Synthesis of 5,6-dimodified open-chain D-fructose derivatives and their properties as substrates of bacterial polyol dehydrogenase

Article abstract of DOI:10.1016/S0957-4166(99)00526-1

5-Deoxy-5-fluoro-D-xylulose as well as a range of new 5,6-dimodified open-chain analogues of D-fructose, namely the 5,6-diazido-5,6-dideoxy, 6-azido-5,6-dideoxy, 6-azido-5,6-dideoxy-5-fluoro, 5,6-dideoxy-5-fluoro, 5,6-dideoxy-6-fluoro and 5,6-dideoxy-5,6-

Full text of DOI:10.1016/S0957-4166(99)00526-1

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 11 (2000) 607–620
Synthesis of 5,6-dimodified open-chain D-fructose derivatives and
their properties as substrates of bacterial polyol dehydrogenase
Philipp Hadwiger,a Peter Mayr,b Bernd Nidetzky,b Arnold E. Stütz a,∗ and Andreas Tauss a
aGlycogroup, Institut für Organische Chemie der Technischen Universität Graz, Stremayrgasse 16, A-8010 Graz, Austria
bDivision of Biochemical Engineering, Institut für Lebensmitteltechnologie der Universität für Bodenkultur Wien,
Muthgasse 18, A-1190 Vienna, Austria
Received 29 October 1999; accepted 18 November 1999
Abstract
5-Deoxy-5-fluoro-D-xylulose as well as a range of new 5,6-dimodified open-chain analogues of D-fructose,
namely the 5,6-diazido-5,6-dideoxy, 6-azido-5,6-dideoxy, 6-azido-5,6-dideoxy-5-fluoro, 5,6-dideoxy-5-fluoro,
5,6-dideoxy-6-fluoro and 5,6-dideoxy-5,6-difluoro derivatives, were synthesised employing glucose isomerase
catalysed isomerisation of the corresponding D-xylo- and D-glucofuranoses as a key step. New compounds as
well as some previously reported analogues such as 5-azido-5,6-dideoxy-6-fluoro-D-fructose were shown to be
excellent substrates of polyol dehydrogenase from Burkholderia cepacia DSM 50181 with Km values two orders
of magnitude smaller than the corresponding natural substrates. © 2000 Elsevier Science Ltd. All rights reserved.
1. Introduction
Polyol dehydrogenases are widespread in Nature and catalyse the reversible oxidation of a polyol into a
ketose. Many polyol dehydrogenases utilise NAD(H) as the redox co-enzyme, and therefore the reaction
of sorbitol dehydrogenase with D-sorbitol is:
D-sorbitol+NAD+zD-fructose+NADH+H+
NAD-dependent polyol dehydrogenases (PDHs) appear to cope with a number of different physiolo-
gical functions. For example, they are involved in mainstream carbohydrate catabolism in which energy
for growth and maintenance is generated,1 as well as in detoxification metabolism.2 Several important
details of enzyme/substrate interactions of PDHs are not well understood, and structural information at
high resolution is not available for this class of enzymes. We would like to have a better understanding
of how binding energy is utilised by PDHs to bring about catalytic efficiency, and related this to the
proposed roles of these enzymes in vivo. The use of substrate analogues in kinetic studies is instrumental
∗
Corresponding author. E-mail: stuetz@orgc.tu-graz.ac.at
0957-4166/00/$ - see front matter © 2000 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(99)00526-1
tetasy 3161

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to identify important enzyme/substrate interactions and to quantify the contributions of these interactions
to transition state stabilisation. Here, we report experiments in which open-chain derivatives of D-
fructose have been used to characterise the specificity of a bacterial PDH (from B. cepacia DSM 50181).
Generally, microbial PDHs are considered interesting biocatalysts in the stereospecific reduction of
carbonyl substrates.3
Very recently, we successfully employed 5,6-dimodified D-glucose derivatives, which are characterised
by a significantly increased amount of acyclic aldehyde tautomer in aqueous solution, as valuable tools
to probe the active sites as well as the substrate specificities of microbial aldose reductases.4 A similar
biochemical application was envisaged for 5,6-dimodified derivatives of D-fructose and D-xylulose as
open-chain substrate analogues of microbial polyol dehydrogenases.
Available methodology for the preparation of the desired 5,6-dimodified ketoses has been fairly
limited. An important approach is the aldolase catalysed addition of 2,3-dimodified glyceraldehyde
derivatives to dihydroxyacetone phosphate.5 Following pioneering work by Bock and co-workers,6 a
viable alternative to the aldolase based method was recently found in the glucose isomerase (EC 5.3.1.5)7
mediated conversion of 5,6-dimodified aldofuranoses into open-chain ketoses8 and other analogues of D-
fructose, L-sorbose9 as well as D-psicose and L-tagatose.10
2. Results and discussion
2.1. Syntheses
For the preparation of 5-modified D-xyluloses, 1,2-O-isopropylidene-D-xylofuranose 111 served as
the starting material (Scheme 1). Regioselective reaction with diethylaminosulfur trifluoride (DAST)
gave the corresponding known12 5-deoxyfluoro derivative 2 which was deprotected to yield 5-deoxy-5-
fluoro-D-xylose 3. The latter was isomerised employing the standard procedure to give 5-deoxyfluoro-
D-xylulose 4, a pentulose which was previously synthesised with the aid of yeast transketolase and
racemic 3-fluoro-2-hydroxypropanal.13 5-Azido-5-deoxy-D-xylulose 59a and 5-deoxy-D-xylulose 614
were obtained according to published approaches.
Scheme 1. Reagents and conditions: (a) DAST, CH2Cl2, −40°C, inverse addition; (b) IR 120, H2O/CH3CN, 50°C; (c) EC
5.3.1.5, MgSO4, H2O, 60°C
Based on the previously established and proven route,15 1,2-O-isopropylidene-α-D-glucofuranurono-
6,3-lactone16 was employed as the starting material for syntheses of 5,6-dimodified D-glucofuranoses.
From easily accessible 5-deoxy-1,2-O-isopropylidene-D-xylo-hexofuranurono-6,3-lactone,17 5-deoxy-
1,2-O-isopropylidene-α-D-xylohexofuranose 718 was prepared by sodium tetrahydridoborate reduction.
6-O-Tritylation and subsequent acetylation of O-3 were achieved in a simple one-pot procedure to give
fully protected intermediate 8. Chemoselective deprotection19 of O-6 yielded compound 9 which was
converted into the corresponding 6-triflate 10 (Scheme 2). For the preparation of the 5,6-dideoxy-6-
fluoro derivative 11, this was reacted with ‘dry tetrabutylammonium fluoride’20 in acetonitrile at ambient

