Ribosylation of 2-thioxo-5,6,7,8-tetrahydrobenzo thieno[2,3-d]pyrimidin-4(3H)-one 1a and 2,4-dithioxo-5,6,7,8-tetrahydrobenzo thieno[2,3-d]pyrimidine 1b with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose 7 afforded the benzoylated S-nucleoside derivatives 3 and 4, respectively. Debenzoylation of 3 and 4 by using methanolic sodium methoxide yielded the corresponding free S-nucleosides 5 and 6, respectively. Furthermore, the reaction of potassium salt of 2-thioxo-5,6,7,8-tetrahydrobenzo thieno[2,3-d]pyrimidin-4(3H)-one 8 with 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide 9, afforded 10. Deacetylation of the latter by using methanolic sodium methoxide yielded the corresponding S-glycoside, 2-(2 ,3 ,4 ,6 -tetra-hydroxy-β-D-glucopyranosylthio)-5,6,7,8-tetrahydro-benzothieno [2,3-d]pyrimidin-4-one 11. The structural elucidation of the new nucleosides formed was reported.

The glycosylation of azomethines such as (III) and (X) provides access to novel thiopyrimidine N‐nucleosides (VI), (VII), (XIII) and (XIV) which demonstrate moderate antibacterial and antifungal activities.

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Fluorinated nucleosides very important in increased biological and chemical stability of organ fluorine compounds. Synthesis of two 5-(Trifluoromethyl)-1H-benzimidazole derivatives (3) and (4).Ribosylation of each compound (3) and (4) with 1-O-acetyl-2,3,5-tri-O-benzoyl-β-D-ribofuranose (6) afforded mixture b-and a-anomeric of the benzoylated nucleoside derivatives (8), (9) and b-anomeric (12), respectively. Debenzoylation of the protected nucleosides by reaction with sodium metal in dry methanol yielded the corresponding free N-nucleosides (10), (11) and (13) respectively. The new synthesized compounds were characterized using the well-known spectroscopic tools (IR, 1 HNMR, 13 CNMR and mass spectroscopy).

Condensation of 7-ethyl-8-hydrazinotheophylline 1 with aldohexoses 2-4 and aldopentoses 5,6 by heating in an aqueous ethanolic solution and in the presence of a catalytic amount of acetic acid gives the corresponding hitherto unknown aldehydo-sugar (7-ethyl-8-theophyllinyl)hydrazones 7-11. The structures of the sugar hydrazones 7-11 were confirmed by their elemental analyses and spectral (IR, 1 H NMR and FAB-MS) data. Acetylation of the sugar hydrazones 7-11 with acetic anhydride in pyridine at room temperature gave the corresponding poly-O-acetyl derivatives 12-16. Attempted dehydrogenative cyclization of the products 7-11 and 12-16 using various conditions did not afford the corresponding acyclo C-nucleosides (R= sugar or R`= acetylated sugar) 18. On the other hand, the reaction of 7-11 or 12-16 with bromine in acetic acid and sodium acetate afforded 8-bromo-7-ethyltheophylline 17. The structural elucidation of products is reported and also some of the products were screened for their antimicrobial activity.

1,2,4]Triazolo[5,1-b]-and [1,2,4]triazino [3,2-b] quinazolines have been ribosylated by coupling with 1-O-acetyl-2,3,5-tri-Obenzoyl--D-ribofuranose and by using the silylation method, followed by debenzoylation by methanolic sodium methoxide to afford the corresponding free N-nucleosides. Nucleosides obtained have been identified by their spectral analysis. From the UVvisible and fluorescence studies of some nucleosides synthesized, it is found that they have fluorescence properties. 6 ) 7.20 (d, 2H, aromatic protons, = 8.0 Hz), 7.70 (d, 2H, aromatic protons, = 8.0 Hz), 7.90 (m, 5H, aromatic protons), 11.50 (s, 1H, NH); MS (m/z) = 262 (M + , 70%). Anal. Calcd for C 15 H

The condensation of 6-amino-2-thioxo-2,3-dihydro-1H-pyrimidine-4-one [compound (1)] with aromatic aldehydes (2) afforded azomethine derivatives (3). The formed azomethines underwent glycosidation with α-acetobromoglucose (4) to form the corresponding pyrimidine N-glycosides (6) and not S-glycosides (5). The interaction of (3) with 1-O-acetyl-2, 3, 5-tri-O-benzoyl-β-D-ribofuranose (8) afforded the corresponding pyrimidine N-riboside (10) and not S-riboside (9). Deacetylation and debenzoylation of each of (6) and (10) by using methanolic sodium methoxide afforded the corresponding free N-nucleosides (7) and (11), respectively. Next, the reaction of 2-benzylthio-6-benzylidenaminouracil (13) with (4) and (8) did not yield the corresponding protected N-nucleosides (14) and (17), whereas it afforded (15) and (18), respectively. The latter compounds (15) and (18) were stirred in methanolic sodium methoxide to yield the corresponding free N-nucleosides (16) and (19), respectively. The structures of products have been elucidated and reported and also some of the products were screened for their antimicrobial activity. Graphical Abstract:

Synthesis of 8-trifluloromethyl quinazolin-2,4-(1H,3H)-dione 2. which have been ribosylated by coupling with 1-O-acetyl-2,3,5-tri-O-benzoyl--D-ribofuranose 4 by using the silylation method, afforded mixture -and -anomeric of the benzoylated nucleoside derivatives 5 and 6, respectively. Debenzoylation of each of 5 and 6 by sodium metal in dry methanol to afford the corresponding free nucleosides 7 and 8 respectively. The structures of the newly synthesis compounds have been confirmed on the basis of elemental analyses, IR, 1 HNMR, 13 CNMR and Mass spectral data.