Some non-anomerically C-C-linked carbohydrate amino acids related to leucine - Synthesis and structure determination

Article abstract of DOI:10.1016/S0008-6215(03)00176-9

(5′R)-5′-Isobutyl-5′-[methyl (4R)-2,3-O-isopropylidene-β-L-erythrofuranosid-4-C-yl]-imidazolidin- 2′,4′-dione was synthesised starting from methyl 2,3-O-isopropylidene-α-D-lyxo-pentodialdo-1,4-furanoside via methyl 6-deoxy-6-isopropyl-2,3-O-isopropylidene-α-D-lyxo-hexofuranosid-5-ulose applying the Bucherer-Bergs reaction. Its 5′-R configuration was confirmed by X-ray crystallography. Corresponding α-amino acid-methyl (5R)-5-amino-5-C-carboxy-5,6-dideoxy-6-isopropyl-α-D-lyxo- hexofuranoside (alternative name: 2-[methyl (4R)-β-L-erythrofuranosid-4-C-yl]-D-leucine) was obtained from the above hydantoin by acid hydrolysis of the isopropylidene group followed by basic hydrolysis of the hydantoin ring. Analogous derivatives with 5S configuration, formed in a minority, were also isolated and characterised.

Full text of DOI:10.1016/S0008-6215(03)00176-9

Carbohydrate Research 338 (2003) 1349ꢀ1357
/
www.elsevier.com/locate/carres
Some non-anomerically Cꢀ
/
C-linked carbohydrate amino acids
related to leucine*synthesis and structure determination
/
Bohumil Steiner,a Ju´lia Micˇova´,a Miroslav Koo´sˇ,a,* Vratislav Langer,b
Dalma Gyepesova´c
a Institute of Chemistry, Slovak Academy of Sciences, Du´bravska´ cesta 9, SK-84538 Bratislava, Slovakia
b Department of Inorganic Environmental Chemistry, Chalmers University of Technology, SE-41296 Gothenburg, Sweden
c Institute of Inorganic Chemistry, Slovak Academy of Sciences, Du´bravska´ cesta 9, SK-84536 Bratislava, Slovakia
Received 31 January 2003; accepted 11 April 2003
Abstract
(5?R)-5?-Isobutyl-5?-[methyl (4R)-2,3-O-isopropylidene-b-
starting from methyl 2,3-O-isopropylidene-a- -lyxo-pentodialdo-1,4-furanoside via methyl 6-deoxy-6-isopropyl-2,3-O-isopropyli-
dene-a- -lyxo-hexofuranosid-5-ulose applying the BuchererꢀBergs reaction. Its 5?-R configuration was confirmed by X-ray
crystallography. Corresponding a-amino acidꢀmethyl (5R)-5-amino-5-C-carboxy-5,6-dideoxy-6-isopropyl-a- -lyxo-hexofurano-
side (alternative name: 2-[methyl (4R)-b- -erythrofuranosid-4-C-yl]- -leucine) was obtained from the above hydantoin by acid
L
-erythrofuranosid-4-C-yl]-imidazolidin-2?,4?-dione was synthesised
D
D
/
/
D
L
D
hydrolysis of the isopropylidene group followed by basic hydrolysis of the hydantoin ring. Analogous derivatives with 5S
configuration, formed in a minority, were also isolated and characterised.
# 2003 Elsevier Science Ltd. All rights reserved.
Keywords: Sugar amino acids; Hydantoins, Leucine; Buchererꢀ
hexofuranosid-5-ulose; X-ray crystallography
/
Bergs reaction; Methyl 6-deoxy-6-isopropyl-2,3-O-isopropylidene-a-D-lyxo-
1. Introduction
during the past decade. To improve the metabolic
stability of these potential drugs, a lot of more stable
Carbohydrate moieties of glycoproteins and glycolipids
play an important role in a variety of biological events,
especially in recognition phenomena and immune re-
sponse.1 Their decisive influence on conformation,
solubility and stabilization 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 aim to
develop new powerful glycosidase inhibitors and effec-
tive compounds for drug design. In this respect, many
O- and N-linked (mainly anomerically) glycoproteins
have been synthesised and studied intensively especially
glycosyl analogs with a Cꢀ
the carbohydrate moiety and the peptide have been
synthesised.3ꢀ18 On the other hand, not too much
glycoconjugate analogs with a Cꢀ
glucidic position (excluding
/
C anomeric bond between
/C bond in another
anomeric) are
described19ꢀ27 until now. Recently, three useful reviews
on sugar amino acids have been published by Dondoni
and co-workers,28 Schweizer,29 and Kessler and co-
workers.30
In this paper, we present the synthesis and structure
determination of some glycoconjugate model com-
pounds having C-2-linked a-amino acid attached to a
carbohydrate backbone in the C-5 position. Thus,
leucine derivatives branched at C-2 atom are obtained
from suitably O-protected 6-deoxy-6-isopropyl-hexofur-
anos-5-ulose. Further studies on the preparation of
analogous glycoconjugates of serine and phenylalanine,
respectively, are in progress.
* Corresponding author. Tel.: ꢁ
2-59410222.
E-mail address: chemmiro@savba.sk (M. Koo´sˇ).
/
421-2-5910254; fax: ꢁ421-
/
0008-6215/03/$ - see front matter # 2003 Elsevier Science Ltd. All rights reserved.
doi:10.1016/S0008-6215(03)00176-9

1350
B. Steiner et al. / Carbohydrate Research 338 (2003) 1349ꢀ1357
/
2. Results and discussion
chromatography for both 4 and 5, rather difficult.
Therefore, only approx 6% of pure 5 was isolated.
Acid hydrolysis of 2,3-O-isopropylidene group in 4 and
5 (to increase the solubility of the products 6 and 8 in
water) and subsequent basic hydrolysis of the hydantoin
afforded the desired amino acids 7 and 9, respectively.
