The syntheses of 5-pyridyl-3(beta-D-galactopyranosyl)-1,3,4-oxadiazole-2-thiones 3a-3c and 5-pyridyl-2(beta-D-galactopyranosyl)-4-benzyl-1,2, 4-triazole-3-thiones 6a-6c are reported. The existence of N-galactosides--not S-galactosides--was proven by IR and 15N NMR spectroscopy. The structures of the final products and the intermediates were elucidated by IR, 1H, 13C and 15N NMR spectroscopy and mass spectrometry.

Source of materialThe title compound was synthesized by the reaction of ethyl ester of picolinic acid with hydrazine hydrate (80 %) in absolute ethanol. The whole reaction mixture was refluxed for 7 h. The excess of solvent was distilled off, the residue was filtered, washed with water and recrystallized from ethanol (60 %). Colorless thin needle-shaped single crystals suitable for X-ray analysis were obtained by slow evaporation at RT (m.p. 144-145 °C). Experimental detailsWhile the Η atoms bound to Ν atoms were refined freely due to their importance in hydrogen bonding, the Η atoms attached to C atoms were refined using conventional restraints.

Source of materialThe title compound was synthesized by the reaction of ethyl ester of 2-bromobenzoic acid with hydrazine hydrate (80 %) in absolute ethanol. The reaction mixture was refluxed for 7 h. The excess of solvent was distilled off, the residue was filtered and washed with water. Colorless thin needle-shaped single crystals suitable for Xray analysis were obtained by recrystallization from 60 % ethanol. Experimental detailsWhile the H atoms bound to N atoms were refined freely due to their importance in hydrogen bonding, the H atoms attached to C atoms were refined using conventional restraints. DiscussionAromatic hydrazides are a very important intermediate especially in the field of heterocyclic chemistry. Aromatic hydrazide have been used for the synthesis of various biologically active five membered heterocycles such as 2,5-disubstituated-1,3,4-oxadiazoles, 5-substituted-2-mercapto-1,3,4-oxadiazoles etc. Due to its versatilities in the synthesis of various heterocyclic compounds, we have synthesized the title compound and report its structure. The r.m.s. deviation from plane is 0.678 Å in the molecular structure of the title compound. Within phenyl ring, the bond lengths lie between 1.376(4) Å and 1.386(3) Å highlighting the aromatic character. The valence angle C2C1C6 of 121.1(2)°is larger than the standard value (120°). The opening of this angle is due to the presence of the bromo group on C1, which involves a decrease of the ring angles on C1 (118.2 (2)°) and C6 (118.2(2)°). The C7O1 bond distance (1.225(3) Å) is compatible with respective distances in a related structure [2] and smaller than those usually observed in carboxylic acids (1.365 Å). The structure is influenced by quite interesting intra-and intermolecular hydrogen bonding which stabilizes the whole crystal structure.

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Source of materialThe title compound was synthesized by the reaction of ethyl ester of picolinic acid with hydrazine hydrate (80 %) in absolute ethanol. The whole reaction mixture was refluxed for 7 h. The excess of solvent was distilled off, the residue was filtered, washed with water and recrystallized from ethanol (60 %). Colorless thin needle-shaped single crystals suitable for X-ray analysis were obtained by slow evaporation at RT (m.p. 144-145°C). Experimental detailsWhile the H atoms bound to N atoms were refined freely due to their importance in hydrogen bonding, the H atoms attached to C atoms were refined using conventional restraints. DiscussionAromatic hydrazides are a very important intermediate especially in the field of heterocyclic chemistry. Aromatic hydrazide have been used for the synthesis of various biologically active five membered heterocycles such as 2,5-disubstituted 1,3,4-oxadiazoles, 5-substituted 2-mercapto-1,3,4-oxadiazoles etc. Due to its versatilities in the synthesis of various heterocyclic compounds, we have synthesized the title compound and report its structure. The r.m.s. deviation from plane in the molecular structure of the title compound is 0.0171 Å. Within phenyl ring, the bond lengths lie between 1.374(2) Å and 1.388(2) Å which highlight the aromatic character. The valence angles N1C1C2 (123.7(1)°) and N1C5C4 (123.4(1)°) are larger than the standard value (120°). The opening of this angle is due to the presence of the nitrogen atom on 2-position, which involves a decrease of the ring angles of C2 (118.9(1)°), C3 (118.5(1)°) and C4 (118.9(1)°). The C6O1 bond distance (1.235(1) Å) is compatible with respective distances in related structures [2] and smaller than those usually observed in carboxylic acids (1.365 Å). The structure is influenced by quite interesting intra-and intermolecular hydrogen bonding which stabilizes the whole crystal structure.

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Synthesis and Structure Determination of Some Oxadiazole-2-thione and Triazole-3-thione Galactosides. -In order to get novel nucleosides as potential antiviral agents, the new pyridyl-substituted azoles (III) and (X) are synthesized and coupled with galactopyranosyl bromide (IV) to give, after deprotection, the nucleosides (VI) and (XII). The structures of the intermediates and the final products are determined by spectroscopic methods. It is noteworthy that this coupling technique affords the N-galactosides exclusively.