An exceptionally simple chemical synthesis of O-glycosylated D-glucosamine derivatives by Heyns rearrangement of the corresponding O-glycosyl fructoses

Article abstract of DOI:10.1081/CAR-120023468

2-N-Acetyl-4-O-(β-D-galactopyranosyl)-D-glucosamine (N-acetyl-D-lactosamine), a very important building block of biologically relevant oligosaccharides such as sialyl Lewis^x, is easily accessible via the Heyns rearrangement of the corresponding

Full text of DOI:10.1081/CAR-120023468

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An Exceptionally Simple Chemical Synthesis of
O‐Glycosylated d‐Glucosamine Derivatives by Heyns
Rearrangement of the Corresponding O‐Glycosyl
Fructoses
Arnold E. Stütz a , Gyula Dekany a , Brigitte Eder a , Carina Illaszewicz a & Tanja M. Wrodnigg
a
a Glycogroup , Institut für Organische Chemie , Technische Universität Graz , Stremayrgasse
16, A‐8010, Graz, Austria
Published online: 16 Aug 2006.
To cite this article: Arnold E. Stütz , Gyula Dekany , Brigitte Eder , Carina Illaszewicz & Tanja M. Wrodnigg (2003) An
Exceptionally Simple Chemical Synthesis of O‐Glycosylated d‐Glucosamine Derivatives by Heyns Rearrangement of the
Corresponding O‐Glycosyl Fructoses , Journal of Carbohydrate Chemistry, 22:5, 253-265, DOI: 10.1081/CAR-120023468
To link to this article: http://dx.doi.org/10.1081/CAR-120023468
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JOURNAL OF CARBOHYDRATE CHEMISTRY
Vol. 22, No. 5, pp. 253–265, 2003
An Exceptionally Simple Chemical Synthesis of
O-Glycosylated D-Glucosamine Derivatives by
Heyns Rearrangement of the Corresponding
O-Glycosyl Fructosesy
Arnold E. Stu¨tz, Gyula Dekany, Brigitte Eder, Carina Illaszewicz,
*
and Tanja M. Wrodnigg
Glycogroup, Institut fu¨r Organische Chemie, Technische Universita¨t Graz,
Graz, Austria
ABSTRACT
2-N-Acetyl-4-O-(b-D-galactopyranosyl)-D-glucosamine (N-acetyl-D-lactosamine), a
very important building block of biologically relevant oligosaccharides such as sialyl
Lewisx, is easily accessible via the Heyns rearrangement of the corresponding O-
glycosylated ketohexose, D-lactulose. This approach can also be extended to other
glucosamine derivatives employing suitable O-glycosylated ketoses many of which
are commercially available. For example, nigerosamine (3-O-a-D-glucopyranosyl-D-
glucosamine) was prepared from turanose (3-O-a-D-glucopyranosyl-D-fructose). In
combination with a recently introduced vinylogous amide type N-protecting group,
[1,3-dimethyl-2, 4, 6 (1H, 3H, 5H)-trioxopyrimidine-5-ylidene] methyl (DTPM), this
access is clearly superior to other routes and eminently suitable for scaling up.
y
This paper is dedicated to Professor Dr. Kurt Heyns.
*
Correspondence: Tanja M. Wrodnigg, Glycogroup, Institut fu¨r Organische Chemie, Technische
Universita¨t Graz, Stremayrgasse 16, A-8010 Graz, Austria; E-mail: wrodnigg@orgc.tu-graz.ac.at.
253
DOI: 10.1081/CAR-120023468
0732-8303 (Print); 1532-2327 (Online)
www.dekker.com
Copyright D 2003 by Marcel Dekker, Inc.