P. Hadwiger et al. / Tetrahedron: Asymmetry 11 (2000) 607–620
609
temperature. For the synthesis of the corresponding 6-azido-5,6-dideoxy compound 12, triflate 10 was
treated with sodium azide in acetone.
Scheme 2. Reagents and conditions: (a) (i) TrCl, Py, 45°C, (ii) Ac2O; (b) BF3Et2O, MeOH, CH2Cl2; (c) Tf2O, Py, CH2Cl2,
−15°C
Likewise, 5-deoxy-5-fluoro-1,2-O-isopropylidene-α-D-glucofuranurono-6,3-lactone21 was employed
as an intermediate for compounds of the 5-deoxyfluoro series following essentially the same approach:
conventional reduction of the lactone moiety led to 5-deoxy-5-fluoro-1,2-O-isopropylidene-α-D-
glucofuranose 13.21 Compound 13 was regioselectively protected at O-6 with chlorotriphenylmethane
in pyridine followed by acetylation of O-3 in a one-pot procedure. Deprotection of O-6 in 14
led to the fluoroalcohol 15 which was transformed into the corresponding triflate 16. Its reaction
with dry tetrabutylammonium fluoride20 in acetonitrile at ambient temperature gave 5,6-dideoxy-
5,6-difluoroglucose derivative 17, whereas 6-azido-5,6-dideoxy-5-fluoro-1,2-O-isopropylidene-α-
D-glucofuranose 18 was formed with sodium azide in acetone. Reaction of intermediate 16 with
sodium iodide gave intermediate 19 which was further processed by catalytic hydrogenation to furnish
5,6-dideoxy-5-fluorosugar 20.
Conversely, the synthesis of 5,6-diazido-5,6-dideoxy-1,2-O-isopropylidene-α-D-glucofuranose 23
(Scheme 3) did not require the standard protection–deprotection sequence described but was readily
achieved from 5-azido-5-deoxy-1,2-O-isopropylidene-α-D-glucofuranose 21 which was synthesised
from 5-azido-5-deoxy-1,2-O-isopropylidene-α-D-glucofuranurono-6,3-lactone.22 Regioselective tosyla-
tion of O-6 followed by treatment with sodium azide in N,N-dimethylformamide (DMF) gave access to
the desired derivative 23. All attempts to employ the same approach with compound 7 invariably led to
the formation of the corresponding 3,6-anhydro derivatives.
Scheme 3. Reagents and conditions: (a) TsCl, Py; (b) NaN3, DMF, 45°C
5,6-Dideoxy-1,2-O-isopropylidene-α-D-xylo-hex-5-eno-furanose 409a as well as the corresponding
5,6-dideoxy derivative 24 were synthesised from suitable 3-O-protected 1,2-O-isopropylidene-α-D-
glucofuranose derivatives via Tipson–Cohen elimination of the corresponding 5,6-dimesylates.23
Acidic hydrolysis of the protected 5,6-dimodified aldofuranoses (Scheme 4) furnished the correspon-
ding free sugars 25–31 in good yields. All modified aldose derivatives were accepted as substrates by
immobilised glucose isomerase (Sweetzyme T) at 65°C and pH 7 and yielded the desired open-chain
ketoses 32–39 in isolated yields ranging between 22 and 63%. 5-Azido-5,6-dideoxy-6-fluoro-D-fructose
39 was synthesised by a similar route.24

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Scheme 4. Reagents and conditions: (a) IR 120, H2O/CH3CN, 50°C; (b) EC 5.3.1.5, MgSO4, H2O, 60°C
2.2. Biochemical studies
Open-chain ketoses were employed as substrates with B. cepacia. Data obtained from these experi-
ments are listed in Table 1.
Table 1
Kinetic parameters of polyol dehydrogenase from Burkholderia cepacia determined in 50 mM
potassium phosphate buffer, pH 7.5 and 25°C. The concentration of NADH was 200 µM and constant
at apparent saturation of the enzyme

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611
Steady state kinetic parameters were determined for the NADH-dependent reduction of compounds
32–40 catalysed by PDH. They are summarised in Table 1 and compared with the corresponding kinetic
parameters for the reduction of D-fructose. Preliminary results obtained reveal important interactions
between the enzyme or, presumably, the binary complex between the enzyme and NADH, and the
positions 5 and 6 of the substrates. They also indicate that the open-chain derivatives of D-fructose probed
are valuable substrate analogues for the evaluation of mechanistic aspects in the NADH-dependent
reduction of carbonyl groups catalysed by polyol dehydrogenases such as the PDH from B. cepacia.
Polar functionalities, for example azido and fluoro substituents, at C-5 of the ketose (compounds 34–37)
result in clearly superior substrate properties as compared with D-fructose as well as various open-chain
5-deoxy derivatives thereof, such as compounds 32, 33, 38 and the 5,6-eno analogue 40. A detailed
interpretation of the results regarding substrate recognition and catalysis by PDH will be presented
elsewhere.
3. Experimental
3.1. General methods
Melting points were recorded on a Tottoli apparatus and are uncorrected. Optical rotations were
measured on a Perkin–Elmer 341 with a path length of 10 cm. NMR spectra were recorded at 200 as well
as 300 MHz (1H), and at 50.29 and 75.47 MHz (13C). CDCl3 was employed for protected compounds
and D2O or CD3OD for free sugars. Chemical shifts are listed in δ employing residual, not deuterated,
solvent as the internal standard. TLC was performed on precoated aluminium sheets (E. Merck 5554).
TLC plates were stained with concd H2SO4 containing 5% vanillin. For column chromatography silica
gel 60 (E. Merck) was used. Mixtures of ethyl acetate:cyclohexane (1:10 to 3:1) were used for TLC and
column chromatography of protected compounds, ethyl acetate as well as ethyl acetate:MeOH mixtures
(10:1 to 4:1) were employed for TLC and chromatography of unprotected sugars. Saturated aqueous
bicarbonate for washing was freshly prepared.
3.2. PDH
The enzyme was isolated from crude cell extracts of B. cepacia DSM 50181, grown on medium
containing D-sorbitol as the main carbon source. The full purification procedure will be published
elsewhere. An enzyme preparation with a specific activity of approx. 40 units (µmol min−1) per mg
protein showed a single band in SDS–PAGE and in non-denaturing anionic PAGE. Staining for enzyme
activity with D-sorbitol as the substrate in non-denaturing gels unequivocally identified the protein band
as PDH. The preparation did not contain any detectable contamination by mannitol dehydrogenase.
Standard assays for PDH activity and mannitol dehydrogenase activity were carried out in 50 mM tris
buffer, pH 9.0, at 25°C using 200 mM D-sorbitol or D-mannitol as substrates, respectively, and 2 mM
NAD as co-enzyme. One unit refers to 1 µmol NADH produced per minute under these conditions.
3.3. Initial velocity studies
Measurements of the initial rate of carbonyl reduction were performed with a Beckman DU-650
spectrophotometer at 25°C by using NADH as the co-enzyme. The oxidation of co-enzyme upon carbonyl
reduction was monitored at 340 nm (1 to 5 min, rate of 0.05 to 0.1 DA·min−1). All rates were corrected

