Synthesis of |β-(1→2)-linked oligomannosides

FULL PAPER

DOI: 10.1002/ejoc.200801024

Synthesis of β-(1Ǟ2)-Linked Oligomannosides

Monika Poláková,^[a,b]Mattias U. Roslund,^[a]Filip S. Ekholm,^[a]Tiina Saloranta,^[a]and

Reko Leino*^[a]

Keywords: Carbohydrates / Asymmetric synthesis / Glycosylation / Oligosaccharides / NMR spectroscopy

β-(1Ǟ2)-Linked oligomannosides constitute an important

class of carbohydrate structures located on the cell surface of

several Candida species, including C. albicans. As a result

of the immunostimulating properties of such compounds, the

upscaling of their synthesis is relevant. In this paper, a highly

stereoselective synthesis of β-(1Ǟ2)-linked oligomannosides

was performed by further development of and modifications

to the methodologies described earlier in the literature. In

addition to the synthesis of fully deprotected β-(1Ǟ2)-linked

mannobiose and mannotriose, some preliminary modifica-

tions to the oligosaccharide core, resulting in close analogues

with biological potential, are presented. The fully depro-

tected products form potential targets for screening against

C. albicans and may also result in new model structures for

vaccine development.

Germany, 2009)

an estimated degree of polymerization of 2 to 7^[6]or 2 to

14.^[7]The β-(1Ǟ2) mannans of C. albicans are immunogenic

and elicit specific antibodies in humans and animals.^[8]

Branched α-(1Ǟ2) linked mannans in turn are promising

targets for anti-HIV vaccines and related immunogen de-

sign.^[9]Nevertheless, the natural sources seldom provide

sufficient amounts of complex oligosaccharides for evaluat-

ing their full biological potential. Accordingly, efficient syn-

thetic methodologies are required for producing enough

material for biological studies.

As a result of the biological properties of mannoside

oligomers and the associated synthetic challenges involved,

the construction of β-linked mannosides has received con-

siderable attention in recent years. Crich et al. developed

direct protocols for highly stereoselective β-mannosylation,

including the efficient construction of the β-(1Ǟ2)-,^[10]β-

(1Ǟ3)-,^[11]and β-(1Ǟ4)-,^[10]as well as the β-(1Ǟ3)-β-

(1Ǟ4)-^[12]linked mannopyranosides. In their work, the ster-

eoselective β-mannosylation is based on the activation of

the donor species (mannopyranosyl sulfoxides or thioglyco-

sides) with Tf₂O, which at low temperature yields an α--

mannopyranosyl triflate,^[13]which in turn reacts with the -

mannose-derived acceptor in an S_N2 fashion to provide the

desired β-mannopyranoside. In general, the structure of the

donor significantly influences the outcome and stereoselec-

tivity of the β-mannosylation reaction. The presence of a

4,6-O-benzylidene acetal in the donor provides sufficient

torsional rigidity to the pyranose ring necessary for high

selectivity of glycosylation.^[13a,13b,14]The introduction of

ether-type protecting groups at O-2 and O-3 has appeared

to be important as well. A series of nonparticipating pro-

tecting groups including benzyl, p-methoxybenzyl, naph-

thylmethyl, and silyl (TBDMS) ether groups were investi-

Introduction

In organic chemistry, the total synthesis of complex ma-

rine natural products is considered by many as the ultimate

proving ground for methodology development.^[1]In carbo-

hydrate chemistry, a similar definition is often associated

with the notoriously difficult, stereoselective construction

of glycosidic bonds in β-mannosides and β-mannosamines

and, in particular, the β-mannans (Figure 1).^[2]The prob-

lems in constructing the β-mannosidic linkages arise from

several intervening factors, including the greater thermo-

dynamic and kinetic preference for the α-mannoside as a

result of the anomeric effect.^[2,3]

Figure 1. α-Linked mannan (left) and β-linked mannan (right).

In nature, β-(1Ǟ2)-linked mannans are produced by the

genus Candida (e.g., C. albicans,^[4]C. glabrata^[5]) with the

homopolymers of β-1,2-oligomannosides typically having

[a] Laboratory of Organic Chemistry Åbo Akademi University,

20500 Åbo, Finland

Fax: +358-2-2154866

E-mail: reko.leino@abo.fi

[b] Institute of Chemistry, Slovak Academy of Sciences,

Dúbravska 9, 845 38 Bratislava, Slovakia

Supporting information for this article is available on the

WWW under http://ww w .eurjoc.org or from the author.

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Synthesis of β-(1Ǟ2)-Linked Oligomannosides

gated in order to improve the β-mannosylation selectiv- also involving a similar type of oxidation–reduction se-

ity.^[11,15]Recently, a sterically minimal propargyl ether pro- quence, was presented by Fraser-Reid et al.^[22]

tecting group was introduced at the O-2 position of the do-

In the present work, we further investigated the use of

nor unit.^[11a]The use of propargyl protection at O-2, to- a mannosyl donor with propargyl ether protection at O-2

gether with a benzyl ether at O-3 in the donor, resulted in combined with benzyl ether protection at O-3 for construc-

a considerable increase in the β-mannosylation selectivity. tion of, specifically, β-1,2-linked di- and trimannosides and

This donor was successfully employed for efficient con- their glycosides and close analogues. The synthesis and

struction of β-1,3-mannan.^[11b]

characterization of these compounds together with the

In more detail, the method developed by Crich for the evaluation of the influence of protective group strategy on

synthesis of β-1,2-linked mannans is based on the triflate the glycosylation stereoselectivity is elucidated. Some of the

activation of a 4,6-O-benzylidene mannopyranosyl sulfox- compounds prepared here are analogous or closely related

ide donor (bearing p-methoxybenzyl protection at O-2 and to those obtained by Crich and others. However, owing to

benzyl at O-3) in the presence of TTBP in CH₂Cl₂at the biological properties and potential of β-(1Ǟ2)-linked

–60 °C, followed by coupling with the acceptor at –78 °C. mannans in particular, we have specifically targeted the syn-

Regioselective deprotection of the p-methoxybenzyl group thesis of fully deprotected β-1,2-mannobiose and β-1,2-man-

provides a new acceptor. An octameric cyclohexyl-capped β- notriose, which are reported here for the first time by utiliza-

1,2-mannan was prepared by iteration of this procedure.^[10]tion of this synthesis strategy. The synthetic strategies devel-

An analogous approach to the synthesis of β-1,2-linked oli- oped earlier by others have thus been adapted, modified,

gomannans was reported by Mallet.^[4d]

and further developed for this specific purpose and are dis-

Another method for the construction of β-1,2-mannos- cussed in detail in the present context. Furthermore, we car-

1

idic linkages by employing anomeric sulfonium triflate as ried out full H and ¹³C NMR spectroscopic analysis and

the glycosylation species was described by Seeberger.^[16a]signal assignments of the final products and building blocks

Activation of the free anomeric hydroxy group by Ph₂SO/ thereof, including spectral simulations and accurate deter-

Tf₂O provides an anomeric sulfonium triflate, which is more minations of the coupling constants involved, which even

stable than the α-mannosyl triflate intermediate utilized by for most of the compounds described earlier, are reported

Crich. Glycosylation with these species requires higher reac- here for the first time.

tion temperatures and longer reaction times. The sulfoxide/

Tf₂O dehydrative coupling strategy provided β-1,2-disac-

Results and Discussion

charides in high yields with moderate-to-very-good β-selec-

tivities. Another one-pot glycosylation method using an an-

omeric hydroxy sugar as the donor and employing phthalic

anhydride and triflic anhydride as activating agents was re-

Synthesis of Glycoside Donors and Acceptors

The oligosaccharide synthesis commenced by prepara-

cently reported to proceed with perfect β-stereoselectivi- tion of donor 19 according to a method described previous-

ty.^[16b]ly.^[11b]Several acceptors were prepared by use of the step-

Successful approach to β-1,2-mannosides was also wise, selective protecting group strategies illustrated in

achieved by utilization of a perbenzylated thioglycoside do- Scheme 1. The benzyl (2) and allyl (3)^[23]tetra-O-acetyl α-

nor activated with dimethyl disulfide/triflic anhydride pro- -mannopyranosides were easily obtained in high yields

viding good selectivities (β:α Ͼ 9:1) in the construction of from the glycosylation reactions of the corresponding

disaccharides. Importantly, in this case, highly selective gly- alcohols with peracetylated mannose (1) promoted by

cosylation was observed without the use of 4,6-O-benzyl- BF₃·OEt₂. Our attempt to synthesize the analogous cyclo-

idene protection, previously considered as crucial for ob- hexyl tetra-O-acetyl α--mannopyranoside (8) by use of a

taining highly stereoselective coupling reactions.^[17]

similar strategy resulted in low yield. For synthesis of glyco-

Yet, alternatively, β-1,2-linked mannans can be con- side 8, two alternative procedures were developed. The

structed by forming a β-glucopyranosyl linkage followed by switch of the Lewis acid from BF₃·OEt₂to tin(IV) chlo-

epimerization at C-2 by an oxidation–reduction sequence. ride^[24]led to a moderate yield of desired mannoside 8 in

In the first reports, an ulosyl bromide was employed as a one step. An alternative procedure consisting of a three-step

donor,^[18]but this was later replaced by the more-stable glu- sequence was also developed. Compound 8 was successfully

copyranosyl trichloroacetimidate,^[19a]which is particularly prepared by reaction of imidate donor 7^[25,26]with cyclo-

useful especially in scale-up reactions. With this indirect ap- hexanol promoted by BF₃·OEt₂. Zemplén deprotection of

proach, excellent diastereoselectivity was observed in the re- acetylated glycosides 2, 3, and 8^[26]then provided the corre-

duction of β-ulopyranosides to β-mannopyranosides by sponding benzyl (4),^[27]allyl (5),^[28]and cyclohexyl (9)^[26]α-

using -selectride in the key step.^[19a,20]A series of glycocon- -mannopyranosides. Interestingly, in the present study, a

jugates was prepared by this method.^[19]By use of the same 92% yield of 4 was achieved over three steps, whereas by

approach, β-1,2-linked di- and trimannosides with inter res- straightforward Fischer glycosylation, yields ranging from

idues linked through the sulfur atom were likewise pre- 35%^[29]up to 87%^[30]were reported. For further conversion

pared. The introduction of sulfur to the molecule provides to acceptors, glycosides 4–6 and 9 were transformed into

glycoconjugates with enhanced stabilities towards chemical their 4,6-O-benzylidene derivatives 10,^[26,31]11,^[32]12,^[31]

and enzymatic hydrolysis.^[21]An orthoester-based strategy, and 13.^[26]Selective protection of the equatorial hydroxy

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871

M. Poláková, M. U. Roslund, F. S. Ekholm, T. Saloranta, R. Leino

FULL PAPER

Scheme 1. Reagents and conditions: (i) BF₃·OEt₂, BnOH/AllOH, CH₂Cl₂, room temp., 24 h, 2 (90%), 3 (82%); (ii) MeONa/MeOH, room

temp., 3 h, 4 (95%), 5 (89%); (iii) PhCH(OMe)₂, pTosOH, DMF, 60 °C, 200 mbar, 2 h, 10 (50%), 11 (51%), 12 (52%), 13 (54%); (iv) 1.

Bu₂SnO, toluene, 120 °C, 3 h, 2. BnBr, Bu₄NI, CsF, 120 °C, 3 h, 14 (88%), 15 (88%), 16 (89%), 17 (84%); (v) 1. NH₂NH₂.AcOH, DMF,

55 °C, 30 min, 2. Cl₃CCN, DBU, CH₂Cl₂, room temp., 1.5 h; (vi) C₆H₁₁OH, BF₃·OEt₂, CH₂Cl₂, room temp., 22 h, ref.^[26]; (vii) SnCl₄,

CH₂Cl₂, room temp., 16 h, 64%.

group by treatment with Bu₂SnO in toluene and then alky- acceptors. The acceptors were added dropwise over 15 min

lation of the 2,3-O-dibutylstannylene intermediate with and the reaction proceeded under continuous stirring at the

BnBr gave 3-O-benzylated acceptors 14,^[26,31]15,^[33]16,^[31]same temperature over a period of 1.75 h. In total, six ac-

17,^[26]and 18.^[11b,26]Of these, cyclohexyl acceptor 17 is a ceptors, 11–14, 18, and 21, were tested for formation of the

new building block for oligosaccharide synthesis β-1,2-linkage (Scheme 3). The glycosylation reactions

(Scheme 1). Another, however less effective, approach to proved to be highly stereoselective and provided exclusively

such acceptors, for example, compound 16, can be based β-1,2-linked disaccharides 22–27 in 72–87% yield. In the ¹H

on the ring opening of endo dibenzylidene derivatives, re- and ¹³C NMR spectra of these compounds, the characteris-

portedly yielding only 10% of the desired compound (based tic signals for 5-H and C-5 in the β-mannosides were ob-

on endo ylidene).^[34]

The synthesis of β--mannopyranoside 21 was ac- complete characterization see the Experimental Section).

served at approximately 3.3 and 68 ppm, respectively (for

complished by a direct approach over three steps from 19

(Scheme 2). Reaction of activated donor 19 with methanol

afforded exclusively corresponding β-glycoside 20. Removal

of the propargyl function gave desired acceptor 21 with β-

configuration at the anomeric center. A strategy for the syn-

thesis of 21 over four steps from methyl β--glucopyrano-

side by S_N2 epimerization to the corresponding β-manno-

pyranoside was reported recently.^[35]

Next, the propargyl ether group of selected disaccharides

22 and 24–27 was removed by using a two-step protocol.

Isomerization of the propargyl functionality with tBuOK

in dry THF for 5–6 h afforded the corresponding allenyl

ethers. The reaction can be followed by ¹H NMR spec-

troscopy, which provides a simple and efficient method for

the determination of the isomerization yield. The signal

from the alkynyl proton (-CH₂–CϵCH) appears as a broad

triplet (two almost identical coupling constants) with chem-

ical shifts of δ = 2.4–2.5 ppm in all compounds studied. In

the allenyl derivatives, this signal disappeared and a new

signal for the allenyl proton (-CH=C=CH₂) appeared as a

triplet at δ = 6.8–7.1 ppm (J = 5–6 Hz). In the second step,

oxidative cleavage with NMO/OsO₄in acetone/water^[11b,36]

provided disaccharides 28–32 with free hydroxy groups at

O-2, suitable as acceptors for further oligosaccharide syn-

thesis. In all cases, regioselective removal of the propargyl

group proceeded in moderate-to-high yield. Final deprotec-

tion of compounds 29 and 32 by hydrogenolysis under

3.45 bar (50 psi) H₂in methanol proceeded smoothly to

provide the corresponding products 34 and 36. This stereo-

selective synthesis and new efficient approach, improving

the previously described nonselective ones for accessing

compounds such as 34 and 21, which are precursors to

methyl β--mannopyranoside, is of importance, as such de-

rivatives are of interest for enzyme immunoassays and com-

petitive inhibitor studies.^[37]

Scheme 2. Reagents and conditions: (i) 1. TTBP, BSP, Tf₂O,

CH₂Cl₂, –60 °C, 30 min, 2. MeOH, –60 °C, 2 h, 70%; (ii) 1.

tBuOK, THF, room temp., 5 h, 2. OsO₄, NMO, acetone/water,

room temp., 4 h, 79%.

Synthesis of Mannobiose and Mannotriose

In the present glycosylation study, donor 19 was acti-

vated with Tf₂O in the presence of TTBP and BSP in

CH₂Cl₂at –60 °C to yield α-mannopyranosyl triflate. The

Slightly modified conditions for hydrogenolysis were also

activated species was then treated at –78 °C with various examined and applied for compound 31. Thus, a mixture

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Synthesis of β-(1Ǟ2)-Linked Oligomannosides

Scheme 3. Reagents and conditions: (i) 1. 19, TTBP, BSP, Tf₂O, CH₂Cl₂, –60 °C, 30 min. 2. corresponding acceptor, –78 °C, 3 h, 22

(82%), 23 (85%), 24 (87%), 25 (81%), 26 (72%), 27 (85%), 37 (72%), 38 (74%); (ii) 1. tBuOK, THF, room temp., 2. OsO₄, NMO,

acetone/water, room temp., 28 (80%), 29 (85%), 30 (70%), 31 (85%), 32 (72%), 39 (83%), 40 (81%); (iii) H₂, Pd/C, MeOH, 3.45 bar,

room temp., 33 (93%), 34 (93%), 35 (100%), 36 (94%), 41 (crude yield 96%), 42 (97%).

of solvents (MeOH/EtOAc, 9:1) and lower pressure of Pd/C, EtOH) improved the initial purity of product 33 ob-

2.75 bar (40 psi) H₂for 18.5 h afforded a smooth deprotec- tained and resulted only in either significantly slower or un-

tion as well.

controlled reactions.

Apart from the investigation of the glycosylation selectiv-

A similar iterative protocol, coupling of donor 19 with

ity, a specific objective of the present study was to investi- disaccharide acceptors 28 and 29, afforded protected tri-

gate feasible strategies for the synthesis of β-1,2-manno- saccharides 37 and 38 with 9.5:1 β/α-selectivities in 72 and

biose (33) and β-1,2-mannotriose (41) and to provide their 74% yield, respectively. Repeating the deprotection steps

full characterization by NMR spectroscopy for reference utilized earlier for the corresponding disaccharides (vide su-

purposes. The development of methods for accessing these pra), isomerization of the 2-O-propargyl groups to allenyl,

fully deprotected compounds is motivated by the potential followed by oxidative cleavage and hydrogenolysis of pre-

biological properties of naturally occurring β-1,2-mannans. cursors 39 and 40 under 3.45 bar H₂over Pd/C in methanol

In the first approach, disaccharide 28 was treated under for 21 h/24 h, provided trimers 41 and 42. Also in this case,

similar hydrogenolysis conditions as that employed for 29 the course of hydrogenolysis was similar to that observed

and 32. The benzyl protecting group at the anomeric posi- with the disaccharides, namely, formation of trimeric 41

tion of starting acceptor 11 was selected due to the possibil- along with a small amount of side product. In the trisaccha-

ity of being removed simultaneously with the other protect- ride case, however, no decomposition was observed. LC–

ing groups in a single hydrogenolysis reaction, which would MS analysis of the crude product mixture confirmed the

thus save an extra deprotection step. Exposure of disaccha- presence of, except 41, also cyclohexylmethylene β-1,2--

ride 28 to hydrogenolysis for 19 h gave desired 33 as a 3:1 mannotrioside with m/z = 623 [M + Na]⁺as [M + 96 +

mixture of the α- and β-disaccharides, as verified by ¹H Na]⁺(for 41, m/z = 504 [M]⁺). Pure 41 was gained after

NMR spectroscopy, together with some amount of side chromatographic purification (for details, see the Experi-

products. As a result of decomposition, a small amount mental Section). Formation of the unexpected cyclohex-

(≈5%) of -mannose was detected as well together with an ylmethylene side products in the deprotection steps of both

unexpected product with m/z = 461 [M + Na]⁺as [M + 96 the disaccharide and trisaccharide synthesis was confirmed,

+ Na]⁺(for 33, m/z = 342 [M]⁺), which suggests reduction in addition to mass spectra, by the presence of additional

1

(instead of cleavage) of the anomeric benzyl group to thus high-field H NMR signals (1.1–1.9 ppm) and ¹³C NMR

yield cyclohexylmethylene β-1,2-mannobioside instead of signals (29–39 ppm) consistent with cyclohexyl resonances.

desired 33. A sample of pure 33 was finally obtained by

On the basis of the results above, even larger unprotected

graphite solid-phase extraction (for details, see the Experi- oligosaccharides from β-1,2-mannotetraose onwards should

mental Section). Neither change of solvent to ethanol nor likewise be accessible by utilization of the methodology in-

a modification of the debenzylation protocol (cyclohexene, vestigated here.

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873

M. Poláková, M. U. Roslund, F. S. Ekholm, T. Saloranta, R. Leino

FULL PAPER

Generally, the introduction of nonparticipating groups to lier, by simultaneous removal of all protecting groups in one

the donor molecule, in various combinations, has resulted step, benzyl-protected phosphoramidite was here selected as

in highly stereoselective mannosylations. In the present the starting species for introducing the phosphate group to

study, the use of donor 19 for stereoselective construction the saccharide molecule.

of β-1,2-mannosidic linkages was specifically addressed. In

the coupling reactions of 19 with monosaccharide ac-

ceptors, exclusive β-selectivities were observed. When larger

compounds, in this case trisaccharides, were constructed,

the introduction of the third sugar unit decreased the yield

to 70–75% together with a drop in stereoselectivity to a

β/α ratio of 9.5:1. In light of earlier studies, this is, however,

not unexpected, as similar results are often obtained when

constructing larger oligomannosides. In the previously re-

ported approach to β-1,2-mannooligosaccharides by utiliz-

ing sulfoxide donors (PMB at O-2/Bn at O-3),^[10]similar

Scheme 4. Reagents and conditions: (i) BnBr, NaH, DMF, room

selectivities were recorded: β-only in the disaccharide syn-

thesis and 9.9:1 in the trisaccharide synthesis. The isolated

yields for single synthesis steps were, however, higher than

those gained by the method and reaction scale utilized in

the present study. It is, nevertheless, demonstrated here that

glycoside donor 19, earlier reported to provide highly

stereoselective β-1,3-mannosylations,^[11b]is also well suited

for stereoselective construction of β-1,2-mannosidic link-

ages and in this way serves as another option to access such

compounds. The selectivity obtained by using 19 is in agree-

ment with the earlier reports showing that the size of the

substituent at O-3 of the glycoside donor critically influ-

ences the stereochemical outcome of the reaction. A benzyl

group at O-3 appears to be an ideal choice.^[11c]In this sense,

donor 19 shows enhanced potential for use as a reagent in

β-1,2-mannosylation.

temp., 2 h; (ii) NBS, acetone/water, room temp., 30 min, 62%; (iii)

1. 1H-tetrazole, (OBn)₂PN(iPr)₂, CH₂Cl₂, –40 °C, 1 h 45 min, 2. m-

CPBA, –60 °C, 1 h 15 min, 82%; (iv) H₂, Pd/C, MeOH, 3.45 bar,

room temp., 20 h, 95%.

First, derivative 18 was converted into di-O-benzylated

product 43,^[14b,45]from which the thiophenyl group was re-

leased by treatment with NBS in acetone/water to give 44^[46]

possessing a free anomeric functionality (Scheme 4). Subse-

quent derivatization of 44 with (OBn)₂PN(iPr)₂and 1H-

tetrazole in CH₂Cl₂provided the corresponding phosphite

(quantitative yield, monitored by TLC), which was immedi-

ately converted into phosphate 45 by in situ oxidation with

m-CPBA in one pot. A similar strategy was applied to the

synthesis of phosphate 50 (Scheme 5).

Synthesis of Phosphorylated Mannose and Mannobiose

As a result of the biological importance of glycosyl

1-phosphates, the preparation of similar derivatives of

mannose was also briefly addressed in the present study. In

earlier reports, the analysis of fragments isolated from cell

wall mannan of Candida species (e.g., C. glabrata^[38]and

C. albicans^[39]) has confirmed the presence of β-1,2-linked

mannobiosyl residues esterified with a phosphate group

through C-1 having the α-configuration, as in Man-β-1,2-

– [38]

Man-α-1-HPO₃.

In previous investigations, variously protected^[40]as well

as deprotected^[41]mannopyranosyl-1-phosphate derivatives

were prepared by chemical synthesis. By enzymatic trans-

formations, mannose-6-phosphate was isomerized by phos-

phomannose mutase into mannose-1-phosphate.^[42]The

synthesis of phosphate 50 has not been disclosed earlier. In

Scheme 5. Reagents and conditions: (i) BnBr, NaH, DMF, room

temp., 1.5 h, 96%; (ii) NBS, acetone/water, room temp., 30 min,

62%; (iii) 1. 1H-tetrazole, (OBn)₂PN(iPr)₂, CH₂Cl₂, –40 °C, 1 h

45 min, 2. m-CPBA, –40 °C, 1 h 15 min, 75%; (iv) H₂, Pd/C,

MeOH, 3.45 bar, room temp., 18 h, 70%.

In the corresponding monosaccharide synthesis, the con-

the present study, monosaccharide 18 and disaccharide 30 version of intermediate phosphite to 45 by use of m-CPBA

with a thiophenyl group at the anomeric position were se- (2.5 equiv.) proceeded in quantitative yield. In the case of

lected as precursors for the preparation of phosphorylated disaccharide 49, however, a large excess of the oxidizing

units (Schemes 4 and 5). Various phosphorylation spe- agent (5 equiv. of m-CPBA) was needed to achieve full con-

cies,^[43]including protected phosphoramidites in the pres- version to the phosphate. The two-step phosphorylation

ence of 1H-tetrazole, were used to form phosphites, which protocol proved highly efficient. The isolated yield, how-

were subsequently transformed into phosphates with m- ever, was slightly reduced as a result of repeated purification

CPBA in one pot.^[44]In analogy to the strategy applied ear- (2ϫcolumn chromatography) required to obtain the prod-

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Synthesis of β-(1Ǟ2)-Linked Oligomannosides

uct with high purity for the final deprotection step. Com-

pounds 45 and 49 were both found to exhibit only the α-

configuration at the anomeric center. Next, removal of the

benzyl and benzylidene protecting groups was achieved by

catalytic hydrogenation to provide corresponding phos-

phorylated compounds 46^[47]and 50 in 95 and 70% yield,

respectively. The structures of 46 and 50 were verified by

1

both H and ³¹P NMR spectroscopic analyses. In the ³¹P

NMR spectrum, the phosphorus signals resonate at δ =

–2.48 ppm for 46 and at δ = –2.45 ppm for 50. Also, the

¹H–³¹P HMBC spectrum clearly confirmed the presence of

the phosphate group at the anomeric position.

