Synthesis of 4-O-glycosylated 1,5-anhydro-d-fructose and of 1,5-anhydro-d-tagatose from a common intermediate 2,3-O-isopropylidene-d-fructose

Article abstract of DOI:10.1016/j.carres.2009.03.005

Four novel disaccharides of glycosylated 1,5-anhydro-d-ketoses have been prepared: 1,5-anhydro-4-O-β-d-glucopyranosyl-d-fructose, 1,5-anhydro-4-O-β-d-galactopyranosyl-d-fructose, 1,5-anhydro-4-O-β-d-glucopyranosyl-d-tagatose, and 1,5-anhydro-4-O-β-d-galac

Full text of DOI:10.1016/j.carres.2009.03.005

Carbohydrate Research 344 (2009) 1014–1019
Contents lists available at ScienceDirect
Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Note
Synthesis of 4-O-glycosylated 1,5-anhydro-D-fructose and
of 1,5-anhydro-D-tagatose from a common intermediate
2,3-O-isopropylidene-D-fructose
a
b
Károly Agoston a, , Gyula Dékány , Inge Lundt
*
a Glycom A/S, Technical University of Denmark, Building 201, DK-2800 Kgs. Lyngby, Denmark
b Department of Chemistry, Technical University of Denmark, Building 201, DK-2800 Kgs. Lyngby, Denmark
a r t i c l e i n f o
a b s t r a c t
Article history:
Four novel disaccharides of glycosylated 1,5-anhydro-
D
-ketoses have been prepared: 1,5-anhydro-4-
-galactopyranosyl- -fructose, 1,5-anhydro-4-
-tagatose, and 1,5-anhydro-4-O-b- -galactopyranosyl- -tagatose. The common
-fructopyranose, was prepared from -fructose and
-tagatose derivative by oxidation followed by stereoselective reduction to the 4-
Received 28 January 2009
Received in revised form 4 March 2009
Accepted 5 March 2009
O-b-
O-b-
D
-glucopyranosyl-
-glucopyranosyl-
D
-fructose, 1,5-anhydro-4-O-b-
D
D
D
D
D
D
intermediate, 1,5-anhydro-2,3-O-isopropylidene-b-
was converted into the
D
D
Available online 12 March 2009
D
epimer. The anhydroketoses thus prepared were glycosylated and deprotected to give the disaccharides.
Keywords:
1,5-Anhydro-
1,5-Anhydro-
Ó 2009 Elsevier Ltd. All rights reserved.
D
-fructose
-tagatose
D
Glycosylated 1,5-anhydro-
Glycosylated 1,5-anhydro-
Chemical synthesis
D
-fructose
-tagatose
D
The naturally occurring monosaccharide 1,5-anhydro-
D
-fruc-
and antibacterial activities.12 For these purposes a synthetic alter-
native to the enzymatic procedure mentioned above for the prep-
aration of AF has been published recently.2 This is based on the
tose (AF, Fig. 1) has attracted much attention due to its inter-
esting biological and chemical properties.1 For the vast
amounts of investigations resulting in patents on its properties
and potential use in both food and non-food applications, as
simplest reaction, namely
(Zemplén) of tetra-O-acetyl-2-hydroxy-
2,3,4,6-tetra-O-acetyl- -arabino-hex-1-enitol), the acetylated enol
a
successful basic deacetylation
D
-glucal (1,5-anhydro-
summarized in our patent,2 1,5-anhydro-
D
-fructose has been
D
prepared mainly by enzymatic degradation of starch using an
a
ether of AF,2 a reaction which previously had been met with many
drawbacks.1 Lichtenthaler and his group also have now prepared
AF13 in a very similar fashion successfully.2 The paper13 contains
descriptions of the preparation of (ꢀ)-bissetone and (ꢀ)-palyth-
azine, which have already appeared as notes during the 1980s, as
previously reviewed.1
-glucan lyase.1,3
One of the more interesting properties of AF might be its anti-
oxidant activity,4 and consequently its ability to prevent enzy-
matic browning and pigment discoloration, which is of interest
in the food industry.5 Compared to the commonly used antioxi-
dant, ascorbic acid, AF prevents the oxidation of linoleic acid even
more effectively.6 In contrast to ascorbic acid, AF has great stabil-
ity in aqueous solutions since it is not oxidized by molecular oxy-
gen.7 Due to its non-toxic character8 the biological properties of
AF in pharmaceutical and healthcare areas are an ongoing
research topic.2,9
In addition to its chemical synthesis, the enzymatic synthesis of
AF has been improved significantly.14
AF has been detected exclusively as a monomeric compound in
natural sources,1 but recently novel oligosaccharides having AF at
OH
O
OH
O
The use of carbohydrates as chiral building blocks for synthesiz-
ing more complex asymmetric structures in enantiomerically pure
form10 has also been considered for AF, and previous examples
have been summarized.1 Recent examples are the conversion of
AF into deoxymannojirimycin (DMJ), an important mannosidase
inhibitor,11 and into ascopyrone P, a compound with antioxidant
OH
OH
OH
OH
OH
keto form
1,5-Anhydro-D-fructose; AF
O
OH
hydrate form
* Corresponding author. Tel.: +45 45252259; fax: +45 45933968.
E-mail address: ka@glycom.dk (K. Agoston).
Figure 1. Structure of 1,5-anhydro-D-fructose.