254
Stu¨tz et al.
INTRODUCTION
The Heyns rearrangement, wherein ketoses react with suitable amines to form
ketosylamines which subsequently isomerise to the corresponding 2-amino-2-deoxy-
aldoses, was first discovered by Fischer[1,2] during his studies on the osazone formation
of sugars and later further investigated by Heyns and Koch in the 1950s when they
found that D-glucosamine 2 was formed in the reaction of D-fructose 1 with ammonia[3]
(Scheme 1).
Subsequently, this reaction was extended by Carson[4–6] as well as the Heyns
group[7] to a wide range of different primary and secondary amines[8] yielding the
corresponding N-substituted glucosamine derivatives. In addition, amino acids[9–12] and
other ketoses[13–16] have been employed in this reaction. Generally, despite many
efforts,[17] yields rarely exceeded 20% because this reaction suffers from a variety of
problems such as competition between hydrolysis and rearrangement of the initial
condensation product, epimer formation at position C-2 of the rearrangement product,
separation problems, Amadori rearrangement as a side reaction, disubstitution when
employing primary amines and chemical instability of some products.
Because of overestimation of these difficulties there has been practically no
synthetic application of this rearrangement. In context with a demand for multigram
quantities of N-acetyl-D-lactosamine 3, which was first discovered by Freudenberg when
he investigated blood substances,[18,19] we became interested in this reaction. Compound
3 is a constituent of various glycoproteins and glycolipids and consequently plays a very
important role in many biochemical processes.[20,21] Amongst others, it is, for example,
the key intermediate in most syntheses of LewisX[22–25] 4 and sulfo-Lex, which have
been identified as ligands of selectins, carbohydrate recognising receptors on the surface
of endothelial cells involved in cell adhesion phenomena[26–29] (Figure 1).
Not surprisingly, synthetic approaches to 3 have been investigated for many years
and it has remained an eminently interesting target for synthetic chemists. Con-
sequently, many different approaches have been reported, either by multistep chemical
syntheses,[30–35] with the inherent need for protecting groups, or by enzymatic
methods.[36–38] In addition, solid-phase approaches were reported.[23] The best
chemical syntheses, concerning yields and scale-up potential starting from lactose
and allowing access to 3 or derivatives thereof, require seven to nine steps with overall
yields ranging from 10 to, at most, 30%.[39–44] Enzymatic approaches have employed
D-galactosidases from various sources[36–38,45–51] or D-galactosyl transferases[52–55] as
components of multi-enzyme systems which require co-factor recycling. Thus far, they
have been limited to relatively small scale, and require know-how which is not
generally available in synthetically oriented laboratories.
Scheme 1. The Heyns rearrangement of D-Fructose.

Chemical Synthesis of O-Glycosylated D-Glucosamine
255
Figure 1. NAHc-Lactosamine (3) and LewisX (4).
Following the Heyns rearrangement protocol, we have recently communicated a
short and efficient synthesis of selected N-substituted D-lactosamine derivatives starting
from D-lactulose.[56] Due to limited space, this contribution could not address the
general applicability to other suitable O-glycosylketoses, nor was it possible to include
some experimental details.
Now we would like to exemplify the tremendous practicability of the Heyns
rearrangement reporting two examples of wider interest, the syntheses of new N-
protected derivatives of D-lactosamine such as 9 and D-nigerosamine 16 [3-O-(a-D-
glucopyranosyl)-D-glucosamine], starting from the corresponding commercially avail-
able glycosylated ketoses, lactulose 5 and turanose (3-O-a-D-glucopyranosyl-D-fructose)
11, respectively. The successful Heyns rearrangement of turanose is particularly
interesting due to the fact that b-elimination of the substituent at C-3 is a feasible side-
reaction potentially limiting the scope of this approach.
In the case of N-protected lactosamine, the Heyns rearrangement in combination
with the N-protecting group [1,3-dimethyl-2, 4, 6 (1H, 3H, 5H)-trioxopyrimidine-5-
ylidene]methyl (DTPM), a vinylogous amide type (23), was found to be eminently
intriguing, allowing access to the product in a straightforward procedure without
chromatography in an overall yield of 65 % starting from lactulose. This approach is,
because of the simple preparative operations and easy handling, clearly suitable for the
preparation of large amounts at low costs and in a short time.
RESULTS AND DISCUSSION
Lactulose 5 (4-O-b-D-galactopyranosyl-D-fructose), by reaction with benzylamine
following the Heyns rearrangement pathway initially gives N-benzyllactulosylamine 6,
which is converted under acidic conditions to the rearrangement product N-benzyllac-
tosamine 7. Hydrogenolysis of 7 leads to lactosamine hydrochloride 8 which chemo-
selectively undergoes N-acetylation to yield N-acetyllactosamine 3 (38 – 45%). This
reaction sequence can be performed in a one-pot procedure. Nevertheless, a final
chromatographic purification step is necessary.[56]
We have now optimized the purification of the intermediates and, by employing a
suitable N-protecting group, the corresponding lactosamine derivative precipitates from
the reaction mixture in the final step of the synthesis. Following this route, lactulose 5

