A new type of rearrangement in branched-chain carbohydrates: Isomerization of 3-C-branched aldoses

Article abstract of DOI:10.1016/j.carres.2012.12.014

A new type of rearrangement is described for 3-C-branched chain aldoses. The studied transformation is based on the Mo(VI)-catalyzed isomerization of carbohydrate carbon skeleton and allows preparation of C-3 isomers of 3-C-branched aldoses in a simple wa

Full text of DOI:10.1016/j.carres.2012.12.014

Carbohydrate Research 370 (2013) 1–8
Contents lists available at SciVerse ScienceDirect
Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
A new type of rearrangement in branched-chain carbohydrates:
isomerization of 3-C-branched aldoses
⇑
Zuzana Hricovíniová , Miloš Hricovíni
Institute of Chemistry, Slovak Academy of Sciences, SK-845 38 Bratislava, Slovakia
a r t i c l e i n f o
a b s t r a c t
Article history:
A new type of rearrangement is described for 3-C-branched chain aldoses. The studied transformation is
based on the Mo(VI)-catalyzed isomerization of carbohydrate carbon skeleton and allows preparation of
C-3 isomers of 3-C-branched aldoses in a simple way without formation of side products. This rearrange-
ment at C-3 carbon differs from the previously described epimerization at C-2 of aldoses catalyzed by
Mo(VI) ions, known as Bílik reaction. The potential of this new transformation is illustrated on the
Received 7 August 2012
Accepted 17 December 2012
Available online 25 December 2012
Dedicated to the memory of Professor S. J.
Angyal (1914–2012)
preparation of new, 3-C-methyl-
3-C-vinyl- -allose, respectively.
D
-glucose and 3-C-vinyl-
D-glucose from 3-C-methyl-
D-allose and
D
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
Isomerization
Carbohydrate
Mo(VI)-catalysis
Microwave irradiation
Branched aldose
1. Introduction
drate carbon skeleton in microwave field.10,11 Unsubstituted mono-
saccharides create various types of complexes with molybdate ions
in aqueous solutions.12 Comprehensive studies of acyclic dimolyb-
date–saccharide complexes carried out by Bílik led to preparative
method for the synthesis of rare aldoses.13,14 The Bílik reaction ap-
plied to 2-ketoses yielded 2-C-hydroxymethyl-aldoses and vice ver-
sa. Epimerization reaction, during which C-1 to C-2 transposition
occurs,14 must involve catalytically productive complexes. Apart
from these highly reactive, catalytically active complexes a variety
of other, non-active complexes exist in aqueous solution as well.
Recent works from our laboratory have shown that microwave
irradiation has a great impact on this type of transformations. The
finding that the use of molybdate ions as catalyst in combination
with microwave irradiation improves the stereoselectivity mark-
edly and shortens the reaction time significantly has rendered
these reactions attractive for synthetic purposes. The methodology
is reliable for the preparation of many sugar derivatives and led to
the efficient preparation of epimeric aldoses,10 ketoses,11 deoxyal-
doses,15 and (1?6)-linked disaccharides,16 but it is also effective in
the case of aldoses bearing nitrogen in the branch.17
Branched-chain sugars represent a rare class of naturally occur-
ring carbohydrates. They are all characterized by modification at
one of the non-terminal carbon atoms of the sugar chain. Such
derivatives often show unique structural characteristics that are
associated with notable biolological activity.1,2 The oldest and the
best-known examples of branched-chain sugars are
(3-C-hydroxymethyl- -glycero-tetrose) and -hamamelose (2-C-
hydroxymethyl-
D-apiose
D
D
D
-ribose) which were isolated from plants as a
structural component of apiin3 and hammamelitannin.4 Subse-
quently, numerous other compounds have been isolated from nat-
ural sources or synthesized.5–7 Especially 3-C-methyl-branched
sugars, such as L D-evalose, L-streptose, and D-virenose,
-mycarose,8
are glycosidic components of antibiotics9 and have stimulated
extensive research on their synthesis. Methods of introducing a
carbon chain at branching carbon atom require several steps. In
spite of strong demands for higher stereoselectivities, an interest-
ing and potentially valuable alternative is the stereospecific isom-
erization of carbohydrate carbon skeleton catalyzed by transition-
metals. Such reactions allow even transformations of complex or-
ganic molecules.
The biological importance of 3-C-branched chain aldoses and
the unexplored potential of this transformation prompted us to
investigate whether C-3 isomerization could be performed to syn-
thesize biologically important saccharides. The feasibility of such
transformation employing Mo(VI) catalyst in combination with
microwave field has been verified on various 3-C-branched chain
aldoses preparing their isomeric structures.
During the past decade we have demonstrated the advantages
and effectiveness of Mo(VI)-catalyzed rearrangement of carbohy-
⇑
Corresponding author. Tel: +421 2 59410282; fax: +421 2 59410222.
E-mail address: zuzana.hricoviniova@savba.sk (Z. Hricovíniová).
0008-6215/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.carres.2012.12.014

2
Z. Hricovíniová, M. Hricovíni / Carbohydrate Research 370 (2013) 1–8
Table 1
Comparison of microwave and conduction-heated samples of the Mo(VI) catalyzed isomerization of 3-C-branched aldoses. Conversions are shown also for conventional heating to
demonstrate vast differences between microwave and conventional approaches in reaction kinetics and amounts of isomeric product formation
3-C-Branched aldose
Microwave field
3-C-Aldose (%)
Oil-bath heating
3-C-Aldose (%)
Changes in reaction rate
Time (min)
Time (h)
3-C-Methyl-
3-C-Vinyl- -allose (7)
3-C-Phenyl- -allose (8)
3-C-Nitromethyl- -glucose (9)
3-C-Cyano- -glucose (10)
D
-allose (6)
5
5
10
10
10
19
14
—
—
—
10
12
15
15
15
9
8
—
—
—
120ꢀ
144ꢀ
—
—
—
D
D
D
D
2.2. Mo(VI)-catalyzed isomerization reaction
2. Results and discussion
2.1. Synthesis of model 3-C-branched chain aldoses
Due to the multiple donor sites of nearly equivalent oxygen
atoms and due to the equilibria between several isomers,
branched-chain aldoses are versatile ligands. They may exist in
aqueous solution in pyranose and furanose forms but in acyclic
form as well. Furthermore, different conformers of furanose and
pyranose rings provide different modes for metal binding.20
Molybdate ions could form catalytically active species promoting
stereospecific rearrangement of the saccharide carbon skeleton.
