Studies into the preparation of 1-deoxy-1-thiocyanato-D-glycopyranosyl cyanides and the anomeric effect of the thiocyanate group

Article abstract of DOI:10.1016/S0957-4166(01)00112-4

The reaction of per-O-acetylated 1-bromo-1-deoxy-α-D-arabinopyranosyl cyanide with thiocyanate ions gave the corresponding 1-deoxy-1-thiocyanato-α- and β-D-arabinopyranosyl cyanides. In the reaction of the per-O-acetylated 1-bromo-1-deoxy-β-D-xylopyranosy

Full text of DOI:10.1016/S0957-4166(01)00112-4

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 12 (2001) 731–736
Studies into the preparation of
1-deoxy-1-thiocyanato- -glycopyranosyl cyanides and the
D
anomeric effect of the thiocyanate group†
La´szlo´ Somsa´k,a,* Katalin Czifra´k,a Tama´s Deim,a La´szlo´ Szila´gyia and Attila Be´nyeib
aDepartment of Organic Chemistry, University of Debrecen, POB 20, H-4010 Debrecen, Hungary
bDepartment of Physical Chemistry, Laboratory for X-ray Diffraction, University of Debrecen, POB 7,
H-4010 Debrecen, Hungary
Received 18 January 2001; accepted 6 March 2001
Abstract—The reaction of per-O-acetylated 1-bromo-1-deoxy-a-
corresponding 1-deoxy-1-thiocyanato-a- and b- -arabinopyranosyl cyanides. In the reaction of the per-O-acetylated 1-bromo-1-
deoxy-b- -xylopyranosyl cyanide and its per-O-benzoylated b- -glucopyranosyl analogue the corresponding 2-hydroxy-glycal
esters formed in addition to the anomeric pair of thiocyanato-cyanides. The formation of 2,3,4,6-tetra-O-benzoyl-a- -glucopyra-
nosyl thiocyanate was demonstrated in the reaction of benzobromoglucose with thiocyanate ions. The equilibrium constant
between 2,3,4,6-tetra-O-acetyl-1-deoxy-1-thiocyanato-a- and b- -galactopyranosyl cyanides was determined. Based on this value,
the equilibrium ratio for the 2,3,4,6-tetra-O-acetyl-a- and b- -galactopyranosyl thiocyanates was calculated to be 94:6, and the
D-arabinopyranosyl cyanide with thiocyanate ions gave the
D
D
D
D
D
D
anomeric effect of the SCN group was estimated to exceed 3 kcal/mol. X-Ray crystallographic data support endo- and
exo-anomeric effects of the SCN moiety. © 2001 Elsevier Science Ltd. All rights reserved.
1. Introduction
b-D-glycosyl thiocyanates are formed with the potas-
sium salt.9,10 The formation of the anomeric pair of
thiocyanates 2 and 3, from which 3 was shown to be
the thermodynamically more stable product in an equi-
libration experiment,8 had no reported precedent or
As part of an ongoing project directed towards the
application of anomerically bifunctional monosaccha-
ride derivatives1,2 to the synthesis of glycosylidene-
spiro-heterocycles3,4 related to (+)-hydantocidin and
inhibitors of glycogen phosphorylase enzymes,5–7 we
recently reported the preparation of galactopyranosyl-
idene-spiro-thiazolines and -thiazolidines.8 These
bicyclic compounds were obtained by treatment of 1-
analogy in the
D-glycopyranosyl bromide series. Pursu-
ing these observations we extended the reaction to
other sugars and re-examined the formation of
copyranosyl thiocyanates and isothiocyanates.