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P. Hadwiger et al. / Tetrahedron: Asymmetry 11 (2000) 607–620
for the appropriate blank readings, lacking either the substrate or the enzyme. The standard reaction
mixture had a total volume of 0.3 ml. It contained approx. 10 µg mL−1 PDH and a constant concentration
of 200 µM NADH, dissolved in 50 mM potassium phosphate, pH 7.5. The substrate was varied, typically
in 6 to 7 different concentration points, over a concentration range covering approximately 0.5 to 5 times
the Km.
3.4. Chemical procedures
3.4.1. General procedure for the introduction of heterosubstituents
To a solution of the OH-6 unprotected alcohol in dichloromethane containing 1.5 equivalents pyridine,
a 10% solution of 1.1 equivalents trifluoromethanesulfonic anhydride in CH2Cl2 was added dropwise
at −15°C. When TLC indicated the quantitative formation of a faster moving product, the solution was
diluted with CH2Cl2 and washed consecutively with 5% aq. HCl and satd aq. NaHCO3 and dried over
Na2SO4. After filtration and removal of the solvent under reduced pressure the residue was dissolved
in the appropriate solvent and the respective nucleophile (3 to 5 equivalents) was added (fluorosugars
were prepared with dried tetrabutylammonium fluoride in acetonitrile, azidosugars were synthesised with
sodium azide in acetone and for the introduction of iodine, sodium iodide in N,N-dimethylformamide was
employed). The reaction mixture was stirred at ambient temperature until TLC indicated quantitative
conversion of the triflate, after which it was diluted with dichloromethane and washed with water. After
drying (Na2SO4), filtration and evaporation of the solvents the residue was purified by chromatography.
3.4.2. General procedure for the one-pot protection of diols with chlorotriphenylmethane and acetic
anhydride
To a solution (20%) of the respective diol in pyridine, 1.5 equivalents chlorotriphenylmethane were
added and the solution was heated to 45°C until TLC indicated the quantitative conversion of the starting
material. The reaction mixture was allowed to reach ambient temperature when acetic anhydride was
added. Upon completion (TLC), the mixture was concentrated under reduced pressure. The residue
was partitioned between dichloromethane and 5% aq. HCl; the organic layer was washed with satd aq.
NaHCO3 and dried over Na2SO4. Filtration and evaporation of the solvent under reduced pressure gave
the crude product which was purified by chromatography.
3.4.3. General procedure for the cleavage of trityl ethers19
To a solution of the fully protected furanose in dichloromethane containing 5% methanol, boron
trifluouride etherate (1.1 equivalents) was added and the mixture was kept at room temperature until
TLC indicated the complete consumption of the starting material. The reaction mixture was diluted with
CH2Cl2 and washed with satd aq. NaHCO3. The organic layer was dried over Na2SO4, filtered and
concentrated under reduced pressure. The residue was purified by chromatography.
3.4.4. General procedure for the removal of acetate and isopropylidene protecting groups
An aqueous acetonitrile solution (CH3CN:H2O 1:1 v/v) containing the respective 3-O-acetyl-1,2-O-
isopropylidene derivative was stirred with Amberlite IR-120 [H+] ion-exchange resin, which had been
washed with distilled water before use, at 50°C before use. When TLC indicated the completion of the
reaction, the resin was removed by filtration and the solution was concentrated under reduced pressure.
The free aldofuranose was purified by chromatography.

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613
3.4.5. General procedure for isomerisation reactions with immobilised glucose isomerase
To a 5% solution of the respective free sugar in distilled water, a few drops of a 1% aqueous solution
of MgSO4 and 4 equiv. (w/w) of immobilised glucose isomerase (Sweetzyme T) were added and the
mixture was spun on a rotary evaporator or shaken at 60°C for 3 to 8 h. After the appropriate reaction
time, the solids were filtered off, the solution was concentrated under reduced pressure and the residue
was chromatographed on silica gel. Alternatively, in case of similar polarities of product and starting
material, the aqueous solution was treated with bromine in the presence of barium carbonate to oxidise the
remaining aldose to the corresponding lactone to allow easier separation. Nitrogen was bubbled through
the brown reaction mixture, the solids were removed by filtration, the solution was concentrated under
reduced pressure and the residue subjected to chromatography. The aldonolactone can be recycled by
conventional reduction to the free aldose.25
3.5. 5-Deoxy-5-fluoro-1,2-O-isopropylidene-α-D-xylofuranose 2
Diethylaminosulfur trifluoride (DAST, 10.2 g, 63.1 mmol, 4 equiv.) was dissolved in 100 mL CH2Cl2,
which had been rinsed over basic aluminium oxide (Aldrich, 150 mesh),26 and cooled to −40°C. Then,
1,2-O-isopropylidene-α-D-xylofuranose (1, 3.0 g)11 dissolved in 20 mL dichloromethane was added
dropwise and the reaction mixture was left overnight at 4°C. After cooling to −50°C the reaction
was quenched by adding 4 mL methanol and stirring for 20 min. The mixture was diluted with satd
aq. NaHCO3 and extracted with dichloromethane. The organic layer was dried (Na2SO4), filtered and
concentrated under reduced pressure. The residue was purified by chromatography to yield 1.02 g (34%)
20
20
of compound 2. Mp: 82–84°C [lit.12 mp: 86°C]; [α]D −11.4 (c 2.25, CH2Cl2) [lit.12 [α]D −20.6 (c
1, CHCl3)]; 1H NMR (200 MHz, CDCl3): δ 5.98 (d, 1H, J1,2 3.6 Hz, H-1), 4.75 (ddd, 1H, J5,F 46.8 Hz,
J5,5 10.0 Hz, H-5), 4.60 (ddd, 1H, H-50), 4.53 (dd, 1H, J2,F 1.5 Hz, H-2),27 4.41 (dddd, 1H, J4,5 5.2 Hz,
0
J4,5 5.1 Hz, J4,F 16.6 Hz, H-4), 4.33 (m, 1H, J3,4 2.8 Hz, H-3); 13C NMR: δ 112.1 (4°C, Isp), 105.0
0
(C-1), 85.4 (C-2), 81.3 (J5,F 166 Hz, C-5), 78.4 (J4,F 22.0 Hz, C-4), 75.2 (J3,F 4.7 Hz, C-3), 26.8, 26.2
(2×CH3, Isp).
3.6. 5-Deoxy-5-fluoro-D-xylofuranose 3
Compound 2 (980 mg, 5.10 mmol) was hydrolysed according to the respective general procedure and
gave xylofuranose 3 (668 mg, 86%). [α]D20 +36.4 (c 1.55, MeOH) [lit.12 [α]20D +52.7 (c 1.7, H2O)]; 1H
NMR (300 MHz, D2O): δ 5.61 (s, 1H, H-1α), 5.42 (s, 1H, H-1β), α:β-ratio: 1.2:1; 13C NMR: δ 102.5,
96.5 (C-1α/C-1β), 84.5, 83.8 (J5,F 163.6 Hz, J5,F 163.6 Hz, C-5α/C-5β), 81.2 (C-2α/C-2β), 80.5 (J4,F
19.5 Hz, C-4α/C-4β), 77.6 (J4,F 17.6 Hz, C-4α/C-4β), 76.8 (C-2α/C-2β), 75.7 (J3,F 6.3 Hz, C-3α/C-3β),
75.4 (J3,F 4.5 Hz, C-3α/C-3β).
3.7. 5-Deoxy-5-fluoro-D-threo-pentulose 4 (5-deoxy-5-fluoro-D-xylulose)
The general procedure for the isomerisation was applied. The ketose 4 is less polar than the starting
material and the aldose 3 could be recycled without derivatisation by column chromatography. Deoxy-
20
fluoroaldose 3 (543 mg, 3.57 mmol) yielded 261 mg (48%) of desired ketose 4. [α]D −36.7 (c 2.25,
20
MeOH); [lit.13 [α]D −2.4 (c 0.3, D2O)]; 1H NMR spectra data were identical with values given in Ref.
13; 13C NMR: δ 213.2 (C-2), 84.7 (J5,F 165.9 Hz, C-5), 75.8 (J3,F 5.1 Hz, C-3), 71.0 (J4,F 20.6 Hz, C-4),
67.0 (C-1).