Complexes with sugars are formed only when three or more hy-
droxyl groups are available in the current relative positions. The
acyclic hydrated aldehyde forms of aldoses are linked in the binu-
clear molybdate core as tetradentate ligands via their hydrated car-
Five model 3-C-branched chain aldoses with different struc-
tures were synthesized using Grignard reaction, which has the po-
tential to cause branching of the carbohydrate skeleton. The
corresponding 1,2: 5,6-di-O-isopropylidene-3-C-methyl-
(1), 1,2: 5,6-di-O-isopropylidene-3-C-vinyl- -allose (2) and 1,2:
5,6-di-O-isopropylidene-3-C-phenyl- -allose (3) was thus prepared
in 84%, 81% and 87% yield respectively. Another two 3-C-branched
D-allose
D
D
sugars, 1,2: 5,6-di-O-isopropylidene-3-C-nitromethyl-
D
-glucofura-
-glucofura-
nose (4) and 3-C-cyano-1,2: 5,6-di-O-isopropylidene-
D
nose (5), were prepared according to literature.18,19 The
structures of 4 and 5 were confirmed by spectroscopic methods.
Acid-catalyzed hydrolysis of the isopropylidene derivatives 1–5
led exclusively to the corresponding 3-C-branched aldoses 6–10
respectively in very good yields (Scheme 1).
bonyl group and three adjacent hydroxyls (bound on carbons C(2)
(3), and C(4)) (Fig. 1). Only these forms are active and mediate the
stereospecific rearrangement.
,
C
Model compounds 6–10 were used to investigate Mo(VI)-cata-
lyzed stereospecific isomerizations with C-3 branched sugars.
The experiments were carried out with controlled microwave irra-
diation under sealed vessel conditions. The influence of microwave
irradiation on conversion, selectivity, and product distribution was
examined using multimode microwave reactor consisting of a con-
tinuous focused microwave power delivery system with operator-
selectable power. The 3-C-branched chain aldose was suspended in
0.2% aqueous solution of molybdic acid and the mixture was ex-
posed to microwave radiation at a controlled power (300 W). A
homogenous blue solution was obtained indicating the complex
Two characteristic doublet resonances at 5.09 ppm and at
4.79 ppm originated from anomeric protons of a- and b-pyranose
forms in 1H NMR spectrum of 3-C-methyl-
D-allose (6). The ratio
of these forms was determined from the 1H resonance intensities
and indicated that the b-pyranose form is more stable than the
a-form in aqueous solution (17% a-pyranose, 83% b-pyranose).
The presence of the methyl group at C-3 was confirmed by the
characteristic 1H resonance (1.31 ppm) (CH3 (C-3)); 13C resonance
(CH3 (C-3)) was at 20.99 ppm. Three bond proton-proton coupling
constant between H-1 and H-2 (3J1,2) was 8.1 Hz for the b-pyranose
form, thus in a good agreement with 4C1 form of the pyranose ring.
The structure of 6 has been confirmed by 2D COSY, HSQC, and
HMBC methods. Similarly, the b-pyranose form is more stable than
formation. We have observed that 3-C-methyl-
3-C-vinyl- -allose (7) are rapidly interconverted to their isomers,
3-C-methyl- -glucose (11) and 3-C-vinyl- -glucose (12) under
D-allose (6) and
D
D
D
present experimental conditions. The equilibruim mixtures
favored in both cases the allo-isomer. Highly stereoselective reac-
tion could be accomplished with a catalytic amount of Mo(VI) ions
in few minutes (Scheme 2). It should be stressed that the reaction
proceeded without significant formation of secondary products.
Transformation must involve the formation of catalytically active
dimolybdate species as intermediates which enable the stereospe-
cific rearrangement in catalytic cycle. Experimental data have
shown that 3-C-branched aldoses gave rise to new stereoisomeric
branched compounds.
the
allose (7). 1H chemical shift of anomeric proton of the prevailing
b form is at 4.89 ppm; chemical shift of proton of the form is
at 5.15 ppm. Three characteristic multiplets at lower field
(5.84 ppm, 5.42 ppm, and 5.39 ppm) are due to the vinyl group
linked to C-3 carbon. Corresponding vinyl carbon resonances are
at 138.66 ppm (CH) and 117.39 (CH2).
a-form (15% a-pyranose, 85% b-pyranose) also in 3-C-vinyl-D-
a
Slightly higher population of the
pyranose, 79% b-pyranose), compared to previous compounds, in
3-C-phenyl-
-allose (8) has been determined from 1H NMR spectra.
The bulky phenyl group affected not only the mentioned anomeric
ratio but in part also chemical shifts of anomeric protons ( -ano-
a-pyranose form (21% a-
D
The structure of 3-C-methyl-D-glucose (11) was identified on
the basis of NMR chemical shifts, proton-proton coupling constant
(3JH,H), NOEs and theoretical DFT analysis. 1H NMR spectrum of the
reaction mixture contained new doublets at 5.18 ppm and
4.66 ppm, respectively, which were assigned to the pyranose ano-
a
mer, 5.25 ppm; b-anomer 5.04 ppm). Three multiplets at 7.36-
7.55 ppm (1H spectrum) and four resonances namely, 128.56,
127.67, 125.86, and 120.99 ppm in 13C spectrum arose from the
phenyl group linked to C-3 carbon. Unlike to above mentioned
derivatives 6–8, all four forms were identified in 3-C-nitrometh-
meric protons H-1 of the 3-C-methyl-
gave the ratio of
/b 15/85 in aqueous solution at 25 °C. 3J1,2 value
was 8.2 Hz and was compatible with antiperiplanar position of H-1
and H-2 in 3-C-methyl-b- -glucose (Fig. 2). Theoretical analysis
D-glucose. Signal integration
a
yl-
D
-glucofuranose (9) in solution (31%
a
-pyranose, 19% b-pyra-
-furanose, 28% b-furanose)). Relatively high
-pyranose form (31% -pyranose, 69% b-pyranose)
-glucofuranose (10). The assign-
D
nose, 22%
population of
was observed also in 3-C-cyano-
a
made possible further insight into the product structure. DFT-opti-
mized molecular geometry using the 6-31+G⁄ basis set enabled cal-
culation of proton-proton coupling constants and inter-proton
distances. Computed torsion angle between H-1 and H-2 was
a
a
D
ments of NMR spectra were carried out using 2D NMR
spectroscopy.

