Synthesis and acid catalyzed hydrolysis of B2,5 type conformationally constrained glucopyranosides: Incorporation into a cellobiose analogue

Tetrahedron 60 (2004) 6813–6828

Synthesis and acid catalyzed hydrolysis of B_2,5type

conformationally constrained glucopyranosides:

incorporation into a cellobiose analogue

a

Yves Bleriot, Subramanian K. Vadivel, Antonio J. Herrera, Ian R. Greig, Anthony J. Kirby

a

b

,

*

´

and Pierre Sinay¨^a

,

*

a

´ ´ ´

Departement de Chimie, Ecole Normale Superieure, UMR 8642 associee au CNRS, 24 rue Lhomond, 75231 Paris Cedex 05, France

^bUniversity Chemical Laboratory, Cambridge CB2 1EW, UK

Accepted 3 June 2004

Abstract—Isopropyl and p-nitrophenyl a- and b-D-glucopyranosides, restrained in a conformation close to B_2,5via an oxymethylene bridge

have been synthesized. These four glucopyranosides were found to be hydrolyzed at similar rates, close to those observed for the parent

unconstrained glucosides. In such derivatives, either a or b, the exocyclic cleaved bond is synperiplanar to an endocyclic oxygen lone pair.

This conformationally locked glucopyranosyl moiety was also incorporated into a disaccharide, affording a conformationally restrained

cellobiose analogue which was assayed against various glycosidases.

1. Introduction

studied reaction with a well-established mechanism

involving a speciﬁc acid catalysis, the rate determining

step being the formation of a cyclic alkoxycarbenium ion

intermediate (Scheme 1).³

Oligo- and polysaccharides, the most abundant bio-

molecules on earth, are made of monosaccharide monomers

connected together through a glycosidic linkage. This bond,

which is formed or cleaved during bioprocesses is thus

inherently critical for the emergence of the numerous

biological properties of this class of compounds. As a

consequence, an in-depth understanding of the mechanism

of glycosidic bond cleavage is essential.

Nevertheless, some features of this reaction have yet to be

fully explored to quantify the effects, which control

reactivity in glycosyl transfer. Bols and co-workers have

demonstrated that steric effects are not the cause of the rate

difference observed during hydrolysis of stereoisomeric

glycopyranosides⁴ruling out long-standing Edward’s pro-

posal.⁵They rather suggested that the rate difference can be

attributed to the different electron-withdrawing effects of

axially and equatorially oriented hydroxyl groups involved

in the destabilization of the transient cyclic alkoxy-

carbenium ion. These ﬁndings are in agreement with

Withers results invoking a Kirkwood–Westheimer model

of ﬁeld effects to explain the opposite effect on the

An increasing number of articles dissecting the enzymatic

cleavage of the glycosidic bond by glycosidases have

appeared recently, taking advantage of kinetic studies and

protein crystallography,¹but few recent papers are indeed

dealing with the non-enzymatic hydrolysis of glycosides:²

the same set of pioneering articles is usually cited. The

chemical hydrolysis of glycopyranosides is indeed a much-

Scheme 1. A mechanism for the chemical hydrolysis of alkyl glycopyranosides, involving the protonation of the exocyclic oxygen atom.

Keywords: Carbohydrates; Cellobiose; Conformation; Glycosidase; Hydrolysis.

*

Corresponding authors. Tel.: þ44-1223-336370; fax: þ44-1223-336913 (A.J.K.); tel.: þ33-1-44323390; fax: þ33-1-44323397 (P.S.);

e-mail addresses: ajk1@cam.ac.uk; pierre.sinay@ens.fr

doi:10.1016/j.tet.2004.06.009

´

Y. Bleriot et al. / Tetrahedron 60 (2004) 6813–6828

6814

hydrolysis rates of glycopyranosides of the deoxygenation

of hydroxyl groups and their replacement by ﬂuorine.⁶

Furthermore, the contribution of torsional effects on

reactivity in glycosyl transfer has a signiﬁcant albeit not

large effect on the rate of hydrolysis of glycopyranosides.⁷

conformations (Fig. 2) are possible candidates for the

conformation of the glycopyranosyl oxycarbenium ion,

wherein the four atoms C-5, O-5, C-1 and C-2 become

coplanar as the anomeric center is rehybridized from sp³

to sp². An increasing number of these boat type confor-

mations have recently been convincingly observed in nature

for some glycosidases that distort the substrate away

The conformational aspects of the chemical hydrolysis of

glycopyranosides have been less explored due to the short

lifetime of the transient cyclic alkoxycarbenium and the

difﬁculty of probing the conformation of this intermediate.⁸

Bennet and Sinnott, using kinetic isotopic effects, have

studied the acid-catalyzed hydrolysis of methyl ^D-gluco-

pyranosides,⁹and concluded that methyl a-D-glucopyrano-

side was hydrolyzed via a skew or boat conformation

whereas the b-anomer reacted through a chair-like confor-

mation. Similar conclusions were drawn with xylopyrano-

sides.¹⁰We disclose here another approach to generating the

conformation adopted by the cyclic alkoxycarbenium and/or

the glucopyranoside at the point of hydrolysis: locking the

structure of the glycopyranoside in a deﬁned conformation

and a subsequent analysis of its behavior towards acid-

catalyzed hydrolysis should tell us if this conformation can

be operative during oxycarbenium formation.¹¹A careful

study is necessary because conformational restraints

have been shown to have signiﬁcant effects on the reactivity

of tetrahydropyranyl acetals.¹²

4

from the ground state C₁conformation before enzymatic

hydrolysis.¹⁵

If the conformation adopted by the sugar prior to oxygen–

carbon bond cleavage is indeed B_2,5(or ^2,5B), this implies

that the antiperiplanar lone pair effect (ALPE)¹⁶is not

operating in the hydrolytic process. Such a cleavage would

rather be compatible with synperiplanar assistance, known

to be effective in the hydrolysis of constrained tetrahydro-

pyranyl acetals,¹⁷and consistent with the relevant least

nuclear motion effect.¹⁸

2. Results

In this context, we report the synthesis of p-nitrophenyl and

isopropyl a- and b-^D-glucopyranosides locked in a B_2,5

conformation and on their rates of hydrolysis under acidic

conditions. The selected constrained targets are 1–4, carbon

atoms 2 and 5 linked via an oxymethylene bridge.¹⁹We also

envisioned an oxycarbonyl linkage to lock the conformation

as in compound 5 (Fig. 3). The choice of both isopropyl

and p-nitrophenyl glycosides is designed to detect the

possibility of endocyclic cleavage, which is always a

potential complication, particularly in the acid-catalysed

hydrolysis of conformationally restricted glycosides. Com-

parison of kinetics for these compounds will enable us to tell

whether this mechanism is operative because the endocyclic

pathway for the hydrolysis of nitrophenyl glycosides

would be orders of magnitude slower than for isopropyl

derivatives.

Whatever the exact mechanism of glycoside hydrolysis,

nucleophilic substitution at the glycosidic bond involves

the sugar becoming either an oxycarbenium ion inter-

mediate or passing through a transition state that is highly

oxycarbenium ion-like.

Considering the complete map of pyranoid ring inter-

conversions (Fig. 1), including the boat/skew-boat pseudo-

rotational itinerary of the pyranoid ring,¹³and as suggested

4

3

previously,¹⁴not only H₃and H₄, but also B_2,5and ^2,5B

Compounds 1–5 are conﬁned for stringent geometrical

reasons to the following conformational domain of the boat/

skew boat itinerary close to B_2,5

:

3. Results and discussion

3.1. Chemical synthesis

The strategy used to synthesize compounds 1–5 starts

from the known vinyl derivative 6.²⁰It was ﬁrst converted

Figure 1. Partial map of pyranoside ring interconversions (adapted from

Stoddart).¹³

Figure 2. Possible conformations for a glycopyranosyl oxycarbenium ion. Hydroxyl groups have been omitted for the sake of clarity. Coplanar atoms are

indicated with asterisks (adapted from Berti and Tanaka).¹⁴

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Y. Bleriot et al. / Tetrahedron 60 (2004) 6813–6828

6815

Figure 3. Structure of the conformationally constrained a- and b-D-glucopyranosides 1–5, showing the syn-periplanarity of one pyranoside orbital of the

intracyclic oxygen and of the glycosidic bond.

Scheme 2. Synthesis of the glycosyl donor 11. Reagents and conditions: (a) IR-120 H^þresin, dioxan, H₂O, 90 8C; (b) Ac₂O, DMAP, pyridine, rt; (c) PhSH,

BF₃·OEt₂, anhydrous CH₂Cl₂, rt; (d) CH₃ONa, CH₃OH, rt; (e) PhCH(OMe)₂, CSA, DMF, rt; (f) O₃, CH₂Cl₂, 278 8C; (g) NaBH₄, EtOH, rt; (h) TsCl, DMAP,

pyridine, rt; (i) NaH, DMF, rt.

into the conformationally restrained glycosyl donor 11

(Scheme 2).

yield (91%) and in a 1:4 ratio. Treatment of glucoside 12

with sodium bromate and sodium dithionite in ethyl acetate/

water²¹simultaneously performed the opening of the

benzylidene acetal and the cleavage of the benzyl ether to

afford a mixture of the 4-O-benzoyl derivative 14 and the

6-O-benzoyl derivative 15 in 68% yield. Deprotection of the

benzoate 14 and 15 with sodium methoxide in methanol

afforded the p-nitrophenyl b-^D-glucoside 1 in 73% yield.

Treatment of compound 6 under acidic conditions afforded

the corresponding glucopyranose derivative, which was

isolated in 76% yield as the peracetylated derivative 7.

Reaction of 7 with PhSH and BF₃·OEt₂in dry dichloro-

methane gave the thiophenyl derivative 8 in 84% yield.

Deacetylation of 8 was followed by the easy formation of

alcohol 9. Careful ozonolysis of compound 9, in order to

avoid sulfur oxidation, led to the corresponding aldehyde

which was not isolated and directly reduced to the alcohol

using sodium borohydride in ethanol to give diol 10 in 62%

yield from the thiophenyl glycoside 8. Subsequent tosyla-

tion of the ‘neopentylic’ alcohol of diol 10, followed by

treatment with NaH in DMF led to cyclisation, affording the

glycopyranosyl donor 11 in 88% yield. Compound 11

constitutes a novel conformationally locked glucopyranosyl

donor, which was now used to obtain the conformationally

locked glycosides 1, 2 and 3 (Scheme 3).

The same sequence was uneventfully applied to compound

13 to afford the p-nitrophenyl a-^D-glucoside 2 in 84%

overall yield.

Compound 3 was also obtained from glycosyl donor 11.

Its treatment with dry isopropanol in the presence of

N-chlorosuccinimide (NCS) gave the protected isopropyl

a-^D-glucoside 18 along with traces of the corresponding

protected b-^D-glucoside. Surprisingly, hydrogenolysis of

18 under various conditions only led to decompo-

sition products. Fortunately, reduction with Na-liq. NH₃

afforded the pure a-D-glucoside 3 after careful column

chromatography.

When compound 11 was treated with para-nitrophenol in

the presence of N-iodosuccinimide (NIS) and triﬂic acid in

dichloromethane, the para-nitrophenyl b-^D-glucopyrano-

side 12 and a-^D-glucopyranoside 13 were obtained in high

Compounds 4 and 5 were now synthesized from the iso-

propyl b-^D-glucopyranoside 19, obtained by glycosylation

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Y. Bleriot et al. / Tetrahedron 60 (2004) 6813–6828

6816

Scheme 3. Synthesis of compounds 1, 2 and 3. Reagents and conditions: (a) para-nitrophenol, NIS, TfOH, CH₂Cl₂, 230 8C; (b) NaBrO₃, Na₂S₂O₄, EtOAc,

H₂O, rt; (c) CH₃ONa, CH₃OH, rt; (d) NCS, dry isopropanol, rt; (e) Na, liq. NH₃.

in 76% yield from the acetate 7 using anhydrous

isopropanol and TMSOTf (Scheme 4). An unevent series

of reactions similar to that previously described led to the

target 4.

then fully protected using isopropylidene acetal and tert-

butyldimethylsilyl protecting groups to give compound 23.

Prolonged ozonolysis of the CvC bond yielded the

corresponding carboxylic acid which was not isolated and

directly converted to its methyl ester 24 using iodomethane

and KHCO₃in DMF. Selective removal of the silyl

protection group with TBAF gave the corresponding

The lactone 5 was obtained in eight steps from isopropyl

b-^D-glucopyranoside 19 which was ﬁrst deacetylated and

Scheme 4. Synthesis of compounds 4 and 5. Reagents and conditions: (a) TMSOTf, dry isopropanol, rt; (b) CH₃ONa, CH₃OH, rt; (c) PhCH(OMe)₂, CSA,

DMF, rt; (d) O₃, CH₂Cl₂, 278 8C; (e) NaBH₄, EtOH, rt; (f) TsCl, DMAP, pyridine, rt; (g) NaH, DMF, rt; (h) H₂, Pd/C, CH₃OH, rt; (i) Me₂CH(OMe)₂, CSA,

DMF, rt; (j) TBDMSCl, imidazole, DMF, 60 8C; (k) O₃, CH₂Cl₂, 278 8C; (l) MeI, KHCO₃, DMF, rt; (m) TBAF, THF, rt; (n) 60% aq. AcOH, 60 8C; (e) H₂, Pd/

C, CH₃OH, rt.

