Synthesis and structure determination of some nonanomerically C-C-linked serine glycoconjugates structurally related to mannojirimycin

Article abstract of DOI:10.1016/j.carres.2004.06.020

The Bucherer-Bergs reaction of methyl 2,3-O-isopropylidene-α-D-lyxo- hexofuranosid-5-ulose gave (4′S)-4′-carbamoyl-4′-[methyl (4R)-2,3-O-isopropylidene-β-L-erythrofuranosid-4-C-yl]-oxazolidin-2′- one instead of expected hydantoins. A mixture of hydantoins - (5′R)-triphenylmethoxymethyl-5′-[methyl (4R)-2,3-O-isopropylidene- β-l-erythrofuranosid-4-C-yl]-imidazolidin-2′,4′-dione and (5′S)-triphenylmethoxymethyl-5′-[methyl (4R)-2,3-O-isopropylidene- β-L-erythrofuranosid-4-C-yl]-imidazolidin-2′,4′-dione was obtained from the 5-ulose having protected primary OH group at C-6. The 4′-S configuration of 2 as well as 5′-S configuration of (5′S)-hydroxymethyl-5′-[methyl (4R)-2,3-O-isopropylidene-β-L- erythrofuranosid-4-C-yl]-imidazolidin-2′,4′-dione (9) was confirmed by X-ray crystallography. Corresponding α-amino acid-methyl (5S)-5-amino-5-C-carboxy-5-deoxy-α-D-lyxo-hexofuranoside (alternative name: 2-[methyl (4R)-β-L-erythrofuranosid-4-C-yl]-L-serine) (11) was obtained from the hydantoin 9 by acid hydrolysis of the isopropylidene and trityl groups followed by basic hydrolysis of the hydantoin ring. Analogous derivatives with 5-R configuration, formed in a minority, were also isolated and characterised.

Full text of DOI:10.1016/j.carres.2004.06.020

Carbohydrate
RESEARCH
Carbohydrate Research 339 (2004) 2187–2195
Synthesis and structure determination of some
nonanomerically C–C-linked serine glycoconjugates
structurally related to mannojirimycin
a
Ju´lia Micova, Bohumil Steiner, Miroslav Koos, Vratislav Langer and
a
b
´ˇ a,
*
ˇ
´
c
´
Dalma Gyepesova
a
´
´
Institute of Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, SK-84538 Bratislava, Slovakia
bDepartment of Inorganic Environmental Chemistry, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
c
´ ´
Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dubravska cesta 9, SK-84536 Bratislava, Slovakia
Received 2 March 2004; received in revised form 25 May 2004; accepted 26 June 2004
Available online 10 August 2004
Abstract—The Bucherer–Bergs reaction of methyl 2,3-O-isopropylidene-a-D-lyxo-hexofuranosid-5-ulose gave (40S)-40-carbamoyl-
40-[methyl (4R)-2,3-O-isopropylidene-b-L-erythrofuranosid-4-C-yl]-oxazolidin-20-one instead of expected hydantoins. A mixture
of hydantoins––(50R)-triphenylmethoxymethyl-50-[methyl (4R)-2,3-O-isopropylidene-b-L-erythrofuranosid-4-C-yl]-imidazolidin-
20,40-dione and (50S)-triphenylmethoxymethyl-50-[methyl (4R)-2,3-O-isopropylidene-b-L-erythrofuranosid-4-C-yl]-imidazolidin-
20,40-dione was obtained from the 5-ulose having protected primary OH group at C-6. The 40-S configuration of 2 as well as 50-
S configuration of (50S)-hydroxymethyl-50-[methyl (4R)-2,3-O-isopropylidene-b-L-erythrofuranosid-4-C-yl]-imidazolidin-20,40-dione
(9) was confirmed by X-ray crystallography. Corresponding a-amino acid––methyl (5S)-5-amino-5-C-carboxy-5-deoxy-a-D-lyxo-
hexofuranoside (alternative name: 2-[methyl (4R)-b-L-erythrofuranosid-4-C-yl]-L-serine) (11) was obtained from the hydantoin 9
by acid hydrolysis of the isopropylidene and trityl groups followed by basic hydrolysis of the hydantoin ring. Analogous derivatives
with 5-R configuration, formed in a minority, were also isolated and characterised.
Ó 2004 Elsevier Ltd. All rights reserved.
