Convenient preparation of 3,5-anhydro- and 2,5-anhydropentofuranosides, and 5,6-anhydro-D-glucofuranose by use of the Mitsunobu reaction

Article abstract of DOI:10.1016/j.carres.2004.12.027

Methyl 3,5-anhydro-α-d-xylofuranosides are obtained by use of the Mitsunobu reaction from 2-O-protected methyl α-d-xylofuranosides, which are easily prepared from d-xylose. The Mitsunobu reaction of methyl 3-N-benzylamino-3-deoxy- and 3-azido-3-deoxyarabi

Full text of DOI:10.1016/j.carres.2004.12.027

Carbohydrate
RESEARCH
Carbohydrate Research 340 (2005) 587–595
Convenient preparation of 3,5-anhydro- and
2,5-anhydropentofuranosides, and 5,6-anhydro-D-glucofuranose
by use of the Mitsunobu reaction
Oliver Schulze,a,* Jurgen Vossa and Gunadi Adiwidjajab
¨
aInstitut fu¨r Organische Chemie der Universita¨t Hamburg, Martin-Luther-King-Platz 6, D-20146 Hamburg, Germany
bMineralogisch-Petrographisches Institut der Universita¨t Hamburg, Grindelallee 48, D-20146 Hamburg, Germany
Received 27 May 2004; accepted 31 December 2004
Available online 22 January 2005
Abstract—Methyl 3,5-anhydro-a-D-xylofuranosides are obtained by use of the Mitsunobu reaction from 2-O-protected methyl a-D-
xylofuranosides, which are easily prepared from D-xylose. The Mitsunobu reaction of methyl 3-N-benzylamino-3-deoxy- and
3-azido-3-deoxyarabinofuranosides, which are prepared from the conveniently available methyl 2,3-anhydro-a-D- and 2,3-anhydro-
a-L-lyxofuranosides by nucleophilic ring opening, yields the corresponding methyl 2,5-anhydro-a-D- and 2,5-anhydro-a-L-arabino-
furanosides. Ring opening of 3,5-anhydro-1,2-O-isopropylidene-a-D-xylofuranose with azide yields the corresponding 5-azido
derivative. The structure and configuration of the products is confirmed by NMR spectroscopy. 5,6-Anhydro-1,2-O-isopropylidene-a-D-
glucofuranose is formed by the Mitsunobu reaction of 1,2-O-isopropylidene-a-D-glucofuranose. Its structure is verified by single-
crystal X-ray diffraction analysis.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Keywords: Mitsunobu reaction; 2,5-Anhydro-arabinofuranosides; 3,5-Anhydro-xylofuranosides; 5,6-Anhydro-a-D-glucofuranose; Single-crystal
X-ray structural analysis
1. Introduction
2. Results and discussion
Bicyclic 2,5-anhydro- and 3,5-anhydrofuranosides are
versatile building blocks for syntheses. The fixed confor-
mation and the steric repulsion by the bridge will favour
the stereoselectivity of their reactions. As they exhibit
more or less ring strain, they are reactive compounds.
The anhydro bridges can, for instance, be opened by
nucleophiles to yield interesting products. Acid-catalyzed
hydrolysis and subsequent reduction should lead to oligo-
hydroxyoxetanes or -oxolanes. Furthermore, they repre-
sent precursors for anhydro nucleosides, which can be
used for the synthesis of locked nucleic acids (ÔLNAsÕ).
In the course of our investigations on thio-,1 seleno-2
and telluroanhydrofuranosides,2 we became interested
in new methods for the synthesis of the corresponding
oxygen analogues. Unexpectedly, attempts to apply the
Mitsunobu reaction to unprotected methyl pentofurano-
sides did not lead to the desired methyl 2,5-anhydro- or
3,5-anhydrofuranosides. Instead, methyl 2,3-anhydro-
furanosides (epoxysugars) were formed.3 Therefore, a
different synthetic strategy had to be developed that
would enforce an intramolecular attack of the hydroxy
group in the 2- or 3-position upon the 5-position of
the furanosides.
Derivatives of inexpensive D-xylose with a blocked hy-
droxy group in the 2-position should be suitable starting
compounds for the synthesis of methyl 3,5-anhydrofur-
anosides. For instance, 3,5-anhydro-1,2-O-isopropylid-
ene-a-D-xylofuranose (17) has been prepared from the
*
Corresponding author at present address: Universita¨tsklinikum
Hamburg, Klinik und Poliklinik fur Radiologie, Abt. fur Nuklear-
¨
¨
medizin, UKE-Zyklotron, Luruper Chaussee 149, D-22761 Ham-
burg, Germany. Tel.: + 49 40 8998 2963; fax: + 49 40 8998 2960;
e-mail: olli@ukezyk.desy.de
0008-6215/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2004.12.027

588
O. Schulze et al. / Carbohydrate Research 340 (2005) 587–595
corresponding 3,5-diol.4 Arabinose derivatives with a
protected hydroxy group in the 3-position, on the other
hand, could lead to methyl 2,5-anhydrofuranosides. In
principle, the corresponding D-lyxose derivatives are as
well suitable, but they are not as easily available. Fur-
thermore, they would yield highly strained products.
D-Ribose derivatives are ruled out on account of stereo-
chemical reasons.
4 was very suitable as a starting compound. It was
cleanly deprotected to methyl 2-O-(4-nitrobenzoyl)-a-
D-xylofuranoside (5) without any rearrangement as
established by single-crystal X-ray structural analysis
of 5 (Fig. 1). The Mitsunobu reaction of the diol 5 gave
the 3,5-anhydrofuranoside 6 in good yield. Debenzoyla-
tion of 6 with sodium methoxide, finally, led to unpro-
tected methyl 3,5-anhydro-a-D-xylofuranoside (7). The
corresponding b-anomer has been obtained by Bucha-
nan in a multi-step synthesis.8 The structure and config-
uration of 7 follows from its NMR spectra. In
particular, the chemical shifts d 4.78 for H-3 and d
74.9 for C-3 as well as the coupling constants J1,2
4.4 Hz, J2,3 6.2 Hz, J3,4 4.3 Hz, J4,5endo 2.4 Hz and
J4,5exo 4.5 Hz in 7 as compared with d 3.83 (H-3), d
62.1 (C-3), J1,2 ꢀ 0 Hz, J2,3 2.3 Hz, J3,4 ꢀ 0 Hz, J4,5endo
1.2 Hz and J4,5exo ꢀ 0 Hz in the 2,5-anhydro derivative
13 (see below) are indicative of the oxetane structure
and the a-D-xylo configuration of 7.
