Lipase-catalysed regioselective acylations in combination with regioselective glycosylations as a strategy for the synthesis of oligosaccharides: Synthesis of a series of fucosyllactose building blocks

Article abstract of DOI:10.1002/ejoc.200200425

A family of five regioisomeric protected fucosyllactoses has been synthesised in only 14 overall steps from the easily available benzyllactoside. The adopted strategy combines enzymatic regioselective protection, introduction of orthogonal protecting grou

Full text of DOI:10.1002/ejoc.200200425

FULL PAPER
Lipase-Catalysed Regioselective Acylations in Combination with Regioselective
Glycosylations as a Strategy for the Synthesis of Oligosaccharides: Synthesis
of a Series of Fucosyllactose Building Blocks
Anna Rencurosi,[a] Laura Poletti,[a] Giovanni Russo,[a] and Luigi Lay*[a]
Keywords: Oligosaccharides / Fucosyllactose / Glycosylation / Lipase acylation
A family of five regioisomeric protected fucosyllactoses has
been synthesised in only 14 overall steps from the easily
available benzyllactoside. The adopted strategy combines
enzymatic regioselective protection, introduction of ortho-
gonal protecting groups and regioselective glycosylations on
partially unprotected lactosidic acceptors.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2003)
Introduction
Human milk is extremely rich in oligosaccharides, more
than 130 different compounds having been isolated and
identified so far.[1,2] The biological significance of these
compounds was largely unappreciated in the past, as they
were thought to be nutritionally irrelevant and merely by-
products due to the presence of glycosyl transferases in the
mammary gland. Recently the great importance of these
compounds for breast-fed infants has been demonstrated;
during the lactation period the oligosaccharides, besides
other biological roles, inhibit bacterial adhesion to the sur-
face of epithelial cells, which has been recognized as a cru-
cial initial step in the infection process.[3]
Recent studies demonstrated that an inhibitory effect on
E. coli adhesion to uroepithelial cells is induced by a frac-
tion of fucose containing low molecular weight human milk
oligosaccharides (HMOs),[4] Fuc-α-(1Ǟ2)-Gal-β-(1Ǟ4)-
Glc and Gal-β-(1Ǟ4)-[Fuc-α-(1Ǟ3)]-Glc being among the
most abundant.[5] In order to establish whether the anti-
adhesion properties of these compounds are merely due to
the presence of fucose or whether glycosylation position
plays a role in determining the bioactivity, we planned to
synthesise a series of regioisomeric fucosyllactoses illus-
trated in Figure 1.[6]
Figure 1. Fucosyllactose series: arrows indicate the fucosylation po-
sitions
and time consuming; (ii) the building-block approach, em-
ployed in many syntheses,[7] relies on orthogonally pro-
tected acceptor precursors, which require the selective de-
protection of each single hydroxyl group followed by its gly-
cosylation; (iii) the ‘‘random glycosylation’’ concept pro-
posed by Hindsgaul[8] (one unprotected acceptor and one
donor) produces mixtures of all the possible regioisomeric
oligosaccharides. However, the latter is only very convenient
if one is interested in testing the mixture itself in a biologi-
cal assay.
In our case, as we needed pure single compounds, the
building-block approach looked the most appealing. We
therefore designed a protected lactosidic building block to
be used as a scaffold to obtain all the target trisaccharides.
One major drawback of the building-block strategy is that
it implies a selective access to each single hydroxyl group,
i.e. the introduction of a proper combination of numerous
orthogonal protecting groups, the manipulation of which
might be anything but easy. Thus, we envisaged a modified
approach based on the combination of two concepts: (i)
synthesis of a lactosidic scaffold containing a minimal num-
ber of orthogonal protecting groups, introduced when pos-
sible by regioselective enzymatic reactions; (ii) regioselective
glycosylations on partially unprotected acceptors, which ex-
ploit the intrinsic differences in reactivity between various
hydroxyl groups arising from steric and electronic effects.
Although regioselective glycosylations allow the shorten-
ing of synthetic protocols, they are generally under-ex-
The synthesis of this small trisaccharide library could be
approached in different ways: (i) the classical target-ori-
ented synthesis, consisting of the independent systematic
preparation of each member of the family, would give the
best results in terms of yield but would be very laborious
[a]
Dipartimento di Chimica Organica
e Industriale, Centro
Interdisciplinare Studi bio-molecolari e applicazioni Industriali
`
(CISI), Universita degli Studi di Milano, and CNR (Istituto di
Scienze e Tecnologie Molecolari),
Via G. Venezian 21, 20133 Milano, Italy
Fax: (internat.) ϩ 39-02/50314062
E-mail: luigi.lay@unimi.it
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DOI: 10.1002/ejoc.200200425
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Synthesis of a Series of Fucosyllactose Building Blocks
FULL PAPER
ploited in oligosaccharide syntheses.[9] In addition, the in- 1c-H signal appeared as a doublet at δ ϭ 5.53 ppm with
troduction of protecting groups by enzymatic acylations[10] 3J1c,2c ϭ 3.3 Hz as expected for a 1,2-cis linkage.
is a highly regioselective transformation also able to
shorten, dramatically, the synthetic pathway. In recent
years, we have reported on the use of lipase-catalysed acyl-
ation for designing useful building blocks for oligosacchar-
ide synthesis.[11] That approach proved to be extremely use-
ful in the present case also. Here, we describe our results in
the application of this ‘‘hybrid’’ strategy to the synthesis of
five protected regioisomeric fucosyllactoses, obtained in
only 14 overall steps from easily available β-benzyllactoside.
Interestingly, a similar strategy could also be envisaged as
a way towards new developments in the combinatorial syn-
thesis of carbohydrate-based libraries.[12]
Results and Discussion
Lactoside 5 was chosen as a key building block in our
strategy. The synthesis of 5 started from β-benzyllacto-
side,[13] which was converted into the orthogonally pro-
Scheme 2. a) NH3NH2OAc, EtOH/Et2O (99%); b) 7, TMSOTf
(0.01eq), Ϫ10 °C (61%); c) TBAF, THF, AcOH, 0 °C (61%); d) 7,
tected compound 2 by a double sequential acylation at 6b-
OH and 2b-OH catalysed by lipase from Candida antarctica
(Scheme 1). The introduction of an isopropylidene acetal at
positions 3b, 4b afforded compound 3. Regioselective 6a-
O-silylation using thexyl dimethylsilyl chloride (TDSCl)[14]
and imidazole in N,N-dimethylformamide gave diol 4 in
75% yield. Benzoylation of the remaining hydroxyl groups
gave the lactose building block 5.
TMSOTf (0.01 equiv.), Ϫ36 °C, (α/β ϭ 2:1, 76%)
The synthesis of protected Gal-β-(1Ǟ4)-[Fuc-α-(1Ǟ6)]-
Glc was achieved through removal of the silyl group of 5
with tetrabutylammonium fluoride (TBAF) in THF at 0 °C
to give 9, followed by glycosylation (DP) with donor 7 at
Ϫ36 °C using TMSOTf as a promoter. Compound 10 was
obtained in 76% yield as a separable 2:1 α/β mixture
(Scheme 2).[18] The structure of the unusual β derivative was
determined by NMR spectroscopy and mass spectrometry:
the 1c-H signal for compound 10β appeared as a doublet at
3
δ ϭ 4.59 ppm with J1c,2c ϭ 7.8 Hz (δ ϭ 5.04 ppm with
3J1c,2c ϭ 3.2 Hz for 10α), confirming the 1,2-trans linkage,
whereas the MALDI-TOF spectra showed the same mass
for both compounds.
For the synthesis of the remaining regioisomers we inves-
tigated the use of regioselective glycosylation reactions.
Most literature data relates to the use of this strategy in
the syntheses of (1Ǟ6)-linked oligosaccharides, where the
marked difference in the reactivity between primary and
secondary hydroxyl groups was exploited.[19] However, vari-
ous examples of regioselective glycosylations of acceptors
containing two or more secondary hydroxyl groups have
been described.[20] In this context, diol 4 was selected as a
direct precursor of Gal-β-(1Ǟ4)-[Fuc-α-(1Ǟ2)]-Glc. Pre-
vious studies indicated the higher reactivity of the 2a-OH
Scheme 1. a) Vinyl acetate, THF, Candida antartica lipase (73%); b)
trifluoroethyl levulinate, CH3CN, Candida antartica lipase (72%); c)
acetone, CSA, sikkon (66%); d) TDSCl, imidazole, DMF (75%); e)
BzCl, Py, DMAP (94%)
The naturally occurring Fuc-α-(1Ǟ2)-Gal-β-(1Ǟ4)-Glc compared to the 3a-OH of lactose in acylation reactions
was synthesised as follows: Acceptor 6 was obtained in and this was also exploited for efficient syntheses of Gal-β-
quantitative yield by chemoselective removal of the 2b-O- (1Ǟ4)-[Fuc-α-(1Ǟ3)]-Glc building blocks.[11e,21] Moreover,
levulinoyl (Lev) group from compound 5 with hydrazinium it is known that the glycosylation of methyl (or benzyl) 4,6-
acetate.[11c,15] A glycosylation reaction by direct procedure O-benzylidene-α--glucopyranoside with 2,3,4,6-tetra-O-
(DP),[16] using the α-trichloroacetimidate of the 3,4 di-O- acetyl-α--glucopyranosyl bromide gives predominantly the
acetyl-2-O-benzyl--fucopyranose 7[17] as a donor and β-(1Ǟ2)-linked disaccharide.[22] These results suggested
TMSOTf as a promoter, afforded trisaccharide 8 in 61% that a similar order of reactivity might be preserved in the
yield (Scheme 2). The stereochemistry at the newly formed glycosylation of diol 4 with the fucosyl donor 7. Gratify-
glycosidic linkage was shown to be α by NMR analysis: the ingly, using the direct procedure at Ϫ30 °C in CH2Cl2 and
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A. Rencurosi, L. Poletti, G. Russo, L. Lay
FULL PAPER
TMSOTf (0.01 equiv.) as a promoter, we obtained α-(1Ǟ2)- was deduced by the 1c-H/2c-H coupling constant value
linked trisaccharide 11 as a single compound in 76% yield (3J1c,2c ϭ 3.7 Hz).
after chromatographic purification, without detection of
the (1Ǟ3)-linked regioisomer (Scheme 3).