256
Stu¨tz et al.
reacted with commercial grade benzylamine to give the corresponding ketosyl amine 6,
which could be obtained together with unreacted lactulose and side products by
precipitation from diethyl ether. The rearrangement was conducted in methanol in the
presence of glacial acetic acid (10:1) at room temperature within two hours. The
desired N-benzyllactosamine 7 as well as unreacted lactulose 5 and side products were
obtained as a crude solid by treatment of the reaction mixture with diethyl ether.
Hydrogenolysis of the N-benzyl group was performed in water at pH 1–2 employing
Pearlman´s catalyst (20 %) to yield a mixture of lactosamine hydrochloride 8 and
unreacted 5. Fortunately, side products from previous steps do not survive these
reaction conditions, which allows for an ‘‘indirect’’ partial purification of the mixture.
Finally, N-protection takes place in methanol employing triethylamine and 1,3-
dimethyl-5-[(dimethylamino)methylene] 2,4,6 (1H, 3H, 5H)-trioxopyrimidine (DTPM-
reagent).[57] This protecting group is stable during most reaction conditions commonly
used in carbohydrate chemistry such as acetylation, Zemple´n conditions, alkylation,
hydrogenolysis, acetal formation, silylation as well as glycosylation and can be easily
removed with ammonia, hydrazine or primary amines at room temperature in a few
minutes. Employing this protecting group, the desired lactosamine derivative 9
precipitates from the reaction mixture, whereas unreacted 5 remains in solution.
Following this method, 9 could be obtained as a white powder in an overall yield of
65% from lactulose 5. Per-O-acetylation in pyridine with acetic anhydride allowed,
Scheme 2. Synthesis of lactosamine via Heyns rearrangement.

Chemical Synthesis of O-Glycosylated D-Glucosamine
257
after recrystallisation from diisopropyl ether, access to the fully protected derivative 10
in almost quantitative yield, ready for further transformations. Interestingly, formation
of the epimer at C-2, the D-manno configured 2-amino-2-deoxysugar, was not observed
under the particular conditions employed (Scheme 2).
Likewise, turanose 11 (3-O-a-D-glucopyranosyl-D-fructose), an easily available and
cheap constituent of melezitose, a highly crystalline non-reducing trisaccharide found in
various types of honey,[58,59] could also be shown to serve as a substrate for the Heyns
rearrangement, despite the fact that the glucosyl residue at position O-3 can give rise to
a highly undesired b-elimination during the reaction. Nevertheless, it was possible to
obtain the Heyns rearrangement product, nigerosamine 14. Yields are somewhat lower
than in the case of the lactulose-to-lactosamine conversion. In this synthesis, turanose
11 was stirred with benzylamine for 3 days until TLC showed the corresponding
ketosylamine 12 as the main product. The reaction mixture was diluted with methanol
and stirred into ether to give a precipitate containing a mixture of 12, unreacted starting
material as well as side products. For the rearrangement reaction, this mixture was
Scheme 3. Synthesis of nigerosamine via Heyns rearrangement.

