Synthetic applications of glucose isomerase: Isomerisation of C-5-modified (2R,3R,4R)-configured hexoses into the corresponding 2-ketoses

Article abstract of DOI:10.1016/S0008-6215(99)00119-6

Immobilised glucose isomerase (EC 5.3.1.5) accepted various (2R,3R,4R)-configured hexoses such as 5-deoxy-D-ribo-hexose, 5-azido-5-deoxy-D-allose, as well as the corresponding epimer at C-5, 5-azido-5-deoxy-L-talose, as substrates. From the resulting azid

Full text of DOI:10.1016/S0008-6215(99)00119-6

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Carbohydrate Research 319 (1999) 55–62
Synthetic applications of glucose isomerase:
isomerisation of C-5-modified (2R,3R,4R)-configured
hexoses into the corresponding 2-ketoses
Martin H. Fechter, Arnold E. Stu¨tz *
Institut fu¨r Organische Chemie der Technischen Uni6ersita¨t Graz, Stremayrgasse 16, A-8010 Graz, Austria
Received 5 April 1999; accepted 4 May 1999
Abstract
Immobilised glucose isomerase (EC 5.3.1.5) accepted various (2R,3R,4R)-configured hexoses such as 5-deoxy-
ribo-hexose, 5-azido-5-deoxy- -allose, as well as the corresponding epimer at C-5, 5-azido-5-deoxy- -talose, as
substrates. From the resulting azidodeoxyketoses, 5-azido-5-deoxy- -psico- and - -tagatopyranose, the powerful
-galactosidase inhibitors 2,5-dideoxy-2,5-imino- -galactitol and - -altritol were obtained in one additional step.
© 1999 Elsevier Science Ltd. All rights reserved.
D-
D
L
D
L
D
D
D
Keywords: -Allofuranose; 2,5-Dideoxy-2,5-iminoalditol; Galactosidase inhibitor; Glucose isomerase; L-Tagatopyranose; D-Psi-
D
copyranose
strate reported was the conversion of 6-deoxy-
6-thio- -glucose into the corresponding
-fructopyranose [3]. Subsequently, in a de-
tailed investigation, Bock and co-workers dis-
covered that -glucose derivatives bearing
modifications at C-6 or C-3 were converted by
the enzyme of a Streptomyces species in yields
varying between about 10 and 40%. In con-
1. Introduction
D
D
Microbial glucose isomerases (EC 5.3.1.5)
catalyse the conversion of
D
-glucose (1) into
D
D-fructose (2, Scheme 1) and are, in immo-
bilised form, widely employed on a large scale
in the industrial exploitation of this economi-
cally important transformation [1]. Most of
trast, epimers of
D
-glucose such as
D
-man-
nose, -allose, -galactose, as well as
D
D
L
-idose,
these enzymes function in vivo as
isomerases, their KM values with -xylose be-
ing one to two orders of magnitude smaller
than those with -glucose as substrate [2]. To
D-xylose
were not accepted as substrates [4]. An impor-
tant finding was the quantitative conversion of
D
5-deoxy-D-xylo-hexofuranose
(‘‘5-deoxy- -
D
D
glucose’’) into the corresponding 2-ketohex-
opyranose. These results were reproduced and
extended by Wong and his group, who em-
ployed glucose isomerase for the conversion of
gain insight into the substrate tolerance of
glucose isomerase, several investigators have
probed the enzyme with a wide range of un-
natural aldoses as well as 2-ketoses. The first
successful transformation of an unnatural sub-
enzymatically prepared unnatural
into the corresponding -glucopyranose
derivatives [5–7]. By this means, diastereo-
meric mixtures that contained -sorboses,
which were obtained from an aldolase
D-fructoses
D
* Corresponding author. Tel.: +43-316-873-8247; fax: +
43-316-873-8740.
E-mail address: stuetz@orgc.tu-graz.ac.at (A.E. Stu¨tz)
L
0008-6215/99/$ - see front matter © 1999 Elsevier Science Ltd. All rights reserved.
PII: S0008-6215(99)00119-6

56
M.H. Fechter, A.E. Stu¨tz / Carbohydrate Research 319 (1999) 55–62
2. Results and discussion
Some
hibit side activities towards (2R,3R,4R)-
configured aldoses such as -ribose [2,12,13]
and, in rare cases as with the enzyme from
Streptomyces albus, -allose is also a substrate
D
-xylose (
D
-glucose) isomerases ex-
D
Scheme 1.
D
[14]. Based on previous findings [8,9] that ring
enlargement or other means of strain release
in the course of the enzyme-catalysed aldose-
to-ketose isomerisation enhance the conver-
sion rate, we felt that C-5-modified
aldohexoses with the (2R,3R,4R)-configura-
tion might also be accepted as substrates by
Sweetzyme T, which also happens to stem
from a Streptomyces species.
or transketolase that catalysed the car-
bonꢀcarbon bond-forming step, could be con-
veniently separated, as these compounds were
not isomerised to
L
-idose derivatives [6].
Recently, we were able to report several
preparatively useful extensions of the glucose
The aldofuranoses employed in this study
were prepared from easily available 1,2-O-iso-
isomerase-catalysed
reaction.
