CH₂Cl₂, −20 °C; (b)

hydrazine, AcOH, Pyr.

4. Experimental

General methods.—All chemicals were reagent grade

and used as supplied unless otherwise noted.

Dichloromethane (CH₂C1₂), tetrahydrofuran (THF),

and toluene were puriﬁed and supplied in a J.T. Baker

Cycle Tainer Solvent Delivery System. Pyridine, aceto-

nitrile and triethylamine were reﬂuxed over calcium

hydride and distilled prior to use. Analytical thin-layer

chromatography was performed on E. Merck Silica Gel

60 F₂₅₄plates (0.25 mm). Compounds were visualized

by dipping the plates in cerium sulfate–ammonium

molybdate solution, followed by heating. Liquid

column chromatography was performed using forced

ﬂow of the indicated solvent on Silicycle silica 230–400

Scheme 2. Automated synthesis of trisaccharide 34 using

phosphate donor 10. (a) TMSOTf, CH₂C1₂, −15 °C; (b)

NH₂NH₂, AcOH, pyr; (c) Grubbs’ catalyst, ethylene,

CH₂C1₂.

mesh (60 A pore diameter). ¹H NMR spectra were

,

obtained using a Bruker 400 spectrometer (400 MHz)

or a Varian VXR-500 (500 MHz) spectrometer and are

reported in parts per million (l) relative to CDCl₃(7.27

ppm) or CD₃OD (4.84 ppm). Coupling constants (J)

are reported in Hertz. ¹³C NMR spectra were obtained

using a Bruker 400 NMR spectrometer (100 MHz) or a

Varian VXR-500 (125 MHz) and are reported in l

relative to CDCl₃(77.23 ppm) or CD₃OD (49.15 ppm).

³¹P spectra were obtained using a Varian VXR-300 (120

MHz) or a Varian-300 (200 MHz) instrument and are

reported in l relative to H₃PO₄(0.00 ppm) as an

external reference. IR spectra were obtained on a

Perkin–Elmer 1600 series FTIR spectrometer. Optical

rotations were recorded on a Perkin–Elmer 241 polar-

imeter using a sodium lamp (589 mm). MALDI-TOF

mass spectrometry was performed on a PE Biosystems

30-minute glycosylation sequence was followed by ex-

tensive washing of the resin before removal of the

levunilate esters was carried out as a double deprotec-

tion at ambient temperature with a solution of hydra-

zine monohydrate (0.5 M) in pyridine–AcOH (Table

3). Iteration of glycosylation and deprotection steps for

incorporation of each monomer unit resulted in com-

pletion of the trisaccharide in 9 h. After completion of

the synthesis, cleavage of the resin-bound products

using Grubbs’ catalyst under an atmosphere of ethylene

afforded the fully protected trisaccharide 34 in 17%

yield (74% per step over six reactions), along with

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

1897

Table 3

Automated cycle for glycosylation and deprotection used with glucosamine phosphate donors

Step

Function

Reagent

Time (min)

1

2

3

4

5

6

7

8

9

Couple

Wash

Couple

Wash

Deprotection

Wash

5 equiv donor and 5 equiv TMSOTf

Dichloromethane

5 equiv donor and 5 equiv TMSOTf

Dichloromethane

30

10

30

10

80

10

Tetrahydrofuran

2×20 equiv hydrazine (3:2 pyridine–acetic acid)

0.2 M acetic acid in tetrahydrofuran

Tetrahydrofuran

Wash

Dichloromethane

Voyager System 102 on a 2,5-dihydrobenzoic acid ma-

trix. HPLC analysis was performed on a Waters Model

600E Multisolvent Delivery System.

(100 mL). The aqueous layer was extracted with ether

(3×100 mL), and the combined organic phases were

washed with brine, dried over Na₂SO₄, ﬁltered, and

n-Pentenyl 3,4-di-O-benzyl-2-deoxy-2-phthalimido-6-

O-triisopropylsilyl-i-^D-glucopyranoside (B).—To

a

stirred solution of n-pentenyl glycoside A (2.84 g, 7.82

mmol) in dry DMF (80 mL) at 0 °C was added imida-

zole (0.55 g, 8.06 mmol) and triisoprophylchlorosilane

(1.66 g, 8.06 mmol). The solution was slowly warmed to

ambient temperature and stirred for 14 h. Water (100

mL) was added, the aqueous layer was extracted with

ether (3×100 mL), and the combined organic phases

were washed with brine and dried over Na₂SO₄. After

ﬁltration and concentration in vacuo, the crude product

was puriﬁed by ﬂash silica gel chromatography (4:6

EtOAc–hexanes) to afford 3.56 g (86%) of n-pentenyl

2-deoxy-2-phthalimide-6-O-triisopropylsilane-b-^D-

Scheme 3. Synthesis of trichloroacetimidate donors 2 and 4.

glucopyranoside as a white solid. [h]_D−35.2° (c 1.01,

CH₂Cl₂); IR (thin ﬁlm): 3447, 1776, 1716, 1392, 1069

1

cm⁻¹; H NMR (400 MHz, CDCl₃) l 7.86–7.75 (m,

2H), 7.74–7.64 (m, 2H), 5.63–5.49 (m, 1H), 5.18 (d, J

8.4 Hz, 1H), 4.79–4.65 (m, 2H), 4.39–4.28 (m, 1H) 4.09

(dd, J 4.9, 10.0 Hz, 1H), 4.00–3.92 (m, 2H), 3.77 (td, J

6.3, 9.7 Hz, 1H), 3.66–3.58 (m, 1H), 3.58–3.44 (m, 1H),

3.40 (td, J 6.8, 9.7 Hz, 1H), 3.27–3.20 (m, 1H), 1.91–

1.77 (m, 2H), 1.58–1.36 (m, 2H), 1.22–0.91 (m, 21H);

¹³C NMR (100 MHz, CDCl₃) l 168.5, 137.9, 134.2,

131.8, 123.5, 114.8, 98.3, 75.6, 73.8, 71.7, 68.9, 65.8,

56.3, 30.0, 28.6, 17.5, 12.3; ESI FT-MS: m/z (m+Na)⁺

calcd 556.2707, obsd 556.2693.

n-Pentenyl 2-deoxy-2-phthalimido-6-O-triisopropyl-

silane-b-^D-glucopyranoside (4.32 g, 8.15 mmol) was

azeotroped with toluene (3×10 mL), dried under vac-

uum for 1 h, dissolved in DMF (40 mL), and cooled to

0 °C. Benzyl bromide (3.34 g, 19.6 mmol) was passed

through basic aluminum oxide and added to the reac-

tion mixture. After 30 min, sodium hydride (782 mg,

19.6 mmol, 60% dispersion in mineral oil) was added to

the reaction mixture in 4 batches over a period of 1 h.

The solution was stirred for 12 h at ambient tempera-

ture, then quenched by the dropwise addition of water

Scheme 4. Synthesis of glucosamine donors 6.

Scheme 5. Synthesis of trichloroacetimidate 8.

Scheme 6. Synthesis of glucosamine phosphate donor 10.

Scheme 7. Synthesis of glucosamine phosphate donor 12.

1898

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

2H), 3.83 (dd, J 9.2, 9.5 Hz, 1H), 3.74 (td, J 6.4, 9.8 Hz,

1H), 3.52–3.46 (m, 1H), 3.38 (td, J 7.3, 9.7 Hz, 1H),

1.88–1.78 (m, 2H), 1.55–1.41 (m, 2H), 1.23–0.94 (m,

21H); ¹³C NMR (125 MHz, CDC1₃) l 138.5, 138.3,

138.2, 133.9, 128.7, 128.6, 128.2, 128.1, 128.9, 127.5,

123.5, 123.3, 114.7, 98.0, 79.6, 79.4, 76.2, 75.2, 75.0,

68.4, 62.5, 56.2, 30.1, 28.7, 18.2, 12.2; ESI FT-MS: m/z

(M+Na)⁺calcd 736.3645, obsd 736.3617.

Scheme 8. Synthesis of trichloroacetimidate donor 14.

3,4-Di-O-benzyl-2-deoxy-2-phthalimido-6-O-triiso-

propylsilyl-i-D-glucopyranosyl

trichloroacetimidate

(2).—To a stirred solution of B (411 mg, 0.57 mmol) in

CH₃CN (5 mL) and H₂O (0.50 mL) was added NBS

(307 mg, 1.73 mmol). The reaction mixture was

shielded from light and stirred, diluted with ether (50

mL), and extracted with satd Na₂S₂O₃(5×10 mL). The

aqueous layer was extracted with ether (50 mL), and

the combined organic phases were washed with brine

and dried over Na₂SO₄. After ﬁltration and concentra-

tion in vacuo, the crude product was azeotroped with

toluene (3×3 mL), dried under vacuum for 1 h, and

dissolved in CH₂C1₂(2.0 mL). After cooling to 0 °C,

trichloroacetonitrile (0.68 g, 4.69 mmol) and DBU (14.0

mg, 94.0 mmol) were added, and the reaction mixture

was stirred for 2 h. The solution was concentrated in

vacuo and puriﬁed by ﬂash silica gel chromatography

(3:7 EtOAc–hexanes) to afford 233 mg (51%) of 2 as a

clear oil. [h]_D+55.1° (c 0.87, CH₂Cl₂); IR (thin ﬁlm):

Scheme 9. Synthesis of glucosamine donor 16.

Scheme 10. Synthesis of glucosamine phosphate 18.

1779, 1717, 1387, 1054, 2942 cm^{−1 1}H NMR (400

;

MHz, CDCl₃) l 8.38 (d, J 4.6 Hz, 1H), 7.78–7.45 (m,

4H), 7.38–7.19 (m, 5H), 6.98–6.89 (m, 2H), 6.85–6.68

(m, 3H), 6.36 (d, J 8.6 Hz, 1H), 4.81 (d, J 4.1 Hz, 2H),

4.70 (d, J 12.3 Hz, 1H), 4.40 (d, J 11.7 Hz, 1H), 4.38 (d,

J 10.6 Hz, 1H), 4.31 (dd, J 8.6, 10.7 Hz, 1H), 4.04–3.97

(m, 2H), 3.92 (dd, J 8.9, 9.4 Hz, 1H), 3.58 (d, J 9.7 Hz,

1H), 1.15–0.84 (m, 21H); ¹³C NMR (100 MHz, CDCl₃)

l 167.8, 138.4, 138.1, 134.0, 131.6, 128.8, 128.7, 128.2,

128.1, 128.0, 127.5, 123.4, 93.8, 90.7, 78.7, 77.4, 76.7,

75.2, 75.1, 61.9, 55.2, 18.1, 12.1; ESI FT-MS: m/z

(M+Na)⁺calcd 811.2115, obsd 811.2147.

Scheme 11. Synthesis of glucosamine phosphate 20.

Scheme 12. Synthesis of glucosamine trichloroacetimidate

donor 22.

n-Pentenyl

3,4-di-O-benzyl-2-deoxy-6-O-(4%-meth-

oxybenzyl)-2-phthalimido-i-D-glucopyranoside (C).—

To a stirred solution of B (0.97 g, 1.36 mmol) in THF

(20 mL) was added AcOH (61 mL, 1.02 mmol) and

TBAF (2 mL, 2 mmol, 1 M in THF). After 12 h, the

reaction was quenched by the addition of satd NaHCO₃

(50 mL), and the aqueous layer was extracted with

ether (3×100 mL). The combined organic phases were

washed with brine, dried over Na₂SO₄, ﬁltered, and

concentrated in vacuo. Puriﬁcation by ﬂash silica gel

chromatography (3:7 EtOAc–hexanes) afforded 570 mg

(73%) of n-pentenyl 3,4-di-O-benzyl-2-deoxy-2-phthal-

Scheme 13. Synthesis of trichloroacetimidate donor 24.

concentrated in vacuo. Puriﬁcation by ﬂash silica gel

chromatography (2:8 EtOAc–hexanes), afforded 4.17 g

(72%) of B as a clear oil. [h]_D+17.5° (c 1.06, CH₂C1₂);

1

IR (thin ﬁlm): 1777, 1715, 1388, 1071 cm⁻¹; H NMR

(500 MHz, CDC1₃) l 7.84–7.60 (m, 4H), 7.40–7.24 (m,

5H), 7.04–7.00 (m, 2H), 6.93–6.82 (m, 3H), 5.64–5.54

(m, 1H), 5.12 (d, J 8.5 Hz, 1H), 4.89 (d, J 11.0 Hz, 1H),

4.84–4.80 (m, 2H), 4.79–4.69 (m, 2H), 4.48 (d, J 12.2

Hz, 1H), 4.35 (dd, J 8.9, 10.7 Hz, 1H), 4.06–3.98 (m,

imido-b-^D-glucopyranoside as

a white solid. [h]_D

+27.5° (c 0.56, CH₂C1₂); IR (thin ﬁlm): 3475, 1775,

1713, 1390, 1076 cm⁻¹; ¹H NMR (500 MHz, CDC1₃) l

7.85–7.57 (m, 4H), 7.40–7.28 (m, 5H), 7.04–6.92 (m,

2H), 6.92–6.83 (m, 3H), 5.59–5.50 (m, 1H), 5.17 (d, J

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

1899

77.4, 75.1, 74.9, 73.3, 68.9, 68.3, 56.1, 55.4, 29.9, 28.6;

ESI FT-MS: m/z (M+Na)⁺calcd 700.2886, obsd

(M−(n-pentenyl)+Na)⁺632.2224.

8.5 Hz, 1H), 4.90 (d, J 11.0 Hz, 1H), 4.82 (d, J 11.9 Hz,

1H), 4.76–4.73 (m, 2H), 4.70 (dd, J 8.5, 10.7 Hz, 1H),

4.13 (dd, J 8.2, 10.7 Hz, 1H) 3.94 (ddd, J 2.8, 4.5, 11.9

Hz, 1H), 3.82–3.71 (m, 3H), 3.56 (ddd, J 2.4, 4.3, 9.8

Hz, 1H), 3.39 (ddd, J 6.4, 7.0, 13.4 Hz, 1H), 1.96 (dd,

J 5.5, 7.9 Hz, 1H), 1.89–1.75 (m, 2H), 1.56–1.39 (m,

2H); ¹³C NMR (125 MHz, CDC1₃) l 138.1, 138.0,

137.8, 133.9, 128.7, 128.6, 128.3, 128.2, 128.1, 128.0,

127.5, 123.5, 114.8, 98.4, 79.5, 79.2, 77.43, 75.3, 75.2,

74.9, 69.1, 61.9, 56.1, 29.9, 28.6; ESI FT-MS: m/z

(M+Na)⁺calcd 580.2311, obsd 580.2316.

3,4-Di-O-benzyl-2-deoxy-6-O-(4%-methoxybenzyl)-2-

phthalimido-i-^D-glucopyranosyl

trichloroacetimidate

(4).—To a stirred solution of C (572 mg, 0.94 mmo1)

in CH₃CN (2 mL) and H₂O (0.25 mL) was added NBS

(502 mg, 2.82 mmol). After stirring for 14 h shielded

from light, the solution was diluted with ether (10 mL)

and extracted with satd Na₂S₂O₃(5×10 mL). The

aqueous layer was extracted with ether (100 mL), and

the combined organic phases were washed with brine

and dried over Na₂SO₄, ﬁltered and concentrated in

vacuo. The crude product was azeotroped with toluene

(3×3 mL), dried under vacuum for 2 h, and dissolved

in CH₂Cl₂(2 mL). After cooling to 0 °C, trichloroace-

tonitrile (0.714 g, 4.97 mmol) and DBU (43 mg, 0.28

mmol) were added, and the reaction mixture was stirred

for 2 h. The solution was concentrated in vacuo, and

the crude product was puriﬁed by ﬂash silica gel chro-

matography (3:7 EtOAc–hexanes) to afford 388 mg

(55%) of 4 as a clear oil. [h]_D+66.0° (c 1.04, CH₂Cl₂);

n-Pentenyl 3,4-di-O-benzyl-2-deoxy-2-phthalimido-b-

D-glucopyranoside (5.32 g, 9.55 mmol) was azeotroped

with toluene (3×10 mL), dried under vacuum for 1 h,

and dissolved in DMF (30 mL). The solution was

cooled to 0 °C, sodium hydride (476 mg, 12.4 mmol,

60% dispersion in mineral oil) was added, and the

reaction mixture was stirred for 1 h. After addition of

PMB-Cl (2.23 g, 14.3 mmol), the solution was warmed

to 80 °C and stirred for 14 h. The reaction was cooled

to ambient temperature and quenched by the dropwise

addition of H₂O (100 mL). The aqueous layer was

extracted with ether (3×100 mL), and the combined

organic phases were washed with brine and dried over

Na₂SO₄, ﬁltered and concentrated in vacuo. Puriﬁca-

tion by ﬂash silica gel chromatography (2:8 EtOA–hex-

anes) afforded 4.85 g (76%) of C as a clear oil. [h]_D

+83.5° (c 1.00, CH₂C1₂); IR (thin ﬁlm): 1777, 1716,

1

IR (thin ﬁlm): 3446, 1773, 1712, 1389, 1050 cm⁻¹; H

NMR (500 MHz, CDC1₃) l 8.55 (s, 1H), 7.75–7.62 (m,

4H), 7.38–7.26 (m, 5H), 7.24–7.18 (m, 2H), 7.05–6.92

(m, 2H), 6.92–6.82 (m, 5H), 6.44–6.39 (m, 1H), 4.84

(d, J 10.7 Hz, 1H), 4.81 (d, J 12.2 Hz, 1H), 4.66 (d, J

11.9 Hz, 1H), 4.63 (d, J 0.7 Hz, 1H), 4.52 (d, J 11.9 Hz,

1H), 4.50–4.42 (m, 2H), 3.96–3.88 (m, 1H), 3.86–3.80

(m, 1H), 3.79 (s, 3H); ¹³C NMR (125 MHz, CDC1₃) l

161.0, 159.4, 138.1, 134.0, 131.6, 130.2, 129.9, 128.6,

128.3, 128.1, 128.0, 127.6, 123.5, 114.0, 94.3, 90.6, 79.2,

79.1, 76.2, 75.2, 75.0, 73.3, 67.8, 55.4, 55.0; ESI FT-MS:

m/z (M+Na)⁺calcd 775.1356, obsd 775.1348.

n-Pentenyl 3,4-di-O-acetyl-2-deoxy-2-phthalimido-i-

D-glucopyranoside (D).—To a stirred solution of B

(2.60 g, 4.88 mmol) in CH₂Cl₂(30 mL) and pyridine (10

mL) was added DMAP (120 mg, 0.98 mmol) and Ac₂O

(1.49 g, 14.6 mmol). After 2 h, the solution was diluted

with CH₂Cl₂(70 mL) and washed with HCl (10% aq

solution, 3×100 mL), H₂O (1×100 mL), brine (1×50

mL), dried over Na₂SO₄, ﬁltered, and concentrated in

1387, 1056 cm⁻^{1 1}H NMR (500 MHz, CDC1₃) l

;

7.85–7.58 (m, 4H), 7.37–7.25 (m, 4H), 7.23–7.19 (m,

2H), 7.04–6.99 (m, 2H), 6.93–6.83 (m, 3H), 5.62–5.51

(m, 1H), 5.12 (d, J 8.5 Hz, 1H), 4.83 (d, J 11.0 Hz, 1H),

4.80 (d, J 13.1 Hz, 1H), 4.76–4.68 (m, 2H), 4.64 (d, J

11.9 Hz, 1H), 4.60 (d, J 11.0 Hz, 1H), 4.52 (d, J 11.9

Hz, 1H), 4.45 (d, J 11.9 Hz, 1H), 4.34 (dd, J 8.5, 10.7

Hz, 1H), 4.18 (dd, J 8.5, 10.7 Hz, 1H), 3.80 (s, 3H),

3.78–3.72 (m, 2H), 3.64 (td, J 3.7, 9.8 Hz, 1H), 3.39 (td,

J 6.1, 9.8 Hz, 1H), 1.90–1.78 (m, 2H), 1.56–1.40 (m,

2H); ¹³C NMR (125 MHz, CDC1₃) l 163.8, 159.4,

138.1, 137.9, 133.9, 130.3, 129.8, 128.6, 128.2, 128.1,

128.0, 127.9, 127.5, 123.4, 114.8, 113.9, 98.4, 79.4, 79.4,

Scheme 14. Synthesis of phosphate donor 26.

1900

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

vacuo. Puriﬁcation by ﬂash silica gel chromatography

(2:3 EtOAc–hexanes) yielded 3.04 g (97%) of n-pen-

tenyl 3,4-di-O-acetyl-2-deoxy-2-phthalimido-6-O-triiso-

propylsilyl-b-^D-glucopyranoside as a white solid. [h]_D

+30.6° (c 1.02, CH₂C1₂); IR (thin ﬁlm): 1752, 1719,

1387, 1235, 1041 cm⁻¹; ¹H NMR (400 MHz, CDC1₃) l

7.89–7.80 (m, 2H), 7.77–7.69 (m, 2H), 5.78 (dd, J 9.1,

10.7 Hz, 1H), 5.67–5.51 (m, 1H), 5.32 (d, J 8.5 Hz,

1H), 5.12 (dd, J 9.2, 9.9 Hz, 1H), 4.80–4.69 (m, 2H),

4.27 (dd, J 8.5, 10.7 Hz, 1H), 3.86–3.82 (m, 2H), 3.79

(td, J 6.3, 9.7 Hz, 1H), 3.70 (td, J 3.5, 10.1 Hz, 1H),

3.44 (td, J 6.7, 9.7 Hz, 1H), 2.01 (s, 3H), 1.86 (s, 3H),

1.87–1.83 (m, 2H), 1.59–1.42 (m, 2H), 1.14–1.01 (m,

21H); ¹³C NMR (125 MHz, CDC1₃) l 170.6, 169.6,

137.9, 134.6, 131.6, 123.9, 114.9, 98.0, 77.4, 75.1, 71.4,

69.8, 69.0, 62.9, 54.0, 30.1, 28.7, 20.9, 20.7, 18.1, 11.9;

ESI FT-MS: m/z (M+Na)⁺calcd 640.2918, obsd

640.2904.