The epoxide 8 is conveniently available in two steps
from D-xylose or D-arabinose.3 Reaction of 8 with benz-
ylamine according to a literature procedure for the
preparation of aziridines from oxiranes in the carbohy-
drate series9 gave methyl 3-N-benzylamino-3-deoxy-a-
D-arabinofuranoside (9) as the only product of the
ring-opening reaction (Scheme 2). The nucleophilic at-
tack upon the epoxide ring exclusively occurred at the
3-position of 8. The structure of 9 follows from its
NMR spectra. The chemical shifts d(H-2) 4.06 and
d(C-2) 76.7 are higher than d(H-3) 3.03 and d(C-3)
65.9, as one would expect on account of the substituent
effects of oxygen and nitrogen. Subsequent Mitsunobu
reaction of 9 did, however, not yield the aziridine 10.
Instead, we obtained methyl 2,5-anhydro-3-N-benzyl-
amino-3-deoxy-a-D-arabinofuranoside (11). The reac-
D-Xylose can be transformed into the methyl 3,5-O-
isopropylidene-D-xylofuranosides 1 and 3 on a large
scale in two steps5 (Scheme 1). The anomers are easy
to separate by vacuum distillation.6 The free hydroxy
group in the 2-position of 1 and 3 can be protected with
a variety of electrophilic reagents to prevent the forma-
tion of 2,3-anhydrosugars under the conditions of the
Mitsunobu reaction. The 2-mesylates, which we have
prepared earlier,1 seemed not to be a good choice since
a mesylate substituent represents a good leaving group.
This could again give rise to the formation of 2,3-anhy-
dro instead of the desired 3,5-anhydro derivative. The 2-
O-(2-fluorobenzyl) derivative, on the other hand, can be
readily cyclised to the corresponding oxetano furano-
side.7 We have used it to prepare isonucleosides.7 It is,
however, not useful for the synthesis of free 3,5-anhy-
drofuranosides since the fluorobenzyl substituent cannot
easily be removed. Therefore, we have prepared the
2-acetate 2 and the 2-(4-nitrobenzoate) 4 as a compromise,
which should allow one to perform a straightforward
Mitsunobu reaction and, on the other hand, a facile
deprotection. The acetate 2 turned out to be not suitable
as precursor because the acid-catalysed cleavage of the
O-isopropylidene protecting group led to anomerisation
and also to the formation of undesired pyranosides. But
O
O
OMe
OMe
(a)
O
O
O
O
Me
Me
Me
Me
Me
Me
OH
OAc
O4
1
2
C1
C4
C3
C2
O
O
O
O
O
O
(b)
OMe
OpNB
OMe
OH
Me
Me
4
3
O
O
HO
(c)
(d)
OH
O
4
OMe
OR
R = pNB
OMe
OpNB
5
6
(e)
7 R = H
Scheme 1. Reagents: (a) AcCl, pyridine; (b) 4-nitrobenzoyl chloride,
pyridine; (c) AcOH–H2O; (d) DIAD, PPh3, pyridine; (e) NaOMe,
MeOH. pNB = 4-nitrobenzoyl.
Figure 1. ORTEP view of the single-crystal X-ray diffraction structure
of methyl 2-O-(4-nitrobenzoyl)-a-D-xylofuranoside (5) with atomic
numbering. Thermal ellipsoids are drawn on the 50% probability level.

O. Schulze et al. / Carbohydrate Research 340 (2005) 587–595
589
O
N
HO
10
11
OMe
O
O
O
HO
HO
(a)
CH2 Ph
HO
(b)
OMe
OMe
NH CH2 Ph
O
O
8
9
OMe
NH CH2 Ph
O
O
HO
O
(c)
(b)
HO
8
OMe
OMe
O
N3
N3
(b)
12
13
O
O
OMe
OMe
OMe
(c)
N3
N3
HO
HO
OH
O
O
14
15
16
Scheme 2. Reagents: (a) PhCH2NH2; (b) DIAD, PPh3, pyridine; (c) NaN3/NH4Cl, aq EtOH.
tion of the epoxide 8 with sodium azide gave methyl 3-
azido-3-deoxy-a-D-arabinofuranoside (12).10 It was
again the only product. The corresponding 2-azido deriv-
ative was not formed. The position of the nitrogen sub-
stituent at C-3 in 11 and 12 is once more obvious from
the NMR spectra. As in the case of 9, d(H-2) > d(H-3)
and d(C-2) > d(C-3) for the benzylamino 11 and the azi-
do derivative 12 (see Experimental). The Mitsunobu
reaction of 12 led to the expected methyl 2,5-anhydro-
3-azido-3-deoxy-a-D-arabinofuranoside (13).
Methyl 2,3-anhydro-a-L-lyxofuranoside (14) is the
enantiomer of 8. It can be prepared in two steps from inex-
pensive L-arabinose.3 In an identical reaction sequence as
for 13, 14 was transformed into methyl 2,5-anhydro-3-
azido-3-deoxy-a-L-arabinofuranoside (16) via methyl
3-azido-3-deoxy-a-L-arabinofuranoside (15). The anhy-
dro-azido sugars 13 and 16 represent another pair of
enantiomers. Their NMR spectroscopic data agree,
therefore, within the limits of experimental deviations.
Although oxetanes are not as highly strained com-
pounds as oxiranes, ring opening with nucleophiles is
possible. We have studied the reaction of the 3,5-anhy-
drofuranose 174 with sodium azide hoping to obtain
a 3-azido derivative by nucleophilic attack at the 3-
position. But the displacement reaction took place at
C-5, and 5-azido-5-deoxy-1,2-O-isopropylidene-a-D-xylo-
furanose (18) was formed (Scheme 3). The determina-
tion of its structure by NMR techniques was not quite
straightforward since hydroxy and azido groups exhibit
very similar effects on the chemical shifts. Fortunately,
however, the corresponding 3-(4-nitrobenzoate) 19 was
a crystalline compound, and its single-crystal X-ray dif-
fraction analysis answered the structural question (cf.
