Synthesis of monodeoxy and mono-O-methyl congeners of methyl β-d-mannopyranosyl-(1→2)-β-d-mannopyranoside for epitope mapping of anti-Candida albicans antibodies

Carbohydrate Research 344 (2009) 555–569

Contents lists available at ScienceDirect

Carbohydrate Research

journal homepage: w ww.elsevier.com/locate/carres

Synthesis of monodeoxy and mono-O-methyl congeners of methyl

b-^D-mannopyranosyl-(1?2)-b-D-mannopyranoside for epitope mapping of

anti-Candida albicans antibodies

*

Corwin M. Nycholat, David R. Bundle

Alberta Ingenuity Centre for Carbohydrate Science and Department of Chemistry, The University of Alberta, Gunning-Lemieux Chemistry Centre, Edmonton, AB, Canada T6G 2G2

a r t i c l e i n f o

a b s t r a c t

Article history:

A panel of six complementary monodeoxy and mono-O-methyl congeners of methyl b-D-mannopyrano-

Received 20 November 2008

Received in revised form 9 December 2008

Accepted 11 December 2008

Available online 24 December 2008

syl-(1?2)-b-D-mannopyranoside (1) were synthesized by stereoselective glycosylation of monodeoxy

and mono-O-methyl monosaccharide acceptors with a 2-O-acetyl-glucosyl trichloroacetimidate donor,

followed by a two-step oxidation–reduction sequence at C-2⁰. The b-manno conﬁguration of the ﬁnal

1

3

0

deprotected congeners 2–7 was conﬁrmed by measurement of J_C1,H1heteronuclear and J_{1 ,2}homonu-

clear coupling constants. These disaccharide derivatives will be used to map the epitope recognized by

a protective anti-Candida albicans monoclonal antibody C3.1 (IgG3) and to determine its key polar

contacts with the binding site.

Dedicated to Professor Dr. Hans Kamerling

on the occasion of his 65th birthday

Keywords:

Methyl b-D-mannopyranosyl-(1?2)-b-D-

mannopyranoside

Mono-deoxy and mono-O-methyl

congeners

Mapping of anti-Candida albicans antibodies

Functional group modiﬁcation

1. Introduction

Two monoclonal antibodies, an IgM (B6.1) and IgG (C3.1), raised

against the PMC in mice, were both found to protect against

Candida albicans, the causative agent of candidiasis, is a com-

mensal fungus that commonly inhabits the gastrointestinal tract,

oropharyngeal cavity and vulvovaginal tract of healthy humans.^1,2

However, risk of serious infection and occurrence of disease caused

by this opportunistic pathogen is increased in immunocompro-

mised patients and individuals undergoing long-term antibiotic

treatment or major invasive surgery. Therapeutics to combat infec-

tion have been limited to triazole derivatives and amphotericin B.³

However, the toxicity, emergence of resistance and costs of these

antifungal agents are potential problems and highlight the need

for alternative treatment strategies. The development of a vaccine

against Candida is attracting attention and appears to be a potential

subsequent infection.^8–10Interestingly, though the b-(1?2)-linked

mannan polymers vary in length from 1 to 7 residues, inhibition

assays revealed that both mAbs were speciﬁc for a di- or trisaccha-

ride. Furthermore, a novel pattern of antibody inhibition was

observedusing synthetic di-to hexasaccharidesof (1?2)-b-D-mann-

opyranans, where maximum activity was reached with di- and tri-

saccharides and diminished signiﬁcantly for larger structures.¹¹

This is in marked contrast to the paradigm elaborated by Kabat,

wherein larger dextran homo-oligomers up to a hexa- or heptasac-

charide exhibit increasing inhibitory activity with polyclonal anti-

bodies.¹²Beyond the unique size dependence of the two C. albicans

monoclonal antibodies described by Cutler and the conformational

analysis of the homo-oligosaccharides,⁹no additional structural data

are available for either the antibody or the antigenic determinant.

Knowledge of the recognition elements of the protective epitope

could provide important insights into the minimum-sized hapten

that might be employed in a synthetic conjugate vaccine.

A strategy of chemical mapping, devised by Lemieux, is used to

deﬁne the key polar contacts required for binding of the sugar to

the antibody.^13,14The relative activity of complementary monode-

oxy and mono-O-methyl analogues in combination with confor-

mational analysis helps to provide a three-dimensional model of

soluion.^4,5Whereas the

wall phosphomannan complex does not afford protective antibod-

ies, the relatively short b-(1?2) mannan oligosaccharides that are

attached to the a-mannan side chains are immunogenic and capa-

ble of raising protective antibodies. Consequently, antigens com-

posed of this epitope have become an attractive component of a

conjugate vaccine.^6,7

a-mannan component of the Candida cell

* Corresponding author. Tel.: +1 780 492 8808; fax: +1 780 492 7705.

E-mail address: dave.bundle@ualberta.ca (D.R. Bundle).

doi:10.1016/j.carres.2008.12.011

556

C. M. Nycholat, D. R. Bundle / Carbohydrate Research 344 (2009) 555–569

1

Oxidation of 12 by Me₂SO/Ac₂O¹⁷was followed by reduction

, R = R²= R³= OH

1

2

with L-Selectride^Òin THF at ꢀ78 °C to give 13. Lichtenthaler

et al.¹⁸investigated the reduction of 2-keto groups with various

hydride reagents and found L-Selectride^Òto reduce the carbonyl

of several substrates with high manno-selectivity. Conversely,

NaBH₄was found to be selective with only fully benzylated sub-

strates and gave poor manno- versus gluco-selectivity (7:1) with

benzylidene-containing substrates.¹⁵In our case, oxidation then

reduction of the benzylidene substrate 12 with L-Selectride^Ògave

the desired 3-deoxy mannose acceptor 13 in 83% yield (exclusively

HO

OH

O

1

, R = H, R²= R³= OH

3, R¹= OCH₃, R²= R³= OH

4, R²= H, R¹= R³= OH

O

HO

R³

5, R²= OCH₃, R¹= R³= OH

R²

O

3

, R = H, R¹= R²= OH

6

7

R¹

OMe

3

, R = OCH₃, R¹= R²= OH

Figure 1. Native disaccharide 1 and the corresponding target deoxy and O-methyl

congeners 2–7.

3

manno); the observed J_1,21.3 Hz for the product when compared

the topography of the oligosaccharide epitope. To investigate in

further detail the size and topology of the mAb IgG3 (C3.1) anti-

body binding site, a panel of six monodeoxy and mono-O-methyl

to that of compound 12 indicated b-manno stereochemistry. A

small amount of side product (usually 5–10%) was obtained and

identiﬁed as methyl 4,6-O-benzylidene-3-deoxy-2-O-methylthi-

congeners 2–7 of the disaccharide methyl b-D-mannopyranosyl-

omethyl-b-D-glucopyranoside. It has previously been noted that

(1?2)-b- -mannopyranoside (1) have been synthesized. For each

D

the methylthiomethyl ether substituted by-product is formed

under Me₂SO/Ac₂O oxidation conditions.¹⁷

congener, a single hydroxyl group on the reducing end residue

of the parent disaccharide 1 has been modiﬁed by either deoxy-

genation or methylation (Fig. 1).

The 3-O-methyl mannose acceptor 15 was prepared by direct

methylation of methyl 4,6-O-benzylidene-b-D-glucopyranoside

(8) using stannylidene chemistry (Scheme 1). Reaction with dibu-

tyltin oxide in toluene at reﬂux, followed by treatment with

methyl iodide in DMF, gave 14 in 71% yield. The gluco-intermediate

14 was then reacted following the standard oxidation–reduction

sequence to afford the 3-O-methyl mannose acceptor 15 in 80%

yield. The measured J_1,2coupling constant (1.0 Hz) indicated

inversion to the b-manno-conﬁguration.

Glycosylation of the prepared 3-deoxy and 3-O-methyl acceptors

13 and 15, with 2-O-acetyl-3,4,6-tri-O-benzyl-b-D-glucopyranosyl

2. Results and discussion

2.1. Synthesis of 3-deoxy and 3-O-methyl disaccharides 2 and 3

3

As illustrated in Scheme 1, the 3-deoxy and 3-O-methyl

acceptors 13 and 15 were readily available from methyl 4,6-O-

benzylidene-b-

phase-transfer conditions¹⁶with p-methoxybenzyl chloride gave

mixture of 2-O- and 3-O-monobenzylated regioisomers.

D

-glucopyranoside (8).¹⁵Initial reaction of 8 under

trichloroacetimidate¹⁹donor 16, gave intermediate disaccharides

17 (59% yield) and 20 (97% yield), respectively (Scheme 2). The

synthesis of 17 was not optimized. Transesteriﬁcation followed by

the standard two-step oxidation–reduction sequence converted

disaccharides 17 and 20 to intermediates 19 and 22. For all oxida-

tion–reduction sequences performed at C-2⁰described in this paper,

a

Although the desired 2-O-p-methoxybenzyl intermediate 9 was

obtained in lower yield (30% yield), reaction scale-up provided

sufﬁcient quantities to proceed. Temporary protection of the 2-

hydroxyl as the p-methoxybenzyl ether allowed for straightfor-

ward manipulation of the 3-hydroxyl group. The regiochemistry

of 9 was conﬁrmed by subsequent reaction with thiocarbonyl

diimidazole in toluene at 80 °C to give 10 in 64% yield, in which

the chemical shift of H-3 moved downﬁeld from d 3.82 to

6.11 ppm. The Barton–McCombie substrate 10 was then treated

with tributyltin hydride in the presence of AIBN to afford the

3-deoxy intermediate 11 in 78% yield. Removal of the p-

methoxybenzyl ether with DDQ in wet CH₂Cl₂gave 12 in 86%

yield and exposed the 2-hydroxyl group, which was then in-

verted from the gluco to the manno conﬁguration via a standard

two-step oxidation–reduction sequence.

the inversion of stereochemistry was monitored by comparison of

3

0

the J_{1 ,2}coupling constants preceding and following the two-step

sequence. Typically, ³J_1,2coupling for b-gluco structures is between

8 and 10 Hz and for b-manno <1 Hz. For compounds 18 and 21, the

3

0

J_{1 ,2}coupling constants measured 8.0 Hz, while the J_{1 ,2}proton

coupling constants measured 0.8 Hz for both 19 and 22, indicating

inversion from b-gluco to b-manno stereochemistry. Global debenzy-

lation by hydrogenolysis afforded the desired 3-deoxy 2 and 3-O-

methyl 3 target analogues in 75% and 74% yields, respectively. The

b-manno conﬁgurations of the ﬁnal deprotected analogues

Ph

O

Ph

O

a

d

O

OMe

OPMB

OMe

HO

R

OH

8

12

9

, R = OH

b

e

10, R = C(S)Im

11, R = H

f

c

Ph

O

OH

O

OMe

O

MeO

OMe

OH

14

13

f

OH

O

Ph

O

OMe

MeO

15

Scheme 1. Reagents and conditions: (a) PMBCl, CH₂Cl₂, n-Bu₄NHSO₄, 5% aq NaOH, 30%; (b) 1,1⁰-thiocarbonyldiimidazole, toluene, 64%; (c) n-Bu₃SnH, AIBN, toluene, 78%; (d)

DDQ, CH₂Cl₂, H₂O, 86%; (e) n-Bu₂SnO, toluene, then MeI, DMF, 71%; (f) Me₂SO, Ac₂O, then L-Selectride, THF, ꢀ78 °C, 83% over two steps.

C. M. Nycholat, D. R. Bundle / Carbohydrate Research 344 (2009) 555–569

557

BnO

17

, R = OAc

O

R

BnO

c

O

BnO

18, R = OH (gluco)

19, R = OH (manno)

a

b

e

d

2

3

Ph

O

BnO

O

OMe

O

R

BnO

OAc

BnO

16

20, R = OAc

, R= OC(NH)CCl₃

O

R

BnO

c

O

BnO

Ph

21, R = OH (gluco)

d

22

, R = OH (manno)

O

OMe

MeO

Scheme 2. Reagents and conditions: (a) 13, TMSOTf, CH₂Cl₂, 0 °C, 59%; (b) 15, TMSOTf, CH₂Cl₂, 0 °C, 97%; (c) NaOCH₃, CH₃OH, quant. (for 18), 88% (for 21); (d) Me₂SO, Ac₂O,

then L-Selectride, THF, ꢀ78 °C, 65% (for 19 over two steps), 72% (for 22 over two steps); (e) H₂, Pd/C, CH₃OH, CH₂Cl₂, 75% (for 2), 74% (for 3).

OR

O

BnO

OBz

O

Ph

a

O

b

O

R

OMe

BnO

23

BnO

e

, R = OH

25

29

, R = OMe

, R = OH

c

24, R = OBz

26, R = C(S)Im

27, R = H

d

f

BnO

MeO

BnO

OH

O

OH

O

OMe

28

30

Scheme 3. Reagents and conditions: (a) BzCl, pyridine, quant.; (b) NaCNBH₃, HCl, Et₂O, 81%; (c) 1,1⁰-thiocarbonyldiimidazole, toluene, 60%; (d) n-Bu₃SnH, AIBN, toluene, 68%;

(e) MeI, NaH, DMF, 0 °C then AcOH, 97%; (f) NaOCH₃, CH₃OH, 89% (for 28), 95% (for 30).

describedinthispaperwereconﬁrmedby¹J_C1,H1heteronuclear²⁰and

standard oxidation–reduction sequence to provide intermediates

33 and 36. Subsequent hydrogenolysis then afforded the 4-deoxy

4 (52% yield) and 4-O-methyl 5 (88% yield) disaccharide analogues,

3

J_{1 ,2}homonuclear coupling constants. In all cases, the ¹J_C1,H1values

0

were between 160 and 164 Hz, and the ³J_{1 ,2}values were <1 Hz.

2.2. Synthesis of 4-deoxy and 4-O-methyl disaccharides 4 and 5

The fully protected intermediate 24 obtained from benzoylation

0

respectively. The ¹J_C1,H1and ³J_{1 ,2}coupling constants conﬁrmed the

b-manno conﬁgurations of both 4 and 5.

0

2.3. Synthesis of 6-deoxy and 6-O-methyl disaccharides 6 and 7

of methyl 3-O-benzyl-4,6-O-benzylidene-b-D-mannopyranoside

(23)¹⁵provided a convenient strategy for accessing and modifying

the C-4 hydroxyl group, while allowing temporary protection of

the C-2 hydroxyl (Scheme 3). Regioselective reductive opening of

the benzylidene acetal with sodium cyanoborohydride and HCl in

ether²¹gave 25 in 81% yield and allowed for straightforward mod-

iﬁcation at C-4. The regioselectivity was conﬁrmed by subsequent

reaction of the hydroxyl with thiocarbonyl diimidazole in toluene

at reﬂux to give 26 (60% yield), in which the chemical shift of H-

4 moved downﬁeld from d 4.04 to 6.24. Treatment of the Barton–

McCombie substrate with tributyltin hydride in the presence of

AIBN gave the 4-deoxy substrate 27. The temporary benzoyl group

was removed by transesteriﬁcation using sodium methoxide in

methanol to give the 4-deoxy acceptor 28.

Reductive benzylidene acetal opening of methyl 3-O-benzyl-

4,6-O-benzylidene-b-D

-glucopyranoside (37)¹⁵under anhydrous

conditions with BH₃ꢁTHF and dibutylboron triﬂate²²gave diol 38

in 83% yield (Scheme 5). Controlled reaction of the C-6 primary

hydroxyl with methanesulfonyl chloride in pyridine gave interme-

diate 39 (66% yield). The downﬁeld shift of the C-6 proton reso-

nances (from d 3.89 and 3.75 to d 4.47 and 4.37) conﬁrmed the

regioselectivity of both the benzylidene acetal opening and selec-

tive sulfonylation. The 6-deoxy intermediate 40 was obtained in

80% yield by reductive displacement of the sulfonate using NaBH₄.

The standard two-step oxidation–reduction sequence was then

used to invert the gluco-conﬁguration to yield the desired 6-deoxy

3

mannose acceptor 41 (88% yield). The change in the J_1,2coupling

Methylation of intermediate 25 using methyl iodide and

sodium hydride, followed by quenching with acetic acid, gave

intermediate 29 (Scheme 3). Transesteriﬁcation of the benzoyl

group afforded the desired 4-O-methyl acceptor 30 in 95% yield.

Glycosylation of 28 and 30 with benzylated trichloroacetimi-

date¹⁹donor 16 under TMSOTf activation gave disaccharides 31

(83% yield) and 34 (97% yield), respectively (Scheme 4). The disac-

charides were then treated with NaOCH₃–CH₃OH, followed by the

constant (from 7.6 to 1.1 Hz) indicated inversion to the b-manno

conﬁguration.

Reductive benzylidene acetal opening of methyl 2-O-benzoyl-3-

O-benzyl-4,6-O-benzylidene-b- -glucopyranoside (42)²³under

anhydrous conditions with BH₃ꢁ^DTHF and dibutylboron triﬂate²²gave

43 in 80% yield (Scheme 6). Methylation of the free C-6 hydroxyl

group afforded 44, which was subsequently reacted under Zemplén

conditions to provide intermediate 45 (86% yield two steps). Again,

558

C. M. Nycholat, D. R. Bundle / Carbohydrate Research 344 (2009) 555–569

BnO

O

R

BnO

31

, R = OAc

32, R = OH (gluco)

33

O

BnO

c

a

b

BnO

e

d

, R = OH (manno)

4

5

O

BnO

OMe

O

R

BnO

OAc

O

34, R = OAc

16

, R= OC(NH)CCl₃

O

BnO

c

R

35, R = OH (gluco)

BnO

MeO

d

36

, R = OH (manno)

O

OMe

BnO

Scheme 4. Reagents and conditions: (a) 28, TMSOTf, CH₂Cl₂, 0 °C, 83%; (b) 30, TMSOTf, CH₂Cl₂, 0 °C, 97%; (c) NaOCH₃, CH₃OH, 78% (for 32), 97% (for 35); (d) Me₂SO, Ac₂O, then

L-Selectride, THF, ꢀ78 °C, 65% (for 33 over two steps), 61% (for 36 over two steps); (e) H₂, Pd/C, CH₃OH, CH₂Cl₂, 52% (for 4), 88% (for 5).

Ph

HO

BnO

MsO

BnO

O

a

b

O

OMe

BnO

OMe

BnO

OH

37

38

39

41

OH

O

d

c

O

BnO

OMe

OH

40

Scheme 5. Reagents and conditions: (a) BH₃ꢁTHF, n-Bu₂BOTf, CH₂Cl₂, 0 °C, 83%; (b) MsCl, pyridine, 0 °C, 66%; (c) NaBH₄, DMF, 80 °C, 80%; (d) Me₂SO, Ac₂O, then L-Selectride,

THF, ꢀ78 °C °C, 88%.

MeO

BnO

HO

BnO

Ph

O

a

c

b

d

O

OMe

BnO

OMe

BnO

OBz

44

46

42

43

45

MeO

BnO

MeO

BnO

OH

O

BnO

OMe

BnO

OH

Scheme 6. Reagents and conditions: (a) BH₃ꢁTHF, n-Bu₂BOTf, CH₂Cl₂, 0 °C, 80%; (b) MeI, NaH, DMF, 0 °C, then AcOH, 96%; (c) NaOCH₃, CH₃OH, 90%; (d) Me₂SO, Ac₂O, then L-

Selectride, THF, ꢀ78 °C, 85%.

BnO

O

R

BnO

47

, R = OAc

48, R = OH (gluco)

49

O

BnO

c

a

b

e

d

, R = OH (manno)

6

7

O

BnO

OMe

O

R

BnO

OAc

O

R

MeO

BnO

16, R= OC(NH)CCl₃

O

BnO

50, R = OAc

c

51, R = OH (gluco)

e

d

52

, R = OH (manno)

O

OMe

BnO

Scheme 7. Reagents and conditions: (a) 41, TMSOTf, CH₂Cl₂, 0 °C, 96%; (b) 46, TMSOTf, CH₂Cl₂, 0 °C, 68%; (c) NaOCH₃, CH₃OH, quant. (for 48), 96% (for 51); (d) Me₂SO, Ac₂O,

then L-Selectride, THF, ꢀ78 °C, 82% (for 49 over two steps), 78% (for 52 over two steps); (e) H₂, Pd/C, CH₃OH, CH₂Cl₂, 86% (for 6), 69% (for 7).

the standard two-step oxidation–reduction sequence was used to

give the desired 6-O-methyl mannose acceptor 46 (85% yield). The

change in the ³J_1,2coupling constant (from 7.6 to 1.0 Hz) indicated

inversion to the b-manno conﬁguration.