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3.8. 3-O-Acetyl-5-deoxy-1,2-O-isopropylidene-6-O-triphenylmethyl-α-D-xylo-hexofuranose 8
Compound 7 (3.57 g, 17.5 mmol) was processed according to the general procedure for the one-pot
20
protection sequence and led to compound 8 (8.25 g, 99%) as a slightly yellow foam. [α]D −17.1 (c
4.6, CH2Cl2); 1H NMR (200 MHz, CDCl3): δ 7.47–7.19 (m, 15H, Ar), 5.89 (d, 1H, J1,2 3.9 Hz, H-1),
0
5.08 (d, 1H, J3,4 2.7 Hz, H-3), 4.58 (m, 1H, J4,5 6.2 Hz, H-4), 4.51 (d, 1H, H-2), 3.21 (m, 2H, J6,6 15.9
Hz, H-6, H-60), 2.06 (s, 3H, CH3, Ac), 1.91 (m, 2H, H-5, H-50), 1.53 (s, 3H, CH3, Isp), 1.32 (s, 3H, CH3,
Isp); 13C NMR: δ 169.9 (CO, Ac), 144.2, 128.7, 127.8, 127.0 (Ar), 111.8 (4°C, Isp), 104.4 (C-1), 86.6
(4°C, Tr), 83.7, 77.4, 76.3 (C-2/C-3/C-4), 60.4 (C-6), 28.7 (C-5), 26.6, 26.3 (2×CH3, Isp), 20.8 (CH3,
Ac).
3.9. 3-O-Acetyl-5-deoxy-1,2-O-isopropylidene-α-D-xylo-hexofuranose 9
The general procedure for the removal of the trityl ether group was applied. Compound 8 (2.15 g, 4.40
mmol) was deprotected and afforded 9 (876 mg, 81%) as a colourless oil. [α] +4.3 (c 0.85, CH2Cl2);
1H NMR (200 MHz, CDCl3): δ 5.89 (d, 1H, J1,2 3.8 Hz, H-1), 5.16 (d, 1H, J3,4 2.8 Hz, H-3), 4.50 (d,
1H, H-2), 4.42 (ddd, 1H, J4,5 4.8 Hz, J4,5’ 8.2 Hz, H-4), 3.76 (m, 2H, H-6, H-60), 2.25 (s, 1H, OH), 2.09
(s, 3H, CH3, Ac), 1.84 (m, 2H, H-5, H-50), 1.51 (s, 3H, CH3, Isp), 1.30 (s, 3H, CH3, Isp); 13C NMR: δ
170.0 (CO, Ac), 112.0 (4°C, Isp), 104.5 (C-1), 83.5, 77.6, 77.4 (C-2/C-3/C-4), 60.2 (C-6), 30.7 (C-5),
26.6, 26.2 (2×CH3, Isp), 20.8 (CH3, Ac).
3.10. 3-O-Acetyl-5,6-dideoxy-6-fluoro-1,2-O-isopropylidene-α-D-xylo-hexofuranose 11
Compound 9 (876 mg, 3.56 mmol) was triflated to furnish intermediate 10. The subsequent displace-
ment of the leaving group with dry TBAF according to the respective general procedure afforded 627 mg
20
(71%) 23 as a colourless oil. [α]D −1.6 (c 0.7, CH2Cl2); 1H NMR (200 MHz, CDCl3): δ 5.89 (dd, 1H,
J1,2 3.8 Hz, H-1), 5.16 (d, 1H, J3,4 2.8 Hz, H-3), 4.7–4.4 (m, 3H, J6,F 46.7 Hz, H-4, H-6, H-60), 4.52 (d,
1H, H-2), 4.48 (ddd, 1H, J6 ,F 47.4 Hz, H-60), 2.09 (s, 3H, CH3, Ac), 2.05–1.88 (m, 2H, H-5, H-50), 1.51
0
(s, 3H, CH3, Isp), 1.31 (s, 3H, CH3, Isp); 13C NMR: δ 169.9 (CO, Ac), 112.1 (4°C, Isp), 104.6 (C-1),
83.8 (C-2), 81.0 (J6,F 165.5 Hz, C-6), 77.2 (C-3), 75.6 (J4,F 4.5 Hz, C-4), 29.5 (J5,F 20.8 Hz, C-5), 26.7,
26.3 (2×CH3, Isp), 20.8 (CH3, Ac).
3.11. 6-Azido-3-O-acetyl-5,6-dideoxy-1,2-O-isopropylidene-α-D-xylo-hexofuranose 12
Intermediate 10 was synthesised from 9 (1.15 g, 4.67 mmol) according to the respective general
procedure. Nucleophilic substitution with sodium azide led to the desired compound 12 in 79% yield
20
1
(998 mg). Compound 12 was a colourless oil. [α]D −3.7 (c 1.25, CH2Cl2); H NMR (200 MHz,
CDCl3): δ 5.89 (d, 1H, J1,2 3.8 Hz, H-1), 5.16 (d, 1H, J3,4 2.9 Hz, H-3), 4.52 (d, 1H, H-2), 4.34 (ddd,
1H, J4,5 5.1 Hz, J4,5 8.2 Hz, H-4), 3.44 (m, 2H, J6,6 9.5 Hz, H-6, H-60), 2.11 (s, 3H, CH3, Ac), 1.84 (m,
2H, H-5, H-50), 1.51 (s, 3H, CH3, Isp), 1.30 (s, 3H, CH3, Isp); 13C NMR: δ 169.9 (CO, Ac), 112.1 (4°C,
Isp), 104.4 (C-1), 83.6, 77.0, 76.4 (C-2/C-3/C-4), 48.5 (C-6), 27.9 (C-5), 26.6, 26.2 (2×CH3, Isp), 20.8
(CH3, Ac).
0
0