0008-6215/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2009.03.005

K. Agoston et al. / Carbohydrate Research 344 (2009) 1014–1019
1015
the reducing end have been synthesized by enzymatic methods.
Thus, glucosyl 1?3 1,5-anhydrofructose (1,5-anhydro-3-O-
glucopyranosyl- -fructose) has been prepared enzymatically
O
O
O
O
O
O
O
O
O
a-D-
b
OH
a
D
from AF and b-cyclodextrin employing cyclodextrin glucanotrans-
ferase and glucoamylase.15 Likewise, a series of oligosaccharides
have been prepared by glycosylation of the 6-position of AF
with dextran oligomers using dextransucrase for enzymatic
transglycosylation.16
O
OH
O
O
O
2
3
1
c
OH
O
OH
O
Following our successful deacetylation of the fully acetylated 2-
OH
O
hydroxy-D-glucal to 1,5-anhydro-D
-fructose (AF),2 it was obvious to
HO
HO
O
investigate similar deacetylation reactions of other 2-acyloxy-gly-
cals. In the light of the interest in disaccharide analogues of AF,
O
HO
O
HO
O
investigation of deacetylation of hepta-O-acetyl-2-hydroxy-
tal (1,5-anhydro-4-O-(b- -galactopyranosyl)- -arabino-hex-1-eni-
tol) was undertaken. The reaction did not meet with much
success since several compounds were formed, among which
D-lac-
O
D
D
4
4a
4b
Scheme 1. Reagents and conditions: (a) Dess–Martin periodinane, CH2Cl2, ambient
temperature, 3 h (80%); (b) NaBH4, MeOH, ambient temperature, 30 min (89%); (c)
80% AcOH, 65 °C, 30 min (95%).
D
-
galactose was isolated. This might indicate a b-elimination of this
sugar. Thus, this approach was not investigated further.
Introducing glycosyl moieties onto AF at specific positions by
chemical synthesis requires partly protected AF derivatives. For
this purpose our recently reported method for preparation AF from
After some preliminary experiments the use of imidate leaving
groups on the glycosyl donors was selected since a glycosylation
reaction with thioalkyl leaving groups afforded the formation of
corresponding orthoesters using NIS/AgOTf activation. Efforts to
rearrange the orthoesters formed in situ with more acid resulted
in low yields due to decomposition. Using trichloroacetimidate
leaving groups, there was no sign of orthoester formation.
D
-fructose is suitable.17 The method involves five steps giving ni-
cely crystalline intermediates and yielding AF in yields of around
35% using a tosylated intermediate. By using a mesylated interme-
diate, AF can be isolated in a 65% yield based on
chemical route has the advantage of giving access to the 1,5-anhy-
dro-2,3-O-isopropylidene- -fructose (1), the last intermediate be-
D
-fructose.17 This
Four glycosyl 1,5-anhydro-ketoses were prepared using tetra-O-
D
acetyl-
a-D
-glucopyranosyl trichloroimidate (5)20 and tetra-O-acet-
fore the final deprotection to AF. Compound 1 has one free OH-
group, which is the OH-4 in AF. Thus, unlike the direct access to
AF by the deacetylation method discussed above, this method is
unique for derivatization of AF at the 4-position, including conver-
yl-a
-D
-galactopyranosyl trichloroimidate (6)21 as donors and the
two protected 1,5-anhydro-ketoses 1 and 3 as acceptors. The gly-
cosylations were performed in dichloromethane in the presence of
molecular sieves. The donors were activated with BF3ꢁEt2O, and the
reaction temperature was varied from ꢀ50 to ꢀ20 °C to give the fully
protectedb-linkeddisaccharides7, 8, 9, and10inhighanomericpur-
ity. Deacetylation using sodium methoxide in methanol gave the
disaccharides 11, 12, 13, and 14. Acidic hydrolysis to remove the iso-
propylidene groups gave the free disaccharides 15, 16, 17, and 18,
respectively. The disaccharides were then dissolved in water and
lyophilized to afford solid materials. Structures of the products were
proven by 1D and 2D NMR spectroscopy, MS, and elemental analy-
ses. Elemental analyses data suggest that the fructose-containing
disaccharides in our case were isolated as their monohydrates.
sion to the C-4 epimeric 1,5-anhydro-
In this paper we describe the use of 1,5-anhydro-2,3-O-isopro-
pylidene-b- -fructopyranose (1) for glycosylation to give 4-O-gly-
cosylated AF disaccharides. Furthermore, was successfully
converted to the 4-epimer by oxidation and stereoselective reduc-
tion to give the 1,5-anhydro-2,3-O-isopropylidene-b- -tagatopyra-
nose (3). Similar glycosylations and deprotection gave 4-O-
glycosylated 1,5-anhydro- -tagatose derivatives. Thus, four new
D-tagatose derivative.
D
1
D
D
4-O-glycosylated 1,5-anhydro-ketoses have been prepared.