Scheme 7. Reagents and conditions: (i) 51, TMSOTf (cat.), CH₂Cl₂,

0 °C, 30 min, 78%; (ii) MeONa, MeOH/THF, room temp., 72 h,

98%; (iii) H₂, Pd/C, MeOH, 3.45 bar, room temp., 24 h, 92%.

straightforward. In neither one of the cases was the use of

a catalytic amount of MeONa (0.1 equiv. in MeOH^[19]or

0.1 equiv. in MeOH/THF for 16 h) sufficient for complete

deprotection. Instead, for removal of the 2-O-acetyl group

in disaccharide 53, 1.3 equiv. of MeONa in MeOH/THF

(3:1) for 18 h was required. In the case of trisaccharide 60,

1.6 equiv. of MeONa and a reaction time of 72 h was neces-

sary to ensure quantitative yield.

Modifications to the Oligosaccharide Sugar Units

Preliminary modifications to the oligosaccharide struc-

tures were also carried out by replacing the nonreducing

end mannose unit in the oligomannan structures by -glu-

cose and N-acetyl -glucosamine (GlcNAc), as outlined in

Schemes 6 and 7.

Acceptor 16 was further glycosylated with protected glu-

cosamine 52 to give disaccharide 56 (Scheme 6). Hydrazyn-

olysis of 56 followed by N-acetylation afforded 57, and then

stepwise deprotection finally gave 59 in significantly im-

proved overall yield.^[49]

Conclusions

To summarize, donor 19 was shown to provide enhanced

potential and was successfully applied for the highly stereo-

selective synthesis of various β-1,2-linked mannosides. The

selection of suitably protected building blocks provided ac-

cess to fully deprotected β-1,2-oligomannopyranoses (man-

nobiose and mannotriose). By simple modifications of the

synthesis strategy, mannopyranosyl-α-1-phosphates can be

obtained from similar building blocks as well. Finally, the

synthesis of some modified β-1,2-linked mannoside oligo-

saccharide analogues having single mannose units replaced

by -glucose or GlcNAc was also presented. The full NMR

spectroscopic characterization of the final products as well

as their intermediates is enclosed with this paper (see Ex-

perimental Section), as for many of these compounds com-

plete and fully resolved NMR spectroscopic data was not

disclosed earlier and may be of use as reference data for

other researchers in this field. The biological evaluation of

the compounds prepared for immunostimulatory applica-

tions is currently in progress. Notably, as disclosed by us

elsewhere,^[26]some of the compounds prepared here may

easily be applied as starting materials for further modifica-

tions towards multivalent structures by utilization of homo-

dimerization/ruthenium-catalyzed olefin cross metathesis.

Scheme 6. Reagents and conditions: (i) 51, TMSOTf (cat.), CH₂Cl₂,

0 °C, 30 min, 80%; (ii) MeONa, MeOH/THF, room temp., 18 h,

98%; (iii) H₂, Pd/C, MeOH, 3.45 bar, room temp., 19 h, 93%; (iv)

52, AgOTf, CH₂Cl₂, –20 °C, 1 h, 78%; (v) 1. NH₂NH₂·H₂O, EtOH,

reflux, 15 h, 2. Ac₂O, py, room temp., 16 h, 90%; (vi) tBuOK,

MeOH/THF, 15 h, room temp., 93%; (vii) H₂, Pd/C, MeOH,

3.45 bar, room temp., 6 h, 94%.

A TMSOTf-promoted glycosylation of earlier prepared

acceptors 16 (Scheme 6) and 29 (Scheme 7) with gluco-

pyranosyl trichloroacetimidate 51^[48]gave corresponding

protected di- and trisaccharides 53 and 60 with full β-selec-

tivity, as expected.

Experimental Section

Removal of the acetyl group under Zemplén conditions

Characterization of the Products and General Remarks: Reaction

to obtain desired compounds 54 and 61 was, however, not solvents were dried and distilled prior to use when necessary. All

875

Eur. J. Org. Chem. 2009, 870–888

www.eurjoc.org

M. Poláková, M. U. Roslund, F. S. Ekholm, T. Saloranta, R. Leino

FULL PAPER

reactions containing air- or moisture-sensitive reagents were carried

out under an argon atmosphere.

ZabSpecOaTOF with EI (electron impact) ionization operated in

positive mode. TLC was performed on aluminium sheets precoated

with silica gel 60 F₂₅₄(Merck) and the spots were visualized by

UV and charring with 1.5% (w/v) orcinol monohydrate in H₂SO₄/

MeOH (1:10). Flash column chromatography was carried out with

Silica Gel 60 (0.040–0.600 mm, Merck). Optical rotations were

measured with a Perkin–Elmer 241 polarimeter equipped with a

Na lamp (589 nm) at 23 °C. The LC–ESI-MS/MS analyses were

performed with an Agilent 1100 Series LC/MSD Trap SL instru-

ment (Agilent Technologies) equipped with an electrospray source

and operated in the positive ion mode. HPLC purification was car-

ried out with an Agilent 1100 Series liquid chromatographic sys-

tem.

All NMR spectra were recorded with Bruker Avance spectrometers

1

operating at 500.13 or 600.13 MHz for H, 125.77 or 150.90 MHz

for ¹³C, and 202.47 MHz for ³¹P. All products were fully charac-

1

terized with 1D H, ¹³C, and TOCSY in combination with the 2D

NMR techniques COSY, TOCSY, HSQC, HMSC (heteronuclear

multiple and single bond correlation), and HMBC by using pulse

sequences provided by the instrument manufacturer. The probe

temperature was for most measurements kept at 25 °C. All chemi-

cal shifts are quoted on the δ scale in parts per million (ppm).

Chemical shifts are reported relative to internal Me₄Si in CDCl₃

and CD₃OD (δ_H= 0.0 ppm and δ_C= 0.0 ppm) and HOD for D₂O

(δ_H= 4.79 ppm). ³¹P chemical shifts are externally referenced to a

solution of 0.0485  triphenylphosphate (TPP) in [D₆]acetone (δ_P

= –17.90 ppm). When the signals had very similar chemical shifts,

additional decimals were used to show the order of the signals.

General Procedure for the Preparation of 2 and 3: To a mixture of

1,2,3,4,6-penta-O-acetyl--mannopyranose

(3.0 g,

7.7 mmol,

1 equiv.) and 4 Å molecular sieves (3 g) in CH₂Cl₂(20 mL) under

an argon atmosphere was added the corresponding alcohol

(5 equiv.). The reaction mixture was stirred for 20 min, cooled

down with an ice bath, and BF₃·OEt₂(10 equiv.) was then added

dropwise. The reaction mixture was brought to room temperature

and stirring was continued for 24 h. The reaction mixture was di-

luted with CH₂Cl₂(200 mL) and poured into ice water (200 mL)

with stirring. After 30 min, the phases were separated, and the or-

ganic phase was washed with saturated NaHCO₃(2ϫ100 mL),

water (2ϫ100 mL), and brine (100 mL), dried, and concentrated.

The crude products were purified by column chromatography (hex-

ane/EtOAc, 3:1) to give compounds 2 (3.3 g, 90%) or 3 (2.4 g,

82%), respectively.

In the glycosidation steps, formation of the glycosidic linkage was

confirmed by the heteronuclear one-bond coupling constants^[50]

from the anomeric proton (1-H) to the anomeric carbon atom (C-

1). These coupling constants were measured by using HMBC or

HMSC NMR spectroscopic techniques. A typical one-bond hetero-

nuclear coupling constant for the β-anomer of -mannose was

around 160 Hz, whereas for the α-anomer it was approximately

170 Hz. Also, the characteristic chemical shift for the 5-H proton

and C-5 carbon resonances were used for determining the anomeric

configurations.

The ¹H and ¹³C assignment was based on the ¹H-, ¹³C-, COSY-,

TOCSY-, HSQC-, HMBC-, and HMSC spectra, mainly recorded

with a Bruker Avance 600 MHz spectrometer. The complete com-

putational analysis of the ¹H NMR spectra was achieved by utiliza-

tion of the PERCH NMR software^[51]with the starting values and

spectral parameters obtained from the various NMR techniques

used and briefly described above. The ¹H NMR chemical shifts and

coupling constants were accurately determined for all the described

compounds and the carbon spectrum assignment was based on the

HSQC spectrum. The signals of the anomeric protons are usually

easily identified due to their characteristic chemical shifts between

4.5 and 5.4 ppm and each signal appears as a doublet (d) or as a

Benzyl 2,3,4,6-Tetra-O-acetyl-α-D-mannopyranoside (2): [α]_D=

1

+58.3 (c = 1.0, CHCl₃). H NMR (600.13 MHz, CDCl₃, 25 °C): δ

= 7.35–7.23 (m, 5 H, arom. H), 5.38 (dd, J_3,4= 10.1 Hz, 1 H, 3-

H), 5.30 (dd, J_4,5= 10.2 Hz, 1 H, 4-H), 5.29 (dd, J_2,3= 3.5 Hz, 1

H, 2-H), 4.89 (d, J_1,2= 1.8 Hz, 1 H, 1-H), 4.71 and 4.57 (each d,

J = –11.9 Hz, each 1 H, 1-CH₂Ph), 4.28 (dd, 1 H, 6b-H), 4.04 (dd,

J_6a,6b= –12.3 Hz, 1 H, 6a-H), 4.01 (ddd, J_5,6a= 2.4 Hz, J_5,6b

=

5.1 Hz, 1 H, 5-H), 2.14, 2.12, 2.04, 1.99 (each s, each 3 H,

4ϫCH₃C=O) ppm. ¹³C NMR (150.90 MHz, CDCl₃, 25 °C): δ =

170.6, 170.0, 169.9, 169.8 (4ϫCH₃C=O), 136.2–128.2 (arom. C),

96.8 (C-1), 69.8 (1-CH₂Ph), 69.6 (C-2), 69.2 (C-3), 68.6 (C-5), 66.2

(C-4), 62.4 (C-6), 20.9 (2-CH₃C=O), 20.8 (6-CH₃C=O), 20.7 (3-

and 4-CH₃C=O) ppm. HRMS: calcd. for C₁₇H₂₄O₁₀Na

[M + Na]⁺411.1267; found 411.1262.

3

broad singlet due to the small J_1,2coupling for the β-anomer of

-mannopyranose. All other non-hydroxy sugar protons appear as

doublets of doublets (dd), except 5-H, which has couplings to 4-

H, 6a-H, and 6b-H (ddd), if not additional long-range coupling

constants are visible to exchangeable protons in -NH or -OH or to

another NMR active nucleus such as ³¹P. The coupling constants

are here reported only once for a proton, even though two protons

share the same coupling constant.

Allyl 2,3,4,6-Tetra-O-acetyl-α-

D-mannopyranoside (3): [α]_D= +46.9

(c = 1.0, CHCl₃). ¹H NMR (600.13 MHz, CDCl₃, 25 °C): δ = 5.90

(dddd, J_CH,CH

=

10.4 Hz, J_CH,CH

= 17.2 Hz, 1 H,

2trans

CH₂CH=CH₂),^2c5^is.38 (ddd, J_3,4= 10.1 Hz, J_3,5= –0.58 Hz, 1 H, 3-

H), 5.32 (dddd, J_CH

= –1.4 Hz, 1 H, CH₂CH=CH_2trans),

_2trans,CH_2cis

5.29 (dd, J_4,5= 10.1 Hz, 1 H, 4-H), 5.26 (dd, J_2,3= 3.5 Hz, 1 H, 2-

H), 5.25 (dddd, 1 H, CH₂CH=CH_2cis), 4.29 (dd, 1 H, 6b-H), 4.87

As a result of the small couplings observed for mannose from 1-H

to 2-H (varying between 0.7 Hz to 2 Hz for the two anomers) and

further from 2-H to 3-H (approximately 3.3 Hz), the utilization of

COSY and TOCSY correlation experiments for the well-resolved

anomeric protons was problematic. Accordingly, in some cases it

was easier to use instead the relatively well-separated low-field

chemical shifts of 2-H or the high-field chemical shifts of 5-H, typi-

cal for the β-anomer, for the selective irradiation experiments.

Long-range correlations between the rings as well as the positions

of the different protective groups could then be determined by

HMBC. By use of HMSC, the anomeric configurations could be

(d, J_1,2= 1.8 Hz, 1 H, 1-H), 4.19 (dddd, J_CH

= –12.7 Hz,

= –1.6 Hz, 1

_2a,CH_2b

J_CH

= 5.3 Hz, J_CH

= –1.2 Hz, J_CH

_2a,CH

_2a,CH_{2cis 2a},CH_2trans

H, CH_2aCH=CH), 4.11 (dd, J_6a,6b= –12.2 Hz, 1 H, 6a-H), 4.04

(dddd, J_CH= 6.3 Hz, J_CH= –1.2 Hz, J_CH

=

_2b,CH_2trans

_2b,CH

_2b,CH_2cis

–1.5 Hz, CH_2bCH=CH), 4.02 (dddd, J_5,6a= 2.4 Hz, J_5,6b= 5.3 Hz,

1 H, 5-H), 2.16 (s, 3 H, 2-CH₃C=O), 2.11 (s 3 H, 3-CH₃C=O), 2.04

(s, 3 H, 4-CH₃C=O), 2.00 (s, 3 H, 6-CH₃C=O) ppm. ¹³C NMR

(150.90 MHz, CDCl₃, 25 °C): δ = 170.7, 170.1, 169.9, 169.8

(4ϫCH₃C=O), 132.9 (CH₂CH=CH₂), 118.5 (CH₂CH=CH₂), 96.6

(C-1), 69.7 (C-2), 69.1 (C-3), 68.7 (CH₂CH=CH₂), 68.6 (C-5), 66.2

(C-4), 62.5 (C-6), 20.9, 20.8, 20.7 (4ϫCH₃C=O) ppm. HRMS:

calcd. for C₁₇H₂₄O₁₀Na [M + Na]⁺411.1267; found 411.1262.

1

unambiguously determined on the basis of the size of the J_C,H

coupling constant.

HRMS were recorded using either Bruker Micro Q-TOF with ESI

(electrospray ionization) operated in positive mode or Fison

General Procedure for the Preparation of 4 and 5: To a solution of

acetylated mannopyranoside 2 (3.3 g, 7.5 mmol) or 3 (2.4 g,

876

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Eur. J. Org. Chem. 2009, 870–888

Synthesis of β-(1Ǟ2)-Linked Oligomannosides

6.2 mmol) dissolved in dry MeOH (39 mL) was added 1  NaOMe

(1 mL). The reaction mixture was stirred under an argon atmo-

sphere for 3 h, then neutralized with DOWEX 50 H⁺-form, filtered,

and concentrated. The crude product was purified by column

chromatography (CH₂Cl₂/MeOH, 10:1Ǟ5:1) to give 4 (1.93 g,

95%) or 5 (1.21 g, 89%), respectively.

5.91 (dddd, J_CH,CH

= 10.4 Hz, J_CH,CH

= 17.2 Hz, 1 H,

2trans

CH₂CH=CH₂), 5.3²1^cis(dddd, J_CH

=

–1.6 Hz,

1

H,

_2trans,CH_2cis

CH₂CH=CH_2trans), 5.58 (s

CH₂CH=CH_2cis), 4.93 (d, J_1,2= 1.5 Hz, 1 H, 1-H), 4.28 (dd, J_6a,6b

= –10.3 Hz, 1 H, 6a-H), 4.21 (dddd, J_CH

1

H, CHPh), 5.23 (dddd, 1

= –12.9 Hz, J_CH

_2a,CH_2b

_2a,CH

= 5.2 Hz, J_CH

= –1.3 Hz, J_CH

= –1.7 Hz, 1 H,

_2a,CH_2cis

_2a,CH_2trans

CH_2aCH=CH), 4.12 (dd, J_3,4= 9.7 Hz, 1 H, 3-H), 4.08 (dd, J_2,3

3.5 Hz, 1 H, 2-H), 4.02 (dddd, J_CH= 6.1 Hz, J_CH

=

Benzyl α-D-Mannopyranoside (4) : [α]_D= +85.1 (c = 1.0, MeOH);

ref.^[27a][α]²_D⁶= +74.0 (c = 1.3, H₂O). ¹H NMR (600.13 MHz,

CD₃OD, 25 °C): δ = 7.38–7.26 (m, 5 H, arom. H), 4.75 and 4.52

(each d, J = –11.8 Hz, each 1 H, CH₂Ph), 4.83 (d, J_1,2= 1.7 Hz, 1

_2b,CH

_2b,CH_2cis

–1.2 Hz, J_CH

= –1.5 Hz, CH_2bCH=CH), 3.94 (dd, J_4,5

_2b,CH_2trans

9.4 Hz, 1 H, 4-H), 3.87 (ddd, J_5,6a= 5.0 Hz, J_5,6b= 10.3 Hz, 1 H,

5-H), 3.83 (dd, 1 H, 6b-H) ppm. ¹³C NMR (150.90 MHz, CDCl₃,

25 °C): δ = 137.2–126.2 (arom. C), 133.4 (CH₂CH=CH₂), 117.8

(CH₂CH=CH₂), 102.3 (CHPh), 99.3 (C-1), 78.9 (C-4), 71.0 (C-2),

68.8 (C-6), 68.7 (C-3), 68.3 (CH₂CH=CH₂), 63.1 (C-5) ppm.

HRMS: calcd. for C₁₆H₂₀O₆Na [M + Na]⁺331.1152; found

331.1164.

H, 1-H), 3.84 (dd, J_6a,6b= –11.8 Hz, 1 H, 6a-H), 3.82 (dd, J_2,3

3.4 Hz, 1 H, 2-H), 3.723 (dd, J_3,4= 9.3 Hz, 1 H, 3-H), 3.715 (dd,

1 H, 6b-H), 3.62 (dd, J_4,5= 9.9 Hz, 1 H, 4-H), 3.59 (ddd, J_5,6a

=

2.2 Hz, J_5,6b= 6.0 Hz, 1 H, 5-H) ppm. ¹³C NMR (150.90 MHz,

CD₃OD, 25 °C): δ = 139.1–128.8 (arom. C), 100.7 (C-1), 75.0 (C-

5), 72.7 (C-3), 72.3 (C-2), 69.9 (CH₂Ph), 68.7 (C-4), 63.0 (C-6) ppm.

HRMS: calcd. for C₁₃H₁₈O₆Na [M + Na]⁺293.0996; found

293.0999.

Methyl 4,6-O-Benzylidene-α-D-mannopyranoside (12): [α]_D= +64.7

(c = 1.0, CHCl₃); ref.^[31b][α]²_D³= +70.1 (c = 1.07, CHCl₃). ¹H NMR

(600.13 MHz, CDCl₃, 25 °C): δ = 7.50–7.36 (m, 5 H, arom. H),

5.58 (s, 1 H, CHPh), 4.78 (d, J_1,2= 1.4 Hz, 1 H, 1-H), 4.29 (dd,

Allyl α-

ref.^[32][α]²_D⁶= +51.6 (c = 0.23, H₂O). ¹H NMR (600.13 MHz,

CDCl₃, 25 °C): δ = 5.93 (dddd, J = 10.5 Hz, J_CH,CH

D-Mannopyranoside (5): [α]_D= +73.6 (c = 1.0, MeOH);

J_5,6a= 4.9 Hz, J_6a,6b= –10.3 Hz, 1 H, 6a-H), 4.08 (ddd, J_3,3-OH

=

CH,CH_2cis

2trans

1.4 Hz, J_2,3= 3.7 Hz, J_3,4= 9.6 Hz, 1 H, 3-H), 4.06 (ddd, J_2,2-OH

= 1.1 Hz, 1 H, 2-H), 3.93 (dd, J_4,5= 9.3 Hz, 1 H, 4-H), 3.84 (dd,

J_5,6b= 10.4 Hz, 1 H, 6b-H), 3.82 (ddd, 1 H, 5-H), 3.41 (s 3 H,

OCH₃), 2.59 (d, 1 H, 3-OH), 2.56 (d, 1 H, 2-OH) ppm. ¹³C NMR

(150.90 MHz, CDCl₃, 25 °C): δ = 137.2–126.3 (arom. C), 102.3

(CHPh), 101.2 (C-1), 78.9 (C-4), 70.9 (C-2), 68.9 (C-6), 68.7 (C-3),

62.8 (C-5), 55.1 (OCH₃) ppm.

17.2 Hz, 1 H, CH₂CH=CH₂), 5.29 (dddd, J

= –1.9 Hz,

CH_2trans,CH_2cis

1 H, CH₂CH=CH_2trans), 5.16 (dddd, 1 H, CH₂CH=CH_2cis), 4.79

(dd, J_1,2= 1.7 Hz, J_1,5= –0.61 Hz, 1 H, 1-H), 4.21 (dddd, J

CH_2a,CH_2b

= –13.1 Hz, J_CH

= 5.1 Hz, J_CH

= –1.4 Hz, J_CH

_2a,CH

_2a,CH_{2cis 2a},CH_2trans

= –1.7 Hz, 1 H, CH_2aCH=CH), 4.00 (dddd, J

= 6.0 Hz,

CH_2b,CH

J_CH

= –1.3 Hz, J_CH

= –1.6 Hz, CH_2bCH=CH), 3.83

_2b,CH_2cis

_2b,CH_2trans

(dd, J_6a,6b= –11.8 Hz, 1 H, 6a-H), 3.80 (dd, J_2,3= 3.4 Hz, 1 H, 2-

H), 3.700 (dd, J_3,4= 9.5 Hz, 1 H, 3-H), 3.699 (dd, 1 H, 6b-H), 3.60

General Procedure for the Preparation of Acceptors 14–17: To a

solution containing the corresponding α--mannopyranoside 10–

13 (1 equiv.) in dry toluene (7 mL, 1 mmol) was added Bu₂SnO

(1.02 equiv.). The reaction mixture was stirred under reflux at

120 °C under an argon atmosphere for 3 h, cooled down to room

temperature, followed by the addition of Bu₄NBr (1.06 equiv.), CsF

(1.02 equiv.), and BnBr (1.05 equiv.). The reaction mixture was

stirred at 120 °C for 3 h, cooled down to room temperature, and

diluted with EtOAc (40 mL) and saturated NaHCO₃(30 mL). The

organic phase was separated, and the water phase was extracted

with EtOAc (3ϫ40 mL). The combined organic phase was washed

with water (30 mL) and brine (30 mL), dried, and concentrated.

The crude product was purified by column chromatography (hex-

ane/EtOAc, 4:1) to give 3-O-benzylated products 14 (88%), 15

(88%), 16 (89%), or 17 (84%), respectively.

(dd, J_4,5= 9.9 Hz, 1 H, 4-H), 3.53 (ddd, J_5,6a= 2.3 Hz, J_5,6b

=

6.0 Hz, 1 H, 5-H) ppm. ¹³C NMR (150.90 MHz, CD₃OD, 25 °C):

δ = 135.5 (CH₂CH=CH₂), 117.3 (CH₂CH=CH₂), 100.8 (C-1), 74.8

(C-5), 72.7 (C-3), 72.2 (C-2), 68.9 (CH₂CH=CH₂), 68.7 (C-4), 63.0

(C-6) ppm. HRMS: calcd. for C₉H₁₆O₆Na [M + Na]⁺243.0839;

found 243.0836.

Cyclohexyl 2,3,4,6-Tetra-O-acetyl-α-D-mannopyranoside (8): To a

solution of 1,2,3,4,6-penta-O-acetyl--mannopyranose (2 g,

5.12 mmol, 1 equiv.) and cyclohexanol (0.62 g, 0.64 mL, 1.2 equiv.)

in CH₂Cl₂(30 mL) under an argon atmosphere was added tin(IV)-

chloride (1  in CH₂Cl₂, 0.26 g, 1.05 mL, 1 equiv.). The reaction

mixture was stirred for 16 h, then diluted with CH₂Cl₂(20 mL),

and poured into saturated NaHCO₃solution (50 mL). After being

stirred for 20 min, the organic layer was separated, dried, and con-

centrated. The crude product was further purified by column

chromatography (hexane/EtOAc, 3:1Ǟ2:1) to give 8 (1.41 g, 64%).

Allyl 3-O-Benzyl-4,6-O-benzylidene-α-D-mannopyranoside (15): [α]_D

= +52.8 (c = 1.0, CHCl₃); ref.^[33][α]²_D⁴= +41.0 (c = 5.5, CHCl₃).