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615
3.12. 3-O-Acetyl-5-deoxy-5-fluoro-1,2-O-isopropylidene-6-O-triphenylmethyl-α-D-glucofuranose 14
5-Deoxy-5-fluoro-1,2-O-isopropylidene-α-D-glucofuranose 821 (1.85 g, 8.32 mmol) was reacted ac-
cording to the general one-pot protection sequence to yield 3.39 g (80.0%) 14 as a faintly yellow foam.
20
[α]D −16.7 (c 2.2, CH2Cl2); 1H NMR (200 MHz, CDCl3): δ 7.52–7.24 (15H, Ar), 5.86 (dd, 1H, J1,2
0
3.6 Hz, J1,F 1.7 Hz, H-1), 5.36 (d, 1H, J3,4 2.8 Hz, H-3), 4.78 (dddd, 1H, J5,6 2.8 Hz, J5,6 4.5 Hz, J5,F
0
46.4 Hz, H-5), 4.70–4.54 (m, 1H, J4,5 8.6 Hz, H-4), 4.53 (d, 1H, H-2), 3.53 (ddd, 1H, J6,6 12.7 Hz, J6,F
29.2 Hz, H-6), 3.39 (ddd, 1H, H-60), 1.47 (s, 3H, CH3, Isp), 1.30 (s, 3H, CH3, Isp), 2.09 (s, 3H, CH3,
Ac), 1.52 (s, 3H, CH3, Isp), 1.50 (s, 3H, CH3, Isp); 13C NMR: δ 169.6 (CO, Ac), 143.8, 128.8, 128.2,
127.9, 127.3, 127.1 (Ar), 112.5 (4°C, Isp), 105.1 (C-1), 88.8 (J5,F 172.7 Hz, C-5), 86.7 (4°C, Tr), 83.2
(C-2), 76.0 (J4,F 30.7 Hz, C-4), 75.8 (C-3), 63.7 (J6,F 18.8 Hz, C-6), 26.9, 26.4 (2×CH3, Isp), 26.7, 26.3
(2×CH3, Isp), 20.8 (CH3, Ac).
3.13. 3-O-Acetyl-5-deoxy-5-fluoro-1,2-O-isopropylidene-α-D-glucofuranose 15
Compound 14 (1.90 g, 3.75 mmol) was deprotected according to the respective general procedure and
20
1
furnished 15 as a white solid (855 mg, 86%). Mp: 78–79°C; [α]D −30.1 (c 0.4, CH2Cl2); H NMR
(200 MHz, CDCl3): δ 5.91 (dd, 1H, J1,2 3.6 Hz, J1,F 1.8 Hz, H-1), 5.35 (d, 1H, J3,4 3.0 Hz, H-3), 4.70
(dddd, 1H, J5,6 2.6 Hz, J5,6 4.9 Hz, J5,F 46.9 Hz, H-5), 4.54 (d, 1H, H-2), 4.46 (ddd, 1H, J4,5 8.7 Hz, J4,F
0
5.8 Hz, H-4), 4.01 (ddd, 1H, J6,6 13.0 Hz, J6,F 25.1 Hz, H-6), 3.88 (ddd, 1H, J6 ,F 27.8 Hz, H-60), 2.15
(s, 3H, CH3, Ac), 1.53 (s, 3H, CH3, Isp), 1.36 (s, 3H, CH3, Isp); 13C NMR: δ 169.6 (CO, Ac), 112.8
(4°C, Isp), 105.2 (C-1), 89.7 (J5,F 170.0 Hz, C-5), 83.4 (C-2), 76.4 (J4,F 31.2 Hz, C-4), 75.9 (C-3), 63.0
(J6,F 20.5 Hz, C-6), 26.9, 26.4 (2×CH3, Isp), 20.9 (CH3, Ac).
0
0
3.14. 3-O-Acetyl-5,6-dideoxy-5,6-difluoro-1,2-O-isopropylidene-α-D-glucofuranose 17
The general procedure for the introduction of a fluorine atom was applied. Compound 15 (1.02 g, 3.86
20
1
mmol) led to 793 mg (77%) of the dideoxydifluoro derivative 17. [α]D −25.3 (c 2.05, CH2Cl2); H
NMR (200 MHz, CDCl3): δ 5.89 (dd, 1H, J1,2 3.6 Hz, J1,F 1.8 Hz, H-1), 5.34 (d, 1H, J3,4 2.8 Hz, H-3),
5.05–4.56 (m, 3H, H-5, H-6, H-60), 4.54 (d, 1H, H-2), 4.44 (m, 1H, H-4), 2.11 (s, 3H, CH3, Ac), 1.51 (s,
3H, CH3, Isp), 1.31 (s, 3H, CH3, Isp); 13C NMR: δ 169.3 (CO, Ac), 112.8 (4°C, Isp), 105.2 (C-1), 88.0
(J5,F-5 173.9 Hz, J5,F-6 18.8 Hz, C-5), 83.2 (C-2), 82.6 (J6,F-6 174.3 Hz, J6,F-5 19.5 Hz, C-6), 75.4 (C-3),
75.0 (J4,F-5 30.7 Hz, J4,F-6 7.7 Hz, C-4), 26.8, 26.2 (2×CH3, Isp), 20.8 (CH3, Ac).
3.15. 3-O-Acetyl-6-azido-5,6-dideoxy-5-fluoro-1,2-O-isopropylidene-α-D-glucofuranose 18
The respective general procedure applied to 15 (774 mg, 2.93 mmol) led to intermediate 16 which was
immediately used for the displacement reaction with NaN3 in acetone. 772 mg (91%) of compound 18
20
was obtained as colourless oil. [α]D −37.8 (c 2.2, CH2Cl2); 1H NMR (200 MHz, CDCl3): δ 5.87 (dd,
0
1H, J1,2 3.6 Hz, J1,F 1.8 Hz, H-1), 5.33 (d, 1H, J3,4 3.0 Hz, H-3), 4.76 (dddd, 1H, J5,6 2.9 Hz, J5,6 5.6
Hz, J5,F 46.7 Hz, H-5), 4.53 (d, 1H, H-2), 4.39 (ddd, 1H, J4,5 8.5 Hz, J4,F 4.9 Hz, H-4), 3.68 (ddd, 1H,
J6,F 27.0 Hz, J6,6 12.6 Hz, H-6), 3.55 (ddd, 1H, H-60), 2.11 (s, 3H, CH3, Ac), 1.52 (s, 3H, CH3, Isp),
0
1.30 (s, 3H, CH3, Isp); 13C NMR: δ 169.3 (CO, Ac), 112.8 (4°C, Isp), 105.1 (C-1), 88.3 (J5,F 173.6 Hz,
C-5), 83.3 (C-2), 76.6 (J4,F 30.3 Hz, C-4), 75.5 (C-3), 52.4 (J6,F 19.0 Hz, C-6), 26.8, 26.2 (2×CH3, Isp),
20.7 (CH3, Ac).