Fig. 2).
Since we had been able to prepare the desired 2,5-
anhydro- and 3,5-anhydropentofuranosides from meth-
yl pentofuranosides with two free hydroxy groups we
focused our interest on the synthesis of more complex
O
O
O
N3
N3
(a)
(b)
O
OH
OpNB
Me
Me
Me
Me
Me
Me
O
O
O
O
O
O
17
18
19
Scheme 3. Reagents: (a) NaN3/NH4Cl, aq EtOH; (b) 4-nitrobenzoyl chloride, pyridine. pNB = 4-nitrobenzoyl.

590
O. Schulze et al. / Carbohydrate Research 340 (2005) 587–595
C3
C2
C4
C1
C4
O4
O4
C1
C3
C2
Figure 2. ORTEP views of the single-crystal X-ray diffraction structures of 5-azido-5-deoxy-1,2-O-isopropylidene-3-O-(4-nitrobenzoyl)-a-D-
xylofuranose (19) and 5,6-anhydro-1,2-O-isopropylidene-a-D-glucofuranose 21 with atomic numbering. Thermal ellipsoids are drawn on the 50%
probability level.
monosaccharides with three free hydroxy groups. In
particular, cheap 1,2-O-isopropylidene-a-D-glucofura-
nose 20 seemed to be an interesting starting compound
for the synthesis of anhydro derivatives. Several possi-
bilities are thinkable for the intramolecular Mitsunobu
reaction of 20:
HO
HO
O
O
O
H
H
(a)
OH
OH
Me
Me
Me
Me
O
O
O
O
20
21
• Attack of the hydroxy group in the 3-position upon
C-5 under inversion of the configuration should give
an oxetane derivative with the L-ido configuration.
• Attack of the hydroxy group in the 3-position upon
C-6 should give an oxolane derivative with the D-
gluco configuration.
• Attack of the hydroxy group in the 6-position upon
C-5 under inversion of the configuration should give
an oxirane derivative with the L-ido configuration.
• Attack of the hydroxy group in the 3-position upon
an intermediately formed oxirane under ring open-
ing/ring closure should give the corresponding oxe-
tanes or oxolanes.
Scheme 4. Reagents: (a) DIAD, PPh3, pyridine.
are, for instance, useful for the preparation of 5-
thiohexoses.11
3. Experimental
3.1. General methods
• Attack of the hydroxy group in the 5-position upon
C-6 should give an oxirane with the D-gluco
configuration.
Melting points (corrected) were determined by use of an
electrothermal apparatus. IR spectra (KBr pellets or
films) were measured with an ATI Mattson Genesis
spectrometer. NMR spectra were recorded with Bruker
AMX 400 and DRX 500 spectrometers in CDCl3 if not
stated otherwise. Chemical shifts d (ppm) are related to
Me4Si (1H and 13C). Standard correlation techniques
were used for assignments. Mass spectra were measured
on a Varian CH 7 (EI, 70 eV) and a VG Analytical 70–
250 S (HRMS) apparatus. Optical rotations were mea-
sured on a Perkin–Elmer 341 polarimeter. Thin-layer
chromatography (TLC) was carried out on E. Merck
PF254 foils (detection: UV light, EtOH–H2SO4 spray/
200 °C), and column chromatography on E. Merck Kie-
We obtained one single product from the Mitsunobu
reaction of 20. According to its NMR spectra (see
Experimental) and especially upon an X-ray structural
analysis (cf. Fig. 2) this product was determined to be
the oxirane, 5,6-anhydro-1,2-O-isopropylidene-a-D-glu-
cofuranose (21) (Scheme 4). Thus, our method provides
a 5,6-anhydrohexofuranose in one step, whereas known
syntheses for this type of compounds require substan-
tially more steps. The 5,6-anhydrohexofuranoses are
valuable starting compounds for further syntheses. They

O. Schulze et al. / Carbohydrate Research 340 (2005) 587–595
591
selgel 60 (70–230 mesh). Solvents were purified and
dried according to standard laboratory procedures.12
The structures were solved by direct methods using the
SIR-97 program13 and the SHELXL-97 program.14 The
Cremer–Pople puckering parameters (Table 2) were
calculated with the PLATON program.15
3.2. Single-crystal X-ray structural analyses
The crystal data and a summary of experimental details
for 5, 19 and 21 are given in Table 1. Data collection was
performed on a Kappa CCD Nonius diffractometer,
with graphite-monochromated Mo Ka radiation (wave-
3.3. Starting materials
Methyl 3,5-O-isopropylidene-b-D-xylofuranoside (1)
and -a-D-xylofuranoside (3) were prepared according
to a literature procedure.5 The anomers were separated
by vacuum distillation.6 Methyl 3-azido-3-deoxy-a-D-
arabinofuranoside (12)10 and 3,5-anhydro-1,2-O-isoprop-
ylidene-a-D-xylofuranose (17)4 were prepared as de-
scribed in the literature. Methyl 2,3-anhydro-a-O-lyxo-
˚
length 0.71073 A) in the rotation U scan mode. The
refinement method was full-matrix-block least-squares
on F2. Hydrogen positions were obtained by difference
Fourier synthesis. The H-atom refinement method was
difmap and geometrical in case of 5, and mixed in case
of 19 and 21. The absolute structure parameters (flack
values) were in accordance with the expected structure.