Keywords: Sugar amino acids; Hydantoins; Serine; Bucherer–Bergs reaction; Mannojirimycin; X-ray crystallography; Conformation
1. Introduction
aim to develop new powerful glycosidase inhibitors
and effective compounds for drug design. To improve
the metabolic stability of these potential drugs, a lot of
more stable C–C-linked analogues have been synthe-
sised during the past two decades.3–21 In this respect,
a,a-disubstituted sugar a-amino acids are subjects of
exceptional interest because an additional substituent
at the a-position sterically constrains the free rotation
or conformation flexibility of their side chain or strictly
fixes conformation by a saccharide ring. Incorporation
of such sugar amino acids into a peptide imparts well-
defined conformational constraints to a peptide back-
bone preferring folded conformation, inducing a-helical
secondary structures and stabilising the neighbouring
peptide bond against chemical or enzymatic hydrolysis
due mainly to steric reasons.22,23
Sugar amino acids represent highly substituted poly-
functionalised building blocks, which can be used in
the preparation of very useful glycomimetic and pepti-
domimetic libraries. Carbohydrate moieties of glycopro-
teins and glycolipids play an important role in a variety
of biological events, especially in recognition phenom-
ena and immune response.1 Their decisive influence on
conformation, solubility and stabilisation of proteins is
also known.2 The use of synthetic glycopeptide model
compounds became attractive for understanding of the
mutual interactions between both moieties with the
*
Corresponding author. Tel.: +421-2-59410254; fax: +421-2-
59410222; e-mail: chemmiro@savba.sk
0008-6215/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2004.06.020

ˇ ´
J. Micova et al. / Carbohydrate Research 339 (2004) 2187–2195
2188
Hydrolysis of hydantoins provides a suitable route for
2. Results and discussion
the preparation of sugar a-amino acids.24–27 Although
starting hydantoins can be obtained conveniently by
the Bucherer–Bergs reaction (or its modification accord-
ing to Hoyer), only a few papers on the application of
this reaction to a carbohydrate derivative have been
reported till now.26–34 Recently, we have published31–34
the synthesis of some sugar a-amino acids via corre-
sponding hydantoin derivatives starting from methyl
6-deoxy-2,3-O-isopropylidene-a-L-lyxo-hexopyranosid-
4-ulose, methyl 6-deoxy-2,3-O-isopropylidene-a-D-lyxo-
hexofuranosid-5-ulose, methyl 6-deoxy-2,3-O-isopropy-
lidene-a-L-lyxo-hexofuranosid-5-ulose and methyl 6-de-
oxy-6-isopropyl-2,3-O-isopropylidene-a-D-lyxo-hexo-
furanosid-5-ulose. In these cases, with exception of
starting hexopyranosid-4-ulose, the prepared glycocon-
jugate model compounds have C-2-linked a-amino acid
attached to a furanoside moiety in the C-4 position,
while C-2 atom of a-amino acid coincides with C-5 atom
of sugar backbone (C-5–C-2 fused sugar a-amino acid).
In this paper we present the synthesis and structure
determination of some serine derivatives branched at
C-2 atom with a saccharide moiety, obtained from suit-
ably 6-O-protected methyl a-D-lyxo-hexofuranosid-5-
ulose. Further studies on the preparation of analogous
glycoconjugates related to phenylalanine or aspartic
acid branched with a glucose or mannose moiety,
respectively, are in progress.
According to our previously published35 results, the
Bucherer–Bergs reaction of the known methyl 2,3-O-
isopropylidene-a-D-lyxo-hexofuranosid-5-ulose (1)36–39
did not afford expected corresponding hydantoin
derivatives 4 and 5 but (40S)-40-carbamoyl-40-[methyl
(4R)-2,3-O-isopropylidene-b-L-erythrofuranosid-4-C-yl]-
oxazolidin-20-one (2) was preferentially formed via ring
closure including unprotected primary hydroxyl group
at C-6 atom of the starting 5-ulose 1 (Scheme 1). There-
fore, its initial protection is crucial to avoid such unde-
sired cyclisation and we have used O-tritylation for this
purpose. Thus, application of the Bucherer–Bergs reac-
tion to methyl 2,3-O-isopropylidene-6-O-triphenylmeth-
yl-a-D-lyxo-hexofuranosid-5-ulose (3)39 gave a mixture
of (50R)-triphenylmethoxymethyl-50-[methyl (4R)-2,3-
O-isopropylidene-b-L-erythrofuranosid-4-C-yl]-imidaz-
olidin-20,40-dione (4) and (50S)-triphenylmethoxymethyl-
50-[methyl
(4R)-2,3-O-isopropylidene-b-L-erythrofur-
anosid-4-C-yl]-imidazolidin-20,40-dione (5) (Scheme 1).
The stereoselectivity of this reaction was almost 60%
(ee, based on the analysis of NMR spectra of the reac-
tion mixture) in favour of the hydantoin 5 having S con-
figuration at C-5 (with respect to both carbohydrate and
hydantoin atoms numbering) unlike alanine and leucine
analogues32,34 (6-deoxy or 5-isobutyl derivatives) where
5-R derivatives were favoured. This can be probably
NH2
H
O
CH2OH
C
N
NH2
C
O
C
O
O
CH2OH
HOOC
HOH2C
HO
OH
NH
O
O
O
OH
HO
OH HO
OH
OCH3
OCH3
serine moiety
COOH
O
O
O
O
5-C-Carboxymannojirimycin
CH3
CH3
H3C
H3C
mannojirimycin moiety
(furanose form)
2
1
H
N
H
N
O
O
CH2OH
C
CH2OTr
O
C
O
H
O
N
HN
HN
C
C
CH2OH
H2N
C
CH2OH
CH2OTr
C
O
O
OCH3
OCH3
O
O
O
O
O
O
HN
O
OH HO
OH HO
C
HOOC
O
CH3
CH3
H3C
O
H3C
OCH3
OCH3
4
6
7
8
OCH3
O
O
O
O
C
CH3
C
H3C
CH2OH
O
CH2OTr
O
HN
HN
O
3
C
C
HOOC
H2N
C
N
H
CH2OH
N
H
O
O
CH2OH
HN
C
OCH3
OCH3
O
O
O
O
O
OH HO
O
OH HO
N
H
O
OCH3
OCH3
CH3
CH3
H3C
H3C
11
10
9
5
Scheme 1.