616
P. Hadwiger et al. / Tetrahedron: Asymmetry 11 (2000) 607–620
3.16. 3-O-Acetyl-5,6-dideoxy-5-fluoro-6-iodo-1,2-O-isopropylidene-α-D-glucofuranose 19
The same procedure as for compound 18 applied to 15 (940 mg, 3.56 mmol) and subsequent treatment
20
with sodium iodide in DMF led to 19 (1.16 g, 87%) as a white solid, mp: 62–63°C; [α]D −24.7 (c 1.45,
1
CH2Cl2); H NMR (200 MHz, CDCl3): δ 5.91 (bs, 1H, H-1), 5.31 (d, 1H, J3,4 2.5 Hz, H-3), 4.64 (m,
0
1H, H-4), 4.52 (d, 1H, J1,2 3.5 Hz, H-2), 4.48 (dddd, 1H, J5,6 2.7 Hz, J5,6 5.3 Hz, J5,F 47 Hz, H-5), 3.59
(ddd, 1H, J6,6 11.6 Hz, J6,F 26.0 Hz, H-6), 3.39 (ddd, 1H, J6 ,F 24.5 Hz, H-60), 2.15 (s, 3H, CH3, Ac),
1.53 (s, 3H, CH3, Isp), 1.36 (s, 3H, CH3, Isp), 2.10 (s, 3H, CH3, Ac), 1.51 (s, 3H, CH3, Isp), 1.30 (s, 3H,
CH3, Isp); 13C NMR: δ 169.3 (CO, Ac), 112.9 (4°C, Isp), 105.0 (C-1), 87.4 (J5,F 174.8 Hz, C-5), 83.3
(C-2), 79.2 (J4,F 30.7 Hz, C-4), 75.4 (C-3), 26.9, 26.4 (2×CH3, Isp), 20.8 (CH3, Ac), 5.1 (J6,F 21.0 Hz,
C-6).
0
0
3.17. 3-O-Acetyl-5,6-dideoxy-5-fluoro-1,2-O-isopropylidene-α-D-glucofuranose 20
50 mL methanol containing 19 (1.03 g, 2.76 mmol), triethylamine (0.33 g, 3.31 mmol, 1.2 equiv.)
and Raney-Ni was stirred under an atmosphere of hydrogen. When TLC indicated quantitative reaction
the catalyst was removed by filtration and the solution concentrated under reduced pressure. The
residue was dissolved in dichloromethane and consecutively washed with 5% aq. HCl and satd aq.
NaHCO3. The organic layer was dried (Na2SO4), filtered and evaporated and finally purified by column
chromatography. Compound 20 was a white solid and was obtained in 87% (594 mg) yield. Mp 64–66°C;
20
[α]D −16.4 (c 1.55, CH2Cl2); 1H NMR (200 MHz, CDCl3): δ 5.88 (dd, 1H, J1,2 3.8 Hz, J1,F 1.8 Hz,
H-1), 5.31 (d, 1H, J3,4 3.0 Hz, H-3), 4.76 (ddq, 1H, J5,6 6.3 Hz, J5,F 47.0 Hz, H-5), 4.50 (d, 1H, H-2),
4.15 (ddd, 1H, J4,5 8.1 Hz, J4,F 6.2 Hz, H-4), 2.09 (s, 3H, CH3, Ac), 1.46 (dd, 3H, J6,F 25.4 Hz, H-6), 1.51
(s, 3H, CH3, Isp), 1.29 (s, 3H, CH3, Isp); 13C NMR: δ 169.5 (CO, Ac), 112.4 (4°C, Isp), 104.9 (C-1),
86.3 (J5,F 165.3 Hz, C-5), 83.5 (C-2), 80.6 (J4,F 30.5 Hz, C-4), 75.4 (C-3), 26.7, 26.2 (2×CH3, Isp), 20.8
(CH3, Ac), 18.7 (J6,F 21.2 Hz, C-6).
3.18. 5-Azido-5-deoxy-1,2-O-isopropylidene-6-O-tosyl-α-D-glucofuranose 22
5-Azido-5-deoxy-1,2-O-isopropylidene-α-D-glucofuranose (21,22 1.12 g, 4.57 mmol) dissolved in 20
mL pyridine was treated with 1.31 g (6.85 mmol, 1.5 equiv.) p-toluenesulfonyl chloride at 0°C. Stirring
was continued at room temperature until TLC indicated quantitative consumption of the starting material.
Methanol (5 mL) was added and the mixture was concentrated under reduced pressure. The residue
was partitioned between dichloromethane and 5% aq. HCl; the organic layer was washed with satd aq.
NaHCO3 and dried over Na2SO4. Filtration and evaporation of the solvent gave the crude product 22
20
which was purified by chromatography to yield 1.66 g (91%). Compound 22 was a colourless oil. [α]D
−24.8 (c 1.8, CH2Cl2); 1H NMR (200 MHz, CDCl3): δ 5.87 (d, 1H, J1,2 3.5 Hz, H-1), 4.48 (d, 1H, H-2),
4.41 (m, 1H, H-4), 4.29 (bs, 1H, H-3), 4.13–3.88 (m, 3H, H-5, H-6, H-60) 2.45 (s, 3H, CH3, Ts), 2.25
(d, 1H, J3,OH-3 4.9 Hz, OH), 1.45 (s, 3H, CH3, Isp), 1.29 (s, 3H, CH3, Isp); 13C NMR: δ 145.2, 132.5,
130.0, 128.1 (Ar, Ts), 112.3 (4°C, Isp), 105.1 (C-1), 85.0, 78.5, 74.6 (C-2/C-3/C-4), 70.2 (C-6), 58.4
(C-5), 26.8, 26.2 (2×CH3, Isp), 21.7 (CH3, Ts).
3.19. 5,6-Diazido-5,6-dideoxy-1,2-O-isopropylidene-α-D-glucofuranose 23
A suspension of 22 (445 mg, 1.11 mmol) and sodium azide (361 mg, 5.55 mmol, 5 equiv.) in 20 mL
DMF was stirred at 45°C. After complete reaction (judged by TLC) most of the solvent was evaporated

