Synthesis of Novel S-Glucosides Containing 5-Methylisoxazole Substituted 1 , 2 , 4-Triazole

Nine new S-ββ-D-glucosides containing 4-aryl-5-(5-methylisoxazol-3-yl)-1,2,4-triazol-3-thiols have been synthesized by the direct glycosylation of 4-aryl-5-(5-methylisoxazol-3-yl)-1,2,4-triazol-3-thiols with 2,3,4,6-tetra-O-acetyl-αα-D-glucopyranosyl bromide in ethanol in the presence of potassium hydroxide followed by deacetylation using dry ammonia in dry methanol. All the compounds synthesized have been characterized by their elemental analyses and spectral data.


Experimental
Melting points were determined on an X-4 microscopic melting point apparatus and were uncorrected. 1H NMR spectra were determined on a Varian Mercury-300 MHz spectrometer at room temperature using TMS as internal standard, coupling constants (J) were measured in Hz.Elemental analysis were performed by Elementar Vario EL apparatus.Commercially available reagents were used throughout without further puri�cation unless otherwise stated.
petroleum ether/ethyl acetate as eluent to afford the pure product.
( the Zemplén deacetylation is not suitable for the deprotection of carbohydrates containing 5-methylisoxazole-substituted 1,2,4-triazole due to the instability of the isoxazole ring under strong basic condition.Finally, the removal of the protecting groups was easily achieved by treatment with dry ammonia gas in dry methanol.e �nal desired S-glucosides containing 5-methylisoxazole-substituted 1,2,4-triazole (3a-3i) were successfully obtained in good yields.e structures of 2a-2i and 3a-3i were con�rmed by elemental analyses and spectral data.e 1 H NMR spectral data of compounds 2a-2i showed the presence of four acetyl groups through the four singlets in the region of 1.94-2.05ppm.In addition, seven hydrogen atoms of the sugar moiety were also observed in these spectra.ey exhibited multiplets at 3.75-5.58ppm.Only -anomer was obtained as judged by a doublet at  5.52-5.58(J 1 = 9.9-10.8Hz) of the anomeric proton (H-1) in the sugar moiety.Compounds 2a-2i showed two singlets at  2.41-2.44 and 6.54-6.64,which were assigned to the protons of methyl and isoxazole ring, respectively.
e 1 H NMR spectra of 3a-3i provided support to successful deacetylation reaction by the disappearance of the four sharp singlets in the region of 1.94-2.05ppm as observed in the spectra of 2a-2i.e aryl groups of compounds 2a-2i and 3a-3i were found in the region of 6.84-7.71ppm.e other 1 H NMR spectral data was found approximately the same as observed in the case of the corresponding acetylated glucosides.e elemental analysis of these compounds was good agreement with calculated values.
Compounds 3a-3i were screened for their antibacterial activity against Escherichia coli and Staphylococcus aureus.e results showed that most of the compounds were inactive against these microorganisms.Further investigation on biological activities is in progress.