Institute of Chemistry, Slovak Academy of Sciences, Dubravska cesta 9,
SK-84238 Bratislava, Slovak Republic.
Tel. +421-7-378-2540, Fax +421-7-375565 ([email protected])
Received: 23 October 1997 / Published: 31 October 1997
Although the title compound has already been prepared in four steps [1] or three steps [2] from D-galactose, this selective tosylation consists of only a two step synthesis avoiding the preparation of several intermediates and affording much higher overall yields. Moreover, NMR spectral data of the title compound have not yet been published.
To a well stirred solution of methyl alpha-D-galactopyranoside (9.71 g, 50 mmol) [3] in dry pyridine (40 ml) 4-toluenesulfonyl chloride (10.49 g, 55 mmol) was added in small portions at -50 deg.C. The reaction mixture was then kept in a freezer overnight and after reaching laboratory temperature it was poured into ice-water (250 ml). Filtration and recrystallization from ethanol gave the title compound (18.65 g, 90%) as white crystals.
M.p. 170-171 deg.C.
[a]D +105 deg. (c = 10 mg.cm-3, pyridine).
TLC (Chloroform/MeOH 4:1, silica gel): Rf 0.65.
1H-NMR (DMSO-d6): 7.78-7.46 (m, 4H, aromatics); 4.49 (d, J=3.2 Hz, 1H, H-1); 4.12 (dd, J=10.4 and 3.5 Hz, 1H, H-6); 4.03 (dd, J=10.4 and 8.2 Hz, 1H, H-6'); 3.73 (dd, J=8.2 and 3.5 Hz, 1H, H-5); 3.63 (d, J=2.8 Hz, 1H, H-4); 3.51 (dd, J=10.1 and 3.2 Hz, 1H, H-2); 3.45 (dd, J=10.1 and 2.8, 1H, H-3); 3.18 (s, 3H, OCH3), 2.41 (s, 3H, CH3).
13C-NMR (DMSO-d6): 145.2 (C-4'), 132.4 (C-1'), 130.3 (C-3' and C-5'), 127.7 (C-2' and C-6'), 100.0 (C-1), 71.0 (C-6), 68.9 (C-4), 68.8 (C-5), 68.3 (C-3), 67.9 (C-2), 54.6 (OCH3), 21.2 (CH3).
Anal. calc. for C14H20O8S (348.37): C C 48.27, H 5.79, S 9.20; found: C 48.39, H 5.85, S 9.01.
Acknowledgments: The authors would like to thank Scientific Grant Agency (VEGA, project No. 2/4144/97) for financial support.
References and Notes
1. Ohle, H.; Thiel, H. Ber. 1933, 66B, 525-532.
2. Bell, D. J.; Williamson, S. J. Chem. Soc. 1938, 1196-1200.
3. It was dried at 90 deg.C in vacuo for 12 h before using.
Sample availability: Available from the authors and MDPI, MDPI Reg. No.13740.
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