Z. Hricovíniová, M. Hricovíni / Carbohydrate Research 370 (2013) 1–8
CH2OH
3
CH2OH
O
O
CH3
CH=CH2
OH
OH
HO
HO
HO
OH
HO
OH
6
7
O
O
f
f
O
O
O
CH3
O
O
O
O
HO
OH
O
1
a
b
2
O
O
O
O
O
O
O
O
c
O
O
O
O
Ph
OH
e
O
O
d
O
HO
O
N
C
3
O
O
5
f
O
OH
f
O
CH2OH
O
CH
2NO2
CH2OH
O
4
O
Ph
OH
OH
OH
HO
f
HO
HO
HO
OH
OH
CN
8
HO
10
O
OH
OH
OH
CH
2NO2
9
Scheme 1. Reagents and conditions: (a) CH3MgI, Et2O, 0 °C?rt/4 h; (b) CH@CH2MgBr, THF, 60 °C/3 h; (c) PhMgBr, Et2O, reflux, 2 h; (d) CH3NO2, CH3ONa, r t. 18 h; (e) NaCN,
CH3OH, rt 6 h; (f) H2O, Dowex 50 W ꢀ4, H+ 75 °C, 7 h.
characteristic 1H resonance (1.16 ppm) (CH3 (C-3)). Further evi-
O
O
O
O
dence of the gluco arrangement was found in NOESY spectra.
Cross-peaks between 3-C-methyl group and anomeric proton as
well as C-methyl and H-5 proton confirmed spatial closeness of
these protons (computed distances were 2.3–2.4 Å). These NOEs
could be observed only in case when methyl group is in the axial
position. On the other hand, dipolar interactions seen in NOESY
Mo
O
Mo
HO
O
O
O
O
H
C
OH
H
4
1
C
CH2OH
C
C
C
6
2
5
3
H
spectrum differed in 3-C-methyl-D-allose. In the latter case,
H
cross-peaks between C-methyl group and H-2 and H-4 protons
agreed with equatorial position of the C-methyl group (corre-
sponding computed internuclear distances were 2.5–2.6 Å).
The b-pyranose form (H-1 at 4.80 ppm) is more stable than the
H
Figure 1. The acyclic forms of aldoses linked in the binuclear molybdate core as
tetradentate ligands via their hydrated carbonyl group and three adjacent hydrox-
yls (bound on carbons C(2), C(3), and C(4)).
a-form (H-1 at 5.21 ppm) also in 3-C-vinyl-D-glucose (12) (28% a-
pyranose, 72% b-pyranose). The value of proton-proton coupling
3
178.9°, the angle between H-4 and H-5 was ꢁ175.2°. Theoretical
constant J1,2 was 8.6 Hz and was thus comparable with the value
values of three-bond coupling constants for these proton pairs
in 3-C-methyl-b-D
-glucose confirming the 4C1 b-pyranose form of
this branched glucose derivative. Three resonances at lower field
(6.03 ppm, 5.56 ppm, and 5.53 ppm) originate from the vinyl group
linked to C-3 carbon. Corresponding carbon resonances of vinyl
3
(3J1,2 = 7.9 Hz and J4,5 = 9.0 Hz) agreed with experimental data
and supported 4C1 b-pyranose form of glucose derivative. The
presence of the methyl group at C-3 was confirmed by the

4
Z. Hricovíniová, M. Hricovíni / Carbohydrate Research 370 (2013) 1–8
OH
H
OH
H
H
O
Mo(VI)
H
O
HO
H3C
HO
MW 5 min
OH
OH
HO
H
OH
H
OH
OH
H
CH3
H
6
11
OH
H
OH
H
H
O
Mo(VI)
H
O
HO
H2C=HC
HO
MW 5 min
OH
OH
HO
H
OH
H
OH
OH
H
H
H2C=CH
7
12
Scheme 2. Stereospecific Mo(VI)-catalyzed isomerisation of 3-C-methyl-D-allose (6) and 3-C-vinyl-D-allose (7) to 3-C-methyl-D-glucose (11) and 3-C-vinyl-D-glucose (12) in
microwave field.
Figure 2. High-resolution 600 MHz 1H NMR spectra of 3-C-methyl-
D-allose (a) and 3-C-methyl-D-glucose (b) at 25 °C in D2O. Insets show DFT-optimized structures of these
branched aldoses.
group are at 131.82 (CH) and 120.80 ppm (CH2). On the other hand,
in the case of 3-C-phenyl- -allose (8) any changes in the reaction
mixture were observed even after prolonged reaction time. Simi-
larly, there were no changes detected in the composition of the
cose and 3-C-vinyl-D-glucose were markedly lower (9% and 8%)
D
using conventional conditions. Furthermore, the analysis of 1H
NMR spectra indicated also formations of undesirable side prod-
ucts in the reaction mixture after long heating. These results sug-
gest that molybdate ions can form catalytically active complexes
with 3-C-branched chain aldoses thus promoting the isomerization
process. Mo(VI) acts as a unique catalyst for isomerization of car-
bohydrate skeleton and study of this rearrangement provides a
new route to the rare 3-C-branched chain aldoses. Alkyl groups
such as methyl, vinyl might have less steric demands on the reaction
transition state that leads to the desired isomeric molecule. Deriva-
reaction mixture for 3-C-nitromethyl-
D-glucose (9) and 3-C-cya-
no- -glucose (10). Thus, bulkier substituents at the branching po-
D
sition prevent isomerisation at C-3 carbon.
The isomerization reaction progressed smoothly in microwave
field and reached its thermodynamic equilibrium within 5 min,
compared to conventional conditions, where these reactions took
several hours to complete (Table 1). Transformation afforded de-
sired 3-C-methyl-
D
-glucose and 3-C-vinyl-
D
-glucose 120–144-
tives, 3-C-phenyl-D-allose, 3-C-nitromethyl-D-glucose, and 3-C-cya-
times faster than using conventional approach (90 °C, oil-bath).
The reaction yields are markedly improved (ꢂ100%) as well. The
no- -glucose were not suitable ligands for such transformation.
D
Bulky substituents most likely prevent formations of active dimolyb-
date species. Consequently, isomeric aldoses were not formed.
As we explored the scope of this reaction, some limitations have
been uncovered. Analysis of Bílik reaction showed that C-2 epimers
are formed due to C1–O1 and C2–C3 bonds cleavage with
best conversion was found with 3-C-methyl-D-allose (6) that
isomerize to 3-C-methyl-
irradiation. Similarly, 3-C-vinyl-
vinyl- -glucose (12) in 14% yield. The yields of 3-C-methyl-
D
-glucose (11) (19%) using microwave
-allose (7) provided product 3-C-
-glu-
D
D
D

Z. Hricovíniová, M. Hricovíni / Carbohydrate Research 370 (2013) 1–8
5
subsequent formations of C2–O1 and C1–C3 bonds via putative
binuclear tetradendate Mo(VI)-aldose complex.21 Present data
indicate that a specific active molybdate complex is formed pro-
ducing isomeric 3-C-methyl-branched aldose. This complex must
be different to that one described for C-2 epimerization (Fig. 1).