¹H NMR (600.13 MHz, CDCl₃, 25 °C): δ = 7.52–7.28 (m, 10 H,

General Procedure for the Preparation of 10–13: The corresponding

α--mannopyranoside 4–6 or 9 (1 equiv.), respectively, was dis-

solved in dry DMF (2.7 mL, 1 mmol) and treated with pTosOH

(0.1 equiv.) and benzaldehyde dimethylacetal (1 equiv.) at room

temperature. The reaction mixture was stirred for 2 h at 60 °C un-

der reduced pressure (200 mbar) by using a rotary evaporator. The

solvent was then evaporated, and the residue was diluted with

EtOAc (100 mL). The organic phase was washed with saturated

NaHCO₃(50 mL), and the water phase was washed with EtOAc

(3ϫ50 mL). The combined organic phase was washed again with

water (2ϫ100 mL), dried, and concentrated. The crude product

was purified by column chromatography (CHCl₃ǞCHCl₃/MeOH,

8:1) to give desired products 10 (50%), 11 (51%), 12 (52%), or 13

(54%), respectively.

arom. H), 5.90 (dddd, J_CH,CH= 10.4 Hz, J_CH,CH

= 17.2 Hz,

1 H, CH₂CH=CH₂), 5.62 (s, 1²H^cis, CHPh), 5.29 (ddd²d^tr,^anJ^s

CH_2trans,CH_2cis

=

–1.6 Hz,

1

H, CH₂CH=CH_2trans), 5.22 (dddd,

1

H,

CH₂CH=CH_2cis), 4.93 (d, J_1,2= 1.5 Hz, 1 H, 1-H), 4.87 and 4.73

(each d, J = –11.8 Hz, each 1 H, CH₂Ph), 4.27 (dd, J_6a,6b

=

–10.5 Hz, 1 H, 6a-H), 4.19 (dddd, J_CH

= –12.9 Hz, J_CH

_2a,CH_2b

_2a,CH

= 5.2 Hz, J_CH

= –1.3 Hz, J_CH

= –1.7 Hz, 1 H,

_2a,CH_2trans

_2a,CH_2cis

CH_2aCH=CH), 4.11 (dd, J_4,5= 9.3 Hz, 1 H, 4-H), 4.09 (ddd, J_2,3

=

3.5 Hz, J_2,2-OH= 1.4 Hz, 1 H, 2-H), 4.00 (dddd, J _,CH= 6.2 Hz,

CH_2b

J_CH

= –1.2 Hz, J_CH

= –1.5 Hz, CH_2bCH=CH), 3.96

_2b,CH_2trans

_2b,CH_2cis

(dd, J_3,4= 9.6 Hz, 1 H, 3-H), 3.87 (ddd, J_5,6a= 5.1 Hz, J_5,6b

=

10.3 Hz, 1 H, 5-H), 3.86 (dd, 1 H, 6b-H) 2.64 (d, 1 H, 2-OH) ppm.

¹³C NMR (150.90 MHz, CDCl₃, 25 °C): δ = 138.0–126.1 (arom.

C), 133.5 (CH₂CH=CH₂), 117.9 (CH₂CH=CH₂), 101.6 (CHPh),

99.1 (C-1), 78.9 (C-4), 75.7 (C-3), 73.1 (CH₂Ph), 70.0 (C-2), 68.9

(C-6), 68.2 (CH₂CH=CH₂), 63.4 (C-5) ppm. HRMS: calcd. for

C₂₃H₂₆O₆[M]⁺398.1729; found 398.1733.

Allyl 4,6-O-Benzylidene-α-D-mannopyranoside (11): [α]_D= +71.4 (c

1

= 1.0, CHCl₃); ref.^[32][α]²_D⁶= +68.6 (c = 0.26, CHCl₃). H NMR

(600.13 MHz, CD₃OD, 25 °C): δ = 7.50–7.37 (m, 5 H, arom. H),

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www.eurjoc.org

877

M. Poláková, M. U. Roslund, F. S. Ekholm, T. Saloranta, R. Leino

FULL PAPER

Methyl 3-O-Benzyl-4,6-O-benzylidene-α-

1

D

-mannopyranoside (16):

[α]²_D⁶= +167.5 (c = 2.0, CHCl₃). H NMR (600.13 MHz, CDCl₃,

[α]_D= +34.2 (c = 0.5, EtOH); ref.^[34][α]²_D⁴= +30.0 (c = 0.4, EtOH).

¹H NMR (600.13 MHz, CDCl₃, 25 °C): δ = 7.50–7.28 (m, 10 H,

arom. H), 5.61 (s, 1 H, CHPh), 4.85 and 4.71 (each d, J = –11.8 Hz,

25 °C): δ = 7.52–7.28 (m, 15 H, arom. H), 5.63 (s, 1 H, CHPh),

5.62 (d, J_1,2= 1.5 Hz, 1 H, 1-H), 4.88 and 4.76 (each d, J =

–12.1 Hz, each 1 H, 3-CH₂Ph), 4.43 (dd, J

= 2.3 Hz,

CH_2a,CH

each 1 H, 3-CH₂Ph), 4.77 (d, J_1,2= 1.4 Hz, 1 H, 1-H), 4.28 (dd, J_CH

= –16.2 Hz, 1 H, CH_2aCϵCH), 4.41 (dd, J

=

_2a,CH_2b

CH_2b,CH

J_6a,6b= –9.9 Hz, 1 H, 6a-H), 4.12 (dd, J_4,5= 9.6 Hz, 1 H, 4-H), 2.4 Hz, 1 H, CH_2bCϵCH), 4.29 (ddd, J_5,6a= 4.8 Hz, J_5,6b

=

4.05 (ddd, J_2,3= 3.3 Hz, J_2,2-OH= 1.2 Hz, 1 H, 2-H), 3.90 (dd, J_3,410.2 Hz, 1 H, 5-H), 4.27 (dd, J_2,3= 3.2 Hz, 1 H, 2-H), 4.23 (dd,

= 9.6 Hz, 1 H, 3-H), 3.86 (dd, 1 H, 6b-H), 3.81 (ddd, J_5,6a= 4.9 Hz, J_4,5= 9.4 Hz, 1 H, 4-H), 4.22 (dd, J_6a,6b= –10.3 Hz, 1 H, 6a-H),

J_5,6b= 10.2 Hz, 1 H, 5-H), 3.38 (s, 3 H, OCH₃) ppm. 2.65 (d, 1 H, 4.00 (dd, J_3,4= 10.0 Hz, 1 H, 3-H), 3.87 (dd, 1 H, 6b-H), 2.44 (dd,

2-OH). ¹³C NMR (150.90 MHz, CDCl₃, 25 °C): δ = 138.1–125.8

(arom. C), 101.2 (CHPh), 100.5 (C-1), 78.4 (C-4), 75.2 (C-3), 72.5

(3-CH₂Ph), 69.4 (C-2), 68.6 (C-6), 62.6 (C-5), 54.7 (OCH₃) ppm.

1 H, CH₂CϵCH) ppm. ¹³C NMR (150.90 MHz, CDCl₃, 25 °C): δ

=

138.2–126.1 (arom. C), 101.5 (CHPh), 87.4 (C-1), 79.5

(CH₂CϵCH), 79.4 (C-4), 77.7 (C-2), 76.1 (C-3), 75.2 (CH₂CϵCH),

73.3 (3-CH₂Ph), 68.5 (C-6), 65.3 (C-5), 58.8 (CH₂CϵCH) ppm.

Methyl 3-O-Benzyl-4,6-O-benzylidene-2-O-(prop-2-ynyl)-β-D-man-

nopyranoside (20): Donor 19 (0.31 g, 0.63 mmol, 1 equiv.), TTBP

(0.24 g, 0.95 mmol, 1.5 equiv.), 4 Å molecular sieves (0.5 g) were

stirred in dry CH₂Cl₂(6 mL) under an argon atmosphere. The tem-

perature was reduced to –40 °C. 1-Benzenesulfinylpiperidine (BSP;

0.16 g, 0.76 mmol, 1.2 equiv.) was then added, and the temperature

was lowered to –60 °C. Tf₂O (0.23 g, 0.14 mL, 0.82 mmol,

1.3 equiv.) was added into the solution followed by the addition

of dry MeOH (61 mg, 77 µL, 1.9 mmol, 3 equiv.) after stirring for

20 min. The reaction mixture was stirred for 2 h at –60 °C, then

warmed up to room temperature and diluted with CH₂Cl₂(40 mL).

The organic phase was washed with saturated NaHCO₃

(2ϫ20 mL) and water (20 mL), dried, and concentrated. Purifica-

tion by column chromatography (hexane/EtOAc, 8:1Ǟ5:1) af-

forded the title compound (0.18 g, 70%). [α]_D= –80.0 (c = 1.0,

CH₂Cl₂). ¹H NMR (600.13 MHz, CDCl₃, 25 °C): δ = 7.51–7.27 (m,

10 H, arom. H), 5.60 (s, 1 H, CHPh), 4.84 and 4.81 (each d, J =

General Procedure for the Coupling Reaction: To donor 19 (1 equiv.)

in dry CH₂Cl₂(4 mL/0.5 mmol of donor) under an argon atmo-

sphere was added TTBP (1.5 equiv.) and 4 Å molecular sieves, and

the temperature was reduced to –40 °C. BSP (1.2 equiv.) was then

added, and the temperature was brought to –60 °C. The mixture

was stirred for 10 min, and Tf₂O (1.3 equiv.) was added into solu-

tion; stirring was continued for 30 min. The temperature was re-

duced to –78 °C, and the acceptor (1.15 equiv.) in dry CH₂Cl₂

(2.4 mL/0.056 mmol of acceptor) was added dropwise over a period

of 15 min. Stirring was continued for 2 h at –78 °C, and the reac-

tion was quenched by the addition of (EtO)₃P (3 equiv.) at the same

temperature. Stirring was continued for an additional 1 h at –78 °C,

and the reaction mixture was then brought to room temperature.

The reaction mixture was diluted with CH₂Cl₂(20 mL), and the

molecular sieves were filtered off. The organic phase was washed

with saturated NaHCO₃(3ϫ20 mL), brine (20 mL), and water

(20 mL), dried, and concentrated. Column chromatography (hex-

ane/EtOAc, 8:1Ǟ4:1) gave the desired disaccharides or trisaccha-

rides, respectively.

–12.5 Hz, each 1 H, 3-CH₂Ph), 4.60 (dd, J

= 2.4 Hz,

CH_2a,CH

J_CH

= –16.1 Hz, 1 H, CH_2aCϵCH), 4.56 (dd, J

=

_2a,CH_2b

CH_2b,CH

2.4 Hz, 1 H, CH_2bCϵCH), 4.40 (d, J_1,2= 0.95 Hz, 1 H, 1-H), 4.32

(dd, J_6a,6b= –10.4 Hz, 1 H, 6a-H), 4.18 (dd, J_2,3= 3.1 Hz, 1 H, 2-

H), 4.12 (dd, J_4,5= 9.3 Hz, 1 H, 4-H), 3.91 (dd, 1 H, 6b-H), 3.63

(dd, J_3,4= 9.9 Hz, 1 H, 3-H), 3.52 (s, 3 H, OCH₃), 3.32 (ddd, J_5,6a

= 4.9 Hz, J_5,6b= 10.1 Hz, 1 H, 5-H), 2.48 (dd, 1 H, CH₂CϵCH)

ppm. ¹³C NMR (150.90 MHz, CDCl₃, 25 °C): δ = 138.2–126.2

(arom. C), 102.9 (C-1), 101.4 (CHPh), 80.2 (CH₂CϵCH), 78.5 (C-

4), 77.0 (C-3), 75.1 (C-2), 74.9 (CH₂CϵCH), 72.5 (3-CH₂Ph), 68.6

(C-6), 67.5 (C-5), 60.0 (CH₂CϵCH), 57.5 (OCH₃) ppm. HRMS:

calcd. for C₂₄H₂₆O₆[M]⁺410.1729; found 410.1728.

General Procedure for Propargyl Deprotection

Step 1: To a solution of the corresponding 2-O-propargylated com-

pound (22, 24, 25, 26, 27, 37, or 38, respectively) dissolved in dry

THF (1 mL, 50 mg of compound) was added tBuOK (1.2 equiv.).

The mixture was stirred at room temperature and then diluted with

CH₂Cl₂(20 mL), and washed with water (2ϫ10 mL). The organic

phase was dried and concentrated. Products were analyzed by

NMR spectroscopy and directly used in the next step.

Step 2: The isomerized 2-O-allenyl sugar (1 equiv.) was dissolved

in acetone/water (4:1, 3 mL) and treated with OsO₄(1.1 equiv.) fol-

lowed by NMO (2 equiv.). The mixture was stirred at room tem-

perature. The solvent was evaporated, and the residue was dissolved

in CH₂Cl₂(20 mL). The organic phase was washed with brine

(10 mL) and brine washed with CH₂Cl₂(10 mL). The combined

organic phase was again washed with brine (2ϫ10 mL) and water

(10 mL), dried, and concentrated. The residue was purified by col-

umn chromatography (hexane/EtOAc, 3:1Ǟ2.5:1) to give the 2-O-

deprotected product.

Methyl 3-O-Benzyl-4,6-O-benzylidene-β-D-mannopyranoside (21):

Compound 20 (0.18 g, 0.44 mmol) was dissolved in dry THF

(5 mL) and treated with tBuOK (52 mg, 0.47 mmol, 1.2 equiv.). Af-

ter being stirred for 5 h, the mixture was diluted with CH₂Cl₂

(30 mL) and washed with water (2ϫ15 mL). The organic phase

was dried and concentrated to give the isomerized product (2-O-

allenyl ether), which was analyzed by NMR spectroscopy and used

directly in the next step. 2-O-Allenyl ether (0.18 g, 0.044 mmol) was

dissolved in acetone/water (4:1, 5 mL) and treated with OsO₄

(13 mg, 0.052 mmol, 0.12 equiv.) and NMO (0.10 g, 0.87 mmol,

2 equiv.). The mixture was stirred for 4 h at room temperature. The

solvent was evaporated, and the residue was dissolved in CH₂Cl₂

(20 mL). The organic phase was washed with brine (20 mL) and

brine washed with dichloromethane (20 mL). The combined or-

ganic phase was again washed with brine (2ϫ10 mL) and water

(20 mL), dried, and concentrated. The residue was purified by col-

umn chromatography (hexane/EtOAc, 2:1Ǟ1.5:1), and desired

product 21 was obtained (0.13 g, 79%). Analytical data for com-

pound 21 are in excellent agreement with those previously report-

ed.^[35a]

Benzyl 3-O-Benzyl-4,6-O-benzylidene-2-O-(prop-2-ynyl)-β-

D-man-

nopyranosyl-(1Ǟ2)-3-O-benzyl-4,6-O-benzylidene-α- -mannopyr-

D

anoside (22): The coupling reaction was carried out starting from

donor 19 (0.32 g, 0.66 mmol). Yield: 0.44 g (82%). [α]_D= –37.0 (c

1

= 1.0, CH₂Cl₂). H NMR (600.13 MHz, CDCl₃, 25 °C): δ = 7.51–

7.28 (m, 25 H, arom. H), 5.60 (s, 1 H, CHPh), 5.57 (s, 1 H, CHЈPh),

4.96 (d, J_1,2= 1.6 Hz, 1 H, 1-H), 4.80 (s, 2 H, 3Ј-CH₂Ph), 4.73 and

4.50 (each d, J = –11.9 Hz, each 1 H, 1-CH₂Ph), 4.72 (s, 2 H, 3-

CH₂Ph), 4.70 (dd, J

= 2.4 Hz, J_CH

= –16.1 Hz, 1 H,

CH_2a,CH

_2a,CH_2b

CH_2aCϵCH), 4.63 (d, J_1Ј,2Ј= 0.84 Hz, 1 H, 1Ј-H), 4.61 (dd,

J_CH_,CH= 2.4 Hz, 1 H, CH_2bCϵCH), 4.27 (dd, J_2,3= 3.4 Hz, 1 H,

Phenyl 3-O-Benzyl-4,6-O-benzylidene-2-O-(prop-2-ynyl)-1-thio-α-

D-

mannopyranoside (19): [α]_D= +143.9 (c = 1.0, CHCl₃); ref.^[11b]

2-H²)^b, 4.239 (dd, J_6Јa,6Јb= –10.4 Hz, 1 H, 6Јa-H), 4.239 (dd, J_2Ј,3Ј

=

878

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Eur. J. Org. Chem. 2009, 870–888

Synthesis of β-(1Ǟ2)-Linked Oligomannosides

3.1 Hz, 1 H, 2Ј-H), 4.231 (dd, J_6a,6b= –10.2 Hz, 1 H, 6a-H), 4.16 1 H, 5Ј-H), 2.51 (dd, 1 H, CH₂CϵCH) ppm. ^{1 3}C NMR

(dd, J_4Ј,5Ј= 9.4 Hz, 1 H, 4Ј-H), 4.12 (dd, J_4,5= 9.5 Hz, 1 H, 4-H),

(150.90 MHz, CDCl₃, 25 °C): δ = 138.7–126.0 (arom. C), 101.6

4.02 (dd, J_3,4= 10.0 Hz, 1 H, 3-H), 3.87 (ddd, J_5,6a= 4.9 Hz, J_5,6b(CЈHPh), 101.4 (CHPh), 100.3 (C-1Ј), 99.2 (C-1), 80.4

= 10.4 Hz, 1 H, 5-H), 3.84 (dd, 1 H, 6Јb-H), 3.82 (dd, 1 H, 6b-H),

3.60 (dd, J_3Ј,4Ј= 9.9 Hz, 1 H, 3Ј-H), 3.26 (ddd, J_5Ј,6Јa= 4.8 Hz,

(CH₂CϵCH), 78.5 (C-4), 78.3 (C-4Ј), 77.0 (C-3Ј), 75.0

(CH₂CϵCH), 74.6 (C-2Ј), 74.3 (C-2), 74.1 (C-3), 72.2 (3Ј-CH₂Ph),

J_5Ј,6Јb= 10.1 Hz, 1 H, 5Ј-H), 2.44 (dd, 1 H, CH₂CϵCH) ppm. ¹³C 71.5 (3-CH₂Ph), 68.9 (C-6Ј), 68.5 (C-6), 67.8 (C-5Ј), 64.0 (C-5),

NMR (150.90 MHz, CDCl₃, 25 °C): δ = 138.7–126.0 (arom. C),

59.8 (CH₂CϵCH), 54.9 (OCH₃) ppm. HRMS: calcd. for

101.6 (CHPh), 101.4 (CЈHPh), 100.2 (C-1Ј), 97.3 (C-1), 80.4 C₄₄H₄₆O₁₁[M]⁺750.3040; found 750.3056.

(CH₂CϵCH), 78.6 (C-4), 78.3 (C-4Ј), 76.9 (C-3Ј), 75.0

Cyclohexyl 3-O-Benzyl-4,6-O-benzylidene-2-O-(prop-2-ynyl)-β-D-

(CH₂CϵCH), 74.5 (C-2Ј), 74.4 (C-2), 74.4 (C-3), 72.2 (3Ј-CH₂Ph),

71.7 (3-CH₂Ph), 69.4 (1-CH₂Ph(, 68.9 (C-6), 68.5 (C-6Ј), 67.8 (C-

5Ј), 64.4 (C-5), 59.8 (CH₂CϵCH) ppm. HRMS: calcd. for

C₅₀H₅₀O₁₁[M]⁺826.3353; found 826.3325.

mannopyrano-syl-(1Ǟ2)-3-O-benzyl-4,6-O-benzylidene-α-

pyranoside (25): The coupling reaction was carried out by starting

from donor 19 (90 mg, 0.18 mmol). Yield: 0.12 g (81 %). [α]_D

D-manno-

=

1

–39.0 (c = 1.0, CH₂Cl₂). H NMR (600.13 MHz, CDCl₃, 25 °C): δ

= 7.50–7.25 (m, 20 H, arom. H), 5.60 (s, 1 H, CHPh), 5.58 (s, 1 H,

CHЈPh), 5.00 (d, J_1,2= 1.7 Hz, 1 H, 1-H), 4.82 (s, 2 H, 3Ј-CH₂Ph),

Allyl 3-O-Benzyl-4,6-O-benzylidene-2-O-(prop-2-ynyl)-β-

D-manno-

pyranosyl-(1Ǟ2)-3-O-benzyl-4,6-O-benzylidene-α- -mannopyrano-

D

side (23): The coupling reaction was carried out by starting from

donor 19 (0.16 g, 0.33 mmol). Yield: 0.22 g (85%). [α]_D= –49.0 (c

4.73 (s, 2 H, 3-CH₂Ph), 4.72 (dd, J

= 2.3 Hz, J_CH

=

CH_2a,CH

_2a,CH_2b

–16.1 Hz, 1 H, CH_2aCϵCH), 4.68 (d, J_1Ј,2Ј= 0.73 Hz, 1 H, 1Ј-H),

4.62 (dd, J_CH_,CH= 2.4 Hz, 1 H, CH_2bCϵCH), 4.27 (dd, J_6Јa,6Јb

1

= 1.0, CH₂Cl₂). H NMR (600.13 MHz, CDCl₃, 25 °C): δ = 7.52–

=

2b

7.26 (m, 20 H, arom. H), 5.89 (dddd, J_CH,CH= 10.4, J_CH,CH

–10.4 Hz, 1 H, 6Јa-H), 4.26 (dd, J_2Ј,3Ј= 3.1 Hz, 1 H, 2Ј-H), 4.24

(dd, J_6a,6b= –10.2 Hz, 1 H, 6a-H), 4.18 (dd, J_2,3= 3.3 Hz, 1 H, 2-

H), 4.17 (dd, J_4Ј,5Ј= 9.3 Hz, 1 H, 4Ј-H), 4.10 (dd, J_4,5= 9.5 Hz, 1

= 17.2 Hz, 1 H, CH₂CH=CH₂), 5.60 (s, 1 H, ²C^cisHPh), 5.59 (s, 1^2tH^ran,^s

C H Ј P h ) , 5 . 2 7 ( d d d d , J _{C H}

= – 1 . 6 H z , 1 H ,

_{2 t r a n s}, C H _{2 c i s}

CH₂CH=CH_2trans), 5.22 (dddd, 1 H, CH₂CH=CH_2cis), 4.91 (d, J_1,2

= 1.6 Hz, 1 H, 1-H), 4.82 (s, 2 H, 3Ј-CH₂Ph), 4.74 and 4.712 (each

H, 4-H), 3.99 (dd, J_3,4= 10.0 Hz, 1 H, 3-H), 3.89 (ddd, J_5,6a

=

4.7 Hz, J_5,6b= 10.4 Hz, 1 H, 5-H), 3.86 (dd, 1 H, 6Јb-H), 3.80 (dd,

1 H, 6b-H), 3.63 (dd, J_3Ј,4Ј= 9.9 Hz, 1 H, 3Ј-H), 3.58 (m, 1 H,

OCHC₅H₁₀), 3.32 (ddd, J_5Ј,6Јa= 4.8 Hz, J_5Ј,6Јb= 10.0 Hz, 1 H, 5Ј-

H), 2.50 (dd, 1 H, CH₂CϵCH), 1.86–1.18 (m, 10 H, OCHC₅H₁₀)

ppm. ¹³C NMR (150.90 MHz, CDCl₃, 25 °C): δ = 138.9–125.9

(arom. C), 101.5 (CHPh), 101.4 (CЈHPh), 100.4 (C-1Ј), 96.1 (C-1),

81.0 (CH₂CϵCH), 79.0 (C-4), 78.2 (C-2), 76.9 (C-3Ј), 75.7

(OCHC₅H₁₀), 75.4 (C-2Ј), 75.0 (CH₂CϵCH), 74.8 (C-4Ј), 74.5 (C-

3), 72.2 (3-CH₂Ph), 71.6 (3Ј-CH₂Ph), 69.0 (C-6Ј), 68.7 (C-6), 67.8

(C-5Ј), 64.3 (C-5), 59.8 (CH₂CϵCH), 33.3, 31.3, 25.6, 23.8, 23.5

(OCHC₅H₁₀) ppm. HRMS: calcd. for C₄₉H₅₄O₁₁[M]⁺818.3666;

found 818.3730.

d, J = –12.1 Hz, each 1 H, 3-CH₂Ph), 4.713 (dd, J

_,CH= 2.4 Hz,

CH_2a

J_CH

= –16.2 Hz, 1 H, CH_2aCϵCH), 4.67 (d, J_1Ј,2Ј= 0.44 Hz,

_2a,CH_2b

1 H, 1Ј-H), 4.62 (dd, J_CH

= 2.4 Hz, 1 H, CH_2bCϵCH), 4.28

_2b,CH

(dd, J_6Јa,6ЈbЈ= –10.4 Hz, 1 H, 6Јa-H), 4.27 (dd, J_2,3= 3.4 Hz, 1 H,

2-H), 4.26 (dd, J_2Ј,3Ј= 3.2 Hz, 1 H, 2Ј-H), 4.25 (dd, J_6a,6b

=

–10.1 Hz, 1 H, 6a-H), 4.19 (dddd, J_CH

= –13.0 Hz, J_CH

_2a,CH_2b

_2a,CH

= 5.1 Hz, J_CH

= –1.4 Hz, J_CH

= –1.7 Hz, 1 H,

_2a,CH_2trans

_2a,CH_2cis

CH_2aCH=CH₂), 4.18 (dd, J_4Ј,5Ј= 9.3 Hz, 1 H, 4Ј-H), 4.10 (dd, J_4,5

= 9.2 Hz, 1 H, 4-H), 3.983 (dd, J_3,4= 10.0 Hz, 1 H, 3-H), 3.977

(dddd, J_CH

= 6.2 Hz, J_CH

= –1.2 Hz, J_CH

=

_2b,CH

_2b,CH_2cis

_2b,CH_2trans

–1.6 Hz, 1 H, CH_2bCH=CH₂), 3.86 (dd, 1 H, 6Јb-H), 3.83 (ddd,

J_5,6a= 4.8 Hz, J_5,6b= 10.4 Hz, 1 H, 5-H), 3.81 (dd, 1 H, 6b-H),

3.63 (dd, J_3Ј,4Ј= 9.9 Hz, 1 H, 3Ј-H), 3.31 (ddd, J_5Ј,6Јa= 4.8 Hz,

J_5Ј,6Јb= 10.1 Hz, 1 H, 5Ј-H), 2.50 (dd, 1 H, CH₂CϵCH) ppm. ¹³C

NMR (150.90 MHz, CDCl₃, 25 °C): δ = 138.7–126.0 (arom. C),

133.3 (CH₂CH=CH₂), 117.8 (CH₂CH=CH₂), 101.6 (CHPh), 101.4

(CЈHPh), 100.3 (C-1Ј), 97.3 (C-1), 80.4 (CH₂CϵCH), 78.5 (C-4),

78.3 (C-4Ј), 76.9 (C-3Ј), 75.0 (CH₂CϵCH), 74.5 (C-2Ј), 74.30 (C-

2), 74.26 (C-3), 72.2 (3Ј-CH₂Ph), 71.5 (3-CH₂Ph), 68.8 (C-6), 68.5

(C-6Ј), 68.2 (CH₂CH=CH₂), 67.8 (C-5Ј), 64.2 (C-5), 59.8

(CH₂CϵCH) ppm. HRMS: calcd. for C₄₆H₄₈O₁₁[M]⁺776.3197;

found 776.3217.