Scheme 4. a) TFA, CH2Cl2 (82%); b) 7, TMSOTf (0.01 equiv.),
CH2Cl2 Ϫ30 °C (47%); c) K2CO3, dry MeOH, Ϫ20 °C/-35 °C, 24 h
(83%); d) 7, TMSOTf (0.01 equiv.), CH2Cl2 Ϫ35 °C (51%)
Scheme 3. a) 7, TMSOTf (0.01 equiv.), Ϫ30 °C (76%); b) neat tri-
chloroacetyl isocyanate, room temp., quant.; c) TFA, CH2Cl2, 75%
Straightforward access to Fuc-α-(1Ǟ6)-Gal-β-(1Ǟ4)-Glc
trisaccharide from building block 5 required the difficult
selective removal of the 6b-O-acetate in the presence of
The glycosylation regiochemistry was confirmed by other acyl groups. While discrimination between acetate
NMR spectroscopy by the treatment of 11 with trichlo- and benzoate is in principle possible,[23] this is not true for
roacetyl isocyanate. The NMR spectrum of the obtained acetyl and levulinoyl esters as they show similar behaviour
derivative 11Ј showed a downfield shift of the 3a-H proton under acetate-removal conditions. Therefore, we directed
to δ ϭ 5.25 ppm from δ ϭ 3.87Ϫ3.91 in compound 11, as our efforts to the chemoselective deacetylation of com-
deduced by COSY and HMQC experiments. The α configu- pound 6 to obtain the corresponding diol 15, which should
ration at the newly formed glycosidic linkage was deduced be regioselectively fucosylated at the most reactive primary
by the 1c-H/2c-H coupling constant value (3J1c,2c
ϭ
hydroxyl group (Scheme 4). Disappointingly, when we
3.7 Hz).
treated compound 6 with DBU and methanol in refluxing
The synthesis of Fuc-α-(1Ǟ3)-Gal-β-(1Ǟ4)-Glc trisacch- toluene[25] we were able to isolate compound 15 in only 39%
aride was first attempted using diol 12 as an acceptor, ob- yield. In an attempt to disfavour nucleophilic attack on ben-
tained from 5 by acidic hydrolysis of the isopropylidene ace- zoates, we used tert-butyl alcohol instead of methanol, but
tal (Scheme 3). Both direct (Ϫ25 °C/room temp., CH2Cl2, observed no reaction. Treating 6 with methanol and
TMSOTf) and inverse (0 °C/room temp., CH3CN, SnOTf) AcCl[26] at 0 °C afforded only degradation by-products.
procedures afforded an inseparable mixture of two trisacch- Eventually, we found the best conditions to be the treat-
arides in very poor yield. We conjectured that the presence ment of lactoside 6 with anhydrous K2CO3 in dry methanol
of an electron-withdrawing group at the 2b-OH greatly re- at Ϫ20 °C.[27] The reaction proceeded slowly to afford com-
duced the reactivity of the 3b-OH, thus rendering the 4b- pound 15, but after 5 h we observed the formation of lower
OH competitive for the glycosylation. Therefore compound migrating by-products arising from partial concomitant hy-
6 was submitted to acidic hydrolysis to give acceptor 13 drolysis of benzoate esters. We noticed that lowering the
(Scheme 4). This kind of triol has been shown to be ex- reaction temperature to Ϫ35 °C stopped this side-reaction
tremely useful for regioselective sialylation reactions,[11a,22] while the formation of compound 15 continued. After 24 h,
but, to the best of our knowledge, there are no examples compound 15 was recovered in a very good yield (83%).
regarding fucosylation. The reaction was performed at Ϫ30 Fucosylation of diol 15 was accomplished employing the
°C in CH2Cl2, with TMSOTf as a promoter. Trisaccharide direct procedure at Ϫ35 °C in CH2Cl2 using TMSOTf as a
14 was recovered in 47% yield, together with some less po- promoter to afford trisaccharide 16 in 51% yield, with no
lar products, probably tetrasaccharides, which were not iso- other regio- or stereoisomer detected (Scheme 4). The struc-
lated or characterised (Scheme 4). The structure of com- ture of compound 16 was ascertained by NMR spec-
pound 14 was determined by NMR spectroscopy: the C-3b troscopy: the 1c-H signal appeared as a doublet at δ ϭ 4.52
3
signal appeared at δ ϭ 83.1 ppm as evidenced by HMQC ppm with J1c,2c ϭ 3.4 Hz, confirming the 1,2-cis linkage.
experiment, shifted downfield with respect to the corre- The regiochemistry of glycosylation was confirmed by the
sponding signal in compound 13 (δ Յ 75.6, see Exp. Sect.) analysis of 13C NMR spectra: the C-6b signal appeared at
thus confirming the regiochemistry of the glycosylation. δ ϭ 63.9 ppm, shifted downfield with respect to the corre-
The α configuration at the newly formed glycosidic linkage sponding signal in compound 15 (δ ϭ 61.7/61.8), whereas
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Synthesis of a Series of Fucosyllactose Building Blocks
FULL PAPER
chromatography was performed by the flash procedure using
Merck silica gel 60 (230Ϫ400 mesh). Elemental analyses were per-
formed using the Carlo Erba elemental analyser 1108. Solvents
were dried by standard procedures.
the C-2b chemical shift (δ ϭ 74.0 ppm) is similar to the
corresponding signal in 15 (δ ϭ 73.9/74.0). As an illustra-
tive example of the feasibility of our synthetic approach,
compound 16 was deprotected as follows (Scheme 5). First,
desilylation at position 6a was achieved by using a 1  solu-
Benzyl (6-O-Acetyl-β-D-galactopyranosyl)-(1Ǟ4)-β-D-glucopyrano-
tion of TBAF in THF; thereafter treatment with 70% aque- side (1): Benzyl β--lactoside[12] (5.05 g, 11.7 mmol) was suspended
in dry THF (500 mL). Vinyl acetate (150 mL, 1.62 mol) and Can-
dida antarctica lipase (15.1 g) were added, the suspension was
mechanically stirred for 2 days at 40 °C and monitored by TLC
(EtOAc/MeOH/H2O, 8:1.5:0.5). The enzyme was filtered off and
the solvent was removed under reduced pressure. Purification by
flash chromatography (EtOAc/MeOH, 10:1) afforded compound 1
as a white foam (3.92 g, 73%). Optical rotation value and NMR
spectroscopic data are in agreement with those previously re-
ported.[28]
ous trifluoroacetic acid led to hydrolysis of the isopropylid-
ene acetal, affording trisaccharide 17 in 67% overall yield.
´
Compound 17 was then submitted to Zemplen deacylation
to remove acetyl and benzoyl esters (85%), furnishing inter-
mediate 18. Hydrogenolysis of the remaining benzyl ethers,
using Pd/C as a catalyst, eventually provided trisaccharide
19 (75%).
Benzyl (6-O-Acetyl-2-O-levulinoyl-β-D-galactopyranosyl)-(1Ǟ4)-β-
D-glucopyranoside (2): Compound 1 (3.06 g, 6.50 mmol) was sus-
pended in CH3CN (200 mL). Trifluoroethyl levulinate (48.5 mL,
245 mmol) and Candida antarctica lipase (9.30 g) were added, the
suspension was stirred with a mechanical stirrer for 4 days at 45
°C and monitored by TLC (EtOAc/MeOH/H2O, 8:1.5:0.5). The en-
zyme was filtered off and the solvent was removed under reduced
pressure. Purification by flash chromatography (EtOAc/MeOH,
10:0.5) afforded unchanged compound 1 (0.57 g, 18%) and com-
pound 2 (2.66 g, 72%) as a white foam. [α]2D0 ϭ ϩ15.7 (c ϭ 0.8,
CHCl3). 1H NMR (300 MHz, CD3OD): δ ϭ 2.10 (s, 3 H, COCH3),
2.20 (s, 3 H, CH3COCH2), 2.73Ϫ2.77 [m, 4 H, (CH2)2CO], 3.30
(m, 1 H, 2a-H), 3.39 (ddd, 3J5,6Ј ϭ 1.8, 3J5,6Ј ϭ 4.0, 3J4,5 ϭ 9.0 Hz,
Scheme 5. a) TBAF 1 in THF, dry THF, 40 °C, then 70% aq.
TFA, 0 °C, CH2Cl2 (67%); b) MeONa, MeOH, room temp. (85%);
c) H2, Pd/C, MeOH, room temp. (75%)
3
1 H, 5a-H), 3.52 (m, 2 H, 3a-H, 4a-H), 3.69 (dd, J3,4 ϭ 3.4 Hz, 1
2
H, 3b-H), 3.74 (dd, J6,6Ј ϭ 8.3 Hz, 1 H, 6a-H), 3.87 (m, 3 H, 4b-
3
H, 5b-H, 6Јa-H), 4.24 (dd, J6,5 ϭ 4.5 Hz, 1 H, 6b-H), 4.31 (dd,
3
3
2J6,6Ј ϭ 11.6, J6,5 ϭ 8.1 Hz, 1 H, 6Јb-H), 4.39 (d, J1,2 ϭ 7.7 Hz,
3
1 H, 1a-H), 4.58 (d, J1,2 ϭ 8.0 Hz, 1 H, 1b-H), 4.66 (d, 1 H,
CHHPh), 4.91 (d, J ϭ 11.8 Hz, 1 H, CHHPh), 5.05 (dd, J2,3
Conclusion
2
3
ϭ
9.9 Hz, 1 H, 2b-H), 7.20Ϫ7.35 (m, 5 H, C6H5) ppm. 13C NMR
(75.44 MHz, CD3OD): δ ϭ 21.0 (COCH3), 29.3 (CH2COO), 30.0
(CH2COCH3), 38.8 (CH2COCH3), 62.0, 65.0 (6a-C, 6b-C), 72.1
(CH2Ph), 70.6, 73.2, 74.7, 75.1, 76.6, 81.6 (2a-C, 3a-C, 4a-C, 5a-C,
2b-C, 3b-C, 4b-C, 5b-C, overlapped signals), 102.9, 103.4 (1a-C,
1b-C), 173.0, 174.1 (2 CH3CO), 209.9 (CH2COCH3) ppm.
C26H36O14 (572.55): calcd. C 54.54, H 6.34; found C 54.41, H 6.30.
In conclusion, five regioisomeric protected fucosyl-
lactoses have been prepared in only 14 overall steps from
the easily available benzyllactoside, by adopting an efficient
protocol which combines enzymatic regioselective protec-
tion, orthogonal protecting group strategy and regioselec-
tive glycosylations on partially unprotected acceptors. The
synthesised trisaccharides together with compound Gal-β-
(1Ǟ4)-[Fuc-α-(1Ǟ3)]-Glc already available in our labora-
tory[11d] will be deprotected and submitted to antiadhesion
biological assays.