ˇ ´
J. Micova et al. / Carbohydrate Research 339 (2004) 2187–2195
2189
due to higher steric influence of bulky 6-O-trityl group
as well as higher polarity of hydroxymethyl group in
comparison with methyl or isobutyl. Although selective
acid hydrolysis of 6-O-trityl protective group to afford
relatively low yields of 6 and 9 is possible, for prepara-
tive purposes, the one-step acid hydrolysis (to increase
the solubility of the products in water for the next reac-
tion step) of both 6-O-trityl and 2,3-O-isopropylidene
protective group in 4 and 5 is more convenient because
of higher overall yields of 7 and 10. Subsequent basic
hydrolysis of the hydantoin ring in 7 and 10 afforded
the desired a-amino acids 8 and 11, respectively. Be-
cause, in this case, terminal CH2OH group of parent
saccharide molecule became a part of serine moiety
and the quaternary C-5 atom of a saccharide moiety
coincides with the a-carbon atom of serine, in addition
to methyl (5S)-5-amino-5-C-carboxy-5-deoxy-a-D-lyxo-
hexofuranoside (according to carbohydrate nomen-
clature), compound 11 can be alternatively named as
2-[methyl (4R)-b-L-erythrofuranosid-4-C-yl]-L-serine. In
conclusion, compound 8 (after deprotection) structur-
ally represents the 5-C-carboxymannojirimycin (see
Scheme 1).
The S configuration at C-40 in oxazolidin-20-one 2 was
confirmed by X-ray crystallography. Analogously, the
configuration at C-5 of compounds 3–11 was confirmed
by unambiguously establishing the 5-S configuration
(relatively to known configuration at C-2, C-3 and C-
4) of compound 9 using X-ray analysis. Figures 1 and
2 show molecule and the numbering scheme of com-
pounds 2 and 9, respectively. The H-positions have been
put at calculated positions and were during refinement
riding on their respective pivot atoms. The relevant crys-
tallographic data for 2 and 9 are given in Table 1. A list
of selected torsion angles is given in Table 2.
Figure 2. Numbering scheme and thermal ellipsoids at 50% probability
level of compound 9.
group can impose some conformational rigidity on com-
pounds 2, 4–6 and 9. For compound 2, the values of
relevant torsion angles O4–C1–C2–C3=22.90(7)°, C1–
C2–C3–C4=0.03(9)°, C2–C3–C4–O4=À22.67(7)°, C3–
C4–O4–C1=38.73(7)°, C4–O4–C1–C2=À38.69(7)° and
puckering parameters40 Q=0.361(1)A, U=359.74(12)°
˚
indicate that O4–C1–C2–C3–C4 furanose ring adopts
almost ideal OE conformation. Analogously, the pucker-
˚
ing parameters Q=0.321(1)A, U=148.55(13)° and the
relevant dihedral angles O2–C2–C3–O3=À2.73(7)°,
C2–C3–O3–C10=À18.57(7)°,
C3–O3–C10–O2=
33.36(7)°, O3–C10–O2–C2=À35.43(7)°, C10–O2–C2–
C-10
C3=23.48(7)° are indicative of C-10E conformation
slightly distorted to the
T
O-2
direction for five-mem-
bered 1,3-dioxolane ring (O2–C2–C3–O3–C10) with
C-10 atom lying in the endo and O-2 exo direction with
respect to the C3–O3 reference bond. The five-mem-
bered oxazolidine ring (O6–C6–C5–N2–C8) adopts
almost ideal C-5E conformation, considering the pucker-
The presence of a 1,3-dioxolane ring fused to a fura-
nose ring at the 2,3-position and the a-glycosidic methyl
˚
ing parameters Q=0.211(1)A, U=72.6(2)° and the
relevant torsion angles O6–C6–C5–N2=19.84(7)°,
C6–C5–N2–C8=À21.36(8)°, C5–N2–C8–O6=15.19(9)°,
N2–C8–O6–C6=À0.67(9)°
À12.72(8)°.
and
C8–O6–C6–C5=
Similarly for compound 9, based on the values of rel-
evant torsion angles and puckering parameters
˚
˚
[Q=0.340(3)A, U=0.7(5)° and Q=0.311(3)A, U=
149.7(5)°, respectively], the ideal OE conformation for
O4–C1–C2–C3–C4 furanose ring and C-10E conforma-
C-10
tion slightly distorted to the
T
direction for O2–
O-2
C2–C3–O3–C10 five-membered 1,3-dioxolane ring, was
observed. In contrast with our previously published32–34
planar conformation for five-membered hydantoin
rings, in this case, the puckering parameters
˚
Q=0.082(2)A, U=31.1(17)° as well as relevant dihedral
angles
N1–C5–C7–N2=7.8(2)°,
C5–C7–N2–C8=
À4.6(3)°, C7–N2–C8–N1=À0.9(3)°, N2–C8–N1–C5=
Figure 1. Numbering scheme and atomic displacement ellipsoids at
50% probability level of compound 2.