Phenyl 3-O-Benzyl-4,6-O-benzylidene-2-O-(prop-2-ynyl)-β-

nopyranosyl-(1Ǟ2)-3-O-benzyl-4,6-O-benzylidene-1-thio-α-

nopyranoside (26): The coupling reaction was carried out by start-

ing from donor 19 (0.23 g, 0.48 mmol). Yield: 0.28 g (72%). [α]_D

D

-man-

D-man-

=

1

+9.0 (c = 1.0, CH₂Cl₂). H NMR (600.13 MHz, CDCl₃, 25 °C): δ

= 7.57–7.28 (m, 25 H, arom. H), 5.61 (s, 1 H, CHPh), 5.58 (s, 1 H,

CHЈPh), 5.54 (d, J_1,2= 1.5 Hz, 1 H, 1-H), 4.80 (s, 2 H, 3Ј-CH₂Ph),

4.76 and 4.73 (each d, J = –12.0 Hz, each 1 H, 3-CH₂Ph), 4.71 (dd,

J_CH

= 2.4 Hz, J_CH

= –16.2 Hz, 1 H, CH_2aCϵCH), 4.66

_2a,CH

_2a,CH_2b

(d, J_1Ј,2Ј= 0.84 Hz, 1 H, 1Ј-H), 4.61 (dd, J_CH

= 2.4 Hz, 1 H,

_2b,CH

CH_2bCϵCH), 4.50 (dd, J_2,3= 3.3 Hz, 1 H, 2-H), 4.32 (ddd, J_5,6a

4.8 Hz, J_5,6b= 10.2 Hz, 1 H, 5-H), 4.26 (dd, J_6Јa,6Јb= –10.3 Hz, 1

H, 6Јa-H), 4.25 (dd, J_2Ј,3Ј= 3.1 Hz, 1 H, 2Ј-H), 4.23 (dd, J_6a,6b

=

Methyl 3-O-Benzyl-4,6-O-benzylidene-2-O-(prop-2-ynyl)-β-

D-man-

nopyranosyl-(1Ǟ2)-3-O-benzyl-4,6-O-benzylidene-α- -mannopyr-

D

=

anoside (24): The coupling reaction was carried out as outlined in

the general procedure by starting from donor 19 (0.27 g,

0.55 mmol). Yield: 0.35 g (87%). [α]_D= –56.5 (c = 1.0, CH₂Cl₂).

¹H NMR (600.13 MHz, CDCl₃, 25 °C): δ = 7.50–7.23 (m, 20 H,

arom. H), 5.60 (s, 1 H, CHЈPh), 5.59 (s, 1 H, CHPh), 4.82 (s, 2 H,

3Ј-CH₂Ph), 4.76 (d, J_1,2= 1.6 Hz, 1 H, 1-H), 4.73 and 4.70 (each

–10.2 Hz, 1 H, 6a-H), 4.18 (dd, J_4,5= 9.5 Hz, 1 H, 4-H), 4.17 (dd,

J_4Ј,5Ј= 9.3 Hz, 1 H, 4Ј-H), 3.96 (dd, J_3,4= 10.0 Hz, 1 H, 3-H), 3.85

(dd, 1 H, 6Јb-H), 3.84 (dd, 1 H, 6b-H), 3.62 (dd, J_3Ј,4Ј= 9.9 Hz, 1

H, 3Ј-H), 3.30 (dd, J_5Ј,6Јa= 4.8 Hz, J_5Ј,6Јb= 10.1 Hz, 1 H, 5Ј-H),

2.46 (dd, 1 H, CH₂CϵCH) ppm. ¹³C NMR (150 MHz, CDCl₃,

25 °C): δ = 137.4–126.0 (arom. C), 102.0 (CHPh), 101.8 (CЈHPh),

99.3 (C-1Ј), 86.0 (C-1), 80.3 (CH₂CϵCH), 78.5 (C-4), 78.2 (C-4Ј),

76.9 (C-3Ј), 75.4 (CH₂CϵCH), 75.1 (C-2Ј), 74.5 (C-2), 74.2 (C-3),

72.1 (3Ј-CH₂Ph), 71.4 (3-CH₂Ph), 68.5, 68.4 (C-6, C-6Ј), 67.7 (C-

5Ј), 65.4 (C-5), 59.7 (CH₂CϵCH) ppm. HRMS: calcd. for

C₄₉H₄₉O₁₀S [M + H]⁺829.3046; found 829.3103.

d, J = –12.1 Hz, each 1 H, 3-CH₂Ph), 4.72 (dd, J

_,CH= 2.4 Hz,

CH_2a

J_CH

= –16.2 Hz, 1 H, CH_2aCϵCH), 4.68 (dd, J_1Ј,2Ј= 0.92 Hz,

_2a,CH_2b

1 H, 1Ј-H) 4.63 (dd, J_CH

= 2.4 Hz, 1 H, CH_2bCϵCH), 4.28

_2b,CH

(dd, J_6Јa,6Јb= –10.3 Hz, 1 H, 6Јa-H), 4.27 (dd, J_2Ј,3Ј= 3.1 Hz, 1 H,

2Ј-H), 4.26 (dd, J_6a,6b= –10.3 Hz, 1 H, 6a-H), 4.23 (dd, J_2,3

=

3.4 Hz, 1 H, 2-H), 4.18 (dd, J_4Ј,5Ј= 9.3 Hz, 1 H, 4Ј-H), 4.09 (dd,

J_4,5= 9.4 Hz, 1 H, 4-H), 3.93 (dd, J_3,4= 10.0 Hz, 1 H, 3-H), 3.87

(dd, 1 H, 6Јb-H), 3.82 (dd, 1 H, 6b-H), 3.78 (ddd, J_5,6a= 4.7 Hz,

J_5,6b= 10.4 Hz, 1 H, 5-H), 3.63 (dd, J_3Ј,4Ј= 9.9 Hz, 1 H, 3Ј-H),

Methyl 3-O-Benzyl-4,6-O-benzylidene-2-O-(prop-2-ynyl)-β-

nopyranosyl-(1Ǟ2)-3-O-benzyl-4,6-O-benzylidene-β- -mannopyr-

anoside (27): The coupling reaction was carried out by starting

D-man-

D

3.37 (s, 3 H, OCH₃), 3.32 (ddd, J_5Ј,6Јa= 4.9 Hz, J_5Ј,6Јb= 10.1 Hz, from donor 19 (0.11 g, 0.23 mmol). Yield: 0.17 g (85 %). [α]_D

=

Eur. J. Org. Chem. 2009, 870–888

www.eurjoc.org

879

M. Poláková, M. U. Roslund, F. S. Ekholm, T. Saloranta, R. Leino

FULL PAPER

1

–122.5 (c = 1.0, CH₂Cl₂). H NMR (600.13 MHz, CDCl₃, 25 °C): J_5Ј,6Јb= 10.1 Hz, 1 H, 5Ј-H), 3.36 (s, 3 H, OCH₃), 3.17 (d, 1 H, 2Ј-

δ = 7.50–7.24 (m, 20 H, arom. H), 5.59 (s, 1 H, CHPh), 5.57 (s, 1 OH) ppm. ¹³C NMR (150.90 MHz, CDCl₃, 25 °C): δ = 138.3–126.0

H, CHЈPh), 4.85 (d, J_1Ј,2Ј= 0.86 Hz, 1 H, 1Ј-H), 4.84 and 4.82

(each d, J = –12.9 Hz, each 1 H, 3Ј-CH₂Ph), 4.76 and 4.72 (each

(arom. C), 101.5 (CHPh), 101.4 (CЈHPh), 99.6 (C-1), 98.2 (C-1Ј),

78.6 (C-4), 78.5 (C-4Ј), 76.3 (C-3Ј), 74.3 (C-3), 72.9 (C-2), 72.4 (3-

CH₂Ph), 72.3 (3Ј-CH₂Ph), 69.6 (C-2Ј), 68.7 (C-6), 68.7 (C-6Ј), 67.0

(C-5Ј), 63.8 (C-5), 54.9 (OCH₃) ppm. HRMS: calcd. for C₄₁H₄₄O₁₁

[M]⁺712.2884; found 712.2885.

d, J = –12.3 Hz, each 1 H, CH₂Ph), 4.72 (dd, J

= 2.3 Hz,

CH_2a,CH

J_CH

= –16.0 Hz, 1 H, CH_2aCϵCH), 4.62 (dd, J

=

_2a,CH_2b

CH_2b,CH

2.4 Hz, 1 H, CH_2bCϵCH), 4.38 (d, J_1,2= 0.76 Hz, 1 H, 1-H), 4.34

(dd, J_6a,6b= –10.4 Hz, 1 H, 6a-H), 4.33 (dd, J_2Ј,3Ј= 3.3 Hz, 1 H,

Phenyl 3-O-Benzyl-4,6-O-benzylidene-β-

D

-mannopyranosyl-(1Ǟ2)-

2Ј-H), 4.30 (dd, J_6Јa,6Јb= –10.4 Hz, 1 H, 6Јa-H), 4.28 (dd, J_2,3

=

3-O-benzyl-4,6-O-benzylidene-1-thio-α-

D

-manno-pyranoside (30):

3.3 Hz, 1 H, 2-H), 4.17 (dd, J_4Ј,5Ј= 9.3 Hz, 1 H, 4Ј-H), 4.04 (dd,

J_4,5= 9.3 Hz, 1 H, 4-H), 3.89 (dd, 1 H, 6Јb-H), 3.84 (dd, 1 H, 6b-

H), 3.62 (dd, J_3,4= 9.9 Hz, 1 H, 3-H), 3.61 (dd, J_3Ј,4Ј= 9.9 Hz, 1

The propargyl deprotection was carried out by starting from disac-

charide 26 (0.25 g, 0.30 mmol). Reaction time for 1st step 5 h, for

2nd step 2.5 h. Yield: 0.16 g (70%). [α]_D= +11.0 (c = 1.0, CH₂Cl₂).

¹H NMR (600.13 MHz, CDCl₃, 25 °C): δ = 7.51–7.26 (m, 25 H,

arom. H), 5.54 (s, 1 H, CHPh), 5.49 (d, J_1,2= 1.4 Hz, 1 H, 1-H),

5.46 (s, 1 H, CHЈPh), 4.84 and 4.76 (each d, J = –12.2 Hz, each 1

H, 3-CH₂Ph), 4.81 and 4.78 (each d, J = –11.8 Hz, each 1 H, 3Ј-

CH₂Ph), 4.73 (d, J_1Ј,2Ј= 1.3 Hz, 1 H, 1Ј-H), 4.61 (dd, J_2,3= 3.4 Hz,

1 H, 2-H), 4.283 (dd, J_4Ј,5Ј= 9.5 Hz, 1 H, 4Ј-H), 4.281 (ddd, J_5,6a

= 4.8 Hz, J_5,6b= 10.2 Hz, 1 H, 5-H), 4.25 (dd, J_6Јa,6Јb= –10.3 Hz,

1 H, 6Јa-H), 4.194 (dd, J_6a,6b= –10.3 Hz, 1 H, 6a-H), 4.188 (dd,

J_4,5= 9.5 Hz, 1 H, 4-H), 4.15 (dd, J_2Ј,3Ј= 3.9 Hz, 1 H, 2Ј-H), 3.98

(dd, J_3,4= 9.9 Hz, 1 H, 3-H), 3.77 (dd, 1 H, 6b-H), 3.74 (dd, 1 H,

H, 3Ј-H), 3.50 (s, 3 H, OCH₃), 3.34 (ddd, J_5,6a= 4.8 Hz, J_5,6b

=

10.1 Hz, 1 H, 5-H), 3.33 (ddd, J_5Ј,6Јa= 4.8 Hz, J_5Ј,6Јb= 10.1 Hz, 1

H, 5 Ј-H ), 2 . 47 (dd , 1 H, CH₂CϵCH) pp m. ^{1 3}C N MR

(150.90 MHz, CDCl₃, 25 °C): δ = 138.5–126.1 (arom. C), 102.9 (C-

1Ј), 102.8 (C-1), 101.6 (CЈHPh), 101.4 (CHPh), 81.0 (CH₂CϵCH),

78.2 (C-4 and C-4Ј), 76.8 (C-3), 76.0 (C-3Ј), 75.3 (C-2), 75.1 (C-2Ј),

74.4 (CH₂CϵCH), 71.9 (3Ј-CH₂Ph), 71.0 (3-CH₂Ph), 68.72 (C-6),

68.68 (C-6Ј), 67.6 (C-5), 67.5, (C-5Ј), 60.0 (CH₂CϵCH), 57.4

(OCH₃) ppm. HRMS: calcd. for C₄₄H₄₇O₁₁[M + H]⁺751.3118;

found 751.3115.

Benzyl 3-O-Benzyl-4,6-O-benzylidene-β-D-mannopyranosyl-(1Ǟ2)-

6Јb-H), 3.68 (dd, J_3Ј,4Ј= 8.9 Hz, 1 H, 3Ј-H), 3.39 (ddd, J_5Ј,6Јa

=

C

4.9 Hz, J_5Ј,6Јb= 10.0 Hz, 1 H, 5Ј-H), 3.09 (s, 1 H, 2Ј-OH) ppm. ¹³

3-O-benzyl-4,6-O-benzylidene-α- -mannopyranoside (28): The pro-

D

pargyl deprotection was carried out by starting from disaccharide

22 (0.4 g, 0.48 mmol). Reaction time for 1st step 6 h, for 2nd step

2.5 h. Yield: 0.30 g (80%). [α]_D= –15.0 (c = 1.0, CH₂Cl₂). ¹H NMR

(600.13 MHz, CDCl₃, 25 °C): δ = 7.49–7.25 (m, 25 H, arom. H),

5.56 (s, 1 H, CHPh), 5.47 (s, 1 H, CHЈPh), 4.90 (d, J_1,2= 1.6 Hz,

1 H, 1-H), 4.82 and 4.75 (each d, J = –12.3 Hz, each 1 H, 3-

CH₂Ph), 4.80 and 4.75 (each d, J = –11.8 Hz, each 1 H, 3Ј-CH₂Ph),

4.71 and 4.49 (each d, J = –11.9 Hz, each 1 H, 1-CH₂Ph), 4.67 (d,

J_1Ј,2Ј= 1.3 Hz, 1 H, 1Ј-H), 4.43 (dd, J_2,3= 3.5 Hz, 1 H, 2-H), 4.24

(dd, J_3Ј,4Ј= 9.1 Hz, 1 H, 4Ј-H), 4.210 (dd, J_6a,6b= –10.3 Hz, 1 H,

NMR (150.90 MHz, CDCl₃, 25 °C): δ = 138.1–126.0 (arom. C),

100.4 (CHPh), 100.3 (CЈHPh), 97.6 (C-1Ј), 86.7 (C-1), 78.7 (C-4),

78.6 (C-4Ј), 75.1 (C-3Ј), 73.5 (C-3), 73.4 (C-2), 71.5 (3-CH₂Ph),

71.4 (3Ј-CH₂Ph), 68.5 (C-2Ј), 67.6 (C-6Ј), 67.4 (C-6), 65.8 (C-5Ј),

64.2 (C-5) ppm. HRMS: calcd. for C₄₆H₄₆O₁₀S [M]⁺790.2812;

found 790.2826.

Cyclohexyl 3-O-Benzyl-4,6-O-benzylidene-β-

D-manno-pyranosyl-

(1Ǟ2)-3-O-benzyl-4,6-O-benzylidene-α- -manno-pyranoside (31):

D

Propargyl deprotection was carried out by starting from disaccha-

ride 25 (92 mg, 0.11 mmol). Reaction time for 1st step 5.5 h, for

2nd step 3 h. Yield: 74 mg (85%). [α]_D= –15.1 (c = 0.1, CHCl₃).

¹H NMR (600.13 MHz, CDCl₃, 25 °C): δ = 7.50–7.28 (m, 20 H,

arom. H), 5.55 (s, 1 H, CHPh), 5.48 (s, 1 H, CHЈPh), 4.95 (d, J_1,2

= 1.7 Hz, 1 H, 1-H), 4.83 and 4.76 (each d, J = –12.3 Hz, each 1

H, 3-CH₂Ph), 4.81 and 4.76 (each d, J = –11.7 Hz, each 1 H, 3Ј-

CH₂Ph), 4.74 (d, J_1Ј,2Ј= 1.3 Hz, 1 H, 1Ј-H), 4.34 (dd, J_2,3= 3.4 Hz,

6a-H), 4.207 (dd, J_6Јa,6Јb= –10.4 Hz, 1 H, 6Јa-H), 4.140 (dd, J_4,5

=

9.4 Hz, 1 H, 4-H), 4.139 (dd, J_2Ј,3Ј= 3.7 Hz, 1 H, 2Ј-H), 4.04 (dd,

J_3,4= 9.9 Hz, 1 H, 3-H), 3.85 (ddd, J_5,6a= 4.8 Hz, J_5,6b= 10.4 Hz,

1 H, 5-H), 3.78 (dd, 1 H, 6b-H), 3.73 (dd, 1 H, 6Јb-H), 3.64 (dd,

J_3Ј,4Ј= 9.1 Hz, 1 H, 3Ј-H), 3.34 (ddd, J_5Ј,6Јa= 4.9 Hz, J_5Ј,6Јb

=

10.0 Hz, 1 H, 5Ј-H), 3.22 (br. s, 1 H, 2Ј-OH) ppm. ¹³C NMR

(150.90 MHz, CDCl₃, 25 °C): δ = 138.7–126.0 (arom. C), 101.4

(CHPh), 101.3 (CЈHPh), 98.2 (C-1Ј), 97.9 (C-1), 78.8 (C-4), 78.4

(C-4Ј), 76.0 (C-3Ј), 74.2 (C-3), 72.8 (C-2), 72.6 (3Ј-CH₂Ph), 72.4 (3-

CH₂Ph), 69.4 (C-2Ј), 69.1 (1-CH₂Ph), 68.4, (C-6), 68.3 (C-6Ј), 66.8

(C-5Ј), 63.9 (C-5) ppm. HRMS: calcd. for C_{4 7}H_{4 8}O_{1 1}

[M]⁺788.3197; found 788.3211.

1 H, 2-H), 4.27 (dd, J_4Ј,5Ј= 9.5 Hz, 1 H, 4Ј-H), 4.26 (dd, J_6Јa,6Јb

=

–10.3 Hz, 1 H, 6Јa-H), 4.21 (dd, J_6a,6b= –10.3 Hz, 1 H, 6a-H), 4.16

(ddd, J_2Ј,3Ј= 3.8 Hz, J_2Ј,2Ј-OH= 3.1 Hz, 1 H, 2Ј-H), 4.11 (dd, J_4,5

= 9.2 Hz, 1 H, 4-H), 4.02 (dd, J_3,4= 9.9 Hz, 1 H, 3-H), 3.87 (ddd,

J_5,6a= 4.8 Hz, J_5,6b= 10.4 Hz, 1 H, 5-H), 3.76 (dd, 1 H, 6b-H),

3.76 (dd, 1 H, 6Јb-H), 3.67 (dd, J_3Ј,4Ј= 9.0 Hz, 1 H, 3Ј-H), 3.57

(m, 1 H, OCHC₅H₁₀), 3.40 (ddd, J_5Ј,6Јa= 4.9 Hz, J_5Ј,6Јb= 10.0 Hz,

1 H, 5Ј-H), 3.22 (d, 1 H, 2Ј-OH), 1.80–1.65 (m, 4 H, OCHC₅H₁₀),

1.55–1.15 (m, 6 H, OCHC₅H₁₀) ppm. ¹³C NMR (150.90 MHz,

CDCl₃, 25 °C): δ = 139.4–126.0 (arom. C), 101.4 (CHPh and

CЈHPh), 98.3 (C-1Ј), 96.7 (C-1), 79.0 (C-4), 78.5 (C-4Ј), 76.3 (C-

3Ј), 75.5 (OCHC₅H₁₀), 74.8 (C-3), 73.9 (C-2), 72.6 (3-CH₂Ph and

3Ј-CH₂Ph), 68.8 (C-2Ј), 68.7 (C-6 and C-6Ј), 66.9 (C-5Ј), 64.0 (C-

5), 33.3, 31.3, 25.5, 24.0 (OCHC₅H₁₀) ppm. HRMS: calcd. for

C₄₆H₅₂O₁₁Na [M + Na]⁺803.3402; found 803.3380. HRMS: calcd.

for C₄₆H₅₂O₁₁K [M + K]⁺819.3141; found 819.3105.

Methyl 3-O-Benzyl-4,6-O-benzylidene-β-

D-mannopyranosyl-(1Ǟ2)-

3-O-benzyl-4,6-O-benzylidene-α- -mannopyranoside (29): The pro-

D

pargyl deprotection was carried out as outlined in the general pro-

cedure by starting from disaccharide 24 (0.20 g, 0.26 mmol). Reac-

tion time for 1st step 5 h, for 2nd step 2 h. Yield: 0.16 g (85%). [α]

= –48.5 (c = 1.0, CH₂Cl₂). ¹H NMR (600.13 MHz, CDCl₃,

D

25 °C): δ = 7.49–7.24 (m, 20 H, arom. H), 5.56 (s, 1 H, CHPh),

5.50 (s, 1 H, CHЈPh), 4.84 and 4.77 (each d, J = –12.3 Hz, each 1

H, 3-CH₂Ph) 4.77 and 4.74 (each d, J = –12.0 Hz, each 1 H, 3Ј-

CH₂Ph), 4.72 (d, J_1Ј,2Ј= 1.2 Hz, 1 H, 1Ј-H), 4.71 (d, J_1,2= 1.6 Hz,

1 H, 1-H), 4.38 (dd, J_2,3= 3.5 Hz, 1 H, 2-H), 4.28 (dd, J_6Јa,6Јb

=

–10.4 Hz, 1 H, 6Јa-H), 4.27 (dd, J_4Ј,5Ј= 9.4 Hz, 1 H, 4Ј-H), 4.23

(dd, J_6a,6b= –10.3 Hz, 1 H, 6a-H), 4.17 (ddd, J_2Ј,3Ј= 3.8 Hz, J_2Ј,2Ј-

Methyl 3-O-Benzyl-4,6-O-benzylidene-β-

D-mannopyranosyl-(1Ǟ2)-

3-O-benzyl-4,6-O-benzylidene-β- -mannopyranoside (32): The pro-

D

= 0.79 Hz, 1 H, 2Ј-H), 4.11 (dd, J_4,5= 9.3 Hz, 1 H, 4-H), 3.95 pargyl deprotection was carried out by starting from disaccharide

OH

(dd, J_3,4= 10.0 Hz, 1 H, 3-H), 3.781 (dd, 1 H, 6Јb-H), 3.779 (dd, 27 (0.1 g, 0.13 mmol). Reaction time for 1st step 5 h, for 2nd step

1 H, 6b-H), 3.76 (ddd, J_5,6a= 5.0 Hz, J_5,6b= 10.4 Hz, 1 H, 5-H),

3.67 (dd, J_3Ј,4Ј= 9.1 Hz, 1 H, 3Ј-H), 3.39 (ddd, J_5Ј,6Јa= 4.8 Hz,

3 h. Yield: 68 mg (72%). [α]_D= –108.0 (c = 1.0, CH₂Cl₂). ¹H NMR

(600.13 MHz, CDCl₃, 25 °C): δ = 7.53–7.28 (m, 20 H, arom. H),

880

www.eurjoc.org

Eur. J. Org. Chem. 2009, 870–888

Synthesis of β-(1Ǟ2)-Linked Oligomannosides

5.584 (s, 1 H, CHPh), 5.579 (s, 1 H, CHЈPh), 4.91 (d, J_1Ј,2Ј= 1.1 Hz,

1Ј-H), 4.85 and 4.83 (each d, J = –12.6 Hz, each 1 H, 3-CH₂Ph),

4.754 and 4.746 (each d, J = –12.3 Hz, each 1 H, 3Ј-CH₂Ph), 4.39

(d, J_1,2= 0.95 Hz, 1 H, 1-H), 4.34 (dd, J_2,3= 3.4 Hz, 1 H, 2-H), 4.33

(dd, J_6Јa,6Јb= –10.3 Hz, 1 H, 6Јa-H), 3.32 (dd, J_6a,6b= –10.4 Hz, 1

H, 2ЈЈ-H), 4.52 (dd, J_CH

CH_2aCϵCH), 4.49 (dd, J

= 2.4 Hz, J_CH

= –15.9 Hz, 1 H,

_2a,CH_2b

_2a,CH

= 2.4 Hz, 1 H, CH_2bCϵCH), 4.38

CH_2b,CH

(dd, J_2Ј,3Ј= 3.1 Hz, 1 H, 2Ј-H), 4.37 (dd, J_6Јa,6Јb= –10.4 Hz, 1 H,

6Јa-H), 4.35 (dd, J_{6ЈЈa,6ЈЈb}= –10.5 Hz, 1 H, 6ЈЈa-H), 4.29 (dd, J_2,3

= 3.5 Hz, 1 H, 2-H), 4.26 (dd, J_6a,6b= –10.3 Hz, 1 H, 6a-H), 4.20

(dd, J_4Ј,5Ј= 9.3 Hz, 1 H, 4Ј-H), 4.16 (dd, J_4ЈЈ,5ЈЈ= 9.3 Hz, 1 H, 4ЈЈ-

H), 3.97 (dd, 1 H, 6ЈЈb-H), 3.94 (dd, J_3,4= 10.0 Hz, 1 H, 3-H), 3.91

(dd, 1 H, 6Јb-H), 3.88 (dd, J_4,5= 9.3 Hz, 1 H, 4-H), 3.78 (ddd, J_5,6a

H, 6a-H) 4.27 (dd, J_2Ј,3Ј= 3.3 Hz, 1 H, 2Ј-H), 4.26 (dd, J_4Ј,5Ј

=

9.4 Hz, 1 H, 4Ј-H), 4.09 (dd, J_4,5= 9.3 Hz, 1 H, 4-H), 3.87 (dd, 1

H, 6b-H), 3.85 (dd, 1 H, 6Јb-H), 3.64 (dd, J_3Ј,4Ј= 9.5 Hz, 1 H, 3Ј-

H), 3.63 (dd, J_3,4= 9.9 Hz, 1 H, 3-H), 3.51 (s, 3 H, OCH₃), 3.38 = 4.8 Hz, J_5,6b= 10.4 Hz, 1 H, 5-H), 3.75 (dd, 1 H, 6b-H), 3.64

(ddd, J_5Ј,6Јa= 4.9 Hz, J_5Ј,6Јb= 10.1 Hz, 1 H, 5Ј-H), 3.33 (ddd, J_5,6a(dd, J_3Ј,4Ј= 9.8 Hz, 1 H, 3Ј-H), 3.54 (dd, J_3ЈЈ,4ЈЈ= 9.9 Hz, 1 H, 3ЈЈ-

= 4.8 Hz, J_5,6b= 10.1 Hz, 1 H, 5-H), 3.03 (br. s, 1 H, 2Ј-OH) ppm. H), 3.43 (ddd, J_5ЈЈ,6ЈЈa= 4.8 Hz, J_5ЈЈ,6ЈЈb= 10.1 Hz, 1 H, 5ЈЈ-H), 3.38

¹³C NMR (150.90 MHz, CDCl₃, 25 °C): δ = 138.3–125.8 (arom. (ddd, J_5Ј,6Јa= 4.7 Hz, J_5Ј,6Јb= 9.9 Hz, 1 H, 5Ј-H), 3.36 (s, 3 H,

C), 102.3 (C-1), 101.45 (CЈHPh) 101.49 (CHPh), 100.3 (C-1Ј), 78.4 OCH₃), 2.31 (dd, 1 H, CH₂CϵCH) ppm. ¹³C NMR (150 MHz,

(C-4Ј), 78.0 (C-4), 76.2 (C-3 and C-3Ј), 72.8 (C-2), 72.1 (3-CH₂Ph),

CDCl₃, 25 °C): δ = 137.6–126.0 (arom. C), 102.4 (C-1Ј), 102.0

71.6 (3Ј-CH₂Ph), 69.1 (C-2Ј), 68.6 (C-6Ј), 68.4 (C-6), 67.3 (C-5Ј), (CHPh), 101.7 (CЈHPh), 101.3 (CЈЈHPh), 99.4 (C-1ЈЈ), 98.7 (C-1),

67.0 (C-5), 57.4 (OCH₃) ppm. HRMS: calcd. for C₄₁H₄₄O₁₁[M]⁺

712.2883; found 712.2875.