D-glu-
deoxy-1-thiocyanato-
D
-galactopyranosyl cyanides 2 and
3 with hydrogen sulfide. The starting materials 2 and 3
2. Results and discussion
were prepared from 1-bromo-1-deoxy-b-D-galactopyra-
nosyl cyanide 1 using silver or potassium thiocyanate.8
In this reaction, formation of thiocyanates was
observed regardless of the cation present. This finding
Per-O-acylated 1-bromo-1-deoxy-glycopyranosyl cyan-
ides with a-
-arabino11 8, b- -gluco7 11, and b- -xylo11
D
D
D
12 configurations were reacted with 2 equiv. of potas-
sium thiocyanate in nitromethane at 90°C. From the
reaction of 8 the anomeric pair 9 and 10 could be
isolated and no by-products were detected. In contrast,
11 and 12 gave the 1-cyano-2-hydroxy-glycal esters 20
and the known 21,12 in addition to the expected pairs of
14 and 17 and 15 and 18. Compounds 9 and 10 were
separated by column chromatography but, despite
much effort, only 17, 20, and 21 could be obtained in
pure form from the other products.
contrasts with the literature reports on acetylated D-gly-
copyranosyl bromides, which are known to give b-D-
glycosyl isothiocyanates with silver thiocyanate, whilst
* Corresponding author. Fax: +36-52-453-836; e-mail: somsak@
tigris.klte.hu
†
Dedicated to Professor Ge´rard Descotes in appreciation of his
outstanding achievements in carbohydrate chemistry.
0957-4166/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(01)00112-4

732
L. Somsa´k et al. / Tetrahedron: Asymmetry 12 (2001) 731–736
Figure 1. Composition of the reaction mixture of 2,3,4,6-
tetra-O-benzoyl-1-bromo-1-deoxy-b- -glucopyranosyl cyan-
Figure 2. Composition of the reaction mixture of 2,3,4,6-
tetra-O-benzoyl-a- -glucopyranosyl bromide 13 with 3 equiv.
of KSCN in the presence of 0.2 equiv. of 18-crown-6 in
acetone at rt.
D
D
ide 11 with 2 equiv. of KSCN in nitromethane at 90°C.
The elimination products 20 and 21 formed only in the
ence of 18-crown-6 proved to be advantageous.14 The
corresponding isothiocyanates were obtained with silver
thiocyanate in benzene or toluene,15 or under the afore-
mentioned conditions after prolonged reaction time,14
as well as by several other modifications of the original
protocol.16–19 In these reports neither anomerisation of
the kinetically formed 1,2-trans glycosyl thiocyanates
nor competing eliminations were mentioned. In order
reactions of the
materials, respectively. Similarly, in accord with earlier
observations in the preparation of 1-deoxy-1-fluoro-
glycopyranosyl cyanides,2 the appearance of elimina-
tion products only in the -gluco and -xylo
configurations can be explained by the sterically
crowded position of the C-(2) proton in the -arabino
and the -galacto compounds. In these derivatives the
D-gluco and D-xylo configured starting
D
-
D
D
D
D
to
study
these
aspects
of
the
reaction,
axially oriented 4-acetoxy group hinders the approach
of the base/nucleophile to the axial C-(2)H. This proton
is prone to elimination if the 4-acetoxy group is equat-
orial. A deeper insight into the formation of the D-gluco
derivatives 14, 17, and 20 can be obtained from Fig. 1.
benzobromoglucose20 13 was subjected to treatment
with KSCN–18-crown-6.21 As expected, the corre-
sponding thiocyanate 16 and isothiocyanate 23 could be
isolated by column chromatography after relatively
short and long reaction times, respectively. However,
we also obtained fractions which were chromatographi-
cally homogeneous, but their NMR spectrum showed
the presence of two compounds. Unfortunately, we
were unable to find suitable chromatographic condi-
tions for their separation. From the proton spectrum it
It can be seen that formation of the elimination product
20 continued after the starting material 11 was com-
pletely consumed. This suggests that 20 can form not
only from 11 but also from either of the anomers 14 or
17, most probably from the latter in which the trans-
diaxial arrangement of C-(2)H and the SCN group
fulfils the stereoelectronic requirement for b-elimina-
tion. It also follows from this that, contrary to the
was clear that an a-
D- (l 6.49 ppm, J1,2=5.5 Hz) and a
-glucopyranosyl (l 5.36 ppm, J1,2=8.8 Hz) deriva-
b-D
tive were present in the sample. The 13C spectrum
showed resonances for both a thiocyanate (l 108.3
ppm) and an isothiocyanate (l 144.6 ppm) group. A
13C–1H HMBC measurement indicated unambiguously
D
-galacto anomers 2 and 3, equilibration between 14
and 17 is not possible.
