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Synlett 2003(9): 1283-1286
DOI: 10.1055/s-2003-40336
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

Dialkyl Imidazolium Benzoates - Room Temperature Ionic Liquids Useful in the Peracetylation and Perbenzoylation of Simple and Sulfated Saccharides

Saravanababu Murugesana, Nathalie Karstb, Tasneem Islamb, John M. Wienceka, Robert J. Linhardt*a-c
a Department of Chemical and Biochemical Engineering, The University of Iowa, Iowa City, IA-52242, USA
b Department of Chemistry, The University of Iowa, Iowa City, IA-52242, USA
c Department of Medicinal and Natural Products Chemistry, The University of Iowa, Iowa City, IA-52242, USA
Fax: +1(319)3356634; e-Mail: robert-linhardt@uiowa.edu;
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Publication History

Received 27 March 2003
Publication Date:
30 June 2003 (online)

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Abstract

Dialkyl imidazolium benzoates, room temperature ionic liquids including 1-ethyl-3-methyl imidazolium benzoate, 1-butyl-3-methyl imidazolium benzoate and 1-hexyl-3-methyl imidazolium benzoate were used in the peracetylation and perbenzoylation of several simple and sulfated carbohydrates. Organic solvents and catalysts were not required in the syntheses and these ionic liquids gave excellent yields in short reaction times.

Key words

carbohydrates - sulfated sugars - acylation - ionic liquids - microwave

    References

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  • 13 NMR data: [emIm][ba]: 1H NMR (DMSO, 400 MHz) δ 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) δ 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) δ 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).
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NMR data: Compound (1): 1H NMR (D2O, 400 MHz) δ 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) δ 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) δ 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) δ 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) δ 4.39-4.69 (5.25 H, m, H-5α,β, H-6aα,β, H-6bα,β), 5.69 (1 H, dd, J = 3.7 Hz, 10.3 Hz, H-2α), 5.80-5.90 (2.5 H, m, H-4α, H-2β, H-4β), 6.05 (0.75 H, t, J = 9.4 Hz, H-3β), 6.30 (0.75 H, d, J = 7.9 Hz, H-1β), 6.33 (1 H, t, J = 10.0 Hz, H-3α), 6.85 (1 H, d, J = 3.7 Hz, H-1α), 8.18-7.27 (25 H, m, Ar).

17

MS (ESI): 461 [M + H+].