Nucleosides 5¹⁵: Synthesis of Novel 1,2,4-Triazolo[3,4-c]-1,2,4-Triazole Nucleosides

Abstract

Ribosylation of 3-methylthio-5-phenyl-1,2,4-triazole (1) with ribose derivative 2 gave the protected 1,2,4-triazole-nucleoside 3, which reacted with hydrazine hydrate to afford the 3-hydrazino-1,2,4-triazole derivative 5. Reaction of 5 with aromatic aldehydes yielded the corresponding hydrazones 6, which cyclized under bromination in acetic acid to give 8. Debenzoylation of 8 afforded novel 1,2,4-triazolo[3,4-c]-1,2,4-triazole nucleosides 9.

Nucleosides 8 [18]: Ribosylation of Fused Quinazolines—Synthesis of New [1,2,4]Triazolo[5,1‐b]‐ and [1,2,4]Triazino[3,2‐b]quinazoline Nucleosides of Fluorescence Interest

“…Their IR spectra revealed three characteristic bands for (C=O)-stretching bands of product 16 and four bands for product 20 (see Section 2). The 1 H NMR spectra in CDCl 3 of 16 and 20 showed as in the case of that of compounds 7-10 signals at 6.10-6.15 assigned to the anomeric proton of the ribose moiety with a spin-spin coupling constant equal to 7.5 Hz ( -configuration [18][19][20][21][22][23][24]). 13 C NMR Spectrum in CDCl 3 of 16 as an example revealed signals at 29,50,59,71,78,84,93,121,[125][126][127][128][129][130][131][132][133][134][135][136][137][138][139][140]151,159,164,168 (CO).…”

“…The structures of the latter products 7-10, 16, and 20 were established and confirmed on the bases of their elemental analyses and spectral data. Thus, their 1 H NMR spectra in CDCl 3 showed a doublet signal at 6.10-6.15 assigned to the anomeric proton of the ribose moiety with a spin-spin coupling constant equal to 7.5 Hz, which corresponds to a diaxial orientation for the 1 -and 2 -H protons; that is, the -configuration (high 1 ,2 ) [18][19][20][21][22][23][24]. 13 The structure of nucleoside 10 may exist in two forms, thiol form (10A) and thione form (10B or 10C) (Scheme 2).…”

“…In the view of our observations of the aforementioned biological and fluorescence [1-4, 15, 17] importance of quinazoline derivatives and as part of our continuing interest in the synthesis of new nucleosides [18][19][20][21][22][23][24] as expected as new fluorescent molecules, it has encouraged us to study a synthetic strategy of new derivatives of [1,2,4]triazolo [5,1-b]-and [1,2,4]triazino [3,2-b]quinazoline nucleosides of fluorescence 2 Journal of Chemistry interest, which have not been yet reported in the literature. Our final goal will be directed to find new nucleosides as expected to be fluorescent and to study their biological activity in further investigations.…”