258
Stu¨tz et al.
dissolved in methanol/glacial acetic acid, stirred at room temperature for one to two
hours and added to an excess of diethyl ether, to give a precipitate of N-benzylni-
gerosamine 12, turanose and side products. Hydrogenolysis afforded the free amine 14
as the hydrochloride together with the starting material. Its treatment with the DTPM-
reagent gave the N-protected nigerosamine 15. Unfortunately, due to the presence of
pyranoid and furanoid tautomers at the reducing end as well as side products, this
product failed to precipitate. Consequently, per-O-acetylation followed by conventional
column chromatography was necessary to yield pure nigerosamine derivative 16
(Scheme 3).
CONCLUSION
In summary, starting from commercially available lactulose it was possible to
synthesise the DTPM-protected lactosamine derivative 9 via the Heyns rearrangement
in four steps without chromatography and in overall yields of 65%. The vinylogous
amide type protecting group employed allows for easy purification by crystallization,
leading to free sugar 9 which is ready for further transformations. Following this
approach, the corresponding nigerosamine 16 was prepared from turanose. The entire
sequence is simple and relies on cheap and commercially available reagents only. Other
glycosylated ketoses reacted accordingly,a but the observed equilibrium of furanoid and
pyranoid conformations as well as side product formation demanded purification by
column chromatography.
EXPERIMENTAL
1H NMR spectra were recorded on a Varian INOVA 500 operating at 499.925
MHz. 13C NMR spectra were recorded at 75.47 or 50.29 MHz on a BRUKER MSL
300 or on a Varian Gemini 200. Residual non-deuterated solvent was used as internal
standard. Signals of protecting groups were found in the expected regions and are not
listed explicitly. Melting points were measured on a Bu¨chi 530 apparatus and are
uncorrected. Mass spectra were recorded on an HP 1100 series MSD, Hewlett Packard.
Samples were dissolved in acetonitrile or acetonitrile/water mixtures. The scan mode
for positive ions (mass range 100–1000 D) was employed varying the fragmentation
voltage from 50 to 250 V with best molecular peaks observed at 150 V. Analytical
aMaltulose and palatinose could be converted accordingly. In case of maltulose, only the
monohydrate was commercially available. The presence of water led to lower yields, shifting the
equilibrium of the condensation reaction, the first step of the Heyns rearrangement. This was
reached at around 60% conversion of maltulose into the corresponding ketosylamine. Palatinose is
an excellent substrate for the Heyns reaction, which is driven by the ring expansion from the
furanoid fructose to the pyranoid glucosamine derivative. Both glycosylated glucosamine
derivatives were found to be mixtures of pyranoid and furanoid tautomers creating the need for
column chromatography of the N-protected derivatives which dod not precipitate well under the
conditions employed.