1777, 1746, 1717, 1388 cm⁻^{1 1}H NMR (400 MHz,

;

CDCl₃) l 7.93 (dd, J 1.2, 7.9 Hz, 1H), 7.91–7.84 (m,

2H), 7.80–7.71 (m, 2H), 7.62–7.55 (m, 1H), 7.49 (d, J

7.0 Hz, 1H), 7.45–7.30 (m, 1H), 5.99 (dd, J 9.2, 10.7

Hz, 1H), 5.68–5.54 (m, 1H), 5.44 (d, J 8.4 Hz, 2H),

4.86–4.72 (m, 3H), 4.68 (d, J 14.4 Hz, 1H), 4.40 (dd, J

8.6, 10.5 Hz, 1H), 4.38 (dd, J 4.6, 7.8 Hz, 1H), 4.24 (dd,

J 2.6, 12.2 Hz, 1H), 4.01 (ddd, J 2.7, 4.5, 10.1 Hz, 1H),

3.87 (td, J 6.2, 9.7 Hz, 1H), 3.50 (td, J 6.8, 9.7 Hz, 1H),

2.09 (s, 3H), 1.97–1.85 (m, 2H), 1.82 (s, 3H), 1.67–1.46

(m, 2H); ¹³C NMR (125 MHz, CDCl₃) l 170.9, 170.4,

165.2, 138.0, 137.8, 134.6, 133.5, 131.3, 130.2, 128.6,

128.2, 127.8, 123.8, 115.0, 98.4, 72.1, 70.8, 69.9, 69.6,

62.4, 54.9, 53.1, 30.0, 28.6, 21.0, 20.6; ESI FT-MS: m/z

(M+Na)⁺calcd 643.2110, obsd 643.2014.

To a stirred solution of n-pentenyl 3,4-di-O-acetyl-6-

O-(2%-(azidomethyl)benzoyl)-2-deoxy-2-phthalimido-b-

D-glucopyranoside (2.05 g, 3.31 mmol) in CH₃CN (30

mL) and H₂O (0.3 mL) was added NBS (1.17 g, 6.62

mmol). After 14 h shielded from light, the reaction was

diluted with ether (50 mL) and washed with satd

Na₂S₂O₃(5×50 mL). The aqueous layers were com-

bined and extracted with ether (50 mL), and the com-

bined organic layers were washed with brine and dried

over Na₂SO₄, ﬁltered and concentrated in vacuo. The

crude product was azeotroped with toluene (3×10

mL), dried under vacuum for 1 h, and dissolved in

CH₂Cl₂(20 mL). After cooling to 0 °C, trichloroace-

tonitrile (5.08 g, 35.0 mmol) and DBU (107 mg, 0.71

mmol) were added, and the reaction mixture was stirred

for 2 h. The solution was concentrated in vacuo and

puriﬁed by ﬂash silica gel chromatography (2:3

EtOAc–hexanes) to yield 1.23 g (52%, a:b=1:10) of 6

as a yellow solid. IR (thin ﬁlm): 3322, 2104, 1780, 1721,

To a stirred solution of n-pentenyl 3,4-di-O-acetyl-2-

deoxy-2-phthalimido-6-O-triisopropylsilyl-b-^D-glucopy-

ranoside (3.00 g, 4.86 mmol) in THF (50 mL) was

added AcOH (128 mL, 2.14 mmol) and TBAF (4.9 mL,

4.9 mmol, 1 M in THF). After 12 h, satd NaHCO₃(50

mL) was added, and the aqueous layer was extracted

with ether (3×100 mL). The combined organic phases

were washed with brine, dried over Na₂SO₄, ﬁltered,

and concentrated in vacuo. Puriﬁcation by ﬂash silica

gel chromatography (40% EtOAc/hexanes) afforded

1.93 g (86%) of D as a white solid. [h]_D−12.8° (c 0.98,

CH₂C1₂); IR (thin ﬁlm): 3479, 1777, 1716, 1388, 1230

1

cm⁻¹; H NMR (400 MHz, CDC1₃) l 7.91–7.82 (m,

2H), 7.79–7.70 (m, 2H), 5.65 (dd, J 8.7, 10.8 Hz, 1H),

5.62–5.51 (m, 1H), 5.35 (d, J 8.5 Hz, 1H), 4.79–4.67

(m, 2H), 4.52 (dd, J 7.9, 12.1 Hz, 1H), 4.38 (dd, J 2.0,

12.1 Hz, 1H), 4.22 (dd, J 8.5, 10.8 Hz, 1H), 3.88–3.79

(m, 1H), 3.74 (ddd, J 2.2, 4.2, 9.9 Hz, 1H), 3.71–3.62

(m, 1H), 3.50–3.40 (m, 1H), 3.22 (d, J 5.2 Hz, 1H), 2.19

(s, 3H), 1.92 (s, 3H), 1.91–1.78 (m, 2H), 1.64–1.43 (m,

2H); ¹³C NMR (100 MHz, CDCl₃) l 171.9, 171.5,

137.8, 134.5, 131.6, 114.9, 98.3, 77.4, 74.2, 73.4, 69.8,

69.4, 54.8, 29.9, 28.6, 21.1, 20.7; ESI FT-MS: m/z

(M+Na)⁺calcd, 484.1583, obsd 484.1559.

3,4-Di-O-acetyl- 6-O-(2%-(azidomethyl)benzoyl)-2-

deoxy-2-phthalimido-h,i-D-glucopyranosyl trichoroacet-

imidate (6).—To a stirred solution of D (1.70 g, 3.68

mmol) in dry CH₂Cl₂(40 mL) was added DMAP (494

mg, 4.05 mmol) and 2-(azidomethyl)benzoyl chloride

(0.79 g, 4.05 mmol). After 5 min, the reaction mixture

was diluted with CH₂Cl₂(60 mL), washed with satd

NaHCO₃, H₂O, and brine. The organic layer was dried

over Na₂SO₄, ﬁltered, and concentrated in vacuo.

Puriﬁcation by ﬂash silica gel chromatography (3:7

EtOAc–hexanes) yielded 2.11 g (93%) of n-pentenyl

3,4-di-O-acetyl-6-O-(2%-(azidomethyl)benzoyl)-2-deoxy-

2-phthalimido-(b-^D-glucopyranoside as a yellow solid.

[h]_D−5.96° (c 0.13, CH₂Cl₂); IR (thin ﬁlm): 2103,

1

1386 cm⁻¹; H NMR (400 MHz, CDCl₃) l 8.70 (s,

1H), 8.64 (s, 0.1H), 8.09 (dd, J 1.1, 7.8 Hz, 0.1H), 7.94

(dd, J 1.1, 7.8 Hz, 1H), 7.89–7.82 (m, 2.2H), 7.78–7.66

(m, 2.2H), 7.62–7.54 (m, 1.1H), 7.53–7.46 (m, 1.1H),

7.45–7.39 (m, 1H), 7.38–7.34 (m, 0.2H), 6.71 (d, J 8.9

Hz, 1H), 6.50 (d, J 3.7 Hz, 0.1H), 6.19 (dd, J 9.2, 10.7

Hz, 0.1H), 6.12 (dd, J 9.2, 10.7 Hz, 1H), 5.56 (dd, J 9.6,

9.4 Hz, 1H), 5.48 (dt, J 3.0, 9.9 Hz, 0.1H), 4.88 (dd, J

3.7, 11.5 Hz, 0.1H), 4.82 (d, J 14.3 Hz, 1.1H), 4.74 (d,

J 8.9 Hz, 1.1H), 4.67 (d, J 14.3 Hz, 1.1H), 4.48–4.37

(m, 1.1H), 4.31–4.12 (m, 2.2H), 2.14 (s, 0.3H), 2.09 (s,

3H), 1.99 (s, 0.3H), 1.84 (s, 3H); ¹³C NMR (125 MHz,

CDC1₃) l 170.9, 170.3, 165.1, 160.8, 138.0, 134.7,

134.6, 133.6, 131.5, 131.4, 130.3, 128.6, 127.6, 123.9,

93.8, 73.1, 70.4, 69.2, 61.9, 54.9, 53.9, 53.1, 21.0, 20.6;

ESI FT-MS: m/z (M+Na)⁺calcd 718.0487, obsd

718.0478.

n-Pentenyl 3,4-di-O-acetyl-2-deoxy-6-O-le6ulinyl-2-

phthalimido-i-D-glucopyranoside (E).—A solution of D

(2.36 g, 5.12 mmol) in CH₂Cl₂(40 mL) and pyridine (10

mL) was treated with DMAP (63 mg; 0.51 mmol) and

levulinic anhydride (1.64 g, 7.68 mmol). The solution

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

1901

3,4-Di-O-benzyl-2-deoxy-6-O-le6ulinyl-2-phthalimido-

i-D-glucopyranosyl trichloroacetimidate (F).—To

stirred solution of n-pentenyl 3,4-di-O-benzyl-2-deoxy-

2-phthalimido-b- -glucopyranoside (2.34 g, 4.21 mmol)

in CH₂Cl₂(30 mL) and pyridine (5 mL) was added

DMAP (51 mg, 0.42 mmol) and levulinic anhydride

(901 mg, 4.21 mmol). After 2 h shielded from light, the

solution was diluted with CH₂Cl₂(70 mL) and washed

with HCl (10% aq solution, 3×100 mL), H₂O (1×100

mL), brine (1×50 mL), dried over Na₂SO₄, ﬁltered,

and concentrated in vacuo. Puriﬁcation by ﬂash silica

gel chromatography (1:4 EtOAc–hexanes) yielded 2.29

g (83%) of the n-pentenyl 3,4-di-O-benzyl-2-deoxy-6-O-

was stirred for 2 h in the dark, then diluted with

CH₂Cl₂(60 mL) and washed with HCl (10% aq solu-

tion, 3×100 mL), H₂O (1×100 mL), brine (1×50

mL), and dried over Na₂SO₄. After ﬁltration and con-

centration in vacuo, the crude product was puriﬁed by

ﬂash silica gel chromatography (4:6 EtOAc–hexanes)

to afford 2.80 g (98%) of E as a white solid. [h]_D

+19.4° (c 1.03, CH₂Cl₂); IR (thin ﬁlm): 1748, 1717,

a

D

1388, 1225 cm⁻^{1 1}H NMR (400 MHz, CDCl₃) l

;

7.93–7.82 (m, 2H), 7.81–7.69 (m, 2H), 5.81 (dd, J 9.5,

10.4 Hz, 1H), 5.66–5.51 (m, 1H), 5.37 (d, J 8.5 Hz,

1H), 5.20 (dd, J 9.6, 9.7 Hz, 1H), 4.82–4.69 (m, 2H),

4.37–4.27 (m, 2H), 4.20 (d, J 12.2 Hz, 1H), 3.92–3.77

(m, 2H), 3.51–3.39 (m, 1H), 2.86–2.61 (m, 2H), 2.60–

2.40 (m, 2H), 2.16 (s, 3H), 2.11 (s, 3H), 1.92 (s, 3H),

1.90–1.79 (m, 2H), 1.58–1.44 (m, 2H); ¹³C NMR (100

MHz, CDCl₃) l 206.2, 171.5, 171.0, 170.7, 137.8, 134.5,

123.8, 115.0, 98.3, 72.1, 70.6, 69.5, 69.2, 62.2, 54.9, 37.9,

30.0, 29.8, 28.7, 28.6, 28.0, 21.0, 20.7; ESI FT-MS: m/z

(M+Na)⁺calcd 582.1952, obsd 582.1927.

levulinyl-2-phthalimido-b-D-glucopyranoside as a clear

oil. [h]_D+83.5° (c 1.00, CH₂Cl₂); IR (thin ﬁlm): 1777,

1

1716, 1387, 1056 cm⁻¹; H NMR (500 MHz, CDCl₃) l

7.86–7.55 (m, 4H), 7.41–7.19 (m, 5H), 7.04–6.99 (m,

2H), 6.93–6.83 (m, 3H), 5.60–5.50 (m, 1H), 5.14 (d, J

8.6 Hz, 1H), 4.91 (d, J 10.7 Hz, 1H), 4.83 (d, J 12.2 Hz,

1H), 4.76–4.66 (m, 3H), 4.64 (d, J 10.7 Hz, 1H), 4.47

(d, J 12.2 Hz, 1H), 4.44–4.29 (m, 3H), 4.17 (dd, J 8.2,

11.0 Hz, 1H), 3.76 (td, J 6.1, 9.8 Hz, 1H), 3.70 (d, J 4.9

Hz, 2H), 3.39 (td, J 6.1, 9.8 Hz, 1H), 2.83–2.70 (m,

2H), 2.68–2.59 (m, 2H), 2.20 (s, 3H), 1.89–1.74 (m,

2H), 1.56–1.40 (m, 2H); ¹³C NMR (125 MHz, CDCl₃)

l 206.5, 172.6, 137.9, 137.8, 137.7, 133.9, 128.7, 128.3,

128.2, 128.1, 128.0, 127.5, 123.4, 114.8, 98.3, 79.6, 79.5,

77.4, 75.2, 75.0, 73.0, 69.0, 63.2, 55.9, 38.0, 30.0, 29.9,

28.6, 28.1; ESI FT-MS: m/z (M+Na)⁺calcd 678.2678,

obsd 678.2675.

3,4-Di-O-acetyl-2-deoxy-6-O-le6ulinyl-2-phthalimido-

i-^D-glucopyranosyl trichloroacetimidate (8).—A solu-

tion of E (2.86 g, 5.12 mmol) in CH₃CN (50 mL) and

H₂O (5.0 mL) was treated with NBS (1.82 g, 10.2

mmol). After stirring for 13 h in the dark, the solution

was diluted with ether (100 mL) and washed with satd

Na₂S₂O₃(5×100 mL). The aqueous layer was ex-

tracted with ether (100 mL), and the combined organic

phases were washed with brine, dried over Na₂SO₄,

ﬁltered, and concentrated in vacuo to afford 2.01 g

(80%) of the crude lactol as a yellow oil. The crude

product (2.00 g, 4.07 mmol) was azeotroped with tolu-

ene (3×10 mL), dried under vacuum for 1 h, and

dissolved in CH₂Cl₂(40 mL). After cooling to 0 °C,

trichloroacetonitrile (5.80 g, 40.7 mmol) and DBU (44

mg, 0.41 mmol) were added, and the reaction mixture

was stirred for 2 h. The solution was concentrated in

vacuo and puriﬁed by ﬂash silica gel chromatography

(2:3 EtOAc–hexanes) to afford 1.93 g (74%, a:b=3:7)

of 8 as a clear oil. IR (thin ﬁlm): 1748, 1718, 1386, 1225

To a stirred solution of n-pentenyl 3,4-di-O-benzyl-2-

deoxy-6-O-levulinyl-2-phthalimido-b-D -glucopyran-

oside (3.80 g, 5.80 mmol) in CH₃CN (40 mL) and H₂O

(5 mL) was added NBS (3.09 g, 17.4 mmol). After

stirring for 13 h shielded form light, the reaction was

diluted with ether (100 mL) and washed with satd

Na₂S₂O₃(5×100 mL). The aqueous layer was ex-

tracted with ether (100 mL), and the combined organic

phases were washed with brine, dried over Na₂SO₄, and

concentrated in vacuo to afford 3.07 g (90%) of the

crude lactol as a yellow oil. The crude product (2.70 g,

4.60 mmol) was azeotroped with toluene (3×10 mL),

dried under vacuum for 1 h, and dissolved in CH₂Cl₂

(40.0 mL). After cooling to 0 °C, trichloroacetonitrile

(10.0 g, 69.4 mmol) and DBU (35 mg, 23 mmol) were

added, and the reaction mixture was stirred for 2 h. The

solution was concentrated in vacuo, and the crude

product was puriﬁed by ﬂash silica gel chromatography

(3:7 EtOAc–hexanes) to afford 3.11 g (93%) of F as a

yellow foam. [h]_D+60.9° (c 1.10, CH₂Cl₂); IR (thin

cm⁻^{1 1}H NMR (500 MHz, CDCl₃) l 8.66 (s, 1H),

;

7.86–7.81 (m, 2H), 7.76–7.68 (m, 2H), 6.75 (d, J 8.9

Hz, 0.7H), 6.71 (d, J 8.9 Hz, 0.3H), 5.95 (dd, J 9.2, 10.7

Hz, 0.3H), 5.93 (dd, J 9.2, 10.4 Hz, 0.7H), 5.30 (dd, J

9.2, 10.1 Hz, 1H), 4.62 (dd, J 9.2, 10.7 Hz, 1H), 4.39

(dd, J 4.6, 12.2 Hz, 0.3H), 4.38 (dd, J 4.3, 12.5 Hz,

0.7H), 4.22 (dd, J 2.1, 12.5 Hz, 0.7H), 4.21 (dd, J 2.4,

12.2 Hz, 0.3H), 4.08 (ddd, J 2.1, 4.3, 10.4 Hz, 1H),

2.83–2.64 (m, 2H), 2.59–2.45 (m, 2H), 2.14 (s, 2.1H),

2.13 (s, 0.9H), 2.11 (s, 2.1H), 2.09 (s, 0.9H), 1.98 (s,

0.9H), 1.94 (s, 2.1H); ¹³C NMR (125 MHz, CDCl₃) l

206.1, 171.5, 170.9, 160.7, 134.6, 131.4, 123.9, 93.8,

73.2, 73.0, 70.3, 68.6, 68.5, 61.7, 53.9, 53.8, 37.9, 28.0,

21.1, 20.8; ESI FT-MS: m/z (M+Na)⁺calcd 657.0422,

obsd 657.0403.

ﬁlm): 1777, 1716, 1387, 1062 cm^{−1 1}H NMR (400

;

MHz, CDCl₃) l 8.56 (s, 1H), 7.78–7.55 (m, 4H), 7.45–

7.18 (m, 5H), 7.14–6.98 (m, 2H), 6.97–6.78 (m, 3H),

6.41 (d, J 8.4 Hz, 1H), 4.92 (d, J 10.9 Hz, 1H), 4.85 (d,

J 12.1 Hz, 1H), 4.70 (d, J 10.9 Hz, 1H), 4.58–4.31 (m,

5H), 3.89 (td, J 3.5, 10.0 Hz, 1H), 3.83–3.74 (m, 1H),

1902

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

2.85–2.71 (m, 2H), 2.70–2.58 (m, 2H), 2.20 (s, 3H); ¹³C

NMR (125 MHz, CDCl₃) l 206.8, 172.7, 167.8, 160.8,

137.9, 137.6, 134.2, 131.5, 128.8, 128.4, 128.3, 127.7,

123.5, 94.1, 90.5, 79.2, 78.9, 77.4, 75.3, 75.2, 74.0, 62.7,

54.7, 38.0, 29.9, 28.1; ESI FT-MS: m/z (M+Na)⁺

calcd 753.1150, obsd 753.1151.

20.9, 20.6, 18.6, 18.5, 13.7, 13.5; ³¹P NMR (120 MHz,

CDCl₃): −2.73 (s, 1P); ESI FT-MS: m/z (M+Na)⁺

calcd 706.2241, obsd 706.2246.

n-Pentenyl

glucopyranoside (G).—To a stirred solution of n-

pentenyl 3,4-di-O-benzyl-2-deoxy-2-phthalimido-b-

2-amino-3,4-di-O-benzyl-2-deoxy-i-D-

D-

3,4-Di-O-benzyl-2-deoxy-6-O-le6ulinyl-2-phthalimido-

h,i-^D-glucopyranose, 1-dibutylphosphate (10).—Glu-

cosamine trichloroacetimidate F (3.00 g, 4.10 mmol)

was azeotroped with toluene (3×5 mL), and dissolved

in toluene (40 mL). Dibutyl phosphate (1.12 g, 5.33

mmol) was added, and the solution was stirred for 14 h.

After concentration in 6acuo, the crude product was

puriﬁed by ﬂash silica gel chromatography (1:1

EtOAc–hexanes) to afford 4.02 g (98%, a:b=1:4) of 10

as a yellow oil. IR (thin ﬁlm): 1777, 1717, 1387, 1028

glucopyranoside (2.06 g, 3.71 mmol) in dry EtOH (20

mL) was added ethylenediamine (11.1 g, 0.19 mol), and

the solution reﬂuxed for 16 h. After concentration in

vacuo, the crude product was dissolved in EtOAc (50

mL) and washed with HCl (10% in H₂O, 3×20 mL),

H₂O, brine, dried over Na₂SO₄, ﬁltered and concen-

trated in vacuo. Puriﬁcation by ﬂash silica gel chro-

matography (3:2 EtOAc–hexanes) afforded 1.58 g

(100%) of G as a white solid. [h]_D−6.54° (c 0.95,

CH₂Cl₂); IR (thin ﬁlm): 2871, 1097, 1049, 698 cm⁻¹

;

cm⁻¹; H NMR (500 MHz, CDCl₃) l 7.77–7.65 (m,

¹H NMR (400 MHz, CDCl₃) l 7.43–7.28 (m, 10H),

5.90–5.75 (m, 1H), 5.09–4.96 (m, 3H), 4.86 (d, J 10.9

Hz, 1H), 4.75 (d, J 10.9 Hz, 1H), 4.70 (d, J 10.9 Hz,

1H), 4.25 (d, J 7.9 Hz, 1H), 3.97–3.86 (m, 2H), 3.77

(dd, J 4.3, 12.0 Hz, 1H), 3.65 (dd, J 9.2, 9.4 Hz, 1H),

3.58–3.45 (m, 2H), 3.44–3.36 (m, 1H), 2.85 (dd, J 8.0,

10.0 Hz, 1H), 2.21–2.07 (m, 2H), 1.80 (br s, 3H),

1.79–1.63 (m, 2H); ¹³C NMR (100 MHz, CDCl₃) l

138.4, 138.1, 138.0, 128.7, 128.5, 128.2, 128.1, 128.0,

115.2, 104.0, 84.9, 78.4, 75.6, 75.1, 69.6, 61.9, 57.1, 30.3,

28.9; ESI FT-MS: m/z (M+Na)⁺calcd 450.2257, obsd

450.2253.