However, the structure of this complex and mechanism of this
new type of isomerisation reaction is not clear. At present we
can just consider that the presence of bulky substituent at C(3) car-
bon prevents formation of binuclear tetradendate complex due to
steric effects. In this case, steric effects drive Mo(VI) ions to adopt
a different complex structure contributing to rearrangement of
chemical bonds linking C(2), C(3), and C(4) carbons. The analysis of
structure of such complex will be subject of our further studies.
The structure of the ligand thus seems to be a key issue for the cat-
alytic process: Aldoses epimerize at C-2 carbon producing
epialdoses (Fig. 3a). Aldoses with substituents at C(2) carbon isom-
erize under the formation of 2-ketoses (Fig. 3b). 3-C-branched
aldoses with sterically accessible substituents (methyl, vinyl)
isomerize at C-3 carbon (Fig. 3c), whereas bulky substituents (phe-
nyl or nitromethyl group) linked to C(3) carbon completely prevent
any isomerization. They possibly inhibit formation of active com-
plexes or block the isomerisation reaction by creating stable or
nonreactive molybdate complexes.
yields at present and further refinement is in progress using differ-
ent experimental conditions (pH, temperature, ligand/catalyst ra-
tio). Study of mechanism of this transformation with 13C-labeled
compounds is currently under investigation and the results will
be discussed in further publications.
3. Conclusion
We have demonstrated that isomeric products of 3-C-methyl- and
3-C-vinyl-branched chain aldoses can be prepared via C-3 isomeriza-
tion utilizing the synergic effect of Mo(VI) ions and microwave field.
Examples of chemical transformations producing reasonable yields
are illustrated on the preparation of new 3-C-methyl-D-glucose and
3-C-vinyl- -glucose from 3-C-methyl- -allose and 3-C-vinyl-D
D
D
-allose.
The reaction is straightforward and leads to rare saccharides in a single
step, but is limited to smaller substituents in the branch. This approach
provides excellent alternative to conventional multistep methods in
chemical synthesis of rare carbohydrates and acquired knowledge in
this area may provide insight into the development of other stereose-
lective transformations used in the synthesis of natural products.
4. Experimental
4.1. General methods
These results also point out the important role of C(3) substitu-
tion in the pyranose ring, directing the new rearrangement path-
way. The transformation probably occurs via intramolecular
mechanism. This new type of isomerisation yielded only moderate
Conversions and the purities of the products were determined
by NMR spectroscopy. High-resolution NMR spectra were recorded
OH
H
OH
H
Mo(VI)
MW 3 min
H
O
OH
O
H
HO
a
HO
OH
H
OH
H
H
OH
OH
H
OH
H
D-altrose
epialdose
D-allose
aldose
OH
OH
H
H
CH2OH
OH
Mo(VI)
O
H
O
HO
HO
b
c
MW 3 min
CH2OH
H
OH
H
H
H
OH
OH
H
OH
H
2-C-Hydroxymethyl-D-allose
2-C-HMe-aldose
D-altro-heptulose
2-ketose
OH
H
OH
H
H
O
Mo(VI)
H
O
HO
CH3
HO
MW 5 min
OH
OH
HO
H
H
OH
OH
OH
H
CH3
H
3-C-Methyl-D-glucose
3-C-branched-D-aldose
3-C-Methyl-D-allose
3-C-branched-D-aldose
Figure 3. Isomerizations of aldoses and branched chain aldoses at C(2) and C(3) carbons catalyzed by Mo(VI). Aldoses epimerize at C(2) carbon producing corresponding epimer
(a). 2-C-Hydroxymethyl-aldoses with substituted at C(2) carbon isomerize to 2-ketoses14 (b). 3-C-branched aldoses with sterically accessible substituents (methyl, vinyl)
isomerize at C(3) carbon producing isomeric 3-C-branched aldoses (c).

6
Z. Hricovíniová, M. Hricovíni / Carbohydrate Research 370 (2013) 1–8
in a 5 mm cryoprobe at 25 °C in D2O, acetone-d6 or CDCl3. The pro-
ton and carbon chemical shifts were referenced to external TSP.
One-dimensional 600 MHz 1H and 150 MHz 13C NMR spectra as
well as two-dimensional COSY, HSQC, and HMBC were used to
determine 1H and 13C chemical shifts. Chemical shifts (d) are
quoted in ppm and coupling constants (J) in Hertz. The geometry
of compounds has been optimized with the GAUSSIAN09 pro-
gram22 using density functional theory (DFT) with the hybrid
B3LYP functional and the 6-31+G⁄ basis set. Solvent effect was
evaluated using the IEFPCM approach.23 NMR proton–proton
spin–spin coupling constants were computed with the B3LYP func-
tional. Microwave reactions were performed in a multimode
microwave reactor CEM Discover consisting of a continuous fo-
cused microwave power delivery system with operator-selectable
(C-5), 68.92 (C-6), 28.83, 28.71, 28.57, 27.42 (4 ꢀ CH3 Ip), 21.70
(CH3 (C-3)).
4.3. 1,2: 5,6-Di-O-isopropylidene-3-C-vinyl-
D-allo-furanose (2)
To the cold 0 °C solution of 1,2: 5,6-di-O-isopropylidene-
D
-ribo-
hex-3-ulose (1 g; 3.6 mmol) in dry THF (20 mL) was added drop-
wise with stirring a solution of 0.7 M vinylmagnesium bromide
in THF (16.7 mL; 11.7 mmol). Stirring continued at room tempera-
ture for 30 min. The yellow reaction mixture was heated at 60 °C
for 3 h. The mixture was cooled and complex was decomposed
with water. After addition of saturated aq. solution NH4Cl the reac-
tion mixture was extracted with CHCl3 (5 ꢀ 25 mL). The combined
organic layers were dried overnight (MgSO4). A syrupy derivative
was purified by flash column chromatography on silica gel (solvent
B). TLC indicated one major product 2 isolated as syrup. Yield
power from
0 to 300 W; microwave frequency source of
2.45 GHz. The reactions were performed in sealed glass tubes
and were stirred magnetically. FT-IR spectra were measured on
spectrometer Nicolet 6700 with DTGS detector and OMNIC 8.0
software using 128 scans at the resolution of 4 cmꢁ1 with diamond
ATR technique. MS were measured on ITQ 900 Thermo Fisher (EI,
70 eV). Optical rotations were determined at 20 °C with an auto-
matic polarimeter Perkin–Elmer Model 141 using a 10 cm, 1-ml cell.