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Y. Bleriot et al. / Tetrahedron 60 (2004) 6813–6828

6817

Figure 4. Crystallographic structure of compounds 2 and 5.

alcoholate with spontaneously lactonized, affording the

fully protected d-lactone 25. Final deprotection using aq.

AcOH followed by hydrogenolysis furnished compound 5

as a crystalline compound. Compound 5 is interesting

regarding human a-^L-iduronidase, a family 39 glycosidase

supposed to distort its substrate in a ^2,5B conformation with

a possible neighboring group participation of the carb-

oxylate.²²Lactone 5 could thus mimick the conformation-

ally locked intermediate suggested by Withers.

and 5, which were crystalline, and for which X-ray

structures have been solved (Fig. 4).^11,24

Finally, the conformationally restrained glycosyl donor 11

was used to obtain a cellobiose analogue containing a

monosaccharide unit locked in B_2,5conformation. Reaction

of thiophenyl glucoside 11 with the known methyl 2,3,6-tri-

O-benzyl-a-^D-glucopyranoside²⁵26 in the presence of NIS,

˚

triﬂic acid and 4 A molecular sieves in dry dichloromethane

afforded exclusively the b linked fully protected disac-

charide 27. This selectivity can be explained by the

¹H NMR of compounds 1–5 indicated that they adopted in

23

`

steric hindrance created by the oxymethylene bridge vis a

vis the bulky glycosyl acceptor. Hydrogenolysis of the

solution a conformation close to B_2,5

mation was also observed in the solid state for compounds 2

.

This boat confor-

˚

Scheme 5. Synthesis of disaccharide 28. Reagents and conditions: (a) NIS, 4 A molecular sieves, dry dichloromethane, 240 8C; (b) H₂, Pd/C, CH₃OH, rt.

Table 1. Hydrolysis of p-nitrophenyl compounds^a

10⁴k_obs/s²¹

k_rel(70 8C)

2.6^0.02

1.0

116^8

24^23

3.20^0.6

1.23

108^3

2.4^10

2.27^0.2

0.87

96.2^1.4

235^42

0.35^0.01^b

0.13⁵

110^12

28^34

DH^‡/kJ mol²¹

DS^‡/J K²¹mol²¹

a

Notes. Data collected at three temperatures in the ranges 60–70 8C, in 1 M aqueous HCl. Rate constants quoted are for 70 8C (full data appear in Table 3

below). Rates and thermodynamic parameters for the parent glucosides are consistent with previous measurements.

Data collected at three temperatures in the ranges 70–80 8C, in 1 M aqueous HCl.

b

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Y. Bleriot et al. / Tetrahedron 60 (2004) 6813–6828

6818

Table 2. Hydrolysis of isopropyl compounds^a

10⁴k_obs/s²¹

k_rel(80 8C)

6.9^0.4

1.0

3 (1)

4.2^1.1

0.61

4 (2)

2.3^0.5

0.33

5 (2)

1.6^0.1

0.23

2 (1)

No. signals followed^b

a

Notes. Reactions followed by ¹H NMR at 80 8C, in 1 M aqueous DCl/D₂O. For solubility reasons the solvent D₂O contained 10% of dioxan-d₈for the

reactions of the constrained compounds (3 and 4). Rate constants for the parent glucosides are consistent with previous measurements.

Number of readily discernable peaks followed to stable end point (see the text).

b

benzyl groups yielded the cellobiose analogue 28

(Scheme 5).

reactant, reduces reactivity scarcely at all for either

p-nitrophenyl system 1 or 2: and by factors of only 2 and

3 for the isopropyl derivatives 3 and 4. In each case the

differences are smaller than the well-known differences in

reactivity between the anomers of the parent unconstrained

glucosides. Apparently the synperiplanar lone pairs of

these constrained compounds stabilize the developing

oxocarbenium ion character in the transition state for acid

catalyzed cleavage about as effectively as the antiperiplanar

lone pairs of the unconstrained a-glucosides. In the case of

the tetrahydropyranyl system 29 (R¼Ar) (Fig. 5) it was

concluded, on the basis of a crystal structure correlation

(see below), that the synperiplanar n_O-s^p_C–ORinteraction is

somewhat weaker in the reactant ground state, and that at

least part of its observed reactivity must derive from the

higher ground state energy of the boat conformation.

3.2. Reactivity of the constrained glycosides

We report rates of acid-catalyzed hydrolysis for the four

conformationally constrained compounds 1–4 under

standard conditions (1 M HCl, ionic strength 1.0 M). For

comparison we have measured also the rates of hydrolysis of

the corresponding unconstrained glucosides, p-nitrophenyl

and isopropyl a- and b-glucopyranosides,²⁶under the same

conditions. Results appear in Tables 1 and 2.²⁷The reactions

of the p-nitrophenyl derivatives were studied over a range of

temperatures and HCl concentrations, providing second

order rate constants for acid catalysis and thermodynamic

parameters for the hydrolysis reactions (see Section 5,

Table 3). Table 1 compares ﬁrst order rate constants in 1 M

HCl (identical to the second order rate constants) at 70 8C

for the p-nitrophenyl compounds. The hydrolyses of the

1

isopropyl compounds were followed by H NMR, in 10%

dioxan-d₈—D₂O in 1 M DCl at 80 8C. Thus internal

comparisons, for the p-nitrophenyl compounds (Table 1)

and the isopropyl derivatives (Table 2) are for identical

conditions, but comparisons between the tables are not.

However, the differences are expected to be small: the

solvent deuterium isotope effect, of the order of 2 for the acid

catalyzed hydrolysis of alkyl glycosides, slows the reactions

of the isopropyl compounds by this factor, partly compen-

sating for the higher temperature (a factor of the order of 3

for 10 8C, according to the thermodynamic parameters of

Table 1). The solvent effect of 10% dioxan is considered

negligible.

Figure 5. Structure of compounds 2 and 29.

Though both a- and b-constrained compounds possess

similar synperiplanar lone pair/leaving group n_O-s_C^p_–OR

interactions in their ground states the rates of hydrolysis

of the a-constrained compounds are higher than those of the

b-constrained compounds, by 41 and 83%, respectively, for

the p-nitrophenyl and isopropyl compounds. It is unlikely

that these small effects have a simple, single explanation.

Possible contributions from the different patterns of

functionalities surrounding the glycosidic center are the

enhanced b-effect of the C(2)–O of the C(6)–O bridge,

which is antiperiplanar to the bond to the leaving group in

the b-anomers, and internal hydrogen-bonding between the

C(3)–OH and the incoming water nucleophile (similar to

that suggested by Sinnott and Jencks to explain differences

in reactivity to solvolysis of a- and b-glucopyranosyl

ﬂuorides).²⁸

Table 3. Second order rate constants for the acid-catalysed hydrolysis of

p-nitrophenyl glycosides, in 0.8–1.0 M HCl and ionic strength 1.0

Compound

k

_Hþ£10⁵/dm³mol²¹s²¹at temperature (in 8C) given below

60

65

70

75

80

a-pNP-Glu

2 a-constr

1 b-constr

b-pNP-Glu

6.7^0.4 13.7^1.0 26.0^2.0

10.0^0.9 18.6^1.5 32.0^3.6

8.0^0.5 11.9^3.2 22.7^2.9

3.5^0.2 5.6^0.4 10.9^0.7

3.3. Ground state effects

The clear conclusion from the results summarized in

Tables 1 and 2 is that compounds 1–4 are hydrolyzed at

rates similar to those of the corresponding unconstrained

a-glucosides. The severe conformational constraint

imposed by the [2,2,2] bicyclic system, which excludes a

signiﬁcant antiperiplanar n_O-s^p_{C –OR}interaction in the

Bond length (x)—leaving group (pK_aof ROH) correlations

for the series of tetrahydropyranyl acetals 29 (R¼Ar),

constrained in the symmetrical boat conformation by the

3-carbon bridge, are consistent with a substantial ground

state n_O-s^p_C–ORinteraction, though one which is weaker in

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Y. Bleriot et al. / Tetrahedron 60 (2004) 6813–6828

6819

the synperiplanar than in the antiperiplanar geometry¹⁷

(observed bond-length changes are considered a ‘more or

less uncomplicated measure of stereoelectronic effects’ in

this system). However, the rates of (spontaneous) hydrolysis

are signiﬁcantly more sensitive to the leaving group for

the constrained system. The rate of acid catalyzed

hydrolysis of the methyl acetal (29, R¼Me) is similar to

that of 2-methoxytetrahydropyran (corresponding confor-

mationally to an a-glucoside), as observed for the isopropyl

derivative 4 described in this paper.

Disaccharide 28, displaying a distorted B_2,5glucose unit,

was only found to inhibit weakly Cel7B (K_i3.4 mM) and

did not inhibit nor was cleaved by Cel6A and Cel7A. The

limited size of disaccharide 28 makes it unable to span in

the important 22, 21, þ1 and þ2 subsites of the active site

and is probably responsible for its lack of inhibition.³⁵

These results could also be rationalized by a possible steric

clash between the nucleophile in the active site and the

bridge present in the disaccharide.

Of the present series of compounds we have a crystal

structure only for the constrained a-p-nitrophenyl derivative

2 (Fig. 4). The data are not of high accuracy, and

conclusions based on a single structure must be very

tentative. However, the pattern of bond lengths at the

anomeric center is consistent with the operation of

substantial (and comparable) n_O-s^p_C–ORinteractions in 2

and in the corresponding a-^D-glucopyranoside, but little

or none in the case of the b-^D-glucopyranoside. Thus

the length of the exocyclic C–O bond x at the acetal center

4. Conclusion

We have synthesized ﬁve monosaccharides 1–5 locked in

a B_2,5conformation. Compounds 1–4 were hydrolyzed

in acid at similar rates, close to those reported for the

corresponding unlocked glucosides. This conﬁrms that B_2,5

transient conformations of glycosides can indeed be

acceptable candidates for direct acid hydrolysis, despite

the fact that ALPE is not operating. Incorporation of this

glucosyl unit into a disaccharide 28 yielded a cellobiose

analogue which displayed only weak inhibition of cellobio-

hydrolases and barley b-^D-glucan glucohydrolase. Never-

theless, these new glucosyl scaffolds adopting a boat

conformation are interesting candidates to probe glycosi-

dases that distort their substrate towards a B_2,5conformation

during or prior to hydrolysis. This is in keeping with the

design of an increasing number of inhibitors adopting a boat

conformation.³⁶Furthermore, inhibitory results for several

inhibitors have now been rationalized by invoking such a

boat conformation.³⁷

˚

is 1.413(8) A in 2, the same as observed for p-nitrophenyl

a-^D-glucopyranoside (1.415(3) A²⁹and signiﬁcantly greater

˚

than the value of 1.404 A (based on the good bond length-

leaving group correlation established for a series of

b-^D-glucopyranosides)²⁹expected for the corresponding

bond in p-nitrophenyl b-^D-glucopyranoside.

3.4. Glycosidase inhibition

Cellobiose analogue 28 was ﬁrst assayed against a variety

of commercially available glycosidases. Compound 28

did not show inhibition at

a

concentration of

0.2 mmol mL²¹on yeast a-glucosidase, almond b-gluco-

sidase, Jack bean a-mannosidase, green coffee bean

a-galactosidase, bovine liver a-galactosidase, bovine

kidney b-N-acetylglucosaminidase, Penicillium decumbens

naringinase, Aspergillus niger amyloglucosidase and human

placenta a-^L-fucosidase. We then investigated the inhibition

of compound 28 on barley b-^D-glucan glucohydrolase, a

family GH3 glycoside hydrolase that catalyses hydrolytic

removal of non-reducing glucosyl residues from b-^D-

glucans.³⁰We expected compound 28 to ﬁt in the two 21

and þ1 subsite-binding sites of this glycosidase recently

proved to perform substrate distortion.³¹Disaccharide 28

was found to be a weak competitive inhibitor (K_i16.1 mM)

of this enzyme, probably because this glycosidase does not

perform a substrate distorsion toward a B_2,5conformation

but rather a ⁴H₃conformation as suggested by the very tight

5. Experimental

5.1. Kinetics of hydrolysis

The hydrolyses of the p-nitrophenyl glucosides and the

constrained compounds 1 and 2 were followed spectro-

photometrically 348.6 nm, the wavelength of maximum

change in absorbance for the hydrolysis of p-nitrophenyl

glucosides to p-nitrophenol occurs. Stock solutions (con-

taining approximately 6 mg mL²¹) were prepared in water

(p-nitrophenyl glucosides) and 20% v/v 1,4-dioxane/water

(for constrained compounds 1 and 2, which are insoluble in

pure water). ‘Constant pH’ solutions 1.0, 0.9 and 0.8 M in

hydrochloric acid were made from Convol^wstock solutions

and their ionic strength adjusted to a value of 1.0 M (where

necessary) by the addition of an appropriate volume of

2.0 M potassium chloride solution. For kinetic runs aliquots

(20 or 60 mL) were injected into 2.4 mL volumes of the

constant pH solutions, to give ﬁnal 1,4-dioxane concen-

trations ,0.5% v/v in the case of the constrained

compounds. Reactions were followed over a range of

temperatures for each glycoside and pseudo-ﬁrst-order rate

constants (k_obs, Table 3) obtained by non-linear least squares

ﬁtting of A_348.6vs. time data to a standard ﬁrst order

equation. Derived second order rate constants are given in

Table 3.