81.2 (CH₂CϵCH), 78.9 (C-4), 78.5 (C-3ЈЈ), 78.3 (C-4Ј), 77.9 (C-

4ЈЈ), 75.7 (C-3Ј), 75.5 (C-2Ј), 75.3 (C-2ЈЈ), 74.2 (CH₂CϵCH), 74.0

(C-3), 73.6 (C-2), 72.1 (3ЈЈ-CH₂Ph), 71.7 (3-CH₂Ph), 71.1 (3Ј-

CH₂Ph), 68.9 (C-6), 68.7 (C-6ЈЈ), 68.7 (C-6Ј), 67.9 (C-5Ј), 67.8 (C-

5ЈЈ), 63.8 (C-5), 60.2 (CH₂CϵCH), 55.1 (OCH₃) ppm. HRMS:

calcd. for C₆₄H₆₆O₁₆Na [M + Na]⁺1113.4248; found 1113.4347.

Benzyl 3-O-Benzyl-4,6-O-benzylidene-2-O-(prop-2-ynyl)-β-

nopyranosyl-(1Ǟ2)-3-O-benzyl-4,6-O-benzylidene-β- -mannopyr-

anosyl-(1Ǟ2)-3-O-benzyl-4,6-O-benzylidene-α- -mannopyranoside

D-man-

D

(37): The coupling reaction was carried out by starting from donor

19 (0.15 mg, 0.30 mmol). Yield: 0.26 g (72%). [α]_D= –63.8 (c =

0.66, CH₂Cl₂). ¹H NMR (600.13 MHz, CDCl₃, 25 °C): δ = 7.52–

Benzyl 3-O-Benzyl-4,6-O-benzylidene-β-

3-O-benzyl-4,6-O-benzylidene-β- -mannopyranosyl-(1Ǟ2)-3-O-ben-

-mannopyranoside (39): The propargyl de-

D-mannopyranosyl-(1Ǟ2)-

D

7.11 (m, 35 H, arom. H), 5.592 (s, 1 H, CHЈPh), 5.588 (s, 1 H, zyl-4,6-O-benzylidene-α-

D

CHЈЈPh), 5.57 (s, 1 H, CHPh), 5.14 (dd, J_1ЈЈ,2ЈЈ= 0.93 Hz, 1 H, 1ЈЈ-

H), 4.90 (dd, J_1,2= 1.5 Hz, 1 H, 1-H), 4.80 and 4.75 (each d, J =

–12.5 Hz, each 1 H, 3Ј-CH₂Ph), 4.74 and 4.69 (each d, J =

protection was carried out by starting from trisaccharide 37 (0.24 g,

0.21 mmol). Reaction time for 1st step 6.5 h, for 2nd step 3 h.

Yield: 0.19 g (83%). [α]_D= –39.0 (c = 0.66, CH₂Cl₂). ¹H NMR

–12.8 Hz, each 1 H, 3-CH₂Ph), 4.71 and 4.49 (each d, J = –11.9 Hz, (600.13 MHz, CDCl₃, 25 °C): δ = 7.50–7.16 (m, 35 H, arom. H),

each 1 H, 1-CH₂Ph), 4.63 and 4.49 (each d, J = –12.2 Hz, each 1 5.582 (s, 1 H, CHPh), 5.577 (s, 1 H, CHЈЈPh), 5.52 (s, 1 H, CHЈPh),

H, 3ЈЈ-CH₂Ph), 4.56 (dd, J_1Ј,2Ј= 0.87 Hz, 1 H, 1Ј-H), 4.50 (dd, 5.08 (d, J_1Ј,2Ј= 0.91 Hz, 1 H, 1Ј-H), 4.90 (d, J_1,2= 1.6 Hz, 1 H, 1-

J_CH

= 2.4 Hz, J_CH

= –16.0 Hz, 1 H, CH_2aCϵCH), 4.49

H), 4.77 (s, 2 H, 3Ј-CH₂Ph) 4.72 and 4.49 (each d, J = –11.9 Hz,

each 1 H, 1-CH₂Ph), 4.71 and 4.65 (each d, J = –11.9 Hz, each 1

H, 3-CH₂Ph), 4.60 and 4.58 (each d, J = –12.0 Hz, each 1 H, 3ЈЈ-

_2a,CH

_2a,CH_2b

(dd, J_2ЈЈ,3ЈЈ= 3.2 Hz, 2ЈЈ-H), 4.47 (dd, J_CH

CH_2bCϵCH), 4.35 (dd, J_2Ј,3Ј= 3.0 Hz, 2Ј-H), 4.34 (dd, J_{6ЈЈa,6ЈЈb}

= 2.3 Hz, 1 H,

_2b,CH

=

–10.3 Hz, 1 H, 6ЈЈa-H), 4.33 (dd, J_6Јa,6Јb= –10.2 Hz, 1 H, 6Јa-H),

4.30 (dd, J_2,3= 3.5 Hz, 2-H), 4.22 (dd, J_6a,6b= –10.3 Hz, 1 H, 6a-

H), 4.17 (dd, J_4Ј,5Ј= 9.3 Hz, 1 H, 4Ј-H), 4.15 (dd, J_4ЈЈ,5ЈЈ= 9.2 Hz,

1 H, 4ЈЈ-H), 4.01 (dd, J_3,4= 10.0 Hz, 1 H, 3-H), 3.96 (dd, 1 H,

6ЈЈb-H), 3.92 (dd, J_4,5= 9.4 Hz, 1 H, 4-H), 3.89 (dd, 1 H, 6Јb-H),

3.86 (ddd, J_5,6a= 4.8, J_5,6b= 10.3 Hz, 1 H, 5-H), 3.75 (dd, 1 H, 6b-

H), 3.61 (dd, J_3Ј,4Ј= 9.8 Hz, 1 H, 3Ј-H), 3.52 (dd, J_3ЈЈ,4ЈЈ= 9.9 Hz, 1

H, 3ЈЈ-H), 3.41 (ddd, J_5ЈЈ,6ЈЈa= 4.7 Hz, J_5ЈЈ,6ЈЈb= 10.2 Hz, 1 H, 5ЈЈ-

CH₂Ph), 4.58 (d, J_1ЈЈ,2ЈЈ= 0.81 Hz, 1 H, 1-H), 4.37 (dd, J_2Ј,3Ј=

3.3 Hz, 1 H, 2Ј-H), 4.354 (dd, J_2ЈЈ,3ЈЈ= 3.3 Hz, 1 H, 2ЈЈ-H), 4.349

(dd, J_{6ЈЈa,6ЈЈb}= –10.4 Hz, 1 H, 6ЈЈa-H), 4.31 (dd, J_2,3= 3.5 Hz, 1

H, 2-H), 4.26 (dd, J_6Јa,6Јb= –10.3 Hz, 1 H, 6Јa-H), 4.24 (dd, J_4ЈЈ,5ЈЈ

= 9.4 Hz, 1 H, 4ЈЈ-H), 4.20 (dd, J_6a,6b= –10.3 Hz, 1 H, 6a-H), 4.18

(dd, J_4Ј,5Ј= 9.4 Hz, 1 H, 4Ј-H), 4.00 (dd, J_3,4= 10.0 Hz, 1 H, 3-

H), 3.96 (dd, J_4,5= 9.5 Hz, 1 H, 4-H), 3.90 (dd, 1 H, 6ЈЈb-H), 3.86

(ddd, J_5,6a= 4.7 Hz, J_5,6b= 10.3 Hz, 1 H, 5-H), 3.85 (dd, 6Јb-H),

H), 3.32 (ddd, J_5Ј,6Јa= 4.7 Hz, J_5Ј,6Јb= 10.1 Hz, 1 H, 5Ј-H), 2.31 3.71 (dd, 1 H, 6b-H), 3.63 (dd, J_3Ј,4Ј= 9.8 Hz, 1 H, 3Ј-H), 3.52 (dd,

(dd, 1 H, CH₂CϵCH) ppm. ¹³C NMR (150.90 MHz, CDCl₃,

25 °C): δ = 138.4–126.0 (arom. C), 102.4 (C-1ЈЈ), 101.9 (CHPh),

101.6 (CЈHPh), 101.3 (CЈЈHPh), 99.4 (C-1Ј), 96.9 (C-1), 81.2

J_3ЈЈ,4ЈЈ= 9.5 Hz, 1 H, 3ЈЈ-H), 3.40 (ddd, J_5ЈЈ,6ЈЈa= 4.8 Hz, J_5ЈЈ,6ЈЈb=

10.1 Hz, 1 H, 5ЈЈ-H), 3.29 (ddd, J_5Ј,6Јa= 4.8 Hz, J_5Ј,6Јb= 10.0 Hz,

1 H, 5Ј-H) ppm. ¹³C NMR (150.90 MHz, CDCl₃, 25 °C): δ =

(CH₂CϵCH), 78.9 (C-4), 78.4 (C-3ЈЈ), 78.2 (C-4Ј), 77.9 (C-4ЈЈ), 138.4–126.0 (arom. C), 101.7 (CЈHPh), 101.5 (CHPh), 101.4

75.6 (C-3Ј), 75.4 (C-2Ј), 75.3 (C-2ЈЈ), 74.3 (C-3), 74.2 (CH₂CϵCH), (CЈЈHPh), 100.8 (C-1Ј), 99.2 (C-1ЈЈ), 96.9 (C-1), 78.7 (C-4), 78.3

73.8 (C-2), 72.0 (3ЈЈ-CH₂Ph), 71.9 (3-CH₂Ph), 71.1 (3Ј-CH₂Ph), (C-4ЈЈ), 78.1 (C-4Ј), 77.5 (C-3ЈЈ), 76.2 (C-3Ј), 74.0 (C-3), 73.9 (C-

69.6 (1-CH₂Ph), 68.8 (C-6), 68.7 (C-6ЈЈ), 68.6 (C-6Ј), 67.8 (C-5Ј), 2), 73.9 (C-2Ј), 72.1, 71.7, 71.6, 69.5 (4ϫCH₂Ph), 68.9 (C-2ЈЈ), 68.8

67.8 (C-5ЈЈ), 64.2 (C-5), 60.2 (CH₂CϵCH) ppm. HRMS: calcd. for

(C-6), 68.8 (C-6ЈЈ), 68.4 (C-6Ј), 67.7 (C-5ЈЈ), 67.3 (C-5Ј), 64.1 (C-5)

ppm. HRMS: calcd. for C₆₇H₆₈O₁₆Na [M + Na]⁺1151.4405; found

1151.4433.

C₇₀H₇₁O₁₆[M + H]⁺1167.4742; found 1167.4723.

Methyl 3-O-Benzyl-4,6-O-benzylidene-2-O-(prop-2-ynyl)-β-

nopyranosyl-(1Ǟ2)-3-O-benzyl-4,6-O-benzylidene-β- -mannopyr-

anosyl-(1Ǟ2)-3-O-benzyl-4,6-O-benzylidene-α- -mannopyranoside

D-man-

D

Methyl 3-O-Benzyl-4,6-O-benzylidene-β-

3-O-benzyl-4,6-O-benzylidene-β- -mannopyranosyl-(1Ǟ2)-3-O-ben-

zyl-4,6-O-benzylidene-α- -mannopyranoside (40): The propargyl de-

protection was carried out as outlined in the general procedure by

D-mannopyranosyl-(1Ǟ2)-

D

(38): The coupling reaction was carried out by starting from donor

19 (64 mg, 0.13 mmol). Yield: 0.103 g (74%). [α]_D= –97.0 (c = 1.0,

D

CH₂Cl₂). ¹H NMR (600.13 MHz, CDCl₃, 25 °C): δ = 7.52–7.12 (m, starting from trisaccharide 38 (33.5 mg, 0.031 mmol). Reaction

30 H, arom. H), 5.61 (s, 1 H, CHЈPh), 5.60 (s, 1 H, CHЈЈPh), 5.56

(s, 1 H, CHPh), 5.15 (d, J_1Ј,2Ј= 0.81 Hz, 1 H, 1Ј-H), 4.81 and 4.76 –72.0 (c = 1.0, CH₂Cl₂). H NMR (600.13 MHz, CDCl₃, 25 °C): δ

time for 1st step 7 h, for 2nd step 3 h. Yield: 26 mg (81%). [α]_D=

1

(each d, J = –12.6 Hz, each 1 H, 3Ј-CH₂Ph), 4.74 and 4.68 (each

d, J = –12.5 Hz, each 1 H, 3-CH₂Ph), 4.71 (d, J_1,2= 1.5 Hz, 1 H,

1-H), 4.65 and 4.50 (each d, J = –11.8 Hz, each 1 H, 3ЈЈ-CH₂Ph),

= 7.50–7.14 (m, 30 H, arom. H.), 5.60 (s, 1 H, CHЈPh), 5.58 (s, 1

H, CHЈЈPh), 5.51 (s, 1 H, CHPh), 5.10 (d, J_1Ј,2Ј= 1.1 Hz, 1 H, 1Ј-

H), 4.79 (s, 2 H, 3ЈЈ-CH₂Ph), 4.71 (d, J_1,2= 1.5 Hz, 1 H, 1-H), 4.71

4.64 (d, J_1ЈЈ,2ЈЈ= 0.84 Hz, 1 H, 1-HЈЈ), 4.53 (dd, J_2ЈЈ,3ЈЈ= 3.2 Hz, 1 and 4.63 (each d, J = –12.0 Hz, each 1 H, 3Ј-CH₂Ph), 4.65 (d,

Eur. J. Org. Chem. 2009, 870–888

www.eurjoc.org

881

M. Poláková, M. U. Roslund, F. S. Ekholm, T. Saloranta, R. Leino

FULL PAPER

J_1ЈЈ,2ЈЈ= 0.61 Hz, 1 H, 1ЈЈ-H), 4.62 and 4.60 (each d, J = –12.0 Hz,

each 1 H, 3-CH₂Ph), 4.39 (dd, J_2ЈЈ,3ЈЈ= 3.3 Hz, 1 H, 2ЈЈ-H), 4.374

crude product was purified by column chromatography (hexane/

EtOAc, 8:1Ǟ3.5:1). The isolated product was repurified by column

(dd, J_2Ј,3Ј= 3.2 Hz, 1 H, 2Ј-H), 4.366 (dd, J_6Јa,6Јb= –10.4 Hz, 1 H, chromatography (hexane/EtOAc, 1:1) to afford the title compound.

6Јa-H), 4.31 (dd, J_6a,6b= –10.4 Hz, 1 H, 6a-H), 4.28 (dd, J_2,3

3.3 Hz, 1 H, 2-H), 4.25 (dd, J_4Ј,5Ј= 9.3 Hz, 1 H, 4Ј-H), 4.24 (dd,

J_{6ЈЈa,6ЈЈb}= –9.9 Hz, 1 H, 6ЈЈa-H), 4.20 (dd, J_4ЈЈ,5ЈЈ= 9.5 Hz, 1 H,

=

Yield: 0.103 g (82%). [α]_D= +5.5 (c = 1.0, CH₂Cl₂). ¹H NMR

(500.13 MHz, CDCl₃, 30 °C): δ = 7.52–7.28 (m, 25 H, arom. H.),

5.65 (dd, J_1,2= 1.8 Hz, J_P,1-H= 6.2 Hz, 1 H, 1-H), 5.58 (s, 1 H,

3

4ЈЈ-H), 3.93 (dd, J_4,5= 9.2 Hz, 1 H, 4-H), 3.92 (dd, J_3,4= 10.0 Hz, CHPh), 5.08 and 5.03 [each d, J = –11.9 Hz, J_P,CH= 9.9 Hz,

2a

1 H, 3-H), 3.91 (dd, 1 H, 6Јb-H), 3.89 (dd, 1 H, 6b-H), 3.77 (ddd, J_P,CH= 9.3 Hz, each 1 H, PO(OCH₂Ph)], 5.04 and 5.01 [each d,

2b

J_5,6a= 4.9 Hz, J_5,6b= 10.1 Hz, 1 H, 5-H), 3.71 (dd, 1 H, 6ЈЈb-H),

3.67 (dd, J_3Ј,4Ј= 9.7 Hz, 1 H, 3Ј-H), 3.55 (dd, J_3ЈЈ,4ЈЈ= 9.5 Hz, 1

H, 3ЈЈ-H), 3.42 (ddd, J_5ЈЈ,6ЈЈa= 4.6 Hz, J_5ЈЈ,6ЈЈb= 10.2 Hz, 1 H, 5ЈЈ-

J = –11.8 Hz, J_P,CH= 8.8 Hz, J_P,CH= 8.4 Hz, each 1 H,

2

a

2

b

PO(OCH₂Ph)], 4.75 and 4.57 (each d, J = –12.2 Hz, each 1 H, 3-

CH₂Ph), 4.71 and 4.64 (each d, J = –12.0 Hz, each 1 H, 2-CH₂Ph),

4.21 (dd, J_4,5= 9.6 Hz, 1 H, 4-H), 4.04 (dd, J_6a,6b= –10.3 Hz, 1 H,

6a-H), 3.855 (ddd, J_5,6a= 4.9 Hz, J_5,6b= 10.3 Hz, 1 H, 5-H), 3.846

(dd, J_3,4= 10.1 Hz, 1 H, 3-H), 3.76 (dd, 1 H, 6b-H), 3.73 (dd, J_2,3

= 3.2 Hz, 1 H, 2-H) ppm. ¹³C NMR (125.77 MHz, CDCl₃, 30 °C):

H), 3.363 (s, 3 H, OCH₃), 3.362 (ddd, J_5Ј,6Јa= 4.9 Hz, J_5Ј,6Јb

=

10.0 Hz, 1 H, 5Ј-H) ppm. ¹³C NMR (150.90 MHz, CDCl₃, 25 °C):

δ = 138.5–126.0 (arom. C), 101.8 (CHPh), 101.5 (CЈHPh), 101.4

(CЈЈHPh), 100.9 (C-1Ј), 99.3 (C-1ЈЈ), 98.8 (C-1), 78.7 (C-4), 78.3

(C-4Ј), 78.1 (C-4ЈЈ), 77.5 (C-3ЈЈ), 76.2 (C-3Ј), 74.0 (C-2ЈЈ), 73.8 (C- δ = 138.4–126.2 (arom. C), 101.6 (CHPh), 97.0 (²J_P,C-1= 6.0 Hz,

2), 73.8 (C-3), 72.2 (3-CH₂Ph), 71.7 (3ЈЈ-CH₂Ph), 71.5 (3Ј-CH₂Ph),

C-1), 78.4 (C-4), 76.2 (³J_P,C-2= 9.6 Hz, C-2), 75.2 (C-3), 73.7 (2-

68.9 (C-2), 68.9 (C-6ЈЈ), 68.8 (C-6Ј), 68.4 (C-6) 67.7 (C-5Ј), 67.3 (C- CH₂Ph), 73.1 (3-CH₂Ph), 69.6 [²J_P,C= 5.5 Hz, PO(OCH₂Ph)], 68.3

5ЈЈ), 63.7 (C-5), 55.0 (OCH₃) ppm. HRMS: calcd. for C₆₁H₆₄O₁₆Na (C-6), 67.3 [²J_P,C= 5.7 Hz, PO(OCH₂Ph)], 65.8 (C-5) ppm. ³¹P

[M + Na]⁺1075.2589; found 1075.2575.

NMR (202.47 MHz, CDCl₃, 30 °C): δ = –3.17 ppm. HRMS: calcd.

for C₄₁H₄₂O₉P [M + H]⁺709.2566; found 709.2522.

2,3-Di-O-Benzyl-4,6-O-benzylidene- -mannopyranose (44): To a

D

solution of 43 (0.16 g, 0.3 mmol, 1 equiv.) dissolved in acetone/

water (50:1, 5 mL:0.1 mL) and cooled to 0 °C was added NBS

(0.11 g, 0.62 mmol, 2.1 equiv.) in one portion. The mixture was

warmed up to room temperature and after 30 min the reaction was

quenched by the addition of solid Na₂S₂O₃(23 mg, 0.13 mmol,

0.5 equiv.). The solvent was evaporated, and the residue was diluted

with CH₂Cl₂(20 mL) and washed with water (2ϫ15 mL), dried,

and concentrated. Chromatography (hexane/EtOAc, 6:1Ǟ2:1) gave

the desired product (55 mg, 62%). α/β, Ͼ10:1. Data for the α-an-

omer: ¹H NMR (600.13 MHz, CDCl₃, 25 °C): δ = 7.53–7.26 (m,

15 H, arom. H.), 5.65 (s, 1 H, CHPh), 5.51 (d, J_1,2= 1.4 Hz, 1 H,

1-H), 4.82 and 4.66 (each d, J = –12.2 Hz, each 1 H, 3-CH₂Ph),

4.76 (s, 2 H, 2-CH₂Ph), 4.32 (dd, J_4,5= 9.4 Hz, 1 H, 4-H), 4.28

Phenyl 2,3-di-O-Benzyl-4,6-O-benzylidene-β-

(1Ǟ2)-3-O-benzyl-4,6-O-benzylidene-1-thio-α-

D

-manno-pyranosyl-

-mannopyranoside

D

(47): Disaccharide 30 (0.15 g, 0.19 mmol, 1 equiv.) was dissolved in

dry DMF (1.5 mL) and the solution was then cooled to 0 °C. So-

dium hydride (60% in oil, 10 mg, 0.25 mmol, 1.3 equiv.) was added.

After stirring for 30 min, benzyl bromide (39 mg, 27 µL,

0.22 mmol, 1.2 equiv.) was added, and the mixture was warmed up

to room temperature. After 1.5 h, the reaction was quenched by the

addition of methanol. The solvent was evaporated, and the residue

was diluted with EtOAc (20 mL) and washed with water

(3 ϫ 20 mL) and brine (1 ϫ 20 mL), dried, and concentrated.

Chromatography (hexane/EtOAc, 8:1) gave the title compound.