1

4H), 7.38–7.29 (m, 5H), 7.09–6.98 (m, 2H), 6.95–6.82

(m, 3H), 5.83 (dd, J 8.2, 7.6 Hz, 0.8H), 5.70 (dd, J 3.4,

6.7 Hz, 0.2H), 5.27 (dd, J 8.9, 11.0 Hz, 0.2H), 4.96 (d,

J 11.9 Hz, 0.2H), 4.89 (d, J 10.7 Hz, 0.8H), 4.49 (dd, J

8.5, 10.7 Hz, 1H), 4.46–4.39 (m, 2H), 4.32 (dd, J 4.6,

12.2 Hz, 1H), 4.24 (dd, J 8.5, 10.7 Hz, 1H), 4.00–3.86

(m, 2H), 3.81 (ddd, J 1.8, 4.0, 10.1 Hz, 1H), 3.78–3.73

(m, 3H), 2.84–2.69 (m, 2H), 2.67–2.54 (m, 2H), 2.20 (s,

3H), 1.57–1.48 (m, 2H), 1.35–1.23 (m, 4H), 1.09–1.00

(m, 2H), 0.90–0.81 (m, 3H), 0.74–0.66 (m, 3H); ¹³C

NMR (125 MHz, CDCl₃) l 206.5, 172.5, 137.8, 137.5,

134.0, 131.6, 128.7, 128.3, 128.2, 127.9, 127.6, 126.9,

123.5, 94.1, 78.9, 78.7, 75.3, 75.2, 73.7, 68.1, 67.9, 62.6,

56.2, 38.0, 32.0, 31.9, 30.0, 27.9, 18.6, 18.4, 13.7, 13.5;

³¹P NMR (120 MHz, CDCl₃): −2.01 (s, 0.2P), −2.70

(s, 0.8P); ESI FT-MS: m/z (M+Na)⁺calcd 802.2969,

obsd 802.2933.

n-Pentenyl 6-O-acetyl-3,4-di-O-benzyl-2-benzyloxy-

carbonylamino-2-deoxy-i-D-glucopyranoside (H).—To

a vigorously stirred solution of amine G (1.50 g, 3.51

mmol) in H₂O (20 mL) and Et₂O (20 mL) was added

NaHCO₃(1.17 g, 14.0 mmol) and benzyl chloroformate

(0.89 g, 5.26 mmol). After 1 h, the solution was parti-

tioned between organic and aqueous layers, and the

aqueous layer was extracted with Et₂O (2×20 mL).

The combined organic phases were washed with H₂O,

brine, and dried over Na₂SO₄. After ﬁltration and

concentration in vacuo, the crude product was puriﬁed

by ﬂash silica gel chromatography (3:2 EtOAc–hex-

anes) to afford 1.59 g (81%) of n-pentenyl 3,4-di-O-

3,4-Di-O-acetyl-2-deoxy-6-O-le6ulinyl-2-phthalimido-

i-D-glucopyranose-1-dibutylphosphate

(12).—Glu-

cosamine trichloroacetimidate 8 (4.85 g, 7.64 mmol)

was azeotroped with toluene (3×5 mL) and dissolved

in toluene (40 mL). Dibutyl phosphate (2.08 g, 9.94

mmol) was added, and the solution was stirred for 14 h.

After concentration in vacuo, the crude product was

puriﬁed by ﬂash silica gel chromatography (1:1

EtOAc–hexanes) to afford 2.72 g (52%) of 12 as a clear

oil. [h]_D+25.9° (c 0.97, CH₂Cl₂); IR (thin ﬁlm): 1750,

benzyl-2-benzyloxycarbonylamino-2-deoxy-b-D-glucopyr

anoside as a white solid. [h]_D+1.21° (c 0.67, CH₂Cl₂);

1

IR (thin ﬁlm): 3306, 1693, 1548, 1089 cm⁻¹; H NMR

1720, 1386, 1224, 1028 cm⁻¹

;

¹H NMR (400 MHz,

(500 MHz, CDCl₃) l 7.38–7.20 (m, 15H), 5.83–5.70

(m, 1H), 5.09 (s, 2H), 5.01 (ddd, J 1.5, 3.4, 17.1 Hz,

1H), 4.98–4.89 (m, 1H), 4.86 (d, J 11.0 Hz, 1H), 4.80

(d, J 11.3 Hz, 1H), 4.68 (d, J 11.3 Hz, 1H), 4.64 (d, J

11.6 Hz, 1H), 4.00 (br s, 1H), 3.90–3.81 (m, 2H), 3.73

(dd, J 4.0, 11.6 Hz, 1H), 3.58 (t, J 9.2 Hz, 1H),

3.50–3.38 (m, 2H), 3.25 (br s, 1H), 2.14–2.01 (m, 2H),

1.96 (br s, 1H), 1.72–1.56 (m, 2H); ¹³C NMR (125

MHz, CDCl₃) l 156.0, 138.2, 138.1, 136.6, 128.7, 128.6,

128.4, 128.3, 128.2, 128.0, 115.2, 101.8, 78.6, 75.2, 75.1,

69.5, 66.9, 62.1, 58.3, 30.1, 28.8; ESI FT-MS: m/z

(M+Na)⁺calcd 584.2625, obsd 584.2622.

CDCl₃) l 7.94–7.81 (m, 2H), 7.81–7.67 (m, 2H), 6.06

(dd, J 7.5, 8.3 Hz, 1H), 5.90 (dd, J 9.2, 10.7 Hz, 1H),

5.23 (dd, J 9.4, 10.1 Hz, 1H), 4.40 (dd, J 8.5, 10.7 Hz,

1H), 4.32 (dd, J 4.8, 12.5 Hz, 1H), 4.21 (dd, J 2.0, 12.5

Hz, 1H), 4.07–3.92 (m, 3H), 3.84–3.62 (m, 2H), 2.84–

2.63 (m, 2H), 2.62–2.40 (m, 2H), 2.15 (s, 3H), 2.10 (s,

3H), 1.92 (s, 3H), 1.62–1.51 (m, 2H), 1.39–1.23 (m,

4H), 1.16–1.01 (m, 2H), 0.94–0.84 (m, 3H), 0.76–0.66

(m, 3H); ¹³C NMR (100 MHz, CDCl₃) l 206.2, 171.5,

170.8, 170.4, 134.6, 131.6, 123.8, 93.8, 72.7, 69.9, 68.4,

68.2, 68.0, 61.7, 55.1, 37.8, 32.1, 32.0, 31.9, 29.8, 27.9,

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

1903

To a stirred solution of n-pentenyl 3,4-di-O-benzyl-2-

benzyloxycarbonylamino-2-deoxy-b- -glucopyranoside

72.1, 67.4, 62.5, 54.4, 21.0; ESI FT-MS: m/z (M+

Na)⁺calcd 701.1195, obsd 701.1193.

n-Pentenyl 2-benzyloxycarbonylamino-2-deoxy-i-D-

glucopyranoside (J).—To a stirred solution of I (15.7 g,

32.6 mmol) in CH₂Cl₂(300 mL) at 0 °C was added

D

(1.59 g, 2.83 mmol) in CH₂Cl₂(20 mL) and pyridine (10

mL) was added DMAP (35 mg, 0.28 mmol) and Ac₂O

(0.58 g, 5.67 mmol). After 2 h, the solution was diluted

with CH₂Cl₂(100 mL), washed with HCl (10% aq

solution, 3×100 mL), H₂O (1×100 mL), brine (1×50

mL), dried over Na₂SO₄, ﬁltered and concentrated in

vacuo. Puriﬁcation by ﬂash silica gel chromatography

(1:4 EtOAc–hexanes) yielded 1.66 g (96%) of H as a

white solid. [h]_D+6.16° (c 0.73, CH₂Cl₂); IR (thin

,

BF₃·Et₂O (6.94 g, 48.9 mmol), ﬂame-dried 4 A molecu-

lar sieves (5.0 g) and 4-penten-1-ol (7.0 g, 81.5 mmol).

The reaction mixture was stirred for 48 h at ambient

temperature, diluted with CH₂Cl₂(100 mL), and

washed with satd NaHCO₃(3×100 mL). The aqueous

layer was extracted with CH₂Cl₂(100 mL), and the

combined organic phases were washed with brine and

dried over Na₂SO₄. After ﬁltration and concentration in

vacuo, the crude product was puriﬁed by ﬂash silica gel

chromatography (2:3 EtOAc–hexanes) to afford 8.88 g

(54%) of n-pentenyl 3,4,6-tri-O-acetyl-2-benzyloxycar-

ﬁlm): 3342, 1735, 1699, 1536, 1244 cm⁻^{1 1}H NMR

;

(500 MHz, CDCl₃) l 7.38–7.23 (m, 15H), 5.83–5.74

(m, 1H), 5.09 (br s, 2H), 5.01 (ddd, J 1.8, 3.7, 17.4 Hz,

1H), 4.98 (dd, J 1.8, 8.6 Hz, 1H), 4.85 (d, J 11.0 Hz,

1H), 4.78 (d, J 11.0 Hz, 1H), 4.66 (d, J 11.0 Hz, 1H),

4.58 (d, J 11.0 Hz, 1H), 4.35 (d, J 12.2 Hz, 1H), 4.24

(dd, J 4.6, 11.6 Hz, 1H), 4.03 (bs, 1H), 3.85 (td, J 6.1,

9.8 Hz, 1H), 3.61–3.52 (m, 2H), 3.49–3.41 (m, 1H),

3.28 (br s, 1H), 2.13–2.01 (m, 2H), 2.04 (s, 3H), 1.71–

1.56 (m, 2H); ¹³C NMR (125 MHz, CDCl₃) l 171.0,

155.9, 138.2, 137.8, 136.6, 128.7, 128.6, 128.4, 128.3,

128.2, 128.0, 115.1, 100.8, 78.4, 75.2, 75.0, 73.0, 69.5,

67.0, 63.4, 58.1, 30.2, 28.9, 21.1; ESI FT-MS: m/z

(M+Na)⁺calcd 626.2730, obsd 626.2703.

bonylamino-2-deoxy-b-

solid. [h]_D+2.5° (c 1.06, CH₂Cl₂); IR (thin ﬁlm): 3344,

1746, 1702, 1539, 1235 cm^{−1 1}H NMR (400 MHz,

D-glucopyranoside as a white

;

CDCl₃) l 7.46–7.21 (m, 5H), 5.89–5.66 (m, 1H), 5.42–

5.21 (m, 1H), 5.21–5.01 (m, 3H), 4.96 (d, J 11.3 Hz,

2H), 4.72–4.53 (m, 1H), 4.27 (dd, J 4.6, 12.2 Hz, 1H),

4.12 (d, J 12.2 Hz, 1H), 3.96–3.80 (m, 1H), 3.75–3.55

(m, 2H), 3.55–3.39 (m, 1H), 2.08 (s, 3H), 2.16–2.05 (m,

2H), 2.02 (s, 3H), 1.96 (s, 3H), 1.75–1.52 (m, 2H); ¹³C

NMR (100 MHz, CDCl₃) l 171.0, 170.9, 169.7, 155.9,

138.1, 136.4, 128.7, 128.6, 128.4, 115.2, 101.2, 77.4,

72.2, 71.8, 69.6, 68.9, 67.1, 62.3, 56.3, 30.0, 28.7, 21.0,

20.8; ESI FT-MS: m/z (M+Na)⁺calcd 530.1997, obsd

530.1983.

6-O - Acetyl - 3,4 - di - O - benzyl - 2 - benzyloxycarbonyl-

amino-2-deoxy-h-D-glucopyranosyl trichloroacetimidate

(14).—To a stirred solution of H (1.66 g, 2.75 mmol) in

CH₃CN (20 mL) and H₂O (2.5 mL) was added NBS

(1.47 g, 8.26 mmol). The reaction mixture was shielded

from light and stirred for 12 h, diluted with ether (100

mL), and washed with satd Na₂S₂O₃(5×50 mL). The

aqueous layer was extracted with ether (100 mL), and

the combined organic phases were washed with brine

and dried over Na₂SO₄. After ﬁltration and concentra-

tion in vacuo, the crude product was azeotroped with

toluene (3×10 mL), dried under vacuum for 1 h, and

dissolved in CH₂Cl₂(20.0 mL). After cooling to 0 °C,

trichloroacetonitrile (7.92 g, 55.0 mmol) and DBU (209

mg, 1.38 mmol) were added and the reaction mixture

was stirred for 2 h. The solution was concentrated in

vacuo, and puriﬁed by ﬂash silica gel chromatography

(3:7 EtOAc–hexanes) to afford 1.19 g (64%) of 14 as a

white foam. [h]_D+50.5° (c 0.34, CH₂Cl₂); IR (thin

A solution of n-pentenyl 3,4,6-tri-O-acetyl-2-benzy-

loxycarbonylamino-2-deoxy-b-D-glucopyranoside (2.40

g, 4.73 mmol) in dry MeOH (50 mL) was treated with

NaOMe (310 mL, 1.42 mmol, 25% w/v in MeOH). The

reaction mixture was stirred for 14 h, then quenched by

the addition of strongly acidic ion-exchange resin until

the pH of the solution reached 5–6. After ﬁltration and

concentration in vacuo, the crude product was puriﬁed

by ﬂash silica gel chromatography (3:2 EtOAc–hex-

anes) to afford 1.77 g (98%) of J as an orange solid.

[h]_D−20.2° (c 0.60, CH₂Cl₂); IR (thin ﬁlm): 3296,

1

1694, 1558, 1077 cm⁻¹; H NMR (400 MHz, CD₃OD)

l 7.49–6.97 (m, 5H), 5.88–5.54 (m, 1H), 5.17–4.92 (m,

3H), 4.27 (d, J 7.9 Hz, 1H), 3.96–3.69 (m, 2H), 3.60

(dd, J 5.7, 11.9 Hz, 1H), 3.47–3.29 (m, 3H), 3.21–2.99

(m, 1H), 2.14–1.82 (m, 2H), 1.70–1.29 (m, 2H); ¹³C

NMR (100 MHz, CD₃OD) l 159.2, 139.6, 138.5, 129.6,

129.1, 129.0, 115.5, 103.3, 78.0, 76.1, 72.3, 70.1, 67.6,

62.9, 59.2, 31.4, 30.1; ESI FT-MS: m/z (M+Na)⁺

calcd 404.1680, obsd 404.1670.

ﬁlm): 3311, 1724, 1515, 1240, 1025 cm^{−1 1}H NMR

;

(500 MHz, CDCl₃) l 8.67 (s, 1H), 7.41–7.25 (m, 15H),

6.27 (d, J 3.7 Hz, 1H), 5.15 (d, J 12.2 Hz, 1H), 5.03 (d,

J 12.2 Hz, 1H), 4.89 (d, J 11.0 Hz, 2H), 4.75 (d, J 10.7

Hz, 1H), 4.72 (d, J 11.0 Hz, 1H), 4.62 (d, J 10.7 Hz,

1H), 4.43 (d, J 9.8 Hz, 1H), 4.31 (dd, J 2.1, 12.2 Hz,

1H), 4.24 (dd, J 3.7, 11.9 Hz, 1H), 4.19 (dt, J 3.4, 10.1

Hz, 1H), 4.01–3.95 (m, 1H), 3.86 (dd, J 6.1, 6.4 Hz,

1H), 3.84–3.78 (m, 1H), 3.71–3.78 (m, 2H), 2.96 (dd, J

6.1, 6.4 Hz, 1H), 2.03 (s, 3H); ¹³C NMR (125 MHz,

CDCl₃) l 170.8, 160.5, 156.1, 137.7, 137.4, 136.3, 128.8,

128.7, 128.6, 128.5, 128.3, 96.1, 91.1, 79.4, 75.6, 75.4,

n-Pentenyl

3,4-di-O-acetyl-2-benzyloxycarbonyl-

amino-2-deoxy-6-O-triisopropylsilyl-i-D -glucopyrano-

side (K).—To a stirred solution of J (1.70 g, 4.46

mmol) in dry DMF (40 mL) at 0 °C, was added imida-

zole (0.36 g, 5.35 mmol) and triisopropylchlorosilane

(1.03 g, 5.35 mmol). After 14 h, the reaction was

1904

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

quenched by the addition of water (100 mL). The

aqueous layer was extracted with ether (3×100 mL),

and the combined organic phases were washed with

brine, dried over Na₂SO₄, ﬁltered, and concentrated in

vacuo. Puriﬁcation by ﬂash silica gel chromatography

(3:2 EtOAc–hexanes) afforded 2.27 g (95%) of n-pen-

solid. [h]_D−31.9° (c 0.98, CH₂Cl₂); IR (thin ﬁlm):

3342, 1741, 1540, 1239 cm^{−1 1}H NMR (400 MHz,

;

CDCl₃) l 7.38–7.27 (m, 5H), 5.84–5.66 (m, 1H), 5.27

(d, J 8.0 Hz, 1H), 5.14–5.03 (m, 3H), 5.02–4.98 (m,

2H), 4.49 (d, J 5.9 Hz, 1H), 4.44–4.27 (m, 2H), 3.85

(td, J 6.2, 9.6 Hz, 1H), 3.68–3.56 (m, 1H), 3.56–3.49

(m, 2H), 3.49–3.40 (m, 2H), 2.10 (s, 3H), 2.08–2.02 (m,

2H), 2.00 (s, 3H), 1.75–1.54 (m, 2H); ¹³C NMR (100

MHz, CDCl₃) l 172.0, 171.9, 156.3, 138.1, 136.6, 128.6,

128.1, 115.1, 101.4, 77.4, 75.1, 73.9, 69.4, 69.2, 66.9,

63.4, 61.4, 56.0, 30.0, 28.7, 20.8; ESI FT-MS: m/z

(M+Na)⁺calcd, 488.1891, obsd 488.1882.

tenyl

propylsilyl-b-

2-benzyloxycarbonylamino-2-deoxy-6-O-triiso-

-glucopyranoside as a white solid. [h]_D

D

−26.7° (c 0.88, CH₂Cl₂), IR (thin ﬁlm): 3328, 1699,

1540, 1254, 1062 cm⁻¹; H NMR (500 MHz, CDCl₃) l

1

7.38–7.26 (m, 5H), 5.82–5.70 (m, 1H), 5.18–5.06 (m,

3H), 5.00 (dd, J 1.5, 17.1 Hz, 1H), 4.98 (dd, J 1.2, 10.1

Hz, 1H), 4.42 (br s, 1H), 4.01–3.89 (m, 2H), 3.84 (td, J

6.4, 9.5 Hz, 1H), 3.57 (dd, J 8.9, 9.2 Hz, 2H), 3.48–3.38

(m, 2H), 3.31 (br s, 1H), 2.08 (dd, J 7.3, 14.3 Hz, 2H),

1.72–1.58 (m, 2H), 1.20–0.92 (m, 21H); ¹³C NMR (125

MHz, CDCl₃) l 157.2, 138.2, 136.3, 128.7, 128.4, 115.2,

101.3, 74.9, 74.0, 69.2, 67.4, 65.3, 58.1, 30.3, 28.8, 18.1,

12.0; ESI FT-MS: m/z (M+Na)⁺calcd 560.3020, obsd

560.3032.

To a stirred solution of n-pentenyl 3,4-di-O-acetyl-2-

benzyloxycarbonylamino-2-deoxy-b-D-glucopyranoside

(1.57 g, 3.39 mmol) in CH₂Cl₂(30 mL) and pyridine (10

mL) was added DMAP (41 mg, 0.34 mmol) and

levulinic anhydride (1.36 g, 6.38 mmol). After 2 h in the

dark, the reaction was diluted with CH₂Cl₂(60 mL),

washed with HCl (10% aq solution, 3×100 mL), H₂O

(100 mL), brine (50 mL), dried over Na₂SO₄, ﬁltered,

and concentrated in vacuo. Puriﬁcation by ﬂash silica

gel chromatography (2:3 EtOAc–hexanes) yielded 1.77

g (94%) of L as a white solid. [h]_D+3.30° (c 1.01,

CH₂Cl₂); IR (thin ﬁlm): 3335, 1748, 1540, 1365, 1231

To a stirred solution of n-pentenyl 2-benzyloxycar-

bonylamino-2-deoxy-6-O-triisopropylsilyl-b-D-glucopy-

ranoside (2.27 g, 4.22 mmol) in CH₂Cl₂(30 mL) and

pyridine (10 mL) was added DMAP (52 mg, 0.42

mmol) and Ac₂O (1.30 g, 12.6 mmol). After 2 h, the

solution was diluted with CH₂Cl₂(70 mL), washed with

HCl (10% aq solution, 3×100 mL), H₂O (100 mL),

brine (50 mL), dried over Na₂SO₄, ﬁltered, and concen-

trated in vacuo. Puriﬁcation by ﬂash silica gel chro-

1

cm⁻¹; H NMR (500 MHz, CDCl₃) l 7.38–7.28 (m,

5H), 5.81–5.71 (m, 1H), 5.29 (br s, 1H), 5.15–5.04 (m,

4H), 5.00 (ddd, J 1.5, 3.4, 17.1 Hz, 1H), 4.95 (ddd, J

0.9, 1.8, 10.1 Hz, 1H), 4.86 (br s, 1H), 4.60 (br s, 1H),

4.25 (dd, J 5.2, 12.5 Hz, 1H), 4.12 (dd, J 1.8, 12.2 Hz,

1H), 3.88 (td, J 6.1, 9.8 Hz, 1H), 3.72–3.54 (m, 2H),

3.50–3.42 (m, 1H), 2.70–2.60 (m, 2H), 2.16 (s, 3H),

2.12–2.05 (m, 2H), 2.08 (s, 3H), 2.02 (s, 3H), 1.72–1.57

(m, 2H); ¹³C NMR (100 MHz, CDCl₃) l 206.2, 171.6,

171.1, 170.9, 155.9, 138.1, 136.5, 128.6, 128.2, 115.2,

101.3, 71.9, 69.6, 68.9, 67.1, 62.3, 56.4, 37.8, 30.0, 29.8,

28.7, 27.9, 26.3, 21.0, 20.8; ESI FT-MS: m/z (M+

Na)⁺calcd 586.2259, obsd 586.2255.

matography (3:2 EtOAc–hexanes) yielded 2.62

(100%) of K as a white solid. [h]_D+10.3° (c 0.95,

CH₂Cl₂); IR (thin ﬁlm): 3284, 1749, 1692, 1238 cm⁻¹

g

;

¹H NMR (400 MHz, CDCl₃) l 7.43–7.28 (m, 5H),

5.83–5.69 (m, 1H), 5.24 (br s, 1H), 5.09 (br s, 2H),

5.05–4.98 (m, 2H), 4.97–4.88 (m, 2H), 4.54 (br s, 1H),

3.85 (td, J 6.3, 9.5 Hz, 1H), 3.80–3.71 (m, 2H), 3.61 (d,

J 8.0 Hz, 1H), 3.53 (d, J 9.2 Hz, 1H), 3.46 (dd, J 6.9,

15.9 Hz, 1H), 2.12–2.02 (m, 2H), 1.99 (s, 3H), 1.95 (s,

3H), 1.73–1.55 (m, 2H), 1.13–0.92 (m, 21H); ¹³C NMR

(100 MHz, CDCl₃) l 171.1, 169.6, 156.0, 138.2, 136.5,

128.6, 128.2, 115.0, 101.0, 77.4, 75.0, 72.9, 69.4, 69.1,

67.0, 62.9, 56.3, 30.1, 28.8, 20.8, 18.0, 12.3; ESI FT-MS:

m/z (M+Na)⁺calcd 644.3225, obsd 644.3203.

3,4-Di-O-acetyl-2-benzyloxycarbonylamino-2-deoxy-

6-O-le6ulinyl-i-D-glucopyranosyl

trichloroacetimidate

(16).—To a stirred solution of n-pentenyl glycoside L

(1.77 g, 3.14 mmol) in CH₃CN (20 mL) and H₂O (2

mL) was added NBS (1.12 g, 6.29 mmol). After 13 h

shielded from light, the solution was diluted with Et₂O

(100 mL) and washed with satd Na₂S₂O₃(5×100 mL).