Following
Bock’s results, it could be demonstrated that
immobilised glucose isomerase (Sweetzyme T)
propylidene-protected 5-deoxy-
furanose (3 [15,16]), 5-deoxyfluoro- (4 [17])
and 5-azidodeoxy- -idofuranose (5 [18]), and
5-azidodeoxy- -glucofuranose (6 [18,19]), re-
D-xylo-hexo-
quantitatively converted 5-modified
D-gluco-
L
furanoses into the corresponding -fructopy-
D
D
ranoses [8], the driving force of the reaction
being attributed to the release of ring strain in
the starting materials. Furthermore, it was
spectively, according to Scheme 2.
Regioselective O-tritylation of O-6 in these
intermediates provided 6-O-trityl derivatives 7
[20,21] as well as 8–10 which, upon oxidation
employing pyridinium chlorochromate in
dichloromethane in the presence of molecular
sieves and excess sodium acetate as buffer,
furnished 3-uloses 11–14 in yields between 60
and 70%. Compounds 12–14 were found to
be unstable due to the b-positioned leaving
group at C-5 with respect to the ketone and
were immediately employed in the following
step. Their reduction with sodium borohy-
dride in methanol proceeded with complete
stereoselectivity and furnished the desired
(2R,3R,4R)-configured sugar derivatives 15
[20] and 16–18. Conventional deprotection
with acidic ion-exchange resin in acetonitrile–
water mixtures at 50 °C gave free aldoses 19
[22,23], as well as 20–22, in satisfactory over-
all yields.
found that
rearrangement to give the corresponding
L
-idofuranoses also undergo this
L
-
sorbo isomers in high yields. Based on the
observation that the five-membered ring in
these aldofuranoses, due to steric crowding of
substituents, is obviously highly unstable, we
expected that 5-modified
D
-xylofuranoses, as
well as 5,6-dimodified -glucofuranose deriva-
D
tives, might give access to rare open-chain
2-ketoses when exposed to Sweetzyme T.
Gratifyingly, this could be shown for either
series of compounds [9] as well as, very re-
cently, for 5,6-dimodified analogues of
L
-
idose, the isomerisation products of which
have proven to be very useful in the synthesis
of a range of interesting glycosidase inhibitors
[10]. In a search for additional applications of
this approach, the behaviour of selected
(2R,3R)-configured aldopentoses towards this
enzyme has recently been investigated [11].
From the encouraging results obtained in this
Glucose isomerase-catalysed transformation
into the corresponding ketoses 23–26 was per-
formed at 65 °C employing a three-fold excess
of immobilised enzyme (w/w) in neutral
aqueous solutions containing small amounts
of magnesium sulfate. Gratifyingly, in all four
cases investigated in this study, NMR spectra
of the crude reaction mixtures revealed that a
study, we concluded that
D
-allose as well as
L
-talose derivatives with modifications at C-5,
some of which could be highly useful interme-
diates to prepare glycosidase inhibitors, might
also be worthwhile investigating.

M.H. Fechter, A.E. Stu¨tz / Carbohydrate Research 319 (1999) 55–62
57
Scheme 2.
time, to be able to convert (2R,3R,4R)-
configured aldohexoses modified at C-5 into
the corresponding ketopyranoses, the latter
being obtained in preparatively useful propor-
3:2 ratio of the respective starting material
and the resulting ketopyranose was obtained.
From these, the desired products were isolated
by chromatography on silica gel employing
ethyl acetate as the eluant. Isolated yields
ranged from 30 to 37%. The recovered aldo-
furanoses can be recycled. Consequently, these
figures correspond to yields of over 80% by
conversion.
tions. As was previously observed with
D
-
gluco- and -ido-configured aldofuranoses [8],
L
neither the nature of the substituent at C-5
nor the configuration at this centre appear to
have any influence on the efficiency of the
reaction. This transformation allows access to
a variety of rare ketose derivatives not readily
Contrasting the results of other workers, a
1:1 mixture of 2,5-dideoxy-2,5-imino-
titol (27 [24]) and - -altritol (28 [25,26]) was
formed from 5-azido-5-deoxy- -tagatopyra-
D-galac-
L
L
nose (25) by catalytic hydrogenation over pal-
ladium-on-charcoal (10%) at ambient pressure
and concomitant intramolecular reductive am-
ination. When 5-azido-5-deoxy- -psicopyra-
D
nose (26) was subjected to the reaction
conditions, an 8:1 ratio of 2,5-dideoxy-2,5-
imino-
ing
was obtained (Scheme 3).
D
-altritol (29 [27]) and the correspond-
D
-allo-configured pyrrolidine derivative 30
In conclusion, immobilised glucose iso-
merase (Sweetzyme T) was found, for the first
Scheme 3.

58
M.H. Fechter, A.E. Stu¨tz / Carbohydrate Research 319 (1999) 55–62
accessible by non-enzymatic methods, some of
which could be useful as intermediates in the
synthesis of biologically active compounds.
This could be shown with the synthesis of
compound 27, which has recently been found
to be a powerful inhibitor of b-galactosidase
[24], and analogues thereof.
evaporator or shaken at 60 °C for 3–8 h.
After the appropriate reaction time, the solids
were filtered off, the solution was concen-
trated under reduced pressure, and the residue
was chromatographed on silica gel. Parallel
control experiments were conducted with
Ca2+-inhibited enzyme, as well as without
enzyme, and gave less than 5% conversion
after reaction times of 16 and 24 h, respec-
tively, under otherwise identical conditions.