The antioxidant properties of the previously prepared oligosac-
charides15,16 have been claimed to be similar to those of AF, while
glucosylated AF derivatives have also been claimed as anti-inflam-
matory drugs and health foods18 as well as an immunosuppressant
and anti-allergy agents.19
It is known that 1,5-anhydro-D-fructose exists as the hydrated
form in aqueous solution, but the hydration process is slow.1
Recording an NMR spectrum immediately after dissolving AF in
D2O gives a complicated spectrum showing monomeric as well
as dimeric structures,1 while after 5 h only the hydrated form is
Thus, the 2,3-O-isopropylidene derivative of AF 117 was
oxidized with Dess–Martin periodinane in dichloromethane to give
the 4-keto derivative 2 (Scheme 1). Experiments using Swern type
oxidation methods (DMSO/oxalyl chloride, DMSO/Ac2O) afforded
significantly lower yields due to the formation of the methylthio-
methyl ether side product. Acidic cleavage of the isopropylidene
function of compound 2 gave the deprotected derivative 4. Inter-
pretation of the NMR data suggested that during the reaction
and/or work-up subsequent opening of the cyclic hemiketal
function occurred to give the diketo derivative 4a, which is in equi-
librium with the more stable conjugated derivative 4b (Scheme 1).
This confirmed further the structure of 2.
present. 1,5-Anhydro-D-tagatose also forms a hydrate in water
slowly, while this monosaccharide shows no tendency to form
dimeric structures.22 The NMR spectra presented in Section 1 were
measured after complete hydration.
In conclusion, four novel disaccharides were prepared by
glycosylating 1,5-anhydro-ketoses. The disaccharides thus pre-
pared probably have antioxidant properties similar to those of
AF;15,16 furthermore, they will be suitable for conjugation to
proteins via their keto function as indicated in the literature.15
1. Experimental
Sodium borohydride reduction of the keto function in 2 resulted
in formation of the epimeric 1,5-anhydro-D-tagatose derivative 3 in
high stereoselectivity and yield. Only traces of the fructo epimer 1
could be detected by TLC of the crude material.
1.1. General methods
Commercially available starting materials were used without
further purification. Solvents were dried according to standard
methods. Compound 1 was prepared according to literature proce-
Glucosylation and galactosylation were performed using the
1,5-anhydrofructose 1 and 1,5-anhydrotagatose 3 derivatives as
glycosyl acceptors (Scheme 2). The acid stability of the isopropyli-
dene groups on the acceptor turned out to be high enough to resist
acid-catalyzed glycosylation conditions.
dures.17 NMR spectra were recorded on
a
Bruker AMX-400
(100.62 MHz for 13C) or DRX-500 (125.83 MHz for 13C) spectrometer

1016
K. Agoston et al. / Carbohydrate Research 344 (2009) 1014–1019
R2
OAc
O
O
O
O
O
O
O
R1
AcO
a
R4
R3
R6
R5
+
OAc
O
NH
O
O
R5
R6
H
Cl3C
R1 R2
OAc H
R3 R4
7
8
9
β-D-GlcOAc
H
β-D-GalOAc
H
1
3
OH
H
H
OH
β-D-GlcOAc
H
β- -GalOAc
D
5
6
b
H
OAc
10
O
O
OH
R8
O
R8
R7
c
O
OH
OH
O
R7
R7
β-D-Glc
H
OH
R8
H
β-D-Glc
H
R7
R8
H
β-D-Glc
H
11
12
β-D-Glc
15
16
H
13 β-D-Gal
17 β-D-Gal
14
H
β- -Gal
D
18
H
β- -Gal
D
OAc
AcO
AcO
OAc
OH
HO
HO
OH
O
AcO
AcO
O
O
O
O
HO
HO
O
O
O
OAc
β−D-GlcOAc
OAc
β-D-GalOAc
OH
β-D-Glc
OH
β−D-Gal
Scheme 2. Reagents and conditions: (a) BF3ꢁEtO2, CH2Cl2, 4 Å, ꢀ50 to ꢀ20 °C, 1 h; (b) NaOMe, MeOH, ambient temperature, 30 min; (c) 80% AcOH, 65 °C, 30 min.
using DMSO-d6 as the solvent. All chemical shifts are quoted in ppm
downfield using solvent peaks as references (DMSO-d6: 1H:
2.50 ppm, 13C: 39.4 ppm). Kieselgel 60 (E. Merck, Darmstadt,
Germany) was used for column chromatography. MALDI-TOFMS
measurementswerecarriedoutonaBrukerBiflexIII massspectrom-
eter. 2,5-Dihydroxybenzoicacidwasusedasmatrix, and100–200la-
ser shots were applied for each spectrum. Optical rotations were
measured on a Perkin–Elmer 241 polarimeter, and the concentra-
76.4 (C-5), 70.8 (C-1), 68.4 (C-6), 28.3 and 26.3 (2 ꢃ –CH3). Anal.
Calcd for C9H12O5: C, 54.00; H, 6.04. Found: C, 54.11; H, 6.12.
1.3. 1,5-Anhydro-2,3-O-isopropylidene-b-D-tagatopyranose (3)
To a solution of 2 (200 mg, 1.00 mmol) in MeOH (10 mL) NaBH4
(75.6 mg, 2.00 mmol) was added at ambient temperature. The mix-
ture was stirred for 30 min, and was then diluted with EtOAc
(200 mL), and the organic phase was washed with water
(3 ꢃ 50 mL). The combined washings were extracted with EtOAc
(3 ꢃ 50 mL), and the combined organic phases were dried
(Na2SO4), filtered, and concentrated to a residue. Column chroma-
tography (6:4 hexane–EtOAc) gave 1,5-anhydro-2,3-O-isopropyli-
tions are given in units of g 100 mLꢀ1. ½a D25
ꢂ
values are given in units
of 10ꢀ1 deg cm2 gꢀ1
.
