Synthesis and X-ray structure of a C5-C4-linked glucofuranose-oxazolidin-2-one

Article abstract of DOI:10.1016/j.carres.2009.06.031

The formation of (4R)-4-carbamoyl-4-[(4R)-3-O-benzyl-1,2-O-isopropylidene-β-l-threofuranos-4-C-yl]-oxazolidin-2-one instead of expected imidazolidin-2,4-dione (hydantoin) derivative from 5-amino-5-cyano-5-deoxy-3-O-benzyl-1,2-O-isopropylidene-α-d-glucofur

Full text of DOI:10.1016/j.carres.2009.06.031

Carbohydrate Research 344 (2009) 2079–2082
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Note
Synthesis and X-ray structure of a C5–C4-linked
glucofuranose–oxazolidin-2-one
Bohumil Steiner a, Vratislav Langer b, Miroslav Koóš a,
*
a Institute of Chemistry, Centre of Excelence GLYCOMED, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 38 Bratislava, Slovakia
b Environmental Inorganic Chemistry, Department of Chemical and Biological Engineering, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 29 April 2009
Received in revised form 3 June 2009
Accepted 17 June 2009
Available online 26 June 2009
The formation of (4R)-4-carbamoyl-4-[(4R)-3-O-benzyl-1,2-O-isopropylidene-b-L-threofuranos-4-C-yl]-
oxazolidin-2-one instead of expected imidazolidin-2,4-dione (hydantoin) derivative from 5-amino-
5-cyano-5-deoxy-3-O-benzyl-1,2-O-isopropylidene- -glucofuranose or 3-O-benzyl-1,2-O-isopropyli-
dene-
a
-D
a-D-xylo-hexofuranos-5-ulose under Bucherer–Bergs reaction conditions is reported. Single crystal
X-ray diffraction data revealed that 3T4 is the prefered conformation for the furanose ring, while E2 and
2T1 conformations are adopted by the 1,3-dioxolane and 2-oxazolidinone five-membered rings,
respectively.
Keywords:
Oxazolidin-2-one
Bucherer–Bergs reaction
Glucofuranose
Ó 2009 Elsevier Ltd. All rights reserved.
X-ray diffraction
Conformation
Glycoconjugate
Derivatives of oxazolidin-2-one represent an important class of
synthetic biologically active agents.1–4 Some of them have also
been therapeutically applied (e.g., Zolmitriptan, used as a drug
for acute treatment of migraine).5 In addition, functionalized chiral
oxazolidin-2-ones, known as Evans’ chiral auxiliaries,6,7 have
widely been applied as versatile chiral building blocks in asymmet-
ric syntheses of biologically active compounds or their intermedi-
problematic. Due to very similar Rf values of several co-products,
supposing a possibility of both R and S diastereomers of corre-
sponding hydantoin and amino nitrile, chromatographic separa-
tion of oxazolidin-2-one derivative of adequate purity, was
unsuccessful. Therefore, we have decided on a two-step approach.
Thus, starting from 5-ulose 1,21,22 the corresponding amino nitrile
was prepared in the first step as a mixture of 5R and 5S isomers (in
the ratio of 60:40 as determined by 1H NMR spectroscopy). The
pure 5R isomer – 5-amino-5-cyano-5-deoxy-3-O-benzyl-1,2-O-iso-
ates.8–12 Among them, a glycoconjugate derived from
D-mannitol
has also been introduced.13 Owing to the above mentioned utilities
and emerging new applications of oxazolidin-2-ones, considerable
attention has been focused on their synthesis. Generally, they are
prepared from 1,2-amino alcohols with phosgene (or diphosgene)
and dialkyl carbonates (or alkyl chloroformates).14–16 The con-
struction of the oxazolidin-2-one ring, its application and modifi-
cation have been surveyed in two recent reviews.17,18
Recently, we have described the Bucherer–Bergs reaction of
some hexofuranos-5-uloses having unprotected 6-OH group,
affording C5–C4-linked glucofuranose–oxazolidin-2-one instead
of expected corresponding imidazolidin-2,4-dione (hydantoin)
derivative.19,20 As a continuation of this work, we have used 3-O-
propylidene-
a-
D-glucofuranose [alternative name: (5R)-5-amino-
5-cyano-5-deoxy-3-O-benzyl-1,2-O-isopropylidene-a-D-xylo-hexof-
uranose] (2) was obtained using column chromatography and sub-
sequent several recrystallizations of the component that eluted
first (Rf 0.72). Our efforts to obtain also the pure 5S isomer were
unsuccessful. Even repeated column chromatography of the slower
moving oily component (Rf 0.65) always afforded product contam-
inated with ca. 15% (as indicated by 1H NMR spectroscopy) of the
5R isomer. In the second step, reaction of amino nitrile 2 with
ammonium carbonate gave desired (4R)-4-carbamoyl-4-[(4R)-3-
O-benzyl-1,2-O-isopropylidene-b-
L-threofuranos-4-C-yl]-oxazoli-
benzyl-1,2-O-isopropylidene-a-D-xylo-hexofuranos-5-ulose (1) as
din-2-one [alternative name: (4R,4R)-4-C-(4-carbamoyl-2-oxoox-
a starting 5-ulose (Scheme 1). In this case, a mixture of products
resulted and, although the oxazolidin-2-one (as seen from the
comparison of TLC and NMR data of the crude reaction mixture)
represented the main product, its isolation and purification were
azolidin-4-yl)-3-O-benzyl-1,2-O-isopropylidene-b-
nose] (3) (Scheme 1).