4

binding of a glucophenylimidazole adopting a H₃confor-

mation.³¹Finally, compound 28 was tested against Cel6A,

Cel7A and Cel7B cellobiohydrolases from Trichoderma

Reesei,³²which degrade crystalline cellulose very efﬁ-

ciently, releasing cellobiose from one or the other chain end.

Vasella et al. showed that glycosidase inhibitors based on a

lactone motif and adopting a half-chair conformation

happened to be weak inhibitors of these enzymes, their

shape being probably not complementary to the 21 subsite

of these cellulases.³³This is in keeping with the distorsion

of the glucosyl unit in the 21 subsite towards a skew-boat

conformation observed in the crystal structure of one of

the members of the family-7 glycosidases, EGI of Fusarium

oxysporum, in complex with a thioglucoside.³⁴

The isopropyl glucosides and the constrained compounds 3

and 4 do not contain strong chromophores, and their acid

catalyzed hydrolysis reactions cannot be followed by UV

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Y. Bleriot et al. / Tetrahedron 60 (2004) 6813–6828

6820

spectroscopy. The hydrolysis of alkyl glycosides is most

often followed by polarimetry, observing a change in optical

rotation of with time. Choice of a suitable wavelength, at

which a large change in speciﬁc rotation occurs over the

water (200 mL). Ion exchange resin IR-120 (20 g) was

added and the solution was stirred for 18 h at 90 8C.

The reaction mixture was cooled to rt and the resin was

ﬁltered, washed with water (100 mL). The solvent was

evaporated and the residue was dried on a vacuum pump

to afford the crude tetrol, which was directly used for the

next step. Crude tetrol was dissolved in dry pyridine

(100 mL) under argon and the solution cooled to 0 8C.

Acetic anhydride (30 mL) and DMAP (50 mg) were added

and the reaction mixture was stirred for 15 h at rt. The

solvent was removed under reduced pressure and the residue

co-evaporated with toluene (2£50 mL). Puriﬁcation by

column chromatography (EtOAc/cyclohexane 1:4!1:3)

afforded compound 7 (11.5 g, 0.025 mol, 76%) as a

crystalline solid.

course of a reaction, allows relatively low (mg mL²¹

)

concentrations of glycosides to be used. Compounds 3 and 4

were available in only small quantities, but a variable

wavelength polarimeter was not available. So the rates of

acid catalyzed hydrolysis of the isopropyl glycosides and

1

their hydrolyses were followed by H NMR. This method

also required relatively large amounts of material (ca. 30 mg

per kinetic run), so a maximum of two runs could be carried

out for each compound. Reactions were followed in 1 M

DCl in D₂O (containing 10% 1,4-dioxane-d₈for the

constrained compounds), so the rates of reaction obtained

are not exactly comparable with those of the p-nitro-

phenylglucosides (obtained in protic media): though the

opposite effects of the solvent deuterium isotope effect and

the 10 8C difference in temperature partly cancel out.

[a]²_D²¼273 (c¼1 in CHCl₃); mp 111 8C (ethyl acetate/

n-pentane); ¹H NMR (CDCl₃, 400 MHz): d¼7.37–7.25 (m,

5H, Ph), 5.98–5.89 (m, 3H, H-1, H-7, H-8), 5.67 (dd, J¼3.0,

9.2 Hz, 1H, H-8⁰), 5.46 (d, J¼10.1 Hz, 1H, H-4), 5.26 (dd,

J¼8.4, 9.6 Hz, 1H, H-2), 4.63 (s, 2H, CH₂Ph), 4.18 (d,

J¼12.5 Hz, 1H, H-6), 3.76 (t, J¼9.8 Hz, 1H, H-3), 3.72 (d,

J¼12.5 Hz, 1H, H-6⁰), 2.21 (s, 3H, OAc), 2.15 (s, 3H, OAc),

2.14 (s, 3H, OAc); ¹³C NMR (CDCl₃, 100 MHz): d¼

170.61, 169.44, 168.97, 168.90, (4£CvO), 137.56 (Cipso),

129.66 (CH-7), 128.41, 127.82, 127.56 (Ph), 121.98

(CH₂-8), 88.67 (CH-1), 78.36 (C-5), 77.83 (CH-3), 74.54

(CH₂Ph), 72.44 (CH-2), 69.28 (CH-4), 64.99 (CH₂-6),

20.85, 20.78, 20.69, 20.62 (4£OAc); MS (CI, NH₃): m/z

(%): 482 (100) [MþNH₄^þ]; elemental analysis: calcd (%)

for C₂₃H₂₈O₁₀(464.47): C 59.47, H 6.07; found C 59.59, H

6.17.

The ¹H NMR spectra obtained for these hydrolysis

experiments were less than ideal for the purpose. Peaks

that could be readily assigned to starting material or product

were often not well resolved, and in such cases it was not

possible to derive kinetic data from changes in integrated

peak areas. However, the reactions of the isopropyl-

glucosides could be followed by observing the variation in

chemical shift for a number of protons in the spectra. The

data obtained in this way are shown in Table 4.

Table 4. Rate constants for the hydrolysis of isopropyl glycosides, in 1 M

HCl at 80 8C and ionic strength 1.0^a

Compound

k

_Dþ£10⁵/M²¹s²¹at 80 8C

No. of peaks followed

(no. of runs carried out)

5.2.2. Phenyl 2,4,6-tri-O-acetyl-3-O-benzyl-5-C-vinyl-1-

7 (11.5 g,

thio-b-^D-glucopyranoside 8. Tetraacetate

0.025 mol) was dissolved in dry CH₂Cl₂(150 mL) and the

solution cooled to 0 8C. Thiophenol (3.1 mL) was added

dropwise followed by BF₃·OEt₂(9.35 mL) and the reaction

mixture was stirred at rt. After 10 h, the reaction mixture

was diluted with CH₂Cl₂(150 mL), washed with saturated

aq. NaHCO₃(150 mL) and water (150 mL). Organic

extracts were dried over MgSO₄and concentrated. Puriﬁ-

cation by column chromatography (EtOAc/cyclohexane

a-i-Pr-Glu

4 a-constr

3 b-constr

b-i-Pr-Glu

69^4

46^17

23^5

16^1

3 (1)

4 (2)

5 (2)

2 (1)

a

Notes. Rates followed by ¹H NMR (see the text).

5.2. General methods

1:4) afforded the thiophenyl derivative

0.021 mol, 84% yield) as an oil.

8 (10.83 g,

Melting points were determined with a Bu¨chi model 535 mp

apparatus and are uncorrected. Optical rotations were

measured at 20^2 8C with a Perkin Elmer Model 241

digital polarimeter, using a 10 cm, 1 mL cell. Chemical

Ionisation Mass Spectra (CI-MS ammonia) and Fast Atom

Bombardment Mass Spectra (FAB-MS) were obtained with

a JMS-700 spectrometer. Elemental analyses were per-

1

[a]²_D⁰¼264 (c¼1 in CHCl₃); H NMR (CDCl₃, 400 MHz):

d¼7.63–7.23 (m, 10H, 2£Ph), 5.91 (dd, J¼11.2, 17.8 Hz,

1H, H-7), 5.49 (d, J¼11.2 Hz, 1H, H-8), 5.36 (d, J¼

10.2 Hz, 1H, H-1), 5.26 (dd, J¼0.9, 17.8 Hz, 1H, H-8⁰), 5.07

(dd, J¼9.3, 10.1 Hz, 1H, H-3), 4.85 (d, J¼10.1 Hz, 1H,

H-4), 4.62 (d, J¼11.6 Hz, 1H, CH₂Ph), 4.56 (d, J¼11.6 Hz,

1H, CH₂Ph), 4.09 (d, J¼12.2 Hz, 1H, H-6), 3.84 (d, J¼

12.2 Hz, 1H, H-6⁰), 3.72 (dd, J¼9.4, 10.1 Hz, 1H, H-2),

2.12, 2.06, 1.99 (3£s, 9H, 3£OAc); ¹³C NMR (CDCl₃,

100 MHz): d¼170.70, 169.02, 168.91 (3£CvO), 137.70,

130.86 (2£Cipso), 134.82, 128.65, 128.40, 127.77, 127.58

(Ph), 130.62 (CH-7), 121.62 (CH₂-8), 80.88 (CH-4), 79.42

(C-5), 79.17 (CH-2), 74.54 (CH₂Ph), 72.13 (CH-3), 69.56

(CH-1), 65.45 (CH₂-6), 20.92, 20.84, 20.73 (3£OAc); MS

(CI, NH₃): m/z (%): 532 (100) [MþNH₄^þ]; elemental

analysis: calcd (%) for C₂₇H₃₀O₈S (514.60): C 63.02, H

5.88; found C 63.05, H 6.06.

´

formed by Service de Microanalyse de l’Universite Pierre et

Marie Curie, 4 Place Jussieu, 75005 Paris, France. ¹H NMR

and ¹³C NMR spectra were recorded with a Bruker AC 250

or a Bruker DRX 400. Reactions were monitored by thin-

layer chromatography (TLC) on a precoated plate of silica

gel 60 F₂₅₄(layer thickness 0.2 mm; E. Merck, Darmstadt,

Germany) and detection by charring with sulfuric acid.

Flash column chromatography was performed on silica gel

60 (230–400 mesh, E. Merck).

5.2.1. 1,2,4,6-Tetra-O-acetyl-3-O-benzyl-5-C-vinyl-b-D-

glucopyranoside 7. Vinyl derivative

6

0.032 mol) was dissolved in a 1:1 mixture of 1,4-dioxane/

(14.66 g,

´

Y. Bleriot et al. / Tetrahedron 60 (2004) 6813–6828

6821

5.2.3. Phenyl 3-O-benzyl-4,6-O-benzylidene-5-C-vinyl-1-

thio-b-^D-glucopyranoside 9. Compound (10.83 g,

(CHPh), 83.65 (CH-1), 82.92 (CH-4), 77.72 (CH-3), 74.74

(CH₂Ph), 73.13 (CH-2), 72.90 (C-5), 70.62 (CH₂-6), 57.1

(CH₂-7); (CI, NH₃): m/z (%): 498 (100) [MþNH₄^þ];

elemental analysis: calcd (%) for C₂₇H₂₈O₆S (480.58): C

67.48, H 5.87; found C 67.13, H 6.08.

8

0.021 mol) was dissolved in CH₃OH (200 mL) and sodium

(500 mg) was added. The solution was stirred for 1 h at rt,

ion exchange resin IR-120 (20 g) was added and the reaction

mixture stirred for 1 h. The resin was ﬁltered and washed

with CH₃OH (100 mL). The solvent was evaporated and

the resulting oil was dried on a vacuum pump. The crude

diol was dissolved in dry DMF (100 mL) under argon.

Benzaldehyde dimethyl acetal (11.5 mL, 0.084 mol) and

camphorsulphonic acid (100 mg) were added under argon

and the soluton stirred at rt for 14 h. The reaction was

quenched by addition of triethylamine (2 mL). The solvent

was removed under vacuum and co-evaporated with

toluene (2£50 mL). Puriﬁcation by column chromatography

(EtOAc/cyclohexane 1:6) afforded the alcohol 9 (8.28 g,

0.016 mol, 74% yield) as an oil.

5.2.5. Phenyl 3-O-benzyl-4,6-O-benzylidene-2-O,5-C-

methylene-1-thio-b-^D-glucopyranoside 11. Diol 10

(0.76 g, 1.58 mmol) was dissolved in anhydrous pyridine

(10 mL) under argon. The solution was cooled to 0 8C.

Tosyl chloride (0.6 g, 3.16 mmol) and DMAP (20 mg) were

added under argon and the solution stirred at rt for 15 h.

Tosyl chloride (300 mg) was further added to complete the

reaction. After 7 h, the solvent was removed under reduced

pressure and co-evaporated with toluene (2£10 mL). The

crude tosylate was dried under vacuum for 1 h and was then

dissolved in anhydrous DMF (15 mL) under argon. Sodium

hydride (380 mg, 15.8 mmol) was added slowly and the

suspension was stirred at rt for 18 h. The reaction was

quenched with methanol (30 mL) and the solvent was

removed under vacuum and co-evaporated with toluene

(2£20 mL). The residue was dissolved in ethyl acetate

(80 mL) and washed with water (80 mL). Organic extracts

were dried over MgSO₄and the solution concentrated.

Puriﬁcation by column chromatography (EtOAc/cyclo-

hexane 1:4) afforded the bicycle 11 (0.65 g, 1.40 mmol,

88% yield) as an oil.

[a]²_D⁰¼28 (c¼1 in CHCl₃); H NMR (CDCl₃, 400 MHz):

1

d¼7.19–7.48 (m, 15H, 3£Ph), 6.28 (dd, J¼11.4, 17.9 Hz,

1H, H-7), 5.69 (s, 1H, CHPh), 5.51 (d, J¼11.3 Hz, 1H, H-8),

5.39 (d, J¼17.9 Hz, 1H, H-8⁰), 5.03 (d, J¼9.8 Hz, 1H, H-1),

4.98 (d, J¼11.5 Hz, 1H, CH₂Ph), 4.82 (d, J¼11.5 Hz, 1H,

CH₂Ph), 4.13 (d, J¼9.7 Hz, 1H, H-6), 3.96 (d, J¼9.7 Hz,

1H, H-6⁰), 3.81 (m, 2H, H-3, H-4), 3.60 (m, 1H, H-2), 2.77

(s, 1H, OH); ¹³C NMR (CDCl₃, 100 MHz): d¼138.03,

137.08, 130.93 (3£Cipso), 134.85 (CH-7), 128.98, 128.85,

128.43, 128.33, 128.17, 127.98, 127.75, 126.02 (Ph), 119.16

(CH₂-8), 102.30 (CHPh), 83.64 (CH-1), 83.00 (CH-4),

78.27 (CH-3), 77.25 (CH₂-6), 74.62 (CH₂Ph), 73.23 (CH-2),

72.51 (C-5); MS (CI, NH₃): m/z (%): 494 (100) [MþNH₄^þ];

elemental analysis: calcd (%) for C₂₈H₂₈O₅S (476.17): C

70.57, H 5.92; found C 70.56, H 5.97.