Reaction of the 6-deoxy 41 and 6-O-methyl 46 acceptors with

benzylated trichloroacetimidate¹⁹donor 16 under TMSOTf activa-

tion gave disaccharides 47 (96% yield) and 50 (68% yield), respec-

tively (Scheme 7). The disaccharides were then treated with

C. M. Nycholat, D. R. Bundle / Carbohydrate Research 344 (2009) 555–569

559

0

NaOCH₃–CH₃OH followed by the oxidation–reduction sequence to

provide intermediates 49 and 52. Subsequent hydrogenolysis of 49

and 52 gave the desired 6-deoxy 6 (86% yield) and 6-O-methyl 7

D₂O) d 4.78 (d, 1H, J_{1 ,2}0.8 Hz, H-1⁰), 4.63 (d, 1H, J_1,21.2 Hz, H-1),

4.14 (m, 1H, H-2), 4.05 (dd, 1H, J_{1 ,2}0.8, J_{2 ,3}3.3 Hz, H-2⁰), 3.92

0

(dd, 1H, J_{5 ,6}2.3, J_gem12.3 Hz, H-6a⁰), 3.91 (dd, 1H, J_5,62.7, J_gem

12.2 Hz, H-6a), 3.83 (ddd, 1H, J_3,44.7, 11.0, J_4,59.6 Hz, H-4), 3.73

0

1

(69% yield) disaccharide analogues, respectively. The J_C1,H1and

3

0

J_{1 ,2}coupling constants conﬁrmed the b-manno conﬁguration for

both 6 and 7.

(dd, 1H, J_{5 ,6}6.5, J_gem12.3 Hz, H-6b⁰), 3.72 (dd, 1H, J_5,66.8, J_gem

12.2 Hz, H-6b), 3.63 (dd, 1H, J_{2 ,3}3.3, J_{3 ,4}9.6 Hz, H-3⁰), 3.56 (dd,

0

1H, J_{3 ,4}ꢂ J_{4 ,5}9.6 Hz, H-4⁰), 3.53 (s, 3H, CH₃O), 3.50 (ddd, 1H, J_4,5

0

2.4. Conclusion

9.3, J_5,62.7, 6.8 Hz, H-5), 3.35 (ddd, 1H, J_{4 ,5}9.6, J_{5 ,6}2.3, 6.5 Hz,

H-5⁰), 2.41 (ddd, 1H, J_2,3ꢂ J_3,44.3, J_gem13.6 Hz, H-3eq), 1.72 (ddd,

1H, J_2,32.9, J_gem13.6, J_3,411.1 Hz, H-3ax); ¹³C NMR (125 MHz,

In conclusion, a panel of six complementary deoxy and O-

methyl analogues (2–7) modiﬁed on the reducing-end residue

1

D₂O)

d

102.9 (C-1, J_C1,H1160.3 Hz, b), 101.8 (C-1⁰, J_{C1 ,H1}

0

(C-3, C-4 and C-6) of methyl b-

D

-mannopyranosyl-(1?2)-b-

D

-man-

160.6 Hz, b), 80.9 (C-5), 77.1 (C-5⁰), 75.7 (C-2), 73.7 (C-3⁰), 71.3

(C-2⁰), 67.7 (C-4⁰), 63.1 (C-4), 62.2, 62.0 (C-6⁰, C-6), 57.6 (CH₃O),

36.9 (C-3); HRESIMS: Calcd for C₁₃H₂₄O₁₀Na 363.1262. Found

363.1264.

nopyranoside (1) have been synthesized. All deoxygenations and

O-methylations were performed at the monosaccharide level pro-

ducing six modiﬁed acceptors. The synthesis of the challenging

(1?2)-b-D-manno linkage was approached by initial highly b-ster-

eoselective glucosylation employing a common trichloroacetimi-

date donor capable of neighbouring group participation, followed

by a two-step oxidation–reduction sequence at C-2⁰. The b-manno

conﬁgurations of the ﬁnal deprotected analogues were conﬁrmed

3.3. Methyl b-

mannopyranoside (3)

D-mannopyranosyl-(1?2)-3-O-methyl-b-D-

Compound 22 (50.7 mg, 0.070 mmol) was dissolved in 1:1

CH₂Cl₂–CH₃OH (10 mL) and stirred with 10% Pd/C (50 mg) under

an H₂atmosphere, then processed as described for 2. Filtration,

then lyophilization, gave 3 (19.1 mg, 74%) as a clear glass: R_f0.23

1

3

0

by measurement of J_C1,H1heteronuclear and J_{1 ,2}homonuclear

coupling constants. These ﬁnal structures will serve as valuable

tools to probe the key polar contacts involved in the binding of

the protective anti-C. albicans mAb C3.1 (IgG3).^8–11

(6.0:3.5:0.5, CH₂Cl₂–MeOH–H₂O); [

a

]

D

ꢀ86 (c 0.37, H₂O); ¹H

NMR (500 MHz, D₂O) d 4.83 (s, 1H, H-1⁰), 4.60 (s, 1H, H-1), 4.52

(d, 1H, J_2,33.1 Hz, H-2), 4.09 (d, 1H, J_{2 ,3}1.8 Hz, H-2⁰), 3.93 (dd,

0

3. Experimental

1H, J_5,62.0, J_gem12.3 Hz, H-6a), 3.93 (dd, 1H, J_{5 ,6}1.8, J_gem12.2 Hz,

H-6a⁰), 3.77 (dd, 1H, J_{5 ,6}5.8, J_gem12.2 Hz, H-6b⁰), 3.74 (dd, 1H,

J_5,66.5, J_gem12.3 Hz, H-6b), 3.64 (dd, 1H, J_3,4ꢂ J_4,59.9 Hz, H-4),

3.58-3.64 (m, 2H, H-3⁰, H-4⁰), 3.54 (s, 3H, CH₃O), 3.49 (s, 3H,

CH₃O), 3.41 (ddd, 1H, J_4,59.2, J_5,62.2, 6.5 Hz, H-5), 3.38 (dd, 1H,

0

3.1. General methods

All chemical reagents were of analytical grade and used as

obtained from commercial sources unless otherwise indicated. Sol-

vents used in water-sensitive reactions were puriﬁed by successive

passage through columns of alumina and copper under nitrogen,

except for DMSO, which was distilled under vacuum and collected

over 4 Å molecular sieves. Unless otherwise noted, reactions were

carried out at room temperature, and water-sensitive reactions

were performed under an atmosphere of argon. Molecular sieves

were ﬂame dried and then allowed to cool to room temperature

under argon before use. Reactions were monitored by analytical

thin-layer chromatography (TLC) performed on Silica Gel 60-F₂₅₄

(E. Merck). Plates were visualized under UV light, and/or by treat-

ment with 5% sulfuric acid in ethanol followed by heating. Organic

solvents were removed under vacuum at <40 °C. Medium-pressure

chromatography was conducted using silica gel (230–400 mesh,

Silicycle, Montreal) at ﬂow rates between 5 and 10 mL min^ꢀ1. Fol-

lowing deprotection, ﬁnal compounds were passed through an All-

tech Carbograph ﬁlter and then lyophilized. ¹H NMR spectra were

recorded at 500 or 600 MHz, and chemical shifts, reported in d

(ppm), were referenced to internal residual protonated solvent sig-

nals or to external acetone (0.1% ext. acetone @ d 2.225 ppm) in the

case of D₂O. ¹³C NMR spectra were recorded at 125 MHz, and

chemical shifts are referenced to internal CDCl₃(d 77.23) or exter-

nal acetone (d 31.07).

0

J_2,33.1, J_3,49.8 Hz, H-3), 3.34 (ddd, 1H, J_{4 ,5}9.5, J_{5 ,6}2.2, 5.8 Hz,

H-5⁰); ¹³C NMR (125 MHz, D₂O) d 102.6 (C-1, J_C1,H1158.5 Hz, b),

1

101.4 (C-1⁰, J_{C1 ,H1}164.1 Hz, b), 82.2 (C-3), 77.3, 77.0 (C-5, C-5⁰),

73.9, 73.6 (C-2, C-4⁰), 71.3 (C-2⁰), 67.5, 66.7 (C-4, C-3⁰), 62.0, 61.9

(C-6, C-6⁰), 58.0 (CH₃O-C1), 57.2 (CH₃O-C3); HRESIMS: Calcd for

C₁₄H₂₆O₁₁Na 393.1367. Found 393.1366.

0

3.4. Methyl b-D-mannopyranosyl-(1?2)-4-deoxy-b-D-lyxo-

hexopyranoside (4)

Compound 33 (49.1 mg, 0.062 mmol) was dissolved in 1:1

CH₂Cl₂–CH₃OH (10 mL) and stirred with 10% Pd/C (50 mg) under

an H₂atmosphere, then processed as described for 2. Filtration,

then lyophilization, gave 4 (11.0 mg, 52%) as a clear glass: R_f0.27

(6:3.5:0.5, CH₂Cl₂–CH₃OH–H₂O); [

a

]

ꢀ60 (c 0.58, H₂O); ¹H NMR

D

(500 MHz, D₂O) d 4.83 (s, 1H, H-1⁰), 4.51 (s, 1H, H-1), 4.12–4.13

(m, 2H, H-2⁰, H-2), 3.92 (dd, 1H, J_{5 ,6}2.3, J_gem12.3 Hz, H-6a⁰), 3.88

(ddd, 1H, J_2,33.0, J_3,4eq5.0, J_3,4ax12.1 Hz, H-3) 3.63–3.73 (m, 5H,

0

H-3⁰, H-6b⁰, H-5, H-6a, H-6b) 3.55 (dd, 1H, J_{3 ,4}ꢂ J_{4 ,5}9.8, H-4⁰),

0

3.54 (s, 3H, CH₃O), 3.36 (ddd, 1H, J_{5 ,6b}6.8 Hz, H-5⁰), 1.71 (ddd,

1H, J_gem12.6, J_4,50.8 Hz, H-4eq), 1.55 (ddd, 1H, J_4ax,512.2 Hz, H-

0

4ax); ¹³C NMR (125 MHz, D₂O) d 102.7 (C-1, J_C1,H1159.4 Hz, b),

1

101.3 (C-1⁰, J_{C1 ,H1}162.4 Hz, b), 77.4 (C-2), 77.2 (C-5⁰), 74.0, 73.7

(C-3⁰, C-5), 71.3 (C-2⁰), 68.3 (C-3), 67.7 (C-4⁰), 64.6 (C-6), 62.0 (C-

6⁰), 57.8 (CH₃O), 30.7 (C-4); HRESIMS: Calcd for C₁₃H₂₄O₁₀Na

363.1262. Found 363.1261.

0

3.2. Methyl b-

D-mannopyranosyl-(1?2)-3-deoxy-b-D-arabino-

hexopyranoside (2)

Compound 19 (49.0 mg, 0.070 mmol) was dissolved in 1:1

CH₂Cl₂–MeOH (10 mL) and stirred with 10% Pd/C (50 mg) under

an H₂atmosphere. The catalyst was separated by ﬁltration through

3.5. Methyl b-

mannopyranoside (5)

D-mannopyranosyl-(1?2)-4-O-methyl-b-D-

a Whatman membrane (0.45 lm, PVDF), and the ﬁltrate was con-

Compound 36 (51.8 mg, 0.063 mmol) was dissolved in 1:1

CH₂Cl₂–MeOH (10 mL) and stirred with 10% Pd/C (50 mg) under

an H₂atmosphere, then processed as described for 2. Filtration,

then lyophilization, gave 5 (20.4 mg, 88%) as a clear glass: R_f0.48

centrated under reduced pressure. The residue was redissolved in

H₂O, passed through an Alltech Carbograph ﬁlter and then lyophi-

lized to yield 2 (17.8 mg, 75%) as a clear glass: R_f0.25 (6:3.5:0.5,

ꢀ33 (c 0.27, H₂O); ¹H NMR (500 MHz,

(6:3.5:0.5, CH₂Cl₂–MeOH–H₂O); [a]

ꢀ56 (c 0.50, H₂O); ¹H NMR

CH₂Cl₂–CH₃OH–H₂O); [

a

]

D

560

C. M. Nycholat, D. R. Bundle / Carbohydrate Research 344 (2009) 555–569

(500 MHz, D₂O) d 4.82 (s, 1H, H-1⁰), 4.61 (s, 1H, H-1), 4.23 (d, 1H,

derivative 9 (1.28 g, 30%) and the 3-O-(4-methoxybenzyl) deriva-

tive (1.93 g, 45%) both as white solids; 9: R_f0.48 (1:1 hexanes–

J_2,33.2Hz, H-2), 4.12 (d, 1H, J_{2 ,3}3.3 Hz, H-2⁰), 3.91–3.93 (m, 2H,

0

H-6a⁰, H-6a), 3.71–3.77 (m, 3H, H-6b⁰, H-3, H-6b), 3.63 (ddd, 1H,

EtOAc); [

a

]

D

ꢀ18 (c 0.73, CHCl₃); ¹H NMR (600 MHz, CDCl₃) d

J_{2 ,3}0.9, J_{3 ,4}9.7 Hz, H-3⁰), 3.56 (dd, 1H, J_{3 ,4}ꢂ J_{4 ,5}9.7 Hz, H-4⁰),

7.48–7.50 (m, 2H, ArH), 7.30–7.38 (m, 5H, ArH), 6.89–6.91 (m,

2H, ArH), 5.53 (s, 1H, PhCHO₂), 4.86 (d, 1H, J_gem11.1Hz, PhCH₂O),

4.66 (d, 1H, PhCH₂O), 4.43 (d, 1H, J_1,27.7 Hz, H-1), 4.35 (dd, 1H,

J_5,64.9, J_gem10.4 Hz, H-6a), 3.82 (dd, 1H, J_2,3ꢂ J_3,49.1 Hz, H-3),

3.81 (s, 3H, CH₃O), 3.78 (dd, 1H, J_5,6ꢂ J_gem10.3 Hz, H-6b), 3.60 (s,

3H, CH₃O), 3.53 (dd, 1H, J_3,4ꢂ J_4,59.3 Hz, H-4), 3.42 (ddd, 1H, J_4,5

9.7, J_5,65.1, 9.7 Hz, H-5), 3.32 (dd, 1H, J_1,27.8, J_2,38.9 Hz, H-2);

¹³C NMR (125 MHz, CDCl₃) d 159.4 (Ar), 137.0 (Ar), 130.3 (Ar),

129.8 (Ar), 129.2 (Ar), 128.3 (Ar), 126.3 (Ar), 114.0 (Ar), 105.0

(C-1), 101.8 (PhCHO₂), 81.4 (C-2), 80.5 (C-4), 74.3 (PhCH₂O), 73.1

(C-3), 68.7 (C-6), 66.1 (C-5), 57.4 (CH₃O), 55.3 (CH₃O); HRESIMS:

Calcd for C₂₂H₂₆O₇Na 425.1571. Found 425.1570.

0

3.53 (s, 6H, CH₃OC-1, CH₃OC-4), 3.34–3.39 (m, 3H, H-5⁰, H-4, H-

1

5); ¹³C NMR (125 MHz, D₂O) d 102.2 (C-1, J_C1,H1159.7Hz, b),

1

101.3 (C-1⁰, J_{C1 ,H1}162.7 Hz, b), 78.7 (C-2), 78.0 (C-4), 77.2 (C-5⁰),

76.3 (C-5), 73.7 (C-3⁰), 73.0 (C-3), 71.2 (C-2⁰), 67.7 (C-4⁰), 62.0,

61.5 (C-6⁰, C-6), 61.1 (CH₃OC-4), 58.0 (CH₃OC-1); HRESIMS: Calcd

for C₁₄H₂₆O₁₁Na 393.1367. Found 393.1366.

0

3.6. Methyl b-D-mannopyranosyl-(1?2)-6-deoxy-b-D-

mannopyranoside (6)

Compound 49 (55.0 mg, 0.070 mmol) was dissolved in 1:1

CH₂Cl₂–MeOH (10 mL) then stirred with 10% Pd/C (50 mg) under

an H₂atmosphere, then processed as described for 2. Filtration,

then lyophilization, gave 6 (20.4 mg, 86%) as a clear glass: R_f0.49

3.9. Methyl 4,6-O-benzylidene-2-O-(4-methoxybenzyl)-3-O-

thiocarbonylimidazole-b-D-glucopyranoside (10)

(6:3.5:0.5, CH₂Cl₂–MeOH–H₂O); [

a

]

ꢀ45 (c 1.1, H₂O); ¹H NMR

D

(600 MHz, D₂O) d 4.82 (s, 1H, H-1⁰), 4.61 (s, 1H, H-1), 4.24 (d, 1H,

The 2-O-(4-methoxybenzyl) derivative 9 (1.20 g, 2.98 mmol)

was dissolved in dry toluene (20 mL). 1,1⁰-Thiocarbonyldiimidaz-

ole (1.06 g, 5.96 mmol) was added, and the reaction was stirred

at reﬂux under argon overnight. The reaction mixture was cooled,

then concentrated under reduced pressure. The black oily residue

was subjected to chromatography on silica gel (7:3 hexanes–

EtOAc) to give the Barton–McCombie substrate 10 (978 mg, 64%)

J_2,33.3 Hz, H-2), 4.10 (d, 1H, J_{2 ,3}3.3 Hz, H-2⁰), 3.92 (dd, 1H, J_{5 ,6}

0

2.3, J_gem12.3 Hz, H-6a⁰), 3.73 (dd, 1H, J_{5 ,6}6.8, J_gem12.3 Hz, H-

0

6b⁰), 3.63 (dd, 1H, J_{2 ,3}3.3, J_{3 ,4}9.3Hz, H-3⁰), 3.58 (dd, 1H, J_2,33.3,

0

J_3,49.3 Hz, H-3) 3.55 (dd, 1H, J_{3 ,4}ꢂ J_{4 ,5}9.7 Hz, H-4⁰), 3.51 (s, 3H,

0

CH₃O), 3.34–3.42 (m, 3H, H-5⁰, H-4, H-5), 1.32 (d, 3H, J_5,65.6 Hz,

CH₃); ¹³C NMR (125 MHz, D₂O) d 102.1 (C-1, J_C1,H1152.3 Hz, b),

1

101.3 (C-1⁰, J_{C1 ,H1}162.7 Hz, b), 78.6 (C-2), 77.2 (C-5⁰), 73.7, 73.4,

73.2, 72.9 (C-3⁰, C-3, C-4, C-5), 71.2 (C-2⁰), 67.7 (C-4⁰), 62.0 (C-6⁰),

57.9 (CH₃O), 17.5 (C-6); HRESIMS: Calcd for C₁₃H₂₄O₁₀Na

363.1262. Found 363.1261.

as a white solid: R_f0.24 (1:1 hexanes–EtOAc); [a] +10 (c 0.84,

0

D

CHCl₃); ¹H NMR (500 MHz, CDCl₃) d 8.10 (br s, 1H, imidazole),

7.44 (br s, 1H, imidazole), 7.36–7.38 (m, 2H, ArH), 7.31–7.32 (m,

3H, ArH), 7.08–7.10 (m, 2H, ArH), 6.99 (br s, 1H, imidazole),

6.66–6.67 (m, 2H, ArH), 6.11 (dd, 1H, J_2,3ꢂ J_3,49.3 Hz, H-3), 5.46

(s, 1H, PhCHO₂), 4.74 (d, 1H, J_gem11.8 Hz, PhCH₂O), 4.59 (d, 1H,

J_1,27.5 Hz, H-1), 4.54 (d, 1H, J_gem11.8 Hz, PhCH₂O), 4.41 (dd, 1H,

J_5,65.0, J_gem10.5 Hz, H-6a), 3.80 (dd, 1H, J_5,6ꢂ J_gem10.3 Hz, H-6b),

3.76 (dd, 1H, J_3,4ꢂ J_4,59.5 Hz, H-4), 3.74 (s, 3H, CH₃O), 3.64 (s,

3H, CH₃O), 3.56–3.61 (m, 2H, H-2, H-5); ¹³C NMR (125 MHz, CDCl₃)

d 183.7 (C@S), 159.5 (Ar), 136.7 (Ar), 136.5 (Ar), 130.5 (Ar), 130.0

(Ar), 129.2 (Ar), 129.1 (Ar), 128.2 (Ar), 126.1 (Ar), 118.2 (Ar),

113.6 (Ar), 105.3 (C-1), 101.4 (PhCHO₂), 81.0 (C-3), 78.7 (C-4),

78.0 (C-2/C-5), 73.6 (PhCH₂O), 68.7 (C-6), 65.7 (C-2/C-5), 57.7

(CH₃O), 55.1 (CH₃O); HRESIMS: Calcd for C₂₆H₂₈N₂O₇SNa

535.1509. Found 535.1511. Anal. Calcd for C₂₆H₂₈N₂O₇S: C, 60.92;

H, 5.51; N, 5.47; S, 6.26. Found: C, 61.03; H, 5.58; N, 5.46; S, 5.96.