Benzyl (6-O-Acetyl-3,4-O-isopropylidene-2-O-levulinoyl-β-
D-galac-
topyranosyl)-(1Ǟ4)-β- -glucopyranoside (3): Compound 2 (2.00 g,
D
3.49 mmol) was dissolved in dry acetone (150 mL) under an inert
atmosphere, sikkon (2.50 g) was added and the mixture was stirred
for 30 min. A catalytic amount of camphorsulfonic acid was added
and the suspension was refluxed for 22 h, monitoring the reaction
by TLC (EtOAc/MeOH, 9.5:0.5). After cooling to room tempera-
ture, the mixture was neutralised with TEA, sikkon was filtered off
and the solvent removed under reduced pressure. Purification by
flash chromatography (EtOAc) afforded compound 3 (1.42 g, 66%)
Experimental Section
General: 1H NMR and 13C NMR spectra were recorded on Varian
Gemini 200, Bruker AC 300 and Bruker Avance 400 spectrometers
at 298 K. When required for unambiguous characterisation (com-
1
as a white amorphous solid. [α]2D0 ϭ ϩ31.5 (c ϭ 1.27, CHCl3). H
pounds 8, 10α, 10β, 11, 11Ј, 14, 16؊19), COSY, TOCSY and NMR (200 MHz, CDCl3, few drops of D2O): δ ϭ 1.31 (s, 3 H,
HMQC spectra were also recorded. In descriptions of the 13C spec-
tra, signals corresponding to aromatic carbons are omitted.
MALDI-TOF spectra were carried out on a Bruker Biflex III time-
CH3CCH3), 1.54 (s, 3 H, CH3CCH3), 2.11, 2.19 (2 s, 6 H, 2
COCH3), 3.00Ϫ2.47 [m, 4 H, (CH2)2CO], 3.38Ϫ3.65 (m, 4 H, 2a-
3
H, 3a-H, 4a-H, 5a-H), 3.70 (dd, J5,6 ϭ 3.2 Hz, 1 H, 6a-H), 3.89
2
3
of-flight mass spectrometer. Optical rotations were measured at (dd, J6,6Ј ϭ 12.2, J5,6 ϭ 2.9 Hz, 1 H, 6Јa-H), 4.04Ϫ4.42 (m, 5 H,
3
room temperature with a PerkinϪElmer 241 polarimeter. TLC was
carried out on Merck silica gel 60 F254 plates (0.25 mm thickness),
and spots were visualised by spraying with a solution containing
6b-H, 6Јb-H, 3b-H, 4b-H, 5b-H), 4.44 (d, J1,2 ϭ 7.7 Hz, 1 H, 1a-
3
H), 4.48 (d, J1,2 ϭ 7.8 Hz, 1 H, 1b-H), 4.65 (d, 1 H, CHHPh),
2
3
4.90 (d, J ϭ 11.8 Hz, 1 H, CHHPh), 4.98 (t, J2,3 ϭ 7.3 Hz, 1 H,
H2SO4 (31 mL), ammonium molybdate (21 g) and Ce(SO4)2 (1 g) 2b-H), 7.23Ϫ7.42 (m, 5 H, C6H5) ppm. C29H40O14 (612.62): calcd.
in water (500 mL), followed by heating at 110 °C for 5 min. Column
C 56.86, H 6.58; found C 56.72, H 6.55.
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A. Rencurosi, L. Poletti, G. Russo, L. Lay
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Benzyl (6-O-Acetyl-3,4-O-isopropylidene-2-O-levulinoyl-β-
D-galac-
Benzyl
(6-O-Acetyl-3,4-O-isopropylidene-β-
D-galactopyranosyl)-
topyranosyl)-(1Ǟ4)-6-O-thexyldimethylsilyl-β-
D
-glucopyranoside
(1Ǟ4)-2,3-di-O-benzoyl-6-O-thexyldimethylsilyl-β-D
-glucopyra-
(4): Compound 3 (1.27 g, 2.07 mmol) and imidazole (420 mg,
6.17 mmol) were dissolved in dry DMF (8.0 mL) under an inert
atmosphere. The solution was cooled to 0 °C, TDSCl (500 µL,
noside (6): Compound 5 (203 mg, 0.210 mmol) was dissolved in
EtOH/Et2O (1:1 v/v, 4.0 mL) under Ar atmosphere, then dry
AcONH3NH2 (92.0 mg, 0.240 mmol) was added and the reaction
2.55 mmol) was added dropwise and the reaction mixture was mixture was stirred at room temperature. After 2 h (HPTLC tolu-
stirred for 2 h at room temperature (TLC EtOAc/petroleum ether,
8:2). The solvent was removed under reduced pressure, and the resi-
due was diluted with EtOAc (20.0 mL) and washed first with satd.
NH4Cl, then with water. The organic phase was separated, dried
over Na2SO4, filtered and concentrated. Flash chromatography
purification (EtOAc/petroleum ether, 4:6) afforded 4 (1.18 g, 75%)
ene/EtOAc, 8:2) the solvent was removed under reduced pressure
and purification by flash chromatography (toluene/EtOAc, 8:2) af-
forded compound 6 as a white amorphous solid (181 mg, 99%). [α]
20
1
ϭ ϩ47.8 (c ϭ 1.13, CHCl3). H NMR (200 MHz, CDCl3): δ ϭ
D
0.18, 0.22 [2s, 6 H, Si(CH3)2], 0.93 [m, 12 H, C(CH3)2CH(CH3)2],
1.25 (s, 3 H, CH3CCH3), 1.38 (s, 3 H, CH3CCH3), 1.65 [m, 1 H,
C(CH3)2CH(CH3)2], 2.05 (s, 3 H, COCH3), 2.60 (s, 1 H, OH), 3.49
1
as a white amorphous solid. [α]2D0 ϭ ϩ21.6 (c ϭ 1.0, CHCl3). H
NMR (200 MHz, CDCl3): δ ϭ 0.13, 0.15 [2 s, 6 H, Si(CH3)2],
0.84Ϫ0.95 [m, 12 H, C(CH3)2CH(CH3)2], 1.35 (s, 3 H, CH3CCH3), 4.00 (m, 5 H, 6Јa-H, 3b-H, 4b-H, 6b-H, 6Јb-H), 4.22 (t, J4,5
1.55 (s, 3 H, CH3CCH3), 1.62 [m, 1 H, C(CH3)2CH(CH3)2], 2.11,
(m, 1 H, 2b-H), 3.52 (m, 2 H, 5a-H, 6a-H), 3.69 (m, 1 H, 5b-H),
3
ϭ
9.4 Hz, 1 H, H-4), 4.38 (d, 3J1,2 ϭ 8.2 Hz, 1 H, 1b-H), 4.65 (d, 2J ϭ
2.18 (2 s, 6 H, 2 COCH3), 2.55Ϫ3.00 [m, 4 H, (CH2)2CO], 12.4 Hz, 1 H, CHHPh), 4.75 (d, 1 H, 1a-H), 4.87 (d, 1 H, CHHPh),
3.31Ϫ3.65 (m, 4 H, 2a-H, 3a-H, 4a-H, 5a-H), 3.86 (apparent d, 2 5.42 (t, 3J1,2 ϭ 9.4 Hz, 1 H, 2a-H), 5.58 (t, 3J2,3 ϭ 3J3,4 ഠ 9.4 Hz, 1
H, 6a-H, 6Јa-H), 3.95Ϫ4.22 (m,
3
H, 3b-H, 4b-H, 5b-H), H, 3a-H), 7.10Ϫ8.00 (m, 15 H, 3 C6H5) ppm. C46H60O14Si (865.05):
calcd. C 63.87, H 6.99; found C 63.78, H 6.96.
4.22Ϫ4.45 (m, 3 H, 1a-H, 6b-H, 6Јb-H), 4.48 (d, 1 H, 1b-H), 4.61
(d, 1 H, CHHPh), 4.88 (d, 2J ϭ 11.6 Hz, 1 H, CHHPh), 5.02 (t,
3J1,2 ϭ 3J2,3 ഠ 7.2 Hz, 1 H, 2b-H), 7.25Ϫ7.45 (m, 5 H, C6H5) ppm.
13C NMR (75.44 MHz, CDCl3): δ ϭ Ϫ3.1, Ϫ3.5 [Si(CH3)2],
18.6Ϫ20.7 [C(CH3)2CH(CH3)2, COCH3], 23.8 [C(CH3)2CH-
(CH3)2], 26.1, 27.3 [C(CH3)2], 27.7 (CH2COO), 29.6 (CH3COCH2),
34.3 [C(CH3)2CH(CH3)2], 37.7 (CH3COCH2), 61.3, 63.0 (6a-C, 6b-
C), 70.7 (CH2Ph), 71.1, 72.6, 73.2, 73.9, 74.4, 74.8, 76.9, 80.1 (2a-
C, 3a-C, 4a-C, 5a-C, 2b-C, 3b-C, 4b-C, 5b-C), 100.8, 101.1 (1a-C,
1b-C), 111.0 [C(CH3)2], 170.8, 171.2 (CH3COO, CH2COO), 205.8
(CH3COCH2) ppm. C37H58O14Si (754.93): calcd. C 58.87, H 7.74;
found C 58.96, H 7.78.