furanoside
(8)
and
methyl
2,3-anhydro-a-O-
lyxofuranoside (14) were prepared as described earlier.3
Table 1. Crystal data and structure refinement for 5, 19 and 21
5
19
21
Molecular formula
Molecular weight (gmolꢁ1
Temperature (K)
Crystal system
Space group
a (pm)
C13H15NO8
313.26
293(2)
C15H16N4O7
364.32
293(2)
C9H14O5
202.20
293(2)
)
Monoclinic
P21
974.9(1)
Monoclinic
P21
677.6(1)
Orthorhombic
P212121
543.0(1)
b (pm)
c (pm)
731.0(1)
698.3(1)
1829.9(1)
90.23(1)
928.8(1)
1997.2(1)
90.00
1065.5(1)
113.34(1)
697.19(14)
2
b (°)
3
˚
V (A )
865.84(18)
2
1.397
1007.3(2)
4
1.333
Z (molecules per cell)
Dcalcd (gcmꢁ3
Absorption coefficient (mmꢁ1
F(0 0 0)
Crystal size (mm)
)
1.492
0.126
328
)
0.113
380
0.109
432
0.33 · 0.26 · 0.21
2.08–27.49
0 6 h 6 12
ꢁ9 6 k 6 9
ꢁ13 6 l 6 12
13,343
0.51 · 0.41 0.33
3.01–27.53
0 6 h 6 8
ꢁ8 6 k 6 7
ꢁ23 6 l 6 23
5988
0.45 · 0.22 0.09
2.04–27.48
0 6 h 6 7
0 6 l 6 12
ꢁ25 6 l 6 25
11,694
h Range for data collection (°)
Index ranges
Reflections collected
Independent reflections
Reflections with [I P 2r(I)]
Function minimiseda
3191
3072
3026
2533
2297
1771
x = 0.0735
y = 0.0822
3191/1/248
0.985
x = 0.0676
y = 0.0735
3026/1/273
1.106
x = 0.0975
y = 0.0866
2297/0/160
1.015
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I P 2r(I)]
R1 = 0.0341
wR2 = 0.0992
R1 = 0.0357
wR2 = 0.1014
0.213 and ꢁ0.162
R1 = 0.0452
wR2 = 0.1135
R1 = 0.0581
wR2 = 0.1240
0.216 and ꢁ0.224
R1 = 0.0491
wR2 = 0.1153
R1 = 0.0739
wR2 = 0.1475
0.455 and ꢁ0.445
R Indices (all data)
ꢁ3
˚
Largest difference peak and hole (e A
)
a P
2
wðF 2o ꢁ F c2Þ ; w ¼ 1=½r2ðF o2Þ þ x2 þ yPŠ, where P ¼ ðF o2 þ 2F 2cÞ=3.
Table 2. Cremer–Pople puckering parameters
Compound
Atom sequence
Puckering parameters
Closest pucker descriptor
˚
Q(2) (A)
U (2) (°)
5
O(4)–C(1)–C(2)–C(3)–C(4)
O(4)–C(1)–C(2)–C(3)–C(4)
O(4)–C(1)–C(2)–C(3)–C(4)
0.432(2)
0.339(3)
0.362(2)
76.9(2)
317.3(5)
295.9(4)
Envelope C(2)-endo
Envelope C(4)-exo
Twist C(3)-endo, C(4)-exo
19
21

592
O. Schulze et al. / Carbohydrate Research 340 (2005) 587–595
1,2-O-isopropylidene-a-D-glucofuranose (20) was ob-
tained from Lancaster synthesis.
(2CHAr), 131.0 (2CHAr), 135.0 (C-1Ar), 150.8 (C-4Ar),
163.8 (C@O).
3.4. Methyl 2-O-acetyl-3,5-O-isopropylidene-b-D-xylo-
furanoside (2)
3.5.2. Methyl 2-O-(4-nitrobenzoyl)-a-D-xylofuranoside
(5). A solution of 4 (81.7 g, 231.3 mmol) in water
(75 mL) and HOAc (145 mL) was stirred at 50 °C for
4 h. After stirring overnight at room temperature, the
solvent was evaporated. After repeated co-distillation
with toluene 5 (74.1 g, ꢀ100%, contaminated with traces
Acetyl chloride (15.0 mL, 210.2 mmol) was dropped into
a solution of 1 (24.0 g, 117.4 mmol) in dry pyridine
(250 mL) at 0 °C within 30 min. After stirring for 1 h,
the reaction mixture was poured onto ice-water
(1000 mL) and extracted with CHCl3 (2 · 200 mL,
3 · 100 mL). The combined organic extracts were
washed with water (100 mL) and brine (6 · 100 mL
each). After drying over MgSO4 and evaporation of
the solvent, the residue was purified by vacuum distilla-
of toluene) was obtained as yellow crystals: mp 112 °C
20
(MeOH). ½aŠ +154.8 (c 1.0, CHCl3); Rf 0.62 (5:5:1 tolu-
D
ene–EtOAc–EtOH); IR: m 3453 (OH), 1729 (C@O), 1530
1
(NO2), 1351 (NO2) cmꢁ1 ; H NMR (400 MHz): d 2.67
(t, 1H, OH-5), 3.40 (s, 3H, OCH3), 3.65 (d, 1H, OH-
3), 3.98 (dd, 2H, H-5, H-50), 4.32 (dt, 1H, H-4), 4.78
(ddd, 1H, H-3), 5.07 (dd, 1H, H-2), 5.25 (d, 1H, H-1),
8.25 (ddd, 2H, ArH), 8.30 (ddd, 2H, ArH). J1,2 4.4,
tion to yield 2 (26.2 g, 106.3 mmol, 90.5%) as a pale-yel-
20
D
low syrup: bp 99 °C (0.4 mm); ½aŠ ꢁ56.2 (c 1.1,
0
J2,3 6.2, J3,4 7.4, J3, OH-3 7.2, J4,5 3.1, J4,5 3.1, J5, OH-5
CHCl3); Rf 0.64 (2:1 EtOAc–petroleum ether); IR: m
1
3
6.2, J5 , OH-5 6.2, JArH, ArH 9.1, JArH, ArH 2.0, JArH,
4
5
1750 (C@O) cmꢁ1; H NMR (400 MHz): d 1.38 (s, 3H,
0
4
2.1, JArH,
CH3), 1.39 (s, 3H, CH3), 2.10 (s, 3H, COCH3), 3.42 (s,
3H, OCH3), 3.83 (dd, 1H, H-5), 3.97 (dd, 1H, H-50),
4.20–4.25 (m, 2H, H-3, H-4), 4.92 (s, 1H, H-1), 5.06 (s,
2.1 Hz; 13C NMR (101 MHz): d
ArH
ArH
55.4 (OCH3), 61.8 (C-5), 74.9 (C-3), 76.6 (C-4), 82.4
(C-2), 100.0 (C-1), 123.6 (2CHAr), 131.1 (2CHAr),
137.8 (C-1Ar), 150.9 (C-4Ar), 165.0 (C@O).