1.2. 1,5-Anhydro-2,3-O-isopropylidene-
D-threo-hex-4-
ulopyran-2-ose (2)
dene-b-
½ ꢂ
D-tagatopyranose (3) (180 mg, 89%) as a colorless syrup:
Dess–Martin periodinane (2.62 g, 6.18 mmol) was added to a
solution of 1,5-anhydro-2,3-O-isopropylidene-b- -fructopyranose
a 2D5
+44.2 (c 0.16, acetone); 1H NMR (DMSO-d6): d 5.14 (d, 1H,
D
J4,OH 5.34 Hz, 4-OH), 4.24 (m, 1H, H-4), 4.20 and 3.97 (2dd, each
1H, Jgem 9.92 Hz, J5,6 1.78 and ꢄ1 Hz, H-6, H-60), 4.13 and 3.72
(2d, each 1H, Jgem 8.40 Hz, H-1, H-10), 4.02 (d, 1H, J3,4 8.14 Hz, H-
3), 3.80 (m, 1H, H-5), 1.49 and 1.37 (2s, each 3H, CH3); 13C NMR
(DMSO-d6): d 114.8 (–C(CH3)2), 98.9 (C-2), 77.8 (C-3), 69.6 (C-5),
69.6 (C-1), 65.0 (C-4), 64.0 (C-6), 28.1 and 26.0 (2 ꢃ –CH3). Anal.
Calcd for C9H14O5: C, 53.46; H, 6.98. Found: C, 53.07; H, 7.02.
For comparison, spectra were also measured in MeOH-d4, and
they showed 3 to be different from 2.17
(1,17 1.00 g, 4.95 mmol) in dry CH2Cl2 (40 mL), and the reaction mix-
ture was stirred for 3 h at ambient temperature. The reaction was
monitored by TLC (1:1 hexane–EtOAc), and after completion the
mixture was diluted with EtOAc (200 mL) and was washed with aq
NaHCO3 (3 ꢃ 50 mL). The organic phase was dried (Na2SO4), filtered,
and concentrated to a syrup, which was purified by column chroma-
tography (6:4 hexane–acetone) to give the title compound 2
(800 mg, 80%) as a colorless solid: mp 83–87 °C; ½a D25
ꢂ
+37.8 (c 0.19,
MeOH); 1H NMR (DMSO-d6): d 4.83 (s, 1H, H-3), 4.55 and 4.13 (2d,
each 1H, Jgem 9.14 Hz, H-1, H-10), 4.39 and 4.16 (2m, each 1H, H-6,
H-60), 4.15 (m, 1H, H-5), 1.63 and 1.48 (2s, each 3H, CH3); 13C NMR
(DMSO-d6): d 204.3 (C-4), 117.4 (C(CH3)2), 103.0 (C-2), 86.8 (C-3),
1H NMR (MeOH-d4): d 4.38 (m, 1H, H-4), 4.36 and 3.87 (2 ꢃ d,
each 1H, Jgem 10.21 Hz, H-6), 4.25 and 3.78 (2 ꢃ dd, each 1H, Jgem
8.85 Hz, H-1), 3.87 (m, 1H, H-3), 3.79 (m, 1H, H-5), 1.58 and 1.42
(2s, each 3H, CH3); 13C NMR (MeOH-d4): d 116.9 (–C(CH3)2),

K. Agoston et al. / Carbohydrate Research 344 (2009) 1014–1019
1017
100.4 (C-2), 78.9 (C-3), 71.3 and 70.9 (C-1 and C-5), 66.5 (C-4), 65.3
1H NMR (DMSO-d6): d 5.24 (dd, 1H, J2 ,3 9.78 Hz, J3 ,4 9.78 Hz, H-
0
0
0
0
0
0
0
0
(C-6), 28.0 and 26.0 (2 ꢃ –CH3).
30), 4.92 (dd, 1H, J4 ,5 9.78 Hz, H-40), 4.86 (d, 1H, J1 ,2 7.88 Hz, H-
10), 4.77 (dd, 1H, H-20), 4.53 (d, 1H, J3,4 6.31 Hz, H-3), 4.47 (dd,
1H, J4,5 1.57 Hz, H-4), 4.18 and 4.04 (2dd, each 1H, Jgem 12.30 Hz,
H-60), 4.09 (m, 2H, H-1), 4.05 (m, 1H, H-5), 3.99 (m, 1H, H-50),
3.92 and 3.64 (2dd, each 1H, Jgem 11.35 Hz, J5,6 3.47 Hz and
8.20 Hz, H-6), 2.02, 2.00, 1.98 and 1.94 (4s, each 3H, 4 ꢃ OAc),
1.4. (R)-4,5-dihydroxy-6-(hydroxymethyl)-2H-pyran-3(6H)-one (4b)
A mixture of 2 (1.00 g, 4.95 mmol) and 80% aq AcOH (10 mL)
was stirred for 30 min at 65 °C, and was then concentrated and
co-concentrated with toluene. The residue was then dissolved in
water (10 mL) and lyophilized to afford 4b (850 mg, 95%) as a col-
orless glass: 1H NMR (D2O): d 4.35 (m, 3H, H-1 and H-5), 3.92 and
3.78 (2dd, each 1H, Jgem 12.61 Hz, J5,6 2.52 and 5.36 Hz, H-6, H-60);
13C NMR (D2O): d 178.1 (C-4), 173.9 (C-2), 130.0 (C-3), 79.0 (C-5),
66.6 (C-1), 61.0 (C-6).