L-threofura-
The structure of 3 was established on the basis of NMR and
mass spectral data. The R configuration at C4 position of oxazolid-
inone ring (this position coincides with the C5 position of the
hexofuranose moiety) was confirmed by X-ray crystallography
(Fig. 1, Table 1). The absolute configuration at stereocentres C1,
* Corresponding author. Tel.: +421 2 59410254; fax: +421 2 59410222.
E-mail address: chemmiro@savba.sk (M. Koóš).
0008-6215/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2009.06.031

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B. Steiner et al. / Carbohydrate Research 344 (2009) 2079–2082
NH2
C
H
CH2OH
C
O
H2N
N
CN
O
O
O
O
O
HO
O
a
b
H
O
H
H
O
O
O
O
O
O
O
O
2
1
3
Scheme 1. Reagent and conditions: (a) NH3 in MeOH, NaCN, NH4Cl, 20 °C, 48 h; (b) (NH4)2CO3, aq EtOH, 60 °C, 8 h.
Table 1
C2, C3 and C4 of the furanose moiety in 3 was assigned on the basis
of the known arrangement in analogous -glucofuranose deriva-
Crystallographic and experimental data for compound 3a
D
tives. Analogously, the R configuration at C5 position in amino ni-
trile 2 was then deduced from the known arrangement of atoms in
3 and considering the usual mechanism of the Bucherer–Bergs
reaction23,24 that reaction with ammonium carbonate should pro-
ceed via an attack of carbon dioxide at amino group of 3, leaving
the C5 position of hexofuranose unaffected.
The presence of a 1,3-dioxolane ring bonded to a furanose ring at
the 1,2-position imposes some conformational rigidity on com-
pound 3. An inspection of the relevant torsion angle values (Table
2) and the calculated values of ring puckering parameters25
Empirical formula
Formula weight
Temperature, T (K)
Wavelength, k (Å)
Crystal system
Space group
C18H22N2O7
378.38
183(2)
0.71073
Orthorhombic
P212121
6.8333(1)
a (Å)
b (Å)
c (Å)
8.7368(1)
30.6410(2)
1829.30(4)
4
1.374
0.107
Unit-cell volume V (Å3)
Formula per unit cell, Z
Dcalcd (g/cm3)
Absorption coefficient,
F(0 0 0)
Crystal size (mm)
h Range for data collection (°)
Index ranges
l
(mmꢀ1
)
Q = 0.373(3) Å and
U = 304.1(4)° revealed that O4–C1–C2–C3–C4
furanose ring adopts the 3T4 (C3TC4) conformation with C3 atom lying
in the endo and C4 exo direction with respect to the O4–C1–C2 refer-
ence plane. Analogously, the puckering parameters Q = 0.174(3) Å,
800
0.52 ꢁ 0.10 ꢁ 0.02
2.42–27.49
ꢀ8 ꢂ h ꢃ 8
ꢀ11 ꢂ k ꢃ 11
ꢀ39 ꢂ l ꢃ 39
23905
U
= 256.9(9)° and the values of relevant dihedral angles (Table 2)
are indicative of a conformation very close to E2 (envelope on C2)
for five-membered 1,3-dioxolane ring (O1–C1–C2–O2–C10). Con-
Reflections collected
Independent reflections (Rint
Completeness to h (%)
Refinement method
)
2434 (0.0609)
99.9
sidering the puckering parameters Q = 0.271(3) Å,
U = 56.4(6)° and
Full-matrix least-squares on F2
2434/42/310
1.014
the relevant torsion angle values (Table 2), the conformation of the
five-membered oxazolidine ring (O6–C6–C5–N2–C8) can be de-
scribed mainly as a 2T1 (C5TC6, twisted on C6–C5).