that the mixture contained the a-
D-glucopyranosyl thio-
-glucopyranosyl isothiocyanate
Structural elucidation of the new compounds was
cyanate 19 and the b-
D
accomplished by NMR methods. Compounds 9 and 10
1
23. Monitoring the reaction (Fig. 2) showed that 19 was
present in the mixture in significant amounts.
(
D
-arabino) have the C4 conformation, while 14 and 17
4
(
D
-gluco) and 15 and 18 (D-xylo) exist in the C1 form
as depicted. The 13C NMR spectra indicated the pres-
ence of both the cyano (111.4–113.6 ppm) and the
thiocyanato (104.7–108.4 ppm) moieties. In the given
conformations the configurations of the anomeric car-
Subjecting the b- -glucopyranosyl thiocyanate 16 to
D
the same reaction conditions (Fig. 3) revealed that 19
may be an intermediate in the isomerisation of 16 to 23.
However, this is probably not the only pathway to 23
from 13, because the isothiocyanate 23 appears earlier
than 19 in that reaction (Fig. 2). No traces of the
possible elimination product 22 could be detected in
these mixtures. These experiments showed that direct
equilibration of 16 and 19 was not possible because of
the formation of the more stable 23. Since under the
same conditions glycopyranosyl isothiocyanates can be
made in many sugar configurations, it can be concluded
3
bons were assigned on the basis of the JH-2,CN het-
eronuclear couplings showing 6.6–8.1 Hz values for
trans-diaxial arrangements and 2.1–3.5 Hz for gauche
relationships.1
Since each reaction described above gave anomeric
pairs of the thiocyanato-cyanides and products of elim-
ination in some cases it seemed pertinent to examine
more
closely
the
formation
of
glycosyl
that the equilibrium between a- and b-D-glycopyranosyl
thiocyanates cannot be observed and determined
directly.
(iso)thiocyanates. Glycosyl thiocyanates were prepared,
for example, from acylated glycopyranosyl bromides
with potassium thiocyanate in acetone,13 and the pres-

L. Somsa´k et al. / Tetrahedron: Asymmetry 12 (2001) 731–736
733
were averaged for the calculation of K1. The calculated
value of K3 indicates that the SCN group has a strong
axial preference at the anomeric centre. Consequently,
this group has a considerable anomeric effect (AE). An
estimation of its numerical value23 (AESCN=RT ln K3+
ASCN) can be made by taking into account the confor-
mational energy (A) of the SCN moiety in cyclohexyl
thiocyanate24 (ASCN=1.23 kcal/mol, determined at
−79°C in CS2–TMS 9:1) as modified to the correspond-
ing tetrahydropyran-2-yl thiocyanate according to
Franck’s proposal25 (1.92 kcal/mol). Thus the anomeric
effect of the SCN group must be larger than 3 kcal/mol
Figure 3. Composition of the reaction mixture of 2,3,4,6-
tetra-O-benzoyl-b- -glucopyranosyl thiocyanate 16 with 3
in the
D
-galacto configured pair of 6 and 7.
D
equiv. of KSCN in the presence of 0.2 equiv. of 18-crown-6 in
acetone at rt.
An X-ray crystallographic structure determination of 3
(Fig. 4) indicated dihedral angle of 51° for
a
O1ꢀC1ꢀS1ꢀC8, which reveals the operation of an exo-
anomeric effect with respect to the SCN group (the
same parameter in 2 was found8 to be −72°). The bond
lengths and angles around the anomeric centre of 2 and
3 (Fig. 4) are also consistent with the operation of these
anomeric effects.23
An indirect possibility to establish the above type equi-
librium is offered by the equilibrated mixture of 2 and
3, where no by-products were detected. Considering the
known equilibrium ratio of the anomeric pair of the
corresponding glycosyl cyanides 4 and 522 (K2=0.0705)
allows the ratio for 6 and 7 to be calculated. To this
end, 2 and 3 were equilibrated to obtain K1 under
conditions used for the determination of K2 (Scheme 1).