13
1.29 (s, 6H, 2 ꢃ –CH3); C NMR (DMSO-d6): d 99.8 (C-10), 75.5
(C-4), 75.3 (C-3), 74.6 (C-5), 72.3 (C-1), 71.7 (C-30), 70.4 (C-20),
70.1 (C-50), 68.7 (C-6), 68.0 (C-40), 61.2 (C-60), 26.4 and 25.4
(2 ꢃ –CH3), 20.2 (4 ꢃ OAc); MALDI-TOFMS: Calcd for C23H32O14
:
532. Found: 555 [M+Na]+, 571 [M+K]+.
1.8. 1,5-Anhydro-2,3-O-isopropylidene-4-O-b-(2,3,4,6-tetra-O-
1.5. General procedures
acetyl-D-galactopyranosyl)-D-fructopyranose (9)
1.5.1. Glycosylation
Coupling of donor 6 with acceptor 1 according to the general
A solution of glycosyl acceptor (300 mg, 1.48 mmol) and glyco-
syl donor (875 mg, 1.77 mmol) in dry CH2Cl2 (5 mL), containing 4 Å
molecular sieves (500 mg) was cooled to ꢀ50 °C. Then, a solution
procedure resulted in 9 (65%) as a syrup: ½a D25
ꢀ23.1 (c 0.6,
0 0 0
ꢂ
CHCl3); 1H NMR (DMSO-d6): d 5.27 (dd, 1H, J3 ,4 3.57 Hz, J4 ,5
0
<1 Hz, H-40), 5.14 (dd, 1H, J2 ,3 10.18 Hz, H-30), 4.96 (dd, 1H,
0
0
J1 ,2 7.89 Hz, H-20), 4.90 (d, 1H, H-10), 4.19 (m, 1H, H-4), 4.16
(m, 1H, H-50), 4.13 and 3.87 (2d, each 1H, Jgem 8.83 Hz, H-1),
4.09 and 3.99 (2m, each 1H, H-6), 4.06 (d, 1H, H-3), 4.05 (m,
2H, H-60), 3.95 (m, 1H, H-5), 2.12, 2.01, 1.99 and 1.92 (4s, each
3H, 4 ꢃ OAc), 1.46 and 1.35 (2s, each 3H, 2 ꢃ –CH3); 13C NMR
(DMSO-d6): d 98.4 (C-10), 84.0 (C-3), 80.3 (C-4), 70.1 (C-5), 69.7
(C-50), 70.0 (C-30), 69.6 (C-1), 68.5 (C-20), 66.8 (C-40), 65.8 (C-6),
60.7 (C-60), 27.9 and 24.9 (2 ꢃ –CH3), 20.3, 20.3, 20.2 and 20.2
0
0
of BF3ꢁEt2O (100
lL) in CH2Cl2 (1 mL) was added, and the reaction
mixture was stirred for 1 h at ꢀ20 °C. After addition of pyridine
(200 L) and EtOAc (100 mL), the mixture was filtered, and the fil-
l
trate was washed with aq NaHCO3 (3 ꢃ 50 mL). The organic phase
was dried (Na2SO4), filtered, and concentrated to a residue that was
purified by column chromatography (95:5 CH2Cl2–acetone) to give
the disaccharide.
1.5.2. Deacetylation
(4 ꢃ OAc); MALDI-TOFMS: Calcd for C23H32O14
: 532. Found:
To
a
solution of fully protected disaccharide (400 mg,
555 [M+Na]+, 571 [M+K]+.
0.75 mmol) in dry MeOH (5 mL) was added NaOMe (50 mg), and
the mixture was stirred for 30 min at ambient temperature. The
solution was neutralized with Amberlite IR 120 (H+) resin, filtered,
and concentrated. Column chromatography (8:2 CH2Cl2–MeOH) of
the residue gave the products.
1.9. 1,5-Anhydro-2,3-O-isopropylidene-4-O-b-(2,3,4,6-tetra-O-
acetyl- -galactopyranosyl)- -tagatopyranose (10)
D
D
Coupling of donor 6 with acceptor 3 according to the general
procedure resulted in 10 (73%) as a syrup: ½a D25
ꢂ
ꢀ10.4 (c 0.9,
CHCl3); 1H NMR (DMSO-d6): d 5.26 (dd, 1H, J3 ,4 3.47 Hz, J4 ,5
0
0
0
0
1.5.3. Acid hydrolysis
<1 Hz, H-40), 5.14 (dd, 1H, J2 ,3 10.40 Hz, H-30), 4.94 (dd, 1H, J1 ,2
0
0
0
0
A mixture of starting compound (100 mg, 0.27 mmol) and 80%
aq AcOH (10 mL) was stirred for 30 min at 65 °C, and was then con-
centrated and co-concentrated with toluene. Finally, the residue
was dissolved in water (3 mL) and lyophilized to afford the
products.