3.7. Methyl b-D-mannopyranosyl-(1?2)-6-O-methyl-b-D-

mannopyranoside (7)

Compound 52 (50.0 mg, 0.061 mmol) was dissolved in 1:1

CH₂Cl₂–MeOH (10 mL) and stirred with 10% Pd/C (50 mg) under

an H₂atmosphere, then processed as described for 2. Filtration,

then lyophilization, gave 7 (15.6 mg, 69%) as a clear glass: R_f0.33

(6:3.5:0.5, CH₂Cl₂–CH₃OH–H₂O); [

a

]

ꢀ73 (c 0.25, H₂O); ¹H NMR

D

(500 MHz, D₂O) d 4.82 (d, 1H, J_{1 ,2}0.8 Hz, H-1⁰), 4.63 (s, 1H, H-1),

0

4.25 (d, 1H, J_2,32.9 Hz, H-2), 4.11 (dd, 1H, J_{1 ,2}0.7, J_{2 ,3}3.3 Hz, H-

2⁰), 3.92 (dd, 1H, J_{5 ,6}2.3, J_gem12.3 Hz, H-6a⁰), 3.80 (dd, 1H, J_5,6

0

2.1, J_gem11.2 Hz, H-6a), 3.73 (dd, 1H, J_{5 ,6}6.7, J_gem12.3 Hz, H-6b⁰),

3.67 (dd, 1H, J_5,66.3, J_gem11.3 Hz, H-6b), 3.62–3.64 (m, 2H, H-3⁰,

0

H-3), 3.59 (dd, 1H, J_3,4ꢂ J_4,59.3Hz, H-4), 3.56 (dd, 1H, J_{3 ,4}ꢂ J_{4 ,5}

3.10. Methyl 4,6-O-benzylidene-3-deoxy-2-O-(4-

methoxybenzyl)-b-D-ribo-hexopyranoside (11)

9.7 Hz, H-4⁰), 3.53 (s, 3H, CH₃O–C1), 3.49 (ddd, 1H, J_4,59.2, J_5,6

0

2.2, 6.3 Hz, H-5), 3.42 (s, 3H, CH₃O–C6), 3.36 (ddd, 1H, J_{4 ,5}9.7,

J_{5 ,6}2.2, 6.6 Hz, H-5⁰); ¹³C NMR (125 MHz, D₂O) d 102.3 (C-1,

To a solution of compound 10 (880 mg, 1.72 mmol) in dry tolu-

ene (20 mL) were added tributyltin hydride (1.50 mL, 5.16 mmol)

and AIBN (71 mg, 0.43 mmol). The reaction was stirred at reﬂux

under argon for 16 h, cooled then concentrated under reduced

pressure. The residue was redissolved in a small volume of CH₂Cl₂

and passed through a plug of silica gel containing 10% (w/w) KF.

The ﬁltrate was concentrated, and the residue was subjected to

chromatography on silica gel (4:1 hexane–EtOAc) to give the deox-

ygenated product 11 (515 mg, 78%) as a white solid: R_f0.55 (1:1

0

¹J_C1,H1160.1 Hz, b), 101.3 (C-1⁰, J_C1,H1162.4 Hz, b), 78.5 (C-2),

1

77.2 (C-5⁰), 75.8 (C-5), 73.6, 73.1 (C-3⁰, C-3), 72.1 (C-6), 71.2 (C-

2⁰), 68.1 (C-4), 67.7 (C-4⁰), 62.0 (C-6⁰), 59.4 (CH₃OC-6), 58.1

(CH₃OC-1); HRESIMS: Calcd for C₁₄H₂₆O₁₁Na 393.1367. Found

393.1365.

3.8. Methyl 4,6-O-benzylidene-2-O-(4-methoxybenzyl)-b-D-

glucopyranoside (9)

hexanes–EtOAc); [

a]

ꢀ40 (c 0.76, CHCl₃); ¹H NMR (500 MHz,

D

Methyl 4,6-O-benzylidene-b-

D

-glucopyranoside (8)¹⁵(3.0 g,

CDCl₃) d 7.47–7.48 (m, 2H, ArH), 7.34–7.47 (m, 3H, ArH), 7.26–

7.29 (m, 2H, ArH), 6.87–6.89 (m, 2H, ArH), 5.49 (s, 1H, PhCHO₂),

4.72 (d, 1H, J_gem11.5 Hz, PhCH₂O), 4.59 (d, 1H, J_gem11.5 Hz,

PhCH₂O), 4.39 (d, 1H, J_1,27.5 Hz, H-1), 4.32 (dd, 1H, J_5,65.0, J_gem

10.6 Hz, H-6a), 3.81 (s, 3H, CH₃O), 3.74 (dd, 1H, J_5,6ꢂ J_gem

10.3 Hz, H-6b), 3.59 (s, 3H, CH₃O), 3.51 (ddd, 1H, J_3eq,44.4, J_3ax,4

11.9, J_4,59.1 Hz, H-4), 3.37–3.43 (m, 2H, H-2, H-5), 2.39 (ddd, 1H,

J_2,3ꢂ J_3,44.7, J_gem12.1 Hz, H-3eq), 1.74 (ddd, 1H, J_2,3ꢂ J_3,4ꢂ J_gem

11.8 Hz, H-3ax); ¹³C NMR (125 MHz, CDCl₃) d 159.3 (Ar), 137.3

10.63 mmol), tetrabutylammonium hydrogensulfate (902 mg,

2.66 mmol) and 4-methoxybenzyl chloride (1.8 mL, 13.28 mmol)

were dissolved in CH₂Cl₂(80 mL). Aq NaOH (20 mL of a 5% solu-

tion) was added, and the mixture was stirred under reﬂux over-

night. The reaction mixture was cooled, and the organic layer

was separated, washed with water, dried (Na₂SO₄) and then con-

centrated under reduced pressure. Puriﬁcation by chromatography

on silica gel (4:1 hexanes–EtOAc) gave the 2-O-(4-methoxybenzyl)

C. M. Nycholat, D. R. Bundle / Carbohydrate Research 344 (2009) 555–569

561

(Ar), 130.4 (Ar), 129.4 (Ar), 129.1 (Ar), 128.3 (Ar), 126.1 (Ar), 113.8

(Ar), 106.4 (C-1), 101.6 (PhCHO₂), 76.1 (C-4), 75.1 (C-2), 72.3

(PhCH₂O), 70.0 (C-5), 69.2 (C-6), 57.2 (CH₃O), 55.3 (CH₃O), 34.7

(C-3); HRESIMS: Calcd for C₂₂H₂₆O₆Na 409.1622. Found

409.1618. Anal. Calcd for C₂₂H₂₆O₆: C, 68.38; H, 6.78. Found: C,

68.22; H, 6.77.

overnight in toluene (40 mL) with azeotropic removal of water

using a Dean–Stark trap. The reaction mixture was cooled to room

temperature, then concentrated under reduced pressure. The solid

residue was redissolved in DMF (15 mL), methyl iodide (3.3 mL,

53.4 mmol) added, and the reaction was stirred at 40 °C. After

15 h, the reaction was cooled, then concentrated under reduced

pressure. Puriﬁcation by chromatography over silica gel (1:1 tolu-

ene–EtOAc) gave 14 (1.11 g, 71%) as a white solid: R_f0.22 (1:1 hex-

3.11. Methyl 4,6-O-benzylidene-3-deoxy-b-D-ribo-

hexopyranoside (12)

anes–EtOAc); [

a

]

D

ꢀ50 (c 1.0, CHCl₃); ¹H NMR (500 MHz, CDCl₃) d

7.48–7.50 (m, 2H, ArH), 7.34–7.40 (m, 3H, ArH), 5.56 (s, 1H,

PhCHO₂), 4.36 (dd, 1H, J_5,65.0, J_gem10.4 Hz, H-6eq), 4.35 (d, 1H,

J_1,27.5 Hz, H-1), 3.80 (dd, 1H, J_5,6ꢂ J_gem10.3 Hz, H-6ax), 3.68 (s,

3H, CH₃O), 3.63 (dd, 1H, J_3,4ꢂ J_4,59.2 Hz, H-4), 3.59 (s, 3H, CH₃O),

3.42–3.49 (m, 3H, H-2, H-3, H-5), 2.53 (d, 1H, J_2,OH1.9 Hz, OH);

¹³C NMR (125 MHz, CDCl₃) d 137.2 (Ar), 129.0 (Ar), 128.3 (Ar),

126.0 (Ar), 104.2 (C-1), 101.3 (PhCHO₂), 82.2 (C-3), 81.6 (C-4),

74.1 (C-2), 68.7 (C-6), 66.4 (C-5), 60.9 (CH₃O), 57.4 (CH₃O); HRE-

SIMS: Calcd for C₁₅H₂₀O₆Na 319.1152. Found 319.1152. Anal. Calcd

for C₁₅H₂₀O₆: C, 60.80; H, 6.80. Found: C, 60.92; H, 6.75.

To a solution of 11 (499 mg, 1.29 mmol mmol) in CH₂Cl₂

(22 mL) and H₂O (3 mL) at 0 °C (ice-water bath) was added 2,3-di-

chloro-5,6-dicyano-1,4-benzoquinone (879 mg, 3.87 mmol). The

reaction was allowed to slowly warm to room temperature, and

after 5 h it was diluted with CH₂Cl₂. The organic phase was washed

with 10% aq NaHCO₃, distilled H₂O and brine, then dried (Na₂SO₄).

Concentration under reduced pressure, followed by puriﬁcation by

column chromatography over silica gel (3:2 hexanes–EtOAc), gave

12 (294 mg, 86%) as a white solid: R_f0.27 (1:1 hexanes–EtOAc);

[

a]

D

ꢀ52 (c 0.47, CHCl₃); ¹H NMR (500 MHz, CDCl₃) d 7.48–7.50

(m, 2H, ArH), 7.34–7.40 (m, 3H, ArH), 5.54 (s, 1H, PhCHO₂), 4.34

(dd, 1H, J_5,64.9, J_gem10.5 Hz, H-6a), 4.26 (d, 1H, J_1,27.5 Hz, H-1),

3.78 (dd, 1H, J_5,6ꢂ J_gem10.4 Hz, H-6b), 3.57–3.63 (m, 2H, H-2, H-

4), 3.58 (s, 3H, CH₃O), 3.46 (ddd, 1H, J_4,59.1, J_5,64.9, 10.1 Hz, H-

5), 2.47 (ddd, 1H, J_2,3ꢂ J_3,44.7, J_gem11.9 Hz, H-3eq), 2.32 (br s,

1H, OH), 1.76 (ddd, 1H, J_2,3ꢂ J_gemꢂ J_3,411.7Hz, H-3ax); ¹³C NMR

(125 MHz, CDCl₃) d 137.3 (Ar), 129.1 (Ar), 128.3 (Ar), 126.2 (Ar),

106.4 (C-1), 101.8 (PhCHO₂), 76.2 (C-4), 70.6 (C-5), 69.2, 69.1

(C-2, C-6), 57.3 (CH₃O), 35.0 (C-3); HRESIMS: Calcd for C₁₄H₁₈O₅Na

289.1047. Found 289.1046. Anal. Calcd for C₁₄H₁₈O₅: C, 63.15; H,

6.81. Found: C, 63.11; H, 6.80.

3.14. Methyl 4,6-O-benzylidene-3-O-methyl-b-D-

mannopyranoside (15)

Compound 14 (446 mg, 1.51 mmol) was dissolved in a mixture

of Me₂SO (6 mL) and Ac₂O (3 mL). After stirring overnight, the mix-

ture was concentrated under reduced pressure. The remaining

solid was redissolved in 1:1 CH₂Cl₂–MeOH (10 mL) and cooled to

0 °C (ice-water bath). NaBH₄(286 mg, 7.53 mmol) was added,

and the reaction was stirred until starting material was consumed

according to TLC. The reaction was diluted with CH₂Cl₂, then

washed successively with 2% aq citric acid, brine and dried

(Na₂SO₄), then concentrated under reduced pressure. Chromatog-

raphy over silica gel (7:3 hexanes–EtOAc) gave 15 (356 mg, 80%)

3.12. Methyl 4,6-O-benzylidene-3-deoxy-b-D-arabino-

hexopyranoside (13)

as a white solid: R_f0.07 (1:1 hexanes–EtOAc); [

a

]

ꢀ74 (c 1.0,

D

CHCl₃); ¹H NMR (600 MHz, CDCl₃) d 7.48–7.50 (m, 2H, ArH),

7.33–7.38 (m, 3H, ArH), 5.59 (s, 1H, PhCHO₂), 4.48 (d, 1H, J_1,2

1.0 Hz, H-1), 4.35 (dd, 1H, J_5,65.0, J_gem10.3 Hz, H-6eq), 4.21 (d,

1H, J_2,33.2 Hz, H-2), 4.06 (dd, 1H, J_3,4ꢂ J_4,59.5 Hz, H-4), 3.89 (dd,

1H, J_5,6ꢂ J_gem10.3Hz, H-6ax), 3.59 (s, 3H, CH₃O), 3.58 (s, 3H,

CH₃O), 3.47 (dd, 1H, J_2,33.2, J_3,49.6 Hz, H-3), 3.39 (ddd, 1H, J_4,5

9.8, J_5,64.9, 9.8 Hz, H-5), 2.49 (br s, 1H, OH); ¹³C NMR (125 MHz,

CDCl₃) d 137.4 (Ar), 129.0 (Ar), 128.2 (Ar), 126.1 (Ar), 101.7,

101.4 (C-1, PhCHO₂), 79.3 (C-3), 78.4 (C-4), 69.0 (C-2), 68.6 (C-6),

66.8 (C-5), 58.6 (CH₃O), 57.3 (CH₃O); HRESIMS: Calcd for

C₁₅H₂₀O₆Na 319.1152. Found 319.1154. Anal. Calcd for C₁₅H₂₀O₆:

C, 60.80; H, 6.80. Found: C, 61.20; H, 6.73.

Compound 12 (294 mg, 1.10 mmol) was dissolved in a mixture

of freshly distilled Me₂SO (6 mL) and Ac₂O (3 mL). After stirring for

8 h at room temperature, the reaction was concentrated under

reduced pressure. The residue was redissolved in dry THF

(10 mL) and cooled to ꢀ78 °C °C. A 1.0 M solution of L-Selectride^Ò

in THF (4.4 mL, 4.41 mmol) was added dropwise, and stirring was

continued for 2 h at ꢀ78 °C. The reaction was quenched with

MeOH then diluted with CH₂Cl₂. The mixture was washed with

10% aq H₂O₂, 1 M aq NaOH, distilled H₂O, then brine. The organic

phase was dried (Na₂SO₄), then concentrated under reduced pres-

sure. Puriﬁcation by chromatography over silica gel (3:2 hexanes–

EtOAc) gave 13 (243 mg, 83%) as a white solid: R_f0.28 (1:1 hex-

anes–EtOAc); [

a

]

D

ꢀ64 (c 1.0, CHCl₃); ¹H NMR (500 MHz, CDCl₃)

3.15. Methyl 2-O-acetyl-3,4,6-tri-O-benzyl-b-

D

-glucopyranosyl-

d 7.47–7.50 (m, 2H, ArH), 7.32–7.39 (m, 3H, ArH), 5.57 (s, 1H,

PhCHO₂), 4.50 (d, 1H, J_1,21.3 Hz, H-1), 4.31 (dd, 1H, J_5,65.0, J_gem

10.4 Hz, H-6eq), 3.98–4.03 (m, 2H, H-2, H-4), 3.84 (dd, 1H,

J_5,6ꢂ J_gem10.3, H-6ax), 3.58 (s, 3H, CH₃O), 3.45 (dd, 1H, J_4,59.3,

J_5,65.0, 10.1 Hz, H-5), 2.44 (dd, 1H, J_2,OHꢂ J_3ax,OH1.7 Hz, C2-OH),

2.39 (ddd, 1H, J 3.2, 4.5, J_gem13.4 Hz, H-3eq), 1.79 (dddd, 1H, J_2,3

3.0, J_3,411.8, J_gem13.5, J_3,OH1.9 Hz, H-3ax); ¹³C NMR (125 MHz,

CDCl₃) d 137.5 (Ar), 129.0 (Ar), 128.3 (Ar), 126.1 (Ar), 102.0,

101.8 (C-1, PhCHO₂), 73.5 (C-4), 70.6 (C-5), 69.0 (C-6), 67.9 (C-2),

56.8 (CH₃O), 33.9 (C-3); HRESIMS: Calcd for C₁₄H₁₈O₅Na

289.1046. Found 289.1043. Anal. Calcd for C₁₄H₁₈O₅: C, 63.15; H,

6.81. Found: C, 63.05; H, 6.88.

(1?2)-4,6-O-benzylidene-3-deoxy-b-^D-arabino-hexopyranoside

(17)

Monosaccharide acceptor 13 (120 mg, 0.45 mmol) was reacted

with 2-O-acetyl-3,4,6-tri-O-benzyl-b- -glucopyranosyl trichloro-

acetimidate (16) (344 mg, 0.54 mmol) in CH₂Cl₂(5 mL) using

TMSOTf (5 L, 0.03 mmol) under argon at 0 °C. The reaction was

D

l

neutralized with Et₃N, ﬁltered through Celite then concentrated

under reduced pressure. The product was puriﬁed by chromatogra-

phy over silica gel (7:3 hexanes–EtOAc) to give 17 (196 mg, 59%) as

a white solid: R_f0.52 (1:1 hexanes–EtOAc); [

a

]

ꢀ24 (c 0.24,

D

CHCl₃); ¹H NMR (500 MHz, CDCl₃) d 7.46–7.48 (m, 2H, ArH),

7.25–7.38 (m, 16H, ArH), 7.18–7.20 (m, 2H, ArH), 5.57 (s, 1H,

0

3.13. Methyl 4,6-O-benzylidene-3-O-methyl-b-D-

glucopyranoside (14)

PhCHO₂), 5.00 (dd, 1H, J_{1 ,2}8.0, J_{2 ,3}9.3 Hz, H-2⁰), 4.81 (d, 1H, J_gem

10.8 Hz, PhCH₂O), 4.78 (d, 1H, J_gem11.5 Hz, PhCH₂O), 4.73 (d, 1H,

J_gem11.2 Hz, PhCH₂O), 4.73 (d, 1H, J_{1 ,2}8.0 Hz, H-1⁰), 4.62 (d, 1H,

J_gem12.4 Hz, PhCH₂O), 4.57 (d, 1H, J_gem10.9 Hz, PhCH₂O), 4.55 (d,

1H, J_gem12.3 Hz, PhCH₂O), 4.39 (d, 1H, J_1,20.8 Hz, H-1), 4.26 (dd,

0

Methyl 4,6-O-benzylidene-b-

5.31 mmol) and dibutyltin oxide (1.46 g, 5.88 mmol) were reﬂuxed

D

-glucopyranoside (8)¹⁵(1.5 g,

562

C. M. Nycholat, D. R. Bundle / Carbohydrate Research 344 (2009) 555–569

0

1H, J_5,64.9, J_gem10.3 Hz, H-6eq), 4.03 (ddd, 1H, J_1,20.9, J_2,33.1 Hz,

H-2), 3.93 (ddd, 1H, J_3,44.6, 12.6 Hz, J_4,59.5 Hz, H-4), 3.80 (dd,

1H, J_5,6ꢂ J_gem10.2 Hz, H-6ax), 3.63–3.74 (m, 4H, H-3⁰, H-4⁰, H-6a⁰,

3.87 (dd, 1H, J_5,6ꢂ J_gem10.3 Hz, H-6ax), 3.85 (dd, 1H, J_{3 ,4}ꢂ J_{4 ,5}

9.3 Hz, H-4⁰), 3.76 (dd, 1H, J_{5 ,6}2.0, J_gem10.8 Hz, H-6a⁰), 3.68 (dd,

0 0

1H, J_{5 ,6}5.7, J_gem10.8 Hz, H-6b⁰), 3.57 (dd, 1H, J_{2 ,3}3.0, J_{3 ,4}

0

H-6b⁰), 3.48 (ddd, 1H, J_{4 ,5}9.6, J_{5 ,6}2.6, 4.7Hz, H-5⁰), 3.47 (s, 3H,

CH₃O), 3.40 (ddd, 1H, J_4,59.4, J_5,64.9, 10.1 Hz, H-5), 2.39 (ddd,

1H, J_2,34.0, J_gem12.7, J_3,44.0 Hz, H-3eq), 2.00 (s, 3H, CH₃C(O)O),

1.76 (ddd, 1H, J_2,32.7, J_gem12,4, J_3,412.4Hz, H-3ax); ¹³C NMR

(125 MHz, CDCl₃) d 169.9 (C@O), 138.4 (Ar), 138.2 (Ar), 138.0

(Ar), 137.7 (Ar), 128.9 (Ar), 128.3(8) (Ar), 128.3(6) (Ar), 128.3

(Ar), 128.0 (Ar), 127.8 (Ar), 127.7(4) (Ar), 127.6(7) (Ar), 127.6(2)

(Ar), 127.5(7) (Ar), 126.1 (Ar), 103.2 (C-1), 101.8 (PhCHO₂), 101.5

(C-1⁰), 82.8 (C-3⁰), 77.9 (C-4⁰), 75.0(4), 75.0(0), 74.8 (C-5⁰,

PhCH₂O ꢃ 2), 73.7, 73.6 (C-2⁰, C-2, C-4), 73.4 (PhCH₂O), 71.1 (C-

5), 69.0, 68.9 (C-6⁰, C-6), 56.8 (CH₃O), 34.7 (C-3), 21.1 (CH₃C(O)O);

HRESIMS: Calcd for C₄₃H₄₈O₁₁Na 763.3089. Found 763.3084. Anal.

Calcd for C₄₃H₄₈O₁₁: C, 69.71; H, 6.53. Found: C, 69.68; H, 6.64.