5.2.6. Spectroscopic data for phenyl 3-O-benzyl-4,6-O-

benzylidene-5-C-(2-tosyloxymethyl)-1-thio-b-^D-gluco-

pyranoside. [a]_D²⁰¼27 (c¼1 in CHCl₃); ¹H NMR (CDCl₃,

400 MHz): d¼7.81–7.30 (m, 19H, 4£Ph), 5.60 (s, 1H,

CHPh), 4.89 (d, J¼10.0 Hz, 1H, H-1), 4.84 (d, J¼11.4 Hz,

1H, CH₂Ph), 4.74 (d, J¼11.4 Hz, 1H, CH₂Ph), 4.62 (d,

J¼11.2 Hz, 1H, H-7), 4.54 (d, J¼11.2 Hz, 1H, H-7⁰), 4.34

(d, J¼10.8 Hz, 1H, H-6), 3.80 (d, J¼10.5 Hz, 1H, H-4),

3.72 (m, 1H, H-3), 3.65 (d, J¼10.8 Hz, 1H, H-6⁰), 3.55 (dd,

5.2.4. Phenyl 3-O-benzyl-4,6-O-benzylidene-5-C-hydroxy-

methyl-1-thio-b-^D-glucopyranoside 10. Compound

9

(1.1 g, 2.12 mmol) was dissolved in CH₂Cl₂(50 mL). The

solution was cooled to 278 8C. Ozone was bubbled through

the solution until appearance of a pale blue colour (2 min).

The reaction was then quenched by addition of dimethyl-

sulﬁde (0.2 mL). The solution was allowed to warm to rt for

1 h, the solvent was evaporated to afford the crude aldehyde

which was used directly for the next step. The crude

aldehyde was dissolved in EtOH (50 mL) at 0 8C, sodium

borohydride (92 mg, 2.54 mmol) was added slowly to the

solution and the reaction mixture was stirred at rt for 18 h.

The reaction was quenched with methanol (20 mL) and

the solvent was removed under reduced pressure and

co-evaporated with methanol (2£20 mL). The residue was

preadsorbed on silica. Puriﬁcation by column chroma-

tography (EtOAc/cyclohexane 1:3) afforded the diol 10

(858 mg, 1.79 mmol, 84% yield) as an oil.

1H, H-2), 2.48 (s, 3H, PhCH₃tosyl), 2.09 (s, 1H, OH); ¹³

C

NMR (CDCl₃, 100 MHz): d¼[145.13, 137.87, 136.55,

131.97, 131.53 (5£Cipso)], [132.15, 130.00, 129.97,

129.19, 129.12, 128.98, 128.62, 128.43, 128.18, 128.13,

128.07, 128.00, 127.96, 127.94, 127.89, 125.95 (4£Ph)],

102.69 (CHPh), 83.90 (CH-1), 82.46 (CH-4), 77.64 (CH-3),

74.86 (CH₂Ph), 73.17 (CH-2), 71.47 (C-5), 70.48 (CH₂-6),

63.35 (CH₂-7); (CI, NH₃): m/z (%): 652 (100) [MþNH₄^þ].

5.2.7. Data for bicycle 11. [a]²_D⁰¼2218 (c¼1 in CHCl₃);

¹H NMR (CDCl₃, 400 MHz): d¼7.58–7.30 (m, 15H,

3£Ph), 5.81 (dd, J¼2.3, 1.5 Hz, 1H, H-1), 5.64 (s, 1H,

CHPh), 4.32 (t, J¼2.7 Hz, 1H, H-2), 4.08 (ddd, J¼1.5, 2.7,

4.3 Hz, 1H, H-3), 4.₀04 (d, J¼11.3 Hz, 1H, H-6), 5.98 (d,

J¼11.3 Hz, 1H, H-6 ), 3.91 (dd, J¼1.9, 9.4 Hz, 1H, H-7),

4.85 (d, J¼11.8 Hz, 1H, CH₂Ph), 4.78 (d, J¼11.8 Hz, 1H,

CH₂Ph), 4.51 (dd, J¼1.7, 4.1 Hz, 1H, H-4), 4.51 (d,

J¼9.4 Hz, 1H, H-7⁰); ¹³C NMR (CDCl₃, 100 MHz): d¼

137.44, 136.95, 136.59 (3£Cipso), 130.61, 129.25, 129.03,

128.97, 128.36, 127.81, 127.76, 127.16, 126.15, 126.12

(3£Ph), 101.35 (CHPh), 86.54 (CH-1), 81.23 (CH-4),

78.31 (CH-3), 71.54 (CH₂Ph), 69.97 (CH₂-6), 67.99

(CH-2), 66.45 (CH₂-7), 66.01 (C-5); (CI, NH₃): m/z (%):

480 (100) [MþNH₄^þ]; elemental analysis: calcd (%) for

C₂₇H₂₆O₅S (462.57): C 70.10, H 5.67; found C 70.07, H

5.79.

[a]²_D⁰¼234 (c¼0.7 in CHCl₃); ¹H NMR (CDCl₃,

250 MHz): d¼7.53–7.07 (m, 15H, 3£Ph), 5.54 (s, 1H,

CHPh), 4.85 (d, J¼9.9 Hz, 1H, H-1), 4.77 (d, J¼11.5 Hz,

1H, CH₂Ph), 4.63 (d, J¼11.5 Hz, 1H, CH₂Ph), 4.33 (d,

J¼10.2 Hz, 1H, H-6), 4.04 (m, 1H, H-7), 3.94 (m, 1H, H-7⁰),

3.78–3.66 (m, 2H, H-3, H-4), 3.48 (d, J¼10.2 Hz, 1H,

H-6⁰), 3.43 (ddd, 1H, H-2), 2.73 (s, 1H, OH), 1.77 (s, 1H,

OH); ¹³C NMR (CDCl₃, 100 MHz): d¼139.08, 138.03,

132.02 (3£Cipso), 130.65, 129.97, 128.95, 128.54, 128.28,

128.22, 128.12, 128.07, 127.90, 125.94 (3£Ph), 102.69

´

Y. Bleriot et al. / Tetrahedron 60 (2004) 6813–6828

6822

5.2.8. para-Nitrophenyl 3-O-benzyl-4,6-O-benzylidene-2-

O,5-C-methylene-b-^D-glucopyranoside 12, para-nitro-

phenyl 3-O-benzyl-4,6-O-benzylidene-2-O,5-C-methyl-

ene-a-^D-glucopyranoside 13. Bicycle 11 (652 mg,

(144 mg, 0.953 mmol) in water (1.5 mL) was then added at

rt followed by dropwise addition over 10 min under

vigorous stirring of an aqueous solution (3 mL) of

Na₂S₂O₄(150 mg). After 24 h, the reaction mixture was

diluted with EtOAc (20 mL). The organic phase was washed

with a saturated aqueous solution of Na₂S₂O₃(10 mL).

Organic extracts were dried over MgSO₄and concentrated.

The residue was preadsorbed on silica gel. Puriﬁcation by

column chromatography (EtOAc/cyclohexane 1:2!1:1!

EtOAc) afforded the diol 14 (28 mg, 0.067 mmol, 42%

yield) as an oil.

˚

1.41 mmol), para-nitrophenol (235 mg, 1.69 mmol), 4 A

molecular sieves (1.3 g) were suspended in dry CH₂Cl₂

(20 mL) under argon and the suspension was stirred for

30 min and then cooled to 240 8C. N-Iodosuccinimide

(381 mg, 1.69 mmol) and triﬂic acid (19 mL, 0.211 mmol)

were added and the solution was stirred at 240 8C to afford

a red coloured solution. After 1 h, the reaction mixture was

quenched with aq. sat. NaHCO₃(30 mL) and diluted with

Et₂O (50 mL). The organic layer was separated, washed

with sat. Na₂S₂O₃(50 mL). The aqueous layer was

extracted with Et₂O (80 mL). Organic extracts were

combined, dried over MgSO₄and the solution concentrated.

Puriﬁcation by column chromatography (EtOAc/cyclo-

hexane 1:10) afforded the a-para-nitrophenyl derivative

13 (500 mg, 1.18 mmol, 72% yield) as an oil.

[a]²_D²¼2120 (c¼0.4 in CH₃OH); ¹H NMR (CD₃OD,

400 MHz): d¼8.42 (d, J¼9.3 Hz, 2H, PhNO₂), 8.26 (m,

2H, Ph), 7.83 (m, 1H, Ph), 7.68 (m, 2H, Ph), 7.53 (d,

J¼9.3 Hz, 2H, PhNO₂), 6.23 (dd, J¼1.1, 2.7 Hz, 1H, H-1),

5.63 (dd, J¼1.8, 4.8 Hz, 1H, H-4), 4.48 (m, 1H, H-3), 4.28

(m, 2H, H-2, H-7), 4.11 (dd, J¼1.8, 9.7 Hz, 1H, H-7⁰), 3.85

(d, J¼12.3 Hz, 1H, H-6), 3.74 (d, J¼12.3 Hz, 1H, H-6⁰); ¹³

C

NMR (CD₃OD, 100 MHz): d¼167.30, 144.20, 131.10,

(3£Cipso), 163.32 (CvO), 134.98, 131.06, 130.04 (Ph),

126.89, 118.22 (2£PhNO₂), 98.80 (CH-1), 77.40 (CH-4),

77.14 (C-5), 74.92 (CH-3), 69.96 (CH-2), 64.65 (CH₂-7),

62.31 (CH₂-6); MS (CI, NH₃): m/z (%): 435 (100)

[MþNH₄^þ]; HRMS (positive-ion CI, NH₃): calcd for

C₂₀H₂₃O₉N₂(MþNH₄^þ) 435.1404, found 435.1394.

[a]²_D²¼þ44 (c¼0.34 in CHCl₃); ¹H NMR (CDCl₃,

400 MHz): d¼8.25 (d, J¼9.2 Hz, 2H, PhNO₂), 7.40–7.55

(m, 10H, 2£Ph), 7.18 (d, J¼9.2 Hz, 2H, PhNO₂), 5.95

(d, J¼1.1 Hz, 1H, H-1), 5.65 (s, 1H, CHPh), 4.81 (d, J¼

11.6 Hz, 1H, CH₂Ph), 4.69 (d, J¼11.6 Hz, 1H, CH₂Ph),

4.57 (d, J¼9.7 Hz, 1H, H-7), 4.22 (dd, J¼1.1, 3.6 Hz, 1H,

H-2), 4.12 (m, 3H, H-3, H-4, H-7⁰), 4.03 (d, J¼11.2 Hz, 1H,

H-6), 3.91 (d, J¼11.2 Hz, 1H, H-6⁰); ¹³C NMR (CDCl₃,

100 MHz): d¼161.59, 142.43, 136.97, 136.61, (4£Cipso),

129.38, 128.52, 128.35, 128.14, 127.86, 126.12, 125.74,

116.29 (3£Ph), 101.90 (CHPh), 95.97 (CH-1), 81.92, 77.00

(CH-3, CH-4), 71.86 (CH₂Ph), 69.48 (CH₂-6), 68.19

(CH-2), 67.35 (C-5), 66.16 (CH₂-7); MS (CI, NH₃): m/z

(%): 509 (100) [MþNH₄^þ]; elemental analysis: calcd (%)

for C₂₇H₂₅O₈N (491.50): C 65.98, H 5.13, N 2.85; found C

65.81, H 5.32, N 2.75.

Further elution afforded the diol 15 (17 mg, 0.040 mmol,

26% yield) as an oil.

[a]²_D²¼2122 (c¼0.6 in CH₃OH); ¹H NMR (CD₃OD,

400 MHz): d¼8.29 (d, J¼9.3 Hz, 2H, PhNO₂), 8.10 (m,

2H, Ph), 7.72 (m, 1H, Ph), 7.72 (m, 2H, Ph), 7.56 (m, 2H,

Ph), 7.38 (d, J¼9.3 Hz, 2H, PhNO₂), 6.16 (d, J¼1.3, 2.8 Hz,

1H, H-1), 4.72 (d, J¼11.9 Hz, 1H, H-6), 4.57 (d, J¼

11.9 Hz, 1H, H-6⁰), 4.32 (dd, J¼1.8, 5.3 Hz, 1H, H-4), 4.23

(m, 1H, H-3), 4.21 (d, J¼9.3 Hz, 1H, H-7), 4.18 (t, J¼

2.8 Hz, 1H, H-2), 3.93 (dd, J¼1.8, 9.3 Hz, 1H, H-7⁰); ¹³C

NMR (CD₃OD, 100 MHz): d¼167.81, 144.01, 131.35,

(3£Cipso), 162.89 (CvO), 134.60, 130.84, 129.77 (Ph),

126.77, 118.23 (2£PhNO₂), 98.41 (CH-1), 77.10 (C-5),

76.88 (CH-3), 75.13 (CH-4), 69.98 (CH-2), 63.82 (CH₂-6),

63.72 (CH₂-7); MS (CI, NH₃): m/z (%): 435 (100)

[MþNH₄^þ]; HRMS (positive-ion CI, NH₃): calcd for

C₂₀H₂₃O₉N₂(MþNH₄^þ) 435.1404, found 435.1397.