Compound 2 was incubated at 40°C in carbon tetra-
chloride with either 1 or 6 equivalents of tetra-
butylammonium thiocyanate. Equilibrium was reached
after 25 days in the first case and after 6 days in the
second. The anomeric ratios obtained from the proton
NMR spectra were 47:53 and 45:55, respectively, which
3. Conclusion
In conclusion, the study of the reaction of several
1-bromo-1-deoxy-
cyanate ion showed that anomeric pairs of 1-deoxy-1-
thiocyanato- -glycopyranosyl cyanides can be prepared
and separated in the -arabino (and the
-galacto8)
D-glycopyranosyl cyanides with thio-
D
D
D
Scheme 1. (a) Bu4NSCN, CCl4, 40°C; (b) KSCN, CH3NO2, 90°C; (c) KSCN, 18-crown-6, acetone, rt.

734
L. Somsa´k et al. / Tetrahedron: Asymmetry 12 (2001) 731–736
,
D-galactopyranosyl cyanide 3 and bond lengths (A)
Figure 4. ORTEP drawing of 2,3,4,6-tetra-O-acetyl-1-deoxy-1-thiocyanato-b-
and angles in 2 and 3.
configuration, while elimination products accompany
the anomers in the -gluco and -xylo configura-
-glu-
copyranosyl thiocyanate was demonstrated in the
reaction of benzobromoglucose with thiocyanate ion.
4.1. General procedure for the reaction of acetylated
1-bromo-1-deoxy- -glycopyranosyl cyanides 8, 11, and
12 with thiocyanate ion
D
D
D
tions. The presence of per-O-benzoylated a-
D
1-Bromo-1-deoxy-D-glycopyranosyl cyanide (1 mmol)
The equilibration of 1-deoxy-1-thiocyanato-
topyranosyl cyanides allowed the anomeric ratio for
the a- and b- -galactopyranosyl thiocyanates to be
D
-galac-
was dissolved in nitromethane (14 mL) and dry potas-
sium thiocyanate (0.194 g, 2 mmol) was added. The
mixture was stirred at 90°C (bath temp.) until complete
disappearance of the starting material (TLC ethyl
acetate–hexane 2:1, 5–7 h). The mixture was then
filtered and the solvent removed from the filtrate. The
residue was dissolved in chloroform, washed with water,
dried, the solvent evaporated, and the syrupy crude
product purified by column chromatography (eluent
ethyl acetate–hexane 1:2 or 1:3).
D
calculated and, thereby, the anomeric effect of the
SCN group to be estimated. X-Ray crystallography
revealed the operation of an exo-anomeric effect in
both isomers.
4. Experimental
Melting points were measured in open capillary tubes
or on a Kofler hot-stage and are uncorrected. Optical
rotations were determined with a Perkin–Elmer 241
polarimeter at room temperature. NMR spectra were
recorded with Bruker WP 200 SY (200/50 MHz for
1H/13C) or Avance DRX 500 (500/125 MHz for
1H/13C) spectrometers for CDCl3 solutions unless oth-
erwise stated. Chemical shifts are referenced to Me4Si
(1H) or to the residual solvent signals (13C). TLC was
performed on DC-Alurolle Kieselgel 60 F254 (Merck),
and the plates were visualised after gentle heating.
For column chromatography Kieselgel 60 (Merck,
particle size 0.063–0.200 mm) was used. Organic solu-
tions were dried over anhydrous MgSO4 and concen-
trated in vacuo at 40–50°C (water bath).