The aqueous layer was extracted with Et₂O (100 mL),

and the combined organic phases were washed with

brine, dried over Na₂SO₄, and concentrated in vacuo to

afford the crude lactol as a yellow oil. The crude

product was azeotroped with toluene (3×10 mL),

dried under vacuum for 1 h, and dissolved in CH₂Cl₂

(30 mL). After cooling to 0 °C, trichloroacetonitrile

(2.91 g, 20.2 mmol) and DBU (108 mg, 1.01 mmol)

were added, and the reaction mixture was stirred for 2

h. The solution was concentrated in vacuo and puriﬁed

by ﬂash silica gel chromatography (2:3 EtOAc–hex-

anes) to afford 730 mg (57%) of 16 as a white foam.

n-Pentenyl

3,4-di-O-acetyl-2-benzyloxycarbonyl-

amino-2-deoxy-6-O-le6uliny-i-D-glucopyranoside (L).

—To a stirred solution of K (2.64 g, 4.25 mmol) in

THF (40 mL) was added AcOH (250 mL, 4.25 mmol)

and TBAF (6.4 mL, 6.4 mmol, 1 M in THF). After 12

h, the reaction was quenched by the addition of satd

NaHCO₃(50 mL), and the aqueous layer was extracted

with ether (3×100 mL). The combined organic phases

were washed with brine and dried over Na₂SO₄, ﬁltered,

and concentrated in vacuo. Puriﬁcation by ﬂash silica

gel chromatography (2:3 EtOAc–hexanes) afforded

1.66 g (84%) of n-pentenyl 3,4-di-O-acetyl-2-benzyloxy-

carbonylamino-2-deoxy-b-D-glucopyranoside as a white

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

1905

[h]_D+57.3° (c 0.96, CH₂Cl₂); IR (thin ﬁlm): 3320,

MHz, CDCl₃) l 7.37–7.21 (m, 15H), 5.65–5.60 (m,

1H), 5.16 (d, J 12.2 Hz, 1H), 5.05 (d, J 12.2 Hz, 1H),

4.87 (d, J 11.0 Hz, 1H), 4.84 (d, J 11.0 Hz, 1H), 4.70 (d,

J 11.0 Hz, 1H), 4.61 (d, J 11.0 Hz, 1H), 4.33 (dd, J 3.7,

12.2 Hz, 1H), 4.27 (dd, J 1.8, 11.9 Hz, 1H), 4.01–3.98

(m, 6H), 3.76–3.66 (m, 2H), 2.82–2.68 (m, 2H), 2.62–

2.55 (m, 2H), 2.19 (s, 3H), 1.83–1.70 (m, 2H), 1.68–

1.57 (m, 4H), 1.43–1.31 (m, 4H), 0.98–0.85 (m, 6H);

¹³C NMR (125 MHz, CDCl₃) l 206.5, 172.5, 156.0,

137.9, 137.8, 137.7, 137.6, 136.4, 136.3, 128.7, 128.6,

128.4, 128.3, 128.2, 128.1, 97.2, 96.9, 81.1, 79.7, 77.3,

75.5, 75.4, 75.1, 73.8, 71.3, 68.1, 67.3, 67.0, 62.9, 62.5,

57.3, 55.0, 38.0, 32.4, 32.3, 32.2, 30.0, 28.0, 18.8, 13.8;

³¹P NMR (120 MHz, CDCl₃): −1.57 (s, 0.5P), −1.94

(s, 0.5P); ESI FT-MS: m/z (M+Na)⁺calcd 806.3282,

obsd 806.3281.

1

1744, 1521, 1226 cm⁻¹; H NMR (400 MHz, CDCl₃) l

8.78 (s, 1H), 7.40–7.24 (m, 5H), 6.37 (d, J 3.7 Hz, 1H),

5.32–5.07 (m, 3H), 5.01 (d, J 11.9 Hz, 2H), 4.32–4.18

(m, 2H), 4.17–4.05 (m, 2H), 2.83–2.64 (m, 2H), 2.63–

2.51 (m, 2H), 2.16 (s, 3H), 2.01 (s, 3H), 1.90 (s, 3H); ¹³

C

NMR (100 MHz, CDCl₃) l 206.5, 177.7, 172.3, 171.1,

169.4, 160.3, 155.8, 135.8, 128.6, 128.4, 128.2, 94.9,

90.8, 77.4, 70.6, 67.6, 67.2, 61.8, 53.7, 37.9, 29.9, 27.9,

20.6; ESI FT-MS: m/z (M+Na)⁺calcd 661.0735, obsd

661.0734.

n-Pentenyl

3,4-di-O-benzyl-2-benzyloxycarbonyl-

amino-2-deoxy-6-O-le6ulinyl-i-D-glucopyranoside (M).

—To a stirred solution of n-pentenyl 3,4-di-O-benzyl-

2-deoxy-2-benzyloxycarbonylamino-b-D-glucopyrano-

side (1.58 g, 2.82 mmol) in CH₂Cl₂(25 mL) and pyri-

dine (5 mL) was added DMAP (34 mg, 0.28 mmol) and

levulinic anhydride (1.13 g, 5.26 mmol). After 2 h

shielded from light, the reaction was diluted with

CH₂Cl₂(70 mL), washed with HCl (10% v/v in H₂O,

3×100 mL), H₂O (100 mL), brine (50 mL), dried over

Na₂SO₄, ﬁltered, and concentrated in vacuo. Puriﬁca-

tion by ﬂash silica gel chromatography (20% EtOAc/

hexanes) afforded 1.73 g (93%) of M as a clear oil. [h]_D

+1.79° (c 0.56, CH₂Cl₂); IR (thin ﬁlm): 3323, 1734,

3,4-Di-O-acetyl-2-benzyloxycarbonylamino-2-deoxy-

6-O-le6ulinyl-i-D-glucopyranose,

1-dibutylphosphate

(20).—Glucosamine trichloroacetimidate 16 (135 mg,

211 mmol) was azeotroped with toluene (3×5 mL), and

dissolved in toluene (2 mL). Dibutyl phosphate (48 mg,

232 mmol) was added, and the solution was stirred for

14 h. After concentration in vacuo, the crude product

was puriﬁed by ﬂash silica gel chromatography (1:1

EtOAc–hexanes) to afford 103 mg (72%) of 20 as a

clear oil. [h]_D+23.6° (c 0.95, CH₂Cl₂); IR (thin ﬁlm):

1696, 1543 cm^{−1 1}H NMR (400 MHz, CDCl₃) l

;

7.42–7.22 (m, 15H), 5.86–5.71 (m, 1H), 5.09 (s, 2H),

5.04–4.93 (m, 3H), 4.85 (d, J 10.8 Hz, 1H), 4.79 (d, J

11.0 Hz, 1H), 4.72–4.63 (m, 2H), 4.60 (d, J 10.8 Hz,

1H), 4.36 (d, J 11.6 Hz, 1H), 4.31–4.22 (m, 1H), 4.01

(br s, 1H), 3.85 (td, J 6.2, 9.6 Hz, 1H), 3.59–3.51 (m,

2H), 3.51–3.39 (m, 1H), 3.29 (br s, 1H), 2.81–2.67 (m,

2H), 2.65–2.56 (m, 2H), 2.21 (s, 3H), 2.14–1.99 (m,

2H), 1.67–1.56 (m, 2H); ¹³C NMR (125 MHz, CDCl₃)

l 206.7, 172.7, 156.2, 138.3, 138.2, 137.9, 136.6,

128.7,128.6, 128.2, 128.1, 128.0, 115.1, 101.2, 78.4, 75.2,

75.0, 72.9, 69.4, 66.9, 63.5, 58.0, 38.0, 30.2, 28.8, 28.1;

ESI FT-MS: m/z (M+Na)⁺calcd 682.2992, obsd

682.2964.

3355, 1716, 1539, 1236 cm^{−1 1}H NMR (500 MHz,

;

CDCl₃) l 7.40–7.28 (m, 5H), 5.30–5.22 (m, 2H), 5.20–

5.07 (m, 3H), 5.01 (d, J 12.5 Hz, 1H), 4.24 (dd, J 4.9,

12.5 Hz, 1H), 4.15 (d, J 12.3 Hz, 1H), 4.09–4.01 (m,

2H), 3.99–3.86 (m, 3H), 3.81–3.75 (m, 1H), 2.80–2.72

(m, 1H), 2.70–2.62 (m, 1H), 2.55–2.40 (m, 2H), 2.15 (s,

3H), 2.06 (s, 3H), 1.98 (s, 3H), 1.67–1.60 (m, 2H),

1.57–1.49 (m, 2H), 1.42–1.35 (m, 2H), 1.34–1.25 (m,

2H), 0.92 (t, J 7.3 Hz, 3H), 0.88 (t, J 7.3 Hz, 3H); ¹³C

NMR (125 MHz, CDCl₃) l 206.1, 171.5, 171.2, 170.8,

136.4, 128.7, 128.4, 128.1, 97.0, 72.8, 72.0, 68.3, 68.2,

68.1, 67.0, 61.9, 56.3, 37.9, 32.2, 29.8, 27.9, 20.9, 20.7,

19.0, 18.8, 18.7, 13.9, 13.7; ³¹P NMR (120 MHz,

CDCl₃): −2.44 (s, 1P); ESI FT-MS: m/z (M+Na)⁺

calcd 710.2548, obsd 710.2539.

3,4-Di-O-benzyl-2-benzyloxycarbonylamino-2-deoxy-

6-O-le6ulinyl-h,i-D-glucopyranose, 1-dibutylphosphate

(18).—n-Pentenyl glycoside M (27 mg, 41.5 mmol) was

azeotroped with toluene (3×5 mL) and dried under

vacuum for 1 h. CH₂Cl₂(1.0 mL) was added followed

n-Pentenyl

6-O-acetyl-3,4-di-O-benzyl-2-deoxy-2-

(2,2,2-trichloroethoxycarbonylamino)-i-D-glucopyranos-

ide (N).—To a stirred solution of G (3.26 g, 8.09 mmol)

in Et₂O (40 mL) and satd aq NaHCO₃(40 mL) was

added 2,2,2-trichloroethyl chloroformate (1.65 g, 9.71

mmol). After 1 h, the solution was diluted with ether

(60 mL), washed with satd NaHCO₃(3×50 mL), H₂O,

brine, dried over Na₂SO₄, ﬁltered, and concentrated in

vacuo. Puriﬁcation by ﬂash silica gel chromatography

,

by ﬂame-dried 4 A molecular sieves (50 mg), dibutyl

phosphate (18 mg, 83.0 mmol) and NBS (15 mg, 41.0

mmol). The reaction mixture was shielded from light

and stirred for 14 h, diluted with ether (10 mL), and

washed with satd Na₂S₂O₃(5×5 mL). The aqueous

layer was extracted with ether (10 mL), and the com-

bined organic phases were washed with brine and dried

over Na₂SO₄. After ﬁltration and concentration in

vacuo, the crude product was puriﬁed by ﬂash silica gel

chromatography (1:1 EtOAc–hexanes) to afford 14 mg

(45%, a:b=1:1) of 18 as a white solid. IR (thin ﬁlm):

(1:4 EtOAc–hexanes) yielded 4.38

n-pentenyl 3,4-di-O-benzyl-2-deoxy-2-(2,2,2-trichloro-

ethoxycarbonylamino)-b- -glucopyranoside as a white

solid. [h]_D+0.66° (c 0.91, CH₂Cl₂); IR (thin ﬁlm):

3319, 1709, 1548, 1071 cm^{−1 1}H NMR (400 MHz,

CDCl₃) 7.42–7.27 (m, 10H), 5.87–5.69 (m,

g

(90%) of

D

;

3291, 1717, 1540, 1260, 1026 cm⁻¹

;

¹H NMR (500

l

1906

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

1H), 5.11 (br s, 1H), 5.06–4.93 (m, 2H), 4.87 (d, J 11.0

Hz, 1H), 4.86 (d, J 11.2 Hz, 1H), 4.78–4.60 (m, 5H),

3.95 (br s, 1H), 3.93–3.82 (m, 2H), 3.76 (br s, 1H), 3.63

(dd, J 8.9, 9.4 Hz, 1H), 3.48 (td, J 6.8, 9.6 Hz, 1H),

3.46–3.39 (m, 1H), 3.38–3.27 (m, 1H), 2.18–2.05 (m,

2H), 1.96 (br s, 1H), 1.76–1.57 (m, 2H); ¹³C NMR (100

MHz, CDCl₃) l 154.2, 138.2, 138.1, 138.0, 128.8, 128.7,

128.3, 128.1, 115.2, 100.7, 95.7, 80.6, 78.6, 77.4, 75.4,

75.2, 75.1, 74.6, 69.6, 62.1, 58.3, 30.2, 28.9; ESI FT-MS:

m/z (M+Na)⁺calcd 624.1299, obsd 624.1289.

11.5 Hz, 1H), 4.92 (d, J 10.9 Hz, 1H), 4.78 (d, J 11.5

Hz, 1H), 4.76 (d, J 12.0 Hz, 1H), 4.66 (d, J 12.0 Hz,

1H), 4.65 (d, J 10.9 Hz, 1H), 4.60 (d, J 8.9 Hz, 1H),

4.33 (dd, J 2.2, 12.2 Hz, 1H), 4.26 (dd, J 3.7, 12.2 Hz,

1H), 4.11 (ddd, J 3.5, 9.1, 10.6 Hz, 1H), 4.03–3.95 (m,

1H), 3.86 (dd, J 9.0, 10.5 Hz, 1H), 3.75 (dd, J 9.3, 9.7

Hz, 1H), 2.05 (s, 3H); ¹³C NMR (100 MHz, CDCl₃) l:

170.7, 160.5, 154.3, 137.5, 137.3, 129.0, 128.9, 128.8,

128.6, 128.5, 128.2, 95.6, 95.4, 91.0, 79.3, 78.1, 77.4,

75.5, 75.2, 74.8, 54.6, 20.9; ESI FT-MS: m/z (M+

Na)⁺calcd 740.9668, obsd 740.9862.

To a stirred solution of n-pentenyl 3,4-di-O-benzyl-2-

deoxy - 2 - (2,2,2 - trichloroethoxycarbonylamino) - b - D-

n-Pentenyl

2-deoxy-2-trichloroacetylamino-i-D-

glucopyranoside (P).—To a stirred solution of O (5.90

g, 12.1 mmol) in CH₂Cl₂(120 mL) at 0 °C, was added

BF₃·Et₂O (4.43 g, 31.3 mmol) and 4-penten-1-ol (1.14 g,

13.3 mmol). The reaction mixture was warmed to ambi-

ent temperature, then stirred for 48 h, diluted with

CH₂Cl₂(100 mL), and washed with satd NaHCO₃

(3×100 mL). The aqueous layer was extracted with

CH₂Cl₂(100 mL), and the combined organic phases

were washed with brine and dried over Na₂SO₄. After

ﬁltration and concentration in vacuo, the crude product

was puriﬁed by ﬂash silica gel chromatography (2:3

EtOAc–hexanes) to afford 4.94 g (79%) of n-pentenyl

glucopyranoside (4.38 g, 7.28 mmol) in CH₂Cl₂(60 mL)

and pyridine (20 mL) was added DMAP (89 mg, 0.73

mmol) and Ac₂O (1.48 g, 14.6 mmol). After 2 h, the

reaction mixture was diluted with CH₂Cl₂(60 mL),

washed with HCl (10% aq, 5×50 mL), H₂O, brine,

dried over Na₂SO₄, ﬁltered, and concentrated in vacuo.

Puriﬁcation by ﬂash silica gel chromatography (1:4

EtOAc–hexanes) afforded 4.31 g (92%) of N as a

yellow solid. [h]_D+7.46° (c 0.93, CH₂Cl₂); IR (thin

ﬁlm): 3362, 1730, 1715, 1533, 1249 cm^{−1 1}H NMR

;

(500 MHz, CDCl₃) l 7.39–7.27 (m, 10H), 5.83–5.73

(m, 1H), 5.20 (br s, 1H), 5.02 (ddd, J 1.8, 3.7, 17.1 Hz,

1H), 4.96 (ddd, J 1.2, 2.1, 10.4 Hz, 1H), 4.86 (d, J 11.0

Hz, 1H), 4.84 (d, J 11.3 Hz, 1H), 4.75 (d, J 11.3 Hz,

1H), 4.71 (bs, 1H), 4.65 (bs, 1H), 4.59 (d, J 11.0 Hz,

1H), 4.36 (d, J 11.3 Hz, 1H), 4.25 (dd, J 4.6, 11.9 Hz,

1H), 3.99 (bs, 1H), 3.87 (td, J 6.4, 9.5 Hz, 1H), 3.62–

3.55 (m, 2H), 3.47 (td, J 7.0, 9.8 Hz, 1H), 3.42–3.31 (m,

1H), 2.15–2.07 (m, 2H), 2.06 (s, 3H), 1.73–1.59 (m,

2H); ¹³C NMR (125 MHz, CDCl₃) l 170.9, 154.1,

138.2, 138.0, 137.7, 128.8, 128.7, 128.3, 128.2, 128.1,

115.2, 100.4, 95.6, 80.8, 78.5, 75.2, 75.1, 74.6, 73.0, 69.5,

63.3, 58.1, 30.2, 28.8, 21.1; ESI FT-MS: m/z (M+

Na)⁺calcd 666.1416, obsd 666.1391.

3,4,6-tri-O-acetyl-2-deoxy-2-trichloroacetylamino-b-D-

glucopyranoside as a white solid. [h]_D+74.7° (c 0.99,

CH₂Cl₂); IR (thin ﬁlm): 3320, 1749, 1519, 1227, 1042

cm⁻¹; ¹H NMR (400 MHz, CDCl₃) l 6.92 (d, J 9.2 Hz,

1H), 5.84–5.72 (m, 1H), 5.32 (dd, J 9.8, 10.4 Hz, 1H),

5.14 (dd, J 9.5, 10.1 Hz, 1H), 5.06–4.97 (m, 2H), 4.93

(d, J 3.7 Hz, 1H), 4.29–4.20 (m, 2H), 4.13–4.06 (m,

1H), 3.98 (ddd, J 2.4, 4.6, 10.1 Hz, 1H), 3.74 (td, J 6.4,

16.2 Hz, 1H), 3.48 (td, J 6.4, 12.8 Hz, 1H), 2.16–2.10

(m, 2H), 2.09 (s, 3H), 2.03 (s, 3H), 2.01 (s, 3H),

1.75–1.68 (m, 2H); ¹³C NMR (125 MHz, CDCl₃) l

171.3, 170.8, 169.5, 161.9, 137.5, 115.7, 96.5, 92.2, 71.0,

68.2, 68.1, 61.9, 54.1, 54.0, 30.3, 28.5, 21.0, 20.8; ESI

FT-MS: m/z (M+Na)⁺calcd 540.0565, obsd 540.0540.

To a stirred solution of n-pentenyl 3,4,6-tri-O-acetyl-

6-O-Acetyl-3,4-di-O-benzyl-2-deoxy-2-(2,2,2-tri-

chloroethoxycarbonylamino)-h-D-glucopyranosyl

tri-

choroacetimidate (22).—To a stirred solution of N (1.26

g, 1.96 mmol) in CH₃CN (10.0 mL) and H₂O (0.1 mL)

was added NBS (0.69 g, 3.91 mmol). After 14 h

shielded from light, the reaction was diluted with ether

(20 mL), washed with satd sodium thiosulfate (5×20

mL), H₂O, brine, dried over Na₂SO₄, ﬁltered, and

concentrated in vacuo. The crude product was

azeotroped with toluene (3×5 mL), dried under vac-

uum for 1 h, and dissolved in CH₂Cl₂(15 mL). After

cooling to 0 °C, trichloroacetonitrile (5.08 g, 35.0

mmol) and DBU (119 mg, 0.79 mmol) were added, and

the reaction mixture was stirred for 2 h. The solution

was concentrated in vacuo, and puriﬁed by ﬂash silica

gel chromatography (2:3 EtOAc–hexanes) to yield 922

mg (66%) of 22 as a white solid. [h]_D+63.2° (c 1.05,

CH₂Cl₂); IR (thin ﬁlm): 3340, 1740, 1675, 1516, 1239

2-deoxy-2-trichloroacetylamino-b-D-glucopyranoside

(3.86 g, 7.46 mmol) in MeOH (80 mL), was added

NaOMe (161 mL, 0.75 mmol, 25% w/v in MeOH). After

14 h, the reaction was quenched by the addition of

strongly acidic ion-exchange resin until the pH of the

solution reached 5–6, and the solution was ﬁltered and

concentrated in vacuo. Puriﬁcation by ﬂash silica gel

chromatography (3:2 EtOAc–hexanes) afforded 2.55 g

(87%) of P as an orange solid. [h]_D+72.8° (c 0.94,

CH₂Cl₂); IR (thin ﬁlm): 3335, 1699, 1521, 1034 cm⁻¹

;

¹H NMR (500 MHz, CD₃OD) l 8.21 (d, J 6.7 Hz, 1H),

5.83–5.75 (m, 1H), 4.98 (d, J 17.1 Hz, 1H), 4.92 (d, J

10.4 Hz, 1H), 3.84–3.77 (m, 3H), 3.76–3.69 (m, 2H),

3.68–3.66 (m, 1H), 3.61–3.56 (m, 2H), 3.42–3.33 (m,

3H), 2.16–2.11 (m, 2H), 1.69–1.63 (m, 2H); ¹³C NMR

(100 MHz, CD₃OD) l 164.3, 139.4, 115.3, 97.8, 93.9,

70.1, 68.8, 62.6, 57.8, 31.5, 31.4, 30.1, 29.9; ESI FT-MS:

m/z (M+Na)⁺calcd 414.0248, obsd 414.0247.

1

cm⁻¹; H NMR (400 MHz, CDCl₃) l: 8.69 (s, 1H),

7.46–7.28 (m, 10H), 6.32 (d, J 3.4 Hz, 1H), 4.96 (d, J

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

1907

n-Pentenyl 3,4-di-O-acetyl-2-deoxy-2-trichloroacetyl-

amino-6-O-triisopropylsilyl-i-D-glucopyranoside (Q).—

To a stirred solution of P (2.48 g, 6.34 mmol) in DMF

(60 mL) at 0 °C, was added imidazole (0.86 g, 12.6

mmol) and triisopropylchlorosilane (1.46 g, 7.61 mmol).

The reaction mixture was allowed to warm to ambient

temperature over 16 h, then water (100 mL) was added.