Benzyl (3,4-Di-O-acetyl-2-O-benzyl-α-
O-acetyl-3,4-isopropylidene-β- -galactopyranosyl)-(1Ǟ4)-2,3-di-O-
benzoyl-6-O-thexyldimethylsilyl-β- -glucopyranoside (8): Com-
L-fucopyranosyl)-(1Ǟ2)-(6-
D
D
pound 6 (65.0 mg, 75.0 µmol) and fucosyl donor 7[17] (79.0 mg,
0.163 mmol) were dissolved in dry CH2Cl2 (500 µL) and cooled to
Ϫ10 °C. A 0.05  TMSOTf soln in dry CH2Cl2 (15.0 µL, 0.750
µmol) was added dropwise with vigorous stirring (TLC acetone/
toluene, 2:8). After 10 min, the mixture was neutralised with TEA
and concentrated. Flash chromatography purification (acetone/
toluene, 0.5:10) afforded 8 (55.0 mg, 61%) as a white foam. [α]2D0
ϭ
1
Ϫ40.6 (c ϭ 0.97, CHCl3). H NMR (400 MHz, CDCl3): δ ϭ 0.15,
0.22 [2s, 6 H, Si(CH3)2], 0.89 [s, 6 H, C(CH3)2CH(CH3)2], 0.93 [d,
Benzyl (6-O-Acetyl-3,4-O-isopropylidene-2-O-levulinoyl-β-
topyranosyl)-(1Ǟ4)-2,3-di-O-benzoyl-6-O-thexyldimethylsilyl-β-
D-galac-
3
3J ϭ 6.1 Hz, 3 H, C(CH3)2CH(CH3)(CH3)], 0.95 [d, J ϭ 6.1 Hz,
D
-
3
glucopyranoside (5): BzCl (620 µL, 5.34 mmol) was added to a solu-
tion of compound 4 (730 mg, 0.970 mmol) in pyridine (8.0 mL) at
0 °C. The reaction mixture was stirred at room temperature for 2 h
(TLC petroleum ether/EtOAc, 1:1). After quenching excess BzCl
with MeOH, solvents were removed under reduced pressure. The
residue was diluted with CH2Cl2 and washed sequentially with 5%
aq HCl, satd. NaHCO3 and water. The organic phase was sepa-
rated, dried over Na2SO4, filtered and concentrated. Flash chroma-
tography purification (petroleum ether/EtOAc, 6.5:3.5) afforded 5
(880 mg, 94%) as a white amorphous solid. [α]2D0 ϭ ϩ37.5 (c ϭ 1.0,
CHCl3). 1H NMR (300 MHz, CDCl3): δ ϭ 0.18, 0.21 [(2s, 6 H,
Si(CH3)2], 0.93 [m, 12 H, C(CH3)2CH(CH3)2], 1.25 (s, 3 H,
3 H, C(CH3)2CH(CH3)(CH3)], 1.21 (d, J5,6 ϭ 6.5 Hz, 3 H, 6c-H),
1.25 (s, 3 H, CH3CCH3), 1.34 (s, 3 H, CH3CCH3), 1.63 [m, 1 H,
C(CH3)2CH(CH3)2], 1.99 (s, 3 H, COCH3), 2.02, 2.12 (2 s, 6 H,
COCH3), 3.43 (br. d, 1 H, 5a-H), 3.55 (m, 2 H, 6a-H, 2b-H), 3.78
3
(ddd, J5,6 ϭ 3.9, 3J5,6 ϭ 7.8 Hz, 1 H, 5b-H), 3.88 (dd, 1 H, 2c-H),
3
3
3.95 (dd, J3,4 ϭ 5.5, J4,5 ϭ 2.1 Hz, 1 H, 4b-H), 4.01Ϫ4.14 (m, 4
H, 6Јa-H, 3b-H, 6b-H, 6Јb-H), 4.27 (t, 3J3,4 ϭ 3J4,5 ഠ 9.6 Hz, 1 H,
4a-H), 4.41 (br. q, J5,6 ϭ 6.4 Hz, 1 H, 5c-H), 4.57 (d, J1,2
3
3
ϭ
2
8.2 Hz, 1 H, 1b-H), 4.68 (d, 1 H, CHHPh), 4.71 (d, J ϭ 12.2 Hz,
1 H, CHHPh), 4.72 (d, 1 H, 1a-H), 4.87 (d, 2J ϭ 12.6 Hz, 1 H,
3
3
CHHPh), 5.27 (dd, J2,3 ϭ 10.4, J3,4 ϭ 3.4 Hz, 1 H, 3c-H), 5.30
(br. d, 4c-H), 5.42 (dd, J1,2 ϭ 7.7, J2,3 ϭ 10.0 Hz, 1 H, 2a-H),
3
3
3
3
CH3CCH3), 1.38 (s,
3
H, CH3CCH3), 1.65 [m,
1
H,
5.50 (t, J2,3 ϭ J3,4 ഠ 9.6 Hz, 1 H, 3a-H), 5.53 (d, J1,2 ϭ 3.3 Hz,
1 H, 1c-H), 7.19Ϫ7.98 (m, 20 H, 4 C6H5) ppm. 13C NMR
(100.62 MHz, CDCl3): δ ϭ Ϫ2.6, Ϫ3.0 [Si(CH3)2], 15.6 (6c-C),
18.9Ϫ21.3 [C(CH3)2CH(CH3)2, 3 COCH3], 27.6, 26.3 [C(CH3)2],
25.6 [C(CH3)2CH(CH3)2], 34.6 [C(CH3)2CH(CH3)2], 60.9, 63.7 (6a-
C, 6b-C), 72.3, 73.4 (2 CH2Ph), 64.9, 70.5, 71.5, 72.3, 72.3, 73.1,
73.8, 74.2, 75.2, 76.2, 77.4, 80.2 (2a-C, 3a-C,4a-C, 5a-C, 2b-C, 3b-
C, 4b-C, 5b-C, 2c-C, 3c-C, 4c-C, 5c-C), 95.2, 99.6, 100.0 (1a-C,
1b-C, 1c-C), 110.8 [C(CH3)2], 162.86, 165.7, 166.3, 170.6, 171.1 (3
CH3COO, 2 C6H5COO) ppm. C63H80O20Si (1185.38): calcd. C
63.83, H 6.80; found C 63.88, H 6.77.
C(CH3)2CH(CH3)2], 2.08, 2.26 (2 s, 6 H, 2 COCH3), 2.53Ϫ2.88 [m,
4 H, (CH2)2CO], 3.55 (m, 2 H, 5a-H, 6a-H), 3.75 (m, 1 H, 5b-H),
3.92Ϫ4.08 (m, 5 H, 6Јa-H, 3b-H, 4b-H, 6b-H, 6Јb-H), 4.13 (t, 1 H,
2
4a-H), 4.59 (d, 1 H, 1b-H), 4.62 (d, J ϭ 11.6 Hz, 1 H, CHHPh),
3
4.70 (d, 1 H, 1a-H), 4.78 (t, J1,2
ϭ
3J2,3 ഠ 7.9 Hz, 1 H, 2b-H),
3
4.86 (d, 1 H, CHHPh), 5.36 (dd, J1,2 ϭ 7.7 Hz, 1 H, 2a-H), 5.56
(t, 3J2,3 ϭ 3J3,4 ഠ 9.5 Hz, 1 H, 3a-H), 7.10Ϫ8.12 (m, 15 H, 3 C6H5)
ppm. 13C NMR (75.44 MHz, CDCl3): δ ϭ Ϫ3.0, Ϫ3.5 [Si(CH3)2],
18.5Ϫ20.8 [C(CH3)2CH(CH3)2, COCH3], 25.0 [C(CH3)2-
CH(CH3)2], 26.2, 27.3 [C(CH3)2], 27.7 (CH2COO), 29.8
(CH3COCH2), 34.3 [C(CH3)2CH(CH3)2], 37.8 (CH3COCH2), 60.1,
63.0 (6a-C, 6b-C), 70.1 (CH2Ph), 71.0, 72.2, 73.0, 73.3, 73.5, 74.1,
75.5, 77.1 (2a-C, 3a-C, 4a-C, 5a-C, 2b-C, 3b-C, 4b-C, 5b-C), 99.3,
Benzyl (6-O-Acetyl-3,4-O-isopropylidene-2-O-levulinoyl-β-
topyranosyl)-(1Ǟ4)-2,3-di-O-benzoyl-β- -glucopyranoside
D
-galac-
D
(9):
99.6 (1a-C, 1b-C), 110.6 [C(CH3)2], 165.7, 165.3, 171.0, (CH3COO, Compound 5 (200 mg, 0.210 mmol) was dissolved in dry THF
CH2COO, 2 C6H5COO overlapping signals), 206.2 (CH3COCH2). (3.5 mL) under Ar atmosphere, and cooled to 0 °C. A 1.0  solu-
C51H66O16Si (963.15): calcd. C 63.60, H 6.91; found C 63.52, H tion of glacial AcOH in THF (230 µL, 0.230 mmol) and a 1.0 
6.88.
solution of TBAF in THF (450 µL, 0.450 mmol) were added
1676
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 1672Ϫ1680

Synthesis of a Series of Fucosyllactose Building Blocks
FULL PAPER
10β: Amorphous white solid. [α]2D0 ϭ Ϫ24.2 (c ϭ 0.80, CHCl3). H
1
sequentially and the reaction mixture was stirred at room tempera-
ture. After 42 h (TLC, EtOAc) the reaction mixture was diluted NMR (300 MHz, CDCl3): δ ϭ 1.18 (d, J5,6 ϭ 6.3 Hz, 3 H, 6c-H),
3
with EtOAc and washed with satd. NaCl. The organic phase was
separated, dried over anhydrous Na2SO4, filtered and concentrated
at reduced pressure. Flash chromatography purification of the
crude residue (petroleum ether/EtOAc 1:1, then EtOAc) afforded
compound 9 as a white foam (104 mg, 61%). [α]2D0 ϭ ϩ47.0 (c ϭ
1.38 (s, 3 H, CH3CCH3), 1.42 (s, 3 H, CH3CCH3), 1.94, 1.98, 2.12,
2.18 (4 s, 12 H, 3 CH3CO, CH3COCH2), 2.42Ϫ2.92 [m, 4 H,
(CH2)2CO], 3.56Ϫ3.88 (m, 6 H, 5a-H, 5b-H, 6b-H, 6Јb-H, 2c-H,
3
3
5c-H), 3.96 (dd, J3,4 ϭ 5.5, J4,5 ϭ 1.6 Hz, 1 H, 4b-H), 4.04 (m, 2
3
H, 6Јa-H, 3b-H), 4.25 (t, J3,4
ϭ
3J4,5 ϭ 9.5 Hz,1 H, 4a-H), 4.32
0.96, CHCl3). 1H NMR (300 MHz, CDCl3,): δ ϭ 1.23 (s, 3 H, (dd, J6,6Ј ϭ 10.9, J6,5 ϭ 2.4 Hz, 1 H, 6a-H), 4.59 (d, J1,2
ϭ
2
3
3
CH3CCH3), 1.41 (s, 3 H, CH3CCH3), 2.20, 2.02 (2 s, 6 H, 2
7.8 Hz, 1 H, 1c-H), 4.64 (d, 1 H, CHHPh), 4.68 (d, 1 H, 1b-H),
3
3
COCH3), 2.37 (OH), 2.45Ϫ2.95 [m, 4 H, (CH2)2CO], 3.54 (dd, 4.69 (d, 1 H, CHHPh), 4.74 (d, 1 H, 1a-H), 4.78 (t, J1,2 ϭ J2,3
ഠ
3
2J6,6Ј ϭ 11.4, J6,5 ϭ 6.8 Hz, 1 H, 6a-H), 3.63Ϫ3.72 (m, 2 H, 5a-
7.9 Hz, 1 H, 2b-H), 4.84 (d, 2J ϭ 12.5 Hz, 1 H, CHHPh), 4.98 (dd,
H, 5b-H), 3.82Ϫ4.07 (m, 5 H, 6Јa-H, 3b-H, 4b-H, 6b-H, 6Јb-H), 3J2,3 ϭ 6.6, 3J3,4 ϭ 3.5 Hz, 1 H, 3c-H), 5.03 (d, J ϭ 11.4 Hz, 1 H,
2
3
3
4.10 (t, J4,5 ϭ 9.5 Hz, 1 H, 4a-H), 4.51 (d, J1,2 ϭ 7.3 Hz, 1 H, CHHPh), 5.22 (d, 3J3,4 ϭ 3.3 Hz, 1 H, 4c-H), 5.43 (dd, 3J1,2 ϭ 7.9,
1b-H), 4.68 (d, 1 H, CHHPh), 4.76 (d, J1,2 ϭ 7.8 Hz, 1 H, 1a-H), 3J2,3 ϭ 9.6 Hz, 1 H, 2a-H), 5.55 (t, 3J2,3 ϭ 3J3,4 ϭ 9.5 Hz, 1 H, 3a-
3
4.82 (t, 3J
ϭ 7.0 Hz, 1 H, 2b-H), 4.88 (d, 2J ϭ 12.5 Hz, 1 H,
H), 7.09Ϫ8.01 (m, 20 H, 4 C6H5) ppm. 13C NMR (100.62 MHz,
CDCl3): δ ϭ 16.4 (6c-C), 20.6, 20.7 (3 CH3COO overlapping sig-
2,3
CHHPh), 5.42 (t, 3J2,3 ϭ 8.0 Hz, 1 H, 2a-H), 5.60 (t, 3J2,3 ϭ 3J3,4
ഠ
9.6 Hz, 1 H, 3a-H), 7.15Ϫ7.98 (m, 15 H, 3 C6H5) ppm. 13C NMR nals), 26.3, 27.4 [C(CH3)2], 27.7 (CH2COO), 29.9 (CH3COCH2),
(75.44 MHz, CDCl3): δ ϭ 20.8 (CH3COO). 26.1, 27.3 [C(CH3)2],
37.8 (CH3COCH2), 62.8, 66.6 (6a-C, 6b-C), 68.9, 70.6, 70.7, 72.0,
27.7 (CH2COO), 29.9 (CH3COCH2), 37.7 (CH3COCH2), 60.9, 62.6 72.6, 72.9, 73.3, 73.4, 73.8, 74.3, 76.3, 77.2 (2a-C, 3a-C, 4a-C, 5a-
(6a-C, 6b-C), 70.8 (CH2Ph), 70.6, 72.1, 73.0, 73.4, 75.2, 75.4, 77.0
C, 2b-C, 3b-C, 4b-C, 5b-C, 2c-C, 3c-C, 4c-C, 5c-C), 70.2, 74.6 (2
(2a-C, 3a-C, 4a-C, 5a-C, 2b-C, 3b-C, 4b-C, 5b-C, overlapping sig-
CH2Ph), 99.2, 99.5, 103.5 (1a-C, 1b-C, 1c-C), 110.6 [C(CH3)2],
nals), 99.6, 100.4 (1a-C, 1b-C), 110.6 [C(CH3)2], 165.3, 165.4, 170.4, 165.2, 165.6, 170.1, 170.4, 171.0 (3 CH3COO, CH2COO, 2
171.2 (CH3COO, CH2COO, 2 C6H5COO), 206.8 (CH3COCH2) C6H5COO overlapping signals), 206.4 (CH3COCH2) ppm.