1H, H-2). J4,5 4.9, J4,5 4.5, J5,5 12.0 Hz; 13C NMR
(101 MHz): 20.8 (COCH3), 21.1 (CH3), 26.9 (CH3),
55.2 (OCH3), 60.7 (C-5), 73.1 (C-4), 75.4 (C-3), 81.5
(C-2), 98.6 (CMe2), 108.1 (C-1), 169.5 (C@O). Anal.
Calcd for C11H18O6: C, 53.65; H, 7.37. Found: C,
53.25; H, 7.52.
0
0
3.5.3. Methyl 3,5-anhydro-2-O-(4-nitrobenzoyl)-a-D-
xylofuranoside (6). The reaction was carried out under
N2. Diisopropyl azodicarboxylate (0.3 mL, 1.53 mmol)
and subsequently a solution of 5 (0.23 g, 0.75 mmol) in
dry pyridine (0.5 mL) were added to a solution of triphen-
ylphosphine (0.40 g, 1.53 mmol) in dry pyridine (4 mL).
After 5 h at 80 °C the solvent was evaporated, and the
residue was filtered through silica gel (50 g, EtOAc).
Column chromatography (50 g silica gel, 1:2 petroleum
ether–EtOAc) yielded 6 as a yellow solid (containing
traces of diisopropyl hydrazodicarboxylate according
to the NMR spectra). The product was debenzoylated
3.5. Methyl 3,5-anhydro-a-D-xylofuranoside (7)
3.5.1. Methyl 3,5-O-isopropylidene-2-O-(4-nitrobenzoyl)-
a-D-xylofuranoside (4). A solution of 4-nitrobenzoyl
chloride (49.2 g, 265.1 mmol) in dry pyridine (490 mL)
was dropped into a solution of 3 (49.2 g, 240.9 mmol)
in dry pyridine (170 mL) at 0 °C. The solution was stir-
red overnight at room temp. Water (16 mL) was added.
The solvent was evaporated in a vacuum, and the resi-
due was dissolved in CHCl3 (340 mL). The solution
was washed with water (3 · 300 mL), with NaHSO4
solution (3 M, 3 · 300 mL) and again with satd NaH-
CO3 solution (3 · 300 mL each). After drying over
MgSO4, filtration and evaporation of the solvent 4
(81.7 g, 231.3 mmol, 96%) was obtained as a brown syr-
up that was used in the next step without further purifi-
cation. Rf 0.21 (10:1 toluene–EtOAc); IR: m 1733 (C@O),
´
by use of the Zemplen procedure without further purifi-
cation. Rf 0.75 (EtOAc); 1H NMR (400 MHz): d 3.45 (s,
3H, OCH3), 4.41 (dd, 1H, H-5endo), 4.81 (dd, 1H, H-
5exo), 5.05 (ddd, 1H, H-4), 5.38 (dd, 1H, H-3), 5.46
(dd, 1H, H-2), 5.61 (d, 1H, H-1), 8.22 (ddd, 2 H,
ArH), 8.29 (ddd, 2H, ArH). J1,2 4.0, J2,3 1.6, J3,4 4.5,
3
J4,5-endo 2.6, J4,5-exo 4.5, J5-endo,5-exo 7.9, JArH, ArH 8.9,
5
4
4JArH, ArH 2.1, JArH, ArH 2.1, JArH, ArH 2.0 Hz; 13C
NMR (101 MHz): 56.4 (OCH3), 75.4 (C-4), 76.6 (C-5),
79.5 (C-2), 87.5 (C-3), 104.7 (C-1), 123.6 (2CHAr),
131.0 (2CHAr), 134.8 (C-1Ar), 150.8 (C-4Ar), 163.8
(C@O).
1
1530 (NO2), 1318 (NO2) cmꢁ1; H NMR (400 MHz): d
1.42 (s, 3H, CH3), 1.46 (s, 3H, CH3), 3.39 (s, 3H,
OCH3), 3.93 (dd, 1H, H-5), 4.10 (dd, 1H, H-50), 4.22
(ddd, 1H, H-4), 4.57 (dd, 1H, H-3), 5.28 (dd, 1H, H-
2), 5.37 (d, 1H, H-1), 8.23 (ddd, 2H, ArH), 8.29 (ddd,
3.5.4. Methyl 3,5-anhydro-a-D-xylofuranoside (7).
Compound 6 was dissolved in a mixture of benzene
and MeOH (1:1, 20 mL). A solution of NaOMe in
MeOH (1 mL) prepared from Na (0.05 g, 2.17 mmol)
was added. After 2 h at 40 °C the reaction mixture
was allowed to reach room temperature. Then the mix-
ture was neutralised with HOAc in MeOH, and the sol-
0
2H, ArH). J1,2 4.4, J2,3 2.0, J3,4 4.0, J4,5 4.2, J4,5 4.2,
3
4
5
0
J5,5 12.6, JArH, ArH 8.8, JArH, ArH 2.0, JArH, ArH 2.0,
4JArH, ArH 2.1 Hz; 13C NMR (101 MHz): d 20.8 (CH3),
27.6 (CH3), 56.2 (OCH3), 60.2 (C-5), 71.1 (C-4), 73.6
(C-3), 80.1 (C-2), 98.8 (CMe2), 101.8 (C-1), 123.6

O. Schulze et al. / Carbohydrate Research 340 (2005) 587–595
593
vent was evaporated. Chromatographic workup (50 g
silica gel, EtOAc) and distillation yielded 7 (0.05 g,
J5-endo,5-exo 8.2 Hz; 13C NMR (101 MHz): d 52.3
(PhCH2), 55.8 (OCH3), 63.1 (C-3), 72.0 (C-5), 75.6
(C-2), 77.8 (C-4), 106.6 (C-1), 127.0 (CHAr), 128.1
(2CHAr), 128.4 (2CHAr), 140.0 (C-1Ar); EIMS: m/z (%)
235 (1) [M+ꢀ], 204 (2) [M+ꢀꢁOCH3], 174 (36), 144 (5)
[M+ꢀꢁC7H7], 118 (5), 105 (4), 92 (16), 91 (100, C7H7+),
97 (20), 69 (13), 65 (22), 51 (6), 45 (12), 43 (12), 41 (9),
39 (10); HRMS Calcd for C13H17NO3: 235.1185. Found:
235.1208. Anal. Calcd for C13H17NO3: C, 66.36; H,
7.28; N, 5.95. Found: C, 65.17; H, 7.34; N, 5.85.