Further elution afforded the b-para-nitrophenyl derivative

12 (130 mg, 0.26 mmol, 19% yield) as an oil.

[a]²_D²¼2265 (c¼0.21 in CHCl₃); ¹H NMR (CDCl₃,

400 MHz): d¼8.26 (d, J¼9.3 Hz, 2H, PhNO₂), 7.38–7.51

(m, 10H, 2£Ph), 7.13 (d, J¼9.3 Hz, 2H, PhNO₂), 5.96 (dd,

J¼1.3, 2.9 Hz, 1H, H-1), 5.59 (s, 1H, CHPh), 4.82 (d,

J¼11.7 Hz, 1H, CH₂Ph), 4.76 (d, J¼11.7 Hz, 1H, CH₂Ph),

4.50 (d, J¼9.4 Hz, 1H, H-7), 4.41 (dd, J¼1.8, 5.0 Hz, H-4),

4.23 (t, J¼2.7 Hz, 1H, H-2), 4.13 (ddd, J¼1.3, 2.7 Hz,

J¼5.0 Hz, 1H, H-3),₀4.10 (d, J¼11.5 Hz, 1H, H-6), 3.93 (d,

J¼11.5 Hz, 1H, H-6 ), 3.81 (dd, J¼1.9, 9.4 Hz, H-7⁰); ¹³C

NMR (CDCl₃, 100 MHz): d¼161.15, 142.51, 137.78,

136.73 (4£Cipso), 129.32, 128.41, 128.34, 127.83, 127.59,

126.07, 125.81, 116.23 (3£Ph), 101.26 (CHPh), 96.82

(CH-1), 81.12 (CH-4), 78.20 (CH-3), 71.74 (CH₂Ph), 69.66

(CH₂-6), 66.09 (C-5), 75.72 (CH₂-7), 75.56 (CH-2); MS

(CI, NH₃): m/z (%): 509 (100) [MþNH₄^þ]; elemental

analysis: calcd (%) for C₂₇H₂₅O₈N (491.50): C 65.98, H

5.13, N 2.85; found C 65.80, H 5.25, N 2.72.

5.2.10. para-Nitrophenyl 2-O,5-C-methylene-b-^D-gluco-

pyranoside 1. Compound 1 from diol 14. Diol 14 (20 mg,

0.048 mmol) was dissolved in CH₃OH (10 mL) and

CH₃ONa (200 mL of a 1 M methanolic solution) was

added. After 30 min, the reaction was complete and was

quenched by stirring with resin IR-120 (1 g) for 1 h. The

resin was ﬁltered and washed with CH₃OH (20 mL). The

solvent was removed under reduced pressure and puriﬁ-

cation by column chromatography (EtOAc) afforded the

triol 1 (11 mg, 0.035 mmol, 73% yield) as a foam.

Compound 1 from diol 15. The same procedure as the one

used above afforded triol 1 (12 mg, 0.038 mmol, 70%

yield).

5.2.9. para-Nitrophenyl 4-O-benzoyl-2-O,5-C-methylene-

b-^D-glucopyranoside 14 and para-nitrophenyl 6-O-ben-

zoyl-2-O,5-C-methylene-b-^D-glucopyranoside 15. The

b-para-nitrophenyl derivative 12 (78 mg, 0.158 mmol)

was dissolved in EtOAc (2 mL). A solution of NaBrO₃

[a]²_D²¼2128 (c¼0.55 in CH₃OH); ¹H NMR (400 MHz,

D₂O): d¼8.21 (d, J¼9.0 Hz, 2H, PhNO₂), 7.21 (d,

´

Y. Bleriot et al. / Tetrahedron 60 (2004) 6813–6828

6823

J¼9.0 Hz, 2H, PhNO₂), 6.01 (dd, J¼1.0, 2.6 Hz, 1H, H-1),

4.12 (t, J¼2.7 Hz, 1H, H-2), 4.06 (m, 1H, H-3), 4.02 (dd,

J¼1.6, 5.1 Hz, 1H, H-4), 3.91 (d, J¼9.8 Hz, 1H, H-7), 3.76

(dd, J¼1.6, 9.8 Hz, 1H, H-7⁰)₀, 3.68 (d, J¼12.8 Hz, 1H, H-6),

3.64 (d, J¼12.8 Hz, 1H, H-6 ); ¹³C NMR (100 MHz, D₂O):

d¼161.51, 142.67 (2£Cipso), 126.37 (Ph), 116.97 (Ph),

97.09 (CH-1), 76.76 (C-5), 74.62, 73.59, 67.99 (CH-2,

CH-3, CH-4), 62.46, 60.48 (CH₂-6, CH₂-7); MS (CI, NH₃):

m/z (%): 331 (100) [MþNH₄^þ]; HRMS (positive-ion CI,

NH₃): calcd for C₁₃H₁₉O₈N₂(MþNH^þ₄) 331.1141, found

331.1140.

4.16 (dd, J¼1.4, 4.5 Hz, 1H, H-2), 4.16 (d, J¼9.4 Hz, 1H,

H-7), 4.12 (dd, J¼1.0, 9.4 Hz, 1H, H-7⁰), 3.97 (m, 1H, H-4),

3.79 (d, J¼12.3 Hz, 1H, H-6), 3.75 (d, J¼12.3 Hz, 1H,

H-6⁰); ¹³C NMR (100 MHz, CD₃OD): d¼[164.01, 143.91,

(2£Cipso)], 126.97 (Ph), 118.02 (Ph), 97.16 (CH-1), 79.34

(C-5), 75.36, 74.38, 71.92 (CH-2, CH-3, CH-4), 65.07,

63.18 (CH₂-6, CH₂-7); MS (CI, NH₃): m/z (%): 331 (52)

[MþNH₄^þ]; elemental analysis: calcd (%) for C₁₃H₁₅O₈N

(313.26): C 49.84, H 4.83, N 4.47; found C 49.87, H 4.87, N

4.30.

5.2.13. Isopropyl 3-O-benzyl-4,6-O-benzylidene-2-O,5-C-

methylene-a-^D-glucopyranoside 18. Thiophenyl deriva-

tive 11 (500 mg, 1.08 mmol) was dissolved in dry iso-

propanol (50 mL) and NBS (98 mg, 5.5 mmol) was added

under argon. The slurry solution was stirred for 48 h at rt,

ﬁltered and concentrated. The crude product was puriﬁed

by column chromatography (EtOAc/cyclohexane 1:10) to

afford compound 18 (290 mg, 0.070 mmol, 64% yield) as a

colourless oil.

5.2.11. para-Nitrophenyl 4-O-benzoyl-2-O,5-C-methyl-

ene-a-^D-glucopyranoside 16 and para-nitrophenyl 6-O-

benzoyl-2-O,5-C-methylene-a-^D-glucopyranoside

17.

The same procedure as the one used to obtain compounds

14 and 15 was applied to the a-para-nitrophenyl derivative

13 (304 mg, 0.619 mmol) to afford the diol 16 (137 mg,

0.328 mmol, 53% yield) as an oil.

[a]²_D²¼þ100 (c¼0.25 in CH₃OH); ¹H NMR (CD₃OD,

400 MHz): d¼8.44 (d, J¼9.3 Hz, 2H, PhNO₂), 8.25 (m,

2H, Ph), 7.83 (m, 1H, Ph), 7.72 (m, 2H, Ph), 7.48 (d, J¼

9.3 Hz, 2H, PhNO₂), 6.20 (d, J¼1.4 Hz, 1H, H-1), 5.31 (m,

2H, H-1, H-4), 4.34–4.30 (m, 4H, H-2, H-3, H-7, H-7⁰), 3.81

(d, J¼12.5 Hz, 1H, H-6), 3.73 (d, J¼12.5 Hz, 1H, H-6⁰);

¹³C NMR (CD₃OD, 100 MHz): d¼167.32, 144.08, 131.20

(3£Cipso), 163.79 (CvO), 135.00, 131.01, 130.08 (Ph),

127.02, 118.10 (2£PhNO₂), 97.16 (CH-1), 78.21 (C-5),

76.17 (CH-4), 73.21, 71.45 (CH-2, CH-3), 65.84 (CH₂-7),

62.80 (CH₂-6); MS (CI, NH₃): m/z (%): 435 (100)

[MþNH₄^þ]; elemental analysis: calcd (%) for C₂₀H₁₉O₉N

(417.37): C 57.55, H 4.59, N 3.35; found C 57.64, H 4.77, N

3.22.

[a]²_D⁰¼238 (c¼0.6 in CHCl₃); ¹H NMR (CDCl₃,

400 MHz): d¼7.53–7.30 (m, 10H, 2£Ph), 5.58 (s, 1H,

CHPh), 5.30 (s, 1H, H-1), 4.77 (d, J¼11.7 Hz, 1H, CHPh),

4.64 (d, J¼11.7 Hz, 1H, CHPh), 4.45 (d, J¼9.3 Hz, 1H,

H-7), 4.05 (dd, J¼0.7, 9.3 Hz, 1H, H-7⁰), 4.01 (t, J¼6.2 Hz,

1H, H-8), 3.99 (m, 2H, H-3, H-4), 3.98 (d, J¼11.1 Hz, 1H,

H-6), 3.91 (m, 1H, H-2), 3.83 (d, J¼11.1 Hz, 1H, H-6⁰),

1.33 (d, J¼6.2 Hz, 3H, CH₃-iPr),1.22 (d, J¼6.2 Hz, 3H,

CH₃-iPr); ¹³C NMR (CDCl₃, 62.9 MHz): d¼138.3, 137.7

(2£Cipso), 129.2–126.2 (2£Ph), 101.8 (CHPh), 95.8

(CH-1), 82.3 (CH-3 or CH-4), 77.6 (CH-3 or CH-4), 71.6

(CH₂Ph), 70.5 (CH-8), 70.0 (CH₂-6), 69.0 (CH-2), 66.2

(CH₂-7), 64.9 (C-5), 23.8, 21.9 (2£CH₃-iPr); (CI, NH₃): m/z

(%): 413 (100) [MþH^þ]; HRMS (positive-ion CI, NH₃):

calcd for C₂₄H₂₉O₆(MþH^þ) 413.1964, found 413.1963.

Further elution afforded the diol 17 (102 mg, 0.244 mmol,

39% yield) as an oil.

5.2.14. Isopropyl 2-O,5-C-methylene-a-^D-glucopyrano-

side 3. A round-bottom ﬂask, ﬁtted with an ammonia

condenser, was charged with 18 (200 mg, 0.49 mmol), dry

THF (50 mL) and ammonia (,10 mL) and was cooled to

278 8C. A small amount of lithium was added and the

reaction was stirred for 2 min and quenched with NH₄Cl.

The reaction mixture was allowed to warm to rt and

concentrated. The crude product was puriﬁed by column

chromatography (EtOAc/cyclohexane 3:1) to afford com-

pound 3 (60 mg, 0.26 mmol, 52% yield) as a colourless oil.

[a]²_D²¼þ111 (c¼0.3 in CH₃OH); ¹H NMR (CD₃OD,

400 MHz): d¼8.27 (d, J¼9.3 Hz, 2H, PhNO₂), 7.97 (m,

2H, Ph), 7.68 (m, 1H, Ph), 7.50 (m, 2H, Ph), 7.31 (d,

J¼9.3 Hz, 2H, PhNO₂), 6.12 (d, J¼1.4 Hz, 1H, H-1), 4.74

(d, J¼12.1 Hz, 1H, H-6), 4.50 (d, J¼12.1 Hz,₀1H, H-6⁰),

4.29 (m, 2H, H-4, H-7), 4.24 (m, 2H, H-2, H-7 ), 4.02 (m,

1H, H-3); ¹³C NMR (CD₃OD, 100 MHz): d¼167.65,

143.79, 131.20, (3£Cipso), 163.28 (CvO), 134.54,

130.73, 129.70 (Ph), 126.87, 117.97 (2£PhNO₂), 96.43

(CH-1), 78.16 (C-5), 75.40, 75.31, 71.96 (CH-2, CH-3,

CH-4), 65.35 (CH₂-6), 64.79 (CH₂-7); MS (CI, NH₃): m/z

(%): 435 (100) [MþNH₄^þ]; elemental analysis: calcd (%)

for C₂₀H₁₉O₉N (417.37): C 57.55, H 4.59, N 3.35; found C

57.70, H 4.89, N 3.13.

[a]²_D²¼258 (c¼1.65 in CH₃OH); ¹H NMR (CD₃OD,

400 MHz): d¼5.47 (dd, J¼1.5, 2.7 Hz, 1H, H-1), 4.24 (m,

J¼6.2 Hz, 1H, H-8), 4.05 (dd, J¼1.8, 4.3 Hz, 1H, H-4), 3.99

(d, J¼9.2 Hz, 1H, H-7), 3.92 (m, 1H,₀H-3), 3.87 (t, J¼

2.7 Hz, 1H, H-2), 3.78 (s, 2H, H-6, H-6 ), 3.77 (dd, J¼1.8,

9.2 Hz, 1H, H-7⁰), 1.43 (d, J¼6.2 Hz, 3H, CH₃-iPr), 1.34 (d,

J¼6.2 Hz, 3H, CH₃-iPr); ¹³C NMR (D₂O, 100 MHz): d¼

99.20 (CH-1), 77.71 (CH-3), 76.79 (C-5), 76.77 (CH-4),

72.15 (CH-8), 69.64 (CH-2), 63.62 (CH₂-7), 62.96 (CH₂-6),

24.33 (CH₃-iPr), 22.24 (CH₃-iPr); MS (CI, NH₃): m/z (%):

252 (100) [MþNH₄^þ]; HRMS (positive-ion CI, NH₃): calcd

for C₁₀H₂₂O₆N (MþNH^þ₄) 252.1447, found 252.1450.