The progress of reactions was checked by thin layer chromatog-
raphy (TLC) on Merck silica gel 60 glass plates. Detection was ef-
fected by spraying the chromatograms with 10% ethanolic
sulfuric acid and heating them to 100 °C. Flash column chromatog-
839 mg (81%); Rf = 0.88 (solvent B); ½a D20
ꢃ
+32.0 (c = 1, CHCl3); mmax
(ATR, diamond): 3101 cmꢁ1 (@CH), 1638 cmꢁ1 (C@C); MS (EI,
70 eV); m/z: 287 [M++H], calcd for C14H22O6 286.3209; 1H NMR
(599.84 MHz, acetone-d6): 5.83 (d, 1H, J1 ,2 a = 10.9 Hz, H-10 vinyl),
0
0
5.78 (d, 1H, J1,2 = 3.8 Hz, H-1), 5.57 (dd, 1H, J2 a,2 b = 1.3 Hz, H-20a vi-
0
0
nyl), 5.37 (dd, 1H, J1 ,2 b = 17.3 Hz, H-20b vinyl), 4.27 (d, 1H, H-2),
0
0
0
4.10 (m, 1H, H-5), 4.03 (dd, 1H, J5,6 = 6.2 Hz, J6,6 = 8.5 Hz, H-6),
3.92 (d, 1H, J4,5 = 7.3 Hz, H-4), 3.92 (dd, 1H, J5,6 = 5.6 Hz, H-60),
0
1.62 (s, 3H, CH3 (Ip)), 1.44 (s, 3H, CH3 (Ip)), 1.35 (s, 3H, CH3 (Ip)),
1.32 (s, 3H, CH3 (Ip)). 13C NMR (150.84 MHz, acetone-d6): 134.82
(–CH Vi), 116.82 (–CH2 Vi), 113.13 (1,2 CMe2), 109.41 (5,6 CMe2),
103.81 (C-1), 83.68 (C-2), 81.41 (C-4), 80.33 (C-3), 73.83 (C-5),
67.08 (C-6), 26.71, 26.67, 26.44, 25.27 (4 ꢀ CH3 Ip).
raphy was performed with silica gel (40–100 lm, Merck). Solvent
A (ethyl acetate/hexane/acetone, 6:1:2, v/v/v); solvent B (ethyl ace-
tate/chloroform, 1:1 v/v); solvent C (diethyl ether/hexane, 1:1, v/
v); solvent D (ethyl acetate/benzene, 1:1, v/v). Separations of the
free sugars were accomplished by column chromatography on
Dowex 50 W X8 resin (Sigma–Aldrich) in the Ba2+ form (200–
400 mesh). Paper chromatography was performed by the descend-
ing method on the Whatman No. 1 paper using ethyl acetate/pyr-
idine/water (8:2:1) as the mobile phase. The chromatograms were
made visible by means of alkaline silver nitrate. All chemicals were
reagent grade and used without further purification. All concentra-
tions were carried out under reduced pressure at a bath tempera-
ture not exceeding 50 °C.
4.4. 1,2: 5,6-Di-O-isopropylidene-3-C-phenyl-D-allo-furanose (3)
To the cold 0 °C solution of 1,2: 5,6-di-O-isopropylidene-
D-
ribohex-3-ulose (300 mg; 1.1 mmol) in dry diethyl ether (6 mL)
was added dropwise with stirring a solution of 2.8 M phenylmag-
nesium bromide in diethyl ether (1.3 mL; 3.6 mmol). Stirring con-
tinued at room temperature for 20 min. The yellow reaction
mixture was refluxed for 2 h. The mixture was cooled and com-
plex was decomposed with water. After addition of saturated
aq solution NH4Cl (5 mL) the reaction mixture was extracted
with CHCl3 (3 ꢀ 20 mL). The combined organic layers were dried
overnight (MgSO4) and syrupy derivative was purified by flash
column chromatography on silica gel (solvent C). TLC indicated
one major product 3 isolated as syrup. Yield 317 mg (87%);
4.2. 1,2: 5,6-Di-O-isopropylidene-3-C-methyl-D-allo-furanose
(1)
To the mixture of 1,2: 5,6-di-O-isopropylidene-D-ribohex-3-
ulose (1 g; 3.6 mmol) in dry diethyl ether (10 mL) cooled to 0 °C
was added dropwise with stirring 3 M solution of methylmagne-
sium iodide in diethyl ether (4 mL; 12 mmol) and stirring contin-
ued (0 °C?rt) 30 min. Reaction mixture was refluxed for 4 h until
the disappearance of starting material on TLC (solvent A). The com-
plex was decomposed with water. After addition of saturated aq
solution NH4Cl (10 mL) the reaction mixture was extracted with
CHCl3 (3 ꢀ 25 mL). The combined organic layers were dried over-
night (MgSO4) and concentrated in vacuo. TLC of the reaction mix-
ture indicated one major product which was purified by silica gel
flash column chromatography (solvent A) to afford the compound
1 (832 mg; 84%) isolated as syrup. Yield (84%); Rf = 0.81 (solvent
Rf = 0.60 (solvent C); ½a D20
ꢃ
+42.0 (c = 1, CHCl3); mmax (ATR, dia-
mond): 3091, 3061, 3037 cmꢁ1 (CH)Ar, 1603, 1583 cmꢁ1 (C–C)Ar
;
MS (EI, 70 eV); m/z: 337 [M++H], 77 [C6H5+], calcd. for C18H24O6
336.3796; 1H NMR (599.84 MHz, CDCl3): 7.37-6.82 (m, 5H, Ph
(C-3)), 6.09 (d, 1H, J1,2 = 4.0 Hz, H-1), 4.49 (d, 1H, H-2), 4.15 (d,
1H, J4,5 = 5.3 Hz, H-4), 3.80 (m, 1H, H-5), 3.55 (dd, J5,6 = 6.6 Hz,
J6,6 = 8.6 Hz, H-6), 3.13 (dd, 1H, J5,6 = 6.7 Hz, H-60), 1.67 (s, 3H,
CH3 (Ip)), 1.41 (s, 3H, CH3 (Ip)), 1.38 (s, 3H, CH3 (Ip)), 1.20 (s,
3H, CH3 (Ip)). 13C NMR (150.84 MHz, CDCl3): 112.90 (1,2 CMe2),
108.66 (5,6 CMe2), 104.86 (C-1), 84.40 (C-2), 83.23 (C-4), 80.38
(C-3), 73.63 (C-5), 65.20 (C-6), 26.55, 26.55, 26.52, 25.36
(4 ꢀ CH3 Ip).