ppm. C43H48O16 (820.83): calcd. C 62.92, H 5.89; found C 62.88,
H 5.91.
MALDI-TOF MS: m/z ϭ 1163.21 [M ϩ Naϩ], 1179.18 [M ϩ Kϩ].
C60H68O22 (1141.69): calcd. C 63.15, H 6.01; found C 63.19, H
6.04.
Benzyl (6-O-Acetyl-3,4-O-isopropylidene-2-O-levulinoyl-β-
topyranosyl)-(1Ǟ4)-[(3,4-di-O-acetyl-2-O-benzyl-α- -fucopyrano-
syl)-(1Ǟ6)]-2,3-di-O-benzoyl-β- -glucopyranoside (10α) and Benzyl
(6-O-Acetyl-3,4-O-isopropylidene-2-O-levulinoyl-β- -galactopyra-
nosyl)-(1Ǟ4)-[(3,4-di-O-acetyl-2-O-benzyl-β- -fucopyranosyl)-
(1Ǟ6)]-2,3-di-O-benzoyl-β- -glucopyranoside (10β): Compound 9
D-galac-
L
Benzyl (6-O-Acetyl-3,4-O-isopropylidene-2-O-levulinoyl-β-
topyranosyl)-(1Ǟ4)-[(3,4-di-O-acetyl-2-O-benzyl-α- -fucopyra-
nosyl)-(1Ǟ2)]-6-O-thexyldimethylsilyl-β- -glucopyranoside (11):
Compound
(49.0 mg, 65.0 µmol) and fucosyl donor 7[17]
D-galac-
D
L
D
D
L
4
D
(47.0 mg, 97.0 µmol) were dissolved in dry CH2Cl2 (500 µL) and
cooled to Ϫ30 °C. A 0.05  TMSOTf solution in dry CH2Cl2 (13.0
µL, 0.650 µmol) was added dropwise with vigorous stirring
(HPTLC toluene/EtOAc, 6:4). After 10 min the reaction mixture
was neutralised with TEA and concentrated. Flash chromatogra-
phy purification (toluene/EtOAc, 8:2) of the crude residue afforded
11 (53.0 mg, 76%) as a white foam. [α]2D0 ϭ Ϫ41.6 (c ϭ 1.0, CHCl3).
1H NMR (400 MHz, CDCl3): δ ϭ 0.17, 0.18 [2s, 6 H, Si(CH3)2],
(50.0 mg, 61.0 µmol) and fucosyl donor 7[17] (59.0 mg, 122 µmol)
were dissolved in dry CH2Cl2 (400 µL) and cooled to Ϫ36 °C. A
0.05  TMSOTf solution in dry CH2Cl2 (12.0 µL, 0.610 µmol) was
added dropwise with vigorous stirring (HPTLC toluene/ EtOAc,
6:4). After 15 min the reaction mixture was neutralised with TEA
and concentrated. Flash chromatography purification (toluene/
EtOAc, 8:2) of the crude residue afforded a mixture of 10α and
10β (53.0 mg, 76%). Separation by MP chromatography (toluene/
EtOAc, 7:3) gave pure 10α (35.0 mg) and 10β (16.0 mg).
3
0.67 (d, J5,6 ϭ 6.5 Hz, 3 H, 6c-H), 0.89 [s, 6 H, C(CH3)2-
CH(CH3)2], 0.93 [d, 3J ϭ 2.3 Hz, 3 H, C(CH3)2CH(CH3)(CH3)],
10α: Amorphous white solid. [α]2D0 ϭ Ϫ13.2 (c ϭ 1.0, CHCl3). H
0.94 [d, J ϭ 2.3 Hz, 3 H, C(CH3)2CH(CH3)(CH3)], 1.34 (s, 3 H,
1
3
NMR (300 MHz, CDCl3): δ ϭ 1.09 (s, 3 H, CH3CCH3), 1.12 (d, 3 CH3CCH3), 1.56 (s,
3
H, CH3CCH3), 1.67 [m,
1
H,
H, 6c-H), 1.30 (s, 3 H, CH3CCH3), 2.04, 2.10, 2.15, 2.18 (4 s, 12
C(CH3)2CH(CH3)2], 2.02, 2.08, 2.10, 2.20 (4 s, 12 H, 3 COCH3,
CH3COCH2), 2.55Ϫ2.90 [m, 4 H, (CH2)2CO], 3.39 (br. dt, 1 H, 5a-
H, 3 CH3CO, CH3COCH2), 2.50Ϫ2.89 [m, 4 H, (CH2)2CO], 3.16
3
3
3
(br. d, J3,4 ϭ 5.3 Hz, 1 H, 4b-H), 3.42Ϫ3.50 (m, 3 H, 3b-H, 5b- H), 3.58 (t, J3,4
ϭ ϭ
3J4,5 ഠ 9.4 Hz 1 H, 4a-H), 3.61 (t, J2,3
H, 6b-H), 3.67 (br. d, 3J4,5 ϭ 9.7 Hz, 1 H, 5a-H), 3.80 (dd, 2J6,6Ј
ϭ
8.0 Hz, 1 H, 2a-H), 3.79 (dd, 1 H, 2c-H), 3.87Ϫ3.91 (m, 3 H, 3a-
3
3
10.7, J6,5 ϭ 3.9 Hz, 1 H, 6Јb-H), 3.91 (dd, J2,3 ϭ 10.4 Hz, 1 H,
H, 6a-H, 6Јa-H), 3.98 (br. s, 1-H, OH), 4.09 (m, 1 H, 5b-H), 4.19
2
3
3
2c-H), 4.00 (br. d, J6,6Ј ϭ 13.2 Hz, 1 H, 6a-H), 4.07Ϫ4.16 (m, 2
(m, 2 H, 3b-H, 4b-H), 5.31 (dd, J2,3 ϭ 10.6, J3,4 ϭ 3.4 Hz, 1 H,
H, 4a-H, 6Јa-H), 4.44 (br. q, 3J5,6 ϭ 6.2 Hz, 1 H, 5c-H), 4.55Ϫ4.70
3c-H), 5.06 (br. d, 1 H, 4c-H), 5.04 (dd, J2,3 ϭ 6.3 Hz, 1 H, 2b-
3
2
(m, 6 H, 3 CHHPh, 1a-H, 1b-H, 2b-H), 4.84 (d, J ϭ 12.5 Hz, 1 H), 4.36Ϫ4.43 (m, 3 H, 6b-H, 6Јb-H, 5c-H), 4.50 (d, 1 H, CHHPh),
3
3
3
H, CHHPh), 5.04 (d, J1,2 ϭ 3.2 Hz, 1 H, 1c-H), 5.36 (br. s, 4c-H),
4.51 (d, J1,2 ϭ 7.4 Hz, 1 H, 1b-H), 4.59 (d, J1,2 ϭ 7.8 Hz, 1 H,
5.40Ϫ5.49 (m, 2 H, 2a-H, 3c-H), 5.52 (t, 3J2,3 ϭ 3J3,4 ഠ 9.5 Hz, 1 H, 1a-H), 4.61 (d, 1 H, CHHPh), 4.84 (d, 2J ϭ 12.2 Hz, 1 H, CHHPh),
3a-H), 7.11Ϫ7.99 (m, 20 H, 4 C6H5) ppm. 13C NMR (75.44 MHz,
CDCl3): δ ϭ 15.8 (6c-C), 20.7, 20.9 (3 CH3COO overlapping sig- 1c-H), 7.25Ϫ7.45 (m, 10 H, 2 C6H5) ppm. 13C NMR (100.62 MHz,
nals), 26.1, 27.3 [C(CH3)2], 27.8 (CH2COO), 29.7 (CH3COCH2), CDCl3): δ ϭ Ϫ3.0, Ϫ3.4 [Si(CH3)2], 15.3 (6c-H), 18.6, 18.7 [2 CH3
37.8 (CH3COCH2), 62.6, 65.2 (6a-C, 6b-C), 64.6, 70.0, 70.5, 71.8, of C(CH3)2CH(CH3)2], 21.0Ϫ20.3 [3 CH3COO, CH3 of
72.2, 72.7, 73.3, 74.0, 75.0, 77.0 (2a-C, 3a-C, 4a-C, 5a-C, 2b-C, 3b- C(CH3)2CH(CH3)2], 25.2 [C(CH3)2CH(CH3)2], 26.1, 27.4
C, 4b-C, 5b-C, 2c-C, 3c-C, 4c-C, 5c-C overlapping signals), 70.1, [C(CH3)2], 27.7 (CH2COO), 29.8 (CH3COCH2), 34.3
73.2, (2 CH2Ph), 96.8, 99.0, 99.4 (1a-C, 1b-C, 1c-C), 110.1 [C(CH3)2CH(CH3)2], 37.7 (CH3COCH2), 61.3 (6a-C), 63.0 (6b-C),
4.88 (d, J ϭ 10.8 Hz, 1 H, CHHPh), 5.68 (d, J1,2 ϭ 3.7 Hz, 1 H,
2
3
2
[C(CH3)2], 165.2 165.8, 169.6, 170.4, 170.8, 171.0 (3 CH3COO, 64.1 (5c-C), 69.8 (3c-C), 71.0 (5b-C), 71.4, 71.5 (2 CH2Ph), 71.8
CH2COO, 2 C6H5COO), 206.3 (CH3COCH2) ppm. MALDI-TOF (4c-C), 72.5 (2b-C), 72.9 (2c-C), 73.2 (3b-C or 4b-C), 74.3 (5a-C),
MS: m/z ϭ 1163.46 [M ϩ Naϩ], 1179.44 [M ϩ Kϩ]. C60H68O22
75.9 (3a-C), 76.7 (2a-C), 76.9 (3b-C or 4b-C), 80.5 (4a-C), 96.4 (1c-
(1141.69): calcd. C 63.15, H 6.01; found C 63.12, H 6.05.