Yield: 0.16 g (96%). [α]_D= –3.5 (c = 0.166, CH₂Cl₂). ¹H NMR

(600.13 MHz, CDCl₃, 25 °C): δ = 7.51–7.25 (m, 30 H, arom. H),

5.60 (s, 1 H, CHPh), 5.51 (s, 1 H, CHЈPh), 5.49 (d, J_1,2= 1.5 Hz,

1 H, 1-H), 5.04 and 4.96 (each d, J = –12.3 Hz, each 1 H, 3Ј-

CH₂Ph), 4.80 and 4.76 (each d, J = –12.1 Hz, each 1 H, 3-CH₂Ph),

4.69 and 4.61 (each d, J = –12.5 Hz, each 1 H, 2Ј-CH₂Ph), 4.62 (d,

J_1Ј,2Ј= 0.93 Hz, 1 H, 1Ј-H), 4.51 (dd, J_2,3= 3.2 Hz, 1 H, 2-H), 4.33

(ddd, J_5,6a= 4.8 Hz, J_5,6b= 10.2 Hz, 1 H, 5-H), 4.22 (dd, J_6a,6b

=

–10.3 Hz, 1 H, 6a-H), 4.04 (dd, J_2,3= 3.2 Hz, 1 H, 2-H), 3.97 (dd,

J_3,4= 9.4 Hz, 1 H, 3-H), 3.89 (dd, 1 H, 6b-H) ppm. ¹³C NMR

(150.90 MHz, CDCl₃, 25 °C): δ = 138.4–126.1 (arom C), 101.5

(CHPh), 87.1 (C-1), 79.1 (C-4), 78.1 (C-2), 76.2 (C-3), 73.1 (3-

CH₂Ph), 73.0 (2-CH₂Ph), 68.5 (C-6), 65.4 (C-5) ppm. Data for the

β-anomer: ¹H NMR (600.13 MHz, CDCl₃, 25 °C): δ = 7.53–7.26

(m, 15 H, arom. H.), 5.64 (s, 1 H, CHPh), 4.81 (d, J_1,2= 1.2 Hz, 1

H, 1-H), 5.11 and 4.86 (each d, J = –11.1 Hz, each 1 H, 3-CH₂Ph),

4.86 and 4.74 (each d, J = –11.1 Hz, each 1 H, 2-CH₂Ph), 4.31 (dd,

J_4,5= 9.4 Hz, 1 H, 4-H), 4.29 (dd, J_6a,6b= –10.5 Hz, 1 H, 6a-H),

4.18 (dd, J_2,3= 3.1 Hz, 1 H, 2-H), 3.95 (dd, 1 H, 6b-H), 3.74 (dd,

J_3,4= 9.7 Hz, 1 H, 3-H), 3.42 (ddd, J_5,6a= 4.9 Hz, J_5,6b= 9.8 Hz,

1 H, 5-H) ppm. HRMS: calcd. for C₂₇H₂₈O₆[M + Na]⁺449.1964;

found 449.1964.

(ddd, J_5,6a= 4.8 Hz, J_5,6b= 10.2 Hz, 1 H, 5-H), 4.25 (dd, J_4Ј,5Ј

=

9.3 Hz, 1 H, 4Ј-H), 4.25 (dd, J_6Јa,6Јb= –10.4 Hz, 1 H, 6Јa-H), 4.23

(dd, J_6a,6b= –10.2 Hz, 1 H, 6a-H), 4.17 (dd, J_4,5= 9.5 Hz, 1 H, 4-

H), 3.98 (dd, J_3,4= 10.0 Hz, 1 H, 3-H), 3.97 (dd, J_2Ј,3Ј= 3.2 Hz, 1

H, 2Ј-H), 3.87 (dd, 1 H, 6Јb-H), 3.79 (dd, 1 H, 6b-H), 3.59 (dd,

J_3Ј,4Ј= 9.9 Hz, 1 H, 3Ј-H), 3.31 (ddd, J_5Ј,6Јa= 4.8 Hz, J_5Ј,6Јb

=

10.1 Hz, 1 H, 5Ј-H) ppm. ¹³C NMR (150.90 MHz, CDCl₃, 25 °C):

δ = 138.5–126 (arom. C), 101.7 (CЈHPh), 101.4 (CHPh), 99.8 (C-

1Ј), 86.4 (C-1), 78.7 (C-4), 78.4 (C-4Ј), 77.5 (C-3Ј), 76.2 (C-2), 76.0

(C-2Ј), 74.6 (3Ј-CH₂Ph), 74.3 (C-3), 72.3 (2Ј-CH₂Ph), 71.5 (3-

CH₂Ph), 68.6 (C-6), 68.5 (C-6Ј), 67.8 (C-5Ј), 65.4 (C-5) ppm.

HRMS: calcd. for C₅₅H₅₁O₁₀S [M – H]^–903.3203; found 903.3810.

(2,3-Di-O-Benzyl-4,6-O-benzylidene-α-D-mannopyranosyl) Dibenzyl

Phosphate (45): To a solution of compound 44 (80 mg, 0.18 mmol,

1 equiv.) in dry CH₂Cl₂(4 mL) was added 1H-tetrazole (0.45  in

acetonitrile, 47 mg, 1.8 mL, 0.67 mmol, 3.75 equiv.). After cooling

the reaction mixture to –40 °C, dibenzyl(N,N-diisopropyl)phos-

phoramidite (0.15 g, 0.15 mL, 0.45 mmol, 2.5 equiv.) was added

dropwise, and the mixture was slowly warmed up to room tempera-

ture (45 min) followed by stirring for 1 h. Next, the reaction was

cooled to –60 °C and m-CPBA (77 %, 0.1 mg, 0.45 mmol,

2.5 equiv.) was added. The mixture was stirred for 30 min at 0 °C

and then for 45 min with slow warming to room temperature. The

reaction mixture was diluted with CH₂Cl₂(40 mL), washed with

10 % solution Na₂S₂O₃(2 ϫ 15 mL), saturated NaHCO₃

(2ϫ15 mL), and water (2ϫ10 mL), dried, and concentrated. The

2,3-Di-O-Benzyl-4,6-O-benzylidene-β-

D-mannopyranosyl-(1Ǟ2)-3-

O-benzyl-4,6-O-benzylidene- -mannopyranose (48): Compound 47

D

(0.10 g, 0.11 mmol, 1 equiv.) was dissolved in acetone/water (33:1,

5 mL:0.15 mL). The solution was cooled to 0 °C and NBS (24 mg,

0.14 mmol, 1.2 equiv.) was added in one portion. The mixture was

warmed up to room temperature and after 30 min the reaction was

quenched by the addition of solid Na₂S₂O₃(13 mg, 0.09 mmol,

0.75 equiv.). The solvent was evaporated, and the residue was di-

luted with CH₂Cl₂(20 mL) and washed with water (2ϫ15 mL),

dried, and concentrated. Chromatography (hexane/EtOAc,

882

www.eurjoc.org

Eur. J. Org. Chem. 2009, 870–888

Synthesis of β-(1Ǟ2)-Linked Oligomannosides

6:1Ǟ2:1) gave the desired product (55 mg, 62%). The product ob-

tained was used in the next step without detailed NMR spectro-

scopic characterization as a result of the complexity of both the ¹H

Methyl 2-O-Acetyl-3,4,6-tri-O-benzyl-β-

D-glucopyranosyl-(1Ǟ2)-3-

O-benzyl-4,6-O-benzylidene-α- -mannopyranoside (53): The coup-

D

ling was carried out as outlined in the general procedure by starting

and ¹³C NMR spectra of the anomeric disaccharide mixture. from donor 51 (0.36 g, 0.56 mmol). Yield: 0.32 g (80 %). [α]_D

=

HRMS: calcd. for C₄₇H₄₈O₁₁Na [M + Na]⁺811.3089; found

811.3070. HRMS: calcd. for C₄₇H₄₈O₁₁K [M + K]⁺827.2828;

found 827.2861.

–10.0 (c = 1.0, CH₂Cl₂). H NMR (600.13 MHz, CDCl₃, 25 °C): δ

1

= 7.51–7.18 (m, 25 H, arom. H), 5.60 (s, 1 H, CHPh), 5.12 (dd,

J_2Ј,3Ј= 9.6 Hz, 1 H, 2Ј-H), 4.80 and 4.56 (each d, J = –10.8 Hz,

each 1 H, CH₂Ph), 4.80 and 4.69 (each d, J = –11.5 Hz, each 1 H,

CH₂Ph), 4.78 and 4.68 (each d, J = –12.5 Hz, each 1 H, CH₂Ph),

[2,3-Di-O-Benzyl-4,6-O-benzylidene-β-

O-benzyl-4,6-O-benzylidene-α-

D-mannopyranosyl-(1Ǟ2)-3-

-mannopyranosyl] Dibenzyl Phos- 4.62 (d, J_1,2= 1.7 Hz, 1 H, 1-H), 4.53 and 4.51 (each d, J =

D

phate (49): To a solution of compound 48 (46 mg, 0.058 mmol,

1 equiv.) in dry CH₂Cl₂(3 mL) was added 1H-tetrazole (0.45  in

acetonitrile, 15.3 mg, 0.6 mL, 0.22 mmol, 3.75 equiv.). After cool-

ing the reaction mixture to –40 °C, dibenzyl(N,N-diisopropyl)phos-

phoramidite (50 mg, 49 µL, 0.15 mmol, 2.5 equiv.) was added drop-

wise, and the reaction mixture was slowly warmed up to room tem-

perature (45 min) followed by stirring for 1 h. Next, the reaction

mixture was cooled to –60 °C and m-CPBA (77 %, 66 mg,

0.30 mmol, 5.0 equiv.) was added. The reaction mixture was stirred

for 30 min at 0 °C and then for 45 min with slow warming to room

–12.1 Hz, each 1 H, CH₂Ph), 4.41 (d, J_1Ј,2Ј= 7.9 Hz, 1 H, 1Ј-H),

4.19 (dd, J_6a,6b= –10.1 Hz, 1 H, 6a-H), 4.11 (dd, J_2,3= 3.2 Hz, 1

H, 2-H), 4.09 (dd, J_4,5= 9.5 Hz, 1 H, 4-H), 3.87 (dd, J_3,4= 10.0 Hz,

1 H, 3-H), 3.77 (dd, 1 H, 6b-H), 3.75 (dd, J_6Јa,6Јb= –10.9 Hz, 1 H,

6Јa-H), 3.69 (ddd, J_5,6a= 4.7 Hz, J_5,6b= 10.3 Hz, 1 H, 5-H), 3.674

(dd, J_3Ј,4Ј= 8.9 Hz, 1 H, 3Ј-H), 3.672 (dd, 1 H, 6Јb-H), 3.64 (dd,

J_4Ј,5Ј= 9.9 Hz, 1 H, 4Ј-H), 3.53 (ddd, J_5Ј,6Јa= 1.8 Hz, J_5Ј,6Јb

=

5.7 Hz, 1 H, 5Ј-H), 3.33 (s, 3 H, OCH₃), 2.04 (s, 3 H, CH₃C=O)

ppm. ^{1 3}C NMR (150.90 MHz, CDCl₃, 25 °C): δ = 169.5

(CH₃C=O), 138.7–126.1 (arom. C), 101.5 (CHPh), 100.2 (C-1Ј),

temperature. The mixture was diluted with CH₂Cl₂(50 mL), 99.5 (C-1), 82.8 (C-3Ј), 78.1 (C-4), 78.0 (C-4Ј), 75.5 (C-2 and C-5Ј),

washed with 10 % solution Na₂S₂O₃(2 ϫ 20 mL), saturated

NaHCO₃(2ϫ20 mL), and water (2ϫ20 mL), dried, and concen-

trated. The crude product was purified by column chromatography

(hexane/EtOAc, 8:1Ǟ3.5:1). The product was repurified by column

chromatography (hexane/EtOAc, 1:1) to afford the title compound.

Yield: 45.5 mg (75%). [α]_D= –25.0 (c = 1.0, MeOH). ¹H NMR

(500.13 MHz, CDCl₃, 25 °C): δ = 7.52–7.24 (m, 35 H, arom. H.),

75.2 (CH₂Ph), 74.9 (CH₂Ph), 73.7 (CH₂Ph, and C-3), 72.9 (C-2Ј),

71.2 (CH₂Ph), 69.4 (C-6Ј), 68.8 (C-6), 64.1 (C-5), 54.9 (OCH₃), 21.0

(CH₃C=O) ppm. HRMS: calcd. for C₅₀H₅₄O₁₂846.3615

[M]⁺; found 846.3594.

Methyl 2-O-Acetyl-3,4,6-tri-O-benzyl-β-

O-benzyl-4,6-O-benzylidene-β- -mannopyranosyl-(1Ǟ2)-3-O-ben-

zyl-4,6-O-benzylidene-α- -mannopyranoside (60): The coupling was

D-glucopyranosyl-(1Ǟ2)-3-

D

3

D

5.580 (s, 1 H, CHPh), 5.579 (dd, J_1,2= 1.9 Hz, J_P,1-H= 6.2 Hz, 1

carried out as outlined in the general procedure by starting from

H, 1-H), 5.42 (s, 1 H, CHЈPh), 5.08 and 5.03 [each d, J = –11.7 Hz,

J_P,CH= 8.8 Hz, J_P,CH= 8.4 Hz, each 1 H, PO(OCH₂Ph)_a], 5.00

donor 51 (0.12 g, 0.18 mmol). Yield: 0.14 g (78%). [α]_D= –60.0 (c

2a

2b

1

= 1.0, CH₂Cl₂). H NMR (600.13 MHz, CDCl₃, 25 °C): δ = 7.50–

and 4.98 [each d, J = –11.7 Hz, J_P,CH= 9.6 Hz, J_P,CH= 8.4 Hz,

2b

each 1 H, PO(OCH₂Ph)_b], 4.99 and ²4^a.91 (each d, J = –12.2 Hz,

each 1 H, CH₂Ph), 4.69 and 4.68 (each d, J = –12.4 Hz, each 1 H,

CH₂Ph), 4.68 and 4.62 (each d, J = –12.3 Hz, each 1 H, CH₂Ph),

4.44 (d, J_1Ј,2Ј= 0.97 Hz, 1 H, 1Ј-H), 4.22 (dd, J_6Јa,6Јb= –10.1 Hz,

7.12 (m, 35 h, arom. H), 5.58 (s, 1 H, CHЈPh), 5.56 (s, 1 H, CHPh),

5.21 (dd, J_2ЈЈ,3ЈЈ= 9.5 Hz, 1 H, 2ЈЈ-H), 4.96 (dd, J_1ЈЈ,2ЈЈ= 7.9 Hz, 1

H, 1ЈЈ-H), 4.88 and 4.67 (each d, J = –13.0 Hz, each 1 H, 3Ј-

CH₂Ph), 4.80 and 4.53 (each d, J = –10.8 Hz, each 1 H, 4ЈЈ-

CH₂Ph), 4.78 and 4.68 (each d, J = –11.5 Hz, each 1 H, 3ЈЈ-

CH₂Ph), 4.69 and 4.62 (each d, J = –12.1 Hz, each 1 H, 3-CH₂Ph),

4.52 and 4.48 (each d, J = –12.0 Hz, each 1 H, 6ЈЈ-CH₂Ph), 4.67

(d, J_1,2= 1.8 Hz, 1 H, 1-H), 4.50 (dd, J_1Ј,2Ј= 0.84 Hz, 1 H, 1Ј-H),

4.30 (dd, J_6a,6b= –10.2 Hz, 1 H, 6a-H), 4.28 (dd, J_2Ј,3Ј= 3.2 Hz, 1

1 H, 6Јa-H), 4.21 (dd, J_4Ј,5Ј= 9.3 Hz, 1 H 4Ј-H), 4.06 (dd, J_4,5

=

9.6 Hz, 1 H, 4-H), 4.05 (dd, J_2,3= 3.4 Hz, 1 H, 2-H), 4.04 (dd,

J_6a,6b= –10.3 Hz, 1 H, 6a-H), 3.91 (dd, J_2Ј,3Ј= 3.2 Hz, 1 H, 2Ј-H),

3.85 (ddd, J_5,6a= 4.8 Hz, J_5,6b= 10.2 Hz, 1 H, 5-H), 3.84 (dd, J_3,4

= 10.1 Hz, 1 H, 3-H), 3.83 (dd, 1 H, 6Јb-H), 3.65 (dd, 1 H, 6b-H),

3.55 (dd, J_3Ј,4Ј= 9.9 Hz, 1 H, 3Ј-H), 3.23 (ddd, J_5Ј,6Јa= 4.8 Hz,

J_5Ј,6Јb= 10.1 Hz, 1 H, 5Ј-H) ppm. ¹³C NMR (150.90 MHz, CDCl₃,

25 °C): δ = 138.6–126.1 (arom. C), 101.6 (CЈHPh), 101.4 (CHPh),

101.0 (C-1Ј), 96.3 (²J_P,C-1= 5.4 Hz, C-1), 78.3 (C-4Ј), 77.9 (C-4),

77.4 (C-3Ј), 76.0 (C-2Ј), 75.4 (³J_P,C-2= 9.9 Hz, C-2), 74.7 (CH₂Ph),

H, 2Ј-H), 4.26 (dd, J_4,5= 9.4 Hz, 1 H, 4-H), 4.16 (dd, J_6Јa,6Јb

=

–10.3 Hz, 1 H, 6Јa-H), 4.09 (dd, J_2,3= 3.1 Hz, 1 H, 2-H), 4.06 (dd,

J_4Ј,5Ј= 9.3 Hz, 1 H, 4Ј-H), 3.91 (dd, J_3,4= 10.0 Hz, 1 H, 3-H), 3.79

(ddd, J_5,6a= 4.7 Hz, J_5,6b= 10.3 Hz, 1 H, 5-H), 3.77 (dd, J_{6ЈЈa,6ЈЈb}

= –10.6 Hz, 1 H, 6ЈЈa-H), 3.76 (dd, 1 H, 6b-H), 3.75 (dd, 1 H, 6Јb-

H), 3.70 (dd, J_3ЈЈ,4ЈЈ= 8.8 Hz, 1 H, 3ЈЈ-H), 3.64 (dd, 1 H, 6ЈЈb-H),

3.63 (dd, J_4ЈЈ,5ЈЈ= 9.8 Hz, 1 H, 4ЈЈ-H), 3.62 (ddd, J_5ЈЈ,6ЈЈa= 1.7 Hz,

J_4ЈЈ,6ЈЈb= 6.2 Hz, 1 H, 5ЈЈ-H), 3.55 (dd, J_3Ј,4Ј= 9.9 Hz, 1 H, 3Ј-H),

3.37 (s, 3 H, OCH₃), 3.25 (ddd, J_5Ј,6Јa= 4.8 Hz, J_5Ј,6b= 10.1 Hz, 1

H, 5Ј-H), 1.91 (s, 3 H, 2ЈЈ-CH₃C=O) ppm. ¹³C NMR (150.90 MHz,

CDCl₃, 25 °C): δ = 170.2 (2ЈЈ-CH₃C=O), 138.7–125.9 (arom. C),

101.7 (CHЈPh), 101.3 (CHPh), 101.1 (C-1ЈЈ), 101.0 (C-1Ј), 100.0

(C-1), 83.3 (C-3ЈЈ), 78.5 (C-4), 78.2 (C-5ЈЈ), 77.2 (C-4Ј), 76.9 (C-2),

75.7 (C-3Ј), 75.1 (4ЈЈ-CH₂Ph), 75.0 (C-4ЈЈ and 3ЈЈ-CH₂Ph), 74.5 (C-

3), 74.3 (C-2Ј), 73.6 (6ЈЈ-CH₂Ph), 73.2 (C-2ЈЈ), 71.5 (3-CH₂Ph), 70.4

(3Ј-CH₂Ph), 69.9 (C-6ЈЈ), 69.3 (C-6), 68.6 (C-6Ј), 67.7 (C-5Ј), 64.3

(C-5), 55.0 (OCH₃), 21.1 (2ЈЈ-CH₃C=O) ppm. HRMS: calcd. for

C₇₀H₇₄O₁₇Na [M + Na]⁺1209.4824; found 1209.4978.

73.1 (C-3), 72.3 (CH₂Ph), 71.6 (CH₂Ph), 69.8 and 69.7 [²J_{P, C}

=

5.5 Hz, PO(OCH₂Ph)], 68.4 (C-6Ј), 68.3 (C-6), 67.6 (C-5Ј), 65.8 (C-

5) ppm. ³¹P NMR (242.94 MHz, CDCl₃, 25 °C): δ = –2.95 ppm.

HRMS: calcd. for C₆₁H₆₁O₁₄PNa [M + Na]⁺1071.3696; found

1071.3743.

General Procedure for the Coupling of the Acceptor with the Gluco-

pyranosyl Imidate Donor: A mixture of trichloroacetimidate 51

(1.2 equiv.), acceptor 16 or 29 (1 equiv.), and 4 Å molecular sieves

(0.3 g) was dried under reduced pressure for 2 h. Dry CH₂Cl₂

(10 mL) was added, and the solution was stirred for 30 min at room

temperature under an argon atmosphere. The mixture was then co-

oled to –10 °C and TMSOTf (0.05 equiv.) was added; stirring was

continued for a further 30 min, after which the temperature was

brought up to room temperature. The reaction mixture was neutral-

ized by the addition of Et₃N and concentrated. The residue was

purified by column chromatography (hexane/EtOAc, 6:1Ǟ4:1) to

give the title compound.

Methyl 3,4,6-Tri-O-benzyl-β-

D-glucopyranosyl-(1Ǟ2)-3-O-benzyl-

4,6-O-benzylidene-α- -mannopyranoside (54): To a solution of di-

D

saccharide 53 (0.24 g, 0.28 mmol) in dry MeOH/THF (3:1, 12 mL)

was added 2% MeONa (8.5 mg, 0.4 mL, 0.37 mmol, 1.3 equiv.),

Eur. J. Org. Chem. 2009, 870–888

www.eurjoc.org

883

M. Poláková, M. U. Roslund, F. S. Ekholm, T. Saloranta, R. Leino

FULL PAPER

and the mixture was stirred for 18 h at room temperature. The sol-

for C₆₈H₇₂O₁₆Na [M + Na]⁺1167.4713; found 1167.4691. HRMS:

vent was evaporated, and the residue was dissolved in EtOAc calcd. for C₆₈H₇₂O₁₆K [M + K]⁺1183.4453; found 1183.4452.

(40 mL) and washed with saturated NaHCO₃(2 ϫ 10 mL) and

Methyl 3,4,6-Tri-O-acetyl-2-deoxy-2-phthalimido-β-

D-gluco-pyran-

water (10 mL), dried, and concentrated. The crude product was

purified by column chromatography (hexane/EtOAc, 3:1) to give

the desired product. Yield: 0.22 g (98 %). [α]_D= +9.5 (c = 1.0,

CH₂Cl₂). ¹H NMR (600.13 MHz, CDCl₃, 25 °C): δ = 7.54–7.12 (m,

25 H, arom. H), 5.65 (s, 1 H, CHPh), 4.93 and 4.71 (each d, J =

–11.2 Hz, each 1 H, 3Ј-CH₂Ph), 4.91 and 4.74 (each d, J =

–11.4 Hz, each 1 H, 6Ј-CH₂Ph), 4.87 and 4.57 (each d, J =

–10.8 Hz, each 1 H, 4Ј-CH₂Ph), 4.77 (d, J_1,2= 1.7 Hz, 1 H, 1-H),

4.55 and 4.49 (each d, J = –12.1 Hz, each 1 H, 3-CH₂Ph), 4.51 (d,

J_1Ј,2Ј= 8.4 Hz, 1 H, 1Ј-H), 4.28 (dd, J_6a,6b= –10.4 Hz, 1 H, 6a-H),

4.21 (ddd, J_2,3= 3.4 Hz, J_2,2-OH= 2.5 Hz, 1 H, 2-H), 4.19 (dd, J_4,5

= 9.5 Hz, 1 H, 4-H), 3.99 (dd, J_3,4= 9.9 Hz, 1 H, 3-H), 3.88 (dd,

osyl-(1Ǟ2)-3-O-benzyl-4,6-O-benzylidene-α- -manno-pyranoside

D

(56): A suspension of 4 Å molecular sieves (0.3 g), collidine (42 mg,

46 µL, 0.35 mmol, 1.3 equiv.), AgOTf (83 mg, 0.32 mmol,

1.2 equiv.), and acceptor 16 (0.1 g, 0.27 mmol) in dry CH₂Cl₂

(3 mL) was stirred under an argon atmosphere for 2 h. The reaction

mixture was cooled to –20 °C, and a solution of 52 (0.15 g,

0.29 mmol, 1.1 equiv.) in dry CH₂Cl₂(1 mL) was added dropwise.

The mixture was stirred at –20 °C for 40 min, then warmed up

slowly to room temperature, and filtered through a pad of Celite.

The filtrate was diluted with CH₂Cl₂(25 mL), washed with satu-

rated NaHCO₃(2ϫ20 mL), brine (20 mL), and water (20 mL),

dried, and concentrated. Purification of the residue by column

chromatography (hexane/EtOAc, 4:1Ǟ1:1) gave the title disaccha-

ride. Yield: 0.17 g (78%). [α]_D= –21.5 (c = 1.0, CH₂Cl₂). ¹H NMR

(600.13 MHz, CDCl₃, 25 °C): δ = 7.88 (m, 2 H, phth. H), 7.75 (m,

1 H, 6b-H), 3.83 (d, 1 H, 2-OH), 3.79 (ddd, J_5,6a= 4.8 Hz, J_5,6b

10.4 Hz, 1 H, 5-H), 3.72 (dd, 1 H, 6Јb-H), 3.6872 (dd, J_6Јa,6Јb

=

–11.2 Hz, 1 H, 6Јa-H), 3.6871 (dd, J_2Ј,3Ј= 9.1 Hz, 1 H, 2Ј-H), 3.59

(dd, J_4Ј,5Ј= 9.8 Hz, 1 H, 4Ј-H), 3.58 (dd, J_3Ј,4Ј= 8.9 Hz, 1 H, 3Ј-

H), 3.48 (ddd, J_5Ј,6Јa= 2.0 Hz, J_5Ј,6Јb= 4.2 Hz, 1 H, 5Ј-H), 3.32 (s,

3 H, OCH₃) ppm. ¹³C NMR (150.90 MHz, CDCl₃, 25 °C): δ =

138.9–126.0 (arom. C), 101.64 (C-1), 101.62 (CHPh) 101.5 (C-1Ј),

83.9 (C-3Ј), 79.6 (C-4), 77.0 (C-4Ј), 75.9 (C-5Ј), 74.9 (4Ј-CH₂Ph),

74.5 (3Ј-CH₂Ph), 74.5 (C-3), 74.2 (6Ј-CH₂Ph), 73.5 (3-CH₂Ph), 71.6

(C-2), 71.5 (C-2Ј), 69.0 (C-6Ј), 68.9 (C-6), 63.6 (C-5), 55.0 (OCH₃)

ppm. HRMS: calcd. for C₄₈H₅₂O₁₁[M]⁺804.3509; found 804.3487.