The aqueous layer was extracted with ether (3×100

mL), and the combined organic phases were washed

with brine and dried over Na₂SO₄. After ﬁltration and

concentration in vacuo, the crude product was puriﬁed

by ﬂash silica gel chromatography (1:1 EtOAc–hex-

anes) to afford 2.84 g (82%) of n-pentenyl 2-deoxy-2-

phases were washed with brine, dried over Na₂SO₄,

ﬁltered, and concentrated in vacuo. Puriﬁcation by

ﬂash silica gel chromatography (2:3 EtOAc–hexanes)

afforded 2.00 g (83%) of n-pentenyl 3,4-di-O-acetyl-2-

deoxy-2-trichloroacetylamino-b-

white solid. [h]_D−47.3° (c 1.00, CH₂Cl₂); IR (thin

ﬁlm): 2226, 1716, 1695, 1532, 1233 cm⁻^{1 1}H NMR

D-glucopyranoside as a

;

(500 MHz, CDCl₃) l 7.24 (d, J 8.9 Hz, 1H), 5.80–5.71

(m, 1H), 5.35 (dd, J 8.9, 10.7 Hz, 1H), 5.02–4.92 (m,

2H), 4.63 (d, J 8.2 Hz, 1H), 4.45 (dd, J 4.3, 12.2 Hz,

1H), 4.34 (dd, J 1.2, 11.9 Hz, 1H), 3.97–2.36 (m, 2H),

3.64–3.56 (m, 2H), 3.51–3.45 (m, 1H), 3.43 (d, J 5.2

Hz, 1H), 2.13 (s, 3H), 2.10 (s, 3H), 2.09–2.01 (m, 2H),

1.72–1.58 (m, 2H); ¹³C NMR (125 MHz, CDCl₃) l

172.3, 172.1, 162.4, 138.0, 115.2, 100.8, 92.6, 74.4, 74.1,

69.6, 63.3, 56.1, 30.1, 28.8, 21.1; ESI FT-MS: m/z

(M+Na)⁺calcd, 498.0465, obsd 498.0456.

trichloroacetylamino-6-O-triisopropylsilyl-b-D-glucopyra

noside as a white solid. [h]_D+53.3° (c 0.98, CH₂Cl₂);

1

IR (thin ﬁlm): 3419, 1716, 1516, 1057 cm⁻¹; H NMR

(500 MHz, CDCl₃) l 7.00 (d, J 8.5 Hz, 1H), 5.82–5.72

(m, 1H), 5.04–4.95 (m, 2H), 4.86 (d, J 3.7 Hz, 1H), 3.99

(dt, J 3.7, 8.6 Hz, 1H), 3.93 (d, J 5.2 Hz, 2H), 3.86–

3.78 (m, 2H), 3.73 (td, J 6.4, 9.8 Hz, 1H), 3.68 (td, J

5.5, 9.5 Hz, 1H), 3.62–3.56 (m, 1H), 3.47–3.44 (m, 1H),

3.42 (td, J 7.7, 9.8 Hz, 1H), 2.16–2.08 (m, 2H), 1.73–

1.64 (m, 2H), 1.21–0.98 (m, 21H); ¹³C NMR (125

MHz, CDCl₃) l 162.7, 137.8, 115.4, 96.5, 92.6, 73.7,

72.9, 70.9, 67.4, 65.0, 55.2, 30.4, 28.7, 18.1, 11.9; ESI

FT-MS: m/z (M+Na)⁺calcd 570.1583, obsd 570.1587.

To a stirred solution of n-pentenyl 2-deoxy-2-

To a stirred solution of n-pentenyl 3,4-di-O-acetyl-2-

deoxy-2-trichloroacetylamino-b-D-glucopyranoside (2.0

g, 4.2 mmol) in CH₂Cl₂(40 mL) and pyridine (10 mL)

was added DMAP (51 mg, 0.42 mmol) and levulinic

anhydride (1.38 g, 6.45 mmol). After 2 h in the dark,

the reaction mixture was diluted with CH₂Cl₂(60 mL),

washed with HCl (10% aq solution, 3×100 mL), H₂O

(100 mL), brine (50 mL), dried over Na₂SO₄, ﬁltered,

and concentrated in vacuo. Puriﬁcation by ﬂash silica

gel chromatography (2:3 EtOAc–hexanes) yielded 2.13

g (88%) of R as a white solid. [h]_D−8.37° (c 0.90,

CH₂Cl₂); IR (thin ﬁlm): 3337, 1749, 1717, 1532, 1229

cm⁻¹; ¹H NMR (500 MHz, CDCl₃) l 7.01 (d, J 8.5 Hz,

1H), 5.79–5.69 (m, 1H), 5.40 (dd, J 10.3, 10.7 Hz, 1H),

5.14 (dd, J 9.7, 9.8 Hz, 1H), 4.98 (dd, J 1.5, 17.4 Hz,

1H), 4.93 (d, J 10.1 Hz, 1H), 4.67 (d, J 8.2 Hz, 1H),

4.28 (dd, J 4.9, 12.5 Hz, 1H), 4.14 (dd, J 2.1, 12.5 Hz,

1H), 3.98 (td, J 8.5, 10.7 Hz, 1H), 3.88 (td, J 6.1, 9.8

Hz, 1H), 3.75 (ddd, J 2.1, 4.9, 10.1 Hz, 1H), 3.47 (td, J

6.7, 9.5 Hz, 1H), 2.85–2.76 (m, 1H), 2.72–2.62 (m, 1H),

2.55–2.40 (m, 2H), 2.18 (s, 3H), 2.11–2.00 (m, 2H),

2.07 (s, 6H), 1.72–1.56 (m, 2H); ¹³C NMR (100 MHz,

CDCl₃) l 206.2, 171.6, 171.4, 170.9, 162.2, 137.9, 115.2,

100.8, 92.5, 72.2, 71.6, 69.6, 68.5, 62.2, 56.1, 37.9, 30.0,

29.8, 27.9, 21.0, 20.8; ESI FT-MS: m/z (M+Na)⁺

calcd 596.0833, obsd 596.0821.

trichloroacetylamino-6-O-triisopropylsilyl-b-D-glucopy-

ranoside (2.84 g, 5.19 mmol) in CH₂Cl₂(30 mL) and

pyridine (10 mL) was added DMAP (63 mg, 0.52

mmol) and Ac₂O (1.66 g, 20.8 mmol). After 3 h, the

solution was diluted with CH₂Cl₂(70 mL), washed with

HCl (10% aq solution, 3×100 mL), H₂O (100 mL),

brine (50 mL), dried over Na₂SO₄, ﬁltered, and concen-

trated in vacuo. Puriﬁcation by ﬂash silica gel chro-

matography 3:7 EtOAc–hexanes) yielded 3.18 g (96%)

of Q as a white solid. [h]_D+76.5° (c 1.09, CH₂Cl₂); IR

(thin ﬁlm): 3425, 1753, 1724, 1515, 1238 cm⁻^{1 1}H

;

NMR (500 MHz, CDCl₃) l 6.93 (d, J 9.2 Hz, 1H),

5.83–5.73 (m, 1H), 5.31 (dd, J 9.9, 10.4 Hz, 1H), 5.06

(t, J 9.8 Hz, 1H), 5.04–4.95 (m, 2H), 4.90 (d, J 3.9 Hz,

1H), 4.19 (ddt, J 0.9, 3.7, 9.5 Hz, 1H), 3.84 (ddd, J 2.8,

4.9, 10.1 Hz, 1H), 3.80–3.70 (m, 3H), 3.45 (td, J 6.4,

9.8 Hz, 1H), 2.15–2.10 (m, 1H), 2.02 (s, 3H), 2.00 (s,

3H), 1.12–0.92 (m, 21H); ¹³C NMR (125 MHz, CDCl₃)

l 171.4, 169.5, 161.9, 137.7, 115.5, 96.2, 71.4, 71.2, 68.7,

67.6, 62.8, 54.1, 30.4, 28.6, 20.9, 20.8, 18.0, 17.9, 12.0;

ES1 FT-MS: m/z (M+Na)⁺calcd 654.1794, obsd

654.1793.

3,4-Di-O-acetyl-2-deoxy-6-O-le6ulinyl-2-trichloro-

acetylamino-h-D-glucopyranosyl

trichloroacetimidate

(24).—To a stirred solution of R (2.2 g, 3.8 mmol) in

CH₃CN (40 mL) and H₂O (4 mL) was added NBS (1.36

g, 7.66 mmol). After 13 h shielded from light, the

solution was diluted with ether (100 mL) and washed

with satd Na₂S₂O₃(5×100 mL). The aqueous layer

was extracted with ether (100 mL), and the combined

organic phases were washed with brine, dried over

Na₂SO₄, and concentrated in vacuo to afford the crude

n-Pentenyl 3,4-di-O-acetyl-2-deoxy-6-O-le6ulinyl-2-

trichloroacetylamino-i-D-glucopyranoside (R).—To

a

stirred solution of Q (3.18 g, 5.03 mmol) in THF (30

mL) was added AcOH (453 mL, 7.54 mmol) and TBAF

(7.5 mL, 7.5 mmol, 1 M in THF). After 12 h, NaHCO₃

(50 mL) was added, and the aqueous layer was ex-

tracted with ether (3×100 mL). The combined organic

lactol as

a yellow oil. The crude product was

azeotroped with toluene (3×10 mL), dried under vac-

uum for 1 h, and dissolved in CH₂Cl₂(40 mL). After

1908

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

cooling to 0 °C, trichloroacetonitrile (5.51 g, 38.3

mmol) and DBU (123 mg, 1.15 mmol) were added, and

the reaction mixture was stirred for 2 h. The solution

was concentrated in vacuo and puriﬁed by ﬂash silica

gel chromatography (2:3 EtOAc–hexanes) to afford

1.99 g (80 %) of 24 as a white foam. [h]_D+72.0° (c

0.98, CH₂Cl₂); IR (thin ﬁlm): 3315, 1749, 1718, 1683,

(thin ﬁlm): 3503, 3329, 2929, 1692, 1529 cm⁻^{1 1}H

;

NMR (400 MHz, CDCl₃) l 7.38–7.27 (m, 10H), 6.94

(d, J 7.9 Hz, 1H), 5.13 (d, J 7.8 Hz, 1H), 4.85 (d, J 11.1

Hz, 1H), 4.84 (d, J 10.8 Hz, 1H), 4.73 (d, J 10.8 Hz,

1H), 4.69 (d, J 11.1 Hz, 1H), 4.15 (dd, J 8.6, 10.2 Hz,

1H), 3.87 (dd, J 2.8, 11.9 Hz, 1H), 3.74 (dd, J 4.6, 11.9

Hz, 1H), 3.64 (app t, J 9.3 Hz, 1H), 3.55–3.48 (m, 2H),

1.83 (br s, 1H), 0.90 (s, 9H), 0.13 (s, 3H), 0.11 (s, 3H);

¹³C NMR (100 MHz, CDCl₃) l 161.9, 138.0, 137.9,

128.7, 128.7, 128.2, 128.1, 94.6, 92.7, 79.7, 78.6, 75.4,

75.2, 75.0, 62.2, 60.9, 25.8, 18.0, −3.9, −4.9; ESI

FT-MS: m/z (M+Na)⁺calcd 640.1432, obsd 640.1424.

3,4-Di-O-benzyl- 2-deoxy-6-O-le6ulinyl-2-trichloro-

1

1519 cm⁻¹; H NMR (500 MHz, CDCl₃) l 8.84 (s,

1H), 7.00 (d, J 8.6 Hz, 1H), 6.48 (d, J 3.7 Hz, 1H), 5.43

(dd, J 9.8, 11.0 Hz, 1H), 5.27 (dd, J 10.1, 10.2 Hz, 1H),

4.44 (ddd, J 3.4, 8.6, 10.7 Hz, 1H), 4.27 (dd, J 4.6, 12.5

Hz, 1H), 4.20–4.10 (m, 2H), 2.82–2.68 (m, 2H), 2.66–

2.32 (m, 2H), 2.19 (s, 3H), 2.07 (s, 3H), 2.06 (s, 3H); ¹³

C

NMR (125 MHz, CDCl₃) l 206.5, 172.5, 171.7, 169.3,

162.2, 160.1, 93.8, 91.9, 90.7, 70.7, 70.3, 67.1, 61.7, 54.0,

38.0, 29.8, 30.0, 29.8, 28.0, 20.8; ESI FT-MS: m/z

(M+Na)⁺calcd 670.9304, obsd 670.9297.

acetylamino-h-D-glucopyranosyl

trichloroacetimidate

(U).—To a stirred solution of T (0.687 g, 1.11 mmol) in

CH₂Cl₂(10 mL) at 0 °C was added, levulinic acid (0.12

mL, 1.17 mmol) and DMAP (0.149 g, 1.22 mmol).

After 5 min, DIPC (0.17 mL, 1.11 mmol) was added,

and the solution was left to slowly warm to room

temperature. After 6 h, the reaction mixture was con-

centrated in vacuo, and the residue was puriﬁed by

ﬂash silica gel chromatography (10:9025:75 EtOAc–

hexanes) yielding 0.756 g (95%) of tert-butyldimethylsi-

lyl 3,4-di-O-benzyl-2-deoxy-6-O-levulinyl-2-trichloro-

tert-Butyldimethylsilyl

trichloroacetylamino-h-D-glucopyranoside (T).—To

stirred solution of S (1.03 g, 2.01 mmol) in CH₂Cl₂(10

3,4-di-O-benzyl-2-deoxy-2-

a

,

mL) were added activated 4 A molecular sieves (1 g),

benzyl bromide (0.60 mL, 5.02 mmol), and Ag₂O (1.40

g, 6.03 mmol). The ﬂask was shielded from light, and

the solution was stirred for 2 h. The solution was

ﬁltered through a pad of silica gel, and the ﬁltrate was

concentrated in vacuo. The resulting residue was

puriﬁed by ﬂash silica gel chromatography (5:95

10:90 EtOAc–hexanes) to yield 1.01 g (82%) of tert-

acetylamino-a-D-glucopyranoside as a clear oil. [h]_D

+0.8° (c 0.76, CH₂Cl₂); IR (thin ﬁlm): 3333, 2928,

1739, 1718, 1695 cm⁻¹; H NMR (400 MHz, CDCl₃) l

7.37–7.29 (m, 10H), 6.94 (d, J 7.9 Hz, 1H), 5.07 (d, J

7.5 Hz, 1H), 4.84 (d, J 11.2 Hz, 1H), 4.81 (d, J 11.9 Hz,

1H), 4.73 (d, J 11.0 Hz, 1H), 4.62 (d, J 11.0 Hz, 1H),

4.40 (dd, J 2.5, 11.7 Hz, 1H), 4.21 (dd, J 5.9, 11.7 Hz,

1H), 4.13 (dd, J 8.2, 10.0 Hz, 1H), 3.68–3.64 (m, 1H),

3.58–3.51 (m, 1H), 2.75 (app t, J 6.5 Hz, 1H), 2.59 (td,

J 0.8, 6.5 Hz, 1H), 2.20 (s, 3H), 0.88, (s, 9H), 0.12 (s,

3H), 0.10 (s, 3H); ¹³C NMR (100 MHz, CDCl₃) l

206.6, 172.6, 161.9, 137.9, 137.6, 128.9, 128.2, 128.2,

128.1, 128.1, 94.5, 92.7, 79.8, 78.6, 77.4, 75.1, 74.9, 73.2,

63.5, 60.4, 38.1, 30.1, 30.0, 28.0, 25.8, 18.1, −4.0,

−5.0; ESI FT-MS: m/z (M+Na)⁺calcd 738.1794,

obsd 738.1768.

butyldimethylsilyl

deoxy-2-trichloroacetylamino-a-

white solid. [h]_D−21.0° (c 0.64, CH₂Cl₂); IR (thin

ﬁlm): 3321, 2929, 2857, 1692, 1085 cm^{−1 1}H NMR

3-O-benzyl-4,6-O-benzylidene-2-

D-glucopyranoside as a

;

(400 MHz, CDCl₃) l 7.52–7.49 (m, 2H), 7.43–7.38 (m,

3H), 7.31–7.28 (m, 5H), 6.87 (d, J 8.7 Hz, 1H), 5.60 (s,

1H), 5.18 (d, J 7.9 Hz, 1H), 4.91 (d, J 11.2 Hz, 1H),

4.70 (d, J 11.2, 1H), 4.33 (dd, J 5.0, 10.5 Hz, 1H), 4.25

(dd, J 9.0, 10.2 Hz, 1H), 3.83 (t, J 10.3 Hz, 1H), 3.77 (t,

J 9.2 Hz, 1H), 3.58–3.47 (m, 2H), 0.89 (s, 9H), 0.12 (s,

3H), 0.11 (s, 3H); ¹³C NMR (100 MHz, CDCl₃) l

161.9, 138.1, 137.4, 129.3, 128.6, 128.5, 128.1, 126.2,

101.5, 995.2, 83.0, 75.8, 74.9, 68.9, 66.4, 61.2, 25.8, 18.0,

−4.0, −5.0; ESI FT-MS: m/z (M+Na)⁺calcd

638.1270, obsd 638.1250.

To a stirred solution of tert-butyldimethylsilyl 3,4-

di-O-benzyl-2-deoxy-6-O-levulinyl-2-trichloroacetyl-

amino-a-D-glucopyranoside (0.745 g, 1.04 mmol) in

A solution of BH₃(1.0 M in THF, 14.0 mL) was

added tert-butyldimethylsilyl 3-O-benzyl-4,6-O-benzyli-

dene-2-deoxy-2-trichloroacetylamino-a-D-glucopyran-

THF (10 mL) at 0 °C were added dropwise and simul-

taneously TBAF (1.56 mL of a 1.0 M solution in THF)

and HOAc (90 mL, 1.56 mmol). After 4 h, the reaction

mixture was diluted with water (50 mL) and extracted

with EtOAc (2×100 mL). Combined organic extracts

were washed with water and satd aq NaHCO₃(100 mL

each), dried over Na₂SO₄, ﬁltered and concentrated in

vacuo. Residue was dissolved in a solution of CH₂Cl₂

(10 mL), and CCl₃CN (2 mL) and DBU (29 mL, 0.196

mmol) added. After 90 min, the reaction mixture was

concentrated in vacuo. The resulting brown residue was

puriﬁed by ﬂash silica gel chromatography (25:75

40:60 EtOAc–hexanes) to yield 0.609 g (78% over two

oside (0.89 g, 1.40 mmol) at 0 °C. After 5 min, a

solution of Bu₂BOTf (1.0 M in CH₂Cl₂, 1.68 mL) was

added. After 1 h, the reaction was quenched by addi-

tion of TEA (1.50 mL), and methanol was then slowly

added until the evolution of gas had ceased. The solu-

tion was concentrated, and the resulting residue was

azeotroped with methanol (3×10 mL). The residue

was then puriﬁed by ﬂash silica gel chromatography

(10:9025:75 EtOAc–hexanes) affording 0.68 g (80%)

of T as a white foam. [h]_D−6.2° (c 3.19, CH₂Cl₂); IR

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

1909

steps) of imidate U as white foam. [h]_D+32.6° (c 0.76,

CH₂Cl₂); IR (thin ﬁlm): 3411, 3345, 2917, 1716, 1070

of glucosamine phosphate (1.3 equiv) and acceptor 1

(1.0 equiv) was coevaporated with toluene, dried under

vacuum for 2 h, and dissolved in CH₂Cl₂. The solution

was cooled to −15 °C, and TMSOTf (1.3 equiv, 1.0 M

in CH₂Cl₂) was added. Et₃N was added to quench the

reaction, the solution was concentrated in vacuo, and

the crude product was puriﬁed by ﬂash silica gel chro-

matography (1:4 EtOAc–hexanes) to afford the desired

disaccharide.

1

cm⁻¹; H NMR (400 MHz, CDCl₃) l 8.74 (s, 1H),

7.39–7.30 (m, 10H), 6.54 (d, J 8.6 Hz, 1H), 6.39 (d, J

3.5 Hz, 1H), 4.91 (d, J 11.2 Hz, 1H), 4.90 (d, J 10.6 Hz,

1H), 4.82 (d, J 11.2 Hz, 1H), 4.66 (d, J 10.6 Hz, 1H),

4.42–4.31 (m, 3H), 4.05–4.02 (m, 1H), 3.98 (dd, J 8.9,

10.5 Hz, 1H), 3.81 (app t, J 9.6 Hz, 1H), 2.82–2.74 (m,

2H), 2.63–2.58 (m, 2H), 2.20 (s, 3H); ¹³C NMR (100

MHz, CDCl₃) l 207.3, 206.7, 172.7, 172.6, 163.6, 163.2,

137.4, 129.0, 128.9, 128.8, 128.6, 128.4, 128.4, 128.3,

128.2, 128.2, 128.2, 104.3, 95.0, 79.3, 78.3, 77.4, 75.5,

74.9, 74.8, 74.6, 71.9, 70.0, 65.9, 63.2, 38.1, 38.0, 30.1,

28.1, 28.0; ESI FT-MS: m/z (M+Na)⁺calcd 767.0026,

obsd 767.0012.