0
0
A); ½a 2D0
ꢃ
+23.0 (c = 1, CHCl3); mmax (ATR, diamond): 3477 cmꢁ1
(OH), ms 2981 (CH3), mas 2885 (CH3), d 1458 (CH3), d 1373 (CH3);
MS (EI, 70 eV); m/z: 274 [M+], 259 [M+ꢁCH3], calcd for C13H22O6
274.3102; 1H NMR (599.84 MHz, acetone-d6): 5.73 (d, 1H,
J1,2 = 3.6 Hz, H-1), 4.15 (d, 1H, H-2), 4.12 (m, 1H, H-5), 4.00 (dd,
4.5. 1,2: 5,6-Di-O-isopropylidene-3-C-nitromethyl-
D-gluco-
furanose18 (4)
Yield 260 mg (75%); Rf = 0.86 (solvent B); ½a D20
ꢃ
+32.0 (c = 1,
1H, J5,6 = 6.1 Hz, J6,6 = 8.0 Hz, H-6), 3.88 (d, 1H, J4,5 = 6.1 Hz, H-4),
CHCl3); mmax (ATR, diamond): 3454 cmꢁ1 (OH), mas 1566 cmꢁ1
(NO2); ms 1377 cmꢁ1 (NO2); in accordance with lit.18 MS (EI,
70 eV); m/z: 320 [M++H] calcd for C13H21O8N 319.3077. Following
NMR data are given for the sake of completeness: 1H NMR
(599.84 MHz, CDCl3): 5.92 (d, 1H, J1,2 = 3.5 Hz, H-1), 4.92 (d, 1H,
0
3.83 (dd, 1H, J5,6 = 6.2 Hz, H-60), 1.49 (s, 3H, CH3 (Ip)), 1.34 (s, 3H,
0
CH3 (Ip)), 1.30 (s, 3H, CH3 (Ip)), 1.29 (s, 3H, CH3 (Ip)), 1.13 (s, 3H,
CH3 (C-3)). 13C NMR (150.84 MHz, acetone-d6): 114.50 (1,2; 5,6
CMe2) 106.25 (C-1), 87.52 (C-2), 84.16 (C-4), 79.57 (C-3), 76.57

Z. Hricovíniová, M. Hricovíni / Carbohydrate Research 370 (2013) 1–8
7
JCH2a, CH2b = 13.4 Hz, CH2a (NMe)), 4.73 (d, 1H, CH2b (NMe)), 4.59 (d,
3.66 (d, 1H, H-2). 13C NMR (150.84 MHz, D2O): 128.56, 127.67,
125.86, 120.99 (C6H5 (C-3)), 94.37 (C-1), 78.59 (C-3), 75.32 (C-2),
74.85 (C-5), 71.07 (C-4), 61.43 (C-6).
0
1H, H-2), 4.38 (m, 1H, J4,5 = 8.8 Hz, J5,6 = 2.9 Hz, J5,6 = 7.7 Hz H-5),
4.15 (dd, J6,6 = 8.7 Hz, H-6), 3.99 (dd, 1H, H-60), 3.68 (d, 1H, H-4),
0
1.52 (s, 3H, CH3 (Ip)), 1.43 (s, 3H, CH3 (Ip)), 1.35 (s, 3H, CH3 (Ip)),
1.31 (s, 3H, CH3 (Ip)).13C NMR (150.84 MHz, CDCl3): 113.07 (1,2
CMe2), 109.84 (5,6 CMe2), 104.86 (C-1), 85.36 (C-2), 81.33 (C-4),
79.67 (C-3), 71.76 (C-5), 67.31 (C-6), 26.93, 26.83, 26.28, 24.95
(4 ꢀ CH3 Ip).
4.11. 3-C-Nitromethyl-D-glucose (9)
Yield 95%; ½a 2D0
ꢃ
+26.0 (c = 1, H2O) (24 h); mmax (ATR, diamond):
3336 cmꢁ1 (OH); mas 1549 cmꢁ1 (NO2); ms 1379 cmꢁ1 (NO2); MS
(EI, 70 eV); m/z: 241 [M++H], calcd for C7H13O8N 240; 13C NMR
4.6. 3-C-Cyano-1,2: 5,6-Di-O-isopropylidene-
D
-gluco-furanose19
(150.84 MHz, D2O): 102.43 (C-1bf), 96.82 (C-1
91.27 (C-1 p), 81.02 (C-4bf), 81.02 (C-3 f), 80.27 (C-3bf), 79.82
(C-2bf), 78.77 (C-4 f), 76.86 (CH2bf), 76.86 (CH2 f), 76.64 (C-
3bp), 76.18 (C-2bp), 76.02 (CH2 p), 75.80 (C-3 p), 75.64 (CH2bp),
75.47 (C-2 f), 74.27 (C-5bp), 72.74 (C-4 p), 71.86 (C-4bp), 71.43
(C-2 p), 71.04 (C-5 p), 69.46 (C-5bf), 68.70 (C-5 f), 63.56 (C-
6bf), 63.56 (C-6 f), 61.04 (C-6bp), 60.67 (C-6 p).
af), 93.77 (C-1bp),
(5)
a
a
a
a
Yield 421 mg (41%); Rf = 0.79 (solvent D); ½a D20
ꢃ
+42.0 ? +47.0
a
a
(c = 1, acetone);19 Following analytical data are given for the sake
of completeness: mmax (ATR, diamond): 3365 cmꢁ1 (OH),
1375 cmꢁ1 (CN); MS (EI, 70 eV); m/z: 286 [M++H] calcd for
C13H19O6N 285.2931; 1H NMR (599.84 MHz, CDCl3): 5.97 (d, 1H,
J1,2 = 3.6 Hz, H-1), 4.69 (d, 1H, H-2), 4.34 (m, 1H, J4,5 = 7.6 Hz,
a
a
a
a
a
a
a
4.12. 3-C-Cyano-D-gluco-pyranose (10)
0
J5,6 = 4.3 Hz, J5,6 = 6.3 Hz, H-5), 4.15 (d, 1H, H-4), 4.09 (dd,
J6,6 = 8.8 Hz, H-6), 3.95 (dd, 1H, H-60), 1.51 (s, 3H, CH3 (Ip)), 1.41
Yield 93%; ½a 2D0
ꢃ
+20.0 ? +15.0 (c = 1, H2O) (24 h); mmax (ATR, dia-
0
(s, 3H, CH3 (Ip)), 1.33 (s, 3H, CH3 (Ip)), 1.30 (s, 3H, CH3 (Ip)). 13C
NMR (150.84 MHz, CDCl3): 112.92 (1,2 CMe2), 109.32 (5,6 CMe2),
105.11 (C-1), 85.85 (C-2), 82.75 (C-4), 74.22 (C-3), 71.91 (C-5),
66.34 (C-6), 26.29, 26.12, 25.77, 24.62 (4xCH3 Ip).