The quaternary C-5 atom of a saccharide moiety
coincides in this case with the a-carbon atom of leucine
and therefore, in addition to (5R)-5-amino-5-C-car-
Hydrolysis of hydantoins (imidazolidin-2,4-diones),
which can be prepared conveniently by the Buchererꢀ
Bergs reaction, provides a useful route to many a-amino
acids. Up to now, many sugar hydantoins have been
described.7,8,19ꢀ21,25,26,31ꢀ39 However, for their prepara-
/
tion, the BuchererꢀBergs reaction has been applied only
/
several times.19,20,25,26,32 Recently, we have pub-
lished25,26 the synthesis of some sugar a-amino acids
via corresponding hydantoin derivatives starting from
boxy-5,6-dideoxy-6-isopropyl-a-
(according to carbohydrate nomenclature), compound 7
can be alternatively named as 2-[methyl (4R)-b-
erythrofuranosid-4-C-yl]- -leucine.
D-lyxo-hexofuranoside
methyl
pyranosid-4-ulose, methyl 6-deoxy-2,3-O-isopropyli-
-lyxo-hexofuranosid-5-ulose and methyl 6-
6-deoxy-2,3-O-isopropylidene-a-
L-lyxo-hexo-
L-
D
dene-a-
D
Because of the obvious difficulties in unambiguous
establishing the configuration at quaternary C-5 atom
(R versus S) by NMR methods, suitable crystals of
compound 4 were subjected to X-ray analysis which
confirmed 5-R configuration relatively to known con-
figuration at C-2, C-3 and C-4. Fig. 1 shows molecule
and the numbering scheme of compound 4. The H-
positions have been put at calculated positions and were
during refinement riding on their respective pivot atoms.
The relevant crystallographic data for 4 are given in
Table 1. The bond lengths and bond angles are listed in
Table 2. A list of selected torsion angles is given in Table
3. The final positional parameters for compound 4 are
summarised in Table 4.
deoxy-2,3-O-isopropylidene-a-
ulose.
L-lyxo-hexofuranosid-5-
To prepare the corresponding 5-ulose, we have started
-lyxo-
from the known methyl 2,3-O-isopropylidene-a-
D
pentodialdo-1,4-furanoside (1).40,41 The Grignard reac-
tion of 1 with isobutylmagnesium bromide afforded a
mixture of methyl 6-deoxy-6-isopropyl-2,3-O-isopropy-
lidene-a-
propyl-2,3-O-isopropylidene-b-
small amount of methyl 2,3-O-isopropylidene-a-
D
-mannofuranoside and methyl 6-deoxy-6-iso-
-gulofuranoside (2) and
-lyx-
L
D
ofuranoside (product of side-reduction of starting alde-
hyde 1). A mixture of alcohols 2 was, without
separation, subsequently oxidised with pyridinium di-
chromate to give methyl 6-deoxy-6-isopropyl-2,3-O-
The presence of a 1,3-dioxolane ring fused to a
furanose ring at the C-2,3 and the a-glycosidic methyl
group imposes some conformational rigidity on 4. The
isopropylidene-a-
D
-lyxo-hexofuranosid-5-ulose (3) in
Bergs reaction
high yield. Application of the Buchererꢀ
/
to this 5-ulose led to the formation of the corresponding
hydantoin derivatives 4 and 5 (Scheme 1). The stereo-
selectivity of this reaction was higher than 80% (based
on the analysis of NMR spectra) in favour of the
hydantoin 4 having R configuration at C-5 and the
isolation and purification of isomer with S configura-
tion at C-5 (5) was, due to very similar behaviour on
values of relevant torsion angles O-4ꢀ
17.57(13)8, C-1ꢀC-2ꢀC-3ꢀC-4ꢂ7.88(13)8, C-2ꢀ
C-4ꢀO-4ꢂ 30.45(12)8, C-3ꢀC-4ꢀO-4ꢀC-1ꢂ
43.33(12)8, C-4ꢀO-4ꢀ C-2ꢂ 38.09(13)8 and
puckering parameters42 Qꢂ
0.389(1) A, 8ꢂ348.1(2)8
indicate that O-4ꢀC-1ꢀC-2ꢀC-3ꢀC-4 furanoside ring
adopts the OE conformation which is significantly
/
C-1ꢀ
/
C-2ꢀ
/
C-3ꢂ
/
/
/
/
/
/
C-3ꢀ
/
/
/
ꢃ
/
/
/
/
/
/
/
C-1ꢀ
/
/
ꢃ
/
˚
/
/
/
/
/
/
Scheme 1.

B. Steiner et al. / Carbohydrate Research 338 (2003) 1349ꢀ
/1357
1351
Table 1
Crystallographic and experimental data for compound 4 a
4
Empirical formula
Formula weight
Temperature, T (K)
C15H24N2O6
328.36
183(2)
˚
Wavelength, l (A)
0.71073
orthorhombic
P212121
Crystal system
Space group
Unit cell dimensions
˚
a (A)
6.9749(1)
11.1165(1)
21.1876(3)
1642.81(4)
4
˚
b (A)
˚
c (A)
3
˚
Unit-cell volume V (A )
Formula per unit cell, Z
Dcalcd (g/cm3)
1.328
Mo Ka
Radiation
Absorption coefficient, m (mmꢃ1) 0.103
Fig. 1. Numbering scheme and atomic displacement ellipsoids
at 50% probability level of compound 4.