5-Deoxy-1,2-O-isopropylidene-6-O-triphen-
3. Experimental
ylmethyl-h-
ing the reported procedure [28], 5-deoxy-1,2-
-xylohexofuranose (3,
D
-xylohexofuranose (7).—Follow-
General methods.—Melting points were
recorded on a Tottoli apparatus and are un-
corrected. Optical rotations were measured on
a Jasco digital polarimeter or with a Perkin–
Elmer model 341 spectropolarimeter 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 as solvent for protected compounds,
and D2O for free sugars. Chemical shifts are
listed in l employing residual, not deuterated,
solvent as the internal standard. The signals of
the protecting groups were found in the ex-
pected regions and are not listed explicitly.
TLC was performed on precoated aluminum
sheets (E. Merck 5554). TLC plates were
stained with concd H2SO4 containing 5%
vanillin.
O-isopropylidene-a-
D
5.00 g, 24.5 mmol) was 6-O-tritylated. Com-
pound 7 was obtained as an off-white wax
(9.50 g, 87%): [h]D20 +4° (c 1.3, chloroform)
1
lit. +3.9° [20]; H NMR (300 MHz, CDCl3):
l 5.95 (d, 1 H, J1,2 3.7 Hz, H-1), 4.58 (d, 1 H,
H-2), 4.43 (m, 1 H, J4,5 5.1 Hz, J4,5% 6.8 Hz,
H-4), 4.12 (s, 1 H, H-3), 3.35 (m, 3 H, H-6,
H-6% OH-3), 2.08 (m, 2 H, H-5, H-5%); 13C
NMR (75.5 MHz, CDCl3): l 104.3 (C-1),
85.3, 78.7, 75,4 (C-2, C-3, C-4), 60.6 (C-6),
28.4 (C-5). Anal. Calcd for C28H30O5: C,
75.31; H, 6.77. Found: C, 75.18; H, 6.81.
5-Deoxy-5-fluoro-1,2-O-isopropylidene-6-O-
triphenylmethyl-i- -idofuranose (8).—Follow-
L
ing the procedure for the preparation of
compound 7, 5-deoxy-5-fluoro-1,2-O-iso-
Detection of iminoalditols on TLC was per-
formed by employing a mixture of 10% am-
monium molybdate (w/v) in 10% aqueous
sulfuric acid containing 0.8% cerium sulfate
(w/v).
propylidene-b- -idofuranose (4, 2.33 g, 10.5
L
mmol) was 6-O-tritylated. Compound 8 was
obtained as a yellow foam (2.94 g, 60%): [h]D20
1
−87° (c 1.8, chloroform); H NMR (300
MHz, CDCl3): l 5.99 (d, 1 H, J1,2 3.7 Hz,
H-1), 4.86 (dddd, 1 H, J4,5 6.9 Hz, J5,6 4.8 Hz,
J5,6% 3.9 Hz, J5,F 47.9 Hz, H-5), 4.47 (d, 1 H,
H-2), 4.46 (m, 1 H, J3,4 2.6 Hz, J4,F 17.3 Hz,
H-4), 4.10 (bs, 1 H, H-3), 3.56 (ddd, 1 H, J6,6%
10.8 Hz, J6,F 20.4 Hz, H-6), 3.44 (ddd, 1 H,
J6%,F 25.2 Hz, H-6%) 2.49 (bs, 1 H, OH-3); 13C
NMR (75.5 MHz, CDCl3): l 105.0 (C-1), 91.6
(J5,F 174 Hz, C-5), 85.3 (C-2), 80.2, (J4,F 18.6
Hz, C-4), 75.4, (J3,F 6.9 Hz, C-3), 63.2, (J6,F
24.7 Hz, C-6). Anal. Calcd for C28H29FO5: C,
72.40; H, 6.29. Found: C, 72.45; H, 6.30.
5-Azido-5-deoxy-1,2-O-isopropylidene-6-O-
For column chromatography Silica Gel 60
(E. Merck) was used. Mixtures of ethyl acetate
and petroleum ether (1:10 to 3:1) were used
for TLC and column chromatography of pro-
tected compounds, and ethyl acetate, as well
as ethyl acetate–MeOH mixtures (10:1 to 4:1),
were employed for TLC and chromatography
of unprotected sugars. Free inhibitors were
chromatographed in 100:100:1 CHCl3–
MeOH–concd aq ammonia.
General method 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% aq solution of
MgSO4 and 4 equiv (w/w) of immobilised
glucose isomerase (Sweetzyme T, Novo) were
added, and the mixture was spun on a rotary
triphenylmethyl-i- -idofuranose (9).—Follow-
ing the procedure for the preparation of
L
compound 7, 5-azido-5-deoxy-1,2-O-isopropy-
lidene-b- -idofuranose (5, 2.78 g, 11.3 mmol)
L

M.H. Fechter, A.E. Stu¨tz / Carbohydrate Research 319 (1999) 55–62
59
2.30 (dddd, 1 H, H-5), 2.03 (dddd, 1 H, H-5%);
13C NMR (75.5 MHz, CDCl3): l 211,3 (C-3)
103.1 (C-1), 76.5, 76,2 (C-2, C-4), 58.4 (C-6),
31.6 (C-5). Anal. Calcd for C28H28O5: C,
75.66; H, 6.35. Found: C, 75.78; H, 6.43.