5.2.12. para-Nitrophenyl 2-O,5-C-methylene-a-^D-gluco-

pyranoside 2. The same procedure as the one used to obtain

compound 1 was applied to diol 17 (102 mg, 0.244 mmol) to

afford the triol 2 (70 mg, 0.223 mmol, 92% yield), which

was recrystallized from EtOAc.

[a]²_D²¼þ106 (c¼0.94 in CH₃OH); mp 229–230 8C

1

(EtOAc); H NMR (400 MHz, CD₃OD): d¼8.38 (d, J¼

9.2 Hz, 2H, PhNO₂), 7.44 (d, J¼9.2 Hz, 2H, PhNO₂), 6.07

(d, J¼1.4 Hz, 1H, H-1), 4.18 (dd, J¼1.6, 4.5 Hz, 1H, H-3),

5.2.15. Isopropyl 2,4,6-tri-O-acetyl-3-O-benzyl-5-C-

vinyl-b-^D-glucopyranoside 19. Tetraacetate

7 (20 g,

´

Y. Bleriot et al. / Tetrahedron 60 (2004) 6813–6828

6824

43.1 mmol) was dissolved in dry CH₂Cl₂(230 mL) and

˚

extra dry isopropanol (4.83 mL) and powdered 4 A

(d, J¼6.2 Hz, 3H, CH₃-iPr),1.25 (d, J¼6.2 Hz, 3H, CH₃-iPr);

¹³C NMR (CDCl₃, 100 MHz): d¼138.33, 137.24 (2£Cipso),

136.23 (CH-7), 128.98, 128.33, 128.20, 127.91, 127.67,

126.10 (Ph), 118.25 (CH₂-8), 102.38 (CHPh), 97.47 (CH-1),

83.24 (CH-4), 77.46 (CH₂-6), 77.28 (CH-3), 75.36 (CH-2),

74.41 (CH₂Ph), 71.97 (CH-9), 69.75 (C-5), 23.40, 22.00

(2£CH₃-iPr); MS (CI, NH₃): m/z (%): 444 (100) [MþNH₄^þ];

elemental analysis: calcd (%) for C₂₅H₃₀O₆(426.5): C 70.40,

H 7.09; found C 70.50, H 7.22.

molecular sieves (32 g) were added. The solution was

stirred for 2 h, cooled to 278 8C and TMSOTf (11.7 mL,

64.6 mmol) was added slowly. The reaction mixture was

allowed to warm up to room temperature under stirring and

was stirred for another 5 h. The reaction mixture was then

quenched with Et₃N, ﬁltered through celite and washed

with water. The organic layer was dried over MgSO₄and

concentrated. Puriﬁcation by column chromatography

(EtOAc/cyclohexane 1:3) afforded the isopropyl derivative

19 (15.3 g, 33 mmol, 76% yield) as a colourless syrup.

5.2.17. Isopropyl 3-O-benzyl-4,6-O-benzylidene-5-C-

hydroxymethyl-b-^D-glucopyranoside 21. Ozone was

passed through a stirred solution of oleﬁn 20 (1.0 g,

2.3 mmol) in anhydrous CH₂Cl₂(50 mL) cooled to

278 8C until the appearance of a pale blue colour. The

reaction mixture was quenched with (CH₃)₂S (0.2 mL) and

allowed to warm to room temperature. The solvent was

evaporated. The residue was dissolved in methanol (20 mL)

and the solution was cooled to 0 8C, NaBH₄(250 mg,

6.9 mmol) was added and the reaction mixture was warmed

to room temperature and stirred for 1 h, cooled to 0 8C and

quenched with NH₄Cl. The reaction mixture was evapo-

rated, the residue dissolved in ethyl acetate, washed with

water and brine, dried over Na₂SO₄and concentrated. The

crude product was puriﬁed by column chromatography

(EtOAc/cyclohexane 1:3) to afford the diol 21 (0.7 g, 70%)

as a solid.

[a]²_D⁰¼279 (c¼0.86 in CHCl₃); ¹H NMR (CDCl₃,

400 MHz): d¼7.26–7.35 (m, 5H, Ph), 6.02 (dd, J¼11.1,

17.8 Hz, 1H, H-7), 5.62 (dd, J¼1.2, 17.8 Hz, 1H, H-8), 5.59

(dd, J¼0.9, 11.1 Hz, 1H, H-8⁰), 5.44 (d, J¼10.1 Hz, 1H, H-

4), 5.08 (dd, J¼8.0, 9.5 Hz, 1H, H-2), 4.75 (d, J¼8.0 Hz,

1H, H-1), 5.07 (dd, J¼9.3, 10.1 Hz, 1H, H-3), 4.63 (d,

J¼11.7 Hz, 1H, CHPh), 4.59 (d, J¼11.7 Hz, 1H, CHPh),

4.08 (d, J¼12.2 Hz, 1H, H-6), 3.88 (m, J¼6.2 Hz, 1H, H-9),

3.83 (d, J¼12.2 Hz, 1H, H-6⁰), 2.12, 2.01 (2£s, 9H,

3£OAc), 1.43 (d, J¼6.2 Hz, 3H, CH₃-iPr), 1.34 (d,

J¼6.2 Hz, 3H, CH₃-iPr); ¹³C NMR (CDCl₃, 100 MHz):

d¼170.88, 169.03, 168.99 (3£CvO), 137.87 (Cipso),

132.19 (CH-7), 128.36, 127.71, 127.62 (Ph), 120.49 (CH₂-

8), 95.49 (CH-1), 77.84 (CH-3), 76.63 (C-5), 73.89

(CH₂Ph), 73.70 (CH-2), 72.25 (CH-9), 69.77 (CH-4),

65.68 (CH₂-6), 23.34 (CH₃-iPr), 22.06 (CH₃-iPr), 20.88,

20.78 (3£OAc); MS (CI, NH₃): m/z (%): 582 (100)

[MþNH₄^þ]; elemental analysis: calcd (%) for C₂₄H₃₂O₉

(564.20): C 62.06, H 6.94; found C 62.08, H 6.93.

[a]²_D⁰¼246 (c¼0.86 in CHCl₃); mp 141 8C (n-pentane/ethyl

1

acetate); H NMR (CDCl₃, 400 MHz): d¼7.52–7.30 (m,

10H, 2£Ph), 5.68 (s, 1H, CHPh), 4.92 (d, J¼11.7 Hz, 1H,

CH₂Ph), 4.88 (d, J¼7.7 Hz, 1H, H-1), 4.81 (d, J¼11.7 Hz,

1H, CH₂Ph), 4.36 (d, J¼10.4 Hz, 1H, H-6), 4.22 (dd, J¼7.1,

12.0 Hz, 1H, H-7), 4.09 (dd, J¼2.7, 12.0 Hz, 1H, H-7⁰), 4.03

(m, J¼6.2 Hz, 1H, H-8), 3.97 (d, J¼10.2 Hz, 1H, H-4), 3.88

(dd, J¼8.2, 10.2 Hz, 1H, H-3), 3.66 (dd, J¼1.2, 10.4 Hz,

1H, H-6⁰), 3.62 (dd, J¼2.7, 7.9 Hz, 1H, H-2), 2.62 (d, J¼

7.9 Hz, 1H, OH-2), 1.82 (dd, J¼3.8, 7.1 Hz, 1H, OH-7),

1.32 (d, J¼6.2 Hz, 3H, CH₃-iPr),1.27 (d, J¼6.2 Hz, 3H,

CH₃-iPr); ¹³C NMR (CDCl₃, 100 MHz): d¼138.31, 137.13

(2£Cipso), 129.07–126.00 (2£Ph), 102.59 (CHPh), 97.79

(CH-1), 83.08 (CH-4), 77.02 (CH-3), 75.40 (CH-2), 74.35

(CH₂Ph), 72.43 (CH-8), 70.90 (CH₂-6), 70.35 (C-5), 58.30

(CH₂-7), 23.39, 21.97 (2£CH₃-iPr); (CI, NH₃): m/z (%): 448

(35) [MþNH₄^þ]; elemental analysis: calcd (%) for

C₂₄H₃₀O₇(430,49): C 66.96, H 7.02; found C 66.69, H 7.21.

5.2.16. Isopropyl 3-O-benzyl-4,6-O-benzylidene-5-C-

vinyl-b-^D-glucopyranoside 20. Compound 19 (2.3 g,

4.96 mmol) was dissolved in dry CH₃OH (70 mL) under

argon and sodium (50 mg) was added. The solution was

stirred for 16 h, ion exchange resin IR-120 (5 g) was added

and the reaction mixture stirred for 1 h. The resin was

ﬁltered and washed with CH₃OH (30 mL). The solvent was

evaporated and the resulting oil was dissolved in ethyl

acetate (50 mL) and washed with water (30 mL). The

organic layer was dried over MgSO₄and evaporated. To a

solution of crude triol in dry CH₂Cl₂(75 mL) was added

benzaldehyde dimethyl acetal (1.1 mL, 7.2 mmol) and

camphorsulphonic acid (50 mg) under argon and the

solution was stirred at rt for 12 h. The reaction mixture

was quenched with NaHCO₃. The organic layer was washed

with water and brine, dried over MgSO₄and concentrated.

Puriﬁcation by column chromatography (EtOAc/cyclo-

hexane 1:6) afforded alcohol 20 (1.7 g, 3.99 mmol, 81%)

as a white needles.

5.2.18. Isopropyl 3-O-benzyl-4,6-O-benzylidene-2-O,5-C-

methylene-b-^D-glucopyranoside 22. To a stirred solution

of diol 21 (700 mg, 1.6 mmol) in anhydrous pyridine

(10 mL) was added TsCl (370 mg, 1.95 mmol), followed

by DMAP (50 mg). The reaction mixture was stirred for

12 h at 60 8C, cooled to room temperature and quenched

with water. Ethyl acetate was added and the organic layer

was washed with water and brine, dried over Na₂SO₄and

concentrated. The crude product was puriﬁed by column

chromatography (EtOAc/cyclohexane 1:5) yielding the

corresponding tosylate as a colourless oil (700 mg,

1.2 mmol, 74% yield).

[a]²_D⁰¼235 (c¼0.62 in CHCl₃); mp 99 8C (n-pentane/

1

EtOAc); H NMR (CDCl₃, 400 MHz): d¼7.93–7.56 (m,

10H, 2£Ph), 6.37 (dd, J¼11.2, 18.0 Hz, 1H, H-7), 5.70 (s,

1H, CHPh), 5.65 (dd, J¼1.2, 18.0 Hz, 1H, H-8), 5.57 (dd,

J¼1.2, 11.2 Hz, 1H, H-8⁰), 4.97 (d, J¼11.7 Hz, 1H, CH₂Ph),

4.84 (d, J¼7.7 Hz, 1H, H-1), 4.83 (d, J¼11.7 Hz, 1H,

CH₂Ph), 4.07 (d, J¼9.7 Hz, 1H, H-6), 4.03 (m, J¼6.2 Hz

1H, H-9), 3.95 (d, J¼9.7 Hz, 1H, H-6⁰), 3.88 (d, J¼10.1 Hz,

1H, H-4), 3.75 (dd, J¼8.8, 10.1 Hz, 1H, H-3), 3.61 (dt,

J¼2.4, 7.9 Hz, 1H, H-2), 2.48 (d, J¼2.1 Hz, 1H, OH),1.34

5.2.19. Spectroscopic data for tosylate. ¹H NMR (CDCl₃,

400 MHz): d¼7.86 (d, 2H, aromatic H), 7.84–7.30 (m, 12H,

aromatic H), 5.59 (s, 1H, CHPh), 4.87 (d, J¼11.7 Hz, 1H,

´

Y. Bleriot et al. / Tetrahedron 60 (2004) 6813–6828

6825

CHPh), 4.86 (d, J¼7.9 Hz, 1H, H-1), 4.78 (d, J¼11.7 Hz,

1H, CHPh), 4.54 (s, 2H, H-7, H-7⁰), 4.26 (d, J¼10.7 Hz, 1H,

H-6), 4.06 (m, J¼6.2 Hz, 1H, H-8), 3.89 (d, J¼10.3 Hz, 1H,

H-4), 3.72 (dd, J¼8.7, 10.3 Hz, 1H, H-3), 3.65 (d, J¼

10.7 Hz, 1H, H-6⁰), 3.60 (dt, J¼2.2, 8.2 Hz, 1H, H-2), 2.47

(s, 3H, CH₃-Ts), 2.44 (d, J¼2.5 Hz, 1H, OH-2), 1.31 (d,

J¼6.2 Hz, 3H, CH₃-iPr), 1.26 (d, J¼6.2 Hz, 3H, CH₃-iPr);

¹³C NMR (CDCl₃, 100 MHz): d¼145.13, 136.70 (2£

Cipso tosyl), 138.18, 132.29 (2£Cipso), 129.98–125.94

(2£Ph), 102.67 (CHPh), 97.62 (CH-1), 82.83 (CH-4), 77.01

(CH-3), 75.33 (CH-2), 74.60 (CH₂Ph), 72.82 (CH-8),

70.68 (CH₂-6), 68.89 (C-5), 64.29 (CH₂-7), 23.31, 21.99

(2£CH₃-iPr), 21.67 (CH₃tosyl); (CI, NH₃): m/z

(%): 602 (100) [MþNH₄^þ]; HRMS (positive-ion CI,

NH₃): calcd for C₃₁H₄₀O₉NS (MþNH^þ₄) 602.2424, found

602.2430.