Nitromethane was distilled from P4O10 directly in the
4.2. 2,3,4-Tri-O-acetyl-1-deoxy-1-thiocyanato-b-D-ara-
binopyranosyl cyanide 9
Yield 23%; mp 91–92°C (from EtOH); [h]D=−237 (c
1
1.02, CHCl3); wSCN (KBr): 2158 cm−1; H NMR: l 5.50
(1H, d, J=9.5 Hz, H-2), 5.46–5.40 (1H, m, H-4), 5.27
(1H, dd, J=9.5, 3.2 Hz, H-3), 4.28 (1H, dd, J=13.6,
3.7 Hz, H-5), 4.17 (1H, dd, J=13.6, 1.5 Hz, H-5%); 13C
3
NMR: l 111.4 (CN, JH-2,CN=7.2 Hz), 105.2 (SCN),
83.6 (C-1), 68.5, 67.9, 66.3 (C-2 to C-4), 67.7 (C-5).
Anal. calcd for C13H14N2O7S (342.32): C, 45.61; H,
4.12; N, 8.18. Found: C, 45.34; H, 4.18; N, 8.15%.
4.3. 2,3,4-Tri-O-acetyl-1-deoxy-1-thiocyanato-a-D-ara-
binopyranosyl cyanide 10
,
reaction flask or was stored over 3 A molecular
Yield 19%; mp 151–153°C (from EtOH); [h]D=−115
1
sieves. Monitoring of the reactions was performed by
taking aliquot samples from the reaction mixtures
which were investigated by 1H NMR after work-up.
(c 1.02, CHCl3); wSCN (KBr): 2168 cm−1; H NMR: l
5.87 (1H, d, J=9.5 Hz, H-2), 5.45–5.40 (1H, m, H-4),
5.14 (1H, dd, J=9.4, 2.8 Hz, H-3), 4.22–4.15 (2H, m,

L. Somsa´k et al. / Tetrahedron: Asymmetry 12 (2001) 731–736
735
H-5,5%); 13C NMR: l 113.6 (CN, 3JH-2,CN=2.1 Hz),
105.3 (SCN), 85.6 (C-1), 67.5, 67.1, 66.3 (C-2 to C-4),
65.1 (C-5). Anal. calcd for C13H14N2O7S (342.32): C,
45.61; H, 4.12; N, 8.18. Found: C, 45.40; H, 4.20; N,
8.16%.
110.4 (CN), 125.5 (C-2), 137.9 (C-3), 75.7, 67.2, 65.8
(C-4 to C-6), 60.5 (C-7). Anal. calcd for C35H25N2O9
(603.58): C, 69.65; H, 4.17; N, 2.32. Found: C, 69.87;
H, 3.92; N, 2.44%.
4.9. Reaction of 2,3,4,6-tetra-O-benzoyl-a-D-gluco-
4.4. 2,3,4,6-Tetra-O-benzoyl-1-deoxy-1-thiocyanato-a-
D
-
pyranosyl bromide 13 with thiocyanate ion14,21
glucopyranosyl cyanide 14
Benzobromoglucose (13, 1 g, 3 mmol) was dissolved in
dry acetone, then potassium thiocyanate (0.705 g, ꢀ9
mmol) and 18-crown-6 (0.072 g, 0.2 mmol) were added.
The mixture was stirred at room temp. and monitored
by 1H NMR. Work-up of the reaction mixture after 9 h
and chromatography of the crude product (eluent: ethyl
acetate–hexane 1:2) gave the products below.
Could not be isolated in a pure state. Yield 46% for a
1
mixture of 14+20; H NMR: l 6.18 (1H, t, J=9.5 Hz,
H-3), 5.88 (1H, t, J=9.5, 8.4 Hz, H-4), 5.84 (1H, d,
J=9.5 Hz, H-2), 4.75–4.70 (3H, m, H-5,6,6%); 13C
3
NMR: l 111.5 (CN, JH-2,CN=2.8 Hz), 104.9 (SCN),
82.9 (C-1), 76.8, 71.3, 71.1, 67.3 (C-2 to C-5), 61.6
(C-6).