3,4-Di-O-benzyl-2-deoxy-2-phthalimido-6-O-triiso-

propylsilyl - i - ^{D -}glucopyranosyl - (16) - 1,2:3,4 - di - O-

isopropylidene-h-^D-galactopyranose (3).—Coupling of 2

(97 mg, 0.122 mmol) and 1 (25 mg, 94 mmol) following

general procedure A at −20 °C using TMSOTf (25 mL,

12.5 mmol, 0.5 M in CH₂Cl₂) for 1 h, afforded 76 mg

(70%) of 3 as a white solid. [h]_D−8.2° (c 0.86,

3,4-Di-O-benzyl-2-deoxy- 6-O-le6ulinyl-2-trichloro-

acetylamino-h-^D-glucopyranose,

1-dibutylphosphate

CH₂Cl₂); IR (thin ﬁlm): 1777, 1716, 1387, 1071 cm⁻¹

;

(26).—To a solution of U (592 mg, 0.79 mmol) in

toluene (10 mL) at 0 °C was added dibutylphosphate

(0.19 mL, 0.95 mmol). The solution was left to slowly

warm to room temperature and after 90 min was

concentrated in vacuo. The resulting residue was

puriﬁed by ﬂash silica gel chromatography (25:70

40:60 EtOAc–hexanes) affording 26 (561 mg, 89%) as a

yellow oil. [h]_D−30.6° (c 6.56, CH₂Cl₂); IR (thin ﬁlm):

¹H NMR (500 MHz, CDC1₃) l 7.81–7.60 (m, 4H),

7.37–7.34 (m, 4H), 7.32–7.28 (m, 1H), 7.03–6.99 (m,

2H), 6.92–6.83 (m, 3H), 5.19 (d, J 8.5 Hz, 1H), 5.15 (d,

J 4.9 Hz, 1H), 4.87 (d, J 10.7 Hz, 1H), 4.83 (d, J 11.0

Hz, 1H), 4.80 (d, J 12.2 Hz, 1H), 4.47 (d, J 11.9 Hz,

1H), 4.41 (dd, J 8.5, 10.7 Hz, 1H), 4.08 (dd, J 2.4, 5.2

Hz, 1H), 4.05–4.01 (m, 2H), 3.95 (dd, J 1.2, 7.9 Hz,

1H), 3.88–3.80 (m, 2H), 3.64–3.58 (m, 2H), 3.49 (td, J

2.8, 9.8 Hz, 1H), 1.38 (s, 3H), 1.21 (s, 3H), 1.19–1.06

(m, 21H), 1.01 (s, 3H), 0.98 (s, 3H); ¹³C NMR (125

MHz, CDCl₃) l 168.3, 163.6, 138.5, 138.3, 133.4, 128.7,

128.2, 128.1, 128.0, 127.9, 127.5, 123.2, 109.3, 108.1,

99.1, 96.1, 79.4, 79.2, 77.4, 75.9, 75.0, 71.0, 70.7, 70.3,

68.3, 67.5, 62.4, 56.2, 26.0, 25.4, 24.8, 24.3, 18.2, 12.2;

ESI FT-MS: m/z (M+Na)⁺calcd 910.4173, obsd

910.4145.

3415, 3337, 3032, 2961, 1717 cm^{−1 1}H NMR (400

;

MHz, CDCl₃) l 7.37–7.28 (m, 10H), 6.93 (d, J 9.4 Hz,

1H), 5.47 (app t, J 7.9 Hz, 1H), 4.83 (app d, J 9.7 Hz,

2H), 4.77 (d, J 10.8 Hz, 1H), 4.58 (d, J 10.9 Hz, 1H),

4.40 (dd, J 2.2, 12.0 Hz, 1H), 4.26 (dd, J 5.1, 11.9 Hz,

1H), 4.18–3.96 (m, 8H), 3.73–3.68 (m, 1H), 3.63 (app t,

J 8.3 Hz, 1H), 2.84–2.73 (m, 2H), 2.63–2.54 (m, 2H),

2.20 (s, 3H), 1.70–1.64 (m, 4H), 1.44–1.34 (m, 4H),

0.94 (t, J 7.4 Hz, 3H), 0.93 (t, J 7.4 Hz, 3H); ¹³C NMR

(100 MHz, CDCl₃) l 207.6, 206.5, 172.6 (d, J 4.3 Hz),

162.2, 161.9, 137.8 (d, J 7.3 Hz), 137.5, 128.8, 128.8,

128.7, 128.3, 128.2, 128.1, 128.1, 92.7, 92.3, 91.4, 80.1,

79.0, 78.2, 77.4, 75.6, 75.4, 75.2, 71.5, 69.3, 68.5, 63.1,

62.3, 55.2, 54.9, 38.3, 38.0, 32.4, 30.0 (d, J 3.7 Hz), 28.2,

27.9 (d, J =10.0 Hz), 18.8, 13.8; ³¹P (120 MHz,

CDCl₃) l −3.13; ESI FT-MS: m/z (M+Na)⁺calcd

816.1845, obsd 816.1833.

3,4 - Di - O - acetyl - 6 - O - 2 - (azidomethyl)benzoyl)-2-

deoxy-2-phthalimido-i-D - glucopyranosyl-(16)-1,2:

3,4-di-O-isopropylidene-h-D-galactopyranose

(7).—

Coupling of 6 (86 mg, 0.12 mmol) and 1 (27 mg, 0.10

mmol) following general procedure A for 1 h at 0 °C

using TMSOTf afforded 52 mg (65%) of 7 as a white

solid. [h]_D−24.3° (c 0.44, CH₂Cl₂); IR (thin ﬁlm):

2103, 1748, 1719, 1386, 1257 cm⁻^{1 1}H NMR (400

;

MHz, CDCl₃) l 7.93 (dd, J 1.2, 7.84 Hz, 1H), 7.90–

7.82 (m, 2H), 7.76–7.68 (m, 2H), 7.61–7.54 (m, 1H),

7.53–7.47 (m, 1H), 7.45–7.37 (m, 1H), 6.05 (dd, J 9.2,

10.6 Hz, 1H), 5.53 (d, J 8.5 Hz, 1H), 5.45 (dd, J 9.4,

10.0 Hz, 1H), 5.12 (d, J 5.1 Hz, 1H), 4.82 (d, J 14.4 Hz,

1H), 4.68 (d, J 14.4 Hz, 1H), 4.45–4.34 (m, 3H), 4.23

(dd, J 2.6, 12.3 Hz, 1H), 4.11 (dd, J 2.4, 5.1 Hz, 1H),

4.06–3.93 (m, 3H), 3.78–3.67 (m, 2H), 2.09 (s, 3H),

1.81 (s, 3H), 1.41 (s, 3H), 1.25 (s, 3H), 1.05 (s, 3H), 1.04

(s, 3H); ¹³C NMR (125 MHz, CDCl₃) l 170.9, 170.3,

165.2, 137.9, 133.9, 133.5, 131.3, 130.2, 128.5, 127.8,

123.7, 109.5, 108.1, 99.6, 96.1, 77.4, 71.8, 71.0, 70.8,

70.6, 70.3, 70.2, 69.9, 69.6, 67.7, 62.4, 54.8, 53.0, 26.0,

25.5, 24.8, 24.4, 20.9; ESI FT-MS: m/z (M+Na)⁺

calcd 817.2539, obsd 817.2555.

Synthesis of disaccharides using glycosyl trichloroacet-

imidates as glycosylating agents. General procedure A.—

A mixture of glucosamine trichloroacetimidate (1.3

equiv) and 1,2:3,4-di-O-isopropylidene-D-galactopyran-

ose (1) (1.0 equiv) was coevaporated with toluene, dried

under vacuum for 2 h, and dissolved in CH₂Cl₂. The

solution was cooled and TMSOTf or TBSOTf (0.13

equiv, 0.5 M in CH₂Cl₂) was added. Et₃N was added to

quench the reaction, the solution was concentrated in

vacuo, and the crude product was puriﬁed by ﬂash

silica gel chromatography (2:3 EtOAc–hexanes) to af-

ford the desired disaccharide.

Synthesis of disaccharides using glycosyl phosphates as

glycosylating agents. General procedure B.—A mixture

1910

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

3,4-Di-O-acetyl-2-deoxy-6-O-le6ulinyl-2-phthalimido-

toluene (3×3 mL), dried under vacuum for 1 h, and

dissolved in CH₂Cl₂(1.5 mL). The solution was cooled

to −20 °C, and TMSOTf (146 mL, 146 mmol, 1.0 M in

CH₂Cl₂) was added. After 3 h, Et₃N (100 mL) was

added, the solution was concentrated in vacuo, and the

crude product was puriﬁed by ﬂash silica gel chro-

matography (2:3 EtOAc–hexanes) to yield 74 mg (83%)

of 13 as a white solid. [h]_D−14.5° (c 0.92, CH₂Cl₂); IR

(thin ﬁlm): 1778, 1748, 1719, 1386 cm⁻¹; ¹H NMR (500

MHz, CDCl₃) l 7.90–7.69 (m, 4H), 5.85 (dd, J 9.2, 10.7

Hz, 1H), 5.46 (d, J 8.5 Hz, 1H), 5.18 (dd, J 9.5, 10.1

Hz, 1H), 5.10 (d, J 5.2 Hz, 1H), 4.40 (dd, J 2.4, 5.5 Hz,

1H), 4.32 (dd, J 4.9, 12.5 Hz, 1H), 4.30 (dd, J 8.6, 10.7

Hz, 1H), 4.18 (dd, J 2.1, 12.2 Hz, 1H), 4.10 (dd, J 2.4,

5.2 Hz, 1H), 3.99 (d, J 7.9 Hz, 1H), 3.88 (ddd, J 2.1,

4.6, 10.1 Hz, 1H), 3.76–3.65 (m, 2H), 2.80–2.63 (m,

2H), 2.58–2.44 (m, 2H), 2.15 (s, 3H), 2.11 (s, 3H), 1.90

(s, 3H), 1.39 (s, 3H), 1.23 (s, 3H), 1.02 (s, 6H); ¹³C

NMR (100 MHz, CDCl₃) l 206.1, 171.5, 170.9, 170.5,

133.9, 123.6, 109.4, 108.1, 99.5, 96.1, 77.4, 71.8, 71.0,

70.8, 70.5, 70.3, 69.5, 69.2, 67.6, 62.2, 54.8, 37.9, 30.0,

28.0, 26.0, 25.5, 24.8, 24.4, 21.0, 20.9, 20.7; ESI FT-MS:

m/z (M+Na)⁺calcd 756.2480, obsd 756.2474.

i-D-glucopyranosyl - (16) - 1,2:3,4 - di - O - isopropyli-

dene-h-^D-galactopyranose (9).—Coupling of 8 (241 mg,

0.38 mmol) and 1 (50 mg, 0.19 mmol following general

procedure A for 3 h at 0 °C using TMSOTf yielded 94

mg (68%) of 9 as a white solid. [h]_D−14.5° (c 0.92,

CH₂Cl₂); IR (thin ﬁlm): 1778, 1748, 1719, 1386, 1224

cm⁻¹;¹H NMR (500 MHz, CDCl₃) l 7.90–7.69 (m,

4H), 5.85 (dd, J 9.2, 10.7 Hz, 1H), 5.46 (d, J 8.5 Hz,

1H), 5.18 (dd, J 9.5, 10.1 Hz, 1H), 5.10 (d, J 5.2 Hz,

1H), 4.40 (dd, J 2.4, 5.5 Hz, 1H), 4.32 (dd, J 4.9, 12.5

Hz, 1H), 4.30 (dd, J 8.6, 10.7 Hz, 1H), 4.18 (dd, J 2.1,

12.2 Hz, 1H), 4.10 (dd, J 2.4, 5.2 Hz, 1H), 3.99 (d, J 7.9

Hz, 1H), 3.88 (ddd, J 2.1, 4.6, 10.1 Hz, 1H), 3.76–3.65

(m, 2H), 2.80–2.63 (m, 2H), 2.58–2.44 (m, 2H), 2.15 (s,

3H), 2.11 (s, 3H), 1.90 (s, 311), 1.39 (s, 3H), 1.23 (s,

3H), 1.02 (s, 6H); ¹³C NMR (100 MHz, CDCl₃) l

206.1, 171.5, 170.9, 170.5, 133.9, 123.6, 109.4, 108.1,

99.5, 96.1, 77.4, 71.8, 71.0, 70.8, 70.5, 70.3, 69.5, 69.2,

67.6, 62.2, 54.8, 37.9, 30.0, 28.0, 26.0, 25.5, 24.8, 24.4,

21.0, 20.9, 20.7; ESI FT-MS: m/z (M+Na)⁺calcd

756.2480, obsd 756.2474.

3,4-Di-O-benzyl-2-deoxy-6-O-le6ulinyl-2-phthalimido-

i-D - glucopyranosyl - (16) - 1,2:3,4 - di - O - isopropyli-

dene-h-^D-galactopyranose (11).—Glucosamine phos-

phate 10 (101 mg, 0.128 mmol) and galactopyranoside

acceptor 1 (27 mg, 0.10 mmol) were azeotroped with

toluene (3×3 mL), dried under vacuum for 1 h, and

dissolved in CH₂Cl₂(1.3 mL). The solution was cooled

to −15 °C, and TMSOTf (103 mL, 103 mmol, 1.0 M in

CH₂Cl₂) was added. After 2 h, Et₃N (100 mL) was

added, the solution was concentrated in vacuo, and the

crude product was puriﬁed by ﬂash silica gel chro-

matography (1:4 EtOAc–hexanes) to yield 74 mg (85%)

of 11 as a white solid. [h]_D−8.97° (c 1.01, CH₂Cl₂); IR

(thin ﬁlm): 1776, 1715, 1387, 1069 cm⁻¹; ¹H NMR (500

MHz, CDCl₃) l 7.90–7.53 (m, 4H), 7.42–7.28 (m, 5H),

7.06–6.96 (m, 2H), 6.95–6.78 (m, 3H), 5.22 (d, J 8.5

Hz, 1H), 5.08 (d, J 5.1 Hz, 1H), 4.89 (d, J 10.8 Hz, 1H),

4.81 (d, J 11.9 Hz, 1H), 4.65 (d, J 10.8 Hz, 1H), 4.45 (d,

J 11.9 Hz, 1H), 4.55–4.26 (m, 4H), 4.16 (dd, J 8.6, 10.7

Hz, 1H), 4.07 (dd, J 2.3, 5.1 Hz, 1H), 3.96 (dd, J 1.2,

8.0 Hz, 1H), 3.89 (dd, J 7.4, 15.2 Hz, 1H), 3.74–3.67

(m, 2H), 3.67–3.56 (m, 2H), 2.87–2.69 (m, 2H), 2.68–

2.54 (m, 2H), 2.22 (s, 3H), 1.37 (s, 3H), 1.21 (s, 3H),

1.01 (s, 3H), 0.99 (s, 3H); ¹³C NMR (125 MHz, CDCl₃)

l 207.1, 173.2, 138.6, 138.4, 134.0, 132.8, 129.2, 128.8,

128.7, 128.6, 128.5, 128.1, 123.9, 109.9, 100.2, 96.6,

80.0, 79.9, 75.7, 75.6, 73.4, 71.5, 71.3, 70.8, 69.8, 68.0,

63.8, 56.5, 38.6, 30.6, 28.7, 26.6, 26.0, 25.4, 24.9; ESI

FT-MS: m/z (M+Na)⁺calcd 852.3208, obsd 852.2868.

3,4-Di-O-acetyl-2-deoxy-6-O-le6ulinyl-2-phthalimido-

i - D - glucopyranosyl - (16) - 1,2:3,4 - di - O - isopropyl-

idene-h-^D-galactopyranose (13).—Glucosamine phos-

phate 12 (100 mg, 0.146 mmol) and galactopyranoside

acceptor 1 (32 mg, 0.12 mmol) were azeotroped with

6-O - Acetyl - 3,4 - di - O - benzyl - 2 - benzyloxycarbonyl-

amino-2-deoxy-i-D -glucopyranosyl-(16)-1,2:3,4-di-

O-isopropylidene-h-D-galactopyranose (15).—A mixture

of glucosamine trichloroacetimidate 14 (51 mg, 75

mmol) and galactopyranoside 1 (16 mg, 63 mmol) were

coevaporated with toluene (3×3 mL), dried under

vacuum for 2 h, and dissolved in CH₂Cl₂(1.0 mL). The

solution was cooled to 0 °C, and TMSOTf (15 mL, 7.5

mmol, 0.5 M in CH₂C1₂) was added. After 1 h, Et₃N (50

mL) was added, the solution was concentrated in vacuo,

and the crude product was puriﬁed by ﬂash silica gel

chromatography (2:3 EtOAc–hexanes) to afford 41 mg

(88%) of 15 as a white solid. [h]_D−18.3° (c 1.01,

CH₂Cl₂); IR (thin ﬁlm): 3339, 1739, 1540, 1240 cm⁻¹

;

¹H NMR (500 MHz, CDCl₃) l 7.39–7.21 (m, 15H),

5.51 (d, J 5.0 Hz, 1H), 5.13 (d, J 12.3 Hz, 1H), 5.07 (d,

J 12.3 Hz, 1H), 4.84 (d, J 11.0 Hz, 1H), 4.77 (d, J 11.0

Hz, 1H), 4.69 (d, J 11.0 Hz, 1H), 4.59–4.53 (m, 2H),

4.34 (d, J 11.0 Hz, 1H), 4.30 (dd, J 2.4, 5.0 Hz, 1H),

4.24 (dd, J 2.4, 11.9 Hz, 1H), 4.18 (d, J 8.0 Hz, 1H),

4.01–3.96 (m, 2H), 3.94 (d, J 4.3 Hz, 1H), 3.76 (dt, J

3.4, 9.3 Hz, 1H), 3.57 (d, J 5.3 Hz, 2H), 2.05 (s, 3H),

1.49 (s, 3H), 1.45 (s, 3H), 1.32 (s, 3H), 1.30 (s, 3H); ¹³C

NMR (100 MHz, CDCl₃) l 171.0, 156.2, 138.3, 137.9,

136.7, 128.7, 128.6, 128.5, 128.2, 127.9, 109.5, 108.9,

101.0, 96.4, 81.8, 78.2, 77.4, 75.3, 74.9, 73.1, 71.3, 70.8,

70.6, 68.4, 68.0, 66.9, 63.4, 57.7, 29.9, 26.2, 25.1, 24.5,

21.1; ESI FT-MS: m/z (M+Na)⁺calcd 800.3252, obsd

800.3234.

3,4-Di-O-acetyl- 2-benzyloxycarbonylamino-2-deoxy-

6 - O - le6ulinyl - i - D - glucopyranosyl - (16)1,2:3,4-di-

O-isopropylidene-h-D-galactopyranose

(17).—Gluco-

samine trichloroacetimidate 16 (74 mg, 0.12 mmol) and

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

1911

galactopyranoside acceptor 1 (25 mg, 96.0 mmol) were

O-isopropylidene-h-^D-galactopyranoside

(21).—Glu-

azeotroped with toluene (3×3 mL), dried under vac-

uum for 1 h, and dissolved in CH₂Cl₂(1.00 mL). The

solution cooled to 0 °C, and TMSOTf (24 mL, 12 mmol,

0.5 M in CH₂Cl₂) was added. After 1 h Et₃N (100 mL)

was added, the solution was concentrated in vacuo, and

the crude product was puriﬁed by ﬂash silica gel chro-

matography (2:3 EtOAc–hexanes) to yield 63 mg (90%)

of 17 as a white solid. [h]_D−18.5° (c 1.03, CH₂Cl₂); IR

cosamine phosphate 20 (80 mg, 0.116 mmol) and

galactopyranoside acceptor 1 (20 mg, 77 mmol) were

azeotroped with toluene (3×3 mL), dried under vac-

uum for 1 h, and dissolved in CH₂Cl₂(1 mL). The

solution was cooled to −20 °C, and TMSOTf (116 mL,

116 mmol, 1.0 M in CH₂Cl₂) was added. After 2 h, Et₃N

(100 mL) was added, the solution was concentrated in

vacuo, and the crude product was puriﬁed by ﬂash

silica gel chromatography (2:3 EtOAc–hexanes) to

yield 45 mg (81%) of 21 as a white solid. [h]_D−18.5 (c

1.03, CH₂Cl₂); IR (thin ﬁlm): 3348, 2986, 1746, 1350,

(thin ﬁlm): 3348, 2986, 1746, 1350, 1372 cm^{−1 1}H

;

NMR (500 MHz, CDCl₃) l 7.37–7.27 (m, 5H), 5.50 (d,

J 5.2 Hz, 1H), 5.25–5.12 (m, 2H), 5.07 (dd, J 9.4, 9.5

Hz, 1H), 5.02–4.96 (m, 2H), 4.86–4.78 (m, 1H), 4.55

(dd, J 2.4, 7.93 Hz, 1H), 4.28 (dd, J 2.4, 4.9 Hz, 1H),

4.26 (dd, J 4.6, 12.2 Hz, 1H), 4.16 (dd, J 1.5, 7.9 Hz,

1H), 4.12 (dd, J 2.1, 12.5 Hz, 1H), 4.00–3.90 (m, 2H),

3.80 (dd, J 7.6, 12.2 Hz, 1H), 3.78–3.66 (m, 2H),

2.79–2.62 (m, 2H), 2.54–2.40 (m, 2H), 2.15 (s, 3H),

2.07(s, 3H), 1.95 (s, 3H), 1.44 (s, 3H), 1.43 (s, 3H), 1.31

(s, 3H), 1.26 (s, 3H); ¹³C NMR (125 MHz, CDCl₃) l

206.2, 171.5, 171.1, 171.0, 156.1, 136.6, 128.6, 128.3,

128.2, 109.6, 109.0, 96.4, 77.4, 72.7, 72.0, 71.3, 70.8,

70.4, 68.8, 68.6, 67.0, 62.2, 56.2, 37.9, 29.8, 27.9, 26.1,

25.1, 24.5, 21.0, 20.8; ESI FT-MS: m/z (M+Na)⁺

calcd 760.2793, obsd 760.2756.

1

1372 cm⁻¹; H NMR (500 MHz, CDCl₃) l 7.37–7.27

(m, 5H), 5.50 (d, J 5.2 Hz, 1H), 5.25–5.12 (m, 2H), 5.07

(dd, J 9.4, 9.5 Hz, 1H), 5.02–4.96 (m, 2H), 4.86–4.78

(m, 1H), 4.55 (dd, J 2.4, 7.9 Hz, 1H), 4.28 (dd, J 2.4,

4.9 Hz, 1H), 4.26 (dd, J 4.6, 12.2 Hz, 1H), 4.16 (dd, J

1.5, 7.9 Hz, 1H), 4.12 (dd, J 2.1, 12.5 Hz, 1H), 4.00–

3.90 (m, 2H), 3.80 (dd, J 7.6, 12.2 Hz, 1H), 3.78–3.66

(m, 2H), 2.79–2.62 (m, 2H), 2.54–2.40 (m, 2H), 2.15 (s,

3H), 2.07 (s, 3H), 1.95 (s, 3H), 1.44 (s, 3H), 1.43 (s,

3H), 1.31 (s, 3H), 1.26 (s, 3H); ¹³C NMR (125 MHz,

CDCl₃) l 206.2, 171.5, 171.1, 171.0, 156.1, 136.6, 128.6,

128.3, 128.2, 109.6, 109.0, 96.4, 77.4, 72.7, 72.0, 71.3,

70.8, 70.4, 68.8, 68.6, 67.0, 62.2, 56.2, 37.9, 29.8, 27.9,

26.1, 25.1, 24.5, 21.0, 20.8; ESI FT-MS: m/z (M+

Na)⁺calcd 760.2793, obsd 760.2756.

