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

Abstract

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

Synthesis New of Nucleoside of 1,3-bis-(2,3,5-tri-O-Benzoyl-β-D-Ribofuranosyl)-8-(Trifluoromethyl)-2-Methyl-4-Quinazolinone

“…For the observation of CF3 groups, coupling constants for protons of the ribose moiety of an atom on N1 suggests this could be a cancellation of through-space and through-bond couplings. Meanwhile the protons' ribose moiety on N3 decoupling was not affected by 19 F. The proton's two glycoside bonds on N1 and N3 produced doublet signals at δ6.69 (d, 1H, 3 JH-H = 5.1 Hz) H1'' and 5.69-5.63 (d,1H; 3 JH-H = 4.25 Hz) H1' for compound 6, which confirmed the β-anomeric configuration [4][5][6][7].…”

Synthesis of 8-Trifluloromethyl-2-Thioquinazolin-(3H)-4-One Nucleosides

“…1 H NMR spectra of compound 5 and 6 showed in each case a doublet signals at δ 5.98 (d, 1H, J = 7.5 Hz) H 1`f or compound 5 and at δ 5.17 (d, 1H, J = 7.5 Hz) H 1`f or free nucleoside compound 6 assigned to the anomeric proton of the ribose moiety with spin-spin coupling constant (J 1',2' ) equal to 7.5 Hz, which confirms the β-anomeric configuration. (Break,2017;Break et al, 2014;Break et al, 2013;Break & Mosselhi, 2012;Mosselhi & Break, 2011;Break et al, 2010;Chien T.-C. et al, 2005 andAbdullah Hijazi, 1988). The 1 H NMR of compounds 5 and 6 showed the expected base moiety protons in addition to the sugar moiety protons (see the Experimental section).…”