5-Deoxy-5-fluoro-1,2-O-isopropylidene-6-O-
was 6-O-tritylated. Compound 9 was obtained
as an off-white foam (5.31 g, 98%): [h]2D0 −19°
1
(c 0.6, chloroform); H NMR (300 MHz,
CDCl3): l 5.94 (d, 1 H, J1,2 3.7 Hz, H-1), 4.48
(d, 1 H, H-2), 4.15 (dd, 1 H, J2,3 2.6 Hz, J4,5
7.7 Hz, H-4), 4.05 (dd, 1 H, 80.2, J3,OH-3 4.8
Hz, H-3), 3.70 (m, 1 H, H-5), 3.41 (d, 2 H, J5,6
5.6 Hz, H-6, H-6%) 2.60 (d, 1 H, OH-3); 13C
NMR (75.5 MHz, CDCl3): l 104.8 (C-1),
85.4, 81.1, 75,4 (C-2, C-3, C-4), 64.0, 61.0
(C-5, C-6). Anal. Calcd for C28H29N3O5: C,
68.98; H, 6.00. Found: C, 68.89; H, 5.95.
5-Azido-5-deoxy-1,2-O-isopropylidene-6-O-
triphenylmethyl-i- -lyxo-hex-3-ulofuranose
L
(12).—Following the procedure for the prepa-
ration of compound 11, compound 8 (2.84 g,
6.11 mmol) was oxidized to yield unstable
product 12 (1.89 g, 67%) as a slightly yellow
syrup that was immediately used in the next
step.
triphenylmethyl-h- -glucofuranose (10).—Fol-
D
5-Azido-5-deoxy-1,2-O-isopropylidene-6-O-
lowing the procedure for the preparation of
triphenylmethyl-i- -lyxo-hex-3-ulofuranose
L
compound 7, 5-azido-5-deoxy-1,2-O-isopropy-
(13).—Applying the oxidation procedure to
compound 9 (5.20 g, 10.7 mmol) gave product
13 (3.53 g, 68%) as a decomposing yellow
syrup that had to be immediately employed
for the next step.
lidene-b- -idofuranose (6, 2.35 g, 9.6 mmol)
L
was 6-O-tritylated. Compound 10 was ob-
tained as a slightly yellow foam (4.59 g, 98%):
1
[h]2D0 +26° (c 0.9, chloroform); H NMR (300
MHz, CDCl3): l 5.91 (d, 1 H, J1,2 3.6 Hz,
H-1), 4.51 (d, 1 H, H-2), 4.28 (dd, 1 H, J3,4 2.6
Hz, J3,OH-3 4.4 Hz, H-3), 4.17 (dd, 1 H, J4,5 8.3
Hz, H-4), 3.88 (ddd, 1 H, H-5), (dd, 1 H, J5,6
3.2 Hz, J6,6% 10.1 Hz, H-6), (dd, 1 H, J5,6% 6.7
Hz, H-6%), 2.45 (d, 1 H, OH-3); 13C NMR
(75.5 MHz, CDCl3): l 105.1 (C-1), 85.2, 78.7,
75,3 (C-2, C-3, C-4), 64.0, 60.2 (C-5, C-6).
Anal. Calcd for C28H29N3O5: C, 68.98; H,
6.00. Found: C, 68.92; H, 6.13.
5-Azido-5-deoxy-1,2-O-isopropylidene-6-O-
triphenylmethyl - h - - ribo - hex - 3 - ulofuranose
D
(14).—Compound 10 (3.93 g, 8.06 mmol) was
oxidized according to the procedure given for
the preparation of ketone 11 to furnish un-
stable ulose 14 (2.57 g, 66%) as an off-white
syrup that had to be immediately taken to the
next step: 1H NMR (300 MHz, CDCl3): l 5.82
(d, 1 H, J1,2 4.4 Hz, H-1), 4.36 (d, 1 H, H-2),
3.92 (m, 2 H, H-4, H-5), 3.53 (dd, 1 H, J5,6 6.4
Hz, J6,6% 9.4 Hz, H-6), 3.24 (dd, 1 H, J5,6% 8.3
Hz, H-6%); 13C NMR (75.5 MHz, CDCl3): l
208.2 (C-3) 103.6 (C-1), 80.0, 79,0 (C-2, C-4),
62.8, 61.1 (C-5, C-6).
5-Deoxy-1,2-O-isopropylidene-6-O-triphenyl-
methyl-h- -erythro-hex-3-ulofuranose (11).—
D
To a 5% solution of compound 7 (7.30 g, 16.3
mmol) in dry CH2Cl2, pyridinium chlorochro-
mate (8.5 g, 39.5 mmol), powdered molecular
5-Deoxy-1,2-O-isopropylidene-6-O-triphenyl-
,
sieves (3 A) and sodium acetate (7.5 g) were
methyl-h- -ribo-hexofuranose (15).—To a 3%
D
added, and the mixture was stirred under
reflux until quantitative conversion of the
starting material was indicated by TLC. After
removal of solids by filtration, chromium salts
were precipitated by addition of diethyl ether.