4.10. 2,3,4,6-Tetra-O-benzoyl-b-D-glucopyranosylthio-
4.5. 2,3,4,6-Tetra-O-benzoyl-1-deoxy-1-thiocyanato-b-
D
-
cyanate 16
glucopyranosyl cyanide 17
Yield 22%, colourless syrup; [h]D=+16 (c 1.01, CHCl3),
1
Yield 7%; mp 197–199°C (from EtOH); [h]D=+123 (c
lit.21 [h]D +46 (c 0.80, CHCl3); H NMR (the spectrum
1.01, CHCl3); wSCN (KBr): 2160 cm−1; H NMR: l 6.31
obtained is different from the reported one21): l 6.00
(1H, pseudo t, J=9.9, 9.5 Hz, H-2), 5.77 (1H, t, J=9.5
Hz, H-4), 5.67 (1H, t, J=9.5 Hz, H-3), 5.27 (1H, d,
J=9.9 Hz, H-1), 4.66 (1H, dd, J=12.6, 2.6 Hz, H-6),
4.52 (1H, dd, J=12.6, 5.3 Hz, H-6%), 4.33 (1H, ddd,
J=9.5, 6.3, 2.6 Hz, H-5); 13C NMR (corresponds to the
reported spectrum21): l 108.4 (SCN), 83.9 (C-1), 73.2,
71.2, 68.6, 62.6 (C-2 to C-5), 60.3 (C-6).
1
(1H, d, J=9.5 Hz, H-2), 5.97 (1H, t, J=9.5 Hz, H-3),
5.84 (1H, t, J=9.9, 9.5 Hz, H-4), 4.81 (1H, ddd, J=9.9,
5.6, 2.1 Hz, H-5), 4.73 (1H, dd, J=12.8, 5.6 Hz, H-6),
4.60 (1H, dd, J=12.8, 2.1 Hz, H-6%); 13C NMR: l 113.5
3
(CN, JH-2,CN=8.1 Hz), 104.7 (SCN), 85.2 (C-1), 73.6,
71.0, 70.0, 67.2 (C-2 to C-5), 61.8 (C-6). Anal. calcd for
C36H26N2O9S (662.67): C, 65.25; H, 3.95; N, 4.23.
Found: C, 64.58; H, 3.96; N, 4.30%.
4.11. 2,3,4,6-Tetra-O-benzoyl-a-D-glucopyranosylthio-
4.6. 2,3,4-Tri-O-acetyl-1-deoxy-1-thiocyanato-a-
D
-
cyanate 19
xylopyranosyl cyanide 15
Could not be completely purified. Yield 17% for a
1
Could not be isolated in pure state. Yield 45% for a
mixture of 19+23; H NMR: l 6.49 (1H, d, J=5.5 Hz,
1
mixture of 15+18; H NMR (assignments deduced from
H-1), 5.82 (1H, dd, J=9.6, 5.5 Hz, H-2), 5.62 (1H, t,
J=9.6 Hz, H-4), 5.56 (1H, t, J=9.6 Hz, H-3), 4.71 (1H,
ddd, J=9.6, 6.3, 3.1 Hz, H-5), 4.58 (1H, dd, J=12.6,
3.1 Hz, H-6), 4.48 (1H, dd, J=12.6, 6.3 Hz, H-6%); 13C
NMR (CDCl3): l 108.3 (SCN), 86.1 (C-1), 71.4, 70.5,
69.9, 68.0 (C-2 to C-5), 62.2 (C-6).
COSY experiments): l 5.37 (1H, t, J=8.5 Hz, H-3),
5.22 (1H, d, J=8.5 Hz, H-2), 5.06 (1H, ddd, J=9.8,
8.5, 5.2 Hz, H-4), 4.40 (1H, dd, J=12.3, 5.2, H-5), 3.83
(1H, dd, J=12.1, 9.8 Hz, H-5%); 13C NMR: l 113.4
3
(CN, JH-2,CN=6.6 Hz), 105.1 (SCN), 83.2 (C-1), 69.9,
68.7, 66.5 (C-2 to C-4), 65.4 (C-5).
