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S. Murugesan et al.
LETTER
Table 3 Preliminary Results of Perbenzoylation of Simple Saccharides
Entry
Compound
(PhCO)2O (equiv) Solvent (equiv)
Time (h)
5.5
Products
10, 11
10, 11
12
Yield (%) Anomeric ratio (a:b)
1
2
3
b-D-glucose
5
5
5
[emIm][ba](4)
[emIm][ba](4)
[emIm][ba](4)
55
54
53
1:1.2
1:0.8
1:0
a-D-glucose
5.0
D-mannose (a:b = 1:0.5)
6.0
(10) Carlin, R. T.; De Long, H. C.; Fuller, J.; Trulove, P. C. J.
Electrochem. Soc. 1994, 141, L73.
(11) Holbrey, J. D.; Seddon, K. R. J. Chem. Soc., Dalton Trans.
1999, 2133.
(12) Namboodiri, V. V.; Varma, R. S. Tetrahedron Lett. 2002,
43, 5381.
uct was precipitated by adding water, recovered by
filtration, and purified by silica gel chromatography
(petroleum ether: ethyl acetate 9:1 → 3:1) to afford an in-
separable mixture of 10 and 11 (213mg, 55%). The iden-
tity and purity were confirmed by 1H NMR.16
(13) NMR data: [emIm][ba]: 1H NMR (DMSO, 400 MHz) d
1.39 (3 H, t, CH3), 3.84 (3 H, s, CH3), 4.16 (2 H, q, CH2),
7.44 (2 H, m, Ph), 7.54 (1 H, m, Ph), 7.70 (1 H, t, J = 1.7 Hz,
Im), 7.79 (1 H, t, J = 1.8 Hz, Im), 7.92 (2 H, m, Ph), 9.25 (1
H, s, Im). [bmIm][ba]: 1H NMR (DMSO, 400 MHz) d 0.91
(3 H, t, CH3), 1.28 (2 H, m, CH2), 1.78 (2 H, m, CH2), 3.88
(3 H, s, CH3), 4.20 (2 H, t, CH2), 7.49 (2 H, m, Ph), 7.60 (1
H, m, Ph), 7.77 (1 H, t, J = 1.7 Hz, Im), 7.84 (1 H, t, J = 1.7
Hz, Im), 7.96 (2 H, m, Ph), 9.36 (1 H, s, Im). [hmIm][ba]:
1H NMR (DMSO, 400MHz) d 0.84 (3 H, t, CH3), 1.24 (6 H,
m, 3 CH2), 1.76 (2 H, m, CH2), 3.84 (3 H, s, CH3), 4.14 (2 H,
t, CH2), 7.16 (1 H, t, J = 1.7 Hz, Im), 7.47 (2 H, m, Ph), 7.59
(1 H, m, Ph), 7.87 (1H, t, J = 1.8 Hz, Im), 7.93 (2 H, m, Ph),
9.24 (1 H, s, Im)..
C6H5COO–
+
N
C2H5
N
OH
OAc
O
CH3
O
NaO3SO
AcO
NaO3SO
HO
OC6H5
OC6H5
Ac2O
OAc
OH
(1)
(8)
Equation 3 Peracetylation of phenyl-4-O-sulfo-b-D-glucopyranose
(1) using 1-ethyl-3-methyl imidazolium benzoate.
In summary, acetylation and benzoylation of unsubstitut-
ed and sulfated monosaccharides have been successfully
accomplished in RTILs. While some a, b selectivity was
observed, at present we are unable to explain this selectiv-
ity.
(14) Foley, K. M.; Griffin, C. C.; Amaya, E. US. Pat. App,
898124, 1990.
(15) Petitou, M.; Coudert, C.; Level, N.; Lormeau, J.-C.; Zuber,
M.; Simenel, C.; Fournier, J.-P.; Choay, J. Carbohydr. Res.
1992, 236, 107.
Future studies will examine these issues as well as extend
the application of these reactions to other sulfated reac-
tants such as GAGs and GAG-derived oligosaccharides.
(16) NMR data: Compound (1): 1H NMR (D2O, 400 MHz) d 3.58
(1 H, dd, J = 7.8 Hz, 9.2 Hz, H-2), 3.62 (1 H, ddd, J = 2.1 Hz,
5.6 Hz, 9.8 Hz, H-5), 3.80 (2 H, m, H-3, H-6b), 3.95 (1 H,
dd, J = 2.1 Hz, 12.5 Hz, H-6a), 4.24 (1 H, dd, J = 9.0 Hz, 9.8
Hz, H-4), 4.97 (1 H, d, J = 7.9 Hz, H-1), 7.01–7.32 (5 H, m,
Ph). Compound (2): 1H NMR (D2O, 400 MHz) d 3.43–3.51
(3 H, m, H-2, H-3, H-4), 3.69 (1 H, ddd, J = 2.0 Hz, 5.8 Hz,
7.6 Hz, H-5), 4.18 (1 H, dd, J = 5.8 Hz, 11.0 Hz, H-6b), 4.39
(1 H, dd, J = 2.0 Hz, 11.0 Hz, H-6a), 4.91 (1 H, d, J = 7.4 Hz,
H-1), 7.00–7.32 (5 H, m, Ph). Compound (8): 1H NMR
(D2O, 400 MHz) d 2.04 (3 H, s, OAc), 2.05 (3 H, s, OAc),
2.06 (3 H, s, OAc), 4.98 (1 H, ddd, J = 2.5 Hz, 6.6 Hz, 9.7
Hz, H-5), 4.37 (1 H, dd, J = 6.6 Hz, 12.2 Hz, H-6b), 4.42–
4.49 (2 H, m, H-4, H-6a), 5.14 (1 H, dd, J = 8.0 Hz, 9.7 Hz,
H-2), 5.27 (1 H, d, J = 8.0 Hz, H-1), 5.38 (1 H, t, J = 9.7 Hz,
H-3), 7.00–7.32 (5 H, m, Ph). Compound (9): 1H NMR
(D2O, 400 MHz) d 2.03 (3 H, s, OAc), 2.08 (3 H, s, OAc),
2.09 (3 H, s, OAc), 4.09–4.21 (3 H, m, H-5, H-6a, H-6b),
5.12 (1 H, t, J = 9.5 Hz, H-4), 5.21 (1 H, dd, J = 8.0 Hz, 9.5
Hz, H-2), 5.33 (1 H, d, J = 8.0 Hz, H-1), 5.42 (1 H, t, J = 9.5
Hz, H-3), 7.05–7.36 (5 H, m, Ph). Compounds (10) and (11):
1H NMR (D2O, 400 MHz) d 4.39–4.69 (5.25 H, m, H-5a,b,
H-6aa,b, H-6ba,b), 5.69 (1 H, dd, J = 3.7 Hz, 10.3 Hz, H-
2a), 5.80–5.90 (2.5 H, m, H-4a, H-2b, H-4b), 6.05 (0.75 H,
t, J = 9.4 Hz, H-3b), 6.30 (0.75 H, d, J = 7.9 Hz, H-1b), 6.33
(1 H, t, J = 10.0 Hz, H-3a), 6.85 (1 H, d, J = 3.7 Hz, H-1a),
8.18–7.27 (25 H, m, Ar).
Acknowledgment
We thank Ms. Erin Steenblock, for her help in preparing ionic li-
quids and conducting some of the reactions. We also acknowledge
the support of the NIH in the form of grant # HL 62244.
References
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(17) MS (ESI): 461 [M + H+].
Synlett 2003, No. 9, 1283–1286 ISSN 1234-567-89 © Thieme Stuttgart · New York