F(000)
Crystal size (mm)
704
1.00 (max)
O-4
deformed to the
oriented endo and C-4 exo to the reference plane defined
T
direction with O-4 atom
0.10 (min)
Siemens SMART CCD
C-4
Diffractometer
u Range (8)
Range of h
2.66ꢀ
100
160
310
29019
5966 (Rint
/
33.00
by the atoms C-1, C-2, and C-3. Analogously, the
˚
ꢃ
/
/
10
16
32
puckering parameters Qꢂ
/
0.196(1) A, 8ꢂ348.9(4)8
/
Range of k
Range of l
ꢃ
/
/
and the relevant dihedral angles O-2ꢀ
8.76(14)8, C-2ꢀC-3ꢀO-3ꢀC-13ꢂ4.79(14)8, C-3ꢀ
C-13ꢀO-2ꢂ 16.31(15)8, O-3ꢀC-13ꢀO-2ꢀC-2ꢂ
C-3ꢂꢃ19.29(15)8 are indi-
/
C-2ꢀ
/
C-3ꢀ
/
O-3ꢂ
O-3ꢀ
/
/
ꢃ
/
/
/
/
/
/
/
/
Reflections
Independent reflections
Refinement method
/
/
ꢃ
/
/
/
/
ꢂ0.0487)
/
22.27(15)8, C-13ꢀ
/
O-2ꢀ
/
C-2ꢀ
/
/
/
full-matrix least-squares
on F2
5966/0/235
cative of O-2E conformation significantly distorted to
O-2
the
T
direction for 5-membered 1,3-dioxolane
C-13
Data/restraints/parameters
ring (O-2ꢀ
/
C-2ꢀ
/
C-3ꢀ
/
O-3ꢀ
/
C-13) with O-2 atom lying
Final R indices [I ꢀ
/
2s(I)]
R1ꢂ
R1ꢂ
1.014
0.3 (7)
/
0.0452, wR2ꢂ
/
0.1293
R indices (all data)
Goodness-of-fit on F2
Absolute structure parameter
/
0.0594, wR2ꢂ
/
0.1416
in the endo and C-13 exo direction with respect to the
plane defined by the atoms C-2, C-3, and O-3. The 5-
ꢃ
/
membered N-1ꢀ
almost planar as all relevant torsion angles are close to
zero.
/
C-5ꢀ
/
C-11ꢀ
/
N-2ꢀ/C-12 hydantoin ring is
Largest difference peak and hole 0.515 and ꢃ0.417
/
3
(e/A )
˚
a
Analysis of the molecular packing in the unit cell of
the compound 4 (Fig. 2) revealed seven hydrogen
mediated interactions (Table 5). First three of them
are classical hydrogen bonds, while rest of them are
week CÁ Á ÁN and CÁ Á ÁO interactions. Two of hydrogen
bonds, notated as [a] and [d] are intramolecular inter-
actions. Assignment of the H-bond descriptors was
based on the graph-set theory.43 Full set of the first-
Standard deviations in parentheses.
symmetry related molecules are shown. The other weak
CÁ Á ÁN and CÁ Á ÁO interactions further stabilise the
structure.
3. Experimental
and second-level descriptors has been obtained using the
44
program PLUTO
.
For convenience, the notation
3.1. General methods
Xa,d(n) has also been adopted in 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. The first-level descriptors based
on the graph-set theory43 include just two C1,1(4)
chains, formed by hydrogen bonds [b] and [c], respec-
tively, while the second-level comprises a chain C1,2(6)
and a R2,2(8) ring defined by the hydrogen bonds [b]
and [c]. The above mentioned chains and rings are
visualised in Fig. 3, where just 5-membered rings of the
1H and 13C NMR spectra (in CDCl3 unless specified
other, internal standard Me4Si) were recorded on a
Bruker Avance DPX 300 instrument operating at 300.13
and 75.46 MHz working frequencies, respectively. For
the assignments of signals, 1D NOESY and Cꢀ
/
H
heterocorrelated experiments were used. The quaternary
carbon atoms were identified on the basis of a semi-
selective INEPT experiment and a 1D INADEQUATE
pulse sequence technique. The EI and CI (using Py as a

1352
B. Steiner et al. / Carbohydrate Research 338 (2003) 1349ꢀ
/1357
Table 2 (Continued)
Table 2
a
˚
Bond lengths (A) and bond angles (8) for compound 4
4
4
C11ꢀ
C7ꢀC6ꢀ
C9ꢀC7ꢀ
C9ꢀC7ꢀ
C8ꢀC7ꢀ
O5ꢀ
O5ꢀ
N2ꢀ
O6ꢀ
O6ꢀ
N1ꢀ
O3ꢀ
O3ꢀ
O2ꢀ
O3ꢀ
O2ꢀ
C15ꢀ
/
C5ꢀ
/
C6
113.00(11)
118.28(12)
110.19(17)
115.62(16)
109.53(13)
127.09(13)
126.52(12)
106.39(11)
127.24(13)
124.62(13)
108.13(11)
105.09(11)
108.37(12)
108.52(12)
111.49(12)
110.57(12)
112.48(13)
˚
Bond lengths (A)
/
/
C5
C8
C6
C6
/
/
O1ꢀ
O1ꢀ
O2ꢀ
O2ꢀ
O3ꢀ
O3ꢀ
O4ꢀ
O4ꢀ
O5ꢀ
O6ꢀ
N1ꢀ
N1ꢀ
N1ꢀ
N2ꢀ
N2ꢀ
N2ꢀ
C1ꢀ
C2ꢀ
C3ꢀ
C4ꢀ
C5ꢀ
C5ꢀ
C6ꢀ
C7ꢀ
C7ꢀ
/
C1
1.4060(17)
1.426(2)
/
/
/C10
/
/
/C2
1.4144(18)
1.4393(17)
1.4246(16)
1.4393(16)
1.4223(16)
1.4416(16)
1.2104(17)
1.2363(15)
1.3314(17)
1.4603(16)
0.8800
/
C11ꢀ
C11ꢀ
C11ꢀ
C12ꢀ
C12ꢀ
C12ꢀ
C13ꢀ
C13ꢀ
C13ꢀ
C13ꢀ
C13ꢀ
C13ꢀ
/
N2
/C13
/
/
C5
/C3
/
/
C5
N1
N2
/C13
/
/
/C1
/
/
/C4
/
/
N2
/C11
/
/
O2
/C12
/
/
C15
C15
C14
C14
/
C12
C5
/
/
/
/
/
/
H1
C11
C12
H2
C2
/
/
/
1.3765(17)
1.3982(17)
0.8800
/
/
C14
/
/
a
Standard deviations in parentheses.