P. Hadwiger et al. / Tetrahedron: Asymmetry 11 (2000) 607–620
617
under reduced pressure and the residue was partitioned between CH2Cl2 and water. The organic layer was
dried (Na2SO4), filtered and evaporated. Chromatography of the crude product afforded 266 mg (88%)
20
1
of compound 23 as a colourless syrup. [α]D −64.2 (c 4.0, CHCl3); H NMR (200 MHz, CDCl3): δ
5.90 (d, 1H, J1,2 3.5 Hz, H-1), 4.50 (d, 1H, H-2), 4.32 (d, 1H, J3,4 2.7 Hz, H-3), 4.04 (dd, 1H, J4,5 9.2
0
0
Hz, H-4), 3.89 (ddd, 1H, J5,6 2.9 Hz, J5,6 7.1 Hz, H-5), 3.67 (dd, 1H, J6,6 12.8 Hz, H-6), 3.47 (dd, 1H,
H-60), 2.61 (s, 1H, OH), 1.47 (s, 3H, CH3, Isp), 1.30 (s, 3H, CH3, Isp); 13C NMR: δ 112.3 (4°C, Isp),
105.0 (C-1), 85.2, 79.2, 74.5 (C-2/C-3/C-4), 59.5 (C-5), 52.8 (C-6), 26.8, 26.2 (2×CH3, Isp).
3.20. 5,6-Dideoxy-6-fluoro-D-xylo-hexofuranose 25
Hydrolysis of 11 (510 mg, 2.05 mmol) according to the general procedure afforded 280 mg (82%) of
20
compound 25 as a colourless oil. [α]D +21.8 (c 2.35, MeOH); 1H NMR (200 MHz, D2O): δ 5.39 (d,
1H, J1,2 4.2 Hz, H-1α), 5.13 (s, 1H, H-1β), α:β-ratio: 1:1; 13C NMR: δ 102.8, 96.7 (C-1α/C-1β), 83.5,
83.3 (J6,F 159.0 Hz, J6,F 158.5 Hz, C-6α/C-6β), 81.7 (C-2α/C-2β), 79.6 (J4,F 4.3 Hz, C-4α/C-4β), 77.1
(2 signals, C-2α/C-2β/C-3α/C-3β), 76.9 (J4,F 4.3 Hz, C-4α/C-4β), 76.4 (C-3α/C-3β), 31.1, 30.5 (J5,F
19.5 Hz, C-5α/C-5β).
3.21. 6-Azido-5,6-dideoxy-D-xylo-hexofuranose 26
20
Deprotection of 12 (820 mg, 3.02 mmol) led to desired aldose 26 (499 mg, 87%). [α]D +14.4 (c
1
4.25, MeOH); H NMR (200 MHz, CD3OD): δ 5.34 (d, 1H, J1,2 4.0 Hz, H-1α), 5.05 (s, 1H, H-1β),
α:β-ratio: 1:1; 13C NMR: δ 104.1, 97.5 (C-1α/C-1β), 82.7, 80.3, 78.5, 78.0, 77.8, 77.7 (C-2α/C-2β/C-
3α/C-3β/C-4α/C-4β), 49.7, 49.5 (C-6α/C-6β), 30.7, 29.9 (C-5α/C-5β).
3.22. 5,6-Dideoxy-5,6-difluoro-D-glucofuranose 27
Removal of the protecting groups in 17 (785 mg, 2.95 mmol) yielded compound 27 (451 mg, 83%)
20
1
as a white solid. [α]D −5.3 (c 1.4, MeOH); H NMR (200 MHz, D2O): δ 5.46 (d, 1H, J1,2 3.9 Hz,
H-1α), 5.42 (d, 1H, J1,2 2.7 Hz, H-1β), α:β-ratio: 1:1; 13C NMR: δ 102.4 (C-1β), 96.8 (C-1α), 89.5
(J5-α,F-5=J5-β,F-5170.0 Hz, J5α,F-6=J5β,F-6 18.0 Hz, C-5α/C-5β), 83.4, 83.1 (J6α,F-6=J6β,F-6 167.6 Hz, J6F-5
19.3/19.2 Hz, C-6α/C-6β), 80.1, 75.6 (C-2α/C-2β), 77.9, 75.1 (J4,F-5 29.5/28.6 Hz, J4,F-6 7.2/6.9 Hz, C-
4α/C-4β), 74.8 (J3,F-5 1.6 Hz, C-3α/C-3β), 74.4 (C-3α/C-3β).
3.23. 6-Azido-5,6-dideoxy-5-fluoro-D-glucofuranose 28
Acidic hydrolysis of the protecting groups in 18 (687 mg, 2.37 mmol) according to the respective
20
1
general procedure led to 28 (451 mg, 92%) as a colourless oil. [α]D +6.4 (c 2.0, MeOH); H NMR
(200 MHz, D2O): δ 5.44 (d, 1H, J1,2 3.8 Hz, H-1α), 5.22 (d, 1H, J1,2 2.7 Hz, H-1β), α:β-ratio: 1:1; 13
C
NMR: δ 102.3, 96.8 (C-1α/C-1β), 90.0, 88.8 (J5,F 170.2 Hz, C-5α+C-5β), 80.3 (C-2α/C-2β), 79.7 (J4,F
28.8 Hz, C-4α/C-4β), 76.3 (J4,F 28.0 Hz, C-4α/C-4β), 75.8 (C-2α/C-2β), 74.8 (J3,F 2.0 Hz, C-3α/C-3β),
74.5 (C-3α/C-3β), 52.1 (J6,F 15.5 Hz, C-6α/C-6β), 51.7 (J6,F 15.9 Hz, C-6α/C-6β).
3.24. 5,6-Dideoxy-5-fluoro-D-glucofuranose 29
The general deprotection procedure was applied to compound 20 (550 mg, 2.21 mmol) and 29 was
20
1
obtained in 86% yield. [α]D −6.7 (c 3.25, MeOH); H NMR (200 MHz, D2O): δ 5.44 (d, 1H, J1,2

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P. Hadwiger et al. / Tetrahedron: Asymmetry 11 (2000) 607–620
4.0 Hz, H-1α), 5.20 (bs, 1H, H-1β), α:β-ratio: 1.2:1; 13C NMR: δ 102.0, 96.2 (C-1α/C-1β), 89.0, 88.8
(J5α,F=J5β,F 162.0 Hz, C-5α/C-5β), 82.9 (J4,F 28.1 Hz, C-4α/C-4β), 80.3 (C-2α/C-2β), 79.7 (J4,F 26.4
Hz, C-4α/C-4β), 75.8 (C-2α/C-2β), 74.8 (J3,F 3.3 Hz, C-3α/C-3β), 74.4 (J3,F 2.1 Hz, C-3α/C-3β), 17.5
(J6,F 21.1 Hz, C-6α/C-6β), 16.8 (J6,F 21.5 Hz, C-6α/C-6β).
3.25. 5,6-Diazido-5,6-dideoxy-D-glucofuranose 30
Compound 23 (262 mg, 0.969 mmol) was deprotected according to the respective general procedure
and furnished 30 (217 mg, 97%) as a colourless oil. [α]20 −80.3 (c 2.5, MeOH); 1H NMR (200 MHz,
D
CD3OD3): δ 5.41 (d, 1H, J1,2 3.7 Hz, H-1α), 5.10 (s, 1H, H-1β), α:β-ratio: 1:1.2; 13C NMR: δ 104.7,
98.8 (C-1α/C-1β), 82.2, 82.1 (C-2α/C-2β), 79.2, 78.0, 77.1, 76.6 (C-3α/C-3β/C-4α/C-4β), 62.5, 61.9
(C-5α/C-5β), 54.5, 54.3 (C-6α/C-6β).
3.26. 5,6-Dideoxy-D-xylo-hexofuranose 31
Hydrolysis of the isopropylidene group in 2423 (192 mg, 1.02 mmol) according to the general
20
procedure gave 126 mg (83%) of compound 31 as a colourless oil. [α]D −0.5 (c 2.65, MeOH); [lit.28
20
1
[α]D +2 (c 0.9, EtOH)]; H NMR (300 MHz, CD3OD): δ 5.37 (d, 1H, J1,2 4.1 Hz, H-1α), 5.05 (s,
1H, H-1β), α:β-ratio: ≈1:1; 13C NMR: δ 104.0, 97.3 (C-1α/C-1β), 84.9, 82.6, 81.8, 78.4, 77.6, 76.9
(C-2α/C-2β/C-3α/C-3β/C-4α/C-4β), 23.8, 23.0 (C-5α/C-5β), 10.8, 10.6 (C-6α/C-6β).
3.27. 5,6-Dideoxy-6-fluoro-D-threo-hex-2-ulose 32
Following the respective general procedure 25 (212 mg, 1.28 mmol) was isomerised yielding 32 (82
20
mg, 39%) as a colourless syrup. [α]D −11.0 (c 2.9, MeOH); 1H NMR (200 MHz, D2O): δ 4.73–4.43
(m, 2H, J6 ,F 46.9 Hz, H-6, H-60), 4.59 (d, 1H, J1,1 19.5 Hz, H-1), 4.42 (d, 1H, H-10), 4.30 (d, 1H, J3,4
0
0
0
0
2.2 Hz, H-3) 4.17 (ddd, 1H, J4,5 5.0 Hz, J4,5 7.1 Hz, H-4), 2.02–1.8 (m, 2H, J5,F 28.4, J5 ,F 28.2 Hz,
H-5, H-50); 13C NMR: δ 212.8 (C-2), 81.8 (J6,F 158.9 Hz, C-6), 77.7 (C-3), 68.3 (J4,F 4.0 Hz, C-4), 66.1
(C-1), 33.2 (J5,F 19.2 Hz, C-5). Anal. calcd for C6H11O4F: C, 43.37; H, 6.67; found: C, 43.15; H, 6.90.
3.28. 6-Azido-5,6-dideoxy-D-threo-hex-2-ulose 33
Enzymatic isomerisation according to the respective general procedure of 26 (183 mg, 0.967 mmol)
20
gave 66 mg (36%) of the open-chain ketose 33 as a colourless syrup. [α]D +19.3 (c 1.25, MeOH);
1H NMR (200 MHz, CD3OD): δ 4.56 (d, 1H, J1,1 19.2 Hz, H-1), 4.43 (d, 1H, H-10), 4.14 (d, 1H, J3,4
0
2.4 Hz, H-3) 4.05 (ddd, 1H, J4,5 5.1 Hz, J4,5 8.0 Hz, H-4), 3.45 (m, 2H, H-6, H-60), 1.83 (m, 2H, H-5,
0
H-50); 13C NMR: δ 213.4 (C-2), 79.5, 70.6 (C-3/C-4), 67.9 (C-1), 49.3 (C-6), 33.5 (C-5). Anal. calcd for
C6H11O4N3: C, 38.10; H, 5.86; found: C, 38.01; H, 5.97.
3.29. 5,6-Dideoxy-5,6-difluor-D-fructose 34
The general procedure for the enzymatic isomerisation was applied. Compound 27 (340 mg, 1.85
20
1
mmol) afforded 173 mg (51%) of syrupy compound 34. [α]D −28.0 (c 3.1, MeOH); H NMR (200
MHz, D2O): δ 5.0–4.5 (m, 4H, H-3, H-5, H-6, H-60), 4.65 (d, 1H, J1,1 19.8 Hz, H-1), 4.52 (d, 1H, H-10),
0
4.29 (m, 1H, H-4); 13C NMR: δ 212.9 (C-2), 89.9 (J5,F-5 174.8 Hz, J5,F-6 17.8 Hz, C-5), 82.3 (J6,F-6 168.3