1.35 (d, J¼6.2 Hz, 3H, CH₃-iPr); ¹³C NMR (100 MHz,

CD₃OD): d¼95.86 (CH-1), 77.83 (C-5), 75.72 (CH-3),

74.88 (CH-4), 72.69 (CH-2), 71.12 (CH-8), 65.00 (CH₂-7),

63.77 (CH₂-6), 24.56 (CH₃-iPr), 22.41 (CH₃-iPr); MS (CI,

NH₃): m/z (%): 252 (100) [MþNH₄^þ]; HRMS_þ(positive-ion

CI, NH₃): calcd for C₁₀H₂₂O₆N (MþNH₄) 252.1447,

found 252.1448.

5.2.21. Isopropyl 3-O-benzyl-2-O-tert-butyldimethylsilyl-

4,6-O-isopropylidene-5-C-vinyl-b-^D-glucopyranoside 23.

Sodium (600 mg, 26.1 mmol) was added at 0 8C to a

solution of compound 19 (15.1 g, 32.3 mmol) in methanol

(300 mL). After 8 h of stirring at rt, the reaction mixture was

neutralized with ion exchange resin IR-120 H^þstirring for

1 h. The mixture was ﬁltered, eluted with methanol and the

solvent removed under vacuum to afford the corresponding

triol (10.43 g, 30.86 mmol, 95%), which was used directly

for the next reaction.

The tosylate (500 mg, 0.86 mmol) was dissolved in dry

DMF (5 mL) under argon. The solution was cooled to 0 8C

and sodium hydride (100 mg, 60% in oil, 2.5 mmol) was

added and the reaction mixture was stirred for 1 h at room

temperature and quenched with NH₄Cl. Ethyl acetate was

added and the organic layer was washed with water, brine,

dried over Na₂SO₄and concentrated. The crude product was

puriﬁed by column chromatography (EtOAc/cyclohexane

1:8) yielding compound 22 (340 mg, 95%) as a colourless

oil.

Triol (8.89 g, 26.3 mmol) was dissolved in dry acetone

(39 mL), and 2,2⁰-dimethoxypropane (39 mL) followed by

camphorsulphonic acid (610 mg, 2.63 mmol) were added.

The reaction was stirred at rt overnight under argon, then

quenched by addition of a saturated aqueous solution of

NaHCO₃and extracted with dichloromethane. The organic

layer was dried over MgSO₄, concentrated and the residue

was puriﬁed by column chromatography (cyclohexane/

EtOAc 6:1) to afford the corresponding 4,6-O-isopropyl-

idene derivative (8.6 g, 22.75 mmol, 86%) as a white

powder.

[a]²_D⁰¼242 (c¼0.8 in CHCl₃); ¹H NMR (CDCl₃,

400 MHz): d¼7.49–7.30 (m, 10H, aromatic H), 5.57 (s,

1H, CHPh), 5.34 (dd, J¼1.2, 2.5 Hz, 1H, H-1), 4.72 (s, 2H,

CH₂Ph), 4.40 (d, J¼9.2 Hz, 1H, H-7), 4.35 (dd, J¼1.8,

4.8 Hz, 1H, H-3 or H-4), 4.03 (d, J¼11.2 Hz, 1H, H-6), 4.01

(t, J¼6.1 Hz, 1H, H-3 or H-4), 3.99 (m, J¼6.2 Hz, 1H, H-8),

3.97 (t, J¼2.5 Hz, 1H, H-2), 3.89₀(d, J¼11.2 Hz, 1H, H-6⁰),

3.69 (dd, J¼1.9, 9.2 Hz, 1H, H-7 ), 1.34 (d, J¼6.2 Hz, 3H,

CH₃-iPr),1.24 (d, J¼6.2 Hz, 3H, CH₃-iPr); ¹³C NMR

(CDCl₃, 100 MHz): d¼138.31, 137.18 (2£Cipso),

129.14–126.12 (2£Ph), 101.14 (CHPh), 97.91 (CH-1),

81.46 (CH-3 or CH-4), 78.57 (CH-3 or CH-4), 71.22

(CH₂Ph), 70.43 (CH-8), 70.24 (CH₂-6), 66.56 (CH-2), 65.91

(CH₂-7), 64.89 (C-5), 23.65, 21.77 (2£CH₃-iPr); (CI, NH₃):

m/z (%): 430 (100) [MþNH₄^þ]; elemental analysis: calcd

(%) for C₂₄H₂₈O₆(412.48): C 69.88, H 6.84; found C 70.08,

H 7.10.

This alcohol (8.23 g, 21.77 mmol) was dissolved in dry

DMF (55 mL) and TBDMSCl (4.27 g, 28.3 mmol) followed

by imidazole (1.92 g, 28.3 mmol) were added under argon.

The reaction mixture was stirred at 60 8C for 3.5 h, then

cooled to rt, and ﬁnally poured in a water–ice mixture and

extracted with ether. The organic layer was dried over

MgSO₄, concentrated and the residue was puriﬁed by

column chromatography (cyclohexane/EtOAc 4:1) to afford

compound 23 (10.45 g, 21.2 mmol, 97%) as a crystalline

solid.

[a]²_D⁰¼244 (c¼0.92 in CHCl₃); mp 113 8C (n-pentane/

1

EtOAc); H NMR (CDCl₃, 400 MHz): d¼7.50–7.30 (m,

5H, Ph), 6.33 (dd, J¼11.3, 17.9 Hz, 1H, H-7), 5.60 (dd,

J¼1.5, 17.9 Hz, 1H, H-8⁰), 5.53 (dd, J¼1.3, 11.3 Hz, 1H,

H-8), 4.85 (d, J¼11.1 Hz, 1H, CHPh), 4.71 (d, J¼7.2 Hz,

1H, H-1), 4.69 (d, J¼11.1 Hz, 1H, CHPh), 4.02 (m, J¼

6.2 Hz, 1H, H-9), 3.93 (d, J¼10.1 Hz, 1H, H-6⁰), 3.85 (d,

J¼9.5 Hz, 1H, H-4), 3.64 (d, J¼10.1 Hz, 1H, H-6), 3.50 (m,

2H, H-2, H-3), 1.47 (s, 3H, CH₃), 1.46 (s, 3H, CH₃), 1.29 (d,

J¼6.2 Hz, 3H, CH₃-iPr), 1.20 (d, J¼6.2 Hz, 3H, CH₃-iPr),

5.2.20. Isopropyl 2-O,5-C-methylene-b-^D-glucopyrano-

side 4. Compound 22 (300 mg, 0.728 mmol) was dissolved

in dry methanol (10 mL) and 10% Pd/C (30 mg) was added.

The solution was purged with hydrogen and stirred at rt

overnight. After completion of the reaction, the reaction

mixture was ﬁltered through celite and washed with

methanol. The solvent was concentrated and the crude

product was puriﬁed by column chromatography (EtOAc/

0.93 (s, 9H, tBu), 0.12 (s, 3H, CH₃), 0.08 (s, 3H, CH₃); ¹³

C

NMR (CDCl₃, 100 MHz): d¼138.87 (Cipso), 136.58

(CH-7), 128.12, 128.06, 127.34 (Ph), 117.70 (CH₂-8),

99.96 (C(CH₃)₂), 97.45 (CH-1), 78.91 (CH-2), 73.33

(CH-4), 75.96 (CH-3), 74.61 (CH₂Ph), 71.51 (CH₂-6),

70.58 (CH-9), 72.43 (CH-8), 69.90 (C-5), 29.18, 18.92

(2£CH₃), 25.92 (tBu), 23.48, 21.56 (2£CH₃-iPr), 24.08,

24.31 (2£CH₃-Si); (CI, NH₃): m/z (%): 510 (10)

cyclohexane 2:1) to afford compound

0.598 mmol, 82% yield) as colourless oil.

4 (140 mg,

[a]²_D²¼þ20 (c¼0.44 in CH₃OH); ¹H NMR (400 MHz,

CD₃OD): d¼5.36 (d, J¼1.6 Hz, 1H, H-1), 4.27 (m, J¼

6.2 Hz, 1H, H-8), 4.13 (dd, J¼1.3, 9.0 Hz, 1H, H-7), 4.07

(dd,₀J¼1.6, 4.5 Hz, 1H, H-3), 4.03 (dd, J¼0.9, 9.0 Hz, 1H,

H-7 ), 3.85 (dd, J¼1.6, 4.5 Hz, 1H, H-2), 3.83 (m, 1H, H-4),

3.73 (s, 2H, H-6, H-6⁰), 1.47 (d, J¼6.2 Hz, 3H, CH₃-iPr),

þ

[MþNH₄], 493 (20) [MþH^þ], 392 (100); HRMS (posi-

tive-ion CI, NH₃): calcd for C₂₇H₄₅O₆Si (MþH^þ) 493.2985,

found 493.2982.

´

Y. Bleriot et al. / Tetrahedron 60 (2004) 6813–6828

6826

5.2.22. Isopropyl 3-O-benzyl-2-O-tert-butyldimethylsilyl-

4,6-O-isopropylidene-5-C-methanoate-b-^D-glucopyra-

noside 24. Ozone was passed through a stirred solution of

oleﬁn 23 (1.0 g, 2.03 mmol) in CH₂Cl₂(50 mL) cooled to

278 8C for 4 h. The reaction mixture was quenched with

(CH₃)₂S (0.2 mL) and allowed to warm to room tempera-

ture. The solvent was evaporated. The crude carboxylic acid

was dissolved in dry DMF (20 mL). Iodomethane (8 mL)

and KHCO₃(570 mg) were added and the reaction mixture

was stirred under argon for 16 h. The solvent was removed

under reduced pressure and the residue dissolved in EtOAc

and washed with water and brine. The organic layer was

dried over MgSO₄and concentrated. Puriﬁcation by column

chromatography (cyclohexane/EtOAc 10:1) afforded the

methyl ester derivative 24 (744 mg, 1.42 mmol, 70% yield)

as an oil.

(2£CH₃-isopropylidene), 23.42, 21.69 (2£CH₃-iPr); (CI,

NH₃): m/z (%): 396 (100) [MþNH₄^þ]; HRMS (positive-ion

CI, NH₃): calcd for C₂₀H₂₇O₇(MþH^þ) 379.1757, found

379.1759.

5.2.24. Isopropyl 2-O,5-C-carbonyl-b-^D-glucopyranoside

5. Compound 25 (53 mg, 0.14 mmol) was dissolved in

AcOH/H₂O (3:2, 2 mL) and stirred at 60 8C for 3.5 h. The

solvent was removed under reduced pressure and the residue

co-evaporated with toluene (2£5 mL) to afford the crude

diol, which was used directly in the next step. The diol

(47 mg, 0.139 mmol) was dissolved in EtOAc (10 mL) and

Pd/C (10 mg) was added. The suspension was stirred under

H₂for 1 h at rt, ﬁltered through celite (eluted with EtOAc)

and the solvent was removed under reduced pressure.

Puriﬁcation by column chromatography (cyclohexane/

EtOAc 1:1) afforded compound 5 (29 mg, 0.121 mmol,

87% yield) as crystalline compound.

[a]²_D⁰¼218 (c¼1.2 in CHCl₃); ¹H NMR (CDCl₃,

400 MHz): d¼7.38–7.30 (m, 5H, Ph), 4.93 (d, J¼10.8 Hz,

1H, CHPh), 4.72 (d, J¼10.8 Hz, 1H, CHPh), 4.36 (d, J¼

7.8 Hz, 1H, H-1), 4.18 (d, J¼9.9 Hz, 1H, H-6), 4.13 (dd,

J¼9.8, 8.1 Hz, 1H, H-3), 4.00 (m, J¼6.2 Hz, 1H, H-8), 3.89

(d, J¼10.1 Hz, 1H, H-4), 3.88 (s, 3H, CO₂CH₃), 3.86 (d,

J¼9.9 Hz, 1H, H-6⁰), 3.49 (t, J¼7.9 Hz, 1H, H-2), 1.48 (s,

1H, CH₃-isopropylidene), 1.44 (s, 1H, CH₃-isopropylidene),

1.25 (d, J¼6.2 Hz, 3H, CH₃-iPr), 1.18 (d, J¼6.2 Hz, 3H,

CH₃-iPr), 0.91 (s, 9H, tBu), 0.09 (s, 3H, SiCH₃), 0.07 (s, 3H,

SiCH₃); ¹³C NMR (CDCl₃, 100 MHz): d¼169.88 (CvO),

138.96 (Cipso), 129.68, 128.11, 128.06, 127.31 (Ph), 100.20

(C(CH₃)₂), 99.54 (CH-1), 78.98 (CH-3), 76.02 (CH-4),

75.18 (CH-2), 74.66 (CH₂Ph), 71.71 (C-5), 71.34 (CH-8),

67.02 (CH₂-6), 52.17 (CO₂CH₃), 29.10, 18.51 (2£CH₃-

isopropylidene), 25.87 (tBu), 23.16, 21.29 (2£CH₃-iPr),

24.18, 24.40 (2£SiCH₃); (CI, NH₃): m/z (%): 542 (100)

[MþNH₄^þ]; HRMS (positive-ion CI, NH₃): calcd for

C₂₇H₄₈O₈NSi (MþNH₄^þ) 542.3149, found 542.3143.