7.88 Hz, H-20), 4.78 (d, 1H, H-10), 4.53 (d, 1H, J3,4 6.30 Hz, H-3),
4.47 (dd, 1H, J4,5 1.26 Hz, H-4), 4.19 (m, 1H, H-50), 4.08 (m, 2H,
H-1), 4.05 (m, 2H, H-60), 4.04 (m, 1H, H-5), 3.92 and 3.64 (2dd, each
1H, Jgem 11.35 Hz, J5,6 3.78 Hz and 7.88 Hz, H-6), 2.13, 2.02, 2.00 and
1.90 (4s, each 3H, 4 ꢃ OAc), 1.29 (s, 6H, 2 ꢃ –CH3); 13C NMR
(DMSO-d6): d 100.2 (C-10), 75.6 (C-4), 75.4 (C-3), 74.8 (C-5), 72.2
(C-1), 70.0 (C-30), 69.8 (C-50), 68.7 (C-6), 68.4 (C-20), 67.0 (C-40),
61.0 (C-60), 22.0 (2 ꢃ –CH3), 20.6, 20.6, 20.4 and 20.2 (4 ꢃ OAc);
MALDI-TOFMS: Calcd for C23H32O14: 532. Found: 555 [M+Na]+,
571 [M+K]+.
1.6. 1,5-Anhydro-2,3-O-isopropylidene-4-O-b-(2,3,4,6-tetra-O-
acetyl-D-glucopyranosyl)-D-fructopyranose (7)
Coupling of donor 5 with acceptor 1 according to the general
procedure resulted in 7 (68%) as a syrup: ½a D25
ꢀ16.4 (c 1.0, CHCl3);
0 0
ꢂ
1H NMR (DMSO-d6): d 5.24 (dd, 1H, J2 ,3 9.66 Hz, J3 ,4 9.66 Hz, H-30),
0
0
4.99 (d, 1H, J1 ,2 8.14 Hz, H-10), 4.95 (dd, 1H, J4 ,5 9.66 Hz, H-40),
4.79 (dd, 1H, H-20), 4.21 and 4.03 (2dd, each 1H, Jgem 12.30 Hz,
1.10. 1,5-Anhydro-2,3-O-isopropylidene-4-O-b-
glucopyranosyl- -fructopyranose (11)
D
-
0
0
0
0
D
J5 ,6 4.41 Hz, and 2.21 Hz, H-60), 4.19 (m, 1H, H-4), 4.13 and 3.87
(2d, each 1H, Jgem 8.51 Hz, H-1), 4.08 and 3.97 (2m, each 1H, H-
6), 4.07 (d, 1H, J3,4 3.78 Hz, H-3), 3.97 (m, 1H, H-5), 3.93 (m, 1H,
H-50), 2.03, 1.98, 1.98 and 1.94 (4s, each 3H, 4 ꢃ OAc), 1.46 and
0
0
Zemplén deacylation of compound 7 according to the general
procedure resulted in 11 (80%) as a syrup: ½a D25
ꢀ18.4 (c 1.2, pyri-
ꢂ
dine); 1H NMR (DMSO-d6): d 5.08 (d, 1H, J2 ,OH 5.09 Hz, 20OH), 4.99
0
13
1.34 (2s, each 3H, 2 ꢃ –CH3); C NMR (DMSO-d6): d 97.8 (C-10),
(d, 1H, J3 ,OH 4.83 Hz, 30OH), 4.94 (d, 1H, J4 ,OH 5.34 Hz, 40OH), 4.34
0
0
83.9 (C-3), 80.2 (C-4), 71.7 (C-30), 70.5 (C-50), 70.4 (C-20), 70.2 (C-
5), 69.3 (C-1), 67.7 (C-40), 65.8 (C-6), 61.3 (C-60), 27.4 and 25.2
(d, 1H, J1 ,2 7.88 Hz, H-10), 4.29 (dd, 1H, J6 ,OH 4.83 Hz and 7.63 Hz,
60OH), 4.20 (m, 1H, H-4), 4.18 (d, 1H, H-3), 4.14 and 3.86 (2d, each
1H, Jgem 8.51 Hz, H-1), 4.07 and 3.94 (2m, each 1H, H-6), 4.06 (m,
1H, H-5), 3.66 and 3.44 (2m, each 1H, H-60), 3.13 (m, 2H, H-30
and H-50), 3.06 (m, 1H, H-40), 3.02 (m, 1H, H-20), 1.45 and 1.34
0
0
0
(2 ꢃ –CH3), 20.22 (4 ꢃ OAc); MALDI-TOFMS: Calcd for C23H32O14
:
532. Found: 555 [M+Na]+, 571 [M+K]+.
13
1.7. 1,5-Anhydro-2,3-O-isopropylidene-4-O-b-(2,3,4,6-tetra-O-
(2s, each 3H, 2 ꢃ –CH3); C NMR (DMSO-d6): d 101.6 (C-10), 84.8
acetyl-D-glucopyranosyl)-
D-tagatopyranose (8)
(C-3), 79.8 (C-4), 76.5 (C-30 and C-50), 73.2 (C-20), 70.0 (C-5), 69.9
(C-40), 69.4 (C-1), 66.1 (C-6), 61.0 (C-60), 27.5 and 25.2
(2 ꢃ –CH3). Anal. Calcd for C15H24O10: C, 49.45; H, 6.64. Found: C,
48.99; H, 6.47.