Inspection of the molecular packing in the unit cell revealed 3
principal hydrogen bonds (see Fig. 2, Table 3) and 4 weak contacts,
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2
r
(I)]
R1 = 0.0446, wR2 = 0.1047
R1 = 0.0576, wR2 = 0.1123
0.398 and ꢀ0.295
R indices (all data)
Largest difference peak and hole (e/Åꢀ3
)
a
Standard deviations in parentheses.
among them 3 were intramolecular ([d], [f], [g]) and 4 were inter-
molecular ([a], [b], [c], [e]). The first level hydrogen bond descrip-
tors based on the graph-set theory26 comprise: chains C(8) for [a],
C(7) for [b], C(4) for [c] and C(6) for [e], strings (intramolecular
contacts) S(5) for [d], [f] and [g]. The second level includes: ring
R1,2(7) for [b,c] and chains C2,2(15) for [a,b], C2,2,(11) for [a,b],
[a,e], [b,c] and [c,e], C2,2(14) for [a,c] and [a,e], C2,2(13) for [b,e],
C2,2(10) also for [b,e] and C2,2(9) for [c,e]. Assignment of the
hydrogen bond descriptors, based on the graph-set theory26 was
27
performed using the program PLUTO
.
1. Experimental
1.1. General methods
The 1H and 13C NMR spectra (in CDCl3, internal standard Me4Si)
were recorded on a Bruker Avance DPX 300 instrument (equipped
with gradient-enhanced spectroscopy kit GRASP for generation of Z
gradient up to 50 Gauss/cm) operating at 300.13 and 75.46 MHz,
respectively. The quaternary carbon atoms were identified on the
basis of a semiselective INEPT experiment and a 1D INADEQUATE
pulse sequence technique. When reporting assignments of 13C
NMR signals, data for the phenyls are identified by a prime. The
EI and CI (using pyridine as a reactive agent) mass spectra
Figure 1. A perspective drawing of 3 showing the atom-numbering. Hydrogen
atoms are masked by short bonds for clarity. Displacement ellipsoids are shown at
30% probability level. The structure is disordered in the orientation of the phenyl
ring. The occupancy was refined to 0.53(2) and 0.47(2), respectively; the part with
lower occupancy is shown in broken lines. The dihedral angle between the two
disordered phenyl rings is 18.6(9)°.

B. Steiner et al. / Carbohydrate Research 344 (2009) 2079–2082
2081
Table 2
Relevant torsion angles (°) for five-membered rings in compound 3a
Furanose
1,3-Dioxolane
Oxazolidin-2-one
O4–C1–C2–C3
C1–C2–C3–C4
C2–C3–C4–O4
C3–C4–O4–C1
C4–O4–C1–C2
ꢀ12.4(3)
30.4(3)
O1–C1–C2–O2
C1–C2–O2–C10
C2–O2–C10–O1
O2–C10–O1–C1
C10–O1–C1–C2
ꢀ16.9(3)
18.8(3)
ꢀ13.2(3)
1.5(3)
O6–C6–C5–N2
C6–C5–N2–C8
C5–N2–C8–O6
N2–C8–O6–C6
C8–O6–C6–C5
ꢀ26.7(2)
ꢀ23.9(3)
11.3(3)
8.1(3)
ꢀ22.8(3)
ꢀ38.7(3)
32.7(3)
ꢀ12.4(3)
9.6(3)
a
Standard deviations in parentheses.