9.1 Hz, H-3⁰), 3.52 (s, 3H, CH₃O), 3.42–3.48 (m, 2H, H-5⁰, H-5),

2.51 (ddd, 1H, J_2,3ꢂ J_3,44.0, J_gem13.1 Hz, H-3eq), 1.83 (ddd, 1H,

J_2,32.9, J_gem13.0, J_3,412.0 Hz, H-3ax); ¹³C NMR (125 MHz, CDCl₃)

0

d

138.2(8), 138.2(6), 137.9, 137.5, 129.0, 128.4, 128.3(4),

128.2(8), 128.1, 127.9, 127.8, 127.7(1), 127.6(9), 127.5, 126.1,

103.2, 101.8, 100.9, 81.4, 75.4, 75.1, 74.3, 74.1, 73.8, 73.5, 71.1(3),

71.0(9), 69.5, 68.9, 67.8, 57.3, 34.7; HRESIMS: Calcd for

C₄₁H₄₆O₁₀Na 721.2983. Found 721.2985.

3.18. Methyl 2-O-acetyl-3,4,6-tri-O-benzyl-b-

D

-glucopyranosyl-

D-mannopyranoside

(1?2)-4,6-O-benzylidene-3-O-methyl-b-

(20)

Monosaccharide acceptor 15 (205 mg, 0.69 mmol) was reacted

with 2-O-acetyl-3,4,6-tri-O-benzyl-b- -glucopyranosyl trichloro-

acetimidate (16) (484 mg, 0.76 mmol) in CH₂Cl₂(5 mL) using

TMSOTf (6 L, 0.03 mmol) under argon at 0 °C, then processed as

3.16. Methyl 3,4,6-tri-O-benzyl-b-

D

-glucopyranosyl-(1?2)-4,6-

D

O-benzylidene-3-deoxy-b- -arabino-hexopyranoside (18)

D

l

Disaccharide 17 (176 mg, 0.24 mmol) was dissolved in 1:1

CH₂Cl₂–MeOH (2 mL) and treated with 0.5 M NaOCH₃–CH₃OH

(2 mL). After 2 h, the reaction was neutralized with Amberlite IR-

120 (H⁺) resin and ﬁltered. Puriﬁcation of the product by chroma-

tography over silica gel (7:3 hexanes–EtOAc) gave 18 (166 mg,

described for 17. The product was puriﬁed by chromatography over

silica gel (7:3 hexanes–EtOAc) to give 20 (513 mg, 97%) as a white

solid: R_f0.49 (1:1 hexanes–EtOAc); [

NMR (600 MHz, CDCl₃) d 7.46–8.48 (m, 2H, ArH), 7.27–7.36 (m,

a

]

ꢀ40 (c 0.67, CHCl₃); ¹H

D

16H, ArH), 7.21–7.22 (m, 2H, ArH), 5.57 (s, 1H, PhCHO₂), 5.10 (dd,

1H, J_{1 ,2}8.0, J_{2 ,3}9.6 Hz, H-2⁰), 4.82 (d, 1H, J_gem11.0 Hz, PhCH₂O),

0

quant.) as a white solid: R_f0.33 (1:1 hexanes–EtOAc); [

a

]

ꢀ5 (c

D

0.82, CHCl₃); ¹H NMR (500 MHz, CDCl₃) d 7.47–7.50 (m, 2H, ArH),

7.23–7.42 (m, 16H, ArH), 7.18–7.20 (m, 2H, Ar), 5.59 (s, 1H,

PhCHO₂), 5.05 (d, 1H, J_gem11.2 Hz, PhCH₂O), 4.87 (d, 1H, J_gem

10.9 Hz, PhCH₂O), 4.80 (d, 1H, J_gem11.2 Hz, PhCH₂O), 4.60 (d, 1H,

J_gem12.2 Hz, PhCH₂O), 4.55 (d, 1H, J_gem12.4 Hz, PhCH₂O), 4.54 (d,

4.79 (d, 1H, J_gem11.5 Hz, PhCH₂O), 4.77 (d, 1H, J_{1 ,2}8.0 Hz, H-1⁰),

4.75 (d, 1H, J_gem11.5 Hz, PhCH₂O), 4.58 (d, 1H, J_gem12.1 Hz, PhCH₂O),

4.57 (d, 1H, J_gem11.0 Hz, PhCH₂O), 4.54 (d, 1H, J_gem12.0 Hz, PhCH₂O),

4.35 (s, 1H, H-1), 4.28 (dd, 1H, J_5,64.7, J_gem10.1 Hz, H-6eq), 4.26 (d,

1H, J_2,33.0 Hz, H-2), 3.99 (dd, 1H, J_3,4ꢂ J_4,59.6 Hz, H-4), 3.82 (dd,

0

1H, J_gem10.8 Hz, PhCH₂O), 4.50 (s, 1H, H-1), 4.41 (d, 1H, J_{1 ,2}

1H, J_5,6ꢂ J_gem10.2 Hz, H-6b), 3.75 (dd, 1H, J_{2 ,3}9.5, J_{3 ,4}8.5 Hz, H-

7.3 Hz, H-1⁰), 4.32 (dd, 1H, J_5,64.9, J_gem10.4 Hz, H-6eq), 4.01–4.06

(m, 2H, H-2, H-4), 3.87 (dd, 1H, J_5,6ꢂ J_gem10.4 Hz, H-6ax), 3.63–

3.74 (m, 4H, H-2⁰, H-3⁰, H-6a⁰, H-6b⁰), 3.56–3.60 (m, 4H, H-4⁰,

CH₃O), 3.44–3.52 (m, 2H, H-5⁰, H-5), 2.55 (ddd, 1H, J_2,3ꢂ J_3,43.8,

J_gem13.1 Hz, H-3eq), 1.84 (ddd, 1H, J_2,31.8, J_3,4ꢂ J_gem12.9 Hz, H-

3ax); ¹³C NMR (125 MHz, CDCl₃) d 138.9 (Ar), 138.2 (Ar), 138.1

(Ar), 137.5 (Ar), 129.0 (Ar), 128.3(8) (Ar), 128.3(5) (Ar), 128.3(2)

(Ar), 128.3(1) (Ar), 128.0(0) (Ar), 127.9(8) (Ar), 127.7 (Ar), 127.6

(Ar), 127.5 (Ar), 126.1 (Ar), 106.0 (C-1⁰), 102.5 (C-1), 101.9

(PhCHO₂), 84.8 (C-2⁰), 77.6 (C-2), 77 (C-4⁰), 75.6, 75.3 (C-5⁰, C-3),

75.1 (PhCH₂O), 74.9 (PhCH₂O), 73.7, 73.5 (C-4, PhCH₂O), 70.9 (C-

5), 69.0(2), 68.9(7) (C-6⁰, C-6), 57.2 (CH₃O), 35.0 (C-3); HRESIMS:

Calcd for C₄₁H₄₆O₁₀Na 721.2983. Found 721.2986. Anal. Calcd for

C₄₁H₄₆O₁₀: C, 70.47; H, 6.63. Found: C, 70.47; H, 6.68.

3⁰), 3.74 (dd, 1H, J_{5 ,6}1.8, J_gem10.9 Hz, H-6a⁰), 3.63 (dd, 1H, J_{5 ,6}6.2,

0

J_gem10.9 Hz, H-6b⁰), 3.57 (dd, 1H, J_{3 ,4}8.6, J_{4 ,5}9.8 Hz, H-4⁰), 3.53

0

(ddd, 1H, J_{4 ,5}9.8, J_{5 ,6}1.7, 6.0Hz, H-5⁰), 3.49 (s, 3H, CH₃O), 3.46 (s,

3H, CH₃O), 3.37 (dd, 1H, J_2,33.0, J_3,410.0 Hz H-3), 3.33 (ddd, 1H, J_4,5

9.9, J_5,65.0, 9.9 Hz, H-5), 1.99 (s, 3H, CH₃C(O)O); ¹³C NMR (125

MHz, CDCl₃) d 169.7 (C@O), 138.5 (Ar), 138.2 (Ar), 138.0 (Ar), 137.5

(Ar), 128.9 (Ar), 128.4 (Ar), 128.3(4) (Ar), 128.3(3) (Ar), 128.2 (Ar),

128.1 (Ar), 127.8 (Ar), 127.7(2) (Ar), 127.6(9) (Ar), 127.5(9) (Ar),

127.5(7) (Ar), 126.2 (Ar), 102.7 (C-1), 101.9 (PhCHO₂), 101.1 (C-1⁰),

83.0 (C-3⁰), 78.6 (C-3), 78.1 (C-4⁰), 77.7 (C-4), 75.1, 75.0, 74.8 (C-5⁰,

PhCH₂O ꢃ 2), 73.6(1), 73.5(8), 73.2 (C-2⁰, C-2, PhCH₂O), 69.7 (C-6⁰),

68.6 (C-6), 67.7 (C-5), 57.0 (CH₃O), 56.8 (CH₃O), 21.1 (CH₃C(O)O);

HRESIMS: Calcd for C₄₄H₅₀O₁₂Na 793.3195. Found 793.3195.

0

3.19. Methyl 3,4,6-tri-O-benzyl-b-D-glucopyranosyl-(1?2)-4,6-

3.17. Methyl 3,4,6-tri-O-benzyl-b-

D

-mannopyranosyl-(1?2)-

O-benzylidene-3-O-methyl-b- -mannopyranoside (21)

D

4,6-O-benzylidene-3-deoxy-b- -arabino-hexopyranoside (19)

D

Disaccharide 20 (513 mg, 0.67 mmol) was dissolved in 1:1

CH₂Cl₂–MeOH (4 mL) and treated with 0.5 M CH₃ONa–CH₃OH

(1 mL) then processed as described for 18. Puriﬁcation of the prod-

uct by chromatography over silica gel (7:3 hexanes–EtOAc) gave

21 (428 mg, 88%) as a white solid: R_f0.27 (1:1 hexanes–EtOAc);

Disaccharide 18 (140 mg, 0.200 mmol) was dissolved in freshly

distilled Me₂SO (5 mL) and Ac₂O (5 mL). The mixture was concen-

trated under reduced pressure, then the residue was redissolved in

dry THF and cooled to ꢀ78 °C under argon. The reaction mixture

was then treated with 1.0 M L-Selectride^Òin THF (1 mL, 1 mmol)

in dry THF (10 mL). Puriﬁcation by column chromatography over

silica gel (7:3 hexanes–EtOAc) gave 19 (90.8 mg, 65%) as a white

[a]

ꢀ38 (c 0.37, CHCl₃); ¹H NMR (500 MHz, CDCl₃) d 7.47–7.49

D

(m, 2H, ArH), 7.42–7.46 (m, 16H, ArH), 7.19–7.21 (m, 2H, ArH),

5.55 (s, 1H, PhCHO₂), 5.06 (d, 1H, J_gem11.2 Hz, PhCH₂O), 4.87 (d,

1H, J_gem11.0 Hz, PhCH₂O), 4.81 (d, 1H, J_gem11.2 Hz, PhCH₂O),

4.54 (s, 2H, PhCH₂O), 4.54 (d, 1H, J_gem10.9 Hz, PhCH₂O), 4.50 (d,

solid: R_f0.26 (1:1 hexanes–EtOAc); [

a]

D

ꢀ15 (c 0.60, CHCl₃); ¹H

NMR (500 MHz, CDCl₃) d 7.47–7.49 (m, 2H, ArH), 7.21–7.39 (m,

18H, ArH), 5.56 (s, 1H, PhCHO₂), 4.91 (d, 1H, J_gem10.9 Hz, PhCH₂O),

1H, J_{1 ,2}7.7 Hz, H-1⁰), 4.46 (d, 1H, J_1,20.6 Hz, H-1), 4.34 (dd, 1H,

J_5,64.9, J_gem10.4 Hz, H-6eq), 4.26 (d, 1H, J_2,33.2, H-2), 4.02 (dd,

1H, J_3,4ꢂ J_4,59.7 Hz, H-4), 3.87 (dd, 1H, J_5,6ꢂ J_gem10.3 Hz, H-6ax),

0

4.80 (d, 1H, J_gem11.9 Hz, PhCH₂O), 4.71 (d, 1H, J_{1 ,2}0.8 Hz, H-1⁰),

4.65 (d, 1H, J_gem12.0 Hz, PhCH₂O), 4.60 (d, 1H, J_gem12.2 Hz,

PhCH₂O), 4.56 (d, 1H, J_gem10.9Hz, PhCH₂O), 4.55 (d, 1H, J_gem

12.3 Hz, PhCH₂O), 4.46 (d, 1H, J_1,21.1 Hz, H-1), 4.31 (dd, 1H, J_5,6

0

3.76 (dd, 1H, J_{5 ,6}1.7, J_gem10.5 Hz, H-6a⁰), 3.74 (dd, 1H, J_{1 ,2}8.0,

0

J_{2 ,3}8.9Hz, H-2⁰), 3.67 (dd, 1H, J_{2 ,3}ꢂ J_{3 ,4}8.8 Hz, H-3⁰), 3.63 (dd,

0

4.9, J_gem10.4 Hz, H-6eq), 4.29 (dd, 1H, J_{1 ,2}0.9, J_{2 ,3}3.0 Hz, H-2⁰),

4.14 (ddd, 1H, H-2), 4.01 (ddd, 1H, J_3,43.3, 12.0, J_4,59.2 Hz, H-4),

1H, J_{5 ,6}6.4, J_gem10.5 Hz, H-6b⁰), 3.58 (s, 3H, CH₃O), 3.56 (ddd,

0

1H, J_{4 ,5}10.0, J_{5 ,6}1.7, 6.5 Hz, H-5⁰), 3.47 (dd, 1H, J_{3 ,4}8.5, J_{4 ,5}

0

C. M. Nycholat, D. R. Bundle / Carbohydrate Research 344 (2009) 555–569

563

9.7 Hz, H-4⁰), 3.48 (s, 3H, CH₃O), 3.42 (dd, 1H, J_2,33.2, J_3,410.0 Hz,

H-3), 3.38 (ddd, 1H, J_4,59.9, J_5,64.9, 9.9 Hz, H-5); ¹³C NMR

(125 MHz, CDCl₃) d 139.0 (Ar), 138.3 (Ar), 138.2 (Ar), 137.4 (Ar),

128.9 (Ar), 128.4 (Ar), 128.3(1) (Ar), 128.2(9) (Ar), 128.2 (Ar),

128.1 (Ar), 128.0 (Ar), 127.8 (Ar), 127.7 (Ar), 127.5(4) (Ar),

127.4(8) (Ar), 126.2 (Ar), 105.1 (C-1⁰), 102.1 (C-1), 101.8 (PhCHO₂),

85.2 (C-3⁰), 78.8 (C-3), 77.8 (C-4), 77.3 (C-4⁰), 76.4 (C-2), 75.4(9),

75.4(6) (C-2⁰, C-5⁰), 75.0 (PhCH₂O), 74.8 (PhCH₂O), 73.5 (PhCH₂O),

69.8 (C-6⁰), 68.6 (C-6), 67.5 (C-5), 57.5 (CH₃O), 57.4 (CH₃O); HRE-

SIMS: Calcd for C₄₂H₄₈O₁₁Na 751.3089. Found 751.3089. Anal.

Calcd for C₄₂H₄₈O₁₁: C, 69.21; H, 6.64. Found: C, 68.95; H, 6.82.

(Ar), 128.2 (Ar), 127.7 (Ar), 126.1 (Ar), 101.6 (PhCHO₂), 101.1 (C-

1), 78.4 (C-4), 75.6 (C-3), 71.6 (PhCH₂O), 69.3 (C-2), 68.7 (C-6),

67.4 (C-5), 57.5 (CH₃O); HRESIMS: Calcd for C₂₈H₂₈O₇Na

499.1727. Found 499.1729. Anal. Calcd for C₂₈H₂₈O₇: C, 70.57; H,

5.92. Found: C, 70.81; H, 5.73.

3.22. Methyl 2-O-benzoyl-3,6-di-O-benzyl-b-D-

mannopyranoside (25)

Compound 24 (3.43 g, 6.77 mmol) was dissolved in dry THF,

and the solution was cooled to 0 °C (ice-water bath) under argon.

Activated 4 Å molecular sieves and NaCNBH₃(2.13 g, 33.86 mmol)

were added. A satd solution of HCl in Et₂O was added dropwise

until the solution was acidic (pH paper, gas evolution). After 3 h,

the reaction was diluted with EtOAc and ﬁltered through Celite.

The organic phase was washed with satd aq NaHCO₃, dried

(Na₂SO₄) and concentrated under reduced pressure. The crude

product was puriﬁed by column chromatography (4:1 hexanes–

EtOAc) to give 25 (2.80 g, 81%) as a white solid: R_f0.40 (1:1 hex-

3.20. Methyl 3,4,6-tri-O-benzyl-b-

4,6-O-benzylidene-3-O-methyl-b-

D

-mannopyranosyl-(1?2)-

D

-mannopyranoside (22)

Disaccharide 21 (428 mg, 0.59 mmol) was dissolved in freshly dis-

tilled Me₂SO (10 mL) and Ac₂O (5 mL) then processed as described for

compound 19. The concentrated reaction mixture was then treated

with 1.0 M L-Selectride^Òin THF (2.4 mL, 2.35 mmol) in dry THF

(10 mL) at ꢀ78 °C under argon. Puriﬁcation by column chromatogra-

phy over silica gel (7:3 hexanes–EtOAc) gave 22 (308 mg, 72%) as a

anes–EtOAc); [

a

]

_Dꢀ113 (c 0.22, CHCl₃); ¹H NMR (500 MHz, CDCl₃)

d 8.07–8.09 (m, 2H, ArH), 7.54 (m, 1H, ArH), 7.26–7.41 (m, 12H,

ArH), 5.84 (dd, 1H, J_1,20.9, J_2,33.1 Hz, H-2) 4.85 (d, 1H, J_gem

11.4 Hz, PhCH₂O) 4.72 (d, 1H, J_gem12.1 Hz, PhCH₂O) 4.64 (d, 1H,

J_gem12.1 Hz, PhCH₂O) 4.55 (d, 1H, J_1,20.9 Hz, H-1) 4.50 (d, 1H, J_gem

11.4 Hz, PhCH₂O), 4.04 (ddd, 1H, J_4,OH2.0, J_3,4ꢂ J_4,59.4 Hz, H-4),

3.92 (ABX, 1H, J_5,63.2, J_gem10.7 Hz, H-6a), 3.88 (ABX, 1H, J_5,65.3,

J_gem10.7 Hz, H-6b), 3.54–3.58 (m, 2H, H-3, H-5), 3.53 (s, 3H,

CH₃O), 2.57 (d, 1H, J_4,OH2.1 Hz, OH); ¹³C NMR (125 MHz, CDCl₃) d

166.1 (C@O), 138.2 (Ar), 137.3 (Ar), 133.0 (Ar), 130.1 (Ar), 129.9

(Ar), 128.5 (Ar), 128.4 (Ar), 128.3 (Ar), 128.2 (Ar), 128.0 (Ar),

127.6 (Ar), 100.3 (C-1), 79.6 (C-3), 75.3 (C-5), 73.7 (PhCH₂O), 71.2

(PhCH₂O), 70.2 (C-6), 67.8(4), 67.8(0) (C-2, C-4), 57.2 (CH₃O); HRE-

SIMS: Calcd for C₂₈H₃₀O₇Na 501.1884. Found 501.1884.

white solid: R_f0.19 (1:1 hexanes–EtOAc); [a _D

]

ꢀ60 (c 0.47, CHCl₃);

¹H NMR (600 MHz, CDCl₃) d 7.49–7.50 (m, 2H, ArH), 7.24–7.40 (m,

18H, ArH), 5.58 (s, 1H, PhCHO₂), 4.94 (d, 1H,J_gem11.0Hz, PhCH₂O),

4.85 (d, 1H, J_{1 ,2}0.8 Hz, H-1⁰), 4.82 (d, 1H, J_gem12.1 Hz, PhCH₂O),

4.65 (d, 1H, J_gem12.0 Hz, PhCH₂O), 4.58 (d, 1H, J_gem12.0 Hz, PhCH₂O),

4.57 (d, 1H, J_gem11.0Hz, PhCH₂O), 4.52 (m, 1H, H-2), 4.51 (d, 1H, J_gem

0

12.0 Hz,PhCH₂O), 4.42(d, 1H, J_1,20.9 Hz,H-1),4.33(dd,1H, J_5,65.0,J_gem

0

10.4 Hz, H-6eq), 4.28 (dd, 1H, J_{1 ,2}0.7, J_{2 ,3}3.0 Hz, H-2 ), 4.01 (dd, 1H,

J_3,4ꢂ J_4,59.6 Hz, H-4), 3.89 (dd, 1H, J_{3 ,4}ꢂ J_{4 ,5}9.4 Hz, H-4⁰), 3.88 (dd,

0

1H, J_5,610.3 Hz, H-6ax), 3.77 (dd, 1H, J_{5 ,6}2.0, J_gem10.8 Hz, H-6a⁰), 3.71

0

(dd, 1H, J_{5 ,6}5.8 J_gem10.8 Hz, H-6b⁰), 3.55 (dd, 1H, J_{2 ,3}3.0, J_{3 ,4}9.1 Hz,

0

H-3⁰), 3.52 (s, 3H, CH₃O), 3.47 (ddd, 1H, J_{4 ,5}9.7, J_{5 ,6}1.9, 5.7Hz, H-5 ),

3.45 (s, 3H, CH₃O), 3.43 (dd, 1H, J_2,33.3, J_3,49.9 Hz, H-3), 3.38 (ddd, 1H,

J_4,59.9, J_5,64.9, 9.9 Hz, H-5); ¹³C NMR (125 MHz, CDCl₃) d 138.4 (Ar),

138.3 (Ar), 138.1 (Ar), 137.3 (Ar), 129.0 (Ar), 128.4 (Ar), 128.3 (Ar),

128.2 (Ar), 128.0 (Ar), 127.9 (Ar), 127.7 (Ar), 127.6(4) (Ar), 127.5(7)