C), 100.4 (1a-C), 100.7 (1b-C), 111.0 [C(CH3)2], 170.0, 170.6, 170.8,
Eur. J. Org. Chem. 2003, 1672Ϫ1680
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1677

A. Rencurosi, L. Poletti, G. Russo, L. Lay
FULL PAPER
171.3 (3 CH3COO, CH2COO), 206.0 (CH3COCH2) ppm. dissolved in dry CH2Cl2 (3.0 mL) and cooled to Ϫ30 °C. 0.05 
C54H78O20Si (1075.27): calcd. C 63.32, H 7.31; found C 63.45, H TMSOTf in dry CH2Cl2 (43.0 µL, 2.20 µmol) was added dropwise
7.35.
with vigorous stirring (TLC EtOAc/toluene, 1:1). After 10 min, a
new aliquot of 7 was added (50.0 mg, 0.100 mmol). After 10 min,
the mixture was neutralised with TEA and concentrated. Flash
chromatography purification (EtOAc/toluene, 2.5:8) of the crude
residue afforded 14 (116 mg, 47%) as an amorphous white solid.
[α]2D0 ϭ Ϫ9.9 (c ϭ 0.85, CHCl3). 1H NMR (400 MHz, CDCl3): δ ϭ
The regiochemistry of the glycosylation was further confirmed by
adding two drops of neat trichloroacetyl isocyanate into the NMR
tube. The recorded spectrum of the obtained derivative 11Ј showed
a downfield shift of the 3a-H proton to δ ϭ 5.25 ppm.
0.19, 0.23 [2s,
6
H, Si(CH3)2], 0.92Ϫ0.97 [m, 12 H,
Benzyl
(6-O-Acetyl-2-O-levulinoyl-β-
D
-galactopyranosyl)-(1Ǟ4)-
3
C(CH3)2CH(CH3)2], 1.07 (d, J5,6 ϭ 6.5 Hz, 3 H, 6c-H), 1.70 [m, 1
H, C(CH3)2CH(CH3)2], 1.98, 2.06, 2.13 (3 s, 9 H, 3 CH3CO), 3.33
2,3-di-O-benzoyl-6-O-thexyldimethylsilyl-β-
D-glucopyranoside (12):
Compound 5 (170 mg, 0.180 µmol), was dissolved in CH2Cl2
(8.0 mL) and cooled to Ϫ 15 °C. 60% aq. CF3COOH (1.20 mL)
was added with vigorous stirring. After 30 min at Ϫ15 °C and 2 h
at Ϫ 5 °C (TLC petroleum ether/EtOAc, 3:7), the reaction mixture
was diluted with CH2Cl2, neutralised with solid NaHCO3 and par-
titioned between water and CH2Cl2. The organic phase was dried
over Na2SO4, filtered and concentrated under reduced pressure.
Purification by flash chromatography (petroleum ether/EtOAc, 4:6)
3
3
(dd, J2,3 ϭ 9.7, J3,4 ϭ 3.2 Hz, 1 H, 3b-H), 3.38Ϫ3.44 (m, 2 H,
5b-H, 6b-H), 3.55 (br. d, 1 H, 5a-H), 3.66Ϫ3.70 (m, 2 H, 2b-H,
2
3
4b-H), 3.78 (dd, J6,6 ϭ 10.6, J6,5 ϭ 5.2 Hz, 1 H, 6a-H), 3.83 (dd,
2
1 H, 2c-H), 4.01 (br. d, 1 H, 6Јb-H), 4.14 (br. d, J6,6Ј ϭ 11.6 Hz,
1 H, 6Јa-H), 4.18 (t, J4,5 ϭ 9.5 Hz, 1 H, 4a-H), 4.33 (br. q, 1 H,
5c-H), 4.49 (d, 1 H, J1,2 ϭ 7.7 Hz, 1b-H), 4.66 (appearing as a d,
3
3
3
2 H, CHHPh), 4.67 (d, 1 H, CHHPh), 4.72 (d, J1,2 ϭ 7.9 Hz, 1
H, H-1), 4.89 (d, 2J ϭ 12.4 Hz, 1 H, CHHPh), 5.10 (d, J1,2
ϭ
3
afforded 12 (123 mg, 75%) as an amorphous white solid. [α]2D0
ϭ
3
3.7 Hz, 1 H, 1c-H), 5.27 (d, 1 H, 4c-H), 5.32 (dd, J2,3 ϭ 10.4,
3J3,4 ϭ 3.3 Hz, 1 H, 3c-H), 5.42 (t, 1 H, 2a-H), 5.61 (t, 1 H, 3J2,3 ϭ
3J3,4 ഠ 9.6 Hz, 3a-H), 7.18Ϫ8.00 (m, 20 H, 4 C6H5) ppm. 13C
NMR (100.62 MHz, CDCl3): δ ϭ Ϫ3.4, Ϫ3.0 (2 SiCH3), 15.9 (6c-
H), 18.6, 18.8 [2 CH3 of C(CH3)2CH(CH3)2], 20.3Ϫ20.8 [2 CH3 of
C(CH3)2CH(CH3)2, 3 CH3COO], 25.3 [C(CH3)2CH(CH3)2], 34.3
[C(CH3)2CH(CH3)2], 61.0 (6a-C), 62.1 (6b-C), 65.2 (5c-C), 68.6
(4b-C), 70.1 (CH2Ph), 70.1 (3c-C), 70.5 (2b-C), 71.4 (4c-C), 71.9
(2a-C), 72.2 (5b-C), 73.1 (CH2Ph), 73.4 (3a-C, 2c-C), 74.7 (4a-C),
75.6 (5a-C), 83.1 (3b-C), 99.3 (1a-C), 100.1 (1c-C), 102.3 (1b-C),
165.3, 165.7, 169.9, 170.3, 170.5 (3 CH3COO, 2 C6H5COO) ppm.
C60H76O20Si (1145.32): calcd. C 62.92, H 6.69; found C 63.05,
H 6.71.
1
Ϫ18.5 (c ϭ 1.0, CHCl3). H NMR (200 MHz, CDCl3): δ ϭ 0.25,
0.19 [2s, 6 H, Si(CH3)2], 0.93 [m, 12 H, C(CH3)2CH(CH3)2], 1.68
[m, 1 H, C(CH3)2CH(CH3)2], 2.05, 2.20 (2 s, 6 H, COCH3,
CH3COCH2), 2.53Ϫ2.85 [m, 4 H, (CH2)2CO], 3.55Ϫ3.38 (m, 4 H,
3b-H, 4b-H, 5a-H, 6a-H), 3.68Ϫ3.82 (m, 2 H, 6Јa-H, 5b-H), 4.01
(br. s, 2 H, 6b-H, 6Јb-H), 4.13 (t, 1 H, 4a-H), 4.58Ϫ4.72 (m, 3 H,
CHHPh, 1a-H, 1b-H), 4.82Ϫ4.93 (m, 2 H, CHHPh, 2b-H), 5.40 (t,
3J1,2 ϭ 7.8 Hz, 1 H, 2a-H), 5.55 (t, J2,3 ϭ 3J3,4 ഠ 9.3 Hz, 1 H, 3a-
H), 7.15Ϫ8.12 (m, 15 H, 3 C6H5) ppm. C48H62O16Si (923.08):
calcd. C 62.46, H 6.77; found C 62.33, H 6.73.
3
Benzyl (6-O-Acetyl-β-
6-O-thexyldimethylsilyl-β-
D-galactopyranosyl)-(1Ǟ4)-2,3-di-O-benzoyl-
D-glucopyranoside (13): Compound
6
(176 mg, 0.203 mmol), was dissolved in CH2Cl2 (8.0 mL) and co-
oled to Ϫ15 °C. 60% aq. CF3COOH (800 µL) was added with
vigorous stirring. After 2 h at Ϫ15 °C and 2 h at Ϫ5 °C (TLC
petroleum ether/EtOAc, 2:8) the reaction mixture was diluted with
CH2Cl2, neutralised with solid NaHCO3 and partitioned between
water and CH2Cl2. The organic phase was dried over Na2SO4, fil-
tered and concentrated under reduced pressure. Purification by
flash chromatography (petroleum ether/EtOAc, 4:6), afforded 13
(138 mg, 82%) as a white foam. [α]2D0 ϭ ϩ45.3 (c ϭ 1.0, CHCl3).
1H NMR, (300 MHz, CDCl3): δ ϭ 0.13, 0.18 [2 s, 6 H, Si(CH3)2],
Benzyl (3,4-O-Isopropylidene-β-
O-benzoyl-6-O-thexyldimethylsilyl-β-
D
-galactopyranosyl)-(1Ǟ4)-2,3-di-
D-glucopyranoside (15): Com-
pound 6 (181 mg, 0.210 mmol) was dissolved in dry MeOH (500
µL), and cooled to Ϫ20 °C under Ar. Anhydrous K2CO3 (17.0 mg,
0.123 mmol) was added and the mixture was stirred for 6 h, moni-
toring the reaction by TLC (EtOAc/toluene, 3:7). Then the solution
was cooled to Ϫ35 °C and stirred for 20 h. After diluting with
CH2Cl2, the mixture was filtered through a Celite pad, the filtrate
was concentrated and purified by flash chromatography (EtOAc/
toluene, 2:8) affording 15 (143 mg, 83%) as a white foam. [α]2D0
ϭ
0.85Ϫ0.92 [m, 12 H, C(CH3)2CH(CH3)2], 1.65 [m,
1 H,
1
ϩ39.5 (c ϭ 0.95, CHCl3). H NMR (400 MHz, CDCl3): δ ϭ 0.23,
0.20 [2 s, 6 H, Si(CH3)2]; 0.92 [s, 6 H, C(CH3)2CH(CH3)2], 0.94 [d,
C(CH3)2CH(CH3)2], 1.96 (s, 3 H, CH3CO), 3.24Ϫ3.61 (m, 8 H, 5a-
3
H, 6a-H, 2b-H, 3b-H, 5b-H, 3 OH), 3.65 (d, J4,5 ϭ 3.1 Hz, 1 H,
3J ϭ 2.6 Hz, 3 H, C(CH3)2CH(CH3)(CH3)], 0.95 [d, J ϭ 2.6 Hz,
3
4b-H), 3.70 (dd, 2J6,6Ј ϭ 11.2, 3J6,5 ϭ 5.5 Hz, 1 H, 6Јa-H), 3.95 (br.