mond): 3288 cmꢁ1 (OH),1485 (CN); MS (EI, 70 eV); m/z: 206
[M++H], calcd for C7H11O6N 205.1653; 1H NMR (599.84 MHz,
D2O): 5.23 (d, 1H, H-1
3.87 (dd, 1H, H-6b), 3.81 dd, 1H, H-6
(m, 1H, H-60b), 3.77 (m, 1H, H-2
), 3.72 (m, 1H, H-5b), 3.71 (m,
1H, H-4b), 3.71 (m, 1H, H-4
), 3.41 (d, 1H, H-2b). 13C NMR
(150.84 MHz, D2O): 117.24 (s, CN (C-3)), 94.81 (C-1b), 91.41 (C-
), 77.95 (C-3b), 75.32 (C-3 ), 74.94 (C-5b), 74.32 (C-2b), 72.13
(C-2 ), 70.30 (C-4 ), 70.29 (C-4b), 69.76 (C-5 ), 60.34 (C-6b),
60.16 (C-6 ).
a
), 4.79 (d, 1H, H-1b), 3.90 (m, 1H, H-5
a),
a
), 3.79 (dd, 1H, H-60a), 3.72
a
4.7. Typical procedure for acid hydrolysis
a
A mixture of isopropylidene derivative of 3-C-branched chain
aldose in water and Dowex 50 W X4 resin in the H+ form was stir-
red at 75 °C for 7 h. The resin was filtered off, the filtrate was puri-
fied with charcoal, and evaporated to afford syrupy derivative.
1a
a
a
a
a
a
4.13. Typical procedure for Mo(VI) catalyzed isomerization of
the 3-C-branched chain aldoses
4.8. 3-C-Methyl-b-
D
-allo-pyranose (6)
Yield 96%; ½a 2D0
ꢃ
+9.6 ? +11.0 (c = 1, H2O) (24 h);
m
max (ATR, dia-
4.13.1. In microwave field
mond): 3299 cmꢁ1 (OH), ms 2976 (CH3), mas 2887 (CH3), d 1454
(CH3), d 1373 (CH3); MS (EI, 70 eV); m/z: 195 [M++H], calcd for
C7H14O6 194.1825; 1H NMR (599.84 MHz, D2O): 4.79 (d, 1H,
J1,2 = 8.1 Hz, H-1), 3.86 (m, 1H, H-6), 3.70 (m, 1H, H-5), 3.67 (m,
1H, H-60), 3.33 (d, 1H, J4,5 = 9.9 Hz, H-4), 3.13 (d, 1H, H-2), 1.31 (s,
3H, CH3 (C-3)). 13C NMR (150.84 MHz, D2O): 93.98 (C-1), 74.75
(C-2), 74.49 (C-5), 73.83 (C-3), 70.16 (C-4), 61.44 (C-6), 20.99
(CH3 (C-3)).
To the mixture of branched-chain aldose 6–10 dissolved in
water molybdic acid was added (molar ratio 1:10). The reaction
mixture was exposed to microwave irradiation (300 W) for differ-
ent lengths of time. Samples (0.5 mL) were taken at selected inter-
vals (ꢁ1, 2, 3, 4, 5, 10 min), treated with Amberlite IRA-400 in the
HCO3 form (3 mL) to remove the catalyst. The composition of
the reaction mixture was determined by 1H NMR spectroscopy.
The rest of the reaction mixture was also treated batch-wise with
an excess of the ion-exchange resin, filtered off, washed with
water, and combined filtrates were evaporated. Fractionization of
the syrupy residue by column chromatography on Dowex 50 W
X8 in the Ba2+ form, eluted with water at a flow rate 5 mL/h, affor-
ded two isomeric 3-C-branched derivatives that were fully
characterized.
4.9. 3-C-Vinyl-b-
D-allo-pyranose (7)
Yield 93%; ½a 2D0
ꢃ
+4.0 ? +4.5 (c = 1, H2O) (24 h); mmax (ATR, dia-
mond): 3315 cmꢁ1 (OH), 2996 (@CH), 1641 cmꢁ1 (C@C); MS (EI,
70 eV); m/z: 207 [M++H], calcd. for C8H14O6 206.1932; 1H NMR
0
0
0
0
(599.84 MHz, D2O): 5.84 (dd, 1H, J1 ,2 a = 11.0 Hz, J1 ,2 b = 17.4 Hz,
H-10 vinyl), 5.42 (dd, 1H, J2 a,2 b = ꢂ0.4 Hz, H-20a vinyl), 5.39 (dd,
4.13.2. Conventional conditions
0
0
1H, H-20b vinyl), 4.89 (d, 1H, J1,2 = 8.1 Hz, H-1), 3.86 (dd, 1H,
To the aqueous solution of 3-C-branched chain aldose 6–10
molybdic acid was added (molar ratio 1:10). Reaction mixture
was heated in oil-bath at 90 °C for 10–15 h. The composition of
the reaction mixture was examined by 1H NMR spectroscopy until
the equilibrium mixture was reached. The reaction mixture was
stirred with Amberlite IRA-400 in the HCO3ꢁ form (15 mL). The fil-
trates were concentrated to syrup that was fractionated by column
chromatography.
0
J5,6 = 2.0 Hz, J6,6 = 12.1 Hz, H-6), 3.79 (m, 1H, H-5), 3.69 (dd, 1H,
J5,6 = 5.8 Hz, H-60), 3.52 (d, 1H, J4,5 = 8.0 Hz, H-4), 3.30 (d, 1H,
0
H-2). 13C NMR (150.84 MHz, D2O): 138.66 (–CH Vi), 117.39 (–CH2
Vi), 93.92 (C-1), 77.30 (C-3), 74.37 (C-2), 73.28 (C-5), 68.92 (C-4),
61.38 (C-6).
4.10. 3-C-Phenyl-b-
D-allose (8)
Yield 92%; ½a 2D0
ꢃ
+12.0 ? +8.0 (c = 1, H2O) (24 h);
mmax (ATR, dia-
4.14. 3-C-Methyl-b-D-gluco-pyranose (11)
mond): 3293 cmꢁ1 (OH), 3064, 3029, 2935 cmꢁ1 (CH)Ar, 1601,
1547 cmꢁ1 (C–C)Ar; MS (EI, 70 eV); m/z: 257 [M++H], 77 [C6H5+],
calcd for C12H16O6 256.2518; 1H NMR (599.84 MHz, D2O): 7.55–
7.36 (m, 5H, Ph (C-3)), 5.04 (d, 1H, J1,2 = 7.9 Hz, H-1), 3.94 (m, 1H,
H-5), 3.89 (m, 1H, H-6), 3.88 (m, 1H, H-4), 3.73 (m, 1H, H-60),
Yield 19%; ½a 2D0
ꢃ
+8.6 ? +7.1 (c = 1, H2O) (24 h); mmax (ATR, dia-
mond): 3315 cmꢁ1 (OH), ms 2982 (CH3), mas 2866 (CH3), d 1454
(CH3), d 1371 (CH3); MS (EI, 70 eV); m/z: 195 [M++H], calcd for
C7H14O6 194.1825; 1H NMR (599.84 MHz, D2O): 4.66 (d, 1H,