3,4-Di-O-benzyl-2-benzyloxycarbonylamino-2-deoxy-

6-O-le6ulinyl-i-D-glucopyranosyl-(16)-1,2:3,4-di-O-

isopropylidene-h-D-galactopyranose

(19).—Glucos-

6-O-Acetyl-3,4-di-O-benzyl-2-deoxy-2-(2,2,2-tri-

chloroethoxycarbonylamino)-i-D-glucopyranosyl-(16)-

1,2;3,4-di-O-isopropylidene-h-D-galactopyranose (23).—

Glucosamine trichloroacetimidate 22 (126 mg, 0.18

mmol) and galactopyranoside 1 (38 mg, 0.15 mmol)

were azeotroped with toluene (3×3 mL), dried under

vacuum for 1 h, and dissolved in CH₂Cl₂(1.7 mL). The

solution was cooled to −20 °C, and TBSOTf (36 mL,

18 mmol, 0.5 M in CH₂Cl₂) was added. After 1 h, Et₃N

(100 mL) was added, the solution was concentrated in

vacuo, and the crude product was puriﬁed by ﬂash

silica gel chromatography (2:3 EtOAc–hexanes) to

yield 103 mg (87%) of 23 as a white solid. [h]_D+25.0°

(c 0.40, CH₂Cl₂); IR (thin ﬁlm): 3342, 1740, 1537, 1236,

amine phosphate 18 (117 mg, 0.15 mmol) and

galactopyranoside acceptor 1 (26 mg, 0.10 mmol) were

azeotroped with toluene (3×3 mL), dried under vac-

uum for 1 h, and dissolved in CH₂Cl₂(1 mL). The

solution was cooled to −20 °C, and TMSOTf (150 mL,

150 mmol, 1.0 M in CH₂Cl₂) was added. After 2 h, Et₃N

(100 mL) was added, the solution was concentrated in

vacuo, and the crude product was puriﬁed by ﬂash

silica gel chromatography (1:4 EtOAc–hexanes) to

yield 75 mg (91%) of 19 as a white solid. [h]_D−8.9° (c

1.01, CH₂Cl₂); IR (thin ﬁlm): 1776, 1715, 1387, 1069

1

cm⁻¹; H NMR (500 MHz, CDCl₃) l 7.37–7.20 (m,

15H), 5.49 (d, J 15.0 Hz, 1H), 5.12 (d, J 12.3 Hz, 1H),

5.05 (d, J 12.3 Hz, 2H), 4.83 (d, J 10.9 Hz, 1H), 4.76 (d,

J 11.0 Hz, 1H), 4.67 (d, J 11.0 Hz, 1H), 4.57 (d, J 10.8

Hz, 1H), 4.54 (dd, J 2.4, 9.4 Hz, 1H), 4.34 (d, J 11.6

Hz, 1H), 4.30–4.22 (m, 2H), 4.18 (d, J 8.0 Hz, 1H),

3.99–3.88 (m, 3H), 3.78–3.69 (m, 1H), 3.59–3.52 (m,

2H), 2.76–2.69 (m, 1H), 2.62–2.53 (m, 2H), 2.14 (s,

3H), 1.47 (s, 3H), 1.42 (s, 3H), 1.30 (s, 3H), 1.27 (s,

3H); ¹³C NMR (125 MHz, CDCl₃) l 206.5, 172.6,

156.1, 138.2, 137.9, 136.7, 128.6, 128.1, 128.0, 127.9,

109.5, 108.8, 100.9, 96.4, 81.7, 78.2, 77.4, 75.2, 74.9,

73.0, 71.2, 70.8, 70.5, 68.3, 67.8, 66.8, 63.4, 57.5, 38.0,

30.0, 28.0, 26.1, 25.1, 24.5; ESI FT-MS: m/z (M+

Na)⁺calcd 856.3521, obsd 856.3546.

1

1070 cm⁻¹; H NMR (400 MHz, CDCl₃) l 7.42–7.19

(m, 10H), 5.51 (d, J 5.0 Hz, 2H), 5.25 (bs, 1H), 4.85 (d,

J 10.8 Hz, 1H), 4.82 (d, J 11.1 Hz, 1H), 4.77 (d, J 11.1

Hz, 1H), 4.68–4.61 (m, 1H), 4.61–4.54 (m, 2H), 4.40–

4.33 (m, 1H), 4.30 (dd, J 2.4, 5.0 Hz, 1H), 4.27–4.21

(m, 1H), 4.19 (dd, J 1.7, 7.9 Hz, 1H), 4.01–3.84 (m,

3H), 3.72 (dd, J 8.5, 12.5 Hz, 1H), 3.64–3.55 (m, 2H),

3.55–3.41 (m, 1H), 2.00 (s, 3H), 1.54 (s, 3H), 1.44 (s,

3H), 1.33 (s, 3H); ¹³C NMR (100 MHz, CDCl₃) l

170.9, 154.3, 138.1, 137.8, 128.7, 128.6, 128.2, 128.0,

109.5, 108.8, 101.0, 96.4, 95.7, 81.2, 78.3, 77.4, 75.1,

75.0, 74.7, 73.1, 70.9, 70.8, 70.7, 68.6, 67.9, 63.2, 57.7,

56.2, 56.1, 25.2, 24.5, 24.4, 21.1; ESI FT-MS: m/z

(M+Na)⁺calcd 840.1927, obsd 840.1937.

3,4-Di-O-acetyl-2-deoxy-6-O-le6ulinyl-2-benzyloxy-

carbonylamino-i-D - glucopyranosyl-(16)-1,2:3,4-di-

1912

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

3,4-Di-O-acetyl-2-deoxy-6-O-le6ulinyl-2-trichloro-

acetylamino-i-D-glucopyranosyl-(16)-1,2:3,4-di-O-

isopropylidene-h-^D-galactopyranose (25).—Glucos-

amine trichloroacetimidate 24 (78 mg, 0.12 mmol) and

galactopyranoside (26 mg, 0.10 mmol) were

128.2, 128.2, 128.2, 128.1, 128.1, 109.5, 108.8, 97.8,

96.4, 92.6,79.5, 78.0, 77.4, 75.0, 74.8, 73.1, 71.1, 70.7,

70.6, 68.7, 66.9, 63.4, 57.6, 38.3, 38.1, 30.1, 28.1, 26.3,

26.2, 25.1, 24.6; ESI FT-MS: m/z (M+Na)⁺calcd

866.2083, obsd 866.2071.

1

azeotroped with toluene (3×3 mL) and dried under

vacuum for 1 h. CH₂Cl₂(1.0 mL) was added to the

mixture, the solution cooled to −20 °C, and a solution

of TMSOTf (24.0 mL, 0.012 mmol, 0.5 M in CH₂Cl₂)

was added. After 1 h, Et₃N (100 mL) was added, the

solution was concentrated in vacuo, and the crude

product was puriﬁed by ﬂash silica gel chromatography

(2:3 EtOAc–hexanes) to afford 66 mg (88%) of 25 as a

white solid. [h]_D−28.5° (c 0.84, CH₂Cl₂); IR (thin

Methyl 3,4-di-O-benzyl-2-deoxy-6-O-le6ulinyl-2-ph-

thalimido-i-^D-glucopyranosyl-(13)-2,4,6-tri-O-benz-

yl-h-^D-galactopyranoside (29).—Glucosamine phos-

phate 10 (63 mg, 81 mmol) and galactopyranoside ac-

ceptor 28 (25 mg, 54 mmol) were azeotroped with

toluene (3×3 mL), dried under vacuum for 1 h, and

dissolved in CH₂Cl₂(1 mL). The solution was cooled to

−20 °C, and TMSOTf (81 mL, 81 mmol, 1.0 M in

CH₂Cl₂) was added. After 2 h, Et₃N (100 mL) was

added, the solution was concentrated in vacuo, and the

crude product was puriﬁed by ﬂash silica gel chro-

matography (1:4 EtOAc–hexanes) to yield 54 mg (96%)

of 29 as a white solid. [h]_D+10.8° (c 1.00, CH₂Cl₂); IR

(thin ﬁlm): 1775, 1715, 1389, 1099 cm⁻¹; ¹H NMR (500

MHz, CDCl₃) l 7.62–7.32 (m, 4H), 7.23–7.12 (m,

10H), 7.12–7.06 (m, 4H), 7.02–6.97 (m, 3H), 6.88–6.84

(m, 2H), 6.81–6.73 (m, 3H), 6.72–6.67 (m, 1H), 5.27

(d, J 8.2 Hz, 1H), 4.78 (d, J 11.3 Hz, 1H), 4.73 (d, J

11.0 Hz, 1H), 4.68 (d, J 11.9 Hz, 1H), 4.50 (d, J 11.0

Hz, 1H), 4.39 (dd, J 8.2, 10.7 Hz, 1H), 4.34 (d, J 11.6

Hz, 1H), 4.30 (d, J 11.9 Hz, 1H), 4.27 (d, J 11.9 Hz,

1H), 4.21 (d, J 11.9 Hz, 1H), 4.17 (3d, J 4.6, 11.9 Hz,

1H), 4.14 (dd, J 8.6, 11.0 Hz, 1H), 4.01 (d, J 3.7 Hz,

1H), 3.95 (d, J 12.8 Hz, 1H), 3.86 (dd, J 2.8, 10.1 Hz,

1H), 3.84–3.80 (m, 1H), 3.70–3.68 (m, 1H), 3.62–3.56

(m, 2H), 3.54 (dd, J 8.2, 9.8 Hz, 1H), 3.44 (dd, J 3.7,

10.1 Hz, 1H), 3.29 (dd, J 2.1, 6.1 Hz, 1H), 3.00 (s, 3H),

2.47–2.40 (m, 2H), 2.34–2.28 (m, 2H), 1.93 (s, 3H); ¹³C

NMR (100 MHz, CDCl₃) l 206.3, 172.6, 167.9, 167.8,

139.1, 138.6, 138.3, 138.1, 137.7, 133.9, 131.7, 128.7,

128.5, 128.4, 128.3, 128.2, 128.1, 127.8, 127.7, 127.6,

127.5, 127.1, 123.4, 99.8, 98.8, 79.5, 79.4, 78.9, 77.7,

77.4, 75.3, 75.2, 75.1, 73.5, 72.8, 69.6, 69.2, 69.6, 69.2,

63.1, 56.6, 55.2, 37.9, 29.9, 28.0; ESI FT-MS: m/z

(M+Na)⁺calcd 1056.4147, obsd 1056.4141.

ﬁlm): 3320, 1749, 1717, 1373 cm⁻^{1 1}H NMR (400

;

MHz, CDCl₃) l 7.09 (d, J 8.9 Hz, 1H), 5.43 (d, J 5.0

Hz, 1H), 5.37 (dd, J 9.5, 10.5 Hz, 1H), 5.10 (dd, J 9.7,

9.7 Hz, 1H), 4.77 (d, J 8.3 Hz, 1H), 4.53 (dd, J 2.3, 7.9

Hz, 1H), 4.28–4.20 (m, 2H), 4.17 (dd, J 1.7, 7.9 Hz,

1H), 4.11 (dd, J 2.0, 12.3 Hz, 1H), 4.05–3.93 (m, 2H),

3.93–3.84 (m, 1H), 3.73 (ddd, J 2.1, 4.8, 9.9 Hz, 1H),

3.66 (dd, J 6.8, 10.8 Hz, 1H), 2.83–2.71 (m, 1H),

2.71–2.59 (m, 1H), 2.53–2.34 (m, 2H), 2.13 (s, 3H),

2.05 (s, 3H), 2.04 (s, 3H), 1.44 (s, 3H), 1.39 (s, 3H), 1.29

(s, 3H), 1.26 (s, 3H); ¹³C NMR (100 MHz, CDCl₃) l

206.7, 171.7, 171.0, 162.2, 109.3, 108.7, 101.0, 96.3,

92.4, 77.4, 72.2, 71.6, 71.0, 70.6, 70.5, 68.5, 67.2, 62.1,

55.9, 37.8, 29.8, 29.7, 27.8, 26.3, 26.1, 25.1, 24.5, 20.9,

20.8; ESI FT-MS: m/z (M+Na)⁺calcd 770.1362, obsd

770.1356.

3,4-Di-O-benzyl-2-deoxy-6-O-le6ulinyl-2-trichloro-

acetylamino-i-D-glucopyranosyl-(16)-1,2:3,4-di-O-

isopropylidene-h-D-galactopyranose

(27).—Glucos-

amine phosphate 26 (67 mg, 86 mmol) and galactopy-

ranoside acceptor 1 (19 mg, 71 mmol) were azeotroped

with toluene (3×1 mL), then dried under vacuum for 3

h. Residue dissolved in CH₂Cl₂(2 mL) and cooled to

−20 °C. TMSOTf (15 mL, 85 mmol) was added, and the

solution was allowed to slowly warm to −10 °C over

30 min, before quenching with TEA (20 mL). The

reaction mixture was warmed to ambient temperature

and concentrated in vacuo. The resulting residue was

puriﬁed by ﬂash silica gel chromatography (25:75

40:60 EtOAc–hexanes) to afford 33 mg (50%) of the

desired disaccharide 27 as a white solid. [h]_D−22.4° (c

2.16 CH₂Cl₂); IR (thin ﬁlm): 3325, 2988, 1736, 1718,

1697 cm⁻¹;¹H NMR (400 MHz, CDCl₃) l 7.36–7.27

(m, 10H), 7.14 (d, J 7.8 Hz, 1H), 5.49 (d, J 5.0 Hz, 1H),

4.92 (d, J 7.5 Hz, 1H), 4.82 (d, J 11.0 Hz, 1H), 4.89 (d,

J 11.1 Hz, 1H), 4.74 (d, J 10.8 Hz, 1H), 4.61 (d, J 10.9

Hz, 1H), 4.57 (dd, J 1.8, 7.9 Hz, 1H), 4.16 (dd, J 7.9,

9.4 Hz, 1H), 4.01 (dd, J 5.5, 10.6 Hz, 1H), 3.96–3.92

(m, 1H), 3.72–3.59 (m, 4H), 2.78–2.72 (m, 2H), 2.60

(app t, J 6.4 Hz, 2H), 2.19 (s, 3H), 1.50 (s, 3H), 1.43 (s,

3H), 1.32 (s, 3H), 1.31 (s, 3H); ¹³C NMR (100 MHz,

CDCl₃) l 206.6, 172.7, 162.1, 137.8, 137.6, 128.7, 128.3,

n-Pentenyl-3,4-di-O-benzyl-2-deoxy-6-O-le6ulinyl-2-

phthalimido-i-D-glucopyranosyl-(14)-3,6-di-O-benz-

yl-2-O-pi6aloyl-i-D-glucopyranoside

(31).—Glucos-

amine phosphate 10 (91 mg, 117 mmol) and glucopyran-

oside acceptor 30 (40 mg, 78 mmol) were azeotroped

with toluene (3×3 mL), dried under vacuum for 1 h,

and dissolved in CH₂Cl₂(1 mL). The solution was

cooled to −20 °C, and TMSOTf (234 mL, 117 mmol,

0.5 M in CH₂Cl₂) was added. After 2 h, Et₃N (100 mL)

was added, the solution was concentrated in vacuo, and

the crude product was puriﬁed by ﬂash silica gel chro-

matography (1:4 EtOAc–hexanes) to yield 60 mg (71%)

of 31 as a white solid. [h]_D+1.55° (c 0.91, CH₂Cl₂); IR

(thin ﬁlm): 1775, 1738, 1713, 1388, 1153 cm⁻^{1 1}H

;

NMR (400 MHz, CDCl₃) l 7.85–7.53 (m, 4H), 7.39–

7.18 (m, 17H), 7.00–6.95 (m, 2H), 6.95–6.82 (m, 3H),

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

1913

(m, 3H), 5.80–5.67 (m, 1H), 5.37 (d, J 8.4 Hz, 1H),

4.99–4.88 (m, 4H), 4.81 (d, J 10.8 Hz, 1H), 4.79 (d, J

11.9 Hz, 1H), 4.60 (d, J 11.9 Hz, 1H), 4.58 (d, J 10.8

Hz, 1H), 4.44–4.28 (m, 4H), 4.22 (d, J 7.9 Hz, 1H),

4.17–4.09 (m, 2H), 4.08–3.99 (m, 2H), 3.75–3.67 (m,

1H), 3.65–3.57 (m, 2H), 3.47 (dd, J 1.5, 11.1 Hz, 1H),

3.40–3.28 (m, 3H), 3.27–3.20 (m, 1H), 2.70–2.51 (m,

2H), 2.49–2.39 (m, 1H), 2.36–2.25 (m, 1H), 2.14 (s,

3H), 2.06–1.95 (m, 2H), 1.62–1.51 (m, 2H), 1.08 (s,

9H); ¹³C NMR (100 MHz, CDCl₃) l 206.7, 176.8,

172.5, 139.1, 138.3, 138.1, 137.9, 137.7, 134.0, 128.7,

128.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.6, 127.5,

127.1, 126.8, 123.4, 114.9, 101.1, 97.4, 81.3, 79.5, 79.2,

75.1, 74.8, 73.4, 72.8, 72.7, 72.5, 68.9, 68.2, 62.7, 56.6,

38.8, 38.0, 30.1, 29.9, 28.8, 27.9, 27.2; ESI FT-MS: m/z

(M+Na)⁺calcd 1104.4722, obsd 1104.4171.

for 1 h, then diluted with Et₂O (10 mL), washed with

HCl (10% in H₂O, 3×5 mL), H₂O, brine, and dried

over Na₂SO₄. After ﬁltration and concentration in

vacuo, the crude product was puriﬁed by ﬂash silica gel

chromatography (2:3 EtOAc–hexanes) to yield 79.7 mg

(94%) of n-pentenyl 3,4-di-O-benzyl-2-deoxy-2-phthal-

imido-b-

deoxy-2-phthalimido-b-

foam. [h]_D+31.8° (c 0.98, CH₂Cl₂); IR (thin ﬁlm):

3062, 1774, 1713, 1388 cm⁻^{1 1}H NMR (500 MHz,

D

-glucopyranosyl-(16)-3,4-di-O-benzyl-2-

D-glucopyranoside as a white

;

CDCl₃) l 7.82–7.52 (m, 8H), 7.42–7.21 (m, 10H),

7.15–7.09 (m, 2H), 7.03–6.98 (m, 2H), 6.97–6.93 (m,

2H), 6.91–6.80 (m, 6H), 5.55–5.46 (m, 1H), 5.27 (d, J

8.2 Hz, 1H), 4.98 (d, J 8.6 Hz, 1H), 4.90 (d, J 11.0 Hz,

1H), 4.82 (d, J 12.2 Hz, 1H), 4.75 (d, J 10.7 Hz, 1H),

4.73–4.69 (m, 1H), 4.64 (ddd, J 1.8, 3.7, 17.1 Hz, 1H),

4.58 (d, J 10.7 Hz, 1H), 4.46 (d, J 12.2 Hz, 1H), 4.40 (d,

J 11.0 Hz, 1H), 4.39 (dd, J 8.5, 10.7 Hz, 1H), 4.34 (d,

J 12.2 Hz, 1H), 4.23 (dd, J 8.3, 10.7 Hz, 1H), 4.23–4.20

(m, 1H), 4.04 (dd, J 8.2, 11.0 Hz, 1H), 3.99 (d, J 10.4

Hz, 1H), 3.96–3.90 (m, 1H), 3.84–3.68 (m, 4H), 3.59–

3.46 (m, 4H), 3.24–3.16 (m, 1H), 2.26–2.20 (m, 1H),

1.80–1.68 (m, 2H), 1.43–1.26 (m, 2H); ¹³C NMR (100

MHz, CDCl₃) l 168.3, 167.7, 138.1, 138.0, 137.7, 133.8,

131.6, 128.7, 128.5, 128.3, 128.2, 128.1, 128.0, 127.9,

127.5, 127.2, 127.0, 123.4, 114.7, 98.4, 98.2, 79.7, 79.6,

79.3, 79.2, 77.4, 75.5, 75.2, 75.0, 74.8, 74.7, 68.8, 68.4,

62.0, 55.9, 29.9, 28.5; ESI FT-MS: m/z (M+Na)⁺

calcd 1051.3993, obsd 1051.3974.

n-Pentenyl-3,4-di-O-benzyl-2-deoxy-6-O-le6ulinyl-2-

phthalimido-i-^D-glucopyranosyl-(16)-3,4-di-O-benz-

yl-2-deoxy-2-phthalimido-i-D-glucopyranoside (33).—

Glucosamine phosphate (10) (112 mg, 143 mmol) and

n-pentenyl glucosamine acceptor 32 (70 mg, 119 mmol)

were azeotroped with toluene (3×3 mL), dried under

vacuum for 1 h, and dissolved in CH₂C1₂(2 mL). The

solution was cooled to −20 °C, and TMSOTf (143 mL,

143 mmol, 1.0 M in CH₂Cl₂) was added. After 2 h, Et₃N

(100 mL) was added, the solution was concentrated in

vacuo, and the crude product was puriﬁed by ﬂash

silica gel chromatography (1:4 EtOAc–hexanes) to

yield 103 mg (77%) of 33 as a white foam. [h]_D+27.4°

(c 1.04, CH₂Cl₂); IR (thin ﬁlm): 1774, 1714, 1453, 1389

Glucosamine phosphate (10) (88 mg, 112 mmol) and

n-pentenyl 3,4-di-O-benzyl-2-deoxy-2-phthalimido-b-D-

1

cm⁻¹; H NMR (400 MHz, CDCl₃) l 7.78–7.38 (m,

glucopyranosyl-(16)-3,4-di-O-benzyl-2-deoxy-2-ph-

thalimido-b- -glucopyranoside (77 mg, 75 mmol) were

8H), 7.35–7.13 (m, 9H), 7.13–7.01 (m, 2H), 7.01–6.89

(m, 2H), 6.89–6.65 (m, 8H), 5.52–5.31 (m, 1H), 5.21

(d, J 8.4 Hz, 1H), 4.88 (d, J 8.5 Hz, 1H), 4.83 (d, J 10.8

Hz, 1H), 4.74 (d, J 12.2 Hz, 1H), 4.67–4.51 (m, 4H),

4.46 (d, J 10.7 Hz, 1H), 4.42–4.19 (m, 6H), 4.18–4.08

(m, 2H), 4.02 (d, J 9.6 Hz, 1H), 3.95 (dd, J 8.5, 10.8 Hz,

1H), 3.71–3.53 (m, 3H), 3.48–3.38 (m, 2H), 3.34 (dd, J

8.6, 9.8 Hz, 1H), 3.17–3.02 (m, 1H), 2.74–2.60 (m, 2H),

2.59–2.47 (m, 2H), 2.11 (s, 3H), 1.70–1.57 (m, 2H),

1.36–1.13 (m, 2H); ¹³C NMR (100 MHz, CDC1₃) l

206.5, 172.6, 168.2, 167.7, 138.0, 137.9, 137.7, 137.6,

133.8, 131.6, 128.7, 128.6, 128.5, 128.3, 128.2, 128.1,

128.0, 127.9, 127.8, 127.5, 127.4, 123.4, 114.6, 98.0,

79.8, 79.4, 79.2, 77.4, 75.2, 75.0, 74.7, 74.6, 73.1, 68.5,

67.7, 63.0, 55.8, 55.7, 38.0, 30.0, 29.8, 28.4,28.1; ESI

FT-MS: m/z (M+Na)⁺calcd 1149.4361, obsd

1149.4328.