3 H, C(CH3)2CH(CH3)(CH3)], 1.28 (s, 3 H, CH3CCH3), 1.44 (s, 3
2
d, 1 H, J6,6Ј ϭ 11.5 Hz, 6b-H), 4.15 (br. d, 1 H, 6Јb-H), 4.17 (t,
H, CH3CCH3), 1.69 [m, 1 H, C(CH3)2CH(CH3)2], 3.20 (dd, 2J6,6Ј
ϭ
ϭ
ϭ
3
3J4,5 ϭ 9.6 Hz, 1 H, 4a-H), 4.41 (d, J1,2 ϭ 7.7 Hz, 1 H, 1b-H),
3
11.8 Hz, 1 H, 6b-H), 3.34 (br. dd, 1 H, 6a-H), 3.43 (br. t, J2,3
7.4 Hz, 1 H, 2b-H), 3.52 (ddd, J4,5 ϭ 2.1, J5,6 ϭ 4.3, J5,6
6.9 Hz, 1 H, 5b-H), 3.57 (dt, 1 H, J5,6
3
4.60 (d, 1 H, CHHPh), 4.77 (d, J1,2 ϭ 7.8 Hz, 1 H, 1a-H), 4.85
3
3
3
(d, 2J ϭ 12.1 Hz, 1 H, CHHPh), 5.42 (dd, 1 H, 2a-H), 5.59 (t,
3
ϭ
3J5,6 ഠ 2.3 Hz, H-5),
3
3J2,3 ϭ J3,4 ഠ 9.5 Hz, 1 H, 3a-H), 7.18Ϫ7.97 (m, 15 H, 3 C6H5)
3
3.96Ϫ4.05 (m, 4 H, 6a-H, 6Јa-H, 3b-H, 4b-H), 4.19 (t, J4,5
ϭ
ppm. 13C NMR (50.29 MHz, CDCl3): δ ϭ Ϫ3.4, Ϫ3.1 (2 SiCH3),
18.5, 18.7, 20.3, 20.5, 20.6 [C(CH3)2CH(CH3)2, CH3COO], 25.3
[C(CH3)2CH(CH3)2], 34.3 [C(CH3)2CH(CH3)2], 61.0, 62.2 (6a-C,
6b-C), 70.2 (CH2Ph), 68.3, 71.6, 72.0, 73.4, 73.5, 73.8, 74.8, 75.6
(2a-C, 3a-C, 4a-C, 5a-C, 2b-C, 3b-C, 4b-C, 5b-C), 99.5, 102.6 (1a-
C, 1b-C), 165.2, 166.2, 170.4 (CH3COO, 2 C6H5COO) ppm.
C43H56O14Si (824.93): calcd. C 62.60, H 6.84; found C 62.52, H
6.86.
3
9.4 Hz, 1 H, 4a-H), 4.38 (d, J1,2 ϭ 8.1 Hz, 1 H, 1b-H), 4.67 (d, 1
H, CHHPh), 4.73 (d, 1 H, 1a-H), 4.89 (d, 2J ϭ 12.4 Hz, 1 H,
3
CHHPh), 5.43 (dd, J1,2 ϭ 7.8, 3J2,3 ϭ 9.7 ϭ Hz, 1 H, 2a-H), 5.61
3
(t, J3,4 ϭ 9.5 Hz, 1 H, 3a-H), 7.21Ϫ7.99 (m, 15 H, 3 C6H5) ppm.
13C NMR (100.62 MHz, CDCl3): δ ϭ 18.5, 18.6, 20.3, 20.4
[C(CH3)2CH(CH3)2], 25.5 [C(CH3)2CH(CH3)2], 27.9, 26.2
[C(CH3)2], 34.1 [C(CH3)2CH(CH3)2], 61.7, 61.8 (6a-C, 6b-C), 70.1
(CH2Ph), 71.8 (2a-C), 73.4 (4b-C), 73.7 (3a-C), 73.9 (2b-C or 5c-
Benzyl (3,4-Di-O-acetyl-2-O-benzyl-α-
O-acetyl-β- -galactopyranosyl)-(1Ǟ4)-2,3-di-O-benzoyl-6-O-thexyl- (1a-C), 101.8 (1b-C), 110.2 [C(CH3)2], 165.5, 166.1 (2 C6H5COO)
dimethylsilyl-β- -glucopyranoside (14): Compound 13 (177 mg, ppm. C44H58O13Si (823.01): calcd. C 64.21, H 7.10; found C 64.23,
0.215 mmol) and fucosyl donor 7[17] (143 mg, 0.340 mmol) were H 7.13.
L-fucopyranosyl)-(1Ǟ3)-(6- C), 74.0 (2b-C or 5c-C), 74.8 (4a-C), 75.6 (5a-C), 78.8 (3b-C), 99.2
D
D
1678
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 1672Ϫ1680

Synthesis of a Series of Fucosyllactose Building Blocks
FULL PAPER
Benzyl (3,4-Di-O-acetyl-2-O-benzyl-α-
O-isopropylidene-β-
O-thexyldimethylsilyl-β-
(138 mg, 0.168 mmol) and fucosyl donor 7[17] (113 mg, C6H5) ppm. 13C NMR, (100.62 MHz, CDCl3): δ ϭ 16.1 (6c-C),
L
-fucopyranosyl)-(1Ǟ6)-(3,4-
8.1 Hz, 1a-H), 4.88 (d, 1 H, CHHPh), 5.12 (dd, 3J2,3 ϭ 10.5, 3J3,4 ϭ
3
D
-galactopyranosyl)-(1Ǟ4)-2,3-di-O-benzoyl-6- 3.4 Hz, 1 H, 3c-H), 5.18 (d, 1 H, 4c-H), 5.43 (t, J1,2
ϭ
3J2,3
ϭ
D-glucopyranoside (16): Compound 15
8.1 Hz, 1 H, 2a-H), 5.67 (t, 1 H, 3a-H), 7.10Ϫ7.97 (m, 20 H, 4
0.234 mmol) were dissolved in dry CH2Cl2 (3.0 mL) and cooled to
Ϫ35 °C. 0.05  TMSOTf in dry CH2Cl2 (34.0 µL, 1.68 µmol) was
21.1, 21.2 (2 CH3COO), 61.9 (6a-C), 64.6 (6b-C), 64.7 (5c-C), 68.3
(4b-C), 70.5 (3c-C), 71.2 (CH2Ph), 72.0 (4c-C), 72.4 (5b-C), 72.6
added dropwise with vigorous stirring (TLC EtOAc/toluene, 4:6). (2a-C, 2b-C), 73.3 (CH2Ph), 73.8 (2c-C), 73.9 (3b-C), 74.5 (3a-C),
After 10 min, the mixture was neutralised with TEA and concen- 75.6 (5a-C), 78.2 (4a-C), 97.4 (1c-C), 100.2 (1b-C), 105.0 (1a-C),
trated. Flash chromatography purification (EtOAc/toluene, 2.5:7.5) 165.7, 165.9, 170.6, 170.9 (2 CH3COO, 2 C6H5COO) ppm.
of the crude residue afforded 16 (98.0 mg, 51%) as a white foam.
[α]2D0 ϭ Ϫ9.4 (c ϭ 1.05, CHCl3). 1H NMR (400 MHz, CDCl3): δ ϭ
0.24, 0.20 [2s, 6 H, Si(CH3)2], 0.92 [s, 6 H, C(CH3)2CH(CH3)2],
C50H56O19 (960.95): calcd. C 62.49, H 5.87; found C 62.40, H 5.93.
Benzyl (2-O-Benzyl-α-
L-fucopyranosyl)-(1Ǟ6)-(β-D-galactopyrano-
3
3
0.94 [d, J ϭ 3.3 Hz, 3 H, C(CH3)2CH(CH3)(CH3)], 0.96 [d, J ϭ
syl)-(1Ǟ4)-β- -glucopyranoside (18): Compound 17 (29.0 mg, 30.1
D
3.3 Hz, 3 H, C(CH3)2CH(CH3)(CH3)], 1.03 (d, 3J5,6 ϭ 6.5 Hz, 3 H,
µmol) was dissolved in dry methanol (1.0 mL) and cooled to 0 °C.