4.12. 2,3,4,6-Tetra-O-benzoyl-b-D-glucopyranosyliso-
thiocyanate 23
4.7. 2,3,4-Tri-O-acetyl-1-deoxy-1-thiocyanato-b-
xylopyranosyl cyanide 18
D
-
Yield 33%; mp 149–151°C, lit.10 mp 147–148°C; 1H
NMR: l 5.94 (1H, t, J=9.5, 8.8 Hz, H-2), 5.75 (1H, t,
J=9.5 Hz, H-3), 5.66 (1H, t, J=9.5 Hz, H-4), 5.36 (1H,
d, J=8.8 Hz, H-1), 4.68 (1H, dd, J=12.2, 2.0 Hz, H-6
or H-6%), 4.45 (1H, dd, J=12.2, 4.7 Hz, H-6 or H-6%),
4.24 (1H, ddd, J=9.5, 4.7, 2.0 Hz, H-5); 13C NMR: l
144.6 (NCS), 83.8 (C-1), 74.4, 72.6, 72.3, 68.8 (C-2 to
C-5), 62.5 (C-6).
Could not be isolated in pure state. Yield 45% for a
mixture of 15+18; H NMR (assignments deduced from
1
COSY experiments): l 5.62 (1H, d, J=8.8 Hz, H-2),
5.27 (1H, t, J=8.5 Hz, H-3), 5.12 (1H, ddd, J=9.8, 8.5,
5.5 Hz, H-4), 4.35 (1H, dd, J=12.1, 5.4 Hz, H-5), 3.92
(1H, dd, J=12.1 9.8 Hz, H-5%); 13C NMR: l 111.4 (CN,
3JH-2,CN=3.5 Hz), 105.1 (SCN), 84.8 (C-1), 70.1, 68.2,
66.5 (C-2 to C-4), 63.0 (C-5).
4.13. X-Ray crystallography of 3
4.8. 2,6-Anhydro-3,4,5,7-tetra-O-benzoyl- -arabino-hex-
D
2-enononitrile 20
Colourless block crystals (0.45×0.25×0.16 mm) of
C16H18N2O9S, M=414.38, monoclinic, a=11.094(2) A,
,
,
,
Yield 5%; mp 108–110°C (from EtOH); [h]D=+60 (c
1.03, CHCl3); 1H NMR: l 6.27 (1H, d, J=4.2 Hz,
H-4), 5.91 (1H t, J=4.8, 4.8 Hz, H-5), 5.01 (1H, ddd,
J=6.8, 4.8, 4.2 Hz, H-6), 4.91 (1H, dd, J=12.2, 4.2 Hz,
H-7), 4.73 (1H, dd, J=12.2, 6.8 Hz, H-7%); 13C NMR: l
b=7.9141(10) A, c=22.678(3) A, i=97.34(1)°, V=
1974.4(5) A , Z=4, space group: P21, zcalcd=1.394
3
,
g/cm3. Data were collected at 293(1) K, Enraf Nonius
MACH3 diffractometer, Mo Ka radiation u=0.71073
A, ꢀ−2q motion, qmax=26°, 4161 measured, 2112
,

736
L. Somsa´k et al. / Tetrahedron: Asymmetry 12 (2001) 731–736
9. Witczak, Z. J. Adv. Carbohydr. Chem. Biochem. 1986, 44,
91–145.
10. Fernandez, J. M. G.; Mellet, C. O. Sulfur Rep. 1996, 19,
61–169.
11. Somsa´k, L.; Batta, G.; Farkas, I. Carbohydr. Res. 1983,
124, 43–51.
12. Somsa´k, L.; Papp, E.; Batta, G.; Farkas, I. Carbohydr.
Res. 1991, 211, 173–178.
reflections were unique with I>2|(I), decay: 3%. The
structure was solved using the SIR-92 software26 and
refined on F2 using the SHELX-9727 program, publica-
tion material was prepared with the WINGX-97 suite,28
R(F)=0.081 and wR(F2)=0.1767 for 4161 reflections,
505 parameters. Residual electron density: 0.286/−0.285
3
,
e/A .