6.5(3)°, C8–N1–C5–C7=À8.8(3)° are indicative of

ˇ ´
J. Micova et al. / Carbohydrate Research 339 (2004) 2187–2195
2190
Table 1. Crystallographic and experimental data for compounds 2 and 9a
Compound 2
Compound 9
Empirical formula
Formula weight
Temperature, T (K)
C
12H18N2O7
C12H18N2O7
302.28
183(2)
302.28
183(2)
˚
Wavelength, k (A)
0.71073
Tetragonal
P43
0.71073
Orthorhombic
P212121
Crystal system
Space group
Unit cell dimensions
˚
a (A)
9.050
9.050
17.3645(2)
6.19520(10)
15.3460(2)
˚
b (A)
˚
c (A)
15.43380(10)
1467.32(3)
3
˚
Unit-cell volume V (A )
Formula per unit cell, Z
Dcalcd (g/cm3)
1422.321(16)
4
1.412
4
1.368
Radiation
MoKa
0.117
MoKa
0.113
Absorption coefficient, l (mmÀ1
F(000)
Crystal size (mm)
)
640
0.60 (max)
640
0.95 (max)
0.35 (min)
Siemens SMART CCD
2.25–32.81
0.04 (min)
Siemens SMART CCD
2.64–26.43
Diffractometer
h Range (°)
Range of h
À13!13
À7!7
Range of k
Range of l
Reflections
À13!13
À19!19
À26!26
À19!19
25114
17408
Independent reflections
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2r(I)]
R indices (all data)
5053 (Rint =0.0225)
Full-matrix least-squares on F2
5053/1/214
1761 (Rint =0.0621)
Full-matrix least-squares on F2
1761/0/212
1.053
1.091
R1 =0.0263, wR2 =0.0714
R1 =0.0276, wR2 =0.0728
0.240 and À0.196
R1 =0.0367, wR2 =0.0777
R1 =0.0484, wR2 =0.0828
0.194 and À0.173
3
˚
Largest difference peak and hole (e/A )
a Standard deviations in parentheses.
Table 2. Selected torsion angles (°) for compounds 2 and 9a
EC-5 conformation for N1–C5–C7–N2–C8 hydantoin
ring.
Compound 2
Compound 9
C1–C2–C3–C4
O4–C1–C2–C3
C2–C3–C4–O4
C1–O4–C4–C3
C4–O4–C1–C2
O2–C2–C3–O3
C10–O3–C3–C2
C3–O3–C10–O2
C2–O2–C10–O3
C10–O2–C2–C3
O1–C1–C2–O2
O1–C1–O4–C4
C1–C2–C3–O3
O2–C2–C3–C4
O4–C4–C5–C6
C7–C5–C6–O6
N2–C5–C6–O6
C8–O6–C6–C5
C6–O6–C8–N2
C5–N2–C8–O6
C8–N2–C5–C6
C8–N1–C5–C7
C8–N2–C7–C5
N1–C5–C7–N2
C5–N1–C8–N2
C7–N2–C8–N1
0.03(7)
22.90(7)
À0.7(3)
22.3(3)
Analysis of the molecular packing in the unit cell of
compound 2 revealed four principal hydrogen bonds
and three weak hydrogen bonds of C–HÁ Á ÁO type (Table
3), which give rise to a number of interactions in many
directions. Two of them, [c] and [d], are intramolecular,
while the other are intermolecular (Fig. 3). The first level
descriptors based on the graph-set theory41 include
intramolecular strings S1,1(6) formed by bond [c] and
S1,1(5) formed by bond [d], chains C1,1(7), formed by
bond [a], C1,1(8) (bonds [b] and [e]), C1,1(5) (bond [f])
and C1,1(9) (bond [g]). The second level comprises:
chains C2,2(6) (bonds [b] and [c], [b] and [e]), C2,2(15)
(bonds [a] and [b], [a] and [e]), C2,2(11) (bonds [a], [b];
[b], [e]; [b], [f] and [b], [g]), C1,2(9) (bonds [a], [e]),
C2,2(9) (bonds [a] and [f]), C2,2(12) (bonds [a], [f]; [e],
[f] and [e], [g]), C2,2(14) (bonds [a], [g] and [f], [g]),
C2,2(16) (bonds [a], [g] and [b], [e]), C2,2(17) (bonds
[b], [g] and [e], [g]), C2,2(13) (bonds [e], [f]) and
C1,2(10) (bonds [f], [g]; also R2,2(13) ring defined by
the hydrogen bonds [b] and [f] was found. Assignment
of the H-bond descriptors, based on the graph-set the-
ory41 was obtained using the program PLUTO.42 For con-
venience, the notation Xa,d(n) has also been adopted in
À22.67(7)
38.73(7)
À21.1(2)
36.5(2)
À38.69(7)
À2.73(7)
À18.57(7)
33.36(7)
À36.8(3)
À3.2(3)
À17.8(3)
32.4(3)
À35.43(7)
23.48(7)
À34.8(3)
23.2(3)
152.46(6)
78.26(7)
150.9(2)
80.5(3)
À116.78(6)
114.09(6)
61.93(7)
À118.3(2)
114.5(2)
82.9(2)
140.80(6)
19.84(7)
58.6(3)
À12.72(8)
À0.67(9)
15.19(9)
À21.36(8)
À8.8(3)
À4.6(3)
7.8(2)
6.5(3)
À0.9(3)
a Standard deviations in parentheses.

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J. Micova et al. / Carbohydrate Research 339 (2004) 2187–2195
2191
Table 3. Hydrogen bond geometry in compound 2a
˚
X–H (A)
˚
˚
Notation
X–HÁ Á ÁY
Symmetry code
HÁ Á ÁY (A)
2.06
2.23
XÁ Á ÁY (A)
X–HÁ Á ÁY (°)
172.1
151.7
a
b
c
d
e
f
N1–H1AÁ Á ÁO5ii
N1–H1BÁ Á ÁO1i
N2–H2Á Á ÁO3
y, Àx, z+1/4
0.88
0.88
2.9345(10)
3.0365(10)
2.7958(9)
Ày+1, x, zÀ1/4
0.875(14)
0.88
1.00
2.199(14)
2.39
2.56
125.2(12)
107.6
145.0
N1–H1BÁ Á ÁN2
C2–H2AÁ Á ÁO5iii
C6–H6BÁ Á ÁO7i
C12–H12AÁ Á ÁO7iv
2.7815(10)
3.4298(11)
3.3913(10)
3.5076(12)
Àx, Ày+1, z+1/2
Ày+1, x, zÀ1/4
xÀ1, y, z
0.99
0.98
2.48
2.60
153.0
154.5
g
a Standard deviations in parentheses.