0.5  MeONa in dry methanol (30.0 µL, 15.0 µmol) was added
dropwise and the reaction was vigorously stirred at room tempera-
ture (TLC EtOAc/MeOH, 6:4). After 6 h a second aliquot of
MeONa solution was added (30.0 µL, 15.0 µmol). After 24 h the
reaction was neutralised with IR-120 resin (Hϩ form), filtered and
concentrated. Flash chromatography purification (EtOAc/MeOH,
8:2) afforded 18 (17.0 mg, 85%) as a glassy solid. [α]2D0 ϭ Ϫ63.7
(c ϭ 1.0, MeOH). 1H NMR (400 MHz, CDCl3): δ ϭ 1.20 (d,
6c-H), 1.27, 1.39 [2 s,
6 H, C(CH3)2], 1.69 [m, 1 H,
C(CH3)2CH(CH3)2], 1.98, 2.15 (2 s, 6 H, 2 COCH3), 2.75 (m, 2 H,
6b-H, OH), 3.19 (t, 1 H, 6Јb-H), 3.40 (t, 1 H, 2b-H), 3.53 (br. d,
3J4,5 ϭ 9.6 Hz, 1 H, 5a-H), 3.67 (ddd, 1 H, 5b-H), 3.78 (dd, 3J2,3 ϭ
3
3
11.5 Hz, 1 H, 2c-H), 3.94 (dd, J2,3 ϭ 7.4, J3,4 ϭ 5.6 Hz, 1 H, 3b-
3
3
H), 4.00 (dd, J5,6 ϭ 1.6 Hz, 1 H, 6a-H), 4.08 (dd, J5,6 ϭ 2.9,
2J6,6Ј ϭ 12.2 Hz, 1 H, 6Јa-H), 4.12Ϫ4.17 (m, 3 H, 4a-H, 4b-H, 5c-
3
3
H), 4.32 (d, J1,2 ϭ 8.2 Hz, 1 H, 1b-H), 4.52 (d, J1,2 ϭ 3.4 Hz, 1
H, 1c-H), 4.57 (d, 1 H, CHHPh), 4.65 (d, 2J ϭ 12.2 Hz, 1 H,
CHHPh), 4.67 (d, 1 H, CHHPh), 4.72 (d, J1,2 ϭ 7.9 Hz, 1 H, 1a-
H), 4.89 (d, J ϭ 12.5 Hz, 1 H, CHHPh), 5.16Ϫ5.19 (m, 2 H, 3c-
H, 4c-H), 5.42 (t, 1 H, 2a-H), 5.58 (t, 1 H, J2,3 ϭ J3,4 ഠ 9.6 Hz,
3
3J5,6 ϭ 6.6 Hz, 3 H, 6c-H), 3.31 (t, J1,2 ϭ 3J2,3 ϭ 8.4 Hz, 1 H, 2a-
3
3
3
3
H), 3.40 (ddd, J4,5 ϭ 9.4, J5,6 ϭ 4.0, J5,6Ј ϭ 2.5 Hz, 1 H, 5a-H),
2
3
3
3
3.50 (dd, J2,3 ϭ 9.7, J3,4 ϭ 4.0 Hz, 1 H, 3b-H), 3.51 (t, J2,3
ϭ
3
3
3J3,4 ϭ 8.4 Hz, 1 H, 3a-H), 3.57 (t, 3J3,4 ϭ 3J4,5 ϭ 8.4 Hz, 1 H, 4a-
3a-H), 7.19Ϫ7.98 (m, 20 H,
4
C6H5) ppm. 13C NMR,
3
3
H), 3.59 (dd, J1,2 ϭ 7.8, J2,3 ϭ 9.7 Hz, 1 H, 2b-H), 3.65Ϫ3.72
(m, 3 H, 5b-H, 6b-H, 2c-H), 3.75Ϫ3.89 (m, 4 H, 6a-H, 4b-H, 6Јb-
(100.62 MHz, CDCl3): δ ϭ Ϫ3.3, Ϫ3.0 (2 SiCH3), 15.6 (6c-C), 18.5,
18.7, 20.3, 20.4 [C(CH3)2CH(CH3)2], 20.7, 20.8 (2 CH3COO), 25.3
3
2
H, 4c-H), 3.94 (dd, J5,6 ϭ 2.5, J6,6Ј ϭ 6.6 Hz, 1 H, 6Јa-H), 3.98
[C(CH3)2CH(CH3)2],
26.1,
28.0
[C(CH3)2],
34.1
(dd, 3J2,3 ϭ 10.1, 3J3,4 ϭ 3.4 Hz, 1 H, 3c-H), 4.05 (q, 3J5,6 ϭ 6.6 Hz,
[C(CH3)2CH(CH3)2], 61.4 (6a-C), 63.9 (6b-C), 64.0 (5c-C), 69.9 (3c-
C or 4c-C), 70.1 (CH2Ph), 70.3 (5b-C), 71.6 (2a-C), 71.8 (3c-C or
4c-C), 72.5 (4a-C or 4b-C), 72.8 (CH2Ph), 73.3 (2c-C), 73.5 (3a-C),
74.0 (2b-C), 75.4, 75.5 (5a-C, 4a-C or 4b-C), 78.3 (3b-C), 96.5 (1c-
C), 99.2 (1a-C), 102.6 (1b-C), 109.5 [C(CH3)2], 165.3, 165.6, 170.0,
170.5 (2 CH3COO, 2 C6H5COO) ppm. C61H78O19Si (1143.35):
calcd. C 64.08, H 6.88; found C 64.02, H 6.85.
3
3
1 H, 5c-H), 4.37 (d, J1,2 ϭ 8.4 Hz, 1 H, 1a-H), 4.05 (d, J1,2
7.8 Hz, 1 H, 1b-H), 4.68 (d, J ϭ 11.8 Hz, 2 H, 2 CHHPh), 4.77
(d, J ϭ 11.8 Hz, 1 H, CHHPh), 4.81 (d, J1,2 ϭ 3.7 Hz, 1 H, 1c-
H), 4.92 (d, J ϭ 11.8 Hz, 1 H, CHHPh), 7.27Ϫ7.45 (m, 10 H, 2
ϭ
2
2
3
2
C6H5) ppm. 13C NMR, (100.62 MHz, CDCl3): δ ϭ 15.7 (6c-C),
61.0 (6a-C), 66.6 (5c-C), 67.4 (6b-C), 69.2 (4b-C), 69.7 (3c-C), 70.8
(CH2Ph), 71.4 (2b-C), 72.8 (2c-C), 72.9 (CH2Ph), 73.8 (4c-C), 73.9
(2a-C, 3b-C), 75.3 (3a-C), 75.5 (5a-C), 76.7 (5b-C), 79.9 (4a-C),
98.4 (1c-C); 102.1 (1b-C), 104.2 (1a-C) ppm. C32H44O15 (668.67):
calcd. C 57.47, H 6.63; found C 57.41, H 6.65.
Benzyl (3,4-Di-O-acetyl-2-O-benzyl-α-
L
-fucopyranosyl)-(1Ǟ6)-(β-
D-
galactopyranosyl)-(1Ǟ4)-2,3-di-O-benzoyl-β-
D
-glucopyranoside
(17): Compound 16 (23.0 mg, 19.8 µmol) was dissolved in dry THF
(1.0 mL) and cooled to Ϫ40 °C. 0.5  HOAc in dry THF (43.0 µL,
21.8 µmol) and 1  tetrabutylammonium bromide in dry THF
(α-L-Fucopyranosyl)-(1Ǟ6)-(β-D-galactopyranosyl)-(1Ǟ4)-α,β-D-
(23.0 µL, 21.8 µmol) were added dropwise with vigorous stirring. glucopyranose (19): Compound 18 (17.0 mg, 25.4 µmol) was dis-
The reaction was warmed to 40 °C (TLC petroleum ether/EtOAc,
1:1) and stirred for 20 h. The reaction was quenched by adding
satd. NH4Cl solution, extracted with CH2Cl2, dried over Na2SO4
and concentrated. The crude compound was dissolved in CHCl3
solved in methanol (2.0 mL), Pd/C catalyst (10.0 mg) was added
and the reaction was vigorously stirred under a hydrogen atmos-
phere at room temperature. After 3 h the reaction was filtered
through a Celite pad and concentrated, affording 19 (12.0 mg, 75%)
(2.0 mL) and cooled to 0 °C. A 70% solution of CF3COOH in as a glassy solid. [α]2D0 t ϭ 0: Ϫ25.2; t ϭ 12 h: Ϫ22.9 (c ϭ 1.0,
1
water (300 µL) was added with vigorous stirring (TLC EtOAc).
After 2 h the reaction was cooled to Ϫ5 °C, neutralised with solid
K2CO3 and partitioned between water and CHCl3. The organic
layer was dried over Na2SO4 and concentrated. Flash chromatogra-
H2O). H NMR (400 MHz, CDCl3): δ ϭ 1.44 (d, 3J5,6 ϭ 6.5 Hz, 3
3
H, 6c-H), 3.48 (t, 3J1,2 ϭ J2,3 ϭ 7.7 Hz, 0.6 H, 2a-Hβ), 3.75Ϫ3.90
(m, 4.4 H, 2a-Hα, 3a-Hβ, 5a-Hα, 2b-H, 3b-H, 4b-H), 3.96Ϫ4.16
(m, 10 H, 3a-Hα, aa-Hα, 6a-Hα, 6Јa-Hα, 4a-Hβ, 5a-Hβ, 6a-Hβ,
3
phy purification (EtOAc) of the crude residue afforded 17 (12.7 mg,
6Јa-Hβ, 4b-H, 6b-H, 6Јb-H, 2c-H, 3c-H, 4c-H), 4.29 (q, J5,6
ϭ
1
3
67%) as a white glass. [α]2D0 ϭ Ϫ16.1 (c ϭ 1.0, CHCl3). H NMR 6.5 Hz, 1 H, 5b-H), 4.67 (d, J1,2 ϭ 7.7 Hz, 1 H, 1b-H), 4.84 (d,
3
3
(400 MHz, CDCl3): δ ϭ 1.02 (d, J5,6 ϭ 6.5 Hz, 3 H, 6c-H), 1.93
3J1,2 ϭ 7.9 Hz, 0.6 H, 1a-Hβ), 5.17 (d, J1,2 ϭ 3.4 Hz, 1 H, 1c-H),
3
3
(s, 3 H, COCH3), 2.09 (s, 3 H, COCH3), 2.47 (dd, J5,6 ϭ 4.4, 5.44 (d, J1,2
ϭ
3.2 Hz, 0.4 H, 1a-Hα) ppm. 13C NMR,
3
2
2J6,6Ј ϭ 9.1 Hz, 1 H, 6b-H), 3.14 (t, J5,6 ϭ J6,6Ј ϭ 9.1 Hz, 1 H,
(100.62 MHz, CDCl3): δ ϭ 16.0 (6c-C), 60.98 (6a-Cα), 60.9 (6a-
3
3
6Јb-H), 3.26 (m, 1 H, 5b-H), 3.41 (dd, J2,3 ϭ 9.4, J3,4 ϭ 2.9 Hz, Cβ), 67.5 (5c-C), 68.2 (6b-C), 68.9, 69.3, 70.3, 70.7, 71.5, 72.0, 72.2,
1 H, 3b-H), 3.58 (t, 1 H, 2b-H), 3.67Ϫ3.62 (m, 2 H, 5a-H, 2c-H), 72.6, 73.3, 74.5, 74.7, 75.1, 75.3, 80.1, 80.2 (2a-Cα, 3a-Cα, 4a-Cα,
3.79 (br. d, 1 H, 4b-H), 3.95Ϫ4.16 (m, 4 H, 4a-H, 6a-H, 6Јa-H, 5c-
5a-Cα, 2a-Cβ, 3a-Cβ, 4a-Cβ, 5a-Cβ, 2b-C, 3b-C, 4b-C, 5b-C, 2c-
3
3
H), 4.34 (d, J1,2 ϭ 3.5 Hz, 1 H, 1c-H), 4.38 (d, J1,2 ϭ 7.5 Hz, 1 C, 3c-C, 4c-C), 92.6 (1a-Cα), 96.4 (1a-Cβ), 100.0 (1c-C), 103.9 (1b-
H, 1b-H), 4.48 (d, 2J ϭ 12.3 Hz, 1 H, CHHPh), 4.56 (d, 1 H, C) ppm. C18H31O15 (487.43): calcd. C 44.35, H 6.41; found C 44.28,
3
CHHPh), 4.64 (d, 2J ϭ 12.5 Hz, 1 H, CHHPh), 4.81 (d, J1,2
ϭ
H 6.45.
Eur. J. Org. Chem. 2003, 1672Ϫ1680
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1679

A. Rencurosi, L. Poletti, G. Russo, L. Lay
FULL PAPER
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Acknowledgments
This work was funded by EU-NOFA project (grant FAIR
CT937142), MURST and CNR (Istituto di Scienze e Tecnologie
Molecolari). The authors are grateful to Dr. Luisa Sturiale for re-
cording MALDI-TOF spectra.
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Received July 25, 2002
1680
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 1672Ϫ1680