2 H, phth. H), 7.44–7.23 (m, 10 H, arom. H), 5.88 (dd, J_3Ј,4Ј

=

9.1 Hz, 1 H, 3Ј-H), 5.45 (s, 1 H, CHPh), 5.45 (d, J_1Ј,2Ј= 8.5 Hz, 1

H, 1Ј-H), 5.20 (dd, J_4Ј,5Ј= 10.1 Hz, 1 H, 4Ј-H), 4.71 and 4.65 (each

d, J = –12.3 Hz, each 1 H, CH₂Ph), 4.50 (dd, J_2Ј,3Ј= 10.8 Hz, 1 H,

2Ј-H), 4.39 (d, J_1,2= 1.8 Hz, 1 H, 1-H), 4.31 (dd, 1 H, 6Јb-H), 4.23

(dd, J_6Јa,6Јb= –12.2 Hz, 1 H, 6Јa-H), 4.11 (dd, J_2,3= 3.2 Hz, 1 H,

2-H), 3.88 (dd, J_4,5= 9.6 Hz, 1 H, 4-H), 3.88 (ddd, J_5Ј,6Јa= 2.4 Hz,

J_5Ј,6Јb= 4.9 Hz, 1 H, 5Ј-H), 3.82 (dd, J_3,4= 10.0 Hz, 1 H, 3-H),

3.75 (dd, J_6a,6b=–10.2 Hz, 1 H, 6a-H), 3.49 (ddd, J_5,6a= 4.7 Hz,

J_5,6b= 10.2 Hz, 1 H, 5-H), 3.17 (s, 3 H, OMe), 3.16 (dd, 1 H, 6b-

H), 2.06, 2.05, 1.90 (each s, each 3 H, 3ϫCH₃C=O) ppm. ¹³C

NMR (150.90 MHz, CDCl₃, 25 °C): δ = 170.7, 170.2, 169.4

(3ϫCH₃C=O), 138.4–123.4 (arom. C), 101.5 (CHPh), 99.0 (C-1),

96.7 (C-1Ј), 78.1 (C-4), 75.2 (C-2), 73.8 (C-3), 72.1 (C-5Ј), 71.5

(CH₂Ph), 70.4 (C-3Ј), 69.1 (C-4Ј), 68.4 (C-6), 63.7 (C-5), 62.2 (C-

6Ј), 54.9 (OCH₃), 54.5 (C-2Ј), 20.8, 20.7, 20.6 (3ϫCH₃C=O) ppm.

HRMS: calcd. for C₄₁H₄₄NO₁₅[M]⁺790.2711; found 790.2691.

Methyl 3,4,6-Tri-O-benzyl-β-

4,6-O-benzylidene-β- -mannopyranosyl-(1Ǟ2)-3-O-benzyl-4,6-O-

benzylidene-α- -mannopyranoside (61): To a solution of trisaccha-

D-glucopyranosyl-(1Ǟ2)-3-O-benzyl-

D

ride 60 (0.1 g, 0.084 mmol) in dry MeOH/THF (3:1, 12 mL) was

added 1% MeONa (3.1 mg, 0.31 mL, 0.13 mmol, 1.6 equiv.), and

the mixture was stirred for 72 h at room temperature. The solvent

was evaporated, and the residue was dissolved in EtOAc (40 mL)

and washed with saturated NaHCO₃(2 ϫ 10 mL) and water

(10 mL), dried, and concentrated. Purification by column

chromatography (hexane/EtOAc, 3:1) gave the desired product.

Yield: 94 mg (98 %). [α]_D= –73.5 (c = 1.0, CH₂Cl₂). ¹H NMR

Methyl 2-Acetamido-3,4,6-tri-O-acetyl-2-deoxy-β-

D-gluco-pyran-

osyl-(1Ǟ2)-3-O-benzyl-4,6-O-benzylidene-α- -manno-pyranoside

D

(600.13 MHz, CDCl₃, 25 °C): δ = 7.53–7.12 (m, 35 H, arom. H), (57): A mixture of disaccharide 56 (65 mg, 0.08 mmol) and hydraz-

5.66 (s, 1 H, CHPh), 5.56 (s, 1 H, CHЈPh), 5.06 and 4.65 (each d,

J = –11.1 Hz, each 1 H, 3ЈЈ-CH₂Ph), 4.92 and 4.67 (each d, J =

–13.6 Hz, each 1 H, 3Ј-CH₂Ph), 4.84 and 4.49 (each d, J =

–10.7 Hz, each 1 H, 4ЈЈ-CH₂Ph), 4.76 and 4.70 (each d, J =

ine hydrate (0.15 g, 0.15 mL, 3.16 mmol, 40 equiv.) in EtOH (4 mL,

96%) was heated at reflux overnight (15 h). The reaction mixture

was cooled to room temperature and the solvent was evaporated.

The residue was dissolved in pyridine (4 mL) into which acetic an-

–12.5 Hz, each 1 H, 3-CH₂Ph), 4.69 (d, J_1,2= 1.6 Hz, 1 H, 1-H), hydride (2 mL) was added. The mixture was stirred overnight (15 h)

4.64 (d, J_1ЈЈ,2ЈЈ= 7.8 Hz, 1 H, 1ЈЈ-H), 4.59 (d, J_1Ј,2Ј= 0.82 Hz, 1 H, at room temperature, after which it was concentrated. The residue

1Ј-H), 4.48 and 4.44 (each d, J = –12.0 Hz, each 1 H, 6ЈЈ-CH₂Ph),

4.40 (dd, J_4,5= 9.6 Hz, 1 H, 4-H), 4.30 (dd, J_2Ј,3Ј= 3.2 Hz, 1 H,

was diluted with CH₂Cl₂(20 mL), washed with saturated NaHCO₃

(2ϫ10 mL), dried, and concentrated. Column chromatography

gave the title compound. Yield: 50 mg (90%). [α]_D= –12.0 (c =

0.33, CH₂Cl₂). ¹H NMR (600.13 MHz, CDCl₃, 25 °C): δ = 7.40–

7.26 (m, 10 H, arom. H), 5.68 (dd, J_3Ј,4Ј= 9.2 Hz, 1 H, 3Ј-H), 5.63

(d, J_NHAc,2Ј= 7.4 Hz, 1 H, NHAc), 5.62 (s, 1 H, CHPh), 5.15 (d,

2Ј-H), 4.29 (dd, J_6a,6b= –10.3 Hz, 1 H, 6a-H), 4.26 (dd, J_6Јa,6Јb

=

–10.2 Hz, 1 H, 6Јa-H), 4.22 (dd, J_2,3= 3.5 Hz, 1 H, 2-H), 4.12 (dd,

J_4Ј,5Ј= 9.4 Hz, 1 H, 4Ј-H), 3.89 (dd, J_3,4= 10.1 Hz, 1 H, 3-H), 3.81

(dd, 1 H, 6b-H), 3.789 (dd, 1 H, 6Јb-H), 3.786 (ddd, J_2ЈЈ,3ЈЈ

=

8.8 Hz, J_2ЈЈ,5ЈЈ= 1.3 Hz, 1 H, 2ЈЈ-H), 3.76 (ddd, J_5,6a= 4.8 Hz, J_5,6bJ_1Ј,2Ј= 8.4 Hz, 1 H, 1Ј-H), 5.02 (dd, J_4Ј,5Ј= 10.1 Hz, 1 H, 4Ј-H),

= 10.5 Hz, 1 H, 5-H), 3.75 (dd, J_{6ЈЈa,6ЈЈb}= –10.2 Hz, 1 H, 6ЈЈa-H), 4.77 and 4.71 (each d, J = –11.6 Hz, each 1 H, CH₂Ph), 4.64 (d,

3.64 (dddd, J_5ЈЈ,6ЈЈa= 1.8 Hz, J_5ЈЈ,6ЈЈb= 6.6 Hz, 1 H, 5ЈЈ-H), 3.63 J_1,2= 1.7 Hz, 1 H, 1-H), 4.24 (dd, J_6a,6b= –10.3 Hz, 1 H, 6a-H),

(dd, J_3ЈЈ,4ЈЈ= 8.8 Hz, 1 H, 3ЈЈ-H), 3.61 (dd, 1 H, 6ЈЈb-H), 3.57 (dd,

J_3Ј,4Ј= 10.0 Hz, 1 H, 3Ј-H), 3.46 (dd, J_4ЈЈ,5ЈЈ= 9.9 Hz, 1 H, 4ЈЈ-H),

4.23 (dd, 1 H, 6Јb-H), 4.19 (dd, J_6Јa,6Јb= –12.3 Hz, 1 H, 6Јa-H),

4.16 (dd, J_2,3= 3.4 Hz, 1 H, 2-H), 4.09 (dd, J_4,5= 9.4 Hz, 1 H, 4-

3.36 (s, 3 H, OCH₃), 3.30 (ddd, J_5Ј,6Јa= 4.8 Hz, J_5Ј,6Јb= 9.9 Hz, 1 H), 3.95 (dd, J_3,4= 10.0 Hz, 1 H, 3-H), 3.80 (dd, 1 H, 6b-H), 3.763

H, 5Ј-H) ppm. ¹³C NMR (150.90 MHz, CDCl₃, 25 °C): δ = 138.9–

125.9 (arom. C), 105.6 (C-1ЈЈ), 101.7 (CHPh), 101.3 (CЈHPh), 99.4

(C-1), 98.8 (C-1Ј), 86.5 (C-3ЈЈ), 78.3 (C-4), 77.4 (C-4Ј), 77.1 (C-4ЈЈ),

(ddd, J_5Ј,6Јa= 2.4 Hz, J_5Ј,6Јb= 4.9 Hz, 1 H, 5Ј-H), 3.758 (ddd, J_5,6a

= 4.8 Hz, J_5,6b= 10.4 Hz, 1 H, 5-H), 3.50 (ddd, J_2Ј,3Ј= 10.7 Hz,

2Ј-H), 3.36 (s, 3 H, OCH₃), 2.04, 2.03 2.02, 1.80 (each s, each 3

76.8 (C-2Ј), 75.42 (C-3Ј), 75.35 (C-2ЈЈ), 75.3 (3ЈЈ-CH₂Ph), 75.22 H, NHC=OCH₃and 3ϫCH₃C=O) ppm. ¹³C NMR (150.90 MHz,

(6ЈЈ-CH₂Ph), 75.18 (C-3ЈЈ), 73.9 (C-3), 73.6 (C-2), 73.4 (3-CH₂Ph), CDCl₃, 25 °C): δ = 170.7, 170.6, 170.3, 169.6 (NHC=OCH₃and

71.7 (4ЈЈ-CH₂Ph), 70.4 (3Ј-CH₂Ph), 69.9 (C-6ЈЈ), 69.1 (C-6), 68.3 3ϫCH₃C=O), 138.2–126.0 (arom. C), 101.5 (CHPh), 100.2 (C-1),

(C-6Ј), 67.5 (C-5Ј), 63.8 (C-5), 54.9 (OCH₃) ppm. HRMS: calcd. 98.4 (C-1Ј), 78.7 (C-4), 74.4 (C-2), 74.4 (C-3), 72.6 (CH₂Ph), 71.9

884

www.eurjoc.org

Eur. J. Org. Chem. 2009, 870–888

Synthesis of β-(1Ǟ2)-Linked Oligomannosides

(C-5), 71.2 (C-3Ј), 69.0 (C-4Ј), 68.9 (C-6), 63.9 (C-5Ј), 62.2 (C-6Ј),

55.4 (C-2Ј), 55.0 (OCH₃), 23.4, 20.7 (NHC=OCH₃and

3 ϫ CH₃C=O) ppm. HRMS: calcd. for C₃₅H₄₄NO₁₅[M + H]⁺

701.2684; found 701.2706.

= –30.0 (c = 1.0, MeOH). ¹H NMR (600.13 MHz, CD₃OD,

D

25 °C): δ = 4.78 (d, J_1,2= 1.7 Hz, 1 H, 1-H), 4.65 (d, J_1Ј,2Ј= 1.0 Hz,

1 H, 1Ј-H), 4.03 (dd, J_2,3= 3.5 Hz, 1 H, 2-H), 3.89 (dd, J_2Ј,3Ј

=

3.2 Hz, 1 H, 2Ј-H), 3.87 (dd, J_6Јa,6Јb= –12.0 Hz, 1 H, 6Јa-H), 3.83

(dd, J_6a,6b= –11.8 Hz, 1 H, 6a-H), 3.70 (dd, 1 H, 6b-H), 3.68 (dd,

Methyl 2-Acetamido-2-deoxy-β-

D-glucopyranosyl-(1Ǟ2)-3-O-ben-

1 H, 6Јb-H), 3.67 (dd, J_3,4= 9.6 Hz, 1 H, 3-H), 3.61 (dd, J_4,5

=

zyl-4,6-O-benzylidene-α- -mannopyranoside (58): Compound 57

D

9.8 Hz, 1 H, 4-H), 3.53 (dd, J_4Ј,5Ј= 9.7 Hz, 1 H, 4Ј-H), 3.48 (ddd,

J_5,6a= 2.3 Hz, J_5,6b= 5.8 Hz, 1 H, 5-H), 3.45 (dd, J_3Ј,4Ј= 9.4 Hz,

1 H, 3Ј-H), 3.39 (s, 3 H, OCH₃), 3.23 (ddd, J_5Ј,6Јa= 2.3 Hz, J_5Ј,6Јb

= 6.6 Hz, 1 H, 5Ј-H) ppm. ¹³C NMR (150.90 MHz, CD₃OD,

25 °C): δ = 98.7 (C-1), 98.5 (C-1Ј), 77.2 (C-5Ј), 77.0 (C-2Ј), 73.7

(C-3Ј), 73.2 (C-5), 71.2 (C-2Ј), 70.7 (C-3), 67.6 (C-4), 67.1 (C-4Ј),

61.5 (C-6Ј), 61.2 (C-6), 53.8 (OCH₃) ppm. HRMS: calcd. for

C₃₉H₇₂O₃₃Na [3M + Na]⁺1091.3854; found 1091.3820.

(50 mg, 0.076 mmol) was taken up to dry MeOH/THF (3:1, 4 mL)

and treated with tBuOK (16 mg, 0.015 mmol, 2 equiv.). After stir-

ring at room temperature for 15 h, the solvent was evaporated, and

the crude product was purified by column chromatography

(CHCl₃/MeOH, 5:1) to yield the deacetylated compound. Yield:

37 mg (93 %). [α]_D= –57.8 (c = 0.66, CH₂Cl₂). ¹H NMR

(600.13 MHz, CD₃OD, 25 °C): δ = 7.49–7.23 (m, 10 H, arom. H),

5.63 (s, 1 H, CHPh), 4.78 and 4.63 (each d, J = –12.1 Hz, each 1 H,

CH₂Ph), 4.76 (d, J_1,2= 1.7 Hz, 1 H, 1-H), 4.57 (d, J_1Ј,2Ј= 8.4 Hz, 1

Cyclohexyl β-D-Mannopyranosyl-(1Ǟ2)-α-D-mannopyranoside (35):

H, 1Ј-H), 4.24 (dd, J_2,3= 3.3 Hz, 1 H, 2-H), 4.17 (dd, J_6a,6b

=

The reaction was carried out with 31 (22.2 mg, 0.029 mmol) and

Pd/C (43 mg) in MeOH/EtOAc (9:1, 2.2 mL) for 18.5 h. Yield:

12.1 mg (100 %). [α]_D= +0.5 (c = 1.0, MeOH). ¹H NMR

(600.13 MHz, CD₃OD, 25 °C): δ = 5.04 (d, J_1,2= 1.8 Hz, 1 H, 1-

H), 4.66 (d, J_1Ј,2Ј= 1.0 Hz, 1 H, 1Ј-H), 3.98 (dd, J_2,3= 3.4 Hz, 1

–10.1 Hz, 1 H, 6a-H), 4.09 (dd, J_4,5= 9.4 Hz, 1 H, 4-H), 3.91 (dd,

J_6Јa,6Јb= –11.7 Hz, 1 H, 6Јa-H), 3.86 (dd, J_3,4= 10.1 Hz, 1 H, 3-

H), 3.80 (dd, 1 H, 6b-H), 3.71 (dd, 1 H, 6Јb-H), 3.69 (dd, J_2Ј,3Ј

=

10.5 Hz, 1 H, 2Ј-H), 3.67 (ddd, J_5,6a= 4.8 Hz, J_5,6b= 10.4 Hz, 1

H, 5-H), 3.53 (dd, J_3Ј,4Ј= 8.9 Hz, 1 H, 3Ј-H), 3.37 (s, 3 H, O CH₃),

3.36 (dd, J_4Ј,5Ј= 9.8 Hz, 1 H 4Ј-H), 3.32 (ddd, J_5Ј,6Јa= 2.3 Hz,

J_5Ј,6Јb= 5.8 Hz, 1 H, 5Ј-H), 1.98 (s, 3 H, NHC=OCH₃) ppm. ¹³C

NMR (150.90 MHz, CD₃OD, 25 °C): δ = 173.9 (NHC=OCH₃),

139.6–127.4 (arom. C), 103.0 (CHPh), 101.5 (C-1Ј), 100.8 (C-1),

79.3 (C-4), 78.2 (C-5Ј), 75.9 (C-2), 75.5 (C-3), 75.4 (C-3Ј), 72.1 (C-

4Ј), 72.0 (CH₂Ph), 69.9 (C-6), 65.4 (C-5), 63.0 (C-6Ј), 57.6 (C-2Ј),

55.5 (OCH₃), 23.4 (NHC=OCH₃) ppm. HRMS: calcd. for

C₂₉H₃₈NO₁₁[M + Na]⁺576.2444; found 576.2422.

H, 2-H), 3.90 (dd, J_2Ј,3Ј= 3.2 Hz, 1 H, 2Ј-H), 3.87 (dd, J_6Јa,6Јb

=

–12.0 Hz, 1 H, 6Јa-H), 3.80 (dd, J_6a,6b= –11.8 Hz, 1 H, 6a-H), 3.73

(dd, J_3,4= 9.6 Hz, 1 H, 3-H), 3.70 (dd, 1 H, 6b-H), 3.68 (dd, 1 H,

6Јb-H), 3.67 (m, 1 H, OCHC₅H₁₀), 3.63 (dd, J_4,5= 9.8 Hz, 1 H, 4-

H), 3.60 (ddd, J_5,6a= 2.4 Hz, J_5,6b= 5.8 Hz, 1 H, 5-H), 3.54 (dd,

J_4Ј,5Ј= 9.7 Hz, 1 H, 4Ј-H), 3.47 (dd, J_3Ј,4Ј= 9.4 Hz, 1 H, 3Ј-H),

3.24 (ddd, J_5Ј,6Јa= 2.3 Hz, J_5Ј,6Јb= 6.4 Hz, 1 H, 5Ј-H), 1.98–1.82

(m, 2 H, OCHC₅H₁₀), 1.80–1.70 (m, 2 H, OCHC₅H₁₀), 1.55–1.20

(m, 6 H, OCHC₅H₁₀) ppm. ¹³C NMR (150.90 MHz, CD₃OD,

25 °C): δ = 100.0 (C-1Ј), 97.1 (C-1), 79.2 (C-2), 78.6 (C-5Ј), 76.4

(OCHC₅H₁₀), 75.1 (C-3Ј), 74.8 (C-5), 72.6 (C-2Ј), 72.1 (C-3), 69.1

(C-4), 68.5 (C-4Ј), 62.9 (C-6Ј), 62.7 (C-6), 34.5, 32.6, 26.8, 25.2,

25.0 (OCHC₅H₁₀) ppm. HRMS: calcd. for C₁₈H₃₂O₁₁Na

[M + Na]⁺447.1837; found 447.1843.

General Procedure for Hydrogenolysis: Benzyl/benzylidene-pro-

tected di- or trisaccharide (1 wt.equiv.), Pd/C (wet, contains 50%

water; 2.5 wt.equiv.) in dry MeOH was stirred at 3.45 bar of H₂at

room temperature. The mixture was filtered through a pad of Ce-

lite. Evaporation of the solvent provided the crude product.

Methyl β-D-Mannopyranosyl-(1Ǟ2)-β-D-mannopyranoside (36): The

β-D-Mannopyranosyl-(1Ǟ2)-D-mannopyranose (33): The reaction

reaction was carried out with 32 (30 mg, 0.042 mmol) and Pd/C

(75 mg) in MeOH (3 mL) for 19 h. Yield: 14 mg (94%). [α]_D= –70.0

(c = 1.0, MeOH). ¹H NMR (600.13 MHz, CD₃OD, 25 °C): δ =

4.73 (d, J_1Ј,2Ј= 0.86 Hz, 1 H, 1Ј-H), 4.48 (d, J_1,2= 0.80 Hz, 1 H,

1Ј-H), 4.12 (dd, J_2,3= 3.4 Hz, 1 H, 2-H), 3.96 (dd, J_2Ј,3Ј= 3.2 Hz,

1 H, 2Ј-H), 3.89 (dd, J_6a,6b= –11.8 Hz, 1 H, 6a-H), 3.86 (dd, J_6Јa,6Јb

= –12.0 Hz, 1 H, 6Јa-H), 3.71 (dd, 1 H, 6b-H), 3.67 (dd, 1 H, 6Јb-

H), 3.52 (dd, J_4,5= 9.7 Hz, 1 H, 4-H), 3.50 (dd, J_4Ј,5Ј= 9.7 Hz, 1 H,

4Ј-H), 3.46 (dd, J_3,4= 9.6 Hz, 1 H, 3-H), 3.40 (dd, J_3Ј,4Ј= 9.4 Hz, 1

was carried out with compound 28 (25 mg, 0.032 mmol) and Pd/C

(62.5 mg) in MeOH (3 mL) for 16 h. Crude product 33 (10 mg,

93%) was obtained and purified further by graphite solid-phase

extraction as follows: A sample of mannobiose (1 mg) was dis-

solved in water (100 µL) and applied to a column of graphitized

carbon (150 mg, Carbograph Extract-clean column, Alltech) condi-

tioned with ethanol and water. The column was washed with water

(8 mL), and the disaccharide was eluted with 20% aqueous acetoni-

trile (4 mL) and finally dried in a vacuum centrifuge. The α/β ratio

of 33 in CD₃OD was approximately 3:1 at 20 °C. ¹H NMR

(600.13 MHz, CD₃OD, 20 °C): δ = 5.19 (d, J_1,2= 1.8 Hz, 1 H, 1-

H), 4.64 (d, J_1Ј,2Ј= 1.0 Hz, 1 H, 1Ј-H), 4.01 (dd, J_2,3= 3.3 Hz, 1

H, 3Ј-H), 3.52 (s, 3 H, OCH₃), 3.21 (ddd, J_5,6a= 2.3 Hz, J_5,6b

=

6.0 Hz, 5-H), 3.18 (ddd, J_5Ј,6Јa= 2.3 Hz, J_5Ј,6Јb= 6.6 Hz, 5Ј-H)

ppm. ¹³C NMR (150.90 MHz, CD₃OD, 25 °C): δ = 103.3 (C-1),

102.1 (C-1Ј), 78.8 (C-2), 78.62, (C-5Ј), 78.60 (C-5), 75.2 (C-3Ј), 74.7

(C-3), 72.1 (C-2Ј), 69.1 (C-4), 68.6 (C-4Ј), 63.0 (C-6Ј), 62.8 (C-6),

57.6 (OCH₃) ppm. HRMS: calcd. for C₃₉H₇₂O₃₃Na [3M + Na]⁺

1091.3853; found 1091.3825.

H, 2-H), 3.90 (dd, J_2Ј,3Ј= 3.2 Hz, 1 H, 2Ј-H), 3.87 (dd, J_6Јa,6Јb

–12.1 Hz, 1 H, 6Јa-H), 3.79 (dd, J_6a,6b= –11.7 Hz, 1 H, 6a-H), 3.77

(dd, J_3,4= 9.6 Hz, 1 H, 3-H), 3.73 (ddd, J_5,6a= 2.4 Hz, J_5,6b

=

5.3 Hz, 1 H, 5-H), 3.72 (dd, 1 H, 6b-H), 3.68 (dd, 1 H, 6Јb-H), 3.64

(dd, J_4,5= 9.6 Hz, 1 H, 4-H), 3.53 (dd, J_4Ј,5Ј= 9.7 Hz, 1 H, 4Ј-H),

3.46 (dd, J_3Ј,4Ј= 9.5 Hz, 1 H, 3Ј-H), 3.23 (ddd, J_5Ј,6Јa= 2.3 Hz,

J_5Ј,6Јb= 6.5 Hz, 1 H, 5Ј-H) ppm. ¹³C NMR (150.90 MHz, CD₃OD,

20 °C): δ = 100.0 (C-1Ј), 93.3 (C-1), 79.5 (C-2), 78.6 (C-5Ј), 75.1

(C-3Ј), 74.1 (C-5), 72.6 (C-2Ј), 71.7 (C-3), 69.1 (C-4), 68.5 (C-4Ј),

62.9 (C-6Ј), 62.7 (C-6) ppm. HRMS (ESI-TOF): calcd. for

C₃₆H₆₆O₃₃Na [3M + Na]⁺1049.3384; found 1049.3357.