Figure 3. Hydrogen bonding in compound 2. Methyl hydrogen atoms are omitted for clarity. For symmetry codes and notation, see Table 3.
this paper, in which (X) is the pattern descriptor, (a) is
number of acceptors, (d) is number of donors and (n)
is the number of atoms comprising the pattern. For
compound 9 (see Table 4) three strong hydrogen bonds
of types O–HÁ Á ÁO and N–HÁ Á ÁO are present together
with one weak hydrogen bond of C–HÁ Á ÁO. The first-
level descriptors based on the graph-set theory41 include
chains C1,1(7), formed by hydrogen bonds [a], C1,1(5)
([b]) (Fig. 4), C1,1(6) ([c]) and C1,1(8) ([d]). The sec-
ond-level comprises: chains C2,2(10) (bonds [a], [b]
and [b], [c]), C2,2(11) (bonds [a], [b]; [b], [d] and [c],
[d]), C2,2(6) (bonds [a] and [c] (Fig. 5), C2,2(15) (bonds
[a] and [d]), C1,2(9) (bonds [a] and [d]), C2,2(12) (bonds
[b] and [d]) and C2,2(14) (bonds [e] and [d]). Also a ring
R2,2(13), formed by bonds [a] and [c], has been identi-
fied.
3. Experimental
3.1. General methods
The 1H and 13C NMR spectra (in CDCl3 unless specified
other, internal standard Me4Si) were recorded on a Bru-
ker Avance DPX 300 instrument (equipped with gradi-
ent-enhanced spectroscopy kit GRASP for generation
of Z gradient up to 50G/cm) operating at 300.13 and
75.46MHz working frequencies, respectively. For the
assignments of signals, 1D NOESY and C–H heterocor-
related experiments were used. The quaternary carbon
atoms were identified on the basis of a semiselective IN-
EPT experiment and a 1D INADEQUATE pulse
sequence technique. When reporting assignments of
NMR signals, data for the oxazolidine and hydantoin

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J. Micova et al. / Carbohydrate Research 339 (2004) 2187–2195
2192
Table 4. Hydrogen bond geometry in compound 9a
˚
X–H (A)
˚
˚
Notation
X–HÁ Á ÁY
Symmetry code
HÁ Á ÁY (A)
XÁ Á ÁY (A)
X–HÁ Á ÁY (°)
a
b
c
O6–H6Á Á ÁO5ii
N1–H1Á Á ÁO7i
N2–H2Á Á ÁO6ii
C2–H2AÁ Á ÁO5iii
x+1/2, Ày+3/2, Àz
xÀ1, y, z
0.84
0.88
0.88
1.00
1.83
2.10
1.94
2.50
2.667(3)
2.905(3)
2.801(3)
3.454(3)
174.2
151.5
164.2
158.7
x+1/2, Ày+3/2, Àz
Àx+1/2, Ày+1, z+1/2
d
a Standard deviations in parentheses.
Figure 4. A chain parallel with b-axis of hydrogen bonds of N1Á Á ÁO7 type in compound 9. For symmetry code and notation, see Table 4.
a reactive agent) mass spectra (70eV) were obtained on
a Finnigan MAT SSQ 710 instrument. Specific rotations
were determined on a Perkin–Elmer 241 polarimeter
(10cm cell). Microanalyses were performed on a Fisons
EA 1108 analyser. Melting points were determined with
a Boetius PHMK 05 microscope. All reactions were
monitored by TLC on Silica Gel 60 plates (E. Merck)
using the following solvents: 2:3 EtOAc–hexane (eluent
A), 10:1 CHCl3–MeOH (eluent B), 4:1 CHCl3–MeOH
(eluent C), 8:1 CHCl3–MeOH (eluent D), 7:3 MeOH–
water (eluent E). Visualisation was affected with iodine
vapour or H2SO4. Column chromatography was per-
formed as flash chromatography on Silica Gel 60 (E.
Merck, 0.063–0.200mm).
3.2. X-ray techniques
Crystal and experimental data for 2 and 9 are summa-
rised in Table 1. Preliminary orientation matrix was ob-
tained from the first frames using Siemens SMART
software.43 Final cell parameters were obtained by
refinement of 7505 (for 2) and 8087 (for 9) reflections
Figure 5. Chains and rings of hydrogen bonds of type N2Á Á ÁO6
and O6Á Á ÁO5 in compound 9. For symmetry code and notation, see
Table 4.
using Siemens SAINT software.43 The data were empiri-
cally corrected for absorption and other effects using
SADABS program44 based on the method of Blessing.45
The structures were solved by direct methods and
refined by full-matrix least-squares on all F2 data using
Bruker SHELXTL.46 The non-H atoms were refined aniso-
residue are identified by a prime and those for the phen-
yls by a double prime. The EI and CI (using pyridine as

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J. Micova et al. / Carbohydrate Research 339 (2004) 2187–2195
2193
tropically. Hydrogen atoms were constrained to the
ideal geometry using an appropriate riding model.
Molecular graphics were obtained using the program
DIAMOND.47
200 and C-600), 127.2 (C-40), 112.9 (CMe2), 106.2 (C-1),
87.4 (CPh3), 84.8 (C-2), 80.0 (C-3), 77.2 (C-4), 67.6
(C-50), 63.8 (CH2), 54.6 (OCH3), 25.8 and 24.3
[(CH3)2C]; EIMS (70eV): m/z 259, 243 (100%,
[Ph3C]+), 239, 165, 105, 43. Anal. Calcd for
C31H32N2O7: C, 68.40; H, 5.92; N, 5.14. Found: C,
68.43; H, 5.98; N, 5.11.