8
Z. Hricovíniová, M. Hricovíni / Carbohydrate Research 370 (2013) 1–8
4. Hartisch, C.; Kolodziej, H. Phytochemistry 1996, 42, 191–198.
0
J1,2 = 8.2 Hz, H-1), 3.84 (dd, 1H, J5,6 = 2.2 Hz, J6,6 = 12.3 Hz, H-6),
5. For isolation and synthesis of branched-chain sugars see: (a) Ryu, D. H.; Tan, C.-
H.; Rando, R. R. Bioorg. Med. Chem. Lett. 2003, 13, 901–903; (b) Yu, J.; Zhang, S.;
Li, Z.; Lu, W.; Cai, M. Bioorg. Med. Chem. 2005, 13, 353–361; (c) Hricovíniová, Z.
Synthesis 2001, 751–754.
6. Haddad, J.; Kotra, L. P.; Mobashery, S. In Glycochemistry Principles, Synthesis, and
Applications; Wang, P. G., Bertozzi, C. R., Eds.; Marcel Dekker: New York, 2001;
pp 307–424.
3.67 (dd, 1H, J5,6 = 5.6 Hz, H-60), 3.49 (ddd, 1H, J4,5 = 10.2 Hz, H-
0
5), 3.44 (d, 1H, H-4), 3.24 (d, 1H, H-2), 1.16 (s, 3H, CH3 (C-3)). 13C
NMR (150.84 MHz, D2O): 94.59 (C-1), 76.52 (C-2), 75.47 (C-3),
74.87 (C-5), 72.02 (C-4), 61.27 (C-6), 12.74 (CH3 (C-3)).
7. Wang, J.; Li, J.; Czyryca, P. G.; Chang, H.; Kao, J.; Chang, Ch.-W. T. Bioorg. Med.
Chem. Lett. 2004, 14, 4389–4393.
4.15. 3-C-Vinyl-b-
D-gluco-pyranose (12)
8. McGuire, J. M.; Boniece, W. S.; Higgens, C. E.; Hoehn, M. M.; Stark, W. M.;
Westhead, J.; Wolfe, R. N. Antibiot. Chemother. 1961, 11, 320–327.
9. For 3-C-branched-chain sugars as constituents of antibiotics see: (a) Kwon, Y.
T.; Lee, Y. J.; Lee, K.; Kim, K. S. Org. Lett. 2004, 6, 3901–3904; (b) Miller, M. W.
The Pfizer Handbook of Microbial Metabolites; McGraw-Hill: New York, 1961. pp.
37–38; (c) Grisebach, H.; Schmid, R. Angew. Chem. 1972, 84, 192–196; (d)
Yield 14%; ½a 2D0
ꢃ
+8.0 (c = 1, H2O) (24 h); mmax (ATR, diamond):
3323 cmꢁ1 (OH), 2991 (@CH), 1620 cmꢁ1 (C@C); MS (EI, 70 eV);
m/z: 207 [M++H], calcd. for C8H14O6 206.1932; 1H NMR
0
0
0
0
(599.84 MHz, D2O): 6.03 (dd, 1H, J1 ,2 a = 11.0 Hz, J1 ,2 b = 17.0 Hz,
H-10 vinyl), 5.56 (d, 1H, H-20a vinyl), 5.53 (d, 1H, H-20b vinyl),
4.80 (d, 1H, J1,2 = 8.6 Hz, H-1), 3.85 (dd, 1H, J5,6 = 1.0 Hz,
ˇ
Toman, R.; Škultéty, L.; Ftácek, P.; Hricovíni, M. Carbohydr. Res. 1998, 306, 291–
296.
10. Hricovíniová, Z. Carbohydr. Res. 2006, 341, 2131–2134.
J6,6 = 11.2 Hz, H-6), 3.69 (dd, 1H, J5,6 = 5.7 Hz, H-60), 3.63 (m, 1H,
H-5), 3.52 (d, 1H, J4,5 = 10.0 Hz, H-4), 3.33 (d, 1H, H-2). 13C NMR
(150.84 MHz, D2O): 131.82 (-CH Vi), 120.80 (-CH2 Vi), 94.41 (C-
1), 78.40 (C-3), 76.50 (C-2), 74.78 (C-5), 71.96 (C-4), 61.13 (C-6).
0
0
11. Hricovíniová, Z. Tetrahedron: Asymmetry 2008, 19, 204–208.
12. For Mo(VI) complexes see: (a) Alföldi, J.; Petruš, L.; Bílik, V. Coll. Czech. Chem.
Commun. 1978, 43, 1476–1480; (b) Matulová, M.; Bílik, V. Chem. Papers 1992,
46, 253–256; (c) Sauvage, J. P.; Chapelle, S.; Verchère, J. F. Carbohydr. Res. 1992,
237, 23–32; (d) Matulová, M.; Bílik, V. Carbohydr. Res. 1993, 250, 203–209; (e)
Chapelle, S.; Verchère, J.-F. Carbohydr. Res. 1995, 277, 39–50.
13. Bílik, V. Chem. Zvesti 1972, 26, 183–186. 187–189, 372–375.
14. Petruš, L.; Petrušová, M.; Hricovíniová, Z. In Topics in Current Chemistry.
Glycoscience: Epimerisation, Isomerisation and Rearrangement Reactions of
Acknowledgements
This research was supported by VEGA Grant 2/0087/11, SP
Grant 2003SP200280203, and in part by CEGreen I, supported by
the Research & Development Operational Programme funded by
the ERDF.
Carbohydrates; Springer: USA, 2001; Vol. 215, pp 15–41.
9
i
15. Hricov
niová, Z. Tetrahedron: Asymmetry 2009, 20, 1239–1242.
16. Hricovíniová, Z. Tetrahedron: Asymmetry 2008, 19, 1853–1856.
17. Hricovíniová, Z. Tetrahedron: Asymmetry 2010, 21, 2238–2243.
18. Rosenthal, A.; Ong, K. S.; Barker, D. Carbohydr. Res. 1970, 13, 113–125.
19. Rosenthal, A.; Cliff, B. L. Can. J. Chem. 1976, 54, 543–546.
20. Verchère, J. F.; Chapelle, S.; Xin, F.; Crans, D. C. Prog. Inorg. Chem. 1998, 44, 837–
945.
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