(Ar), 126.2 (Ar), 102.9 (C-1), 101.8 (PhCHO₂), 98.1 (C-1⁰), 81.4 (C-3⁰),

78.8 (C-3), 77.7 (C-4), 75.3, 75.1, 74.3 (C-4⁰, C-5⁰, PhCH₂O), 73.4

(PhCH₂O), 70.8, 70.7 (C-2, PhCH₂O), 69.8 (C-6⁰), 68.6 (C-6), 67.8, 67.5

(C-2⁰, C-5), 57.5(CH₃O), 57.1(CH₃O); HRESIMS:CalcdforC₄₂H₄₈O₁₁Na

751.3089. Found 751.3087. Anal. Calcd for C₄₂H₄₈O₁₁: C, 69.21; H,

6.64. Found: C, 68.85; H, 6.70.

0

3.23. Methyl 2-O-benzoyl-3,6-di-O-benzyl-4-O-thiocarbonyl

imidazole-b-D-mannopyranoside (26)

To a solution of 25 (1.43 g, 2.98 mmol) in dry toluene (20 mL)

under argon was added 1,1⁰-thiocarbonyldiimidazole (1.60 g,

8.95 mmol). The reaction was stirred at 90 °C. After 20 h, the reac-

tion was cooled to room temperature, then concentrated under

reduced pressure to give a brown oily residue. Puriﬁcation of the

product by chromatography (1:1 hexanes–EtOAc) yielded 26

(1.05 g, 60%) as a white solid: R_f0.28 (1:1 hexanes–EtOAc); [a]

D

3.21. Methyl 2-O-benzoyl-3-O-benzyl-4,6-O-benzylidene-b-

mannopyranoside (24)

D

-

ꢀ166 (c 0.29, CHCl₃); ¹H NMR (500 MHz, CDCl₃) d 8.13–8.15 (m,

2H, ArH), 8.10 (m, 1H, ArH), 7.59 (m, 1H, ArH), 7.43–7.46 (m, 3H,

ArH), 7.12–7.28 (m, 10H, ArH), 7.02 (m, 1H, ArH), 6.24 (dd, 1H,

J_3,4ꢂ J_4,59.3 Hz, H-4), 5.90 (dd, 1H, J_1,20.9, J_2,33.2 Hz, H-2), 4.69

(d, 1H, J_gem12.8 Hz, PhCH₂O), 4.61 (d, 1H, J_1,21.0 Hz, H-1), 4.54

(AB, 1H, J_gem11.7 Hz, PhCH₂O), 4.52 (AB, 1H, J_gem11.7 Hz, PhCH₂O),

4.45 (d, 1H, J_gem12.8 Hz, PhCH₂O), 3.83 (dd, 1H, J_2,33.2, J_3,49.4 Hz,

H-3), 3.72–3.82 (m, 3H, H-5, H-6a, H-6b), 3.45 (s, 3H, CH₃O); ¹³C

NMR (125 MHz, CDCl₃) d 183.4 (C@S), 166.0 (C@O), 137.6 (Ar),

136.8 (Ar), 136.6 (Ar), 133.2 (Ar), 130.8 (Ar), 130.2 (Ar), 129.7

(Ar), 128.5 (Ar), 128.4 (Ar), 128.3 (Ar), 128.2 (Ar), 127.9 (Ar),

127.7 (Ar), 127.6 (Ar), 118.2 (Ar), 100.2 (C-1), 77.2 (C-4), 75.8 (C-

3), 73.9 (PhCH₂O), 73.6 (C-5), 70.6 (PhCH₂O), 69.7 (C-6), 67.8 (C-

2), 57.4 (CH₃O); HRESIMS: Calcd for C₃₂H₃₂N₂O₇SNa 611.1822.

Found 611.1820. Anal. Calcd for C₃₂H₃₂N₂O₇S: C, 65.29; H, 5.48;

N, 4.76; S, 5.45. Found: C, 65.55; H, 5.53; N, 4.76; S, 5.27.

Methyl

3-O-benzyl-4,6-O-benzylidene-b-D-glucopyranoside

(23)¹⁵(1.54 g, 4.14 mmol) was dissolved in pyridine (40 mL). Ben-

zoyl chloride (1.5 mL, 12.41 mmol) was added, and the reaction

mixture was stirred at room temperature overnight, then concen-

trated under reduced pressure. The residue was dissolved in EtOAc

then washed with 1 M aq HCl, satd aq NaHCO₃, distilled H₂O and

brine. The organic phase was dried (Na₂SO₄), then concentrated

under reduced pressure. Column chromatography (4:1 hexanes–

EtOAc) on silica gel gave 24 (1.97 g, quant.) as a white solid: R_f

0.51 (1:1 hexanes–EtOAc); [

a

]

D

ꢀ115 (c 0.26, CHCl₃); ¹H NMR

(500 MHz, CDCl₃) d 8.13–8.16 (m, 2H, ArH), 7.23–7.59 (m, 13H,

ArH), 5.88 (dd, 1H, J_1,21.1, J_2,33.4 Hz, H-2), 5.68 (s, 1H, PhCHO₂),

4.79 (d, 1H, J_gem12.6 Hz, PhCH₂O), 4.69 (d, 1H, PhCH₂O), 4.60 (d,

1H, J_1,21.2Hz, H-1), 4.41 (dd, 1H, J_5,6eq4.9, J_gem10.5 Hz, H-6eq),

4.14 (dd, 1H, J_3,4ꢂ J_4,59.6 Hz, H-4), 3.98 (dd, 1H, J_5,6ax9.7, J_gem

10.4 Hz, H-6ax) 3.84 (dd, 1H, J_2,33.4, J_3,49.8 Hz, H-3), 3.53 (s, 3H,

CH₃O), 3.47 (ddd, 1H, J_4,59.7, J_5,64.8, 9.7 Hz, H-5); ¹³C NMR

(125 MHz, CDCl₃) d 166.1 (C@O), 137.7 (Ar), 137.4 (Ar), 133.1

(Ar), 130.1 (Ar), 129.9 (Ar), 129.0 (Ar), 128.3(3) (Ar), 128.3(0)

3.24. Methyl 2-O-benzoyl-3,6-di-O-benzyl-4-deoxy-b-D-lyxo-

hexopyranoside (27)

To a solution of the Barton–McCombie substrate 26 (1.05 g,

1.78 mmol) in dry toluene (15 mL) was added tributyltin hydride

564

C. M. Nycholat, D. R. Bundle / Carbohydrate Research 344 (2009) 555–569

(2 mL), and the mixture was then (1.43 mL, 5.33 mmol) and AIBN

(73 mg, 0.25 mmol). The reaction was reﬂuxed under argon over-

night, then cooled to room temperature. The reaction mixture was

ﬁltered through a plug of silica gel containing 10% (w/w) KF. The ﬁl-

trate was concentrated, then subjected to chromatography (4:1 hex-

anes–EtOAc) to give 27 (562.2 mg, 68%) as a white solid: R_f0.55 (1:1

for

C₂₉H₃₂O₇Na 515.2040. Found 515.2042. Anal. Calcd for

C₂₉H₃₂O₇: C, 70.71; H, 6.55. Found: C, 70.58; H, 6.54.

3.27. Methyl 3,6-di-O-benzyl-4-O-methyl-b-D-

mannopyranoside (30)

hexanes–EtOAc); [

a]

D

ꢀ101 (c 0.59, CHCl₃); ¹H NMR (500 MHz,

To a solution of mannopyranoside 29 (793.3 mg, 1.61 mmol) in

CH₂Cl₂(10 mL) and MeOH (10 mL) was added 0.5 M CH₃ONa–

CH₃OH (6 mL), and the reaction was stirred overnight. The reaction

was neutralized with Amberlite IR-120 (H⁺) resin, the resin was ﬁl-

tered and the ﬁltrate was concentrated under reduced pressure.

Puriﬁcation of the product by chromatography (1:1 hexanes–

EtOAc) gave 30 (592.5 mg, 95%) as a white solid: R_f0.28 (1:1 hex-

CDCl₃) d 8.11–8.12 (m, 2H, ArH), 7.53–7.56 (m, 1H, ArH), 7.25–

7.43 (m, 12H, ArH), 5.78 (dd, 1H, J_1,20.8, J_2,32.8 Hz, H-2), 4.74 (d,

1H, J_gem12.0Hz, PhCH₂O), 4.65 (s, 2H, PhCH₂O), 4.52 (d, 1H, J_gem

12.0 Hz, PhCH₂O), 4.42 (d, 1H, J_1,21.1 Hz, H-1), 3.76 (dd, 1H, J_5,6

5.5, J_gem9.4Hz, H-6a), 3.68–3.74 (m, 2H, H-3, H-5), 3.65 (dd, 1H,

J_5,64.2, J_gem9.4 Hz, H-6b) 3.51 (s, 3H, CH₃O), 1.91–1.94 (m, 2H, H-

4a, H-4b); ¹³C NMR (125 MHz, CDCl₃) d 166.2 (C@O), 138.3 (Ar),

137.8 (Ar), 132.9 (Ar), 130.2 (Ar), 130.1 (Ar), 128.4 (Ar), 128.2 (Ar),

127.7(1) (Ar), 127.6(8) (Ar), 100.7 (C-1), 74.0 (C-3), 73.6 (PhCH₂O),

72.7 (C-6), 72.0 (C-5), 70.0 (PhCH₂O), 67.2 (C-2), 57.1 (CH₃O), 30.0

(C-4); HRESIMS: Calcd for C₂₈H₃₀O₆Na 485.1935. Found 485.1936.

anes–EtOAc); [

a]

_Dꢀ34 (c 0.44, CHCl₃); ¹H NMR (500 MHz, CDCl₃) d

7.26–7.41 (m, 10H, ArH), 4.76 (d, 1H, J_gem11.9 Hz, PhCH₂O), 4.69 (d,

1H, J_gem11.8 Hz, PhCH₂O), 4.67 (d, 1H, J_gem12.0 Hz, PhCH₂O), 4.60

(d, 1H, J_gem12.1 Hz, PhCH₂O), 4.31 (d, 1H, H-1), 4.06 (m, 1H, H-

2), 3.80 (dd, 1H, J_5,62.2, J_gem10.8Hz, H-6a), 3.75 (dd, 1H, J_5,65.3, J_gem

10.9 Hz, H-6b), 3.57 (dd, 1H, J_3,4ꢂ J_4,59.3 Hz, H-4), 3.55 (s, 3H,

CH₃O), 3.53 (s, 3H, CH₃O), 3.46 (dd, 1H, J_2,33.1, J_3,49.0 Hz, H-3),

3.36 (ddd, 1H, J_4,59.6, J_5,62.1, 5.3Hz, H-5), 2.39 (d, 1H, J_2,OH

2.4 Hz, OH); ¹³C NMR (125 MHz, CDCl₃) d 138.4 (Ar), 138.0 (Ar),

128.5 (Ar), 128.3 (Ar), 127.8(2) (Ar), 127.8(0) (Ar), 127.7 (Ar),

127.5 (Ar), 100.7 (C-1), 81.3 (C-3), 76.2 (C-4), 75.4 (C-5), 73.6

(PhCH₂O), 71.5 (PhCH₂O), 69.4 (C-6), 68.3 (C-2), 60.8 (CH₃O), 56.9

(CH₃O); HRESIMS: Calcd for C₂₂H₂₈O₆Na 411.1778. Found

411.1778.

3.25. Methyl 3,6-di-O-benzyl-4-deoxy-b-D-lyxo-hexopyranoside

(28)

Compound 27 (534.3 mg, 1.16 mmol) was dissolved in MeOH

(10 mL). A solution of 0.5 M CH₃ONa–CH₃OH (6 mL) was added,

then the reaction was stirred at room temperature until TLC (1:1

hexanes–EtOAc) indicated the consumption of starting material.

The reaction was neutralized with Amberlite IR-120 (H⁺) resin.

The resin was ﬁltered and the ﬁltrate was concentrated under

reduced pressure. Puriﬁcation by chromatography (1:1 hexanes–

EtOAc) gave 28 (369.5 mg, 89%) as a white solid: R_f0.30 (1:1 hex-

3.28. Methyl 2-O-acetyl-3,4,6-tri-O-benzyl-b-

(1?2)-3,6-di-O-benzyl-4-deoxy-b- -lyxo-hexopyranoside (31)

D-glucopyranosyl-

D

anes–EtOAc); [

a]

_Dꢀ45 (c 1.15, CHCl₃); ¹H NMR (500 MHz, CDCl₃) d

7.28–7.36 (m, 10H, ArH), 4.56–4.66 (m, 4H, PhCH₂O ꢃ 4), 4.25 (d,

1H, J_1,21.0 Hz, H-1), 4.04 (br s, 1H, H-2), 3.67 (m, 1H, H-6a),

3.51–3.60 (m, 3H, H-3, H-5, H-6b), 3.56 (s, 3H, CH₃O), 2.28 (d,

1H, J_2,OH2.4Hz, OH), 1.84 (m, 1H, H-4a), 1.76 (m, 1H, H-4b); ¹³C

NMR (125 MHz, CDCl₃) d 138.2 (Ar), 137.9 (Ar), 128.5 (Ar), 128.4

(Ar), 127.8 (Ar), 127.7(2) (Ar), 127.6(9) (Ar), 127.6(7) (Ar), 101.3

(C-1), 75.0 (C-3), 73.6 (PhCH₂O), 72.7 (C-6), 71.7 (C-5), 69.9

(PhCH₂O), 67.3 (C-2), 56.9 (CH₃O), 28.3 (C-4); HRESIMS: Calcd for

C₂₁H₂₆O₅Na 381.1672. Found 381.1671.

Monosaccharide acceptor 28 (347 mg, 0.97 mmol) was reacted

with 2-O-acetyl-3,4,6-tri-O-benzyl-b- -glucopyranosyl trichloro-

acetimidate (16) (758 mg, 1.19 mmol) in CH₂Cl₂(5 mL) using

TMSOTf (5 L, 0.03 mmol) under argon at 0 °C (ice-water bath), then

processed as described for 17. The product was puriﬁed by chroma-

tography over silica gel (4:1 hexanes–EtOAc) to give 31 (669 mg,

D

l

83%) as a clear syrup: R_f0.59 (1:1 hexanes–EtOAc); [

a]

ꢀ55 (c

D

0.43, CHCl₃); ¹H NMR (500 MHz, CDCl₃) d 7.18–7.34 (m, 25H, ArH),

5.09 (dd, 1H, J_{1 ,2}8.0, J_{2 ,3}9.5 Hz, H-2⁰), 4.84 (d, 1H, J_{1 ,2}8.0 Hz, H-

1⁰) 4.81 (d, 1H, J_gem10.9 Hz, PhCH₂O), 4.80 (d, 1H, J_gem12.2Hz,

PhCH₂O), 4.78 (d, 1H, J_gem11.5 Hz, PhCH₂O), 4.74 (d, 1H, J_gem

11.4 Hz, PhCH₂O), 4.54–4.59 (m, 2H, PhCH₂O), 4.54 (d, 1H, J_gem

11.0 Hz, PhCH₂O), 4.47 (d, 1H, J_gem12.2Hz, PhCH₂O), 4.42–4.47 (m,

2H, PhCH₂O), 4.17 (d, 1H, J_2,32.5 Hz, H-2), 4.11 (s, 1H, H-1), 3.72–

3.77 (m, 2H, H-3⁰, H-6a⁰), 3.54–3.63 (m, 5H, H-4⁰, H-5⁰, H-6b⁰H-5,

H-6a), 3.48 (dd, 1H, J_5,64.0, J_gem9.7 Hz, H-6b), 3.46 (s, 3H, CH₃O),

3.40 (ddd, 1H, J_2,32.7, J_3,4eq4.7, J_3,4ax11.7Hz, H-3), 1.96 (s, 3H,

CH₃C(O)O), 1.75 (ddd, 1H, J_3,4ꢂ J_gemꢂ J_4,512.0 Hz, H-4ax), 1.65

(ddd, 1H, J_3,44.5, J_gem12.6, J_4,52.2 Hz, H-4eq); ¹³C NMR (125 MHz,

CDCl₃) d 169.7 (C@O), 138.5 (Ar), 138.4 (Ar), 138.3 (Ar), 138.2 (Ar),

138.0 (Ar), 128.4 (Ar), 128.3(2) (Ar), 128.2(9) (Ar), 128.2(6) (Ar),

128.1 (Ar), 127.9 (Ar), 127.8 (Ar), 127.7(2) (Ar), 127.6(7) (Ar),

127.6(1) (Ar), 127.5(8) (Ar), 127.5(5) (Ar), 127.4(9) (Ar), 127.4 (Ar),

102.4 (C-1), 100.9 (C-1⁰), 83.1 (C-3⁰), 78.2 (C-4⁰/C-5⁰/C-5), 75.0,

74.9, 74.7 (C-4⁰/C-5⁰/C-5, PhCH₂O ꢃ 2), 73.9 (PhCH₂O), 73.7 (C-3),

73.5, 73.4, 73.2 (C-2⁰, C-6, PhCH₂O), 72.0 (C-4⁰/C-5⁰/C-5), 71.4 (C-2),

69.9 (C-6⁰), 68.7 (PhCH₂O), 56.5 (CH₃O), 29.2 (C-4), 21.1 (CH₃C(O)O);

HRESIMS: Calcd for C₅₀H₅₆O₁₁Na 855.3715. Found 855.3710. Anal.

Calcd for C₅₀H₅₆O₁₁: C, 72.10; H, 6.78. Found: C, 72.10; H, 6.79.

0

3.26. Methyl 2-O-benzoyl-3,6-di-O-benzyl-4-O-methyl-b-D-

mannopyranoside (29)

Compound 25 (643.3 mg, 1.34 mmol) was dissolved in dry DMF

(10 mL) under argon. Methyl iodide (167 L, 2.69 mmol) was

l

added, and the reaction was cooled to 0 °C (ice-water bath). NaH

(107.5 mg, 2.69 mmol; 60% in oil) was added in one portion, and

the reaction was stirred at 0 °C for 3 h. The reaction was quenched

with HOAc, then concentrated under reduced pressure. Puriﬁcation

of the product by chromatography (4:1 hexanes–EtOAc) yielded 29

(643.8 mg, 97%) as a white solid: R_f0.54 (1:1 hexanes–EtOAc); [a]

D

ꢀ96 (c 0.22, CHCl₃); ¹H NMR (500 MHz, CDCl₃) d 8.09–8.11 (m, 2H,

ArH), 7.53 (m, 1H, ArH), 7.42–7.44 (m, 2H, ArH), 7.26–7.38 (m, 10H,

ArH), 5.81 (dd, 1H, J_1,20.8, J_2,33.0 Hz, H-2), 4.83 (d, 1H, J_gem11.6 Hz,

PhCH₂O), 4.81 (d, 1H, J_gem12.1 Hz, PhCH₂O), 4.65 (d, 1H, J_gem

12.0Hz, PhCH₂O), 4.58 (d, 1H, J_gem11.6 Hz, PhCH₂O), 4.49 (d, 1H,

J_1,20.9 Hz, H-1), 3.90 (dd, 1H, J_5,64.3, J_gem11.0Hz, H-6a), 3.87 (dd,

1H, J_5,62.1, J_gem11.0 Hz, H-6b), 3.71 (dd, 1H, J_3,4ꢂ J_4,59.3 Hz, H-

4), 3.66 (dd, 1H, J_2,33.0, J_3,49.2Hz, H-3), 3.55 (s, 3H, CH₃O), 3.52

(s, 3H, CH₃O), 3.46 (ddd, 1H, J_4,59.3, J_5,62.1, 4.3Hz, H-5); ¹³C

NMR (125 MHz, CDCl₃) d 166.0 (C@O), 138.6 (Ar), 137.8 (Ar),

132.9 (Ar), 130.1 (Ar), 128.3(4) (Ar), 128.3(3) (Ar), 128.2(6) (Ar),

128.0 (Ar), 127.7 (Ar), 127.5(0) (Ar), 127.4(6) (Ar), 100.2 (C-1),

80.1 (C-3), 76.2 (C-4), 75.8 (C-5), 73.5 (PhCH₂O), 71.2 (PhCH₂O),

69.3 (C-6), 68.4 (C-2), 61.0 (CH₃O), 57.2 (CH₃O); HRESIMS: Calcd

3.29. Methyl 3,4,6-tri-O-benzyl-b-

di-O-benzyl-4-deoxy-b- -lyxo-hexopyranoside (32)

D-glucopyranosyl-(1?2)-3,6-

D

Disaccharide 31 (448 mg, 0.54 mmol) was dissolved in 1:1

CH₂Cl₂–MeOH (10 mL) and treated with 0.5 M CH₃ONa–CH₃OH

C. M. Nycholat, D. R. Bundle / Carbohydrate Research 344 (2009) 555–569

565

(2 mL), then processed as described for 18. Puriﬁcation of the prod-

uct by chromatography over silica gel (7:3 hexanes–EtOAc) gave

32 (334 mg, 78%) as a colourless syrup: R_f0.42 (1:1 hexanes–

described for 17. The product was puriﬁed by chromatography

over silica gel (4:1 hexanes–EtOAc) to give 34 (511 mg, 97%) as a

colourless syrup: R_f0.54 (1:1 hexanes–EtOAc); [

a

]