/
1.536(2)
/C3
1.5471(19)
1.5312(19)
1.5379(18)
1.548(2)
/C4
Table 3
Selected torsion angles (8) for compound 4 a
/C5
/C11
/C6
1.5380(18)
1.532(2)
4
/C7
/C9
1.481(3)
1.519(2)
C1ꢀ
O4ꢀ
C2ꢀ
C1ꢀ
C4ꢀ
O2ꢀ
C13ꢀ
C3ꢀO3ꢀ
C2ꢀO2ꢀ
C13ꢀO2ꢀ
C11ꢀN2ꢀ
C5ꢀN1ꢀC12ꢀ
N1ꢀC5ꢀC11ꢀ
C12ꢀN2ꢀ
C12ꢀN1ꢀ
N1ꢀC5ꢀC11ꢀ
C5ꢀN1ꢀC12ꢀ
C3ꢀC4ꢀC5ꢀ
C4ꢀO4ꢀC1ꢀ
C10ꢀO1ꢀC1ꢀ
C2ꢀO2ꢀC13ꢀ
C3ꢀO3ꢀC13ꢀ
/
C2ꢀ
C1ꢀ
C3ꢀ
O4ꢀ
O4ꢀ
C2ꢀ
O3ꢀ
C13ꢀ
C13ꢀ
C2ꢀ
/
C3ꢀ
C2ꢀ
C4ꢀ
C4ꢀ
C1ꢀ
C3ꢀ
/
C4
7.88(13)
17.57(13)
30.45(12)
43.33(12)
38.09(13)
8.76(14)
/C8
/
/
/
C3
C13ꢀ
/C15
1.504(2)
1.520(2)
/
/
/O4
ꢃ
/
C13ꢀ
/C14
/
/
/
C3
C2
O3
/
/
/
ꢃ
/
Bond angles (8)
/
/
/
C1ꢀ
C2ꢀ
C3ꢀ
C1ꢀ
C12ꢀ
C12ꢀ
C5ꢀN1ꢀ
C11ꢀN2ꢀ
C11ꢀN2ꢀ
C12ꢀN2ꢀ
O1ꢀC1ꢀ
O1ꢀC1ꢀ
O4ꢀC1ꢀ
O2ꢀC2ꢀ
O2ꢀC2ꢀ
C1ꢀC2ꢀ
O3ꢀC3ꢀ
O3ꢀC3ꢀ
C4ꢀC3ꢀ
O4ꢀC4ꢀ
O4ꢀC4ꢀ
C5ꢀC4ꢀ
N1ꢀC5ꢀ
N1ꢀC5ꢀ
C4ꢀC5ꢀ
N1ꢀC5ꢀ
C4ꢀC5ꢀC6
/
O1ꢀ
O2ꢀ
O3ꢀ
O4ꢀ
/
C10
C13
C13
C4
112.51(13)
109.66(10)
110.92(10)
105.30(10)
113.29(11)
123.4
/
/
C3ꢀ
/
C2
4.79(14)
/
/
/
/
/
O2
O3
C3
ꢃ
/
16.31(15)
22.27(15)
19.29(15)
0.16(16)
/
/
/
/
/
/
/
/
/
/
ꢃ
/
/
N1ꢀ
/
C5
H1
/
/
C12ꢀ
/N1
/
N1ꢀ
/
/
/
/N2
ꢃ
/
0.85(15)
0.93(13)
0.53(15)
1.10(14)
/
/
H1
123.4
/
/
/N2
ꢃ
/
/
/
C12
H2
H2
111.49(11)
124.3
124.3
/
/
C11ꢀ
/C5
/
/
/
/
C5ꢀ
/
C11
O5
O6
/
/
/
/
/
179.45(14)
178.25(14)
/
/
O4
C2
C2
C1
C3
111.46(12)
106.47(11)
105.71(11)
114.02(12)
105.28(11)
104.15(11)
114.01(10)
104.46(10)
103.01(11)
109.43(10)
104.06(10)
117.88(11)
113.13(10)
100.69(10)
107.76(11)
114.04(11)
108.02(10)
/
/
/
/
/
/
/
/
C6
O1
O4
ꢃ
/
67.16(14)
77.19(14)
60.90(17)
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
C15
C14
138.03(13)
103.51(13)
/
/C3
/
/
/
/
/C4
a
/
/C2
Standard deviations in parentheses.
/
/C2
/
/C5
reactive agent) mass spectra (70 eV) were obtained on a
Finnigan MAT SSQ 710 instrument. Specific rotations
/
/C3
/
/C3
were determined on a PerkinꢀElmer 241 polarimeter (10
/
/
/
C4
cm 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 thin-layer chromatography (TLC) on
/
/
C11
/
/C11
/
/
C6
/
/

B. Steiner et al. / Carbohydrate Research 338 (2003) 1349ꢀ
/1357
1353
Table 4
CHCl3ꢀMeOH (eluent D). Visualisation was affected
with iodine vapour or H2SO4. Column chromatography
was performed as flash chromatography on Silica Gel 60
/
Atomic coordinates (ꢄ
ment parameters (A ꢄ
/
104) and equivalent isotropic displace-
103) for compound 4 a
2
˚
/
(E. Merck, 0.063ꢀ0.200 mm).
/
Atom
x
y
z
Ueq
O-1
O-2
O-3
O-4
O-5
O-6
N-1
N-2
C-1
C-2
C-3
C-4
C-5
C-6
C-7
C-8
C-9
C-10
C-11
C-12
C-13
C-14
C-15
8194(2)
8101(1)
6542(1)
7837(1)
7854(1)
6913(1)
7633(1)
8467(1)
8009(1)
8598(1)
29(1)
29(1)
22(1)
23(1)
30(1)
28(1)
20(1)
22(1)
24(1)
24(1)
21(1)
20(1)
19(1)
22(1)
32(1)
43(1)
78(1)
40(1)
21(1)
20(1)
24(1)
30(1)
32(1)
3.2. X-ray techniques
4318(2)
4104(2)
8224(2)
10702(2)
8710(2)
7073(2)
10203(2)
7526(2)
5342(2)
5028(2)
7072(2)
7470(2)
6380(2)
6835(3)
5980(3)
6239(6)
10234(3)
9668(2)
8628(2)
3970(2)
5446(2)
1950(2)
Crystal and experimental data for 4 are summarised in
Table 1. Preliminary orientation matrix was obtained
from the first frames using Siemens SMART software.45
Final cell parameters were obtained by refinement of
7690 reflections using Siemens SAINT software.45 The
data were empirically corrected for absorption and other
effects using SADABS program46 based on the method of
Blessing.47 The structures were solved by direct methods
and refined by full-matrix least-squares on all F2 data
10120(1)
7304(1)
8401(1)
8680(1)
7409(1)
7581(1)
8504(1)
8899(1)
9323(1)
10508(1)
11243(2)
12494(2)
10691(2)
8094(2)
9459(1)
8048(1)
6584(1)
5834(1)
6170(2)
10043(1)
9296(1)
9372(1)
7423(1)
7445(1)
7981(1)
8145(1)
8823(1)
8929(1)
9522(1)
9459(1)
10128(1)
6866(1)
8898(1)
9610(1)
8302(1)
8654(1)
8424(1)
using Bruker SHELXTL.