Chemical Synthesis of O-Glycosylated D-Glucosamine
259
TLC was performed on precoated aluminum plates silica gel 60 F254 (Merck 5554),
detected with UV light (254nm), as well as staining with 5% vanillin/sulfuric acid or
ceric ammonium molybdate (100g ammonium molybdate/4g cerium sulfate in 1L 10%
H2SO4) and heating on a hotplate. For column chromatography, silica gel 60 (230–400
mesh, Merck 9385) was employed.
GENERAL METHODS
Heyns rearrangement of glycosylated ketoses with benzylamine: Benzylamine
(7.8 equiv) was added at 0°C to the respective ketose. The reaction mixture was
allowed to reach room temperature and was subsequently stirred at 40°C until TLC
(MeOH/CHCl3/NH4OH 2:1:1) showed the ketosylamine as the main product. Methanol
(same volume as benzylamine) was added and this mixture was stirred into diethyl
ether and kept at 0°C for 3 h. The resulting precipitate consisting of the product and
unreacted starting material as well as side products was collected by filtration and dried
under reduced pressure.
The crude product was dissolved in methanol/glacial acetic acid (8:1), and stirred
at room temperature for 1–2 hours, slowly added to excess ether, and kept at 0°C for
5 h. The precipitate thus obtained containing the glycosylated N-benzylglucosamine,
unreacted starting material and side products was collected by filtration and dried under
reduced pressure.
Hydrogenolysis: The above crude material was dissolved in deionized water, the
pH value was brought to 1 by dropwise addition of concd HCL, Pearlman’s catalyst
[Pd(OH2)/C, 20%, (5 % by weight)] was added and this reaction mixture was kept on a
Parr apparatus at 3 bar until TLC (MeOH/CHCl3/NH4OH 2:1:1) showed completed
removal of the N-benzyl group. The reaction could be performed under ambient
pressure but requiring reaction times of up to 5 days.
The catalyst was filtered off, the solution was concentrated under reduced pressure
and the residue was treated with benzene/ethanol (1:1) followed by removal of the
solvent under reduced pressure. The so obtained yellowish residue contained the
glycosylated glucosamine hydrochloride and unreacted starting material.
DTPM protection: The hydrochloride of the free aminosugar was dissolved in
a small amount of methanol, triethylamine (2 equiv) and DTPM reagent (1.1 equiv
in methanol) were added and the reaction mixture was kept at room temperature
for 2 h. The solid product formed was collected by filtration and washed with me-
thanol twice.
N-Benzyllactosamine (7). Following the general procedures for the Heyns re-
arrangement, in a typical experiment lactulose 5 (50 g, 146.1 mmol) was reacted with
benzylamine (125mL, 1144.3 mmol) and stirred at 40°C for 3 days, until TLC showed
the condensation product as the main component in the mixture. Methanol (125 mL)
was added and this solution was slowly stirred into ether (5000 mL). The resulting
precipitate was collected by filtration and dried under reduced pressure. A crude pro-
duct (71.1 g) containing N-benzyllactulosylamine (6) and side products were obtained.