1.2. 5-Amino-5-cyano-5-deoxy-3-O-benzyl-1,2-O-
isopropylidene- -glucofuranose [alternative name: (5R)-5-
a
-D
amino-5-cyano-5-deoxy-3-O-benzyl-1,2-O-isopropylidene-
a-D-
xylo-hexofuranose] (2)
To a soln of 5-ulose 1 (3.08 g, 10 mmol) in MeOH (150 mL) were
added NaCN (0.98 g, 20 mmol) and NH4Cl (1.07 g, 20 mmol). The
mixture was saturated with ammonia and stirred for 48 h at room
temperature. Methanol was then evaporated under reduced pres-
sure, the residue was dissolved in water (60 mL) and the product
extracted with diethyl ether (3 ꢁ 30 mL). The combined extracts
were washed with satd aq soln of NH4HCO3 (20 mL) and water
(20 mL), successively, dried over MgSO4, filtered and concentrated
under diminished pressure. The crude product (1.74 g, 52%) was
chromatographed on a column of silica gel using 2:1 EtOAc–hex-
ane as an eluent. The fractions having Rf 0.72 were collected and
evaporated to give almost pure product. Three recrystallizations
from MeOH afforded white crystals of 2 (1.04 g, 31%) with mp
131–132 °C; [
a]
ꢀ44 (c 1, MeOH); 1H NMR (CDCl3): d 7.45–7.31
D
(m, 5H, aromatic), 6.05 (d, 1H, J1,2 = 3.7 Hz, H-1), 4.86 and 4.50
(2d of ABq, each 1H, JHa,Hb = 12.1 Hz, CH2Ph), 4.68 (d, 1H, H-2),
4.14 (d, 1H, J3,4 = 3.8 Hz, H-4), 4.01 (d, 1H, H-3), 4.01 and 3.59
(2d of ABq, each 1H, JHa,Hb = 11.1 Hz, H-6), 2.19 (br s, 2H, NH2),
1.47 and 1.33 (2s, each 3H, Me2C); 13C NMR (CDCl3): d 136.3 (C-
10), 128.8 (C-20 and C-60), 128.4 (C-40), 128.0 (C-30 and C-50),
121.3 (CN), 112.2 (CMe2), 105.5 (C-1), 81.3 (C-2), 81.2 (C-4), 80.8
(C-3), 71.7 (CH2Ph), 67.2 (C-6), 56.0 (C-5), 26.8 and 26.2
[(CH3)2C]. Anal. Calcd for C17H22N2O5: C, 61.10; H, 6.63; N, 8.38.
Found: C, 61.27; H, 6.72, N, 8.30.
Evaporation of the fractions with Rf 0.65 (following the elution of
2) gave, even after three repeated separations, corresponding 5S iso-
Figure 2. Unit cell contents of 3 in projection along the b-axis. Hydrogen bonds [a],
[b] and [c] (see Table 3 for details) are shown as broken lines.
mer of 2 (0.7 g, 21%) in only ca. 85% purity as an oil with [
a
]D ꢀ32 (c 1,
MeOH); 1H NMR (CDCl3): d 7.43–7.28 (m, 5H, aromatic), 6.02 (d, 1H,
J1,2 = 3.7 Hz, H-1), 4.71 and 4.62 (2d of ABq, each 1H, JHa,Hb = 11.0 Hz,
CH2Ph), 4.64 (d, 1H, H-2), 4.29 (d, 1H, J3,4 = 3.7 Hz, H-4), 4.25 (d, 1H,
H-3), 3.69 (s, 2H, H-6), 1.49 and 1.33 (2s, each 3H, Me2C); 13C NMR
(CDCl3): d 136.3 (C-10), 128.5 (C-20 and C-60), 128.2 (C-40), 128.0 (C-
30 and C-50), 120.8 (CN), 112.2 (CMe2), 105.2 (C-1), 83.3 (C-2), 81.7
(C-4), 79.4 (C-3), 72.7 (CH2Ph), 65.3 (C-6), 55.9 (C-5), 26.7 and 26.1
[(CH3)2C]. Anal. Calcd for C17H22N2O5: C, 61.10; H, 6.63; N, 8.38.
Found: C, 61.27; H, 6.71, N, 8.46.