48 The non-H atoms were refined
anisotropically. Hydrogen atoms were constrained to
the ideal geometry using an appropriate riding model.
Molecular graphics were obtained using the program
49
DIAMOND
.
3.3. Methyl 6-deoxy-6-isopropyl-2,3-O-isopropylidene-a-
-lyxo-hexofuranosid-5-ulose (3)
D
Aldehyde 1 (10.11 g, 50 mmol) in dry ether (90 mL) was
added dropwise to the Grignard reagent prepared from
magnesium turnings (3.65 g, 150 mmol) and isobutyl
bromide (20.55 g, 150 mmol) in dry ether (90 mL) and
the reaction mixture was heated under reflux for 1 h.
After cooling to rt, it was poured into cold saturated
aqueous solution of NH4Cl (250 mL) and the product
a
Standard deviations in parentheses.
Silica Gel 60 plates (E. Merck) using the following
solvents: 1:2 EtOAcꢀhexane (eluent A), 3:2 EtOAcꢀ
hexane (eluent B), 10:1 CHCl3ꢀMeOH (eluent C), 1:2
/
/
/
Fig. 2. Molecular packing in the unit cell of compound 4.

1354
B. Steiner et al. / Carbohydrate Research 338 (2003) 1349ꢀ
/1357
Table 5
Hydrogen bond geometry in compound 4 a
˚
H (A)
˚
˚
Notation
Xꢀ
/
HÁ Á ÁY
Symmetry code
Xꢀ
/
HÁ Á ÁY (A)
XÁ Á ÁY (A)
Xꢀ
/
HÁ Á ÁY (8)
a
b
c
d
e
f
N1ꢀ
/
H1Á Á ÁO3
H1Á Á ÁO6
H2Á Á ÁO6
0.88
0.88
0.88
0.98
0.98
0.98
0.98
2.31
2.04
2.13
2.58
2.47
2.52
2.40
2.7869(15)
2.8421(15)
2.9525(16)
3.150(3)
114.1
151.6
156.0
116.9
138.6
171.2
156.5
N1ꢀ
N2ꢀ
C9ꢀ
C14ꢀ
C15ꢀ
C15ꢀ
/
xꢃ
/
1/2, ꢃ
/
yꢁ
/
3/2, ꢃ
/
zꢁ2
/
/
xꢁ1/2, ꢃ
/
/
yꢁ
/
3/2, ꢃ
/
zꢁ2
/
/
H9BÁ Á ÁN1
/
H14AÁ Á ÁO4
H15BÁ Á ÁO1
H15CÁ Á ÁO4
3.266(2)
3.487(2)
3.322(2)
/
ꢃ
/
xꢁ
/
1, yꢃ
/
1/2, ꢃ
/
zꢁ
/3/2
g
/
xꢃ1, y, z
/
a
Standard deviations in parentheses.
filtered off and the solvents were evaporated under
diminished pressure to give the crude product. This was
purified on a column of silica gel using EtOAc as an
eluent. Evaporation of the solvent and recrystallisation
of the product (Rf 0.84, solvent A) from etherꢀ
afforded ketone 3 (8.07 g, 92%) as colourless crystals
with melting point (mp) 34ꢀ35 8C; [a]D 38 (c 1,
CHCl3), ꢁ
218 (c 1, MeOH); NMR: 1H (300 MHz,
/hexane
/
ꢃ
/
/
CDCl3): d 5.03 (s, 1 H, H-1), 5.00 (dd, 1 H, J2,3 5.8, J3,4
4.1 Hz, H-3), 4.56 (d, 1 H, H-2), 4.39 (d, 1 H, H-4), 3.34
(s, 3 H, OCH3), 2.48 (m, 2 H, CH2), 2.23 (m, 1 H, CH of
isopropyl), 1.41 and 1.27 (2 s, each 3 H, Me2C), 0.95 and
0.94 (2 d, each 3 H, JCH,Me 6.7 Hz, Me2C of isopropyl);
13C (75.5 MHz, CDCl3): d 203.1 (C-5), 112.6 (CMe2),
107.2 (C-1), 84.6 (C-4), 83.9 (C-2), 80.7 (C-3), 54.5
(OCH3), 48.7 (CH2), 25.5 and 24.3 [(CH3)2C], 23.1
[CH(CH3)2], 22.4 [(CH3)2CH]; EIMS (70 eV): m/z 259
[Mꢁ
/
1]ꢁ, 243 [MꢃMe]ꢁ, 227, 173, 169, 158, 127, 115,
/
Fig. 3. The most significant hydrogen bonds in compound 4
with codes referring to those in Table 5. Parts of the symmetry
related molecules are omitted for clarity.