0.34 mmol, 45% total yield for this and the previous
20
D
step) as a colourless oil: bp 64 °C (0.5 mm); ½aŠ +92.8
(c 1.0, CHCl3); Rf 0.46 (EtOAc); IR: m 3441 (OH) cmꢁ1
;
1H NMR (500 MHz): d 2.91 (s, 1H, OH), 3.54 (s, 3H,
OCH3), 4.22 (d, 1H, H-2), 4.24 (dd, 1H, H-5endo), 4.70
(dd, 1H, H-5exo), 4.90 (ddd, 1H, H-4), 5.03 (d, 1H, H-
3), 5.34 (d, 1H, H-1). J1,2 3.8, J3,4 4.3, J4,5-endo 2.4,
J4,5-exo 4.5, J5-endo,5-exo 7.9 Hz; 13C NMR (101 MHz): d
56.9 (OCH3), 75.7 (C-2), 75.8 (C-4), 77.2 (C-5), 89.9
(C-3), 105.8 (C-3); EIMS: m/z (%) 129 (1), 117 (6), 116
(21) [M+ꢀꢁCH2O], 115 (10) [M+ꢀꢁOCH3], 101 (7), 88
(6), 87 (100), 86 (10), 85 (20), 84 (8), 83 (2), 75 (10), 74
(16), 73 (7), 72 (5), 71 (32), 69 (24), 68 (15), 61 (56), 60
(10), 59 (28), 58 (17), 57 (56), 56 (24), 55 (46), 54 (8),
45 (22). Anal. Calcd for C6H10O4: C, 49.31; H, 6.90.
Found: C, 48.88; H 7.06.
3.7. Methyl 2,5-anhydro-3-azido-3-deoxy-a-D-arabino-
furanoside (13)
Compound 1210 {0.47 g, 2.48 mmol; IR: m 3399 (OH),
1
2107 (N3) cmꢁ1; H NMR (400 MHz, D2O): d 3.25 (s,
3H, OCH3), 3.59 (dd, 1H, H-5), 3.66 (dd, 1H, H-50),
3.68 (dd, 1H, H-3), 3.89 (ddd, 1H, H-4), 4.03 (dd, 1H,
H-2), 4.80 (d, 1H, H-1). J1,2 1.5, J2,3 3.6, J3,4 6.5, J4,5
3.6. Methyl 2,5-anhydro-3-benzylamino-3-deoxy-a-D-
arabinofuranoside
5.2, J4,5 3.8, J5,5 12.3 Hz; 13C NMR (101 MHz, D2O):
d 55.4 (OCH3), 61.5 (C-5), 66.6 (C-3), 80.0 (C-2),
82.2 (C-4), 108.6 (C-1); EIMS: m/z (%) 158 (17)
[M+ꢀꢁOCH3], 151 (4), 115 (9), 87 (50), 74 (100), 69
(43); CIMS: m/z (%) 207 (100) [M++NH4], 175
(63), 164 (31), 162 (84)}, triphenylphosphine (1.29 g,
4.92 mmol) and diisopropyl azodicarboxylate (0.95
mL, 4.86 mmol) were refluxed (3 h) in dry pyridine
(14 mL). The solvent was evaporated, and the residue
was chromatographed twice (100 g silica gel each; (1)
1:1 EtOAc–hexane; (2) 1:2 EtOAc–pentane, Rf 0.35) to
yield 13 (0.28 g, 1.63 mmol, 66%) as a pale yellow oil.
Traces of diisopropyl hydrazodicarboxylate could not
be completely removed. Thus no correct elemental anal-
0
0
3.6.1. Methyl 3-benzylamino-3-deoxy-a-D-arabinofurano-
side (9). A solution of 83 (1.57 g, 10.74 mmol) in benz-
ylamine (10 mL) was stirred at 150 °C for 5 h. After
vacuum evaporation of the solvent (0.8 mm), the residue
was chromatographed (silica gel, 370 g, 3:1 EtOAc–
EtOH) to yield 9 (2.15 g, 8.49 mmol, 79%) as a pale-yel-
low syrup that was used for the Mitsunobu reaction
without further purification. Rf 0.56 (3:1 EtOAc–EtOH);
1H NMR (500 MHz): d 3.03 (d, 1H, H-3), 3.31 (s, 3H,
OCH3), 3.59 (dd, 1H, H-5), 3.74 (dd, 1H, H-50), 3.75
(d, 1H, PhCH), 3.85 (d, 1H, PhCH), 4.04 (ddd, 1H,
H-4), 4.06 (s, 1H, H-2), 4.83 (s, 1H, H-1), 7.22–7.33
1
ysis was obtained. H NMR (500 MHz): d 3.48 (s, 3H,
0
0
(m, 5H, ArH). J3,4 3.4, J4,5 2.7, J4,5 1.9, J5,5 11.7,
2JCH2 12.9 Hz; 13C NMR (126 MHz): d 52.0 (PhCH2),
54.7 (OCH3), 62.2 (C-5), 65.9 (C-3), 76.7 (C-2), 85.2
(C-4), 109.7 (C-1), 127.2 (CHAr), 128.2 (2CHAr), 128.5
(2CHAr), 139.3 (C-1Ar).
OCH3), 3.73 (d, 1H, H-5endo), 3.83 (d, 1H, H-3), 3.86
(dd, 1H, H-5exo), 4.26 (d, 1H, H-2), 4.60 (d, 1H, H-4),
4.92 (s, 1H, H-1). J2,3 2.3, J4,5-exo 1.2, J5-endo,5-exo
8.4 Hz; 13C NMR (101 MHz): d 56.8 (OMe), 62.1 (C-
3), 72.5 (C-5), 77.7 (C-2 or C-4), 77.8 (C-2 or C-4),
106.4 (C-1).
3.6.2. Methyl 2,5-anhydro-3-benzylamino-3-deoxy-a-D-
arabinofuranoside (11).