3.3. (40S)-40-Carbamoyl-40-[methyl (4R)-2,3-O-isopropyl-
idene-b-L-erythrofuranosid-4-C-yl]-oxazolidin-20-one (2)
3.5. (50S)-Triphenylmethoxymethyl-50-[methyl (4R)-2,3-
O-isopropylidene-b-L-erythrofuranosid-4-C-yl]-imidazol-
idin-20,40-dione (5)
To a solution of 5-ulose 1 (6.97g, 30mmol) in 50% aque-
ous EtOH (50mL) was added KCN (3.90g, 60mmol)
and (NH4)2CO3 (13.45g, 140mmol) and the mixture
was stirred at 60°C for 8h. Ethanol was then evaporated
and the product extracted with CHCl3. After complete
solvent removal in vacuo, the residue was chromato-
graphed on a column of silica gel with eluent D. The
fractions having Rf 0.70 were collected and evaporated
to give 2 (3.90g, 43%). Recrystallisation from EtOAc af-
forded white needles with mp 235–237°C; [a]D +126 (c 1,
The fractions having Rf 0.36 (eluent A) from the above
column chromatography were collected and evaporated.
Recrystallisation of the product from toluene gave pure
5 as white needles (6.86g, 42% yield); mp 264–265°C;
1
[a]D +29 (c 1, CHCl3); NMR: H (300MHz, CDCl3): d
7.78 (br s, 1H, NH), 7.42–7.18 (m, 15H, aromatic),
5.31 (br s, 1H, NH), 4.86 (s, 1H, H-1), 4.73 (dd, 1H,
J2,3 5.9Hz, J3,4 3.8Hz, H-3), 4.45 (d, 1H, H-2), 3.96
1
MeOH); NMR: H (300MHz, CDCl3): d 6.80 and 5.67
(2br s, each 1H, NH2), 6.09 (br s, 1H, NH), 4.98 (s, 1H,
H-1), 4.82 (dd, 1H, J2,3 5.9Hz, J3,4 3.4Hz, H-3), 4.57 (d,
(d, 1H, H-4), 3.54 and 3.45 (2d of ABq, each 1H, JHa,Hb
,
9.2Hz, CH2), 3.18 (s, 3H, OCH3), 1.32 and 1.18 (2s,
each 3H, Me2C); 13C (75.5MHz, CDCl3): d 173.5 (CO
at C-40), 156.4 (CO at C-20), 143.3 (C-100), 128.6 (C-300
and C-500), 127.9 (C-200 and C-600), 127.2 (C-40), 113.1
(CMe2), 106.7 (C-1), 87.0 (CPh3), 84.3 (C-2), 79.7 (C-
3), 77.4 (C-4), 66.4 (C-50), 65.8 (CH2), 54.9 (OCH3),
25.4 and 24.0 [(CH3)2C]; EIMS (70eV): m/z 259, 243
(100%, [Ph3C]+), 239, 165, 105, 43. Anal. Calcd for
C31H32N2O7: C, 68.40; H, 5.92; N, 5.14. Found: C,
68.41; H, 5.99; N, 5.09.
1H, H-2), 4.56 and 4.46 (2d of ABq, each 1H, JHa,Hb
,
8.8Hz, CH2), 4.45 (d, 1H, H-4), 3.35 (s, 3H, OCH3),
1.54 and 1.28 (2s, each 3H, Me2C); 13C (75.5MHz,
CDCl3): d 172.9 (CONH2), 159.1 (CO at C-20), 113.2
(CMe2), 106.9 (C-1), 85.1 (C-2), 79.9 (C-3), 78.6 (C-4),
72.6 (CH2), 64.0 (C-4), 55.0 (OCH3), 25.8 and 23.9
[(CH3)2C]; EIMS (70eV): m/z 287 [MÀMe]+, 258
(100%, [MÀCONH2]+), 226, 170, 134, 75, 53, 40. CIMS:
m/z 382 (M+C5H5NH)+. Anal. Calcd for C12H18N2O7:
C, 47.70; H, 6.00; N, 9.27. Found: C, 47.81; H, 6.08,
N, 9.20.