113, 99, 87, 85 (100%), 59, 57, 43. Anal. Calcd for
C13H22O5: C, 60.40; H, 8.58. Found: C, 60.68; H, 8.62.
was extracted with ether (3ꢄ100 mL). The combined
/
3.4. (5?R)-5?-Isobutyl-5?-[methyl (4R)-2,3-O-
isopropylidene-b-L-erythrofuranosid-4-C-yl]-
imidazolidin-2?,4?-dione (4)
ethereal extracts were dried (Na2SO4), filtered and the
solvent was evaporated under reduced pressure to afford
the crude product. This was chromatographed on a
column of silica gel using solvent A as an eluent. The
fractions having Rf 0.72 were collected and evaporated
to give a mixture of methyl 6-deoxy-6-isopropyl-2,3-O-
To a solution of 5-ulose 3 (7.75 g, 30 mmol) in 50% aq
EtOH (50 mL) was added NaCN (2.94 g, 60 mmol) and
(NH4)2CO3 (13.45 g, 140 mmol) and the mixture was
stirred at 60 8C for 6 h. Ethanol was then evaporated
and after cooling to room temperature (rt), the first
portion (2.64 g) of 4 crystallised from the aqueous
solution. This was filtered off, the aqueous solution
concentrated under diminished pressure and the residue
chromatographed on a column of silica gel with eluent
B. The fractions having Rf 0.69 were collected and
evaporated to give further portion (1.69 g) of 4. The
combined portions of 4 were recrystallised from
isopropylidene-a-
deoxy-6-isopropyl-2,3-O-isopropylidene-b-
noside (2, 8.84 g, 68%). The fractions with Rf 0.17
afforded methyl 2,3-O-isopropylidene-a- -lyxofurano-
side (1.23 g); EIMS (70 eV): m/z 189 [Mꢃ
Me]ꢁ, 173,
D-mannofuranoside and methyl 6-
L
-gulofura-
D
/
129, 113, 85, 68, 59, 43 (100%). The above mixture of
alcohols 2 (8.84 g, 34 mmol) in CH2Cl2 (120 mL) was
added dropwise to a stirred mixture of pyridinium
dichromate (9.03 g, 24 mmol), CH2Cl2 (120 mL) and
Ac2O (9.5 mL) and the mixture was heated under reflux
for 2.5 h. After cooling and addition of EtOAc (170
mL), the precipitated chromium salts were removed by
filtration and CH2Cl2 was distilled off under reduced
pressure. The separated chromium salts were again
EtOAcꢀ
with mp 268ꢀ
Recrystallisation from water afforded 4 as a hydrate
/hexane affording white needles (4.13 g, 42%)
/
269 8C; [a]D 1408 (c 1, MeOH).
ꢁ
/
1
having mp 130ꢀ
/
131 8C; NMR: H (300 MHz, CDCl3):
d 7.81 (bs, 1 H, NH), 5.83 (bs, 1 H, NH), 4.90 (s, 1 H,

B. Steiner et al. / Carbohydrate Research 338 (2003) 1349ꢀ
/1357
1355
H-1), 4.82 (dd, 1 H, J2,3 5.9, J3,4 3.4 Hz, H-3), 4.55 (d, 1
H, H-2), 4.04 (d, 1 H, H-4), 3.24 (s, 3 H, OCH3), 1.82
(m, 1 H, CH of isobutyl), 1.75 (d, 2 H, CH2), 1.54 and
1.32 (2 s, each 3 H, Me2C), 1.00 and 0.92 (2 d, each 3 H,
JCH,Me 6.1 Hz, Me2C of isobutyl); 13C (75.5 MHz,
CDCl3): d 175.2 (CO at C-4 of hydantoin), 156.4 (CO at
C-2 of hydantoin), 113.1 (CMe2), 106.3 (C-1), 84.6 (C-
2), 79.6 (C-3 and C-4), 67.4 (C-5), 54.6 (OCH3), 40.6
(CH2), 25.8 and 24.1 [(CH3)2C], 24.2 [CH and one of
(CH3)2CH], 23.6 [one of (CH3)2CH]; EIMS (70 eV): m/
H-3), 4.20 (d, 1 H, H-4), 4.03 (dd, 1 H, H-2), 3.43 (s, 3
H, OCH3), 2.02 (dd, 1 H, JCH,H 5.2, JH ,H 14.3 Hz, Ha
of CH2), 1.76 (dd, 1 H, JCH,H 6.8 Hz, Hb of CH2), 1.65
a
a
b
b
(m, 1H, CH of isobutyl), 0.92 and 0.86 (2 d, each 3 H,
JCH,Me 6.5 Hz, Me2C); 13C (75.5 MHz, D2O): d 180.2
(CO at C-4 of hydantoin), 160.0 (CO at C-2 of
hydantoin), 108.7 (C-1), 82.0 (C-4), 76.1 (C-2), 72.0
(C-3), 69.2 (C-5), 56.8 (OCH3), 44.4 (CH2), 24.4 and
23.7 [(CH3)2CH], 24.2 (CHMe2); EIMS (70 eV): m/z
289 [Mꢁ
1]ꢁ, 257, 156, 133, 113, 87, 73, 45 (100%), 43.
Anal. Calcd for C12H20N2O6: C, 50.00; H, 6.99; N, 9.72.
/
z 328 [M]ꢁ, 313 [Mꢃ
/
Me]ꢁ, 297, 210, 173 (100%), 115,
C5H5NH)ꢁ.
113, 87, 85, 59, 43. CIMS: m/z 408 (Mꢁ
/
Found: C, 50.11; H, 7.05; N, 9.69.
Anal. Calcd for C15H24N2O6: C, 54.90; H, 7.37; N, 8.53.
Found: C, 54.79; H, 7.43, N, 8.59.
3.7. Methyl (5R)-5-amino-5-C-carboxy-5,6-dideoxy-6-
isopropyl-a-D-lyxo-hexofuranoside (7)
3.5. (5?S)-5?-Isobutyl-5?-[methyl (4R)-2,3-O-
isopropylidene-b- -erythrofuranosid-4-C-yl]-
imidazolidin-2?,4?-dione (5)
L
A mixture of hydantoin 6 (1.44 g, 5 mmol), barium
hydroxide octahydrate (4.73 g, 15 mmol) and water (50
mL) was heated under reflux for 6 h. Carbon dioxide gas
was then passed to the hot reaction mixture. The
separated 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 rt,
another portion of barium carbonate separated. Filtra-
tion and decolourising with charcoal gave clear solution.
Water was evaporated under diminished pressure and
the residual solid was purified on a short column of
silica gel (eluent D). Fractions with Rf 0.50 (eluent D)
were collected and evaporated to afford 7 (474 mg,
36%). Analytical sample (white solid) was obtained by
The fractions having Rf 0.59 (eluent B) from the above
column chromatography were collected and evaporated.