The filtrate was dried (Na2SO4) and concen-
trated under reduced pressure. Chromato-
graphic purification of the residue yielded
compound 11 (4.93 g, 68%) as a slightly yel-
solution of ulose 11 (1.50 g, 3.37 mmol) in dry
MeOH, sodium tetrahydridoborate (160 mg,
4.21 mmol) was added portionwise over 3 h.
After complete conversion of the starting ma-
terial, the solution was treated with acidic
ion-exchange resin (Amberlite IR-120 [H+])
and, after removal of the resin by filtration,
concentrated several times from MeOH to
remove boric acid. Chromatography of the
oily residue gave compound 15 (1.37 g, 91%)
as a colourless syrup: [h]2D0 +18° (c 1.6, chlo-
low foam: [h]2D0 −5° (c 1.8, chloroform); H
1
NMR (300 MHz, CDCl3): l 5.67 (d, 1 H, J1,2
4.5 Hz, H-1), 4.55 (dd, 1 H, J4,5 3.4 Hz, J4,5%
5.8 Hz, H-4), 4.40 (d, 1 H, H-2), 3.37 (ddd, 1
H, J5,6 4.5 Hz, J5%,6 9.0 Hz, J6,6% 9.0 Hz, H-6),
3.14 (ddd, 1 H, J5%,6 3.6 Hz, J5,6% 9.0 Hz, H-6%),
1
roform), lit +18.5° [20]; H NMR (200 MHz,
CDCl3): spectral data were identical with
reported values [20]; 13C NMR (50.3

60
M.H. Fechter, A.E. Stu¨tz / Carbohydrate Research 319 (1999) 55–62
1
[a]2D0 +13° (c 0.8, chloroform); H NMR (300
MHz, CDCl3): l 5.81 (d, 1 H, J1,2 3.7 Hz,
H-1), 4.58 (dd, 1 H, J2,3 4.8 Hz, H-2), 4.08 (m,
1 H, H-3), 3.91 (m, 2 H, H-4, H-5), 3.45 (dd,
1 H, J5,6 3.9 Hz, J6,6% 10.1 Hz, H-6), 3.39 (dd,
1 H, J5,6% 6.8 Hz, H-6%), 2.64 (d, 1 H, J3,OH-3 8.7
Hz, OH-3); 13C NMR (75.5 MHz, CDCl3): l
104.0 (C-1), 80.0, 79.3, 71.9 (C-2, C-3, C-4),
63.4, 62.9 (C-5, C-6). Anal. Calcd for
C28H29N3O5: C, 68.98; H, 6.00. Found: C,
69.12; H, 6.08.
MHz, CDCl3): l 103.8 (C-1), 78.9, 77.8, 76.1
(C-2, C-3, C-4), 60.7 (C-6), 32.7 (C-5). Anal.
Calcd for C28H30O5: C, 75.31; H, 6.77. Found:
C, 75.22; H, 6.83.
5-Deoxy-5-fluoro-1,2-O-isopropylidene-6-O-
triphenylmethyl-i-
L
-talofuranose
(16).—In
analogy to the procedure for 15, compound 12
(1.89 g, 4.09 mmol) was reduced with sodium
tetrahydridoborate (250 mg, 6.59 mmol) to
yield product 16 (1.57 g, 83%) as a colourless
1
syrup: [h]2D0 −23° (c 1.4, chloroform); H
NMR (300 MHz, CDCl3): l 5.82 (d, 1 H, J1,2
3.8 Hz, H-1), 4.83 (dddd, 1 H, J5,F 47.5Hz,
H-5), 4.58 (dd, 1 H, H-2), 4.12 (ddd, 1 H, J2,3
5.1 Hz, J3,4 9.0 Hz, J3,OH-3 10.2 Hz, H-3), 3.92
(ddd, 1 H, J4,5 2.4 Hz, J4,F 24.9 Hz, H-4), 3.61
(ddd, 1 H, J5,6 7.1 Hz, J6,6% 10.6 Hz, J6,F 13.8
Hz, H-6), 3.39 (ddd, 1 H, J5,6% 4.2 Hz, J6%,F 25.3
Hz, H-6%) 2.53 (d, 1 H, OH-3); 13C NMR (75.5
MHz, CDCl3): l 104.4 (C-1), 89.8 (J5,F 179,6
Hz, C-5), 79.7, (J4,F 17.7 Hz, C-4), 78.5 (C-2),
70.9, (J3,F 6.2 Hz, C-3), 63.4, (J6,F 24.6 Hz,
C-6). Anal. Calcd for C28H29FO5: C, 72.40; H,
6.29. Found: C, 72.32; H, 6.33.
5-Deoxy- -ribo-hexofuranose (19).—A 1%
D
solution of compound 15 (700 mg, 1.57 mmol)
in 50% aq CH3CN was stirred with acidic
ion-exchange resin (Amberlite IR-120 [H+]) at
40 °C for 24 h. After removal of the resin and
concentration of the filtrate under reduced
pressure, the residue was chromatographed to
give free sugar 19 (225 mg, 88%) as a colour-
1
less syrup: H NMR (300 MHz, D2O): l 5.39
(d, 1 H, J1,2 1.6 Hz, H-1a), 5.24 (d, 1 H, J1,2
4.2 Hz, H-1b), a/b ratio 1:2; 13C NMR (75.5
MHz, D2O): l 101.9 (C-1b), 96.8 (C-1a), 80.3,
76.3, 75,0 (C-2b, C-3b, C-4b), 80.4, 74.5, 71,4
(C-2a, C-3a, C-4a), 59.5 (C-6b), 59.4 (C-6a),
37.4 (C-5b), 36.2 (C-5a). Anal. Calcd for
C8H12O5: C, 43.90; H, 7.37. Found: C, 43.76;
H, 7.43.