D

ꢀ53 (c 0.65,

EtOAc); [

a]

ꢀ60 (c 0.88, CHCl₃); ¹H NMR (500 MHz, CDCl₃) d

CHCl₃); ¹H NMR (500 MHz, CDCl₃) d 7.17–7.39 (m, 25H, ArH),

D

5.09 (dd, 1H, J_{1 ,2}8.1, J_{2 ,3}9.6 Hz, H-2⁰), 4.86 (d, 1H, J_gem12.1Hz,

PhCH₂O), 4.80 (d, 1H, J_gem11.9 Hz, PhCH₂O), 4.79 (d, 1H, H-1⁰),

4.78 (d, 1H, J_gem11.5 Hz, PhCH₂O), 4.74 (d, 1H, J_gem11.5 Hz,

PhCH₂O), 4.61 (d, 1H, J_gem12.3Hz, PhCH₂O), 4.57 (d, 1H, J_gem

12.2 Hz, PhCH₂O), 4.54 (d, 1H, J_gem11.0 Hz, PhCH₂O), 4.52 (d, 1H,

J_gem12.1 Hz, PhCH₂O), 4.43–4.48 (m, 2H, PhCH₂O), 4.18–4.19 (m,

2H, H-1, H-2), 3.71–3.79 (m, 3H, H-3⁰, H-6a⁰, H-6a), 3.56–3.66 (m,

4H, H-4⁰, H-5⁰, H-6b⁰, H-6b), 3.51 (s, 3H, CH₃O), 3.47 (s, 3H,

CH₃O), 3.36 (dd, 1H, J_2,32.9, J_3,48.9 Hz, H-3), 3.34 (ddd, 1H, J_4,5

9.5 Hz, J_5,61.6, 6.8 Hz, H-5), 3.28 (dd, 1H, J_3,4ꢂ J_4,59.2 Hz, H-4),

1.95 (s, 3H, CH₃C(O)O)); ¹³C NMR (125 MHz, CDCl₃) d 169.8

(C@O), 138.6 (Ar), 138.5 (Ar), 138.3 (Ar), 138.1 (Ar), 138.0 (Ar),

128.4 (Ar), 128.3(2) (Ar), 128.3(0) (Ar), 128.2 (Ar), 128.1 (Ar),

127.9 (Ar), 127.8 (Ar), 127.7 (Ar), 127.5(7) (Ar), 127.5(6) (Ar),

127.4(5) (Ar), 127.4 (Ar), 101.6, 101.1 (C-1, C-1⁰), 83.1 (C-3⁰), 79.9

(C-3), 78.0, 76.4, 75.7, 74.9, 74.8, 74.7, 73.5(4), 73.4(8), 73.3, 72.4,

70.7, 69.9, 69.7 (C-2⁰, C-4⁰, C-5⁰, C-6⁰, C-2, C-4, C-5, C-6,

PhCH₂O ꢃ 5), 61.0 (CH₃O), 56.6 (CH₃O), 21.0 (CH₃C(O)O); HRESIMS:

Calcd for C₅₁H₅₈O₁₂Na 885.3821. Found 885.3828.

0

7.40–7.42 (m, 2H, ArH), 7.22–7.37 (m, 21H, ArH), 7.17–7.18 (m,

2H, ArH), 5.06 (d, 1H, J_gem11.3 Hz, PhCH₂O), 4.86 (d, 1H, J_gem

10.9Hz, PhCH₂O), 4.79 (d, 1H, J_gem11.3 Hz, PhCH₂O), 4.78 (d, 1H,

J_gem12.5 Hz, PhCH₂O), 4.61 (d, 1H, J_gem12.0 Hz, PhCH₂O) 4.59 (d,

1H, J_{1 ,2}8.8Hz, H-1⁰), 4.56 (d, 1H, J_gem12.0 Hz, PhCH₂O), 4.52 (d,

1H, J_gem11.0 Hz, PhCH₂O), 4.51 (d, 1H, J_gem12.5Hz, PhCH₂O), 4.46

(d, 1H, J_gem12.0 Hz, PhCH₂O), 4.42 (d, 1H, J_gem12.0 Hz, PhCH₂O),

4.22 (s, 1H, H-1), 4.15 (d, 1H, J_2,32.5 Hz, H-2) 3.44–3.74 (m, 11H,

H-2⁰, H-3⁰, H-4⁰, H-5⁰, H-6a⁰, H-6b⁰, OH, H-3, H-5, H-6a, H-6b),

3.54 (s, 3H, CH₃O), 1.85 (ddd, 1H, J_3,4ꢂ J_gemꢂ J_4,512.5 Hz, H-4ax),

0

1.78 (ddd, 1H,

J C NMR

2.0, 4.6, J_gem12.4Hz, H-4eq); ¹³C¹³

(125 MHz, CDCl₃) d 139.1 (Ar), 138.3 (Ar), 138.2(3) (Ar), 138.1(8)

(Ar), 128.4 (Ar), 128.3(1) (Ar), 128.2(5) (Ar), 128.0 (Ar), 127.9

(Ar), 127.7(3) (Ar), 127.6(9) (Ar), 127.6(8) (Ar), 127.6(5) (Ar),

127.5 (Ar), 127.4(4) (Ar), 127.3(9) (Ar), 104.5 (C-1⁰), 101.9 (C-1),

85.2, 77.4, 75.5, 75.4, 75.0, 74.7, 74.3, 74.1, 73.6, 73.4, 72.7, 72.1,

69.7, 69.3 (C-2⁰, C-3⁰, C-4⁰, C-5⁰, C-6⁰, C-2, C-3, C-5, C-6,

PhCH₂O ꢃ 5), 56.9 (CH₃O), 29.4 (C-4); HRESIMS: Calcd for

C₄₈H₅₄O₁₀Na 813.3609. Found 813.3608.

3.30. Methyl 3,4,6-tri-O-benzyl-b-

D-mannopyranosyl-(1?2)-

3.32. Methyl 3,4,6-tri-O-benzyl-b-D-glucopyranosyl-(1?2)-3,6-

3,6-di-O-benzyl-4-deoxy-b- -lyxo-hexopyranoside (33)

D

di-O-benzyl-4-O-methyl-b- -mannopyranoside (35)

D

Disaccharide 32 (312 mg, 0.39 mmol) was dissolved in Me₂SO

(5 mL), Ac₂O (2.5 mL) was added, and the reaction mixture was

stirred overnight, then concentrated under reduced pressure. The

residue was redissolved in dry THF (5 mL), and the solution was

cooled to ꢀ78 °C. L-Selectride^Ò(1.7 mL, 1.0 M in THF) was added

dropwise, and the reaction was allowed to slowly warm to room

temperature. The reaction was quenched with MeOH and concen-

trated under reduced pressure. Puriﬁcation by column chromatog-

raphy over silica gel (7:3 hexanes–EtOAc) gave 33 (200 mg, 65%) as

Disaccharide 34 (511 mg, 0.59 mmol) was dissolved in 1:1

CH₂Cl₂–MeOH (10 mL) and treated with 0.5 M CH₃ONa–CH₃OH

(5 mL), then processed as described for 18. Puriﬁcation of the prod-

uct by chromatography over silica gel (7:3 hexanes–EtOAc) gave

35 (470 mg, 97%) as a clear syrup: R_f0.38 (1:1 hexanes–EtOAc);

[a

]

D

ꢀ52 (c 0.20, CHCl₃); ¹H NMR (500 MHz, CDCl₃) d 7.24–7.41

(m, 23H, ArH), 7.16–7.18 (m, 2H, ArH), 5.06 (d, 1H, J_gem11.3 Hz,

PhCH₂O), 4.84–4.87 (m, 2H, PhCH₂O), 4.78 (d, 1H, J_gem11.2 Hz,

0

PhCH₂O), 4.67 (d, 1H, J_gem12.1 Hz, PhCH₂O), 4.61 (d, 1H, J_{1 ,2}

a white solid: R_f0.28 (1:1 hexanes–EtOAc); [

a

]

_Dꢀ66 (c 0.73, CHCl₃)

7.6 Hz, H-1⁰), 4.59 (d, 1H, J_gem11.1 Hz, PhCH₂O), 4.56 (d, 1H, J_gem

11.9 Hz, PhCH₂O), 4.52 (d, 1H, J_gem11.0 Hz, PhCH₂O), 4.47 (d, 1H,

J_gem12.1 Hz, PhCH₂O), 4.44 (d, 1H, J_gem12.0 Hz, PhCH₂O), 4.27 (s,

1H, H-1), 4.19 (d, 1H, J_2,33.1 Hz, H-2), 3.78 (dd, 1H, J_5,62.1, J_gem

10.9Hz, H-6a), 3.73 (dd, 1H, J_5,65.1, J_gem11.0 Hz, H-6b), 3.49–3.72

(m, 7H, H-2⁰, H-3⁰, H-4⁰, H-5⁰, H-6a⁰, H-6b⁰, H-4), 3.52 (s, 6H,

CH₃O ꢃ 2), 3.41 (dd, 1H, J_2,33.2, J_3,49.3 Hz, H-3), 3.32 (ddd, 1H,

J_4,59.5, J_5,62.0,4.9Hz, H-5), 3.31 (br s, 1H, OH); ¹³C NMR

(125 MHz, CDCl₃) d 139.1 (Ar), 138.4 (Ar), 138.2(5) (Ar), 138.1(8)

(Ar), 138.1(7) (Ar), 128.3(1) (Ar), 128.2(8) (Ar), 128.2 (Ar), 128.0

(Ar), 127.9(4) (Ar), 127.9(0) (Ar), 127.7 (Ar), 127.6(4) (Ar),

127.6(3) (Ar), 127.5 (Ar), 127.4 (Ar), 104.2 (C-1⁰), 101.5 (C-1),

85.2 (C-3⁰), 80.1 (C-3), 77.1 (C-5⁰), 76.0, 75.8 (C-4, C-5), 75.4, 75.3,

75.0, 74.8, 74.7 (C-2, C-2⁰, C-4⁰, PhCH₂O ꢃ 2), 73.5 (PhCH₂O), 73.4

(PhCH₂O), 70.4 (PhCH₂O), 69.7 (C-6⁰), 69.4 (C-6), 61.0 (CH₃O),

57.1 (CH₃O); HRESIMS: Calcd for C₄₉H₅₆O₁₁Na 843.3715. Found

843.3719. Anal. Calcd for C₄₉H₅₆O₁₁: C, 71.69; H, 6.88. Found: C,

71.48; H, 7.09.

¹H NMR (500 MHz, CDCl₃) d 7.21–7.41 (m, 25H, ArH), 4.95 (d, 1H,

J_gem11.1 Hz, PhCH₂O), 4.93 (d, 1H, J_{1 ,2}0.7 Hz, H-1⁰), 4.87 (d, 1H,

J_gem11.4 Hz, PhCH₂O), 4.83 (d, 1H, J_gem12.2 Hz, PhCH₂O), 4.64 (d,

1H, J_gem12.1Hz, PhCH₂O), 4.60 (d, 1H, J_gem11.9 Hz, PhCH₂O), 4.55

(d, 1H, J_gem12.0 Hz, PhCH₂O), 4.54 (d, 1H, J_gem11.0Hz, PhCH₂O),

4.45 (d, 1H, J_2,32.7 Hz, H-2), 4.41 (d, 1H, J_gem11.5 Hz, PhCH₂O),

0

4.38–4.43 (m, 2H, PhCH₂O), 4.33 (d, 1H, J_{2 ,3}2.8 Hz, H-2⁰), 4.21

0

(d, 1H, J_1,20.7Hz, H-1), 3.88 (dd, 1H, J_{3 ,4}ꢂ J_{4 ,5}9.3 Hz, H-4⁰), 3.75

0

(dd, 1H, J_{5 ,6}1.8, J_gem10.5 Hz, H-6a⁰), 3.66 (dd, 1H, J_5,65.9, J_gem

9.6Hz, H-6a), 3.47–3.62 (m, 6H, H-3⁰, H-5⁰, H-6b⁰, H-3, H-5, H-6b),

3.50 (s, 3H, CH₃O), 2.74 (br s, 1H, OH), 1.74–1.85 (m, 2H, H-4ax,

H-4eq); ¹³C NMR (125 MHz, CDCl₃) d 138.5 (Ar), 138.2(2) (Ar),

138.2(1) (Ar), 138.1(7) (Ar), 138.1(5) (Ar), 128.3(9) (Ar), 128.3(6)

(Ar), 128.3(5) (Ar), 128.3(0) (Ar), 128.2(7) (Ar), 128.1 (Ar), 128.0

(Ar), 127.9 (Ar), 127.7(0) (Ar), 127.6(8) (Ar), 127.6(4) (Ar),

127.5(9) (Ar), 127.5(8) (Ar), 127.5(3) (Ar), 127.4(7) (Ar), 102.7 (C-

1), 98.8 (C-1⁰), 81.4 (C-3⁰), 75.0(9), 75.0(5), 74.5, 74.0, 73.6, 73.3,

72.8 (C-3, C-6, C-4⁰, C-5⁰, PhCH₂O ꢃ 3), 72.0 (C-5), 70.7 (PhCH₂O),

70.0 (C-6⁰), 69.2 (PhCH₂O), 68.7 (C-2), 67.7 (C-2⁰), 57.1 (CH₃O),

29.7 (C-4); HRESIMS: Calcd for C₄₈H₅₄O₁₀Na 813.3609. Found

813.3609.

0

3.33. Methyl 3,4,6-tri-O-benzyl-b-D-mannopyranosyl-(1?2)-

3,6-di-O-benzyl-4-O-methyl-b- -mannopyranoside (36)

D

As described for compound 19, disaccharide 35 (446 mg,

0.54 mmol) was dissolved in freshly distilled Me₂SO (10 mL) and

Ac₂O (5 mL). The concentrated reaction mixture was then treated

with 1.0 M L-Selectride^Òin THF (2.2 mL, 2.17 mmol) in dry THF

(10 mL) at ꢀ78 °C under argon. Puriﬁcation by column chromatog-

raphy over silica gel (7:3 hexanes–EtOAc) gave 36 (273 mg, 61%) as

3.31. Methyl 2-O-acetyl-3,4,6-tri-O-benzyl-b-

D-glucopyranosyl-

(1?2)-3,6-di-O-benzyl-4-O-methyl-b- -mannopyranoside (34)

D

Monosaccharide acceptor 30 (238 mg, 0.44 mmol) was reacted

with 2-O-acetyl-3,4,6-tri-O-benzyl-b- -glucopyranosyl trichloro-

acetimidate (16) (469 mg, 0.74 mmol) in CH₂Cl₂(5 mL) using

TMSOTf (7 L, 0.04 mmol) under argon at 0 °C, then processed as

D

a white solid: R_f0.29 (1:1 hexanes–EtOAc); [

a

]

D

ꢀ60 (c 0.47,

l

CHCl₃); ¹H NMR (600 MHz, CDCl₃) d 7.21–740 (m, 25H, ArH),

566

C. M. Nycholat, D. R. Bundle / Carbohydrate Research 344 (2009) 555–569

4.94 (d, 1H, J_gem10.9 Hz, PhCH₂O), 4.89–4.90 (m, 2H, H-1⁰, PhCH₂O),

4.82 (d, 1H, J_gem12.1 Hz, PhCH₂O), 4.66 (d, 1H, J_gem12.1 Hz,

PhCH₂O), 4.63 (d, 1H, J_gem12.0Hz, PhCH₂O), 4.57 (d, 1H, J_gem

12.0 Hz, PhCH₂O), 4.54 (d, 1H, J_gem11.0 Hz, PhCH₂O), 4.41–4.48

H-1), 3.63 (dd, 1H, J_2,3ꢂ J_3,48.8 Hz, H-3), 3.49–3.58 (m, 3H, H-2,

H-4, H-5), 3.55 (s, 3H, CH₃O), 3.03 (s, 3H, CH₃S(O)₂O), 2.37 (d, 1H,

J_1,22.2 Hz, OH); ¹³C NMR (125 MHz, CDCl₃) d 138.3 (Ar), 137.5

(Ar), 128.5(8) (Ar), 128.5(4) (Ar), 128.2 (Ar), 128.1 (Ar), 127.9(4)

(Ar), 127.8(9) (Ar), 103.7 (C-1), 84.1 (C-3), 76.7 (C-4), 75.2(2)

(PhCH₂O), 75.1(7) (PhCH₂O), 74.6 (C-2), 73.1 (C-5), 68.3 (C-6),

57.3 (CH₃O), 37.7 (CH₃S(O)₂O); HRESIMS: Calcd for C₂₂H₂₈O₈SNa

475.1397. Found 475.1395.

(m, 4H, H-2, 3(PhCH₂O)), 4.31 (dd, 1H, J_{1 ,2}0.7, J_{2 ,3}3.0 Hz, H-2⁰),

0

4.26 (d, 1H, J_1,20.6Hz, H-1), 3.88 (dd, 1H, J_{3 ,4}ꢂ J_{4 ,5}9.5 Hz, H-4⁰),

0

3.78 (dd, 1H, J_5,62.1, J_gem10.9 Hz, H-6a), 3.75 (dd, 1H, J_{5 ,6}2.0, J_gem

10.4 Hz, H-6a⁰), 3.73 (dd, 1H, J_5,65.4, J_gem10.8Hz, H-6b), 3.62 (dd,

1H, J_{5 ,6}6.2, J_gem10.6 Hz, H-6b⁰), 3.56 (dd, 1H, J_{2 ,3}3.0, J_{3 ,4}

0

9.1 Hz, H-3⁰), 3.47–3.52 (m, 2H, H-5⁰, H-4), 3.49 (s, 3H, CH₃O),

3.48 (s, 3H, CH₃O), 3.43 (dd, 1H, J_2,33.3, J_3,49.2Hz, H-3), 3.33

(ddd, 1H, J_4,59.6, J_5,61.9, 5.4 Hz, H-5); ¹³C NMR (125 MHz, CDCl₃)

d 138.4(4) (Ar), 138.3(6) (Ar), 138.3 (Ar), 138.2 (Ar), 138.1 (Ar),

128.4 (Ar), 128.3(1) (Ar), 128.2(6) (Ar), 128.1 (Ar), 128.0 (Ar),

127.9 (Ar), 127.8 (Ar), 127.7 (Ar), 127.6 (Ar), 127.5(4) (Ar),

127.5(3) (Ar), 127.4 (Ar), 102.1 (C-1), 99.1 (C-1⁰), 81.5 (C-3⁰), 80.1

(C-3), 75.9, 75.7, 75.1, 75.0, 74.4 (C-4, C-5, C-4⁰, C-5⁰, PhCH₂O),

73.5 (PhCH₂O), 73.4 (PhCH₂O), 70.7 (PhCH₂O), 70.3 (C-2), 69.9(7),

69.9(6), 69.6 (C-6, C-6⁰, PhCH₂O), 67.7 (C-2⁰), 60.9 (CH₃O), 57.2

(CH₃O); HRESIMS: Calcd for C₄₉H₅₆O₁₁Na 843.3715. Found

843.3716.

3.36. Methyl 3,4-di-O-benzyl-6-deoxy-b-D-glucopyranoside (40)

To a solution of 39 (370 mg, 0.82 mmol) in DMF (8 mL) was

added NaBH₄(309 mg, 8.2 mmol). The mixture was heated at

80 °C for 3 h. The reaction was diluted with CH₂Cl₂and washed

with 2% aq citric acid, distilled water and brine, then dried

(Na₂SO₄) and concentrated under reduced pressure. Puriﬁcation

by chromatography over silica gel (1:1 hexanes–EtOAc) gave 40

(235 mg, 80%) as a white solid: R_f0.48 (1:1 hexanes–EtOAc); [a]

D

ꢀ16 (c 1.0, CHCl₃); ¹H NMR (600 MHz, CDCl₃) d 7.28–7.40 (m,

10H, ArH), 4.93 (d, 1H, J_gem11.3 Hz, PhCH₂O), 4.90 (d, 1H, J_gem

10.9 Hz, PhCH₂O), 4.87 (d, 1H, J_gem11.3Hz, PhCH₂O), 4.66 (d, 1H,

J_gem10.9 Hz, PhCH₂O), 4.17 (d, 1H, J_1,27.6 Hz, H-1), 3.56 (dd, 1H,

J_2,3ꢂ J_3,49.2Hz, H-3), 3.55 (s, 3H, CH₃O), 3.52 (ddd, 1H, J_1,27.6,

J_2,39.6, J_2,OH2.0 Hz, H-2), 3.44 (dq, 1H, J_4,59.5, J_5,66.3 Hz, H-5),

3.22 (dd, 1H, J_3,4ꢂ J_4,58.8 Hz, H-4), 2.35 (d, 1H, J_2,OH2.1 Hz, OH),

1.34 (d, 3H, J_5,66.2 Hz, CH₃); ¹³C NMR (125 MHz, CDCl₃) d 138.6

(Ar), 138.1 (Ar), 128.5 (Ar), 128.4 (Ar), 128.0 (Ar), 127.9 (Ar),

127.8 (Ar), 127.7 (Ar), 103.5 (C-1), 84.3 (C-3), 82.3 (C-4), 75.3,

75.1, 74.9 (C-2, PhCH₂O ꢃ 2), 71.5 (C-5), 57.1 (CH₃O), 17.9 (C-6);

HRESIMS: Calcd for C₂₁H₂₆O₅Na 381.1672. Found 381.1670. Anal.