P. Hadwiger et al. / Tetrahedron: Asymmetry 11 (2000) 607–620
619
Hz, J6,F-5 19.5 Hz, C-6), 74.6 (C-3), 67.9 (J4,F-5 26.6 Hz, J4,F-6 7.1 Hz, C-4), 66.2 (C-1). Anal. calcd for
C6H10O4F2: C, 39.14; H, 5.47; found: C, 39.00; H, 5.61.
3.30. 6-Azido-5,6-didesoxy-5-fluor-D-fructose 35
Application of the respective general procedure to starting material 28 (346 mg, 1.67 mmol) afforded
186 mg (54%) of desired fructose derivative 35. [α]D20 +9.1 (c 4.4, MeOH); 1H NMR (200 MHz, D2O):
0
δ 4.76 (m, 1H, J5,F 46.3 Hz, J5,6 2.0 Hz, J5,6 5.6 Hz, H-5), 4.56 (d, 1H, J3,4 1.5 Hz, H-3) 4.64 (d, 1H,
J1,1 19.5 Hz, H-1), 4.50 (d, 1H, H-10), 4.22 (ddd, 1H, J4,5 4.7 Hz, J4,F 8.5 Hz, H-4), 3.82 (ddd, 1H, J6,F
0
25.5 Hz, J6,6 14.1 Hz, H-6), 3.61 (ddd, 1H, J6 ,F 29.4 Hz, H-60); the 13C NMR data are essentially the
same as reported in Ref. 29; 13C NMR: δ 212.9 (C-2), 90.3 (J5,F 174.9 Hz, C-5), 74.6 (J3,F 2.0 Hz, C-3),
69.4 (J4,F 25.9 Hz, C-4) 66.2 (C-1), 51.2 (J6,F 19.0 Hz, C-6). Anal. calcd for C6H10O4FN3: C, 34.79; H,
4.87; found: C, 34.59; H, 4.98.
0
0
3.31. 5,6-Dideoxy-5-fluor-D-fructose 36
Compound 29 (200 mg, 0.97 mmol) were reacted according to the general procedure to give desired
20
1
fructose derivative 36 (126 mg, 63%). [α]D −43.0 (c 2.65 MeOH); H NMR (200 MHz, D2O): δ
0
4.90–4.55 (m, 2H, J5,6 6.4 Hz, J5,F 44.0 Hz, H-5, H-3), 4.63 (d, 1H, J1,1 19.5 Hz, H-1), 4.49 (d, 1H,
H-10), 3.95 (ddd, 1H, J4,F 7.5 Hz, J4,5 7.5 Hz, J3,4 1.6 Hz, H-4), 1.40 (dd, 3H, J6,F 25.9 Hz, H-6); 13C
NMR: δ 213.2 (C-2), 89.4 (J5,F 166.1 Hz, C-5), 74.7 (J3,F 2.9 Hz, C-3), 73.5 (J4,F 25.7 Hz, C-4), 66.1
(C-1), 16.8 (J6,F 21.5 Hz, C-6). Anal. calcd for C6H11O4F: C, 43.37; H, 6.67; found: C, 43.35; H, 6.78.
3.32. 5,6-Diazido-5,6-dideoxy-D-fructose 37
Starting from 30 (173 mg, 0.752 mmol) and applying the respective general procedure, 38 mg (22%) of
compound 37 were obtained. Fructose derivative 37 was a faintly yellow, unstable oil which decomposed
20
1
rapidly in the refrigerator. [α]D −122.5 (c 0.65, CHCl3); H NMR (200 MHz, CD3OD3): δ 4.56 (d,
1H, J1,1 19.2 Hz, H-1), 4.44 (d, 1H, H-10), 4.44 (d, 1H, J3,4 1.5 Hz, H-3), 3.86 (dd, 1H, J4,5 9.2 Hz, H-4),
0
3.80–3.67 (m, 2H, J6,6 13.0 Hz, J5,6 2.4 Hz, J5,6 7.0 Hz, H-5, H-6), 3.51 (dd, 1H, H-60); 13C NMR:
δ 213.6 (C-2), 77.0, 72.5 (C-3/C-4), 68.0 (C-1), 63.6 (C-5), 53.6 (C-6). Anal. calcd for C6H10O4N6: C,
31.31; H, 4.38; found: C, 31.22; H, 4.50.
0
0
3.33. 5,6-Dideoxy-D-threo-hex-2-ulose 38
The general isomerisation procedure was applied. Compound 31 (110 mg, 0.742 mmol) led to 60 mg
20
20
(55%) of compound 38. [α]D −16.8 (c 1.8, MeOH) [lit.30 [α]D −14.6 (c 1, MeOH)]. The NMR data
are identical with previously published values.30
Acknowledgements
We appreciate funding by the Austrian Fonds zur Förderung der Wissenschaftlichen Forschung,
Vienna, Projects 12569 MOP (to B. N.) and 10805 CHE (to A. E. S.). Glucose isomerase studies were
supported by the Jubiläumsfonds der Österreichischen Nationalbank, Project 6894. NOVO is thanked for

620
P. Hadwiger et al. / Tetrahedron: Asymmetry 11 (2000) 607–620
a gift of immobilised glucose isomerase (Sweetzyme T). NMR measurements were conducted by Dr. H.
Weber and Ing. C. Illascewicz.
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