260
Stu¨tz et al.
This mixture was dissolved in methanol (250 mL) containing glacial acetic acid (30
mL), kept at room temperature for two h and this solution was stirred into ether (4500
mL). A precipitate containing N-benzyllactosamine 7, lactulose 5 and side products
(77.9 g in total) was obtained.
Lactosamine hydrochloride (8). The crude material (30.6 g) from the re-
arrangement reaction was dissolved in deionized water (150 mL), acidified dropwise
with concd HCl (7.6 mL) to pH 1, Pd(OH)2/C (1.5 g) was added and following the
general procedures, a mixture of 8 with lactulose 5 could be obtained (26.5 g).
N-[1,3-Dimethyl-2,4,6 (1H, 3H, 5H)-trioxopyrimidine-5-ylidene]methyl lactosa-
mine (9). The mixture obtained after hydrogenolysis (6.8 g) was dissolved in methanol
(70 mL), Et3N (3.7 mL, 26.7 mmol) and DTPM reagent (4.5 g, 21.3 mmol) in methanol
(20 mL) were added and the reaction mixture was stirred at ambient temperature for
2 h. The white, amorphous precipitate formed was collected by filtration and washed with
methanol twice to give pure 9 (4.6 g, 65% from 5). Recrystallization from CH3CN/H2O
gave an analytical sample, mp 265–267°C; [a]20 D+67.7 (c 0.68, DMSO); 13C NMR
(DMSO-d6) d 164.64, 162.56, 160.09, 152.01 (DTPM), 104.35 (C-1´), 90.41, 90.29 (C-1,
DTPM), 81.03 (C-4’), 76.08 (C-5’), 73.61 (C-3’), 71.08, 70.67, 70.14 (3 C, C-2’, C-3, C-5),
68.66 (C-4), 63.88, 60.99, 60.72 (3 C, C-2, C-6, C-6’), 27.83, 27.21 (DTPM). MS: (150V):
m/z : 508.48 [M+-H].
1
ˇ
Anal. Calcd for C19H29O13N3 . /2 H2O (516.61): C, 44.17; H, 5.86. Found: C,
43.91; H, 5.75.
1,3,6,2´,3´,4´,6´-Hepta-O-acetyl-N-[1,3-dimethyl-2,4,6 (1H, 3H, 5H)-trioxopy-
rimidine-5-ylidene]methyl lactosamine (10). To a 10% solution of 9 (10.5 g, 20.7
mmol) in pyridine, acetic anhydride (50 mL, 528.9 mmol) was added dropwise at 0°C,
a catalytic amount of dimethylaminopyridine was added and the reaction kept at room
temperature for 16 h. The solvent was removed under reduced pressure, the residue
dissolved in CH2Cl2 and the solution was consecutively washed with 6% HCl and sat
aqueous NaHCO3, then dried over MgSO4. The crude product was precipitated from
diisopropyl ether, collected by filtration and dried over P2O5 to give 15.6g (94 %) of
10. Recrystallization from CHCl3/cyclohexane gave an analytical sample, mp 145–
1
147°C; [a]20 D+64.8 (c 0.66, CHCl3); H NMR (CDCl3) d 10.16 (dd, 1H, NHDTPM),
8.06 (d, 1H, HC=CDTPM), 6.18 (d, 1 H, J1,2 3.3 Hz, H-1), 5.37 (t, 1 , J2,3= 3,4 9.8 Hz,
H-3), 5.33 (d, 1H, H-4’), 5.08 (dd, 1H, H-2’), 4.93 (m, 1 H, J2’,3’ 10.3 Hz, J3’,4’ 3.0 Hz,
H-3’), 4.46 (d, 1 H, J1’,2’ 7,9 Hz, H-1’), 4.39 (m, 1 H, J6a,6b 12.1 Hz, H-6a), 4.14 – 4.04
(m, 3H, H-6b, H-6’a, H-6’b), 3.97 (m, 1H, H-5), 3.87 – 3.79 (m, 2H, H-2, H-4), 3.66 –
3.61 (ddd, 1 H, J5’,6’a= 4’,5’ 9.7 Hz, J5’,6’b 3.5 Hz, H-5’), 3.2 (2s, 6H, 2 NCH3); 13C NMR
(CDCl3) d 170.09, 169.98, 169.89, 169.84, 169.38, 168.86, 168.53 (acetyl), 164.45,
162.41, 158.41, 151.68 (DTPM), 100.86 (C-1´), 92.41 (DTPM), 89.82 (C-1), 74.86 (C-
4), 70.68, 70.60, 70.52 (3 C, C-2, C-5, C-3’), 70.09 (C-3), 68.89 (C-2’), 66.40 (C-4’),
61.36, 61.26, 60.63 (3 C, C-5’, C-6, C-6’), 27.67, 27.05 (DTPM), 20.63, 20.60, 20.51,
20.46, 20.29 (acetyl). MS (150V): m/z : 802.7 [M+-H];
Anal. Calcd for C33H43O20N3 (801.8): C, 49.44; H, 5.41. Found: C, 49.27; H, 5.48.
N-Benzylnigerosamine (13). Following the general procedure for the Heyns
rearrangement in a typical experiment, turanose 11 (3 g, 8.8 mmol) was reacted with