Calcd for C₂₁H₂₆O₅: C, 70.37; H, 7.31. Found: C, 70.68; H, 7.19.

3.34. Methyl 3,4-di-O-benzyl-b-

D

-glucopyranoside (38)

-glucopyranoside

Methyl 3-O-benzyl-4,6-O-benzylidene-b-

D

(37)¹⁵(1.56 g, 4.19 mmol) in a ﬂame-dried ﬂask was dissolved in

dry CH₂Cl₂(20 mL) and cooled to 0 °C (ice-water bath) under

argon. A 1.0 M solution of BH₃ꢁTHF complex in THF (21 mL,

20.95 mmol) was added, followed by the dropwise addition of a

1.0 M solution of dibutylboron triﬂate (2.1 mL, 2.10 mmol). After

3 h, the reaction was quenched with MeOH, neutralized with

Et₃N, then concentrated under reduced pressure. Chromatography

over silica gel (1:1 hexanes–EtOAc) yielded 38 (1.30 g, 83%) as a

3.37. Methyl 3,4-di-O-benzyl-6-deoxy-b-D-mannopyranoside

white solid: R_f0.12 (1:1 hexanes–EtOAc); [

a

]_Dꢀ10 (c 0.25, CHCl₃);

(41)

¹H NMR (500 MHz, CDCl₃) d 7.28–7.40 (m, 10H, ArH), 4.93 (d, 1H,

J_gem11.3 Hz, PhCH₂O), 4.89 (d, 1H, J_gem11.0 Hz, PhCH₂O), 4.88 (d,

1H, J_gem11.3 Hz, PhCH₂O), 4.67 (d, 1H, J_gem10.9 Hz, PhCH₂O),

4.24 (d, 1H, J_1,27.8 Hz, H-1), 3.89 (ddd, 1H, J_5,62.7, J_gem12.0, J_6,OH

5.5 Hz, H-6a), 3.75 (ddd, 1H, J_5,64.4, J_gem12.0, J_6,OH8.0 Hz, H-6b),

3.60–3.62 (m, 2H, H-3, H-4), 3.56 (s, 3H, CH₃O), 3.50 (m, 1H, H-

2), 3.40 (ddd, 1H, J_4,59.2, J_5,62.8, 4.4 Hz, H-5), 2.45 (d, 1H, J_2,OH

2.3 Hz, C2-OH), 1.97 (dd, 1H, J_6,OH5.7, 8.0 Hz, C6-OH); ¹³C NMR

(125 MHz, CDCl₃) d 138.5 (Ar), 137.9 (Ar), 128.5 (Ar), 128.1 (Ar),

127.9(4) (Ar), 127.9(3) (Ar), 127.8(Ar), 103.8 (C-1), 84.3, 77.3 (C-

3, C-4), 75.4, 75.2, 75.1 (C-5, PhCH₂O ꢃ 2), 74.6 (C-2), 61.9 (C-6),

57.3 (CH₃O); HRESIMS: Calcd for C₂₁H₂₆O₆Na 397.1622. Found

397.1619. Anal. Calcd for C₂₁H₂₆O₆: C, 67.36; H, 7.00. Found: C,

67.10; H, 7.02.

Compound 40 (362 mg, 1.01 mmol) was dissolved in a mixture

of Me₂SO (6 mL) and Ac₂O (3 mL). After stirring overnight at room

temperature, the reaction was concentrated under reduced pres-

sure. The remaining residue was dissolved in a mixture of 1:1

CH₂Cl₂–MeOH (10 mL) and cooled to 0 °C (ice-water bath). NaBH₄

(192 mg, 5.05 mmol) was added, and the reaction mixture was al-

lowed to slowly warm to room temperature. After 3 h, the reaction

was diluted with CH₂Cl₂and washed with 2% aq citric acid, dis-

tilled water and brine. The organic phase was dried (Na₂SO₄), then

concentrated under reduced pressure. Chromatography over silica

gel (7:3 hexanes–EtOAc) yielded 41 (320 mg, 88%) as a white solid:

R_f0.27 (1:1 hexanes–EtOAc); [

a]

ꢀ36 (c 1.0, CHCl₃); ¹H NMR

D

(600 MHz, CDCl₃) d 7.29–7.39 (m, 10H, ArH), 4.95 (d, 1H, J_gem

10.9 Hz, PhCH₂O), 4.77 (d, 1H, J_gem11.9 Hz, PhCH₂O), 4.69 (d, 1H, J_gem

11.9 Hz, PhCH₂O), 4.66 (d, 1H, J_gem10.9 Hz, PhCH₂O), 4.30 (d, 1H,

J_1,21.1 Hz, H-1), 4.10 (m, 1H, H-2), 3.51–3.55 (m, 5H, H-3, H-4,

CH₃O), 3.33 (dq, 1H, J_4,59.8, J_5,66.0 Hz, H-5), 2.37 (br s, 1H, OH),

1.36 (d, 3H, J_5,66.2 Hz, CH₃); ¹³C NMR (125 MHz, CDCl₃) d 138.4

(Ar), 137.9 (Ar), 128.5 (Ar), 128.4 (Ar), 128.1 (Ar), 127.9(1) (Ar),

127.8(8) (Ar), 127.7 (Ar), 100.6 (C-1), 81.4, 79.7 (C-3, C-4), 75.5

(PhCH₂O), 71.4(7), 71.4(6) (C-5, PhCH₂O), 68.4 (C-2), 56.9 (CH₃O),

17.9 (C-6); HRESIMS: Calcd for C₂₁H₂₆O₅Na 381.1672. Found

381.1672. Anal. Calcd for C₂₁H₂₆O₅: C, 70.37; H, 7.31. Found: C,

70.59; H, 7.38.

3.35. Methyl 3,4-di-O-benzyl-6-O-methanesulfonyl-b-D-

glucopyranoside (39)

Compound 38 (489 mg, 1.31 mmol) was dissolved in dry CH₂Cl₂

(5 mL) and dry pyridine (5 mL), and the mixture was cooled to 0 °C

(ice-water bath) under argon. Methanesulfonyl chloride (152 lL,

1.96 mmol) was added dropwise, and the reaction was stirred

overnight. The reaction mixture was diluted with CH₂Cl₂and

washed with 1 M aq HCl, satd aq NaHCO₃, distilled water and

brine, then dried (Na₂SO₄) and concentrated under reduced pres-

sure. Chromatography over silica gel (1:1, toluene–EtOAc) yielded

39 (389 mg, 66%) as a white solid: R_f0.23 (1:1 hexanes–EtOAc);

3.38. Methyl 2-O-benzoyl-3,4-di-O-benzyl-b-D-glucopyranoside

(43)

[

a

]

ꢀ17 (c 0.34 CHCl₃); ¹H NMR (500 MHz, CDCl₃) d 7.29–7.40

D

(m, 10H, ArH), 4.96 (d, 1H, J_gem11.3 Hz, PhCH₂O), 4.92 (d, 1H, J_gem

10.8 Hz, PhCH₂O), 4.87 (d, 1H, J_gem11.3 Hz, PhCH₂O), 4.65 (d, 1H,

J_gem10.8 Hz, PhCH₂O), 4.47 (dd, 1H, J_5,61.7, J_gem11.1Hz, H-6a),

4.37 (dd, 1H, J_5,64.2, J_gem11.2 Hz, H-6b), 4.21 (d, 1H, J_1,27.7 Hz,

Methyl 2-O-benzoyl-3-O-benzyl-4,6-O-benzylidene-b-D-gluco-

pyranoside (42)²³(1.28 g, 2.68 mmol) in a ﬂame-dried ﬂask was

dissolved in dry CH₂Cl₂(20 mL) and cooled to 0 °C (ice-water bath)

C. M. Nycholat, D. R. Bundle / Carbohydrate Research 344 (2009) 555–569

567

under argon. A 1.0 M solution of BH₃ꢁTHF complex in THF (13.4 mL,

13.43 mmol) was added, followed by the dropwise addition of a

1.0 M solution of dibutylboron triﬂate (1.3 mL, 1.34 mmol). After

2 h, the reaction was quenched with MeOH, neutralized with

Et₃N and then concentrated under reduced pressure. Chromatogra-

phy over silica gel (7:3 hexanes–EtOAc) yielded 43 (1.03 g, 80%) as

(d, 1H, J_1,27.6 Hz, H-1), 3.66 (dd, 1H, J_5,62.2, J_gem10.8, H-6a),

3.57–3.63 (m, 3H, H-3, H-4, H-6b), 3.56 (s, 3H, CH₃O), 3.53 (ddd,

1H, J_2,OH2.0, J_1,2ꢂ J_2,37.9 Hz, H-2), 3.45 (ddd, 1H, J_4,59.3, J_5,62.1,

4.1 Hz, H-5), 3.39 (s, 3H, CH₃O), 2.35 (d, 1H, J_2,OH2.1 Hz, OH); ¹³C

NMR (125 MHz, CDCl₃) d 138.6 (Ar), 138.2 (Ar), 128.5 (Ar), 128.0

(Ar), 127.9 (Ar), 127.8 (Ar), 127.7 (Ar), 103.7 (C-1), 84.4 (C-3),

77.5 (C-4), 75.1, 75.0(2), 75.0(0) (C-5, PhCH₂O ꢃ 2), 74.6 (C-2),

71.2 (C-6), 59.4 (CH₃O), 57.2 (CH₃O); HRESIMS: Calcd for

C₂₂H₂₈O₆Na 411.1778. Found 411.1775; Anal. Calcd for C₂₂H₂₈O₆:

C, 68.02; H, 7.27. Found: C, 68.11; H, 7.39.

a white solid: R_f0.29 (1:1 hexanes–EtOAc); [

a

]

D

+39 (c 0.65.

CHCl₃); ¹H NMR (500 MHz, CDCl₃) d 8.02–8.04 (m, 2H, ArH), 7.57

(m, 1H, ArH) 7.43–7.46 (m, 2H, ArH), 7.29–7.37 (m, 5H, ArH),

7.14 (br s, 5H, ArH), 5.25 (dd, 1H, J_1,28.0, J_2,39.3 Hz, H-2), 4.88

(d, 1H, J_gem11.0 Hz, PhCH₂O), 4.76 (d, 1H, J_gem11.1 Hz, PhCH₂O),

4.69 (m, 2H, PhCH₂O), 4.50 (d, 1H, J_1,28.0 Hz, H-1), 3.93 (ddd, 1H,

J_6,OH5.6, J_5,62.8, J_gem12.0 Hz, H-6a), 3.86 (dd, 1H, J_2,3ꢂ J_3,49.1 Hz,

H-3), 3.78 (ddd, 1H, J_6,OH8.0, J_5,64.5, J_gem12.3 Hz, H-6b), 3.73

(dd, 1H, J_3,49.0, J_4,59.5 Hz, H-4), 3.48 (ddd, 1H, J_4,59.4, J_5,62.7,

4.4 Hz, H-5), 3.48 (s, 3H, CH₃O), 1.93 (dd, 1H, OH); ¹³C NMR

(125 MHz, CDCl₃) d 165.2 (C@O), 137.8 (Ar), 137.7 (Ar), 133.1

(Ar), 129.9 (Ar), 129.8 (Ar), 128.5 (Ar), 128.4 (Ar), 128.3 (Ar),

128.1 (Ar), 128.0(0) (Ar), 127.9(7) (Ar), 127.7 (Ar), 102.1 (C-1),

82.6 (C-3), 77.7 (C-4), 75.4, 75.1(2), 75.0(8) (C-5, PhCH₂O ꢃ 2),

73.7 (C-2), 61.9 (C-6), 57.0 (CH₃O); HRESIMS: Calcd for C₂₈H₃₀O₇Na

501.1884. Found 501.1886; Anal. Calcd for C₂₈H₃₀O₇: C, 70.28; H,

6.32. Found: C, 70.30; H, 6.45.

3.41. Methyl 3,4-di-O-benzyl-6-O-methyl-b-D-

mannopyranoside (46)

Compound 45 (600 mg, 1.54 mmol) was dissolved in a mixture

of Me₂SO (5 mL) and Ac₂O (5 mL). After stirring overnight at room

temperature, the reaction was concentrated under reduced pres-

sure. The remaining residue was dissolved in a mixture of 1:1

CH₂Cl₂–MeOH (10 mL) and cooled to 0 °C (ice-water bath). NaBH₄

(294 mg, 7.72 mmol) was added, and the reaction mixture was al-

lowed to slowly warm to room temperature. After 3 h, the reaction

mixture was diluted with CH₂Cl₂and washed with 2% aq citric acid,

distilled water and brine. The organic phase was dried (Na₂SO₄),

and then concentrated under reduced pressure. Chromatography

over silica gel (7:3 hexanes–EtOAc) yielded 46 (508 mg, 85%) as a

3.39. Methyl 2-O-benzoyl-3,4-di-O-benzyl-6-O-methyl-b-D-

glucopyranoside (44)

white solid: R_f0.14 (1:1 hexanes–EtOAc); [

a

]

ꢀ27 (c 0.6, CHCl₃);

D

¹H NMR (500 MHz, CDCl₃) d 7.27–7.39 (m, 10H, ArH), 4.93 (d, 1H,

J_gem10.9 Hz, PhCH₂O), 4.78 (d, 1H, J_gem11.9 Hz, PhCH₂O), 4.69 (d,

1H, J_gem11.9 Hz, PhCH₂O), 4.62 (d, 1H, J_gem11.0 Hz, PhCH₂O), 4.32

(d, 1H, J_1,21.0 Hz, H-1), 4.09 (m, 1H, J_1,20.9, J_2,33.0 Hz, H-2), 3.88

(dd, 1H, J_3,4ꢂ J_4,59.4 Hz, H-4), 3.68 (dd, 1H, J_5,62.2, J_gem10.7 Hz,

H-6a), 3.63 (dd, 1H, J_5,65.0, J_gem10.6 Hz, H-6b), 3.57 (dd, 1H, J_2,3

3.1, J_3,49.1 Hz, H-3), 3.54 (s, 3H, CH₃O), 3.39 (s, 3H, CH₃O), 3.38

(ddd, 1H, J_4,59.6, J_5,62.1, 4.9 Hz, H-5), 2.38 (d, 1H, J_2,OH2.3 Hz,

OH); ¹³C NMR (125 MHz, CDCl₃) d 138.4 (Ar), 137.9 (Ar), 128.5

(Ar), 128.4 (Ar), 128.1 (Ar), 127.8(8) (Ar), 127.8(4) (Ar), 127.7(6)

(Ar), 100.8 (C-1), 81.4 (C-3), 75.2(1) (PhCH₂O), 75.1(5) (C-5), 74.2

(C-4), 71.5(4), 71.4(7) (C-6, PhCH₂O), 68.3 (C-2), 59.4 (CH₃O), 56.9

(CH₃O); HRESIMS: Calcd for C₂₂H₂₈O₆Na 411.1778. Found

411.1782.

To a solution of compound 43 (953 mg, 1.99 mmol) in dry DMF

(20 mL) was added methyl iodide (248 L, 3.98 mmol). The reac-

l

tion was cooled to 0 °C (ice-water bath) under argon before the

addition of NaH (159 mg, 3.98 mmol). After 3 h stirring at 0 °C,

the reaction was quenched with HOAc, then concentrated under

reduced pressure. Puriﬁcation by chromatography over silica gel

(4:1 hexanes–EtOAc) gave 44 (937 mg, 96%) as a white solid: R_f

0.51 (1:1 hexanes–EtOAc); [

a]

+34 (c 0.27, CHCl₃); ¹H NMR

D

(500 MHz, CDCl₃) d 8.02–8.04 (m, 2H, ArH), 7.57 (m, 1H, ArH),

7.42–7.45 (m, 2H, ArH), 7.29–7.37 (m, 5H, ArH), 7.13 (br s, 5H,

ArH), 5.27 (dd, 1H, J_1,28.0, J_2,39.2 Hz, H-2), 4.86 (d, 1H, J_gem

11.0 Hz, PhCH₂O), 4.75 (d, 1H, J_gem11.1 Hz, PhCH₂O), 4.64–4.69

(m, 2H, PhCH₂O), 4.45 (d, 1H, J_1,27.9 Hz, H-1), 3.84 (dd, 1H,

J_2,3ꢂ J_3,49.1 Hz, H-3), 3.76 (dd, 1H, J_3,4ꢂ J_4,59.4 Hz, H-4), 3.70

(ABX, 1H, J_5,64.6, J_gem10.8 Hz, H-6a), 3.66 (ABX, 1H, J_5,61.9, J_gem

10.8Hz, H-6b), 3.53 (ABX, 1H, J_4,59.7, J_5,61.9, 4.6 Hz, H-5), 3.47

(s, 3H, CH₃O), 3.42 (s, 3H, CH₃O); ¹³C NMR (125 MHz, CDCl₃) d

165.2 (C@O), 138.1 (Ar), 137.8 (Ar), 133.0 (Ar), 130.0 (Ar), 129.8

(Ar), 128.5 (Ar), 128.3 (Ar), 128.2 (Ar), 128.0 (Ar), 127.9(9) (Ar),

127.9(5) (Ar), 127.6 (Ar), 102.0 (C-1), 82.8 (C-3), 77.9 (C-4), 75.1,

75.0(4), 74.9(8) (C-5, PhCH₂O ꢃ 2), 73.7 (C-2), 71.2 (C-6), 59.5

(CH₃O), 56.7 (CH₃O); HRESIMS: Calcd for C₂₉H₃₂O₇Na 515.2040.

Found 515.2042. Anal. Calcd for C₂₉H₃₂O₇: C, 70.71; H, 6.55. Found:

C, 70.82; H, 6.64.

3.42. Methyl 2-O-acetyl-3,4,6-tri-O-benzyl-b-

D-glucopyranosyl-

(1?2)-3,4-di-O-benzyl-6-deoxy-b- -mannopyranoside (47)

D

Monosaccharide acceptor 41 (250 mg, 0.70 mmol) was reacted

with 2-O-acetyl-3,4,6-tri-O-benzyl-b- -glucopyranosyl trichloro-

acetimidate (16) (533 mg, 0.84 mmol) in CH₂Cl₂(5 mL) using

TMSOTf (8 L, 0.04 mmol) under argon at 0 °C, then processed as

D

l

described for 17. The product was puriﬁed by chromatography

over silica gel (4:1 hexanes–EtOAc) to give 47 (560 mg, 96%) as a

colourless syrup: R_f0.65 (1:1 hexanes–EtOAc); [

a

]

D

ꢀ43 (c 0.8,

CHCl₃); ¹H NMR (500 MHz, CDCl₃) d 7.19–7.39, (m, 25H, ArH),

5.13 (dd, 1H, J 8.1, 9.5 Hz, H-2⁰), 4.99 (d, 1H, J_gem10.8 Hz, PhCH₂O),

4.88 (d, 1H, J_gem12.1 Hz, PhCH₂O), 4.82–4.84 (m, 2H, H-1⁰, PhCH₂O),

4.80 (d, 1H, J_gem11.5 Hz, PhCH₂O), 4.76 (d, 1H, J_gem11.4 Hz,

PhCH₂O), 4.59 (d, 1H, J_gem10.8 Hz, PhCH₂O), 4.52–4.57 (m, 2H,

PhCH₂O), 4.51 (d, 1H, J_gem12.2 Hz, PhCH₂O), 4.48 (d, 1H, J_gem

12.1 Hz, PhCH₂O), 4.23 (d, 1H, J_2,32.8 Hz, H-2), 4.15 (s, 1H, H-1),

3.74–3.79 (m, 2H, H-3⁰, H-6a⁰), 3.55–3.67 (m, 3H, H-4⁰, H-5⁰, H-

6b⁰), 3.48 (dd, 1H, J_3,4ꢂ J_4,59.1 Hz, H-4), 3.43 (s, 3H, CH₃O), 3.41

(dd, 1H, J_3,49.3 Hz, H-3), 3.24 (dq, 1H, J_4,59.1, J_5,66.0 Hz, H-5),

2.03 (s, 3H, CH₃C(O)O), 1.32 (d, 3H, J_5,66.0 Hz, CH₃); ¹³C NMR

(125 MHz, CDCl₃) d 169.8 (C@O), 138.8 (Ar), 138.6 (Ar), 138.3

(Ar), 138.1 (Ar), 128.4 (Ar), 128.3(4) (Ar), 128.3(0) (Ar), 128.2

(Ar), 128.1(2) (Ar), 128.1(0) (Ar), 127.8 (Ar), 127.7 (Ar), 127.6

(Ar), 127.5 (Ar), 127.4 (Ar), 101.7 (C-1), 101.1 (C-1⁰), 83.1 (C-3⁰),

3.40. Methyl 3,4-di-O-benzyl-6-O-methyl-b-D-glucopyranoside

(45)

Compound 44 (937 mg, 1.90 mmol) was dissolved in a mixture

of 1:1 CH₂Cl₂–MeOH (20 mL). A 0.5 M solution of NaOMe in MeOH

(5 mL) was added, and the reaction was stirred at room tempera-

ture overnight. The reaction mixture was neutralized with Amber-

lite IR-120 (H⁺) resin, and ﬁltered, and the ﬁltrate was

concentrated under reduced pressure. Chromatography over silica

gel (1:1 hexanes–EtOAc) gave 45 (663 mg, 90%) as a white pow-

dery solid: R_f0.31 (1:1 hexanes–EtOAc); [

a

]

ꢀ15 (c 0.59, CHCl₃);

D

¹H NMR (500 MHz, CDCl₃) d 7.26–7.39 (m, 10H, ArH), 4.92 (d, 1H,

J_gem11.4 Hz, PhCH₂O), 4.88 (d, 1H, J_gem11.0 Hz, PhCH₂O), 4.87 (d,

1H, J_gem11.4 Hz, PhCH₂O), 4.63 (d, 1H, J_gem11.0 Hz, PhCH₂O), 4.18

568

C. M. Nycholat, D. R. Bundle / Carbohydrate Research 344 (2009) 555–569

79.9, 79.8 (C-3, C-4), 78.1 (C-4⁰), 75.5 (PhCH₂O), 75.0, 74.8, 74.7

(C-5⁰, PhCH₂O ꢃ 2), 73.6, 73.5 (C-2⁰, PhCH₂O), 72.5 (C-2), 71.7

(C-5), 69.9, 69.8 (C-6, PhCH₂O), 56.5 (CH₃O), 21.1 (CH₃C(O)O),

18.0 (C-6); HRESIMS: Calcd for C₅₀H₅₆O₁₁Na 855.3715. Found

855.3715.