3.6. (50R)-Hydroxymethyl-50-[methyl (4R)-2,3-O-isoprop-
ylidene-b-L-erythrofuranosid-4-C-yl]-imidazolidin-20,40-
dione (6)
3.4. (50R)-Triphenylmethoxymethyl-50-[methyl (4R)-2,3-
O-isopropylidene-b-L-erythrofuranosid-4-C-yl]-imidazol-
idin-20,40-dione (4)
To a magnetically stirred solution of hydantoin 4 (5.45g,
10mmol) in concentrated acetic acid (75mL) heated at
60°C, water (50mL) was slowly added and the solution
was stirred at this temperature for 3h. After cooling to
rt, the separated triphenylmethanol was filtered off and
the solvent was evaporated on vacuum rotatory evapo-
rator. The crude product (Rf 0.55, eluent B) was recrys-
tallised from EtOAc affording 6 as white needles (1.27g,
42% yield); mp 187–188°C; [a]D +103 (c 1, MeOH);
NMR: 1H (300MHz, D2O): d 5.03 (s, 1H, H-1),
4.97 (dd, 1H, J2,3 5.9Hz, J3,4 3.5Hz, H-3), 4.70 (d, 1H,
H-2), 4.23 (d, 1H, H-4), 4.01 and 3.87 (2d of ABq,
each 1H, JHa,Hb, 11.8Hz, CH2), 3.33 (s, 3H, OCH3),
1.48 and 1.33 (2s, each 3H, Me2C); 13C (75.5MHz,
D2O): d 177.7 (CO at C-40), 160.2 (CO at C-20), 114.7
(CMe2), 106.9 (C-1), 84.5 (C-2), 79.8 (C-3), 78.8 (C-4),
69.0 (C-50), 63.1 (CH2), 55.4 (OCH3), 25.0 and 24.2
[(CH3)2C]; EIMS (70eV): m/z 287 [MÀMe]+, 272, 173,
154, 85, 59, 43 (100%). Anal. Calcd for C12H18N2O7:
Starting from 5-ulose 3 (14.23g, 30mmol) and applica-
tion of the same reaction procedure as described for
the preparation of 2 afforded a mixture of hydantoins
4 and 5, which were separated on a column of silica
gel using solvent A as an eluent. The fractions having
Rf 0.59 (eluent A) were collected and evaporated.
Recrystallisation of the product from EtOAc–hexane
gave pure 4 as white needles (1.80g, 11% yield); mp
209–210°C; [a]D +75 (c 1, CHCl3); NMR: 1H
(300MHz, CDCl3): d 8.80 (br s, 1H, NH), 7.45–7.20
(m, 15H, aromatic), 5.89 (br s, 1H, NH), 4.83 (s, 1H,
H-1), 4.61 (dd, 1H, J2,3 5.8Hz, J3,4 3.2Hz, H-3), 4.45
(d, 1H, H-2), 4.07 (d, 1H, H-4), 3.52 and 3.41 (2d of
ABq, each 1H, JHa,Hb, 9.4Hz, CH2), 3.18 (s, 3H,
OCH3), 1.47 and 1.24 (2s, each 3H, Me2C); 13C
(75.5MHz, CDCl3): d 173.6 (CO at C-40), 157.0 (CO
at C-20), 143.1 (C-100), 128.6 (C-300 and C-500), 127.9 (C-

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J. Micova et al. / Carbohydrate Research 339 (2004) 2187–2195
2194
C, 47.70; H, 6.00; N, 9.27. Found: C, 47.78; H, 6.11; N,
9.20.
3.9. (50S)-Hydroxymethyl-50-[methyl (4R)-2,3-O-isoprop-
ylidene-b-L-erythrofuranosid-4-C-yl]-imidazolidin-20,40-
dione (9)
3.7. (50R)-Hydroxymethyl-50-[methyl (4R)-b-L-erythro-
furanosid-4-C-yl]-imidazolidin-20,40-dione (7)
The same reaction procedure as described for the prep-
aration of 6 was applied. The crude product (Rf 0.47,
eluent B) was recrystallised from EtOAc–hexane to give
pure 9 as white needles (1.33g, 44% yield); mp 229–
A magnetically stirred solution of hydantoin 4 (5.45g,
10mmol) in diluted acetic acid (75%, 75mL) was heated
at 60°C for 3h and then at 70°C for 16h. After cooling
to rt, the separated triphenylmethanol was filtered off
and the solvent was evaporated to dryness under dimin-
ished pressure and co-evaporated twice with toluene.
The residue was chromatographed on a column of silica
gel with eluent C. The fractions having Rf 0.42 were col-
lected and evaporated to give pure 7 (1.65g, 63% yield).
Analytical sample (white needles) was obtained by re-
crystallisation from EtOH; mp 203–204°C; [a]D +93 (c
1, H2O); NMR: 1H (300MHz, D2O): d 4.97 (d, 1H,
J1,2 4.4Hz, H-1), 4.39 (d, 1H, J3,4 3.8Hz, H-4), 4.37
(dd, 1H, J2,3 4.4Hz, H-3), 4.09 (t, 1H, H-2), 3.90 (s,
2H, CH2), 3.42 (s, 3H, OCH3); 13C (75.5MHz, D2O):
d 178.2 (CO at C-40), 160.4 (CO at C-20), 108.9 (C-1),
79.1 (C-4), 76.5 (C-2), 71.5 (C-3), 70.9 (C-50), 62.0
(CH2), 57.1 (OCH3). Anal. Calcd for C9H14N2O7: C,
41.20; H, 5.38; N, 10.70. Found: C, 41.09; H, 5.30; N,
10.62.
1
230°C; [a]D +29 (c 1, MeOH); NMR: H (300MHz,
D2O): d 5.09 (s, 1H, H-1), 4.91 (dd, 1H, J2,3 6.0Hz,
J3,4 4.2Hz, H-3), 4.71 (d, 1H, H-2), 4.10 (d, 1H, H-4),
3.95 and 3.89 (2d of ABq, each 1H, JHa,Hb, 11.8Hz,
CH2), 3.34 (s, 3H, OCH3), 1.41 and 1.29 (2s, each 3H,
13
Me2C); C (75.5MHz, D2O): d 177.8 (CO at C-40),
160.4 (CO at C-20), 114.6 (CMe2), 106.6 (C-1), 84.8
(C-2), 80.2 (C-3), 77.8 (C-4), 69.0 (C-50), 65.0 (CH2),
55.4 (OCH3), 25.2 and 24.2 [(CH3)2C]; EIMS (70eV):
m/z 287 [MÀMe]+, 272, 173, 154, 85, 59, 43 (100%).