Table 3
Hydrogen bonds (Å) and angles (°) for 3a
Notation
D–Hꢄ ꢄ ꢄA
D–H
Hꢄ ꢄ ꢄA
Dꢄ ꢄ ꢄA
D–Hꢄ ꢄ ꢄA
a
b
c
d
e
f
N1–H1Aꢄ ꢄ ꢄO1i
N1–H1Bꢄ ꢄ ꢄO5ii
N2–H2ꢄ ꢄ ꢄO5ii
N1–H1Bꢄ ꢄ ꢄN2
C3–H3ꢄ ꢄ ꢄO6iii
C6–H6Aꢄ ꢄ ꢄO7
C6–H6Bꢄ ꢄ ꢄO4
0.88
0.88
0.88
0.88
1.00
0.99
0.99
2.04
2.25
2.13
2.42
2.40
2.43
2.55
2.910(3)
3.128(3)
2.840(3)
2.763(4)
3.260(3)
2.852(4)
2.966(3)
172
174
138
103
143
105
105
g
1.3. (4R)-4-Carbamoyl-4-[(4R)-3-O-benzyl-1,2-O-
a
isopropylidene-b-
[alternative name: (4R,4R)-4-C-(4-carbamoyl-2-oxooxazolidin-
4-yl)-3-O-benzyl-1,2-O-isopropylidene-b- -threofuranose] (3)
L-threofuranos-4-C-yl]-oxazolidin-2-one
Standard deviations in parentheses. Symmetry codes: (i) x, y ꢀ 1, z; (ii) x + 1/2,
ꢀy + 1/2, ꢀz; (iii) x + 1, y, z.
L
A mixture of amino nitrile 2 (668 mg, 2 mmol) and (NH4)2CO3
(864 mg, 9 mmol) in 50% aq EtOH (10 mL) was stirred for 8 h at
60 °C. Ethanol was then evaporated and the product extracted with
CHCl3. After complete solvent removal under diminished pressure,
the residue was chromatographed on a column of silica gel using
10:1 CHCl3–MeOH as an eluent. The fractions having Rf 0.45 were
collected and evaporated to give 3 (582 mg, 77%). Recrystallization
(70 eV) were obtained on a Finnigan MAT SSQ 710 instrument.
Specific rotations were determined on a Perkin–Elmer 241 polar-
imeter (10 cm cell). Microanalyses were performed on a Fisons
EA 1108 analyzer. Melting points were determined with a Boetius
PHMK 05 microscope. Column chromatography was performed as
flash chromatography on Silica Gel 60 (E. Merck, 0.063–0.200 mm).

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B. Steiner et al. / Carbohydrate Research 344 (2009) 2079–2082
from MeOH afforded white needles with mp 198–199 °C; [
a
]
D +48
search and Development Agency (Grant No. APVV-0366-07) is
gratefully appreciated.
(c 1, MeOH); 1H NMR (CDCl3): d 7.42–7.31 (m, 5H, aromatic), 6.63
and 5.55 (2br s, each 1H, NH2), 5.69 (br s, 1H, NH), 5.97 (d, 1H,
J1,2 = 3.4 Hz, H-1), 4.69 (d, 1H, J3,4 = 3.2 Hz, H-4), 4.58 (d, 1H, H-2),
4.62 and 4.49 (2d of ABq, each 1H, JHa,Hb = 11.6 Hz, H-5), 4.38 and
4.32 (2d of ABq, each 1H, JHa,Hb = 12.1 Hz, CH2Ph), 4.14 (d, 1H, H-
3), 1.53 and 1.32 (2s, each 3H, Me2C); 13C NMR (CDCl3): d 172.8
(CONH2), 159.1 (OCONH), 135.9 (C-10), 128.9 (C-20 and C-60),
128.7 (C-30 and C-50), 128.6 (C-40), 112.6 (CMe2), 105.1 (C-1), 81.6
(C-3), 80.9 (C-4), 80.8 (C-2), 72.1 (C-5), 70.8 (CH2Ph), 63.1 (C-4 of
oxazolidinone), 26.9 and 26.3 [(CH3)2C]; EIMS (70 eV): m/z 334
(44%, [MꢀCONH2]+), 249, 129, 92, 91 (100%), 65, 43. CIMS: m/z
458 (M+C5H5NH)+. Anal. Calcd for C18H22N2O7: C, 57.10; H, 5.86;
N, 7.40. Found: C, 57.33; H, 5.94, N, 7.31.
References
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were obtained by slow crystallization of 3 from MeOH under cool-
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32
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ˇ
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Financial support of this work by the Scientific Grant Agency
(VEGA, Grant Nos. 2/0128/08 and 2/0199/09) and by the Slovak Re-