(C-2⁰), 57.1 (CH₃O), 18.0 (C-6); HRESIMS: Calcd for C₄₈H₅₄O₁₀Na

813.3609. Found 813.3614. Anal. Calcd for C₄₈H₅₄O₁₀: C, 71.90;

H, 6.21. Found: C, 71.95; H, 6.22.

3.45. Methyl 2-O-acetyl-3,4,6-tri-O-benzyl-b-D-glucopyranosyl-

(1?2)-3,4-di-O-benzyl-6-O-methyl-b- -mannopyranoside (50)

D

3.43. Methyl 3,4,6-tri-O-benzyl-b-D-glucopyranosyl-(1?2)-3,4-

di-O-benzyl-6-deoxy-b- -mannopyranoside (48)

D

Monosaccharide acceptor 46 (198 mg, 0.51 mmol) was reacted

with 2-O-acetyl-3,4,6-tri-O-benzyl-b- -glucopyranosyl trichloro-

acetimidate (16) (390 mg, 0.61 mmol) in CH₂Cl₂(5 mL) using

TMSOTf (6 L, 0.03 mmol) under argon at 0 °C. The mixture was

D

Disaccharide 47 (529 mg, 0.63 mmol) was dissolved in 1:1

CH₂Cl₂–MeOH (20 mL) and treated with 0.5 M CH₃ONa–CH₃OH

(5 mL), then processed as described for 18. Puriﬁcation of the prod-

uct by chromatography over silica gel (7:3 hexanes–EtOAc) gave

48 (502 mg, quant.) as a colourless syrup: R_f0.49 (1:1 hexanes–

l

then processed as described for 17. The product was puriﬁed by

chromatography over silica gel (4:1 hexanes–EtOAc) to give 50

(298 mg, 68%) as a colourless syrup: R_f0.43 (1:1 hexanes–EtOAc);

EtOAc); [

a

]

ꢀ45 (c 0.57, CHCl₃); ¹H NMR (500 MHz, CDCl₃) d

D

[a]

_Dꢀ43 (c 0.47, CHCl₃); ¹H NMR (500 MHz, CDCl₃) d 7.18–7.37 (m,

7.24–7.44 (m, 23H, ArH), 7.17–7.19 (m, 2H, ArH), 5.09 (d, 1H, J_gem

11.3 Hz, PhCH₂O), 5.00 (d, 1H, J_gem10.8 Hz, PhCH₂O), 4.90 (d, 1H,

J_gem12.1Hz, PhCH₂O), 4.87 (d, 1H, J_gem10.9 Hz, PhCH₂O), 4.82 (d,

1H, J_gem11.3 Hz, PhCH₂O), 4.61 (d, 1H, J_gem10.8 Hz, PhCH₂O),

25H, ArH), 5.12 (dd, 1H, J_{1 ,2}8.1, J_{2 ,3}9.5 Hz, H-2⁰), 4.96 (d, 1H, J_gem

11.1 Hz, PhCH₂O), 4.89 (d, 1H, J_gem11.9 Hz, PhCH₂O), 4.82 (d, 1H,

0

J_gem11.5 Hz, PhCH₂O), 4.82 (d, 1H, J_{1 ,2}7.9 Hz, H-1⁰), 4.79 (d, 1H,

J_gem11.6 Hz, PhCH₂O), 4.75 (d, 1H, J_gem11.5 Hz, PhCH₂O), 4.55 (d,

1H, J_gem10.9 Hz, PhCH₂O), 4.53 (d, 1H, J_gem10.9 Hz, PhCH₂O), 4.52

(d, 1H, J_gem11.9Hz, PhCH₂O), 4.48 (d, 1H, J_gem12.1 Hz, PhCH₂O),

4.46 (d, 1H, J_gem11.9 Hz, PhCH₂O), 4.23 (d, 1H, J_2,32.9 Hz, H-2),

0

4.59 (d, 1H, J_{1 ,2}7.9 Hz, H-1⁰), 4.56 (d, 1H, J_gem12.4 Hz, PhCH₂O),

4.54 (d, 1H, J_gem11.1 Hz, PhCH₂O), 4.49 (d, 1H, J_gem12.1 Hz,

PhCH₂O), 4.45 (d, 1H, J_gem12.0 Hz, PhCH₂O), 4.27 (s, 1H, H-1),

0

4.22 (d, 1H, J_2,33.0 Hz, H-2), 3.75 (dd, 1H, J_{2 ,3}9.0 Hz, H-2⁰), 3.64–

3.72 (m, 3H, H-3⁰, H-6a⁰, H-6b⁰), 3.52–3.59 (m, 3H, H-4⁰, H-5⁰, H-

4), 3.52 (s, 3H, CH₃O), 3.49 (dd, 1H, J_2,33.1, J_3,49.3 Hz, H-3), 3.31

(dq, 1H, J_4,59.0, J_5,66.1 Hz, H-5), 1.37 (d, 3H, J_5,66.1 Hz, CH₃); ¹³C

NMR (125 MHz, CDCl₃) d 139.1 (Ar), 138.6 (Ar), 138.3 (Ar), 138.2

(Ar), 138.1 (Ar), 128.3(4) (Ar), 128.3(0) (Ar), 128.2(8) (Ar),

128.0(7) (Ar), 128.0(6) (Ar), 127.9(6) (Ar), 127.8 (Ar), 127.6(8)

(Ar), 127.6(5) (Ar), 127.5(4) (Ar), 127.5(3) (Ar), 127.4 (Ar), 104.7

(C-1⁰), 101.3 (C-1), 85.3 (C-3⁰), 80.1, 79.9 (C-3, C-4), 77.3 (C-4⁰, C-

5⁰), 75.5(3), 75.5(2), 75.5(0) (C-2, C-2⁰, PhCH₂O), 75.3 (PhCH₂O),

75.0 (PhCH₂O), 74.8 (C-4⁰, C-5⁰), 73.4 (PhCH₂O), 71.8 (C-5), 70.4

(PhCH₂O), 69.7 (C-6⁰), 57.0 (CH₃O), 18.0 (C-6); HRESIMS: Calcd

for C₄₈H₅₄O₁₀Na 813.3609. Found 813.3609.

0

4.19 (s, 1H, H-1), 3.76 (dd, 1H, J_{2 ,3}8.2, J_{3 ,4}9.4Hz, H-3⁰), 3.74

0

(dd, 1H, J_{5 ,6}1.4, J_gem8.9 Hz, H-6a⁰), 3.53–3.66 (m, 6H, H-4⁰, H-5⁰,

H-6b⁰, H-4, H-6a, H-6b), 3.46–3.48 (m, 4H, H-3, CH₃O), 3.36–3.39

(m, 4H, H-5, CH₃O), 2.03 (s, 3H, CH₃C(O)O); ¹³C NMR (125 MHz,

CDCl₃) d 169.8 (C@O), 138.7 (Ar), 138.5 (Ar), 138.2 (Ar), 138.1

(Ar), 138.0 (Ar), 128.4 (Ar), 128.3(3) (Ar), 128.3(0) (Ar), 128.2(5)

(Ar), 128.1(3) (Ar), 128.0(9) (Ar), 128.0 (Ar), 127.8 (Ar), 127.7(2)

(Ar), 127.7(1) (Ar), 127.6 (Ar), 127.5(5) (Ar), 127.4(8) (Ar), 101.7

(C-1), 101.1 (C-1⁰), 83.2 (C-3⁰), 80.0 (C-3), 78.1 (C-4⁰/C-5⁰/C-4),

75.5, 75.2, 74.9, 74.8(2), 74.7(5) (C-4⁰/C-5⁰/C-4, C-5, PhCH₂O ꢃ 3),

73.6, 73.5, 72.8, 72.2 (C-2, C-6, C-2⁰, PhCH₂O), 69.8(4), 69.8(0) (C-

6⁰, PhCH₂O), 59.3 (CH₃O), 56.7 (CH₃O), 21.1 (CH₃C(O)O); HRESIMS:

Calcd for C₅₁H₅₈O₁₂Na 885.3821. Found 885.3811.

0

3.44. Methyl 3,4,6-tri-O-benzyl-b-D-mannopyranosyl-(1?2)-

3.46. Methyl 3,4,6-tri-O-benzyl-b-D-glucopyranosyl-(1?2)-3,4-

3,4-di-O-benzyl-6-deoxy-b- -mannopyranoside (49)

D

di-O-benzyl-6-O-methyl-b- -mannopyranoside (51)

D

As described for compound 19, disaccharide 48 (475 mg,

0.60 mmol) was dissolved in freshly distilled Me₂SO (10 mL)

and Ac₂O (5 mL). The concentrated reaction mixture was then

treated with 1.0 M L-Selectride^Òin THF (2.4 mL, 2.40 mmol) in

dry THF (10 mL) at ꢀ78 °C under argon. Puriﬁcation by column

chromatography over silica gel (1:1 hexanes–EtOAc) gave 49

(390 mg, 82%) as a white solid: R_f0.41 (1:1 hexanes–EtOAc);

Disaccharide 50 (281 mg, 0.33 mmol) was dissolved in 1:1

CH₂Cl₂–MeOH (10 mL) and treated with 0.5 M CH₃ONa–CH₃OH

(3 mL), then processed as described for 18. Puriﬁcation of the prod-

uct by chromatography over silica gel (7:3 hexanes–EtOAc) gave

51 (257 mg, 96%): R_f0.31 (1:1 hexanes–EtOAc); [

a

]

ꢀ42 (c 0.80,

D

CHCl₃); ¹H NMR (500 MHz, CDCl₃) d 7.23–7.43 (m, 23H, ArH),

7.16–7.18 (m, 2H, ArH), 5.08 (d, 1H, J_gem11.2 Hz, PhCH₂O), 4.97

(d, 1H, J_gem10.9 Hz, PhCH₂O), 4.90 (d, 1H, J_gem12.0 Hz, PhCH₂O),

4.86 (d, 1H, J_gem10.9 Hz, PhCH₂O), 4.80 (d, 1H, J_gem11.4 Hz,

[a

]

D

ꢀ52 (c 0.71, CHCl₃); ¹H NMR (500 MHz, CDCl₃) d 7.22–

7.24 (m, 25H, ArH), 4.96 (d, 1H, J_gem11.3 Hz, PhCH₂O), 4.94 (d,

1H, J_gem12.2 Hz, PhCH₂O), 4.93 (d, 1H, J_gem10.9 Hz, PhCH₂O),

PhCH₂O), 4.61 (d, 1H, J_{1 ,2}7.8 Hz, H-1⁰), 4.57 (d, 1H, J_gem10.9 Hz,

PhCH₂O), 4.55 (d, 1H, J_gem12.2 Hz, PhCH₂O), 4.53 (d, 1H, J_gem

11.0 Hz, PhCH₂O), 4.48 (d, 1H, J_gem12.1 Hz, PhCH₂O), 4.44 (d, 1H,

J_gem12.0 Hz, PhCH₂O), 4.28 (s, 1H, H-1), 4.23 (d, 1H, J_2,33.2 Hz,

4.90 (d, 1H, J_{1 ,2}0.7 Hz, H-1⁰), 4.85 (d, 1H, J_gem12.0 Hz, PhCH₂O),

4.65 (d, 1H, J_gem12.1 Hz, PhCH₂O), 4.60 (d, 1H, J_gem10.8 Hz,

PhCH₂O), 4.56 (d, 1H, J_gem11.0 Hz, PhCH₂O), 4.50 (d, 1H, J_2,3

2.8 Hz, H-2), 4.46 (d, 1H, J_gem11.4 Hz, PhCH₂O), 4.45 (d, 1H, J_gem

12.0 Hz, PhCH₂O), 4.42 (d, 1H, J_gem12.0 Hz, PhCH₂O), 4.34 (d, 1H,

0

H-2), 3.84 (dd, 1H, J_3,4ꢂ J_4,59.5 Hz, H-4), 3.73 (dd, 1H, J_{1 ,2}8.0,

J_{2 ,3}8.9 Hz, H-2⁰), 3.61–3.71 (m, 5H, H-3⁰, H-6a⁰, H-6b⁰, H-6a, H-

6b), 3.51–3.55 (m, 3H, H-4⁰, H-3, H-4), 3.53 (s, 3H, CH₃O), 3.39 (s,

3H, CH₃O), 3.37 (ddd, 1H, J_4,59.7, J_5,62.0, 5.2 Hz, H-5); ¹³C NMR

(125 MHz, CDCl₃) d 139.1 (Ar), 138.5 (Ar), 138.2 (Ar), 138.1(3)

(Ar), 138.1(1) (Ar), 128.3(5) (Ar), 128.3(2) (Ar), 128.3(0) (Ar),

128.2(5) (Ar), 128.1 (Ar), 128.0(4) (Ar), 128.0(3) (Ar), 127.9 (Ar),

127.8 (Ar), 127.7 (Ar), 127.6 (Ar), 127.5 (Ar), 127.4 (Ar), 104.4 (C-

1⁰), 101.6 (C-1), 85.2 (C-3⁰), 80.2 (C-3), 77.3 (C-4⁰/C-5⁰) 75.6, 75.5,

75.3, 75.0, 74.9, 74.8 (C-2⁰, C-4⁰/C-5⁰, C-2, C-5, PhCH₂O ꢃ 3), 74.4

(C-4), 73.4 (PhCH₂O), 71.7 (C-6), 70.4 (PhCH₂O), 69.7 (C-6⁰), 59.4

(CH₃O), 57.2 (CH₃O); HRESIMS: Calcd for C₄₉H₅₆O₁₁Na 843.3715.

Found 843.3718.

J_{2 ,3}2.8 Hz, H-2⁰), 4.26 (s, 1H, H-1), 3.91 (dd, 1H, J_{3 ,4}ꢂ J_{4 ,5}

0

9.3 Hz, H-4⁰), 3.76 (dd, 1H, J_{5 ,6}2.0, J_gem10.6 Hz, H-6a⁰), 3.63

0

(dd, 1H, J_{5 ,6}6.1, J_gem10.5 Hz, H-6b⁰), 3.58 (dd, 1H, H-3⁰), 3.44–

3.52 (m, 3H, H-5⁰, H-3, H-4), 3.48 (s, 3H, CH₃O), 3.31 (dq, 1H,

J_4,58.7, J_5,66.0 Hz, H-5), 1.37 (d, 3H, J_5,66.1 Hz, CH₃); ¹³C NMR

0

(125 MHz, CDCl₃)

d 138.4(9) (Ar), 138.4(5) (Ar), 138.2 (Ar),

138.1 (Ar), 128.4 (Ar), 128.3(1) (Ar), 128.2(8) (Ar), 128.2(1)

(Ar), 128.2(0) (Ar), 128.1 (Ar), 127.9(Ar), 127.7 (Ar), 127.6(4)

(Ar), 127.6(3) (Ar), 127.5(5) (Ar), 127.5(0) (Ar), 102.0 (C-1),

99.1 (C-1⁰), 81.4 (C-3⁰), 80.1 (C-3/C-5⁰), 79.4 (C-4), 75.4 (PhCH₂O),

75.1 (PhCH₂O), 75.0 (C-3/C-5⁰), 74.4 (C-4⁰), 73.4 (PhCH₂O), 71.8

(C-5), 70.7 (PhCH₂O), 70.4, 70.1, 70.0 (C-2, C-6⁰, PhCH₂O), 67.7

C. M. Nycholat, D. R. Bundle / Carbohydrate Research 344 (2009) 555–569

569

3.47. Methyl 3,4,6-tri-O-benzyl-b-

D-mannopyranosyl-(1?2)-

67.7 (C-2⁰), 59.2 (CH₃O), 57.2 (CH₃O); HRESIMS: Calcd for

3,4-di-O-benzyl-6-O-methyl-b- -mannopyranoside (52)

D

C₄₉H₅₆O₁₁Na 843.3715. Found 843.3705.

As described for compound 19, disaccharide 51 (257 mg,

0.31 mmol) was dissolved in freshly distilled Me₂SO (8 mL) and

Ac₂O (4 mL). The concentrated reaction mixture was then treated

with 1.0 M L-Selectride^Òin THF (1.3 mL, 1.25 mmol) in dry THF

(10 mL) at ꢀ78 °C under argon. Puriﬁcation by column chroma-

tography over silica gel (7:3 hexanes–EtOAc) gave 52 (200 mg,

Supplementary data

Supplementary data associated with this article can be found, in

the online version, at doi:10.1016/j.carres.2008.12.011.

78%) as a white solid: R_f0.25 (1:1 hexanes–EtOAc); [

a

]

ꢀ49

D

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ArH), 7.21–7.34 (m, 21H, ArH), 4.96 (d, 1H, J_gem11.0 Hz,

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PhCH₂O), 4.93 (d, 1H, J_gem10.7 Hz, PhCH₂O), 4.91 (d, 1H, J_{1 ,2}

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12.1 Hz, PhCH₂O), 4.64 (d, 1H, J_gem12.1 Hz, PhCH₂O), 4.56 (d, 1H,

J_gem10.9 Hz, PhCH₂O), 4.55 (d, 1H, J_gem11.0 Hz, PhCH₂O), 4.50 (d,

1H, J_2,33.1 Hz, H-2), 4.46 (d, 1H, J_gem11.5 Hz, PhCH₂O), 4.45 (d,

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4.34 (d, 1H, J_{2 ,3}2.9 Hz, H-2⁰), 4.27 (d, 1H, J_1,20.7 Hz, H-1),

0

3.90 (dd, 1H, J_{3 ,4}ꢂ J_{4 ,5}9.3 Hz, H-4⁰), 3.80 (dd, 1H, J_3,4ꢂ J_4,5

0

9.6 Hz, H-4), 3.76 (dd, 1H, J_{5 ,6}2.0, J_gem10.6 Hz, H-6a⁰), 3.67

0

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(dd, 1H, J_5,62.0, J_gem10.6 Hz, H-6a), 3.62 (dd, 1H, J_{5 ,6}6.0, J_gem

10.7 Hz, H-6b⁰), 3.61 (dd, 1H, J_5,65.2, J_gem10.7 Hz, H-6b), 3.56

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9.3Hz, H-3⁰), 3.49 (ddd, 1H, J_{4 ,5}9.7, J_{5 ,6}1.9, 6.1 Hz, H-5⁰), 3.48

(s, 3H, CH₃O), 3.38 (s, 3H, CH₃O), 3.36 (ddd, 1H, J_4,59.8, J_5,6

2.0, 5.2 Hz, H-5), 2.78 (br s, 1H, OH); ¹³C NMR (125 MHz, CDCl₃)

d38.4(8) (Ar), 138.4(6) (Ar), 138.2 (Ar), 138.1(4) (Ar), 138.1(1)

(Ar), 128.4 (Ar), 128.3(2) (Ar), 128.3(0) (Ar), 128.2(9) (Ar),

128.2(7) (Ar), 128.2 (Ar), 128.1 (Ar), 128.0 (Ar), 127.9 (Ar),

127.7 (Ar), 127.6(4) (Ar), 127.6(1) (Ar), 127.5(2) (Ar), 127.4(9)

(Ar), 102.2 (C-1), 99.0 (C-1⁰), 81.4 (C-3), 80.2 (C-3⁰), 75.3, 75.2,

75.1, 75.0 (C-5, C-5⁰, PhCH₂O ꢃ 2), 74.4 (C-4⁰), 73.9 (C-4), 73.4

(PhCH₂O), 71.6 (C-6), 70.6 (PhCH₂O), 70.1, 70.0 (C-6⁰, PhCH₂O),

0

Article Doi

Synthesis of monodeoxy and mono-O-methyl congeners of methyl β-d-mannopyranosyl-(1→2)-β-d-mannopyranoside for epitope mapping of anti-Candida albicans antibodies

DOI: 10.1016/j.carres.2008.12.011

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