13. Mueller, A.; Wilhelms, A. Ber. d. D. Chem. Gesellschaft
1941, 74, 698–705.
Acknowledgements
14. Kochetkov, N. K.; Klimov, E. M.; Malysheva, N. N.;
Demchenko, A. V. Carbohydr. Res. 1991, 212, 77–91.
15. Ogura, H.; Takahashi, H. Heterocycles 1982, 17, 87–90.
16. Camarasa, M. J.; Ferna´ndez-Resa, P.; Garcia-Lopez, M.
T.; De Las Heras, F. G.; Mendez-Castrillon, P. P.; San-
Fe´lix, A. Synthesis 1984, 509–510.
Financial support was received from the Hungarian
Scientific Research Fund (Grant: OTKA T32124) and
the Ministry of Education (Grant: FKFP 500/1997).
Dr. K. E. Ko¨ve´r is thanked for carrying out the HBMC
measurement.
17. Yamamoto, I.; Fukui, K.-I.; Yamamoto, S.; Ohta, K.;
Matsuzaki, K. Synthesis 1985, 686–688.
18. Taspulatov, A. A.; Rahmatullaev, I.; Afanasev, V. A.;
Ismailov, N. Zh. Org. Khim. 1988, 24, 1893–1897.
19. Lindhorst, T. K.; Kieburg, C. Synthesis 1995, 1228–1230.
20. Lockhoff, O. In Methoden der organischen Chemie
(Houben-Weyl); Hagemann, H.; Klamann, D., Eds.;
Thieme: Stuttgart, 1992; Vol. E14a/3, p. 708.
21. Pakulski, Z.; Pierozynski, D.; Zamojski, A. Tetrahedron
1994, 50, 2975–2992.
22. Somsa´k, L.; Szabo´, M. J. Carbohydr. Chem. 1990, 9,
755–759.
23. Tvarosˇka, I.; Bleha, T. Adv. Carbohydr. Chem. Biochem.
1989, 47, 45–123.
24. Jensen, F. R.; Bushweller, C. H.; Beck, B. H. J. Am.
Chem. Soc. 1969, 91, 344–351.
References
1. Somsa´k, L.; So´s, E.; Gyo¨rgydea´k, Z.; Praly, J.-P.;
Descotes, G. Tetrahedron 1996, 52, 9121–9136.
2. Gyo´llai, V.; Somsa´k, L.; Gyo¨rgydea´k, Z. Tetrahedron
1998, 54, 13267–13276.
3. Osz, E.; So´s, E.; Somsa´k, L.; Szila´gyi, L.; Dinya, Z.
Tetrahedron 1997, 53, 5813–5824.
4. Somsa´k, L.; Kova´cs, L.; Gyo´llai, V.; Osz, E. Chem.
2
2
Commun. 1999, 591–592.
5. Osz, E.; Somsa´k, L.; Szila´gyi, L.; Kova´cs, L.; Docsa, T.;
2
To´th, B.; Gergely, P. Bioorg. Med. Chem. Lett. 1999, 9,
1385–1390.
6. Somsa´k, L.; Nagy, V.; Docsa, T.; To´th, B.; Gergely, P.
Tetrahedron: Asymmetry 2000, 11, 405–408.
7. Somsa´k, L.; Nagy, V. Tetrahedron: Asymmetry 2000, 11,
1719–1727; Corrigendum 2247.
25. Franck, R. W. Tetrahedron 1983, 39, 3251–3252.
26. Altomare, A.; Cascarano, G.; Giacovazzo, C.;
Guagliardi, A. J. Appl. Cryst. 1993, 26, 343–350.
27. Sheldrick, G. M. SHELXL-97, Universita¨t Go¨ttingen,
Germany.
2
8. Osz, E.; Szila´gyi, L.; Somsa´k, L.; Be´nyei, A. Tetrahedron
28. Farrugia, L. J. WINGX-97 system, University of Glas-
gow, UK.
1999, 55, 2419–2430.
.
.