Coupling of donor 5 with acceptor 3 according to the general
procedure resulted in 8 (75%) as a syrup: ½a D25
ꢂ
+7.3 (c 0.8, CHCl3);

1018
K. Agoston et al. / Carbohydrate Research 344 (2009) 1014–1019
1.11. 1,5-Anhydro-2,3-O-isopropylidene-4-O-b-
glucopyranosyl- -tagatopyranose (12)
D
-
NMR (D2O): d 4.44 (d, 1H, J1 ,2 7.86 Hz, H-10), 3.89 (m, 1H, H-4),
3.85 and 3.65 (2m, each 2H, H-6 and H-60), 3.76 (m, 1H, H-3),
3.73 and 3.38 (2m, each 1H, H-1), 3.69 (m, 1H, H-5), 3.41 (m, 2H,
H-30 and H-50), 3.32 (m, 1H, H-40), 3.23 (m, 1H, H-20); 13C NMR
(D2O): d 102.9 (C-10), 92.5 (C-2), 78.8 (C-3), 76.1 (C-30 and C-50),
73.6 (C-20), 72.9 (C-1), 72.0 (C-5), 71.2 (C-40), 70.0 (C-4), 61.2 (C-6
and C-60). Anal. Calcd for C12H22O11: C, 42.11; H, 6.48. Found: C,
41.73; H, 6.42.
0
0
D
Zemplén deacylation of compound 8 according to the general
procedure resulted in 12 (85%) as a syrup: ½a D25
ꢂ
+5.8 (c 1, pyridine);
1H NMR (DMSO-d6): d 5.00 (d, 1H, J2 ,OH 5.04 Hz, 20OH), 4.95 (d, 1H,
0
J3 ,OH 4.72 Hz, 30OH), 4.89 (d, 1H, J4 ,OH 5.36 Hz, 40OH), 4.55 (dd, 1H,
0
0
0
J3,4 6.30 Hz, J4,5 1.58 Hz, H-4), 4.53 (d, 1H, H-3), 4.50 (dd, 1H, J6 ,OH
5.67 Hz and 5.99 Hz, 60OH), 4.20 (d, 1H, J1 ,2 7.57 Hz, H-10), 4.11 (m,
1H, H-5), 4.09 (m, 2H, H-1), 3.93 and 3.63 (2dd, each 1H, Jgem
11.35 Hz, J5,6 4.10 Hz and 7.57 Hz, H-6), 3.68 and 3.42 (2m, each
1H, H-60), 3.12 (m, 2H, H-30 and H-50), 3.02 (m, 1H, H-40), 2.96 (m,
1H, H-20), 1.29 (s, 6H, 2 ꢃ –CH3); 13C NMR (DMSO-d6): d 102.9 (C-
10), 76.5 (C-30 and C-50), 75.7 (C-5), 75.7 (C-3 and C-4), 73.1 (C-20),
72.3 (C-1), 69.9 (C-40), 67.9 (C-6), 60.7 (C-60), 26.2 (2 ꢃ –CH3). Anal.
Calcd for C15H24O10: C, 49.45; H, 6.64. Found: C, 49.87; H, 6.55.
0
0
1.16. 1,5-Anhydro-4-O-b-D-galactopyranosyl-D-fructose (17)
Acid hydrolysis of compound 13 according to the general pro-
cedure resulted in 17 (95%) as a glass: ½a D25
ꢀ21.2 (c 0.8, water);
ꢂ
1H NMR (D2O): d 4.28 (d, 1H, J1 ,2 7.88 Hz, H-10), 3.79 and 3.60
(2dd, each 1H, Jgem 12.30 Hz, H-60), 3.76 (m, 1H, H-50), 3.60 (m,
2H, H-6), 3.59 (m, 1H, H-5), 3.57 and 3.29 (2d, each 1H, Jgem
11.98 Hz, H-1), 3.54 (m, 1H, H-40), 3.50 (m, 1H, H-30) 3.49 (m,
1H, H-3), 3.38 (m, 1H, H-20), 3.37 (m, 1H, H-4); 13C NMR
(D2O): d 103.4 (C-10), 93.0 (C-2), 79.7 (C-4), 79.2 (C-3), 75.9 (C-
40 and C-5), 72.9 (C-30), 71.9 (C-1), 71.1 (C-20), 69.2 (C-50), 61.5
(C-6), 60.9 (C-60). Anal. Calcd for C12H22O11ꢁH2O: C, 40.00; H,
6.71. Found: C, 39.94; H, 6.72.
0
0
1.12. 1,5-Anhydro-2,3-O-isopropylidene-4-O-b-
galactopyranosyl- -fructopyranose (13)
D-
D
Zemplén deacylation of compound 9 according to the general
procedure resulted in 13 (85%) as a syrup: ½a D25
ꢀ28.4 (c 0.5, pyri-
ꢂ
dine); 1H NMR (DMSO-d6): d 4.90 (d, 1H, J2 ,OH 4.73 Hz, 20OH), 4.73
0
(d, 1H, J3 ,OH 5.67 Hz, 30OH), 4.38 (m, 2H, 40OH and 60OH), 4.28 (d,
1.17. 1,5-Anhydro-4-O-b-D-galactopyranosyl-D-tagatose (18)
0
1H, J1 ,2 7.56 Hz, H-10), 4.18 (m, 2H, H-4 and H-3), 4.15 and 3.86
(2d, each 1H, H-1), 4.08 and 3.98 (2m, each 1H, H-6), 4.05 (m, 1H,
H-5), 3.64 (m, 1H, H-40), 3.51 (m, 2H, H-60), 3.36 (m, 1H, H-50), 3.34
(m, 1H, H-20), 3.28 (m, 1H, H-30), 1.46 and 1.29 (2s, each 3H,
0
0
Acid hydrolysis of compound 14 according to the general proce-
dure resulted in 18 (96%) as a syrup. ½a D25
ꢂ
ꢀ6.4 (c 0.5, water); 1H
NMR (D2O): d 4.38 (d, 1H, J1 ,2 7.89 Hz, H-10), 3.91 (m, 1H, H-4),
3.86 (m, 1H, H-40), 3.77 (m, 1H, H-3), 3.74 and 3.39 (2d, each 1H,
Jgem 11.98 Hz, H-1), 3.70 (m, 4H, H-6 and H-60), 3.69 (m, 1H, H-5),
3.63 (m, 1H, H-50), 3.58 (m, 1H, H-30), 3.47 (m, 1H, H-20); 13C
NMR (D2O): d 103.6 (C-10), 92.4 (C-2), 78.9 (C-3), 75.6 (C-50), 73.2
(C-30), 73.0 (C-1), 72.0 (C-5), 71.3 (C-20), 70.0 (C-4), 69.1 (C-40),
61.5 (C-6 and C-60). Anal. Calcd for C12H22O11: C, 42.11; H, 6.48.