5-Azido-5-deoxy-1,2-O-isopropylidene-6-O-
triphenylmethyl-i-
L
-talofuranose
(17).—
Sodium tetrahydridoborate reduction (625
mg, 16.7 mmol) of compound 13 (3.53 g, 7.27
mmol) in dry MeOH in the presence of acidic
ion-exchange resin (Amberlite IR-120 [H+]),
to avoid azide reduction gave, after chro-
matography, product 17 (3.07 g, 88%) as a
yellow foam: [h]2D0 −3° (c 1.4, chloroform);
5-Deoxy-5-fluoro- -talofuranose (20).—Hy-
L
drolysis of compound 16 (800 mg, 1.72 mmol)
following the procedure for 19 yielded free
deoxyfluorotalose 20 (247 mg, 79%) as a
1
colourless oil: H NMR (300 MHz, D2O): l
1
1H NMR (300 MHz, H NMR (300 MHz,
5.39 (d, 1 H, J1,2 3.9 Hz, H-1b), 5.24 (s, 1 H,
H-1a), 4.71 (m, 1 H, J5,F 44.9 Hz, H-5a), 4.37
(dd, 1 H, J2,3 4.7 Hz, J3,4 7.0 Hz, H-3a), a/b
CDCl3): l 5.78 (d, 1 H, J1,2 3.7 Hz, H-1), 4.55
(dd, 1 H, H-2), 4.01 (ddd, 1 H, J2,3 5.3 Hz, J3,4
8.6 Hz, J3,OH-3 10.4 Hz, H-3), 3.78 (dd, 1 H,
J4,5 3.1 Hz, H-4), 3.64 (ddd, 1 H, H-5), 3.52
(dd, 1 H, J5,6 8.0 Hz, J6,6% 9.8 Hz, H-6), 3.45
(dd, 1 H, J5,6% 5.0 Hz, H-6%), 2.41 (d, 1 H,
OH-3); 13C NMR (75.5 MHz, CDCl3): l 104.3
(C-1), 80.0, 78.5, 72.3 (C-2, C-3, C-4), 64.2,
61.3 (C-5, C-6). Anal. Calcd for C28H29N3O5:
C, 68.98; H, 6.00. Found: C, 68.93; H, 6.12.
5-Azido-5-deoxy-1,2-O-isopropylidene-6-O-
13
ratio 3:1; C NMR (75.5 MHz, D2O): l 102.1
(C-1a), 97.5 (C-1b), 94.4 (J5,F 175 Hz, C-5a),
93.9 (J5,F 174 Hz, C-5b), 81.4 (J4,F 17.7 Hz,
C-4b), 81.0 (J4,F 17.6 Hz, C-4a), 75.8 (C-2a),
71.3 (C-2b), 71.1 (J3,F 6.3 Hz, C-3a), 71.0 (J3,F
5.6 Hz, C-3b), 62.0 (J6,F 21.8 Hz, C-6a, C-6b).
Anal. Calcd for C6H11FO5: C, 39.56; H, 6.09.
Found: C, 39.62; H, 6.21.
5-Azido-5-deoxy- -talofuranose (21).—Hy-
L
triphenylmethyl-h-D-allofuranose (18).—Ap-
drolytic removal of protecting groups from
azidodeoxy sugar 17 (540 mg, 1.10 mmol),
according to the procedure for 19 furnished
compound 21 (187 mg, 83%) as a colourless
plication of the procedure for the preparation
of compound 17 to ulose 14 (1.94 g, 4.00
mmol) employing sodium tetrahydridoborate
(334 mg, 8.79 mmol) yielded allose derivative
18 (1.57 g, 81%) as a slightly yellow foam:
1
syrup: H NMR (300 MHz, D2O): l 5.45 (d, 1
H, J1,2 3.8 Hz, H-1b), 5.31 (s, 1 H, H-1a), a/b