Anal. Calcd for C12H18N2O7: C, 47.70; H, 6.00; N,
9.27. Found: C, 47.61; H, 6.06; N, 9.19.
3.10. (50S)-Hydroxymethyl-50-[methyl (4R)-b-L-erythro-
furanosid-4-C-yl]-imidazolidin-20,40-dione (10)
The same reaction procedure as described for the prep-
aration of 7 was applied. The fractions having Rf 0.32
(eluent C) from the column chromatography were col-
lected and evaporated. Recrystallisation of the product
from EtOH gave pure 10 as white needles (1.70g, 65%
yield); mp 36–37°C; [a]D +48 (c 1, H2O); NMR: 1H
(300MHz, D2O): d 5.00 (d, 1H, J1,2 3.1Hz, H-1), 4.42
(t, 1H, J2,3 5.1Hz, J3,4 5.1Hz, H-3), 4.32 (d, 1H, H-4),
4.05 (dd, 1H, H-2), 3.91 (s, 2H, CH2), 3.42 (s, 3H,
3.8. Methyl (5R)-5-amino-5-C-carboxy-5-deoxy-a-D-
lyxo-hexofuranoside {2-[methyl (4R)-b-L-erythrofurano-
sid-4-C-yl]-D-serine} (8)
A mixture of hydantoin 7 (1.31g, 5mmol), barium
hydroxide octahydrate (4.73g, 15mmol) and water
(50mL) was heated under reflux for 6h. Carbon dioxide
gas was then passed to the hot reaction mixture. The sep-
arated barium carbonate was removed by filtration and
washed with hot water. Carbon dioxide gas was again
passed to the hot solution and after cooling to room
temperature, another portion of barium carbonate
separated. Filtration and decolourising with charcoal
gave clear solution. Water was evaporated under dimin-
ished pressure and the residual solid was purified on a
short column of silica gel (eluent E). Fractions with Rf
0.68 (eluent E) were collected and evaporated to afford
8 (391mg, 33%). Analytical sample (white solid) was
obtained by recrystallisation from water–methanol;
mp 107°C (dec.); [a]D +124 (c 0.4, H2O); NMR: 1H
(300MHz, D2O): d 5.00 (d, 1H, J1,2 1.4Hz, H-1),
4.50 (dd, 1H, J2,3 4.3Hz, J3,4 6.8Hz, H-3), 4.47 (d,
1H, H-4), 4.06 (dd, 1H, H-2), 3.94 and 3.91 (2d of
ABq, each 1H, JHa,Hb, 11.9Hz, CH2), 3.36 (s, 3H,
OCH3); 13C (75.5MHz, D2O): d 175.9 (CO), 108.7 (C-
1), 79.3 (C-4), 76.4 (C-2), 72.5 (C-3), 67.3 (C-50), 64.6
(CH2), 56.7 (OCH3). Anal. Calcd for C8H15NO7: C,
40.50; H, 6.37; N, 5.90. Found: C, 40.59; H, 6.44; N,
5.82.
13
OCH3); C (75.5MHz, D2O): d 178.1 (CO at C-40),
160.6 (CO at C-20), 108.8 (C-1), 78.7 (C-4), 75.5 (C-2),
72.0 (C-3), 69.7 (C-50), 64.5 (CH2), 56.7 (OCH3). Anal.
Calcd for C9H14N2O7: C, 41.20; H, 5.38; N, 10.70.
Found: C, 41.29; H, 5.40; N, 10.66.
3.11. Methyl (5S)-5-amino-5-C-carboxy-5-deoxy-a-D-
lyxo-hexofuranoside {2-[methyl (4R)-b-L-erythrofurano-
sid-4-C-yl]-L-serine} (11)
Starting from 10 (1.31g, 5mmol) and application of the
same reaction procedure as described for the preparation
of 8 afforded 11 (415mg, 35%). Analytical sample (white
solid) was obtained by recrystallisation from water–
methanol; mp 110°C (dec.); [a]D +65 (c 0.4, H2O);
1
NMR: H (300MHz, D2O): d 5.02 (d, 1H, J1,2 4.0Hz,
H-1), 4.42 (d, 1H, J3,4 3.0Hz, H-4), 4.41 (dd, 1H, J2,3
4.0Hz, H-3), 4.09 (t, 1H, H-2), 3.97 and 3.92 (2d of
ABq, each 1H, JHa,Hb, 11.8Hz, CH2), 3.45 (s, 3H,
OCH3); 13C (75.5MHz, D2O): d 175.5 (CO), 109.0 (C-
1), 78.4 (C-4), 76.2 (C-2), 73.1 (C-3), 66.8 (C-50), 64.8
(CH2), 57.0 (OCH3). Anal. Calcd for C8H15NO7: C,
40.50; H, 6.37; N, 5.90. Found: C, 40.56; H, 6.45; N, 5.85.

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J. Micova et al. / Carbohydrate Research 339 (2004) 2187–2195
2195
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pound 2 and 9, respectively. Copies of this information
may be obtained free of charge from the Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
(Fax: +44-1223-336033; e-mail: deposit@ccdc.cam.ac.
uk or www: http://www.ccdc.cam.ac.uk).
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The authors thank K. Paule, J. Tonka, A. Karovic˘ova,
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A. Kanska and Dr. V. Pa¨toprsty (Institute of Chemis-
try) for microanalyses, optical rotation, NMR and mass
spectral measurements. Financial support of this work
by the Scientific Grant Agency (VEGA, Slovak Acad-
emy of Sciences, Grant Nos 2/3077/23 and 2/3104/23)
is gratefully appreciated.
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