Recrystallisation of the product from EtOAcꢀ
/
hexane
gave pure 5 as white needles (590 mg, 6% yield); mp
1
197ꢀ
/
198 8C; [a]D
ꢁ78 (c 1, MeOH); NMR: H (300
/
MHz, CDCl3): d 8.58 (bs, 1 H, NH), 5.80 (bs, 1 H, NH),
4.95 (s, 1 H, H-1), 4.73 (dd, 1 H, J2,3 5.9, J3,4 3.5 Hz, H-
3), 4.54 (d, 1 H, H-2), 3.94 (d, 1 H, H-4), 3.34 (s, 3 H,
OCH3), 1.99 (m, 1 H, Ha of CH2), 1.80 (m, 2 H, CH and
Hb of CH2 in isobutyl), 1.42 and 1.22 (2 s, each 3 H,
Me2C), 0.97 and 0.93 (2 d, each 3 H, JCH,Me 6.1 Hz,
Me2C of isobutyl); 13C (75.5 MHz, CDCl3): d 175.5 (CO
at C-4 of hydantoin), 157.2 (CO at C-2 of hydantoin),
113.1 (CMe2), 106.6 (C-1), 84.8 (C-2), 80.2 (C-4), 79.4
(C-3), 65.8 (C-5), 54.9 (OCH3), 45.6 (CH2), 25.4 and
23.4 [(CH3)2C], 24.6 (CH of isobutyl), 24.1 and 23.9
recrystallisation from waterꢀ
/
methanol; mp 195 8C (dec);
1
[a]D 208 (c 0.5, H2O); NMR: H (300 MHz, D2O): d
ꢁ
/
5.01 (d, 1 H, J1,2 4.5 Hz, H-1), 4.53 (d, 1 H, J3,4 2.9 Hz,
H-4), 4.45 (dd, 1 H, J2,3 4.5 Hz, H-3), 4.15 (t, 1 H, H-2),
3.43 (s, 3 H, OCH3), 1.85ꢀ1.70 (m, 3 H, CH and CH2 of
/
[(CH3)2CH]; EIMS (70 eV): m/z 328 [M]ꢁ, 313 [Mꢃ
Me]ꢁ, 297, 210, 173 (100%), 157, 115, 113, 87, 85, 59,
43, CIMS: m/z 408 (Mꢁ
C5H5NH)ꢁ. Anal. Calcd for
/
isobutyl), 0.98 and 0.92 (2 d, each 3 H, JCH,Me 6.3 Hz,
Me2C); 13C (75.5 MHz, D2O): d 174.7 (CO), 108.7 (C-
1), 81.5 (C-4), 77.2 (C-2), 71.9 (C-3), 63.5 (C-5), 56.9
(OCH3), 40.4 (CH2), 24.5 and 23.0 [(CH3)2CH], 24.4
/
C15H24N2O6: C, 54.90; H, 7.37; N, 8.53. Found: 54.81;
H, 7.41; N, 8.49.
(CHMe2); EIMS (70 eV): m/z 218 [Mꢃ
COOH]ꢁ, 144,
/
116, 102, 87, 86 (100%), 74, 73, 57, 44, 43, 42. Anal.
Calcd for C11H21NO6: C, 50.20; H, 8.04; N, 5.32.
Found: C, 50.32; H, 8.13; N, 5.28.
3.6. (5?R)-5?-Isobutyl-5?-[methyl (4R)-b-L-
erythrofuranosid-4-C-yl]-imidazolidin-2?,4?-dione (6)
A suspension of hydantoin 4 (3.28 g, 10 mmol) in diluted
AcOH (70%, 50 mL) was heated at 80 8C for 75 min.
The reaction mixture became clear during the first 15
min. The solvent was evaporated to dryness under
diminished pressure and co-evaporated twice with
toluene. The residual white solid was dissolved in EtOAc
(30 mL), treated with charcoal, filtered and solvent
evaporated. Recrystallisation of the product from
3.8. (5?S)-5?-Isobutyl-5?-[methyl (4R)-b-L-
erythrofuranosid-4-C-yl]-imidazolidin-2?,4?-dione (8)
Starting from 5 (657 mg, 2 mmol) and application of the
same reaction procedure as described for the prepara-
tion of 6 afforded 8 (Rf 0.22, solvent C) as white crystals
(1.93 g, 67%); mp 260ꢀ
/
262 8C; [a]D
ꢁ
/
98 (c 1, H2O), ꢁ
/
188 (c 1, MeOH); NMR: 1H (300 MHz, D2O): d 4.81 (s,
1 H, H-1), 4.29 (dd, 1 H, J2,3 4.6, J3,4 7.6 Hz, H-3), 4.11
(d, 1 H, H-4), 3.99 (d, 1 H, H-2), 3.29 (s, 3 H, OCH3),
EtOAcꢀ
/
hexane afforded pure 6 (Rf 0.37, solvent C) as
188 8C; [a]D ꢁ1488
white needles (1.93 g, 67%); mp 186ꢀ
/
/
1
(c 1, MeOH); NMR: H (300 MHz, D2O): d 4.97 (d, 1
H, J1,2 3.8 Hz, H-1), 4.32 (dd, 1 H, J2,3 4.9, J3,4 4.5 Hz,
1.83ꢀ
/
1.60 (m, 3H, CH and CH2 of isobutyl), 0.94 and
0.87 (2 d, each 3 H, JCH,Me 6.3 Hz, Me2C); 13C (75.5

1356
B. Steiner et al. / Carbohydrate Research 338 (2003) 1349ꢀ1357
/
3. Isono, K.; Asahi, K.; Suzuki, S. J. Am. Chem. Soc. 1969,
91, 7490ꢀ7505.
4. Robins, M. J.; Parker, J. M. R. Can. J. Chem. 1983, 61,
312ꢀ316.
5. Petrusˇ, L.; BeMiller, J. N. Carbohydr. Res. 1992, 230,
197ꢀ200.