M.H. Fechter, A.E. Stu¨tz / Carbohydrate Research 319 (1999) 55–62
61
13
5-Azido-5-deoxy-
L
-tagatopyranose (25).—
ratio 2:1; C NMR (75.5 MHz, D2O): l 102.2
Application of the general isomerisation proce-
(C-1a), 97.6 (C-1b), 82.2 (C-4b), 82.0 (C-4a),
76.0, 72.3 (C-2a, C-3a), 72.1, 71.5 (C-2b, C-3b),
65.7 (C-6a), 64.7 (C-6b), 62.6, 62.1 (C-5a, C-
5b). Anal. Calcd for C6H11N3O5: C, 35.13; H,
5.40. Found: C, 35.01; H, 5.43.
dure to azidodeoxyaldose 21 (187 mg, 0.91
mmol) furnished ketose 25 (62.7 mg, 34%): H
1
NMR (300 MHz, D2O), major anomer: l
4.03–3.88 (m, 3 H, H-3, H-6, H-6%), 3.87-3.76
(m, 2 H, H-1, H-4), 3.68 (m, 1 H, H-5), 3.58 (d,
5-Azido-5-deoxy-
D-allofuranose
(22).—
13
1 H, J 11.8 Hz, H-1%), anomeric ratio 8:1; C
Compound 18 (790 mg, 1.62 mmol) was sub-
jected to the hydrolysis of protecting groups as
reported above to yield free azidodeoxyallose
22 (259 mg, 78%) as a colourless oil: 1H NMR
(300 MHz, D2O): l 5.42 (d, 1 H, J1,2 4.0 Hz, H-
1a), 5.27 (d, 1 H, J1,2 0.9 Hz, H-1b), a/b ratio
5:2; 13C NMR (75.5 MHz, D2O): l 102.0 (C-
1b), 97.2 (C-1a), 82.9 (C-4a), 81.7 (C-4b), 76.2,
71.8, 66.3 (C-2b, C-3b, C-6b), 71.8, 70.8, 65.5
(C-2a, C-3a, C-6a), 61.9 (C-5a, C-5b). Anal.
Calcd for C6H11N3O5: C, 35.13; H, 5.40.
Found: C, 35.09; H, 5.49.
NMR (75.5 MHz, D2O), major anomer: l 99.2,
(C-2) 70.9, 70.5 (C-3, C-4), 64.9 (C-6), 61.4 (C-
1), 59.2 (C-5). Anal. Calcd for C6H11N3O5: C,
35.13; H, 5.40. Found: C, 35.02; H, 5.47.
5-Azido-5-deoxy- -psicopyranose (26).—
D
Compound 22 (177 mg, 0.86 mmol) was iso-
merised according to the general procedure to
yield psicose derivative 26 (58.8 mg, 33%) as a
1
colourless syrup: H NMR (300 MHz, D2O),
anomeric ratio 1:1: l 4.35 (t, 1 H, J 2.6 Hz),
4.23 (t, 1 H, J 4.0 Hz), 4.13 (dd, 1 H, J 2.0, 12.9
Hz), 3.97 (m, 2 H), 3.85 (dd, 1 H, J 1.8, 12.9
Hz), 3.84–3.68 (m, 6 H), 3.57 (d, 1 H, J 11.9
5 - Deoxy -
D
- erythro - hex - 2 - ulopyranose
(23).—Following the general procedure, com-
pound 19 (150 mg, 0.91 mmol) was exposed to
immobilised glucose isomerase (Sweetzyme T,
500 mg) for 8 h to yield ketose 23 (55.1 mg,
37%): 1H NMR (300 MHz, D2O), major
anomer: d 4.14 (ddd, 1 H, J5%,6 3.0 Hz, J5,6 5.2
Hz, J6,6% 12.0 Hz, H-6), 3.94 (ddd, 1 H, J5%,6% 2.9
Hz, J5,6%B1 Hz, H-6%), 3.82–3.70 (m, 2 H, H-3,
H-4), 3.74 (d, 1 H, J1,1% 11.7 Hz, H-1), 3.51 (d, 1
H, H-1%), 1.88 (m, 1 H, H-5), 1.71 (m, 1 H, H-
5%), anomeric ratio 11:3; 13C NMR (75.5 MHz,
D2O): l 101.9, 99.1 (C-2a,b), 69.2, 69.0, 67.4,
66.4, 65.4, 64.3, 60.1,56.2 (C-1, C-3, C-4, C-
6a,b), 31.6, 28.1 (C-5a,b). Anal. Calcd for
C6H12O5: C, 43.90; H, 7.37. Found: C, 43.77;
H, 7.41.
13
Hz), 3.45 (d, 1 H, J 11.7 Hz); C NMR (75.5
MHz, D2O): l 99.2, 98.7 (C-2a,b), 71.2, 70.0,
66.6, 66.5, 64.9, 64.1, 62.0, 60.6(C-1, C-3, C-4,
C6a,b), 58.1, 57.0 (C-5a,b). Anal. Calcd for
C6H11N3O5: C, 35.13; H, 5.40. Found: C, 35.07;
H, 5.49.
2,5-Dideoxy-2,5-imino-
-altritol (28).—To a 1% methanolic solution
D-galactitol (27) and
-
L
of azidodeoxyketose 25 (62.7 mg, 0.31 mmol),
palladium-on-carbon (10%, 50 mg) was added
and the mixture was stirred at ambient tem-
perature under an atmosphere of hydrogen.
(Caution: MeOH–Pd/C mixtures are a fire
hazzard!) After 1 h, the catalyst was removed
by filtration and the filtrate was concentrated
under reduced pressure to give a 1:1 mixture of
known iminoalditol 27 and epimer 28 (45.9 mg,
5-Deoxy-5-fluoro- -tagatopyranose (24).—
L
Aldose 20 (167 mg, 0.92 mmol) was isomerised
to ketose 24 (58.8 mg, 35%) following the gen-
eral procedure: 1H NMR (300 MHz, D2O), ma-
jor anomer: l 4.76 (m, 1 H, J5,F 45.0 Hz, H-5),
4.14 (m, 1 H, H-6), 3.96 (m, 2 H, H-3, H-4),
3.83 (m, 1 H, H-6%), 3.74, 3.73 (2d, 1 H, H-1),
3.55, 3.50 (2d, 1 H, H-1%), anomeric ratio 3:2;
13C NMR (75.5 MHz, D2O): l 99.1, 99.0 (C-
2a,b), 90.9 (J5,F 174 Hz), 89.2 (J5,F 174 Hz) [C-
5a,b)], 71.4 (J3,F 8.9 Hz), 64.4 [C-3a,b], 70.4
(J4,F 17.4 Hz), 69.0 (J4,F 27.3 Hz) [C-4a,b], 64.6,
64.4 (C-1a,b), 60.4 (J6,F 29.9 Hz), 59.3 (J6,F 19.6
Hz) [C-6a,b]. Anal. Calcd for C6H11FO5: C,
39.56; H, 6.09. Found: C, 39.41; H, 6.02.