A
solution of
9
(0.80 g,
3.8. Methyl 3-azido-3-deoxy-a-L-arabinofuranoside (15)
3.16 mmol) in dry toluene (5 mL) was added to a solu-
tion of triphenylphosphine (0.85 g, 3.24 mmol) and
diisopropyl azodicarboxylate (0.6 mL, 3.07 mmol) in
dry toluene (35 mL) at 0 °C. After 2 h the reaction was
finished (TLC monitoring). The solvent was evaporated.
The residue was purified by column chromatography
A solution of 143 (0.93 g, 6.36 mmol), NaN3 (0.84 g,
12.9 mmol) and NH4Cl (0.82 g, 15.3 mmol) in EtOH
(19 mL) and water (4.5 mL) was refluxed for 76 h. After
evaporation of the solvent the residue was co-distilled
four times with toluene (20 mL each) and twice with
CHCl3 (20 mL each). Chromatography (50 g silica gel,
(100 g silica gel, 3:1 EtOAc–EtOH) to yield 11 (0.64 g,
20
D
2.72 mmol, 86%) as a yellow oil: ½aŠ +83.9 (c 1.0,
EtOAc, Rf 0.64) yielded 15 (1.16 g, 6.13 mmol, 96%) as
20
D
CHCl3); Rf 0.63 (3:1 EtOAc–EtOH); IR: m 3345
a colourless syrup: ½aŠ ꢁ165.5 (c 1.04, CHCl3); IR: m
1
(NH) cmꢁ1 ; H NMR (400 MHz): d 2.70 (s, 1H, NH),
3408 (OH), 2108 (N3) cmꢁ1
;
1H NMR (400 MHz,
3.24 (d, 1H, H-3), 3.39 (s, 3H, OCH3), 3.60 (d, 1H, H-
D2O): d 3.46 (s, 3H, OCH3), 3.79 (dd, 1H, H-5), 3.87
(dd, 1H, H-50), 3.89 (dd, 1H, H-3), 4.10 (ddd, 1H, H-
4), 4.23 (dd, 1H, H-2), 5.01 (d, 1H, H-1). J1,2 1.6, J2,3
5endo), 3.71 (dd, 1H, H-5exo), 3.79 (s, 2H, PhCH2),
4.16 (d, 1H, H-2), 4.39 (d, 1H, H-4), 4.79 (s, 1H,
H-1), 7.20–7.35 (m, 5H, ArH). J2,3 2.1, J4,5-exo 1.0,
3.7, J3,4 6.4, J4,5 5.2, J4,5 3.9, J5,5 12.3 Hz; 13C NMR
0
0

594
O. Schulze et al. / Carbohydrate Research 340 (2005) 587–595
(101 MHz, D2O): d 55.4 (OCH3), 61.5 (C-5), 66.6 (C-3),
80.0 (C-2), 82.2 (C-4), 108.6 (C-1); EIMS: m/z (%) 158
(6) [M+ꢀꢁOCH3], 115 (12), 87 (62), 74 (100), 69 (47);
CIMS: m/z (%) 207 (100) [M+ + NH4], 175 (65), 164
(35), 162 (87); Anal. Calcd for C6H11N3O4: C, 38.10;
H, 5.86; N, 22.21. Found: C, 37.14; H, 6.02; N, 20.52.
ing over MgSO4, filtration and evaporation of the sol-
vent, the residue was purified by chromatography
(100 g silica gel, 4:1 petroleum ether–EtOAc, Rf 0.31)
yielding 19 as a yellow syrup. Recrystallisation from
EtOH–ether yielded 19 (1.16 g, 3.18 mmol, 48%) as yel-
20
D
low needles: mp 71 °C (ether–EtOH); ½aŠ +11.9 (c 1.0,
CHCl3); IR: m 2141 (N3), 1724 (C@O), 1525 (NO2),
1
3.9. Methyl 2,5-anhydro-3-azido-3-deoxy-a-L-arabino-
furanoside (16)
1345 (NO2) cmꢁ1; H NMR (400 MHz): d 1.36 (s, 3H,
Me), 1.58 (s, 3 H, Me0), 3.57 (dd, 1H, H-5), 3.62 (dd,
1H, H-50), 4.55 (ddd, 1H, H-4), 4.71 (d, 1H, H-2), 5.50
(d, 1H, H-3), 6.06 (d, 1H, H-1), 8.21 (ddd, 2H, ArH),
Compound 16 was prepared as described for 13 from 15
(0.93 g, 4.92 mmol), triphenylphosphine (2.56 g,
0
8.32 (ddd, 2H, ArH). J1,2 3.8, J3,4 3.0, J4,5 5.7, J4,5
3
4
5
0
6.6, J5,5 12.9, JArH, ArH 9.0, JArH, ArH 2.1, JArH, ArH
9.76 mmol)
and
diisopropyl
azodicarboxylate
4
(1.90 mL, 9.72 mmol). Chromatography (twice, 100 g
silica gel each, 1:1 EtOAc–petroleum ether, Rf 0.61)
yielded 16 (0.60 g, 3.50 mmol, 71%) as a pale-yellow
2.1, JArH,
2.1 Hz; 13C NMR (101 MHz): d 21.2
ArH
(Me), 26.7 (Me0), 49.1 (C-5), 77.65 (C-3 or C-4), 77.68
(C-3 or C-4), 83.4 (C-2), 104.8 (C-1), 112.6 (CMe2),
123.8 (2CHAr), 130.9 (2CHAr), 134.3 (C-1Ar), 151.0 (C-
4Ar), 163.5 (C@O); EIMS: m/z (%) 349 (4) [M+ꢀꢁCH3],
308 (8), 279 (5), 250 (36), 151 (10), 150 (100) [O2N-
C6H4-C@O], 141 (7), 140 (7), 134 (5), 120 (7), 104 (35)
[C6H4-C@O], 92 (10), 85 (13), 84 (11), 76 (16); FABMS:
m/z 365 [M++1], 349 [M+ꢁCH3]; HRFABMS: Calcd for
C15H17N4O7: 365.1097. Found: 365.1073. Anal. Calcd
for C15H16N4O7: C, 49.45; H, 4.43; N, 15.38. Found:
C, 49.42; H, 4.34; N, 15.26.
oil, that contained traces of diisopropyl hydrazodicarb-
20
D
oxylate. ½aŠ ꢁ106.1 (c 0.97, CHCl3); 1H NMR
(500 MHz): d 3.47 (s, 3H, OCH3), 3.71 (d, 1H, H-5endo),
3.81 (d, 1H, H-3), 3.84 (dd, 1H, H-5exo), 4.25 (d, 1H, H-
2), 4.59 (d, 1H, H-4), 4.91 (s, 1H, H-1). J2,3 2.3, J4,5-exo
1.1, J5-endo,5-exo 8.4 Hz; 13C NMR (126 MHz): d 56.3
(OCH3), 61.8 (C-3), 72.1 (C-5), 77.38 (C-2 or C-4),
77.43 (C-2 or C-4), 106.1 (C-1); EIMS: m/z (%) 116
(14), 112 (9), 98 (4), 87 (22), 83 (42), 73 (24), 69 (100),
58 (58), 54 (72), 45 (95).