[a]²_D⁰¼2110 (c¼0.3 in CHCl₃); mp 118 8C (n-pentane/ethyl

1

acetate); H NMR (CDCl₃, 400 MHz): d¼5.39 (dd, J¼1.5,

2.8 Hz, 1H, H-1), 4.62 (t, J¼2.8 Hz, 1H, H-2), 4.33 (d,

J¼3.9 Hz, 1H, H-4), 4.17 (d, J¼12.6 Hz, 1H, H-6), 4.10 (m,

J¼6.2 Hz, 1H, H-7), 3.98 (d, J¼12.6 Hz, 1H, H-6⁰), 3.94

(m, 1H, H-3), 3.64 (d, J¼11.9 Hz, 1H, OH), 3.30 (s, 1H,

OH), 1.64 (s, 1H, OH), 1.33 (d, J¼6.2 Hz, 3H, CH₃-iPr),

1.26 (d, J¼6.2 Hz, 3H, CH₃-iPr); ¹³C NMR (CDCl₃,

100 MHz): d¼169.0 (CvO), 95.90 (CH-1), 75.91 (CH-4),

75.15 (CH-3), 73.46 (CH-2), 73.06 (CH-7), 61.94 (CH₂-6),

23.53, 21.57 (2£CH₃-iPr); (CI, NH₃): m/z (%): 266 (100)

[MþNH₄^þ]; HRMS (positive-ion CI, NH₃): calcd for

C₁₀H₁₇O₇(MþH^þ) 249.0974, found 249.0979.

5.2.25. Methyl (3-O-benzyl-4,6-O-benzylidene-2-O,5-C-

methylene-b-^D-glucopyranosyl)-(1,4)-O-2,3,6-tri-O-ben-

zyl-a-^D-glucopyranoside 27. Thiophenyl derivative 11

(110 mg, 0.24 mmol), alcohol 26 (133 mg, 0.29 mmol)

˚

5.2.23. Isopropyl 3-O-benzyl-4,6-O-benzylidene-2-O,5-C-

carbonyl-b-^D-glucopyranoside 25. Tetrabutylammonium

ﬂuoride (190 mg, 0.6 mmol) was added to a solution of

methyl ester derivative 24 (104 mg, 0.2 mmol) in dry THF

(10 mL) under argon and the solution was stirred for 3 h at

rt. The reaction mixture was then poured in ice–water,

extracted with EtOAc, the organic layer was dried over

MgSO₄and concentrated. Puriﬁcation by column chroma-

tography (cyclohexane/EtOAc 9:1) afforded the lactonized

compound 25 (68 mg, 0.18 mmol, 90% yield) as a crystal-

line compound.

and powdered 4 A molecular sieves (350 mg) were

suspended in dry CH₂Cl₂(13 mL) under argon and the

suspension was stirred for 30 min at rt. The reaction mixture

was then cooled to 230 8C, NIS (108 mg, 0.48 mmol)

followed by triﬂic acid (4 mL, 0.036 mmol) were added to

give a red solution. After 15 min of stirring at 230 8C, the

reaction mixture was neutralized with sat. aq. NaHCO₃,

diluted with Et₂O (50 mL), washed with sat. aq. Na₂S₂O₃,

brine, and dried over MgSO₄. Puriﬁcation by column

chromatography (cyclohexane/EtOAc 5:1) afforded the

protected disaccharide 27 (93 mg, 0.114 mmol, 48% yield)

as an oil.

[a]²_D⁰¼274 (c¼2.31 in CHCl₃); mp 91–92 8C (n-pentane/

1

EtOAc); H NMR (CDCl₃, 400 MHz): d¼7.43–7.30 (m,

[a]²_D⁰¼237 (c¼1 in CHCl₃); H RMN (CDCl₃, 400 MHz):

5H, Ph), 5.28 (dd, J¼1.3, 2.8 Hz, 1H, H-1), 4.73 (d, J¼

12.1 Hz, 1H, CHPh), 4.69 (d, J¼12.1 Hz, 1H, CHPh), 4.58

(t, J¼2.8 Hz, 1H, H-2), 4.44 (d, J¼5.0 Hz, 1H, H-4), 4.27

(d, J¼11.8 Hz, 1H, H-6), 4.01 (m, J¼6.2 Hz, 1H, H-7),

3.85 (d, J¼11.8 Hz, 1H, H-6⁰), 3.83 (ddd, J¼1.3, 5.0,

2.8 Hz, 1H, H-3), 1.48 (s, 3H, CH₃-isopropylidene), 1.42 (s,

3H, CH₃-isopropylidene), 1.34 (d, J¼6.2 Hz, 3H, CH₃-iPr),

1.24 (d, J¼6.2 Hz, 3H, CH₃-iPr); ¹³C NMR (CDCl₃,

100 MHz): d¼168.42 (CvO), 137.65 (Cipso), 128.30,

127.78, 127.56 (Ph), 99.65 (C(CH₃)₂), 96.40 (CH-1),

78.90 (CH-3), 72.91 (CH-2), 72.31 (CH-4), 72.17 (CH-7),

72.14 (CH₂Ph), 67.05 (C-5), 60.73 (CH₂-6), 27.94, 19.15

d¼7.48–7,30 (m, 5H, Ph), 5.37 (dd, J¼2.5, 1.1 Hz, 1H,

H-1⁰), 5.07 (s, 2H, CH₂Ph), 4.97 (s, 1H, CHPh), 4.82 (d,

J¼12.3 Hz, 1H, CHPh), 4.71 (d, J¼12.3 Hz, 1H, CHPh),

4.67 (d, J¼12.0 Hz, 1H, CHPh), 4.66 (d, J¼3.4 Hz, 1H,

H-1), 4.64 (d, J¼11.3 Hz, 1H, CHPh), 4.56 (d, J¼12.0 Hz,

1H, CHPh), 4.45 (d, J¼11.3 Hz, 1H, CHPh), 4.29 (d, J¼

9.5 Hz, 1H, H-7), 4.12 (dd, J¼4.8, 1.6 Hz, 1H, H-4⁰), 3.97 (t,

J¼9.1 Hz, 1H, H-3), 3.90 (t, J¼9.2 Hz, 1H, H-4), 3.87 (m,

1H, H-3⁰), 3.76 (d, J¼11.2 Hz, 1H, H-6a⁰), 3.74 (m, J¼

9.4 Hz, 1H, H-5), 3.69 (t, J¼2.6 Hz, 1H, H-2⁰), 3.68 (dd,

J¼3.0, 10.4 Hz, 1H, H-6a), 3.62 (dd, J¼3.4, 9.1 Hz, 1H,

H-2), 3.56 (d, J¼1.9 Hz, 1H, H-6b), 3.55 (dd, J¼1.7,

´

Y. Bleriot et al. / Tetrahedron 60 (2004) 6813–6828

6827

9.5 Hz, 1H, H-7b⁰), 3.46 (d, J¼11.2 Hz, 1H, H-6b⁰), 3.43 (s,

3H, OCH₃); ¹³C RMN (CDCl₃, 400 MHz): d¼139.64,

138.05, 137.98, 137.62, 137.14 (5£Cipso), 129.05–126.03

(5£Ph), 100.6 (CHPh), 100.08 (C-1⁰), 98.27 (C-1), 81.02

(C-4⁰), 80.16 (C-3), 79.21 (C-2), 78.36 (C-3⁰), 76.42 (C-4),

74.76 (CH₂Ph), 73.51 (CH₂Ph), 73.35 (CH₂Ph), 71.35

(CH₂Ph), 69.65 (C-5), 69.61 (C-6⁰), 68.16 (C-6), 66.45

(C-2⁰), 65.66 (C-7⁰), 65.02 (C-5⁰), 55.22 (OCH₃); (CI, NH₃):

m/z (%): 834 (100) [MþNH₄^þ]; C₄₉H₅₂O₁₁(816.95): calcd

C 72.04, H 6.42; found C 71.81, H 6.65.

2. Bennet, A. J.; Kitos, T. E. J. Chem. Soc., Perkin Trans. 2 2002,

1207–1222, and selective relevant references therein.

3. Capon, B. Chem. Rev. 1969, 69, 407–496.

4. Jensen, H. H.; Bols, M. Org. Lett. 2003, 5, 3419–3421.

5. Edward, J. T. Chem. Ind. (London) 1955, 1102–1104.

6. Namchuk, N. M.; McCarter, J. D.; Becalski, A.; Andrews, T.;

Withers, S. G. J. Am. Chem. Soc. 2000, 122, 1270–1277.

7. Dean, K. E. S.; Kirby, A. J.; Komarov, I. V. J. Chem. Soc.,

Perkin Trans. 2 2002, 337–341.

8. Barnes, J. A.; Williams, I. H. Chem. Commun. 1996, 193–194.

9. Bennet, A. J.; Sinnott, M. L. J. Am. Chem. Soc. 1986, 108,

7287–7294.

5.2.26. Methyl (2-O,5-C-methylene-b-^D-glucopyranosyl)-

(1,4)-a-^D-glucopyranoside 28. Disaccharide 27 (25 mg,

0.030 mmol) was dissolved in methanol (5 mL) and 10%

Pd/C (10 mg) was added. The suspension was stirred under

H₂for 1 h at rt, ﬁltered through celite eluted with methanol

and concentrated. Puriﬁcation by column chromatography

(10% CH₃OH in EtOAc) afforded the disaccharide 28

(10 mg, 0.027 mmol, 90% yield) as a foam.

10. Indurugalla, D.; Bennet, A. J. J. Am. Chem. Soc. 2001, 123,

10889–10898.

´

11. For a preliminary communication on this work, see: Bleriot,

Y.; Vadivel, S. K.; Greig, I. R.; Kirby, A. J.; Sinay¨, P.

Tetrahedron Lett. 2003, 44, 6687–6690.

12. Chandrasekhar, S.; Kirby, A. J.; Martin, R. J. J. Chem. Soc.,

Perkin Trans. 2 1983, 1619–1626. Ley, S. V.; Baeschlin,

K. K.; Dixon, D. J.; Foster, A. C.; Ince, S. J.; Priepke, H. W.

M.; Reynolds, D. J. Chem. Rev. 2001, 101, 53–80.

1

[a]²_D⁰¼þ61 (c¼1.05 in H₂O); H RMN (D₂O, 500 MHz):

d¼5.33 (dd, J¼2.7, 1.3 Hz, 1H, H-1⁰), 4.81 ₀(d, J¼3.8 Hz,

1H, H-1), 4.07 (dd, J¼5.2, 1.7 Hz, 1H, H-4 ), 3.98₀(t, J¼

2.7 Hz, 1H, H-2⁰), 3.95 (dd, J¼2.7, 5.2 Hz, 1H, H-3 ), 3.84

(d, J¼12.0 Hz, 1H, H-6a), 3.83 (dd, J¼9.2, 9.8 Hz, 1H,

H-3), 3.85 (d, J¼9.8 Hz, 1H, H-7⁰a), 3.77 (dd, J¼4.5,

12.0 Hz, 1H, H-6b), 3.76 (ddd, J¼4.5, 9.8, 12.0 Hz, 1H,

H-5), 3.73 (d, J¼12.7 Hz, 1H, H-6a⁰), 3.65 (dd, J¼1.7,

9.8 Hz, 1H, H-7b⁰), 3.62 (dd, J¼3.8, 9.8 Hz, 1H, H-2), 3.59

(dd, J¼9.2, 9.8 Hz, 1H, H-4), 3.64 (d, J¼12.7 Hz, 1H,

H-6b⁰), 3.39 (s, 3H, OCH₃); ¹³C RMN (D₂O, 100 MHz):

d¼100.06 (CH-1⁰), ₀99.42 (CH-1), 78.92 (CH-4), 73.33

(C-5⁰), 74.72 (CH-3 ), 73.53 (CH-4⁰), 71.81 (CH-3), 71.78

(CH-2), 70.50 (CH-5), 68.31 (CH-2⁰), 62.22 (CH₂-7⁰), 60.38

(CH₂-6, CH₂-6⁰), 55.39 (OCH₃); (CI, NH₃): m/z (%): 386

(100) [MþNH₄^þ]; HRMS (positive-ion CI, NH₃): calcd for

C₁₄H₂₈O₁₁N (MþNH^þ₄) 386.1662, found 386.1654.

13. Stoddart, J. F. Stereochemistry of Carbohydrates. Wiley-

Interscience: New York, 1971; p 47.

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´

(Centre des Resolutions de Structures, Universite Pierre and

Marie Curie) for solving the crystal structures, Dr R. Nash

(MolecularNature Ltd, IGER, Aberystwyth, Wales) for

performing inhibition tests on commercially available

glycosidases, Dr M. Hrmova (University of Adelaide,

Australia) for the study on barley b-^D-glucan glucohydro-

lase, and Dr K. Piens (University of Gent, Belgium) for

the study on cellobiohydrolases from T. Reesei. A.J.H.

acknowledges the ﬁnancial support provided through the

European Community’s Human Potential Programme under

contract HPRN-CT-2002-00173.

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Article Doi

Synthesis and acid catalyzed hydrolysis of B2,5 type conformationally constrained glucopyranosides: Incorporation into a cellobiose analogue

DOI: 10.1016/j.tet.2004.06.009

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