1
92%). Compound 27: H NMR (300 MHz,
D2O): l 4.40 (dd, 2 H, J3,4 1.6 Hz, J2,3 4.4 Hz,
H-3, H-4), 3.89 (dd, 2 H, J1,2 5.3 Hz, J1,1% 11.7
Hz, H-1, H-6), 4.13 (dd, 2 H, J1%,2 6.8 Hz, H-1%,
13
H-6%), 3.48 (m, 2 H, H-2,H-5); C NMR (75.5
MHz, D2O): l 72.1 (C-3, C-4), 61.2 (C-2, C-5),
1
60.5 (C-1, C-6); lit. [24]: H NMR (500 MHz,
CD3OD) l 3.55–3.65 (m, 2 H), 3.88 (dd, 2 H, J
8.0, 12.0 Hz), 3.92 (dd, 2 H, J 5.0, 12.0 Hz),
4.3–4.4 (m, 2 H); 13C NMR (125 MHz,
CD3OD): l 59.45, 63.08, 71.69. Compound 28:
13C NMR (75.5 MHz D2O): l 73.8, 72.4 (C-3,
C-4), 62.5, 61.8, 61.5, 60.6 (C-1, C-2, C-5, C-6);

62
M.H. Fechter, A.E. Stu¨tz / Carbohydrate Research 319 (1999) 55–62
13
lit. [25]: C NMR, (50 MHz, CD3OD): l 61.8
(CH2), 62.4 (CH), 62.5 (CH2), 64.0 (CH), 73.4
(CH), 74.6 (CH).
References
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2,5-Dideoxy-2,5-imino-
-allitol (30).—Hydrogenolysis of azido-
D
-altritol (29) and -
D
deoxyketose 26 (58.8 mg, 0.29 mmol) yielded
an 8:1 mixture of iminodeoxyalditol 29 (37.4
mg, 80%) and its epimer at C-2, compound 30.
Inhibitor 29 was characterised as both the free
base and the corresponding hydrochloride.
Compound 30 could not be isolated from this
mixture in pure form. Complex 29: [h]2D0 +49°
1
(c 0.9, water), lit. [27]: +51.5° (c 1, water); H
NMR (300 MHz, D2O): l 4.21 (dd, 1 H, J2,3
4.0 Hz, J3,4 4.2 Hz, H-3), 4.03 (dd, 1 H, J4,5 8.5
Hz, H-4), 3.82 (dd, 1 H, J1,2 6.7 Hz, J1,1% 11.0
Hz, H-1), 3.78 (dd, 1 H, J5,6 4.1 Hz, J6,6% 11.7
Hz, H-6), 3.67 (dd, 1 H, J5,6% 5.9 Hz, H-6%),
3.66 (dd, 1 H, J1%,2 6.6 Hz, H-1%), 3.34 (m, 1 H,
H-2), 3.13 (m, 1 H, H-5); 13C NMR (75.5
MHz, D2O): l 74.6, 73.0 (C-3, C-4), 63.0,
62.4, 61.5, 60.7 (C-1, C-2, C-5, C-6). Anal.
Calcd for C6H13NO4: C, 44.17; H, 8.03.
Found: C, 44.07; H, 8.19. Compound 29·HCl:
1H NMR (300 MHz, D2O): l 4.37 (dd, 1 H,
J2,3 3.4 Hz, J3,4 3.9 Hz, H-3), 4.30 (dd, 1 H,
J4,5 9.1 Hz, H-4), 4.03 (dd, 1 H, J1,2 5.4 Hz,
J1,1% 12.1 Hz, H-1), 4.00 (dd, 1 H, J5,6 3.5 Hz,
J6,6% 12.5 Hz, H-6), 3.93 (dd, 1 H, J2,1% 8.0 Hz,
H-1%), 3.87 (dd, 1 H, J5,6% 5.8 Hz, H-6%), 3.78
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13
(m, 1 H, H-2), 3.66 (m, 1 H, H-5); C NMR
(75.5 MHz, D2O): l 72.3, 71.2 (C-3, C-4),
63.1, 62.7, 59.3, 58.6 (C-1, C-2, C-5, C-6).
Anal. Calcd for C6H13NO4·HCl: C, 36.10; H,
7.07. Found: C, 35.96; H, 7.18.
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Acknowledgements
Isomerization studies were kindly supported
by the Jubila¨umsfonds der Osterreichischen
8
Nationalbank, Project 6894. We appreciate
generous funding of glycosidase inhibitor re-
search by the Austrian Fonds zur Fo¨rderung
der Wissenschaftlichen Forschung, Vienna,
Project 10805 CHE. NOVO is thanked for the
generous gift of immobilised glucose iso-
merase (Sweetzyme T).
.