n-Pentenyl 3,4-di-O-benzyl-2-deoxy-6-O-le6ulinyl-2-

phthalimido-i-D-glucopyranosyl-(16)-3,4-di-O-benz-

yl-2-deoxy-2-phthalimido-i-D-glucopyranosyl-(16)-

3,4-di-O-benzyl-2-deoxy-2-phthalimido-i-D-glucopy-

ranoside (34).—Disaccharide 33 (93.0 mg, 82.5 mmol)

was dissolved in pyridine (0.60 mL) and AcOH (0.40

mL) at 0 °C. Hydrazine monohydrate (20 mL, 0.41

mmol) was added, and the reaction mixture was stirred

D

azeotroped with toluene (3×3 mL), dried under vac-

uum for 1 h, and dissolved in CH₂Cl₂(1 mL). The

solution was cooled to −20 °C, and TMSOTf (112 mL,

112 mmol, 1.0 M in CH₂Cl₂) was added. After 2 h, Et₃N

(100 mL) was added, the solution was concentrated in

vacuo, and the crude product was puriﬁed by ﬂash

silica gel chromatography (1:4 EtOAc–hexanes) to

yield 94 mg (79%) of 34 as a white foam. [h]_D+23.4°

(c 1.00, CH₂Cl₂); IR (thin ﬁlm): 1774, 1713, 1388, 1108

1

cm⁻¹; H NMR (500 MHz, CDCl₃) l 7.82–7.44 (m,

12H), 7.37–7.22 (m, 13H), 7.19–7.11 (m, 5H), 7.03–

6.98 (m, 3H), 6.95–6.77 (m, 13H), 5.53–5.43 (m, 1H),

5.32 (d, J 8.6 Hz, 1H), 5.12 (d, J 8.6 Hz, 1H), 4.91 (d,

J 8.6 Hz, 1H), 4.89 (d, J 10.9 Hz, 1H), 4.81 (d, J 12.2

Hz, 1H), 4.72–4.58 (m, 5H), 4.52 (d, J 10.4 Hz, 1H),

4.48–4.36 (m, 6H), 4.36–4.08 (m, 1H), 4.01 (d, J 8.5

Hz, 1H), 3.98 (d, J 8.5 Hz, 1H), 3.96–3.91 (m, 1H),

3.78 (dd, J 4.9, 11.3 Hz, 1H), 3.75–3.66 (m, 3H),

3.56–3.43 (m, 5H), 3.39–3.31 (m, 2H), 3.19–3.11 (m,

1H), 2.80–2.66 (m, 2H), 2.64–2.56 (m, 2H), 2.20 (s,

3H), 1.75–1.64 (m, 4H); ¹³C NMR (125 MHz, CDCl₃)

l 206.6, 172.6, 168.2, 167.7, 138.1, 138.0, 137.9, 137.8,

137.7, 137.6, 133.7, 131.6, 128.6, 128.5, 128.3, 128.2,

128.1, 128.0, 127.9, 127.8, 127.5, 127.4, 123.4, 114.6,

1914

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

98.1, 97.9, 79.7, 79.4, 79.3, 79.2, 77.4, 75.2, 75.0, 74.9,

74.8, 74.7, 74.6, 73.2, 68.3, 67.5, 67.4, 63.0, 55.8, 55.7,

38.0, 30.0, 29.9, 28.5, 28.1; ESI FT-MS: m/z (M+

Na)⁺calcd 1620.6043, obsd 1620.6079.

uum for 1 h, and dissolved in CH₂Cl₂(1 mL). The

solution was cooled to −20 °C, and TMSOTf (84 mL,

84 mmol, 1.0 M in CH₂Cl₂) was added. After 2 h, Et₃N

(100 mL) was added, the solution was concentrated in

vacuo, and the crude product was puriﬁed by ﬂash

silica gel chromatography (1:4 EtOAc–hexanes to yield

93 mg (81%) 35 as a white foam. [h]_D+19.5° (c 0.99,

n-Pentenyl 3,4-di-O-benzyl-2-deoxy-6-O-le6ulinyl-2-

phthalimido-i-D-glucopyranosyl-(16)-3,4-di-O-benz-

yl-2-deoxy-2-phthalimido-i-D-glucopyranosyl-(16)-

3,4-di-O-benzyl-2-deoxy-2-phthalimido-i-D-glucopy-

ranosyl - (16) - 3,4 - di - O - benzyl - 2 - deoxy - 2 - phthal-

imido-i-D-glucopyranoside (35).—Trisaccharide 34 (91

mg, 57 mmol) was dissolved in pyridine (0.60 mL) and

AcOH (0.40 mL) at 0 °C. Hydrazine monohydrate (15

mL, 0.29 mmol) was added, and the reaction mixture

was stirred for 1 h, then diluted with Et₂O (10 mL),

washed with HCl (10% in H₂O, 3×5 mL), H₂O, brine,

and dried over Na₂SO₄. After ﬁltration and concentra-

tion in vacuo, the crude product was puriﬁed by ﬂash

silica gel chromatography (2:3 EtOAc–hexanes) to

yield 85 mg (99%) of n-pentenyl 3,4-di-O-benzyl-2-de-

CH₂Cl₂); IR (thin ﬁlm): 1775, 1713, 1388, 1061 cm⁻¹

;

¹H NMR (500 MHz, CDCl₃) l 7.84–7.44 (m, 12H),

7.42–7.24 (m, 12H), 7.20–7.12 (m, 4H), 7.05–6.78 (m,

16H), 5.52–5.40 (m, 1H), 5.27 (d, J 8.5 Hz, 1H), 5.14

(d, J 8.2 Hz, 1H), 5.08 (d, J 8.2 Hz, 1H), 4.94 (d, J 8.2

Hz, 1H), 4.92 (d, J 10.7 Hz, 1H), 4.84 (d, J 12.2 Hz,

1H), 4.73–4.58 (m, 5H), 4.54 (d, J 10.7 Hz, 1H),

4.50–4.38 (m, 6H), 4.36–4.25 (m, 4H), 4.25–4.18 (m,

2H), 4.17–4.08 (m, 3H), 4.05 (dd, J 8.2, 10.7 Hz, 1H),

3.98 (d, J 10.4 Hz, 1H), 3.84 (d, J 9.8 Hz, 1H),

3.75–3.70 (m, 1H), 3.69–3.63 (m, 1H), 3.63–3.56 (m,

2H), 3.54–3.47 (m, 2H), 3.44–3.35 (m, 3H), 3.31–3.25

(m, 1H), 3.18–3.12 (m, 1H), 2.80–2.70 (m, 2H), 2.66–

2.58 (m, 2H), 2.20 (s, 3H), 1.75–1.63 (m, 2H), 1.40–

1.20 (m, 2H); ¹³C NMR (125 MHz, CDCl₃) l 206.6,

172.6, 168.8, 168.3, 138.1, 138.0, 137.9, 137.8, 137.7,

137.6, 134.0, 133.8, 131.5, 128.6 128.5, 128.4, 128.3,

128.3, 128.2, 128.1, 128.0, 127.9, 127.8, 127.5, 127.4,

127.3, 127.0, 126.9, 123.5, 123.3, 114.6, 98.1, 97.9, 97.8,

97.7, 79.7, 79.4, 79.3, 79.2, 79.1, 77.5, 75.2, 75.0, 74.9,

74.8, 74.7, 74.6, 73.1, 68.3, 67.7, 67.0, 66.9, 63.0, 55.9,

55.8, 55.6, 38.0, 30.0, 29.9, 28.4, 28.0, 23.6; ESI FT-MS:

m/z (M+2Na)²⁺calcd 1057.3812, obsd 1057.3797.

n-Pentenyl 3,4-di-O-benzyl-2-deoxy-6-O-le6ulinyl-2-

phthalimido-i-^D-glucopyranosyl-(16)-3,4-di-O-benz-

yl-2-deoxy-2-phthalimido-i-D - glucopyranosyl-(16)-

3,4-di-O-benzyl-2-deoxy-2-phthalimido-i-D-glucopyran-

osyl-(16)-3,4-di-O-benzyl- 2-deoxy-2-phthalimido-

i-^D-glucopyranosyl-(16)-3,4-di-O-benzyl-2-deoxy-2-

oxy-2-phthalimido-b-

O-benzyl-2-deoxy-2-phthalimido-b-

(16)-3,4-di-O-benzyl-2-deoxy-2-phthalimido-b-

D

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

D

-glucopyranosyl-

D-

glucopyranoside as a white foam. [h]_D+21.4° (c 0.90,

CH₂Cl₂); IR (thin ﬁlm): 3062, 1774, 1713, 1388, 1069

1

cm⁻¹; H NMR (500 MHz, CDCl₃) l 7.83–7.44 (m,

12H), 7.44–7.33 (m, 6H), 7.33–7.23 (m, 4H), 7.23–7.19

(m, 3H), 7.19–7.14 (m, 2H), 7.09–7.03 (m, 2H), 7.03–

6.99 (m, 2H), 6.99–6.94 (m, 2H), 6.94–6.90 (m, 2H),

6.90–6.78 (m, 9H), 5.56–5.46 (m, 1H), 5.35 (d, J 8.3

Hz, 1H), 5.19 (d, J 7.9 Hz, 1H), 4.98 (d, J 8.5 Hz, 1H),

4.91 (d, J 10.9 Hz, 1H), 4.83 (d, J 12.2 Hz, 1H), 4.78 (d,

J 10.9 Hz, 1H), 4.71 (d, J 10.8 Hz, 1H), 4.69 (d, J 11.9

Hz, 1H), 4.67 (d, J 12.2 Hz, 1H), 4.64 (ddd, J 1.5, 3.4,

17.1 Hz, 1H), 4.51 (d, J 10.7 Hz, 1H), 4.47 (d, J 11.9

Hz, 1H), 4.44–4.38 (m, 2H), 4.35 (d, J 5.5 Hz, 1H),

4.33–4.27 (m, 3H), 4.23 (dd, J 8.2, 10.9 Hz, 1H), 4.21

(dd, J 7.9, 14.9 Hz, 1H), 4.18 (dd, J 7.9, 10.7 Hz, 1H),

4.09 (d, J 10.4 Hz, 1H), 4.05 (dd, J 8.5, 10.9 Hz, 1H),

4.01–3.95 (m, 2H), 3.84 (dd, J 4.0, 11.3 Hz, 1H), 3.80

(t, J 8.9 Hz, 2H), 3.67–3.55 (m, 4H), 3.51 (dd, J 2.8, 9.8

Hz, 1H), 3.49–3.42 (m, 2H), 3.26–3.20 (m, 1H), 1.79–

1.67 (m, 2H), 1.43–1.24 (m, 2H); ¹³C NMR (125 MHz,

CDCl₃) l 168.2, 167.7, 138.1, 138.0, 137.9, 137.7, 137.6,

133.8, 131.6, 128.7, 128.6, 128.5, 128.4, 128.3, 128.2,

128.1, 128.0, 127.9, 127.8, 127.4, 127.1, 123.4, 114.6,

98.4, 98.3, 98.0, 79.6, 79.5, 79.3, 79.2, 79.1, 77.4, 75.7,

75.2, 74.9, 74.7, 74.6, 68.6, 68.0, 67.9, 61.7, 56.0, 55.8,

55.7, 29.9, 29.8, 28.5; ESI FT-MS: m/z (M+Na)⁺

calcd 1522.5675, obsd 1522.5802.

phthalimido-i-^D-glucopyranoside

(36).—Tetra-

saccharide 35 (81 mg, 39 mmol) was dissolved in pyri-

dine (0.60 mL) and AcOH (0.40 mL) at 0 °C.

Hydrazine monohydrate (10 mL, 0.20 mmol) was

added, and the reaction mixture was stirred for 1 h,

then diluted with Et₂O (10 mL), washed with HCl (10%

in H₂O, 3×5 mL), H₂O, brine, and dried over Na₂SO₄.

After ﬁltration and concentration in vacuo, the crude

product was puriﬁed by ﬂash silica gel chromatography

(2:3 EtOAc–hexanes) to yield 64 mg (83%) of n-pen-

tenyl

glucopyranosyl-(16)-3,4-di-O-benzyl-2-deoxy-2-ph-

thalimido-b- -glucopyranosyl-(16)-3,4-di-O-benzyl-

2-deoxy-2-phthalimido-b- -glucopyranosyl-(16)-3,4-

-glucopyran-

3,4-di-O-benzyl-2-deoxy-2-phthalimido-b-

D-

D

Glucosamine phosphate 10 (65.0 mg, 84 mmol) and

the n-pentenyl glucosamine acceptor, n-pentenyl 3,4-di-

di-O-benzyl-2-deoxy-2-phthalimido-b-

D

oside as a white foam. [h]_D+18.7° (c 1.03, CH₂Cl₂);

IR (thin ﬁlm): 1774, 1715, 1388, 1061 cm⁻¹; H NMR

1

O-benzyl-2-deoxy-2-phthalimido-b-

6)-3,4-di-O-benzyl-2-deoxy-2-phthalimido-b-

pyranosyl-(16)-3,4-di-O-benzyl-2-deoxy-2-phthal-

imido-b- -glucopyranoside (83 mg, 55 mmol) were

azeotroped with toluene (3×3 mL), dried under vac-

D-glucopyranosyl-(1

D-gluco-

(500 MHz, CDCl₃) l 7.81–7.45 (m, 16H), 7.43–7.19

(m, 18H), 7.18–7.13 (m, 4H), 7.09–7.05 (m, 2H), 7.03–

6.99 (m, 2H), 6.96–6.79 (m, 18H), 5.50–5.40 (m, 1H),

5.30 (d, J 8.5 Hz, 1H), 5.19 (d, J 8.2 Hz, 1H), 5.12 (d,

D

L.G. Melean et al. / Carbohydrate Research 337 (2002) 1893–1916

1915

J 8.2 Hz, 1H), 4.92 (d, J 8.5 Hz, 1H), 4.89 (d, J 11.0

Hz, 1H), 4.83 (d, J 12.2 Hz, 1H), 4.75 (d, J 11.0 Hz,

1H), 4.70–4.63 (m, 4H), 4.62–4.56 (m, 1H), 4.52–4.38

(m, 7H), 4.34–4.26 (m, 5H), 4.24–4.11 (m, 6H), 4.08–

3.94 (m, 4H), 3.89 (dd, J 1.5, 11.6 Hz, 1H), 3.82–3.76

(m, 3H), 3.72–3.64 (m, 2H), 3.62–3.55 (m, 3H), 3.53–

3.45 (m, 4H), 3.40–3.36 (m, 3H), 3.19–3.12 (m, 1H),

2.66–2.53 (m, 1H), 1.72–1.59 (m, 2H), 1.36–1.18 (m,

2H); ¹³C NMR (125 MHz, CDCl₃) l 168.3, 167.8,

138.1, 138.0, 137.8, 137.7, 133.8, 131.7, 128.6, 128.5,

128.4, 128.3, 128.2, 128.1, 128.0, 127.9, 127.5, 127.4,

127.1, 123.4, 114.6, 98.3, 97.9, 97.8, 79.8, 79.6, 79.5,

79.3, 79.1, 79.0, 75.6, 75.1, 75.0, 74.9, 74.7, 74.6, 68.4,

68.0, 67.7, 67.2, 61.7, 56.0, 55.9, 55.8, 55.7, 29.9, 28.5;

ESI FT-MS: m/z (M+Na)⁺calcd 1993.7357, obsd

1993.6614.

tomation. Glucosamine phosphate (5 equiv) was added,

as a solution in CH₂Cl₂(4 mL). After cooling to

−15 °C, TMSOTf (5 equiv, 0.125 M in CH₂Cl₂) was

added, the reaction mixture shaken for 30 min. The

reaction vessel was drained, and the resin was washed

with CH₂Cl₂(6×2 mL). A second quantity of glu-

cosamine phosphate (5 equiv was again added to the

reaction vessel as a solution in CH₂Cl₂, and the mixture

shaken an additional 30 min. The vessel was drained,

and the resin was washed again with CH₂Cl₂(6×2

mL).

General Procedure B. Automated clea6age of le6ulinyl

esters. The resin-bound saccharide (1 equiv) was

washed with THF (6×2 mL). Hydrazine monohydrate

(20 equiv, 0.5 M in 2:3 AcOH–Pyr.), was added, and

the reaction mixture shaken for 30 min at 15 °C. The

reaction vessel was drained, and the deprotection was

repeated by a second addition of hydrazine monohy-

drate (20 equiv), 0.5 M in 2:3 AcOH–Pyr.), and the

reaction mixture was shaken for 30 min. The reaction

vessel was drained, and the resin was washed with

AcOH–MeOH (0.2 M in THF, 6×2 mL), THF (6×2

mL), and CH₂Cl₂(6×2 mL).

Glucosamine phosphate 10 (38 mg, 49 mmol) and

tetrasaccharide acceptor n-pentenyl 3,4-di-O-benzyl-2-

deoxy-2-phthalimido-b-

di-O-benzyl-2-deoxy-2-phthalimido-b-

osyl-(16)-3,4-di-O-benzyl-2-deoxy-2-phthalimido-b-

-glucopyranosyl-(16)-3,4-di-O-benzyl-2-deoxy-2-

phthalimido-b- -glucopyranoside (63 mg, 32 mmol)

D

-glucopyranosyl-(16)-3,4-

D

-glucopyran-

D

were azeotroped with toluene (3×3 mL), dried under

vacuum for 1 h, and dissolved in CH₂Cl₂(1 mL). The

solution was cooled to −20 °C, and TMSOTf (49 mL,

49 mmol, 1.0 M in CH₂Cl₂) was added. After 2 h, Et₃N

(100 mL) was added, the solution was concentrated in

vacuo, and the crude product was puriﬁed by ﬂash

silica gel chromatography (1:4 EtOAc–hexanes) to

yield 70 mg (86%) of 36 as a white foam. [h]_D+29.4°

(c 0.78, CH₂Cl₂); IR (thin ﬁlm): 1775, 1714, 1388, 1066

General Procedure C. Clea6age of saccharides from

resin. The resin-bound saccharide (1 equiv) was placed

in a round-bottom ﬂask, and CH₂Cl₂(2 mL) was

added. Following addition of Grubbs’ catalyst (0.2

equiv), the suspension was stirred under an ethylene

atmosphere for 48 h. Tri(hydroxymethyl)phosphine (10

equiv) was added, and the solution was stirred until the

color turned yellow, then diluted with CH₂Cl₂(5 mL),

washed with H₂O (5×5 mL), brine, dried over

Na₂SO₄, ﬁltered and concentrated. Puriﬁcation by ﬂash

silica chromatography yielded the n-pentenyl

saccharide.

n-Pentenyl 3,4-di-O-benzyl-2-deoxy-6-O-le6ulinyl-2-

phthalimido-i-D-glucopyranosyl-(16)-3,4-di-O-benz-

yl-2-deoxy-2-phthalimido-i-D -glucopyranosyl-(16)-

3,4-di-O-benzyl-2-deoxy-2-phthalimido-i-D-glucopyran-

oside (34).—General Procedure A using functionalized

polystyrene resin 37 (25 mg, 1 mmol/g, 25 mmol) and

glucosamine phosphate 10 (97 mg, 125 mmol) was fol-

lowed by general Procedure B. The process was re-

peated three times, and then followed by general

Procedure C to afford 6 mg (17%) of 34, and 3 mg (9%)

of disaccharide 33. Analytical and NMR spectral data

matched those of the compounds made by solution-

phase synthesis.

1

cm⁻¹; H NMR (500 MHz, CDCl₃) l 7.84–7.44 (m,

20H), 7.44–6.98 (m, 30H), 6.97–6.75 (m, 20H), 5.45–

5.35 (m, 1H), 5.22 (d, J 8.2 Hz, 1H), 5.08 (d, J 8.2 Hz,

1H), 5.05 (d, J 8.2 Hz, 1H), 4.93 (d, J 8.2 Hz, 1H), 4.90

(d, J 8.9 Hz, 1H), 4.84 (d, J 12.2 Hz, 1H), 4.74–4.60

(m, 5H), 4.60–4.49 (m, 3H), 4.46 (d, J 11.9 Hz, 1H),

4.44–4.35 (m, 4H), 4.34–4.16 (m, 9H), 4.15–4.06 (m,

3H), 4.04–3.94 (m, 2H), 3.88 (d, J 10.4 Hz, 1H),

3.76–3.61 (m, 4H), 3.59–3.31 (m, 8H), 3.20–3.08 (m,

2H), 2.82–2.69 (m, 2H), 2.68–2.54 (m, 2H), 2.18 (s,

3H), 1.71–1.57 (m, 2H), 1.34–1.17 (m, 2H); ¹³C NMR

(125 MHz, CDCl₃) l 206.9, 172.9, 168.5, 168.0, 138.4,

138.3, 138.2, 138.1, 138.0, 134.4, 134.1, 131.8, 129.0,

128.9, 128.8, 128.7, 128.6, 128.5, 128.4, 128.3, 128.2,

128.1, 128.0, 127.9, 127.8, 127.7, 127.6, 127.3, 123.8,

114.8, 98.5, 98.3, 98.1, 98.0, 80.3, 80.0, 79.9, 79.8, 79.6,

79.4, 79.3, 77.4, 75.6, 75.5, 75.3, 75.2, 75.1, 75.0, 74.9,

74.8, 73.4, 68.6, 68.2, 67.5, 67.2, 66.8, 63.3, 56.2, 56.1,

38.3, 30.3, 30.2, 28.7, 28.4; ESI FT-MS: m/z (M+

Na)²⁺calcd 1292.9653, obsd 1292.9695.

Acknowledgements

Automated solid-phase synthesis.—General Procedure

A. Automated glycosylation using glucosamine phos-

phates. Octenediol functionalized resin (1 equiv) was

washed with CH₂Cl₂(6×2 mL) before beginning au-

Financial support from the donors of the Petroleum

Research Fund, administered by the ACS (ACS-PRF

34649-G1) for partial support of this research, the

Greenslaw Fellowship Fund (Graduate fellowship for

1916

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2001, 66, 8540–8548.

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c

1S10RR13886-01). Funding for the MIT-DCIT Mer-

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Article Doi

Toward the automated solid-phase synthesis of oligoglucosamines: Systematic evaluation of glycosyl phosphate and glycosyl trichloroacetimidate building blocks

DOI: 10.1016/S0008-6215(02)00299-9

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