6. Gurjar, M. K.; Mainkar, A. S.; Syamala, M. Tetrahedron:
Asymmetry 1993, 4, 2343ꢀ2346.
MHz, D2O): d 180.4 (CO at C-4 of hydantoin), 160.1
(CO at C-2 of hydantoin), 108.4 (C-1), 84.7 (C-4), 75.3
(C-2), 71.8 (C-3), 70.1 (C-5), 56.0 (OCH3), 39.5 (CH2),
24.9 (CHMe2), 24.1 and 23.6 [(CH3)2CH]; EIMS (70
/
/
eV): m/z 289 [Mꢁ
1]ꢁ, 257, 156, 133, 113, 87, 73, 45
(100%), 43. Anal. Calcd for C12H20N2O6: C, 50.00; H,
6.99; N, 9.72. Found: C, 50.11; H, 7.05; N, 9.69.
/
/
/
7. Estevez, J. C.; Estevez, R. J.; Ardron, H.; Wormald, M.
3.9. Methyl (5S)-5-amino-5-C-carboxy-5,6-dideoxy-6-
isopropyl-a-D-lyxo-hexofuranoside (9)
R.; Brown, D.; Fleet, G. W. J. Tetrahedron Lett. 1994, 35,
8885ꢀ
8. Estevez, J. C.; Ardron, H.; Wormald, M. R.; Brown, D.;
Fleet, G. W. J. Tetrahedron Lett. 1994, 35, 8889ꢀ8890.
9. Lay, L.; Meldal, M.; Nicotra, F.; Panza, L.; Russo, G.
Chem. Commun. 1997, 15, 1469ꢀ1470.
/
8888.
/
Starting from 8 (288 mg, 1 mmol) and application of the
same reaction procedure as described for the prepara-
/
tion of 7 afforded 9 (100 mg, 38%); mp 196 8C (dec);
1
10. Estevez, J. C.; Burton, J. W.; Estevez, R. J.; Ardron, H.;
[a]D
4.90 (s, 1 H, H-1), 4.27 (dd, 1 H, J2,3 4.6, J3,4 7.4 Hz, H-
ꢃ
/
578 (c 0.5, H2O); NMR: H (300 MHz, D2O): d
Wormald, M. R.; Dwek, R. A.; Brown, D.; Fleet, G. W. J.
Tetrahedron: Asymmetry 1998, 9, 2137ꢀ
11. Dondoni, A.; Massi, A.; Marra, A. Tetrahedron Lett.
1998, 39, 6601ꢀ6604.
12. Dondoni, A.; Marra, A.; Massi, A. Tetrahedron 1998, 54,
2827ꢀ2832.
13. Westermann, B.; Walter, A.; Diedrichs, N. Angew. Chem.,
Int. Ed. 1999, 38, 3384ꢀ3386.
14. Fuchss, T.; Schmidt, R. R. Synthesis 2000, 259ꢀ
15. Dondoni, A.; Mariotti, G.; Marra, A. Tetrahedron Lett.
2000, 41, 3483ꢀ3486.
16. Dondoni, A.; Giovannini, P. P.; Marra, A. J. Chem. Soc.,
Perkin Trans. 1 2001, 2380ꢀ2388.
17. Nishikawa, T.; Ishikawa, M.; Wada, K.; Isobe, M. Synlett
2001, 945ꢀ947.
18. Westermann, B.; Walter, A.; Florke, U.; Altenbach, H.-J.
/2154.
3), 4.14 (d, 1 H, H-4), 4.00 (t, 1 H, H-2), 3.29 (s, 3 H,
OCH3), 1.82ꢀ
/
1.63 (m, 3 H, CH and CH2 of isobutyl),
0.96 and 0.91 (2 d, each 3 H, JCH,Me 6.3 Hz, Me2C); 13
/
C
(75.5 MHz, D2O): d 175.2 (CO), 108.0 (C-1), 83.5 (C-4),
77.4 (C-2), 70.6 (C-3), 66.2 (C-5), 56.6 (OCH3), 40.6
(CH2), 24.7 and 23.1 [(CH3)2CH], 24.6 (CHMe2); EIMS
/
/
(70 eV): m/z 218 [Mꢃ
COOH]ꢁ, 144, 116, 102, 87, 86
/
/
264.
(100%), 74, 73, 57, 44, 43, 42. Anal. Calcd for
C11H21NO6: C, 50.20; H, 8.04; N, 5.32. Found: C,
50.30; H, 8.10; N, 5.30.
/
/
/
4. Supplementary material
¨
Org. Lett. 2001, 3, 1375ꢀ
19. Yanagisawa, H.; Kinoshita, M.; Nakada, S.; Umezawa, S.
Bull. Chem. Soc. Jpn. 1970, 43, 246ꢀ252.
20. Rosenthal, A.; Dodd, R. R. J. Carbohydr. Nucleos.
Nucleot. 1979, 6, 467ꢀ476.
21. Yoshimura, J.; Kondo, S.; Ihara, M.; Hashimoto, H.
Carbohydr. Res. 1982, 99, 129ꢀ142.
22. Banfi, L.; Beretta, M. G.; Colombo, L.; Gennari, C.;
Scolastico, C. J. Chem. Soc., Perkin Trans. 1 1983, 1613ꢀ
/
1378.
Crystallographic data for the structural analysis has
been deposited with the Cambridge Crystallographic
Data Centre, CCDC No. 195472 for compound 4.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
/
/
/
Cambridge CB2 1EZ, UK (Fax: ꢁ44-1223-336-033;
/
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
/
1619.
23. Czernecki, S.; Horns, S.; Valery, J.-M. J. Org. Chem.
1995, 60, 650ꢀ
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Acknowledgements
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. ˇ
The authors thank K. Paule, J. Tonka, A. Karovicova´,
A. Kanska´, and Dr V. Patoprsty´ (Institute of Chem-
¨
/
. ˇ
istry) for microanalyses, optical rotation, NMR, and
mass spectral measurements. Financial support of this
work by the Scientific Grant Agency (VEGA, Slovak
Academy of Sciences, Grant Nos. 2/3077/23 and 2/3104/
23) is gratefully appreciated.
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