β-D-Mannopyranosyl-(1Ǟ2)-β-D-mannopyranosyl-(1Ǟ2)-D-manno-

pyranose (41): The reaction was carried out with 39 (40 mg,

0.035 mmol) and Pd/C (100 mg) in MeOH (2.5 mL) for 21 h. Crude

yield: 17 mg (96%). Compound 41 was further purified by HPLC

(Hypercarb 5 µm, 4ϫ125-mm). The column was eluted iso-

cratically with 5% acetonitrile in water for 1 min and with a gradi-

ent from 5 to 60% acetonitrile over the course of 19 min at a flow

rate of 0.7 mLmin^–1. The α/β ratio of 41 in CD₃OD was approxi-

mately 3:1 at 20 °C. Data for the α-anomer: ¹H NMR

Methyl β-D-Mannopyranosyl-(1Ǟ2)-α-D-mannopyranoside (34): The

reaction was carried out with 29 (60 mg, 0.084 mmol) and Pd/C

(150 mg) in MeOH (6 mL) for 19 h. Yield: 28 mg (93%). The ¹³C (600.13 MHz, CD₃OD, 20 °C): δ = 5.18 (d, J_1,2= 1.9 Hz, 1 H, 1-

NMR spectroscopic data for 34 in D₂O was reported earlier.^[37][α]

H), 4.86 (d, J_1ЈЈ,2ЈЈ= 1.1 Hz, 1 H, 1ЈЈ-H), 4.72 (d, J_1Ј,2Ј= 0.80 Hz,

Eur. J. Org. Chem. 2009, 870–888

www.eurjoc.org

885

M. Poláková, M. U. Roslund, F. S. Ekholm, T. Saloranta, R. Leino

FULL PAPER

1 H, 1Ј-H), 4.13 (dd, J_2Ј,3Ј= 3.6 Hz, 1 H, 2Ј-H), 4.07 (dd, J_2ЈЈ,3ЈЈ

3

=

(500.13 MHz, D₂O 25 °C): δ = 5.32 (dd, J_1,2= 2.0 Hz, J_P,1-H

=

4

2.78 Hz, 1 H, 2ЈЈ-H), 3.97 (dd, J_2,3= 3.2 Hz, 1 H, 2-H), 3.87 (dd, 7.7 Hz, 1 H, 1-H), 3.87 (dd, J_2,3= 3.4 Hz, J_P,2-H= 0.51 Hz, 1 H,

J_6Јa,6Јb= –11.8 Hz, 1 H, 6Јa-H), 3.86 (dd, J_{6ЈЈa,6ЈЈb}= –12.0 Hz, 1 H,

6ЈЈa-H), 3.81 (dd, J_3,4= 9.6 Hz, 1 H, 3-H), 3.78 (dd, J_6a,6b

–11.6 Hz, 1 H, 6a-H), 3.73 (dd, 1 H, 6b-H), 3.71 (dd, 1 H, 6Јb-H),

3.70 (ddd, J_5,6a= 2.3 Hz, J_5,6b= 4.7 Hz, 5-H), 3.66 (dd, 1 H, 6ЈЈb-

H), 3.57 (dd, J_4,5= 9.9 Hz, 1 H, 4-H), 3.56 (dd, J_4Ј,5Ј= 9.5 Hz, 1

2-H), 3.80 (dd, J_3,4= 9.9 Hz, 1 H, 3-H), 3.77 (dd, J_6a,6b= –12.3 Hz,

1 H, 6a-H), 3.72 (ddd, J_5,6a= 2.3 Hz, J_5,6b= 5.8 Hz, 1 H, 5-H),

3.66 (dd, 1 H, 6b-H), 3.57 (dd, J_4,5= 9.9 Hz, 1 H, 4-H) ppm. ¹³C

NMR (125.77 MHz, D₂O, 30 °C): δ = 96.6 (²J_P,C-1= 5.5 Hz, C-1),

74.1 (C-5), 71.0 (³J_P,C-2= 8.9 Hz, C-2), 70.4 (C-3), 67.0 (C-4), 61.4

(C-6) ppm. ³¹P NMR (202.47 MHz, D₂O, 30 °C): δ = –2.4 ppm.

HRMS: calcd. for C₆H₁₃O₉P [M]⁺260.0297; found 260.0289.

=

H, 4Ј-H), 3.50 (dd, J_4ЈЈ,5ЈЈ= 9.5 Hz, 1 H, 4ЈЈ-H), 3.49 (dd, J_3ЈЈ,4ЈЈ

=

9.6 Hz, 1 H, 3ЈЈ-H), 3.48 (dd, J_3Ј,4Ј= 9.7 Hz, 1 H, 3Ј-H), 3.236

(ddd, J_5Ј,6Јa= 2.3 Hz, J_5Ј,6Јb= 5.8 Hz, 5Ј-H), 3.235 (ddd, J_5ЈЈ,6ЈЈa

= 2.3 Hz, J_5ЈЈ,6ЈЈb= 6.5 Hz, 5ЈЈ-H) ppm. ¹³C NMR (150.90 MHz,

CD₃OD, 20 °C): δ = 102.2 (C-1ЈЈ), 100.8 (C-1Ј), 93.7 (C-1), 80.8

(C-2), 79.3 (C-2Ј), 78.44, (C-5ЈЈ), 78.40 (C-5Ј), 75.0 (C-3ЈЈ), 74.4

(C-3Ј), 74.1 (C-5), 72.1 (C-2ЈЈ), 71.3 (C-3), 69.5 (C-4), 68.66 (C-

4ЈЈ), 68.62 (C-4Ј), 63.1 (C-6ЈЈ), 62.6 (C-6), 62.4 (C-6Ј) ppm. Data

for the β-anomer: ¹H NMR (600.13 MHz, CD₃OD, 20 °C): δ =

4.94 (d, J_1ЈЈ,2ЈЈ= 0.96 Hz, 1 H, 1ЈЈ-H), 4.83 (d, J_1,2= 0.87 Hz, 1 H,

1-H), 4.80 (d, J_1Ј,2Ј= 0.85 Hz, 1 H, 1Ј-H), 4.33 (dd, J_2Ј,3Ј= 3.4 Hz,

β-D-Mannopyranosyl-(1Ǟ2)-α-D-mannopyranosyl Phosphate (50):

The reaction was carried out as outlined in the general procedure

for hydrogenolysis. Compound 49 (35 mg, 0.033 mmol) and Pd/C

(87.5 mg) in MeOH (3.5 mL) for 18 h. Yield: 14 mg (70%). [α]_D

=

+30.0 (c = 0.5, H₂O). ¹H NMR (600.13 MHz, D₂O, 25 °C): δ =

3

5.41 (dd, J_1,2= 2.0 Hz, J_P,1-H= 7.7 Hz, 1 H, 1-H), 4.70 (d, J_1Ј,2Ј

= 0.98 Hz, 1 H, 1Ј-H), 4.06 (dd, J_2,3= 3.4 Hz, 1 H, 2-H), 3.93 (dd,

J_2Ј,3Ј= 3.3 Hz, 1 H, 2Ј-H), 3.793 (dd, J_3,4= 9.9 Hz, 1 H, 3-H), 3.790

(dd, J_6Јa,6Јb= –12.3 Hz, 1 H, 6Јa-H), 3.73 (dd, J_6a,6b= –12.4 Hz, 1

H, 6a-H), 3.69 (ddd, J_5,6a= 2.3 Hz, J_5,6b= 5.1 Hz, 1 H, 5-H), 3.67

(dd, 1 H, 6b-H), 3.61 (dd, J_4,5= 10.0 Hz, 1 H, 4-H), 3.60 (dd, 1 H,

1 H, 2Ј-H), 4.05 (dd, J_2ЈЈ,3ЈЈ= 3.2 Hz, 1 H, 2ЈЈ-H), 4.02 (dd, J_2,3

=

3.5 Hz, 1 H, 2-H), 3.863 (dd, J_6Јa,6Јb= –11.7 Hz, 1 H, 6Јa-H), 3.861

(dd, J_{6ЈЈa,6ЈЈb}= –12.0 Hz, 1 H, 6ЈЈa-H), 3.85 (dd, J_6a,6b= –12.2 Hz,

1 H, 6a-H), 3.71 (dd, 1 H, 6Јb-H), 3.67 (dd, 1 H, 6b-H), 3.66 (dd,

1 H, 6ЈЈb-H), 3.54 (dd, J_4Ј,5Ј= 9.7 Hz, 1 H, 4Ј-H), 3.488 (dd, J_3ЈЈ,4ЈЈ

= 9.5 Hz, 1 H, 3ЈЈ-H), 3.487 (dd, J_4ЈЈ,5ЈЈ= 9.5 Hz, 1 H, 4ЈЈ-H), 3.48

(dd, J_3,4= 9.4 Hz, 1 H, 3-H), 3.45 (dd, J_3Ј,4Ј= 9.6 Hz, 1 H, 3Ј-H),

3.43 (dd, J_4,5= 9.4 Hz, 1 H, 4-H), 3.27 (ddd, J_5ЈЈ,6ЈЈa= 2.4 Hz,

6Јb-H), 3.53 (dd, J_3Ј,4Ј= 9.6 Hz, 1 H, 3Ј-H), 3.44 (dd, J_4Ј,5Ј

=

10.0 Hz, 1 H, 4Ј-H), 3.27 (ddd, J_5Ј,6Јa= 2.3 Hz, J_5Ј,6Јb= 6.6 Hz, 1

H, 5Ј-H) ppm. ¹³C NMR (150.90 MHz, D₂O, 25 °C): δ = 98.6 (C-

1Ј), 93.8 (²J_P,C-1= 5.2 Hz, C-1), 77.6 (³J_P,C-2= 8.9 Hz, C-2), 76.3

(C-5Ј), 73.6 (C-5), 72.7 (C-3Ј), 70.7 (C-2Ј), 69.3 (C-3), 66.6 (C-4

and C-4Ј), 60.9 (C-6Ј), 60.4 (C-6) ppm. ³¹P NMR (242.94 MHz,

D₂O, 25 °C): δ = –2.45 ppm. HRMS: calcd. for C₁₂H₂₃NaO₁₄P [M

+ Na]⁺445.0718; found 445.0712.

J_5ЈЈ,6ЈЈb= 6.4 Hz, 1 H, 5ЈЈ-H), 3.21 (ddd, J_5Ј,6Јa= 2.4 Hz, J_5Ј,6Јb

=

6.0 Hz, 1 H, 5Ј-H), 3.20 (ddd, J_5,6a= 2.1 Hz, J_5,6b= 5.1 Hz, 1 H,

5-H) ppm. ¹³C NMR (150.90 MHz, CD₃OD, 20 °C): δ = 102.8 (C-

1Ј), 102.2 (C-1ЈЈ), 95.6 (C-1), 81.4 (C-2), 78.9 (C-2Ј), 78.5 (C-5),

78.3 (C-5Ј and C-5ЈЈ), 75.1 (C-3Ј), 74.5 (C-3ЈЈ), 74.4 (C-3), 72.2 (C-

2ЈЈ), 69.2 (C-4), 68.7 (C-4Ј and C-4ЈЈ), 63.1 (C-6ЈЈ), 62.8 (C-6), 62.5

(C-6Ј) ppm. HRMS: calcd. for C₁₈H₃₂O₁₆Na [M + Na]⁺527.1583;

Methyl β-D-Glucopyranosyl-(1Ǟ2)-α-D-mannopyranoside (55): The

reaction was carried out as outlined in the general procedure for

hydrogenolysis. Compound 54 (40 mg, 0.05 mmol) and Pd/C

(100 mg) in MeOH (4 mL) for 19 h. Yield: 16.5 mg (93%).

[α]_D= +8.5 (c = 1.0, MeOH). ¹H NMR (600.13 MHz, CD₃OD,

25 °C): δ = 4.77 (d, J_1,2= 1.7 Hz, 1 H, 1-H), 4.32 (d, J_1Ј,2Ј= 8.0 Hz,

found 527.1581. HRMS: calcd. for C₁₈H₃₂O₁₆K [M

543.1322; found 543.1317.

+

K]⁺

1 H, 1Ј-H), 3.94 (dd, J_2,3= 3.4 Hz, 1 H, 2-H), 3.85 (dd, J_6Јa,6Јb

–11.8 Hz, 1 H, 6Јa-H), 3.79 (dd, J_6a,6b= –11.9 Hz, 1 H, 6a-H), 3.78

(dd, 1 H, 6b-H), 3.69 (dd, J_3,4= 9.7 Hz, 1 H, 3-H), 3.652 (dd, 1 H,

=

Methyl β-

D-Mannopyranosyl-(1Ǟ2)-β-D-mannopyranosyl-(1Ǟ2)-α-

D-mannopyranoside (42): The reaction was carried out with com-

pound 40 (25 mg, 0.024 mmol) and Pd/C (63 mg) in MeOH

(2.5 mL) for 24 h. Yield: 12 mg (97%). [α]_D= –25.0 (c = 1.0,

MeOH). ¹H NMR (600.13 MHz, CD₃OD, 25 °C): δ = 4.85 (d,

J_1ЈЈ,2ЈЈ= 0.95 Hz, 1 H, 1ЈЈ-H), 4.77 (d, J_1,2= 1.8 Hz, 1 H, 1-H),

4.72 (d, J_1Ј,2Ј= 0.90 Hz, 1 H, 1Ј-H), 4.13 (dd, J_2Ј,3Ј= 3.5 Hz, 1 H,

2Ј-H), 4.07 (dd, J_2ЈЈ,3ЈЈ= 2.9 Hz, 1 H, 2ЈЈ-H), 3.98 (dd, J_2,3= 3.2 Hz,

1 H, 2-H), 3.87 (dd, J_6Јa,6Јb= –11.8 Hz, 1 H, 6Јa-H), 3.86 (dd,

J_{6ЈЈa,6ЈЈb}= –12.0 Hz, 1 H, 6ЈЈa-H), 3.82 (dd, J_6a,6b= –11.9 Hz, 1 H,

6a-H), 3.718 (dd, 1 H, 6b-H), 3.715 (dd, 1 H, 6Јb-H), 3.70 (dd, J_3,4

6Јb-H), 3.651 (dd, J_4,5= 9.6 Hz, 1 H, 4-H), 3.47 (ddd, J_5,6a

=

2.5 Hz, J_5,6b= 4.7 Hz, 1 H, 5-H), 3.38 (s, 3 H, OCH₃), 3.36 (dd,

J_3Ј,4Ј= 9.5 Hz, 1 H, 3Ј-H), 3.30 (dd, J_4Ј,5Ј= 9.0 Hz, 1 H, 4Ј-H),

3.29 (ddd, J_5Ј,6Јa= 2.1 Hz, J_5Ј,6Јb= 5.4 Hz, 1 H, 5Ј-H), 3.25 (dd,

J_2Ј,3Ј= 9.4 Hz, 1 H, 2Ј-H) ppm. ¹³C NMR (150.90 MHz, CD₃OD,

25 °C): δ = 104.1 (C-1Ј), 100.9 (C-1), 79.5 (C-2), 78.2 (C-5Ј), 77.6

(C-3Ј), 74.37 (C-5), 74.35 (C-2Ј), 71.8 (C-3), 71.4 (C-4Ј), 68.6 (C-

4), 62.5 (C-6Ј), 62.1 (C-6), 55.2 (OCH₃) ppm. HRMS: calcd. for

C₃₉H₇₂O₃₃Na [3M + Na]⁺1091.3854; found 1091.3861.

= 9.5 Hz, 1 H, 3-H), 3.68 (dd, 1 H, 6ЈЈb-H), 3.56 (dd, J_4ЈЈ,5ЈЈ

=

9.6 Hz, 1 H, 4ЈЈ-H), 3.55 (dd, J_4Ј,5Ј= 9.6 Hz, 1 H, 4Ј-H), 3.51 (dd,

J_4,5= 9.1 Hz, 1 H, 4-H), 3.49 (dd, J_3ЈЈ,4ЈЈ= 9.6 Hz, 1 H, 3ЈЈ-H),

3.48 (dd, J_3Ј,4Ј= 9.8 Hz, 1 H, 3Ј-H), 3.46 (ddd, J_5,6a= 2.3 Hz, J_5,6b

Methyl β-

D-Glucopyranosyl-(1Ǟ2)-β-D-mannopyranosyl-(1Ǟ2)-α-

D-mannopyranoside (62): The reaction was carried out as outlined

in the general procedure for hydrogenolysis. Compound 61 (50 mg,

0.044 mmol) and Pd/C (125 mg) in MeOH (5 mL) for 24 h. Yield:

21 mg (92%). [α]_D

(600.13 MHz, CD₃OD, 25 °C): δ = 4.78 (d, J_1,2= 1.7 Hz, 1 H, 1-

H), 4.77 (d, J_1Ј,2Ј= 0.71 Hz, 1 H, 1Ј-H), 4.63 (d, J_1ЈЈ,2ЈЈ= 7.7 Hz, 1

= 5.0 Hz, 1 H, 5-H), 3.39 (s, 3 H, OCH₃), 3.24 (ddd, J_5Ј,6Јa

=

2.3 Hz, J_5Ј,6Јb= 5.8 Hz, 1 H, 5Ј-H), 3.23 (ddd, J_5ЈЈ,6ЈЈa= 2.3 Hz,

J_5ЈЈ,6ЈЈb= 6.5 Hz, 1 H, 5ЈЈ-H) ppm. ¹³C NMR (150.90 MHz,

CD₃OD, 25 °C): δ = 102.2 (C-1ЈЈ), 100.8 (C-1Ј), 100.5 (C-1), 79.8

(C-2), 79.3 (C-2Ј), 78.4 (C-5Ј and C-5ЈЈ), 75.1 (C-3ЈЈ), 74.6 (C-5),

74.4 (C-3Ј), 72.1 (C-2ЈЈ), 71.6 (C-3), 69.2 (C-4Ј), 68.6 (C-4), 68.6

(C-4ЈЈ), 63.1 (C-6ЈЈ), 62.5 (C-6), 62.4 (C-6Ј), 55.3 (OCH₃) ppm.

HRMS: calcd. for C₁₉H₃₄O₁₆Na [M + Na]⁺541.1745; found

541.1789.

= –32.0 (c =

1.0, MeOH). ¹H NMR

H, 1ЈЈ-H), 4.10 (dd, J_2Ј,3Ј= 3.3 Hz, 1 H, 2Ј-H), 4.00 (dd, J_2,3

=

3.2 Hz, 1 H, 2-H), 3.85 (dd, J_{6ЈЈa,6ЈЈb}= –11.9 Hz, 1 H, 6ЈЈa-H), 3.824

(dd, J_6a,6b= –11.8 Hz, 1 H, 6a-H), 3.824 (dd, J_6Јa,6Јb= –11.7 Hz, 1

H, 6Јa-H), 3.80 (dd, 1 H, 6Јb-H), 3.76 (dd, J_4,5= 9.9 Hz, 1 H, 4-

H), 3.73 (dd, 1 H, 6b-H), 3.67 (dd, J_3,4= 9.6 Hz, 1 H, 3-H), 3.66

(dd, 1 H, 6ЈЈb-H), 3.62 (dd, J_4Ј,5Ј= 9.5 Hz, 1 H, 4Ј-H), 3.51 (dd,

J_3Ј,4Ј= 9.6 Hz, 1 H, 3Ј-H), 3.46 (ddd, J_5,6a= 2.3 Hz, J_5,6b= 5.1 Hz,

1 H, 5-H), 3.41 (dd, J_3ЈЈ,4ЈЈ= 9.9 Hz, 1 H, 3ЈЈ-H), 3.39 (s, 3 H,

α-D-Mannopyranosyl Phosphate (46): The reaction was carried out

as outlined in the general procedure for hydrogenolysis. Compound

45 (30 mg, 0.042 mmol) and Pd/C (75 mg) in MeOH (3 mL) for

1

20 h. Yield: 10.4 mg (95%). [α]_D= +39.0 (c = 1.0, H₂O). H NMR OCH₃), 3.295 (dd, J_4ЈЈ,5ЈЈ= 9.4 Hz, 1 H, 4ЈЈ-H), 3.288 (ddd, J_5ЈЈ,6ЈЈa

886

www.eurjoc.org

Eur. J. Org. Chem. 2009, 870–888

Synthesis of β-(1Ǟ2)-Linked Oligomannosides

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= 2.0 Hz, J_5ЈЈ,6ЈЈa= 5.4 Hz, 1 H, 5ЈЈ-H), 3.28 (dd, J_2ЈЈ,3Ј= 9.3 Hz,

1 H, 2ЈЈ-H), 3.22 (ddd, J_5Ј,6Јa= 2.2 Hz, J_5Ј,6Јb= 4.5 Hz, 1 H, 5Ј-H)

ppm. ¹³C NMR (150.90 MHz, CD₃OD, 25 °C): δ = 104.8 (C-1ЈЈ),

99.8 (C-1), 99.7 (C-1Ј), 79.3 (C-2Ј), 78.1 (C-2 and C-5Ј), 78.0 (C-

5ЈЈ), 77.7 (C-3ЈЈ), 75.1 (C-2ЈЈ), 74.5 (C-5), 74.0 (C-3Ј), 71.8 (C-3),

71.5 (C-4ЈЈ), 68.7 (C-4), 68.0 (C-4Ј), 62.6 (C-6), 62.5 (C-6ЈЈ), 61.6

(C-6Ј), 55.3 (OCH₃) ppm. HRMS: calcd. for C₁₉H₃₄O₁₆Na [M +

Na]⁺541.1744; found 541.1715.

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Methyl 2-Acetamido-2-deoxy-β-D-glucopyranosyl-(1Ǟ2)-α-D-man-

nopyranoside (59):^[49]The reaction was carried out as outlined in

the general procedure for hydrogenolysis. Compound 58 (36 mg,

0.064 mmol) and Pd/C (72 mg, 2 wt.equiv.) in MeOH (3 mL) for

6 h. Yield: 24 mg (94%). [α]_D= –4.6 (c = 0.77, MeOH); ref.^[49][α]

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²⁰= +2.2 (c = 1.63, H₂O). ¹H NMR (600.13 MHz, CD₃OD, 25 °C):

D

δ = 4.67 (d, J_1,2= 1.7 Hz, 1 H, 1-H), 4.44 (d, J_1Ј,2Ј= 8.4 Hz, 1 H,

1Ј-H), 3.90 (dd, J_2,3= 3.4 Hz, 1 H, 2-H), 3.85 (dd, J_6Јa,6Јb

–12.0 Hz, 1 H, 6Јa-H), 3.83 (dd, J_6a,6b= –11.8 Hz, 6a-H), 3.67 (dd,

1 H, 6Јb-H), 3.65 (dd, J_3,4= 9.6 Hz, 1 H, 3-H), 3.63 (dd, J_2Ј,3Ј

10.1 Hz, 1 H, 2Ј-H), 3.62 (dd, 1 H, 6b-H), 3.50 (dd, J_4,5= 9.8 Hz,

1 H, 4-H), 3.46 (dd, J_4Ј,5Ј= 10.4 Hz, 1 H, 4Ј-H), 3.45 (ddd, J_5,6a

2.3 Hz, J_5,6b= 6.6 Hz, 1 H, 5-H), 3.38 (s, 3 H, OCH₃), 3.32 (dd,

J_3Ј,4Ј= 8.7 Hz, 1 H, 3Ј-H), 3.27 (ddd, J_5Ј,6Јa= 2.3 Hz, J_5Ј,6Јb

=

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5.7 Hz, 1 H, 5Ј-H), 2.00 (s, 3 H, NHC=OCH₃) ppm. ¹³C NMR

(150.90 MHz, CD₃OD, 25 °C): δ = 174.4 (NHC=OCH₃), 101.7 (C-

1Ј), 99.9 (C-1), 78.8 (C-2), 78.1 (C-5Ј), 75.4 (C-4Ј), 74.8 (C-5), 72.0

(C-3Ј), 71.7 (C-3), 69.1 (C-4), 63.4 (C-6), 62.6 (C-6Ј), 57.3 (C-2Ј),

55.3 (OCH₃), 23.3 (NHC=OCH₃) ppm. HRMS: calcd. for

C₁₅H₂₇NO₁₁Na [M + Na]⁺420.1476; found 420.1456.

Supporting Information (see footnote on the first page of this arti-

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Acknowledgments

Financial support from the Finnish Funding Agency for Technol-

ogy and Innovation, TEKES (project 40134/06 for R.L. and

Johannes Savolainen), the Academy of Finland (projects #121335

and 122126 for R. L. and Johannes Savolainen), Magnus

Ehrnrooth Foundation (M.U.R.), and the National Glycoscience

Graduate School (T.S.) is gratefully acknowledged. The authors

thank Markku Reunanen and Päivi Pennanen for technical assist-

ance with HRMS and NMR analyses, respectively. We also thank

Dr. Johannes Savolainen and Kaisa Nieminen (University of

Turku) for helpful discussions and collaboration, Dr. Jari Helin

(Glykos Finland) for assistance with the mannobiose purification,

and Dr. Agnieszka J. Pawlowicz for assistance with the HPLC puri-

fications and product analyses.

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Published Online: January 8, 2009

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Article Doi

Synthesis of |β-(1→2)-linked oligomannosides

DOI: 10.1002/ejoc.200801024

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Article abstract of DOI:10.1002/ejoc.200801024

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