Chemical Synthesis of O-Glycosylated D-Glucosamine
261
benzylamine (7.5 mL, 68.7 mmol) and the mixture stirred at 40°C for 4 days, when
TLC showed the condensation product as the main component in the mixture. Methanol
(7.5 mL) was added and this solution then stirred into ether (400 mL). The precipitate
was collected by filtration and dried. A slightly yellow material (3.0 g) containing N-
benzylturanosyl amine 12 and side products was obtained. This crude material (2.9 g)
was dissolved in MeOH/HOAc (14/2 mL), kept at room temperature for 90 min and
this solution was stirred into 900 mL of ether. A solid (2.7 g) containing N-benzyl-
nigerosamine 13, turanose 11 and side products was collected.
Nigerosamine hydrochloride (14). The rearrangement mixture (4.14 g) were
dissolved in 50 mL deionised water, acidified dropwise with concd HCl (0.5 mL), 10%
by weight of Pd(OH)2/C (20 wt.%) was added and, following the general procedures,
3.84 g of a mixture of 14 and turanose 11 were obtained.
1,4,6,2´,3´,4´,6´-Hepta-O-acetyl-N-(1,3-dimethyl-2,4,6 (1H, 3H, 5H)-trioxopy-
rimidine-5-ylidene)methyl nigerosamine (16). The above mixture (3.27 g) was
dissolved in methanol (30 mL). Et3N (1.8 mL, 13 mmol) and DTPM reagent (2.7 g,
12.8 mmol) in methanol (5 mL) were added and the reaction mixture was stirred at
room temperature for 2 h. For purification and identification, the compounds were per-
O-acetylated. The residue (7.81 g) was dissolved in pyridine (30 mL, 371 mmol), acetic
anhydride (15 mL, 158.5 mmol), and a catalytic ammount of DMDP was added, and
the reaction was stirred at room temperature for 3 h. Methanol was added, the volume
was reduced to 50% under reduced pressure and the resulting solution was diluted with
CH2Cl2, washed with 6% aqueous HCl, satd NaHCO3, dried over Na2SO4 and
concentrated under reduced pressure. Column chromatography employing ethyl acetate/
cyclohexane 3:1 gave a mixture of furanoid and pyranoid tautomers of per-O-Ac-
NHDTPM nigerosamine (16) in an overall yield of 15% from turanose. Recrystalliza-
tion from CHCl3/cyclohexane gave an analytical sample of 16 (pyranose form), [a]20
1
D+126.9 (c 0.63, CHCl3); H NMR (CDCl3) d 10.18 (m, 1H, NHDTPM), 8.27 (d, 1 H,
J 13.68 Hz, HC=CDTPM), 6.25 (d, 1 H, J1,2 3.4 Hz, H-1), 5.36 (d, 1 H, J1’,2’ 3.9 Hz,
H-1’), 5.26 (m, 1H, H-3’), 5.20 (m, 1H, H-3), 4.98 (m, 1 H, J3’,4’ 9.8 Hz, H-4’), 4.80
(dd, 1 H, H-2’), 4.26 (m, 1 H, J
10.3 Hz, J4,5 9.3 Hz, H-4), 4.19 (dd, 1 H, J5,6a 4 Hz,
3,4
J6a,6b 12.2 Hz, H-6a), 4.06 (dd, 1 H, J5’,6’a 2.4 Hz, J6’a,6’b 12.7 Hz, H-6’a), 4.01 – 3.29
(m, 3H, H-6b, H-5, H-6’b), 3.83 (ddd, 1 H, J2,3 10.3 Hz, H-2), 3.61 (ddd, 1H, H-5’); 13C
NMR (CDCl3) d 170.90, 170.78, 170.69, 169.75, 169.53, 169.40, 168.66 (acetyl),
165.37, 162.11, 159.74, 152.04 (DTPM), 95.73 (C-1´), 93.01 (DTPM), 90.67 (C-1),
72.94 (C-4), 70.41 (C-5), 70.27, 70.17 (2 C, C-2’, C-3’), 69.22 (C-3), 68.21 (C-5’),
67.81 (C-4’), 62.57 (C-2), 61.40 (C-6), 61.15 (C-6’), 28.18, 27.47 (DTPM), 20.99,
20.92, 20.80, 20.76, 20.45 (acetyl). MS (150V): m/z : 802.7 [M+-H].
Anal. Calcd for C33H43O20N3 (801.8): C, 49.44; H, 5.41. Found: C, 49.30; H, 5.47.
ACKNOWLEDGMENTS
Glycogroup appreciate financial support by the Austrian Fonds zur Fo¨rderung der
Wissenschaftlichen Forschung (FWF), Vienna (Projects P-13593 CHE and 15726-N03)
as well as Hertha-Firnberg-Fellowship T-18 CHE and Erwin Schro¨dinger-Stipend
J2092 to T. M. W. Dr. Gu¨nther Gradnig (Fresenius Austria, Linz) is acknowledged for

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a generous gift of lactulose. G. D. thanks TU Graz for a guest professorship (March–
July 2001).
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Received October 11, 2002
Accepted March 21, 2003