3.11. Preparation of 5,6-anhydro-1,2-O-isopropylidene-a-
D-glucofuranose (21)
3.10. 5-Azido-5-deoxy-1,2-O-isopropylidene-3-O-(4-
nitrobenzoyl)-a-D-xylofuranose (19)
The reaction was carried out under N2. Diisopropyl azo-
dicarboxylate (1.1 mL, 5.56 mmol) and subsequently 20
(0.63 g, 2.86 mmol) were added to a solution of triphe-
nylphosphine (1.49 g, 5.68 mmol) in dry pyridine
(16 mL). After 90 min at 90 °C the solvent was evapo-
rated, and the residue was filtered twice through silica
gel (50 g each, EtOAc; Rf 0.68) to yield 21 (0.25 g,
3.10.1. 5-Azido-5-deoxy-1,2-O-isopropylidene-a-D-xylo-
furanose (18). A solution of 17,4 (2.73 g, 15.9 mmol),
NaN3 (2.73 g, 42.0 mmol) and NH4Cl (2.24 g,
41.9 mmol) in EtOH (22 mL) and water (14 mL) was re-
fluxed for 230 h. After evaporation of the solvent EtOAc
was added. After filtration, the residue was purified by
chromatography (200 g silica gel, 1:1 EtOAc–petroleum
ether 1:1, Rf 0.51) to yield 18 (2.76 g, 12.8 mmol, 81%) as
a yellow oil that was benzoylated in the next step with-
out further purification. IR: m 3396 (OH), 2104
1.23 mmol, 43%) as a colourless solid: mp 132 °C
20
(EtOAc–petroleum ether), lit. mp 131 °C16. ½aŠ ꢁ26.2
D
(c 1.0, CHCl3); 1H NMR (500 MHz): d 1.32 (s, 3H,
CH3), 1.48 (s, 3H, CH3), 2.87 (dd, 1H, H-6), 2.99 (dd,
1H, H-60), 3.28 (s, 1H, OH), 3.41 (ddd, 1H, H-5), 4.02
(dd, 1H, H-4), 4.27 (d, 1H, H-3), 4.52 (d, 1H, H-2),
5.98 (d, 1H, H-1). J1,2 3.7, J3,4 2.5, J4,5 4.8, J5,6 2.8,
1
(N3) cmꢁ1; H NMR (400 MHz): d 1.32 (s, 3H, Me),
1.50 (s, 3H, Me0), 3.54 (d, 1H, OH), 3.58 (virtual d,
2H, H-5, H-50), 4.22 (dd, 1H, H-3), 4.28 (virtual dt,
1H, H-4), 4.54 (d, 1H, H-2), 5.95 (d, 1H, H-1). J1,2
J5,6 4.5, J6,6 4.7 Hz; 13C NMR (101 MHz): d 26.1
(CH3), 26.7 (CH3), 46.1 (C-6), 50.1 (C-5), 75.1 (C-3),
79.6 (C-4), 85.1 (C-2), 105.0 (C-1), 111.9 (CMe2); EIMS:
m/z (%) 188 (7), 187 (73) [M+ꢀꢁCH3], 169 (2), 159 (2),
127 (16), 85 (15), 59 (100), 43 (82).
0
0
3.5, J3,OH 4.8, J3,4 2.9, J4,5/5 6.3 Hz; 13C NMR
0
(101 MHz): d 26.2 (Me), 26.8 (Me0), 49.3 (C-5),
74.8 (C-3), 78.9 (C-4), 85.4 (C-2), 104.9 (C-1), 111.9 (C
Me2).
Full crystallographic details, excluding structure fea-
tures, have been deposited with the Cambridge Crystal-
lographic Data Centre. These data may be obtained, on
request, from the CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK. Tel.: +44 1223 336408; fax: +44 1223
336033; e-mail deposit@ccdc.cam.ac.uk or http://
www.ccdc.cam.ac.uk. Deposition numbers CCDC
142688 (5), 142685 (19), 227215 (21).
3.10.2.
nitrobenzoyl)-a-D-xylofuranose (19).
5-Azido-5-deoxy-1,2-O-isopropylidene-3-O-(4-
concentrated
A
solution of 4-nitrobenzoyl chloride (1.50 g. 8.1 mmol)
in dry pyridine was added to a cooled (ꢁ18 °C) solution
of 18 (1.43 g, 6.6 mmol) in dry pyridine (40 mL). After
3 h the reaction mixture was poured onto ice (300 g)
and extracted with CHCl3 (4 · 80 mL each). After dry-

O. Schulze et al. / Carbohydrate Research 340 (2005) 587–595
595
7. Wirsching, J.; Schulze, O.; Voss, J.; Giesler, A.; Kopf, J.;
Adiwidjaja, G.; Balzarini, J.; De Clercq, E. Nucleos.
Nucleot. Nucl. 2002, 21, 257–274.
8. Buchanan, J. G. Methods Carbohydr. Chem. 1972, 6, 135–
141.
Acknowledgements
We thank the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie for their financial
support. O.S. thanks the Universita¨t Hamburg for a
Graduate Scholarship.
9. Kroutil, J.; Trnka, T.; Budesinsky, M.; Cerny, M. Collect.
Czech. Chem. Commun. 1998, 63, 813–825.
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dron Lett. 1977, 50, 4383–4384; (b) Unger, F. M.;
Christian, R.; Waldsta¨tten, P. Carbohydr. Res. 1979, 69,
71–77.
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