Found: C, 41.70; H, 6.40.
0
0
13
2 ꢃ –CH3); C NMR (DMSO-d6): d 103.5 (C-10), 85.9 (C-3), 80.9
(C-4), 76.2 (C-50), 74.7 (C-30), 71.5 (C-20), 71.2 (C-5), 70.7 (C-1), 69.2
(C-40), 67.5 (C-6), 61.4 (C-60), 28.8 and 26.1 (2 ꢃ –CH3). Anal. Calcd
for C15H24O10: C, 49.45; H; 6.64. Found: C, 49.11; H, 6.61.
1.13. 1,5-Anhydro-2,3-O-isopropylidene-4-O-b-
galactopyranosyl- -tagatopyranose (14)
D-
D
Zemplén deacylation of compound 10 according to the general
References
procedure resulted in 14 (76%) as a syrup: ½a D25
ꢀ16.4 (c 0.6, pyri-
ꢂ
dine); 1H NMR (DMSO-d6): d 4.83 (d, 1H, J2 ,OH 4.73 Hz, 20OH), 4.70
0
1. Andersen, S. M.; Lundt, I.; Marcussen, J.; Yu, S. Carbohydr. Res. 2002, 337, 873–
890.
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3. (a) Yu, S.; Christensen, T. M.; Kragh, K. M.; Bojsen, K.; Marcussen, J. Biochim.
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9497.
(d, 1H, J3 ,OH 5.36 Hz, 30OH), 4.55 (m, 3H, 40OH, H-3 and H-4), 4.33
0
(dd, 1H, J6 ,OH 4.41 Hz and 10.09 Hz, 60OH), 4.15 (d, 1H, J1 ,2 7.25 Hz,
H-10), 4.09 (m, 3H, H-1 and H-5), 3.90 and 3.46 (2m, each 1H, H-6),
3.61 (m, 1H, H-40), 3.50 (m, 2H, H-60), 3.32 (m, 1H, H-50), 3.28 (m,
1H, H-20), 3.25 (m, 2H, H-30), 1.31 and 1.30 (2s, each 3H,
0
0
0
13
2 ꢃ –CH3); C NMR (DMSO-d6): d 103.2 (C-10), 75.4 (C-3 and
C-4), 74.8 (C-50), 74.6 (C-5), 73.1 (C-30), 72.1 (C-1), 69.9 (C-20),
67.9 (C-40), 67.5 (C-6), 60.2 (C-60), 26.3 and 25.5 (2 ꢃ –CH3). Anal.
Calcd for C15H24O10: C, 49.45; H; 6.64. Found: C, 49.21; H, 6.71.
6. Fujisue, M.; Yoshinaga, K.; Muroya, K.; Abe, J.; Hizukuri, S. J. Appl. Glycosci. 1999,
46, 439–444.
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Asymmetry 2008, 19, 358–373.
1.14. 1,5-Anhydro-4-O-b-D-glucopyranosyl-D-fructose (15)
Acid hydrolysis of compound 11 according to the general proce-
dure resulted in 15 (95%) as a glass: ½a D25
ꢂ
ꢀ21.0 (c 0.5, water); 1H
NMR (D2O): d 4.44 (d, 1H, J1 ,2 7.88 Hz, H-10), 3.88 and 3.69 (2m,
each 2H, H-60 and H-6), 3.68 and 3.40 (2m, each 1H, H-1), 3.62
(m, 1H, H-3), 3.59 (m, 1H, H-4), 3.47 (m, 1H, H-5), 3.45 (m, 2H,
H-30 and H-50), 3.35 (m, 1H, H-40) 3.25 (m, 1H, H-20); 13C NMR
(D2O): d 102.9 (C-10), 92.9 (C-2), 79.7 (C-5), 79.3 (C-4), 76.0 (C-30
and C-50), 75.8 (C-3), 73.7 (C-20), 72.0 (C-1), 70.1 (C-40), 61.0 (C-6
and C-60). Anal. Calcd for C12H22O11ꢁH2O: C, 40.00; H, 6.71. Found:
C, 40.09; H, 6.65.
0
0
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1.15. 1,5-Anhydro-4-O-b-D-glucopyranosyl-D-tagatose (16)
Acid hydrolysis of compound 12 according to the general proce-
dure resulted in 16 (96%) as a syrup: ½a D25
ꢂ
+3.6 (c 0.6, water); 1H

K. Agoston et al. / Carbohydrate Research 344 (2009) 1014–1019
1019
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